A PET system based on 2-18FDG production with a low energy electrostatic proton accelerator and a dual headed PET scanner.

PubMed

Sandell, A; Ohlsson, T; Erlandsson, K; Hellborg, R; Strand, S E

1992-01-01

We have developed a comparatively inexpensive PET system, based on a rotating scanner with two scintillation camera heads, and a nearby low energy electrostatic proton accelerator for production of short-lived radionuclides. Using a 6 MeV proton beam of 5 microA, and by optimization of the target geometry for the 18O(p,n)18F reaction, 750 MBq of 2-18FDG can be obtained. The PET scanner shows a spatial resolution of 6 mm (FWHM) and a sensitivity of 80 s-1kBq-1ml-1 (3 kcps/microCi/ml). Various corrections are included in the imaging process, to compensate for spatial and temporal response variations in the detector system. Both filtered backprojection and iterative reconstruction methods are employed. Clinical studies have been performed with acquisition times of 30-40 min. The system will be used for clinical experimental research with short- as well as long-lived positron emitters. Also the possibility of true 3D reconstruction is under evaluation.

Joint project of the international network of agencies for health technology assessment--Part 1: Survey results on diffusion, assessment, and clinical use of positron emission tomography.

PubMed

Hastings, John; Adams, Elizabeth J

2006-01-01

The International Network of Agencies for Health Technology Assessment (INAHTA) has been tracking activities associated with the clinical use of positron emission tomography (PET) in its members' healthcare systems since 1997 and published its first Joint Project report on PET in 1999. Part 1 of this Joint Project report presents survey results on diffusion, assessment activities, and policy for clinical use related to PET among INAHTA members since 1999. INAHTA members were surveyed in 2003-2004. Twenty-seven INAHTA agencies (69 percent response rate) from nineteen countries responded to the survey. Dedicated PET systems are the most universally installed systems to date. Mobile scanners and modified gamma cameras are used occasionally as lower cost alternatives, and interest in PET-computed tomography hybrid models is rising despite limited assessment of impact on service planning. PET was used and assessed most commonly for managing patients with cancer. All respondents reported having some form of public funding for clinical PET frequently linked to data collection for the purpose of gathering evidence to refine clinical use and guide resource allocation toward indications that maximize clinical and cost-effectiveness. The use of HTA within a continuous quality improvement framework can help optimize scarce resources for evaluation and use of high cost diagnostic technologies such as PET, particularly where potential clinical or cost-effectiveness is considerable but conclusive evidence is lacking.

MO-AB-206-02: Testing Gamma Cameras Based On TG177 WG Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Halama, J.

2016-06-15

This education session will cover the physics and operation principles of gamma cameras and PET scanners. The first talk will focus on PET imaging. An overview of the principles of PET imaging will be provided, including positron decay physics, and the transition from 2D to 3D imaging. More recent advances in hardware and software will be discussed, such as time-of-flight imaging, and improvements in reconstruction algorithms that provide for options such as depth-of-interaction corrections. Quantitative applications of PET will be discussed, as well as the requirements for doing accurate quantitation. Relevant performance tests will also be described. Learning Objectives: Bemore » able to describe basic physics principles of PET and operation of PET scanners. Learn about recent advances in PET scanner hardware technology. Be able to describe advances in reconstruction techniques and improvements Be able to list relevant performance tests. The second talk will focus on gamma cameras. The Nuclear Medicine subcommittee has charged a task group (TG177) to develop a report on the current state of physics testing of gamma cameras, SPECT, and SPECT/CT systems. The report makes recommendations for performance tests to be done for routine quality assurance, annual physics testing, and acceptance tests, and identifies those needed satisfy the ACR accreditation program and The Joint Commission imaging standards. The report is also intended to be used as a manual with detailed instructions on how to perform tests under widely varying conditions. Learning Objectives: At the end of the presentation members of the audience will: Be familiar with the tests recommended for routine quality assurance, annual physics testing, and acceptance tests of gamma cameras for planar imaging. Be familiar with the tests recommended for routine quality assurance, annual physics testing, and acceptance tests of SPECT systems. Be familiar with the tests of a SPECT/CT system that include the CT images for SPECT reconstructions. Become knowledgeable of items to be included in annual acceptance testing reports including CT dosimetry and PACS monitor measurements. T. Turkington, GE Healthcare.« less

Using triple gamma coincidences with a pixelated semiconductor Compton-PET scanner: a simulation study

NASA Astrophysics Data System (ADS)

Kolstein, M.; Chmeissani, M.

2016-01-01

The Voxel Imaging PET (VIP) Pathfinder project presents a novel design using pixelated semiconductor detectors for nuclear medicine applications to achieve the intrinsic image quality limits set by physics. The conceptual design can be extended to a Compton gamma camera. The use of a pixelated CdTe detector with voxel sizes of 1 × 1 × 2 mm3 guarantees optimal energy and spatial resolution. However, the limited time resolution of semiconductor detectors makes it impossible to use Time Of Flight (TOF) with VIP PET. TOF is used in order to improve the signal to noise ratio (SNR) by using only the most probable portion of the Line-Of-Response (LOR) instead of its entire length. To overcome the limitation of CdTe time resolution, we present in this article a simulation study using β+-γ emitting isotopes with a Compton-PET scanner. When the β+ annihilates with an electron it produces two gammas which produce a LOR in the PET scanner, while the additional gamma, when scattered in the scatter detector, provides a Compton cone that intersects with the aforementioned LOR. The intersection indicates, within a few mm of uncertainty along the LOR, the origin of the beta-gamma decay. Hence, one can limit the part of the LOR used by the image reconstruction algorithm.

SU-D-9A-01: Listmode-Driven Optimal Gating (OG) Respiratory Motion Management: Potential Impact On Quantitative PET Imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, K; Hristov, D

2014-06-01

Purpose: To evaluate the potential impact of listmode-driven amplitude based optimal gating (OG) respiratory motion management technique on quantitative PET imaging. Methods: During the PET acquisitions, an optical camera tracked and recorded the motion of a tool placed on top of patients' torso. PET event data were utilized to detect and derive a motion signal that is directly coupled with a specific internal organ. A radioactivity-trace was generated from listmode data by accumulating all prompt counts in temporal bins matching the sampling rate of the external tracking device. Decay correction for 18F was performed. The image reconstructions using OG respiratorymore » motion management technique that uses 35% of total radioactivity counts within limited motion amplitudes were performed with external motion and radioactivity traces separately with ordered subset expectation maximization (OSEM) with 2 iterations and 21 subsets. Standard uptake values (SUVs) in a tumor region were calculated to measure the effect of using radioactivity trace for motion compensation. Motion-blurred 3D static PET image was also reconstructed with all counts and the SUVs derived from OG images were compared with SUVs from 3D images. Results: A 5.7 % increase of the maximum SUV in the lesion was found for optimal gating image reconstruction with radioactivity trace when compared to a static 3D image. The mean and maximum SUVs on the image that was reconstructed with radioactivity trace were found comparable (0.4 % and 4.5 % increase, respectively) to the values derived from the image that was reconstructed with external trace. Conclusion: The image reconstructed using radioactivity trace showed that the blurring due to the motion was reduced with impact on derived SUVs. The resolution and contrast of the images reconstructed with radioactivity trace were comparable to the resolution and contrast of the images reconstructed with external respiratory traces. Research supported by Siemens.« less

Performance evaluation and optimization of the MiniPET-II scanner

NASA Astrophysics Data System (ADS)

Lajtos, Imre; Emri, Miklos; Kis, Sandor A.; Opposits, Gabor; Potari, Norbert; Kiraly, Beata; Nagy, Ferenc; Tron, Lajos; Balkay, Laszlo

2013-04-01

This paper presents results of the performance of a small animal PET system (MiniPET-II) installed at our Institute. MiniPET-II is a full ring camera that includes 12 detector modules in a single ring comprised of 1.27×1.27×12 mm3 LYSO scintillator crystals. The axial field of view and the inner ring diameter are 48 mm and 211 mm, respectively. The goal of this study was to determine the NEMA-NU4 performance parameters of the scanner. In addition, we also investigated how the calculated parameters depend on the coincidence time window (τ=2, 3 and 4 ns) and the low threshold settings of the energy window (Elt=250, 350 and 450 keV). Independent measurements supported optimization of the effective system radius and the coincidence time window of the system. We found that the optimal coincidence time window and low threshold energy window are 3 ns and 350 keV, respectively. The spatial resolution was close to 1.2 mm in the center of the FOV with an increase of 17% at the radial edge. The maximum value of the absolute sensitivity was 1.37% for a point source. Count rate tests resulted in peak values for the noise equivalent count rate (NEC) curve and scatter fraction of 14.2 kcps (at 36 MBq) and 27.7%, respectively, using the rat phantom. Numerical values of the same parameters obtained for the mouse phantom were 55.1 kcps (at 38.8 MBq) and 12.3%, respectively. The recovery coefficients of the image quality phantom ranged from 0.1 to 0.87. Altering the τ and Elt resulted in substantial changes in the NEC peak and the sensitivity while the effect on the image quality was negligible. The spatial resolution proved to be, as expected, independent of the τ and Elt. The calculated optimal effective system radius (resulting in the best image quality) was 109 mm. Although the NEC peak parameters do not compare favorably with those of other small animal scanners, it can be concluded that under normal counting situations the MiniPET-II imaging capability assures remarkably good image quality, sensitivity and spatial resolution.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Turkington, T.

This education session will cover the physics and operation principles of gamma cameras and PET scanners. The first talk will focus on PET imaging. An overview of the principles of PET imaging will be provided, including positron decay physics, and the transition from 2D to 3D imaging. More recent advances in hardware and software will be discussed, such as time-of-flight imaging, and improvements in reconstruction algorithms that provide for options such as depth-of-interaction corrections. Quantitative applications of PET will be discussed, as well as the requirements for doing accurate quantitation. Relevant performance tests will also be described. Learning Objectives: Bemore » able to describe basic physics principles of PET and operation of PET scanners. Learn about recent advances in PET scanner hardware technology. Be able to describe advances in reconstruction techniques and improvements Be able to list relevant performance tests. The second talk will focus on gamma cameras. The Nuclear Medicine subcommittee has charged a task group (TG177) to develop a report on the current state of physics testing of gamma cameras, SPECT, and SPECT/CT systems. The report makes recommendations for performance tests to be done for routine quality assurance, annual physics testing, and acceptance tests, and identifies those needed satisfy the ACR accreditation program and The Joint Commission imaging standards. The report is also intended to be used as a manual with detailed instructions on how to perform tests under widely varying conditions. Learning Objectives: At the end of the presentation members of the audience will: Be familiar with the tests recommended for routine quality assurance, annual physics testing, and acceptance tests of gamma cameras for planar imaging. Be familiar with the tests recommended for routine quality assurance, annual physics testing, and acceptance tests of SPECT systems. Be familiar with the tests of a SPECT/CT system that include the CT images for SPECT reconstructions. Become knowledgeable of items to be included in annual acceptance testing reports including CT dosimetry and PACS monitor measurements. T. Turkington, GE Healthcare.« less

Thermal regulation of tightly packed solid-state photodetectors in a 1 mm3 resolution clinical PET system

PubMed Central

Vandenbroucke, A.; Innes, D.; Lau, F. W. Y.; Hsu, D. F. C.; Reynolds, P. D.; Levin, Craig S.

2015-01-01

Purpose: Silicon photodetectors are of significant interest for use in positron emission tomography (PET) systems due to their compact size, insensitivity to magnetic fields, and high quantum efficiency. However, one of their main disadvantages is fluctuations in temperature cause strong shifts in gain of the devices. PET system designs with high photodetector density suffer both increased thermal density and constrained options for thermally regulating the devices. This paper proposes a method of thermally regulating densely packed silicon photodetectors in the context of a 1 mm3 resolution, high-sensitivity PET camera dedicated to breast imaging. Methods: The PET camera under construction consists of 2304 units, each containing two 8 × 8 arrays of 1 mm3 LYSO crystals coupled to two position sensitive avalanche photodiodes (PSAPD). A subsection of the proposed camera with 512 PSAPDs has been constructed. The proposed thermal regulation design uses water-cooled heat sinks, thermoelectric elements, and thermistors to measure and regulate the temperature of the PSAPDs in a novel manner. Active cooling elements, placed at the edge of the detector stack due to limited access, are controlled based on collective leakage current and temperature measurements in order to keep all the PSAPDs at a consistent temperature. This thermal regulation design is characterized for the temperature profile across the camera and for the time required for cooling changes to propagate across the camera. These properties guide the implementation of a software-based, cascaded proportional-integral-derivative control loop that controls the current through the Peltier elements by monitoring thermistor temperature and leakage current. The stability of leakage current, temperature within the system using this control loop is tested over a period of 14 h. The energy resolution is then measured over a period of 8.66 h. Finally, the consistency of PSAPD gain between independent operations of the camera over 10 days is tested. Results: The PET camera maintains a temperature of 18.00 ± 0.05 °C over the course of 12 h while the ambient temperature varied 0.61 °C, from 22.83 to 23.44 °C. The 511 keV photopeak energy resolution over a period of 8.66 h is measured to be 11.3% FWHM with a maximum photopeak fluctuation of 4 keV. Between measurements of PSAPD gain separated by at least 2 day, the maximum photopeak shift was 6 keV. Conclusions: The proposed thermal regulation scheme for tightly packed silicon photodetectors provides for stable operation of the constructed subsection of a PET camera over long durations of time. The energy resolution of the system is not degraded despite shifts in ambient temperature and photodetector heat generation. The thermal regulation scheme also provides a consistent operating environment between separate runs of the camera over different days. Inter-run consistency allows for reuse of system calibration parameters from study to study, reducing the time required to calibrate the system and hence to obtain a reconstructed image. PMID:25563270

Thermal regulation of tightly packed solid-state photodetectors in a 1 mm{sup 3} resolution clinical PET system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Freese, D. L.; Vandenbroucke, A.; Innes, D.

2015-01-15

Purpose: Silicon photodetectors are of significant interest for use in positron emission tomography (PET) systems due to their compact size, insensitivity to magnetic fields, and high quantum efficiency. However, one of their main disadvantages is fluctuations in temperature cause strong shifts in gain of the devices. PET system designs with high photodetector density suffer both increased thermal density and constrained options for thermally regulating the devices. This paper proposes a method of thermally regulating densely packed silicon photodetectors in the context of a 1 mm{sup 3} resolution, high-sensitivity PET camera dedicated to breast imaging. Methods: The PET camera under constructionmore » consists of 2304 units, each containing two 8 × 8 arrays of 1 mm{sup 3} LYSO crystals coupled to two position sensitive avalanche photodiodes (PSAPD). A subsection of the proposed camera with 512 PSAPDs has been constructed. The proposed thermal regulation design uses water-cooled heat sinks, thermoelectric elements, and thermistors to measure and regulate the temperature of the PSAPDs in a novel manner. Active cooling elements, placed at the edge of the detector stack due to limited access, are controlled based on collective leakage current and temperature measurements in order to keep all the PSAPDs at a consistent temperature. This thermal regulation design is characterized for the temperature profile across the camera and for the time required for cooling changes to propagate across the camera. These properties guide the implementation of a software-based, cascaded proportional-integral-derivative control loop that controls the current through the Peltier elements by monitoring thermistor temperature and leakage current. The stability of leakage current, temperature within the system using this control loop is tested over a period of 14 h. The energy resolution is then measured over a period of 8.66 h. Finally, the consistency of PSAPD gain between independent operations of the camera over 10 days is tested. Results: The PET camera maintains a temperature of 18.00 ± 0.05 °C over the course of 12 h while the ambient temperature varied 0.61 °C, from 22.83 to 23.44 °C. The 511 keV photopeak energy resolution over a period of 8.66 h is measured to be 11.3% FWHM with a maximum photopeak fluctuation of 4 keV. Between measurements of PSAPD gain separated by at least 2 day, the maximum photopeak shift was 6 keV. Conclusions: The proposed thermal regulation scheme for tightly packed silicon photodetectors provides for stable operation of the constructed subsection of a PET camera over long durations of time. The energy resolution of the system is not degraded despite shifts in ambient temperature and photodetector heat generation. The thermal regulation scheme also provides a consistent operating environment between separate runs of the camera over different days. Inter-run consistency allows for reuse of system calibration parameters from study to study, reducing the time required to calibrate the system and hence to obtain a reconstructed image.« less

Molecular imaging of angiogenesis with SPECT

PubMed Central

Boerman, Otto C.

2010-01-01

Single-photon emission computed tomography (SPECT) and position emission tomography (PET) are the two main imaging modalities in nuclear medicine. SPECT imaging is more widely available than PET imaging and the radionuclides used for SPECT are easier to prepare and usually have a longer half-life than those used for PET. In addition, SPECT is a less expensive technique than PET. Commonly used gamma emitters are: 99mTc (Emax 141 keV, T1/2 6.02 h), 123I (Emax 529 keV, T1/2 13.0 h) and 111In (Emax 245 keV, T1/2 67.2 h). Compared to clinical SPECT, PET has a higher spatial resolution and the possibility to more accurately estimate the in vivo concentration of a tracer. In preclinical imaging, the situation is quite different. The resolution of microSPECT cameras (<0.5 mm) is higher than that of microPET cameras (>1.5 mm). In this report, studies on new radiolabelled tracers for SPECT imaging of angiogenesis in tumours are reviewed. PMID:20617435

MO-AB-206-00: Nuclear Medicine Physics and Testing

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

This education session will cover the physics and operation principles of gamma cameras and PET scanners. The first talk will focus on PET imaging. An overview of the principles of PET imaging will be provided, including positron decay physics, and the transition from 2D to 3D imaging. More recent advances in hardware and software will be discussed, such as time-of-flight imaging, and improvements in reconstruction algorithms that provide for options such as depth-of-interaction corrections. Quantitative applications of PET will be discussed, as well as the requirements for doing accurate quantitation. Relevant performance tests will also be described. Learning Objectives: Bemore » able to describe basic physics principles of PET and operation of PET scanners. Learn about recent advances in PET scanner hardware technology. Be able to describe advances in reconstruction techniques and improvements Be able to list relevant performance tests. The second talk will focus on gamma cameras. The Nuclear Medicine subcommittee has charged a task group (TG177) to develop a report on the current state of physics testing of gamma cameras, SPECT, and SPECT/CT systems. The report makes recommendations for performance tests to be done for routine quality assurance, annual physics testing, and acceptance tests, and identifies those needed satisfy the ACR accreditation program and The Joint Commission imaging standards. The report is also intended to be used as a manual with detailed instructions on how to perform tests under widely varying conditions. Learning Objectives: At the end of the presentation members of the audience will: Be familiar with the tests recommended for routine quality assurance, annual physics testing, and acceptance tests of gamma cameras for planar imaging. Be familiar with the tests recommended for routine quality assurance, annual physics testing, and acceptance tests of SPECT systems. Be familiar with the tests of a SPECT/CT system that include the CT images for SPECT reconstructions. Become knowledgeable of items to be included in annual acceptance testing reports including CT dosimetry and PACS monitor measurements. T. Turkington, GE Healthcare.« less

Development of a PET/Cerenkov-light hybrid imaging system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yamamoto, Seiichi, E-mail: s-yama@met.nagoya-u.ac.jp; Hamamura, Fuka; Kato, Katsuhiko

2014-09-15

Purpose: Cerenkov-light imaging is a new molecular imaging technology that detects visible photons from high-speed electrons using a high sensitivity optical camera. However, the merit of Cerenkov-light imaging remains unclear. If a PET/Cerenkov-light hybrid imaging system were developed, the merit of Cerenkov-light imaging would be clarified by directly comparing these two imaging modalities. Methods: The authors developed and tested a PET/Cerenkov-light hybrid imaging system that consists of a dual-head PET system, a reflection mirror located above the subject, and a high sensitivity charge coupled device (CCD) camera. The authors installed these systems inside a black box for imaging the Cerenkov-light.more » The dual-head PET system employed a 1.2 × 1.2 × 10 mm{sup 3} GSO arranged in a 33 × 33 matrix that was optically coupled to a position sensitive photomultiplier tube to form a GSO block detector. The authors arranged two GSO block detectors 10 cm apart and positioned the subject between them. The Cerenkov-light above the subject is reflected by the mirror and changes its direction to the side of the PET system and is imaged by the high sensitivity CCD camera. Results: The dual-head PET system had a spatial resolution of ∼1.2 mm FWHM and sensitivity of ∼0.31% at the center of the FOV. The Cerenkov-light imaging system's spatial resolution was ∼275μm for a {sup 22}Na point source. Using the combined PET/Cerenkov-light hybrid imaging system, the authors successfully obtained fused images from simultaneously acquired images. The image distributions are sometimes different due to the light transmission and absorption in the body of the subject in the Cerenkov-light images. In simultaneous imaging of rat, the authors found that {sup 18}F-FDG accumulation was observed mainly in the Harderian gland on the PET image, while the distribution of Cerenkov-light was observed in the eyes. Conclusions: The authors conclude that their developed PET/Cerenkov-light hybrid imaging system is useful to evaluate the merits and the limitations of Cerenkov-light imaging in molecular imaging research.« less

New cardiac cameras: single-photon emission CT and PET.

PubMed

Slomka, Piotr J; Berman, Daniel S; Germano, Guido

2014-07-01

Nuclear cardiology instrumentation has evolved significantly in the recent years. Concerns about radiation dose and long acquisition times have propelled developments of dedicated high-efficiency cardiac SPECT scanners. Novel collimator designs, such as multipinhole or locally focusing collimators arranged in geometries that are optimized for cardiac imaging, have been implemented to enhance photon-detection sensitivity. Some of these new SPECT scanners use solid-state photon detectors instead of photomultipliers to improve image quality and to reduce the scanner footprint. These new SPECT devices allow dramatic up to 7-fold reduction in acquisition times or similar reduction in radiation dose. In addition, new hardware for photon attenuation correction allowing ultralow radiation doses has been offered by some vendors. To mitigate photon attenuation artifacts for the new SPECT scanners not equipped with attenuation correction hardware, 2-position (upright-supine or prone-supine) imaging has been proposed. PET hardware developments have been primarily driven by the requirements of oncologic imaging, but cardiac imaging can benefit from improved PET image quality and improved sensitivity of 3D systems. The time-of-flight reconstruction combined with resolution recovery techniques is now implemented by all major PET vendors. These new methods improve image contrast and image resolution and reduce image noise. High-sensitivity 3D PET without interplane septa allows reduced radiation dose for cardiac perfusion imaging. Simultaneous PET/MR hybrid system has been developed. Solid-state PET detectors with avalanche photodiodes or digital silicon photomultipliers have been introduced, and they offer improved imaging characteristics and reduced sensitivity to electromagnetic MR fields. Higher maximum count rate of the new PET detectors allows routine first-pass Rb-82 imaging, with 3D PET acquisition enabling clinical utilization of dynamic imaging with myocardial flow measurements for this tracer. The availability of high-end CT component in most PET/CT configurations enables hybrid multimodality cardiac imaging protocols with calcium scoring or CT angiography or both. Copyright © 2014. Published by Elsevier Inc.

Imaging grafted cells with [18F]FHBG using an optimized HSV1-TK mammalian expression vector in a brain injury rodent model.

PubMed

Salabert, Anne-Sophie; Vaysse, Laurence; Beaurain, Marie; Alonso, Mathieu; Arribarat, Germain; Lotterie, Jean-Albert; Loubinoux, Isabelle; Tafani, Mathieu; Payoux, Pierre

2017-01-01

Cell transplantation is an innovative therapeutic approach after brain injury to compensate for tissue damage. To have real-time longitudinal monitoring of intracerebrally grafted cells, we explored the feasibility of a molecular imaging approach using thymidine kinase HSV1-TK gene encoding and [18F]FHBG as a reporter probe to image enzyme expression. A stable neuronal cell line expressing HSV1-TK was developed with an optimised mammalian expression vector to ensure long-term transgene expression. After [18F]FHBG incubation under defined parameters, calibration ranges from 1 X 104 to 3 X 106 Neuro2A-TK cells were analysed by gamma counter or by PET-camera. In parallel, grafting with different quantities of [18F]FHBG prelabelled Neuro2A-TK cells was carried out in a rat brain injury model induced by stereotaxic injection of malonate toxin. Image acquisition of the rats was then performed with PET/CT camera to study the [18F]FHBG signal of transplanted cells in vivo. Under the optimised incubation conditions, [18F]FHBG cell uptake rate was around 2.52%. In-vitro calibration range analysis shows a clear linear correlation between the number of cells and the signal intensity. The PET signal emitted into rat brain correlated well with the number of cells injected and the number of surviving grafted cells was recorded via the in-vitro calibration range. PET/CT acquisitions also allowed validation of the stereotaxic injection procedure. Technique sensitivity was evaluated under 5 X 104 grafted cells in vivo. No [18F]FHBG or [18F]metabolite release was observed showing a stable cell uptake even 2 h post-graft. The development of this kind of approach will allow grafting to be controlled and ensure longitudinal follow-up of cell viability and biodistribution after intracerebral injection.

Engineering and performance (NEMA and animal) of a lower-cost higher-resolution animal PET/CT scanner using photomultiplier-quadrant-sharing detectors.

PubMed

Wong, Wai-Hoi; Li, Hongdi; Baghaei, Hossain; Zhang, Yuxuan; Ramirez, Rocio A; Liu, Shitao; Wang, Chao; An, Shaohui

2012-11-01

The dedicated murine PET (MuPET) scanner is a high-resolution, high-sensitivity, and low-cost preclinical PET camera designed and manufactured at our laboratory. In this article, we report its performance according to the NU 4-2008 standards of the National Electrical Manufacturers Association (NEMA). We also report the results of additional phantom and mouse studies. The MuPET scanner, which is integrated with a CT camera, is based on the photomultiplier-quadrant-sharing concept and comprises 180 blocks of 13 × 13 lutetium yttrium oxyorthosilicate crystals (1.24 × 1.4 × 9.5 mm(3)) and 210 low-cost 19-mm photomultipliers. The camera has 78 detector rings, with an 11.6-cm axial field of view and a ring diameter of 16.6 cm. We measured the energy resolution, scatter fraction, sensitivity, spatial resolution, and counting rate performance of the scanner. In addition, we scanned the NEMA image-quality phantom, Micro Deluxe and Ultra-Micro Hot Spot phantoms, and 2 healthy mice. The system average energy resolution was 14% at 511 keV. The average spatial resolution at the center of the field of view was about 1.2 mm, improving to 0.8 mm and remaining below 1.2 mm in the central 6-cm field of view when a resolution-recovery method was used. The absolute sensitivity of the camera was 6.38% for an energy window of 350-650 keV and a coincidence timing window of 3.4 ns. The system scatter fraction was 11.9% for the NEMA mouselike phantom and 28% for the ratlike phantom. The maximum noise-equivalent counting rate was 1,100 at 57 MBq for the mouselike phantom and 352 kcps at 65 MBq for the ratlike phantom. The 1-mm fillable rod was clearly observable using the NEMA image-quality phantom. The images of the Ultra-Micro Hot Spot phantom also showed the 1-mm hot rods. In the mouse studies, both the left and right ventricle walls were clearly observable, as were the Harderian glands. The MuPET camera has excellent resolution, sensitivity, counting rate, and imaging performance. The data show it is a powerful scanner for preclinical animal study and pharmaceutical development.

PET attenuation correction for flexible MRI surface coils in hybrid PET/MRI using a 3D depth camera

NASA Astrophysics Data System (ADS)

Frohwein, Lynn J.; Heß, Mirco; Schlicher, Dominik; Bolwin, Konstantin; Büther, Florian; Jiang, Xiaoyi; Schäfers, Klaus P.

2018-01-01

PET attenuation correction for flexible MRI radio frequency surface coils in hybrid PET/MRI is still a challenging task, as position and shape of these coils conform to large inter-patient variabilities. The purpose of this feasibility study is to develop a novel method for the incorporation of attenuation information about flexible surface coils in PET reconstruction using the Microsoft Kinect V2 depth camera. The depth information is used to determine a dense point cloud of the coil’s surface representing the shape of the coil. From a CT template—acquired once in advance—surface information of the coil is extracted likewise and converted into a point cloud. The two point clouds are then registered using a combination of an iterative-closest-point (ICP) method and a partially rigid registration step. Using the transformation derived through the point clouds, the CT template is warped and thereby adapted to the PET/MRI scan setup. The transformed CT template is converted into an attenuation map from Hounsfield units into linear attenuation coefficients. The resulting fitted attenuation map is then integrated into the MRI-based patient-specific DIXON-based attenuation map of the actual PET/MRI scan. A reconstruction of phantom PET data acquired with the coil present in the field-of-view (FoV), but without the corresponding coil attenuation map, shows large artifacts in regions close to the coil. The overall count loss is determined to be around 13% compared to a PET scan without the coil present in the FoV. A reconstruction using the new μ-map resulted in strongly reduced artifacts as well as increased overall PET intensities with a remaining relative difference of about 1% to a PET scan without the coil in the FoV.

The origins of SPECT and SPECT/CT.

PubMed

Hutton, Brian F

2014-05-01

Single photon emission computed tomography (SPECT) has a long history of development since its initial demonstration by Kuhl and Edwards in 1963. Although clinical utility has been dominated by the rotating gamma camera, there have been many technological innovations with the recent popularity of organ-specific dedicated SPECT systems. The combination of SPECT and CT evolved from early transmission techniques used for attenuation correction with the initial commercial systems predating the release of PET/CT. The development and acceptance of SPECT/CT has been relatively slow with continuing debate as to what cost/performance ratio is justified. Increasingly, fully diagnostic CT is combined with SPECT so as to facilitate optimal clinical utility.

Timing Calibration in PET Using a Time Alignment Probe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moses, William W.; Thompson, Christopher J.

2006-05-05

We evaluate the Scanwell Time Alignment Probe for performing the timing calibration for the LBNL Prostate-Specific PET Camera. We calibrate the time delay correction factors for each detector module in the camera using two methods--using the Time Alignment Probe (which measures the time difference between the probe and each detector module) and using the conventional method (which measures the timing difference between all module-module combinations in the camera). These correction factors, which are quantized in 2 ns steps, are compared on a module-by-module basis. The values are in excellent agreement--of the 80 correction factors, 62 agree exactly, 17 differ bymore » 1 step, and 1 differs by 2 steps. We also measure on-time and off-time counting rates when the two sets of calibration factors are loaded into the camera and find that they agree within statistical error. We conclude that the performance using the Time Alignment Probe and conventional methods are equivalent.« less

Feasibility of deep-inspiration breath-hold PET/CT with short-time acquisition: detectability for pulmonary lesions compared with respiratory-gated PET/CT.

PubMed

Yamashita, Shozo; Yokoyama, Kunihiko; Onoguchi, Masahisa; Yamamoto, Haruki; Hiko, Shigeaki; Horita, Akihiro; Nakajima, Kenichi

2014-01-01

Deep-inspiration breath-hold (DIBH) PET/CT with short-time acquisition and respiratory-gated (RG) PET/CT are performed for pulmonary lesions to reduce the respiratory motion artifacts, and to obtain more accurate standardized uptake value (SUV). DIBH PET/CT demonstrates significant advantages in terms of rapid examination, good quality of CT images and low radiation exposure. On the other hand, the image quality of DIBH PET is generally inferior to that of RG PET because of short-time acquisition resulting in poor signal-to-noise ratio. In this study, RG PET has been regarded as a gold standard, and its detectability between DIBH and RG PET studies was compared using each of the most optimal reconstruction parameters. In the phantom study, the most optimal reconstruction parameters for DIBH and RG PET were determined. In the clinical study, 19 cases were examined using each of the most optimal reconstruction parameters. In the phantom study, the most optimal reconstruction parameters for DIBH and RG PET were different. Reconstruction parameters of DIBH PET could be obtained by reducing the number of subsets for those of RG PET in the state of fixing the number of iterations. In the clinical study, high correlation in the maximum SUV was observed between DIBH and RG PET studies. The clinical result was consistent with that of the phantom study surrounded by air since most of the lesions were located in the low pulmonary radioactivity. DIBH PET/CT may be the most practical method which can be the first choice to reduce respiratory motion artifacts if the detectability of DIBH PET is equivalent with that of RG PET. Although DIBH PET may have limitations in suboptimal signal-to-noise ratio, most of the lesions surrounded by low background radioactivity could provide nearly equivalent image quality between DIBH and RG PET studies when each of the most optimal reconstruction parameters was used.

Investigation of optimization-based reconstruction with an image-total-variation constraint in PET

NASA Astrophysics Data System (ADS)

Zhang, Zheng; Ye, Jinghan; Chen, Buxin; Perkins, Amy E.; Rose, Sean; Sidky, Emil Y.; Kao, Chien-Min; Xia, Dan; Tung, Chi-Hua; Pan, Xiaochuan

2016-08-01

Interest remains in reconstruction-algorithm research and development for possible improvement of image quality in current PET imaging and for enabling innovative PET systems to enhance existing, and facilitate new, preclinical and clinical applications. Optimization-based image reconstruction has been demonstrated in recent years of potential utility for CT imaging applications. In this work, we investigate tailoring the optimization-based techniques to image reconstruction for PET systems with standard and non-standard scan configurations. Specifically, given an image-total-variation (TV) constraint, we investigated how the selection of different data divergences and associated parameters impacts the optimization-based reconstruction of PET images. The reconstruction robustness was explored also with respect to different data conditions and activity up-takes of practical relevance. A study was conducted particularly for image reconstruction from data collected by use of a PET configuration with sparsely populated detectors. Overall, the study demonstrates the robustness of the TV-constrained, optimization-based reconstruction for considerably different data conditions in PET imaging, as well as its potential to enable PET configurations with reduced numbers of detectors. Insights gained in the study may be exploited for developing algorithms for PET-image reconstruction and for enabling PET-configuration design of practical usefulness in preclinical and clinical applications.

Myocardial perfusion imaging: Lessons learned and work to be done-update.

PubMed

Iskandrian, Ami E; Dilsizian, Vasken; Garcia, Ernest V; Beanlands, Rob S; Cerqueira, Manuel; Soman, Prem; Berman, Daniel S; Cuocolo, Alberto; Einstein, Andrew J; Morgan, Charity J; Hage, Fadi G; Schelbert, Heinrich R; Bax, Jeroen J; Wu, Joseph C; Shaw, Leslee J; Sadeghi, Mehran M; Tamaki, Nagara; Kaufmann, Philipp A; Gropler, Robert; Dorbala, Sharmila; Van Decker, William

2018-02-01

As the second term of our commitment to Journal begins, we, the editors, would like to reflect on a few topics that have relevance today. These include prognostication and paradigm shifts; Serial testing: How to handle data? Is the change in perfusion predictive of outcome and which one? Ischemia-guided therapy: fractional flow reserve vs perfusion vs myocardial blood flow; positron emission tomography (PET) imaging using Rubidium-82 vs N-13 ammonia vs F-18 Flurpiridaz; How to differentiate microvascular disease from 3-vessel disease by PET? The imaging scene outside the United States, what are the differences and similarities? Radiation exposure; Special issues with the new cameras? Is attenuation correction needed? Are there normal databases and are these specific to each camera system? And finally, hybrid imaging with single-photon emission tomography or PET combined with computed tomography angiography or coronary calcium score. We hope these topics are of interest to our readers.

High-performance electronics for time-of-flight PET systems

NASA Astrophysics Data System (ADS)

Choong, W.-S.; Peng, Q.; Vu, C. Q.; Turko, B. T.; Moses, W. W.

2013-01-01

We have designed and built a high-performance readout electronics system for time-of-flight positron emission tomography (TOF PET) cameras. The electronics architecture is based on the electronics for a commercial whole-body PET camera (Siemens/CPS Cardinal electronics), modified to improve the timing performance. The fundamental contributions in the electronics that can limit the timing resolution include the constant fraction discriminator (CFD), which converts the analog electrical signal from the photo-detector to a digital signal whose leading edge is time-correlated with the input signal, and the time-to-digital converter (TDC), which provides a time stamp for the CFD output. Coincident events are identified by digitally comparing the values of the time stamps. In the Cardinal electronics, the front-end processing electronics are performed by an Analog subsection board, which has two application-specific integrated circuits (ASICs), each servicing a PET block detector module. The ASIC has a built-in CFD and TDC. We found that a significant degradation in the timing resolution comes from the ASIC's CFD and TDC. Therefore, we have designed and built an improved Analog subsection board that replaces the ASIC's CFD and TDC with a high-performance CFD (made with discrete components) and TDC (using the CERN high-performance TDC ASIC). The improved Analog subsection board is used in a custom single-ring LSO-based TOF PET camera. The electronics system achieves a timing resolution of 60 ps FWHM. Prototype TOF detector modules are read out with the electronics system and give coincidence timing resolutions of 259 ps FWHM and 156 ps FWHM for detector modules coupled to LSO and LaBr3 crystals respectively.

High-performance electronics for time-of-flight PET systems.

PubMed

Choong, W-S; Peng, Q; Vu, C Q; Turko, B T; Moses, W W

2013-01-01

We have designed and built a high-performance readout electronics system for time-of-flight positron emission tomography (TOF PET) cameras. The electronics architecture is based on the electronics for a commercial whole-body PET camera (Siemens/CPS Cardinal electronics), modified to improve the timing performance. The fundamental contributions in the electronics that can limit the timing resolution include the constant fraction discriminator (CFD), which converts the analog electrical signal from the photo-detector to a digital signal whose leading edge is time-correlated with the input signal, and the time-to-digital converter (TDC), which provides a time stamp for the CFD output. Coincident events are identified by digitally comparing the values of the time stamps. In the Cardinal electronics, the front-end processing electronics are performed by an Analog subsection board, which has two application-specific integrated circuits (ASICs), each servicing a PET block detector module. The ASIC has a built-in CFD and TDC. We found that a significant degradation in the timing resolution comes from the ASIC's CFD and TDC. Therefore, we have designed and built an improved Analog subsection board that replaces the ASIC's CFD and TDC with a high-performance CFD (made with discrete components) and TDC (using the CERN high-performance TDC ASIC). The improved Analog subsection board is used in a custom single-ring LSO-based TOF PET camera. The electronics system achieves a timing resolution of 60 ps FWHM. Prototype TOF detector modules are read out with the electronics system and give coincidence timing resolutions of 259 ps FWHM and 156 ps FWHM for detector modules coupled to LSO and LaBr 3 crystals respectively.

High-Speed Data Acquisition and Digital Signal Processing System for PET Imaging Techniques Applied to Mammography

NASA Astrophysics Data System (ADS)

Martinez, J. D.; Benlloch, J. M.; Cerda, J.; Lerche, Ch. W.; Pavon, N.; Sebastia, A.

2004-06-01

This paper is framed into the Positron Emission Mammography (PEM) project, whose aim is to develop an innovative gamma ray sensor for early breast cancer diagnosis. Currently, breast cancer is detected using low-energy X-ray screening. However, functional imaging techniques such as PET/FDG could be employed to detect breast cancer and track disease changes with greater sensitivity. Furthermore, a small and less expensive PET camera can be utilized minimizing main problems of whole body PET. To accomplish these objectives, we are developing a new gamma ray sensor based on a newly released photodetector. However, a dedicated PEM detector requires an adequate data acquisition (DAQ) and processing system. The characterization of gamma events needs a free-running analog-to-digital converter (ADC) with sampling rates of more than 50 Ms/s and must achieve event count rates up to 10 MHz. Moreover, comprehensive data processing must be carried out to obtain event parameters necessary for performing the image reconstruction. A new generation digital signal processor (DSP) has been used to comply with these requirements. This device enables us to manage the DAQ system at up to 80 Ms/s and to execute intensive calculi over the detector signals. This paper describes our designed DAQ and processing architecture whose main features are: very high-speed data conversion, multichannel synchronized acquisition with zero dead time, a digital triggering scheme, and high throughput of data with an extensive optimization of the signal processing algorithms.

Validation of a Multimodality Flow Phantom and Its Application for Assessment of Dynamic SPECT and PET Technologies.

PubMed

Gabrani-Juma, Hanif; Clarkin, Owen J; Pourmoghaddas, Amir; Driscoll, Brandon; Wells, R Glenn; deKemp, Robert A; Klein, Ran

2017-01-01

Simple and robust techniques are lacking to assess performance of flow quantification using dynamic imaging. We therefore developed a method to qualify flow quantification technologies using a physical compartment exchange phantom and image analysis tool. We validate and demonstrate utility of this method using dynamic PET and SPECT. Dynamic image sequences were acquired on two PET/CT and a cardiac dedicated SPECT (with and without attenuation and scatter corrections) systems. A two-compartment exchange model was fit to image derived time-activity curves to quantify flow rates. Flowmeter measured flow rates (20-300 mL/min) were set prior to imaging and were used as reference truth to which image derived flow rates were compared. Both PET cameras had excellent agreement with truth ( [Formula: see text]). High-end PET had no significant bias (p > 0.05) while lower-end PET had minimal slope bias (wash-in and wash-out slopes were 1.02 and 1.01) but no significant reduction in precision relative to high-end PET (<15% vs. <14% limits of agreement, p > 0.3). SPECT (without scatter and attenuation corrections) slope biases were noted (0.85 and 1.32) and attributed to camera saturation in early time frames. Analysis of wash-out rates from non-saturated, late time frames resulted in excellent agreement with truth ( [Formula: see text], slope = 0.97). Attenuation and scatter corrections did not significantly impact SPECT performance. The proposed phantom, software and quality assurance paradigm can be used to qualify imaging instrumentation and protocols for quantification of kinetic rate parameters using dynamic imaging.

A High-Resolution Time-of-Flight Clinical PET Detection System Using a Gapless PMT-Quadrant-Sharing Method

NASA Astrophysics Data System (ADS)

Wong, Wai-Hoi; Li, Hongdi; Zhang, Yuxuan; Ramirez, Rocio; An, Shaohui; Wang, Chao; Liu, Shitao; Dong, Yun; Baghaei, Hossain

2015-10-01

We developed a high-resolution Photomultiplier-Quadrant-Sharing (PQS) PET system for human imaging. This system is made up of 24 detector panels. Each panel (bank) consists of 3 ×7 detector blocks, and each block has 16 ×16 LYSO crystals of 2.35 ×2.35 ×15.2 mm3. We used a novel detector-grinding scheme that is compatible with the PQS detector-pixel-decoding requirements to make a gapless cylindrical detector ring for maximizing detection efficiency while delivering an ultrahigh spatial-resolution for a whole-body PET camera with a ring diameter of 87 cm and axial field of view of 27.6 cm. This grinding scheme enables two adjacent gapless panels to share one row of the PMTs to extend the PQS configuration beyond one panel and thus maximize the economic benefit (in PMT usage) of the PQS design. The entire detector ring has 129,024 crystals, all of which are clearly decoded using only 576 PMTs (38-mm diameter). Thus, each PMT on average decodes 224 crystals to achieve a high crystal-pitch resolution of 2.44 mm ×2.44 mm. The detector blocks were mass-produced with our slab-sandwich-slice technique using a set of optimized mirror-film patterns (between crystals) to maximize light output and achieve high spatial and timing resolution. This detection system with time-of-flight capability was placed in a human PET/CT gantry. The reconstructed image resolution of the system was about 2.87 mm using 2D-filtered back-projection. The time-of-flight resolution was 473 ps. The preliminary images of phantoms and clinical studies presented in this work demonstrate the capability of this new PET/CT system to produce high-quality images.

Performance evaluation of a high resolution dedicated breast PET scanner

DOE Office of Scientific and Technical Information (OSTI.GOV)

García Hernández, Trinitat, E-mail: mtrinitat@eresa.com; Vicedo González, Aurora; Brualla González, Luis

2016-05-15

Purpose: Early stage breast cancers may not be visible on a whole-body PET scan. To overcome whole-body PET limitations, several dedicated breast positron emission tomography (DbPET) systems have emerged nowadays aiming to improve spatial resolution. In this work the authors evaluate the performance of a high resolution dedicated breast PET scanner (Mammi-PET, Oncovision). Methods: Global status, uniformity, sensitivity, energy, and spatial resolution were measured. Spheres of different sizes (2.5, 4, 5, and 6 mm diameter) and various 18 fluorodeoxyglucose ({sup 18}F-FDG) activity concentrations were randomly inserted in a gelatine breast phantom developed at our institution. Several lesion-to-background ratios (LBR) weremore » simulated, 5:1, 10:1, 20:1, 30:1, and 50:1. Images were reconstructed using different voxel sizes. The ability of experienced reporters to detect spheres was tested as a function of acquisition time, LBR, sphere size, and matrix reconstruction voxel size. For comparison, phantoms were scanned in the DbPET camera and in a whole body PET (WB-PET). Two patients who just underwent WB-PET/CT exams were imaged with the DbPET system and the images were compared. Results: The measured absolute peak sensitivity was 2.0%. The energy resolution was 24.0% ± 1%. The integral and differential uniformity were 10% and 6% in the total field of view (FOV) and 9% and 5% in the central FOV, respectively. The measured spatial resolution was 2.0, 1.9, and 1.7 mm in the radial, tangential, and axial directions. The system exhibited very good detectability for spheres ≥4 mm and LBR ≥10 with a sphere detection of 100% when acquisition time was set >3 min/bed. For LBR = 5 and acquisition time of 7 min the detectability was 100% for spheres of 6 mm and 75% for spheres of 5, 4, and 2.5 mm. Lesion WB-PET detectability was only comparable to the DbPET camera for lesion sizes ≥5 mm when acquisition time was >3 min and LBR > 10. Conclusions: The DbPET has a good performance for its clinical use and shows an improved resolution and lesion detectability of small lesions compared to WB-PET.« less

Commissioning and Characterization of a Dedicated High Resolution Breast PET Camera

DTIC Science & Technology

2013-07-01

coming from the PET tracer in 3 dimensions, using many 1 × 1 × 1 mm3 scintillation crystals. 2 Body: Research accomplishments as outlined in SOW 2-SA1...In addition, we won’t need to administer FDG for the sole purpose of the study: we will image with the remainder of the activity. This study will

Characterization of the LBNL PEM Camera

NASA Astrophysics Data System (ADS)

Wang, G.-C.; Huber, J. S.; Moses, W. W.; Qi, J.; Choong, W.-S.

2006-06-01

We present the tomographic images and performance measurements of the LBNL positron emission mammography (PEM) camera, a specially designed positron emission tomography (PET) camera that utilizes PET detector modules with depth of interaction measurement capability to achieve both high sensitivity and high resolution for breast cancer detection. The camera currently consists of 24 detector modules positioned as four detector banks to cover a rectangular patient port that is 8.2/spl times/6 cm/sup 2/ with a 5 cm axial extent. Each LBNL PEM detector module consists of 64 3/spl times/3/spl times/30 mm/sup 3/ LSO crystals coupled to a single photomultiplier tube (PMT) and an 8/spl times/8 silicon photodiode array (PD). The PMT provides accurate timing, the PD identifies the crystal of interaction, the sum of the PD and PMT signals (PD+PMT) provides the total energy, and the PD/(PD+PMT) ratio determines the depth of interaction. The performance of the camera has been evaluated by imaging various phantoms. The full-width-at-half-maximum (FWHM) spatial resolution changes slightly from 1.9 mm to 2.1 mm when measured at the center and corner of the field of the view, respectively, using a 6 ns coincidence timing window and a 300-750 keV energy window. With the same setup, the peak sensitivity of the camera is 1.83 kcps//spl mu/Ci.

Building blocks of a multi-layer PET with time sequence photon interaction discrimination and double Compton camera

NASA Astrophysics Data System (ADS)

Ilisie, V.; Giménez-Alventosa, V.; Moliner, L.; Sánchez, F.; González, A. J.; Rodríguez-Álvarez, M. J.; Benlloch, J. M.

2018-07-01

Current PET detectors have a very low sensitivity, of the order of a few percent. One of the reasons is the fact that Compton interactions are rejected. If an event involves multiple Compton scattering and the total deposited energy lays within the photoelectric peak, then an energy-weighted centroid is the given output for the coordinates of the reconstructed interaction point. This introduces distortion in the final reconstructed image. The aim of our work is to prove that Compton events are a very rich source of additional information as one can improve the resolution of the detector and implicitly the final reconstructed image. This could be a real breakthrough for PET detector technology as one should be able to obtain better results with less patient radiation. Using a PET as a double Compton camera, by means of Compton cone matching i.e., Compton cones coming from the same event should be compatible, is applied to discard randoms, patient scattered events and also, to perform a correct matching among events with multiple coincidences. In order to fully benefit experimentally from Compton events using monolithic scintillators a multi-layer configuration is needed and a good time-of-flight resolution.

MARS: a mouse atlas registration system based on a planar x-ray projector and an optical camera

NASA Astrophysics Data System (ADS)

Wang, Hongkai; Stout, David B.; Taschereau, Richard; Gu, Zheng; Vu, Nam T.; Prout, David L.; Chatziioannou, Arion F.

2012-10-01

This paper introduces a mouse atlas registration system (MARS), composed of a stationary top-view x-ray projector and a side-view optical camera, coupled to a mouse atlas registration algorithm. This system uses the x-ray and optical images to guide a fully automatic co-registration of a mouse atlas with each subject, in order to provide anatomical reference for small animal molecular imaging systems such as positron emission tomography (PET). To facilitate the registration, a statistical atlas that accounts for inter-subject anatomical variations was constructed based on 83 organ-labeled mouse micro-computed tomography (CT) images. The statistical shape model and conditional Gaussian model techniques were used to register the atlas with the x-ray image and optical photo. The accuracy of the atlas registration was evaluated by comparing the registered atlas with the organ-labeled micro-CT images of the test subjects. The results showed excellent registration accuracy of the whole-body region, and good accuracy for the brain, liver, heart, lungs and kidneys. In its implementation, the MARS was integrated with a preclinical PET scanner to deliver combined PET/MARS imaging, and to facilitate atlas-assisted analysis of the preclinical PET images.

MARS: a mouse atlas registration system based on a planar x-ray projector and an optical camera.

PubMed

Wang, Hongkai; Stout, David B; Taschereau, Richard; Gu, Zheng; Vu, Nam T; Prout, David L; Chatziioannou, Arion F

2012-10-07

This paper introduces a mouse atlas registration system (MARS), composed of a stationary top-view x-ray projector and a side-view optical camera, coupled to a mouse atlas registration algorithm. This system uses the x-ray and optical images to guide a fully automatic co-registration of a mouse atlas with each subject, in order to provide anatomical reference for small animal molecular imaging systems such as positron emission tomography (PET). To facilitate the registration, a statistical atlas that accounts for inter-subject anatomical variations was constructed based on 83 organ-labeled mouse micro-computed tomography (CT) images. The statistical shape model and conditional Gaussian model techniques were used to register the atlas with the x-ray image and optical photo. The accuracy of the atlas registration was evaluated by comparing the registered atlas with the organ-labeled micro-CT images of the test subjects. The results showed excellent registration accuracy of the whole-body region, and good accuracy for the brain, liver, heart, lungs and kidneys. In its implementation, the MARS was integrated with a preclinical PET scanner to deliver combined PET/MARS imaging, and to facilitate atlas-assisted analysis of the preclinical PET images.

Comparison of Monte Carlo simulated and measured performance parameters of miniPET scanner

NASA Astrophysics Data System (ADS)

Kis, S. A.; Emri, M.; Opposits, G.; Bükki, T.; Valastyán, I.; Hegyesi, Gy.; Imrek, J.; Kalinka, G.; Molnár, J.; Novák, D.; Végh, J.; Kerek, A.; Trón, L.; Balkay, L.

2007-02-01

In vivo imaging of small laboratory animals is a valuable tool in the development of new drugs. For this purpose, miniPET, an easy to scale modular small animal PET camera has been developed at our institutes. The system has four modules, which makes it possible to rotate the whole detector system around the axis of the field of view. Data collection and image reconstruction are performed using a data acquisition (DAQ) module with Ethernet communication facility and a computer cluster of commercial PCs. Performance tests were carried out to determine system parameters, such as energy resolution, sensitivity and noise equivalent count rate. A modified GEANT4-based GATE Monte Carlo software package was used to simulate PET data analogous to those of the performance measurements. GATE was run on a Linux cluster of 10 processors (64 bit, Xeon with 3.0 GHz) and controlled by a SUN grid engine. The application of this special computer cluster reduced the time necessary for the simulations by an order of magnitude. The simulated energy spectra, maximum rate of true coincidences and sensitivity of the camera were in good agreement with the measured parameters.

Development of a novel depth of interaction PET detector using highly multiplexed G-APD cross-strip encoding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kolb, A., E-mail: armin.kolb@med.uni-tuebingen.de; Parl, C.; Liu, C. C.

Purpose: The aim of this study was to develop a prototype PET detector module for a combined small animal positron emission tomography and magnetic resonance imaging (PET/MRI) system. The most important factor for small animal imaging applications is the detection sensitivity of the PET camera, which can be optimized by utilizing longer scintillation crystals. At the same time, small animal PET systems must yield a high spatial resolution. The measured object is very close to the PET detector because the bore diameter of a high field animal MR scanner is limited. When used in combination with long scintillation crystals, thesemore » small-bore PET systems generate parallax errors that ultimately lead to a decreased spatial resolution. Thus, we developed a depth of interaction (DoI) encoding PET detector module that has a uniform spatial resolution across the whole field of view (FOV), high detection sensitivity, compactness, and insensitivity to magnetic fields. Methods: The approach was based on Geiger mode avalanche photodiode (G-APD) detectors with cross-strip encoding. The number of readout channels was reduced by a factor of 36 for the chosen block elements. Two 12 × 2 G-APD strip arrays (25μm cells) were placed perpendicular on each face of a 12 × 12 lutetium oxyorthosilicate crystal block with a crystal size of 1.55 × 1.55 × 20 mm. The strip arrays were multiplexed into two channels and used to calculate the x, y coordinates for each array and the deposited energy. The DoI was measured in step sizes of 1.8 mm by a collimated {sup 18}F source. The coincident resolved time (CRT) was analyzed at all DoI positions by acquiring the waveform for each event and applying a digital leading edge discriminator. Results: All 144 crystals were well resolved in the crystal flood map. The average full width half maximum (FWHM) energy resolution of the detector was 12.8% ± 1.5% with a FWHM CRT of 1.14 ± 0.02 ns. The average FWHM DoI resolution over 12 crystals was 2.90 ± 0.15 mm. Conclusions: The novel DoI PET detector, which is based on strip G-APD arrays, yielded a DoI resolution of 2.9 mm and excellent timing and energy resolution. Its high multiplexing factor reduces the number of electronic channels. Thus, this cross-strip approach enables low-cost, high-performance PET detectors for dedicated small animal PET and PET/MRI and potentially clinical PET/MRI systems.« less

Application of Timepix3 based CdTe spectral sensitive photon counting detector for PET imaging

NASA Astrophysics Data System (ADS)

Turecek, Daniel; Jakubek, Jan; Trojanova, Eliska; Sefc, Ludek; Kolarova, Vera

2018-07-01

Positron emission tomography (PET) is a nuclear medicine functional imaging technique. It is used in clinical oncology (medical imaging of tumors and the search for metastases), and pre-clinical studies using animals. PET uses small amounts of radioactive materials (radiotracers) and a special photon sensitive camera. Most of these cameras use scintillators with photomultipliers as detectors. However, these detectors have limited energy sensitivity and large pixels. Therefore, the false signal caused by a scattering poses a significant problem. In this work we study properties of position, energy and time sensitive semiconductor detector of Timepix3 type and its applicability for PET measurements. This work presents an initial study and evaluation of two Timepix3 detectors with 2 mm thick CdTe sensors used in simplified geometry for PET imaging. The study is performed on 2 samples - a capillary tube and a cylindrical plexiglass phantom with cavities. Both samples are filled with fluodeoxyglucose (FDG) solution that is used as a radiotracer. The Timepix3 offers better properties compared to conventional detectors - high granularity (55 μm pixel pitch), good energy resolution (1 keV at 60 keV) and sufficient time resolution (1.6 ns). The spectral sensitivity of Timepix3 together with coincidence/anticoincidence technique allows for significant reduction of background signal caused by Compton scattering and internal X-ray fluorescence of Cd and Te.

Dosage optimization in positron emission tomography: state-of-the-art methods and future prospects

PubMed Central

Karakatsanis, Nicolas A; Fokou, Eleni; Tsoumpas, Charalampos

2015-01-01

Positron emission tomography (PET) is widely used nowadays for tumor staging and therapy response in the clinic. However, average PET radiation exposure has increased due to higher PET utilization. This study aims to review state-of-the-art PET tracer dosage optimization methods after accounting for the effects of human body attenuation and scan protocol parameters on the counting rate. In particular, the relationship between the noise equivalent count rate (NECR) and the dosage (NECR-dosage curve) for a range of clinical PET systems and body attenuation sizes will be systematically studied to prospectively estimate the minimum dosage required for sufficiently high NECR. The optimization criterion can be determined either as a function of the peak of the NECR-dosage curve or as a fixed NECR score when NECR uniformity across a patient population is important. In addition, the systematic NECR assessments within a controllable environment of realistic simulations and phantom experiments can lead to a NECR-dosage response model, capable of predicting the optimal dosage for every individual PET scan. Unlike conventional guidelines suggesting considerably large dosage levels for obese patients, NECR-based optimization recommends: i) moderate dosage to achieve 90% of peak NECR for obese patients, ii) considerable dosage reduction for slimmer patients such that uniform NECR is attained across the patient population, and iii) prolongation of scans for PET/MR protocols, where longer PET acquisitions are affordable due to lengthy MR sequences, with motion compensation becoming important then. Finally, the need for continuous adaptation of dosage optimization to emerging technologies will be discussed. PMID:26550543

Potential clinical impact of radionuclide imaging technologies: highlights of the ITBS 2003 meeting

NASA Astrophysics Data System (ADS)

Itti, Roland

2004-07-01

Radiopharmaceuticals are major determinants of progress in Nuclear Medicine. Besides 18FDG, the most common PET tracer, several other molecules are under evaluation, such as 18F-fluoride for bone studies, numerous ligands for neurotransmission, 18F-DOPA for neuro-endocrine tumors or generator produced 68Ga-peptides for various cancers. Nuclear medicine gradually changes for "molecular imaging" and medical imaging, which was at the beginning mainly anatomic, has progressed in the direction of functional and metabolic imaging. The present challenge is to achieve some degree of "in vivo" biochemistry or even histology or genetics. The importance of anatomic/functional image fusion justifies the development of combined PET-CT instrumentation, whose objectives have to be discussed in terms of anatomical landmarks and/or additional clinical information. The question of "hard" or "soft" image co-registration remains open, involving not only CT, but also SPECT or MRI. Development of dedicated imaging devices, whether single photon or positron, is of major interest for breast imaging, allowing optimal imaging conditions, with results definitely superior to classical gamma-cameras or PET. The patient population concerned with scintimammography is still controversial, as well as the imaging modalities: FDG or sestaMIBI, planar or tomographic, scintillators or semi-conductors, and the research field remains open. This is also valid for external or per-operative probe systems for tumor or lymph nodes localization.

Clinical trials of the prototype Rutherford Appleton Laboratory MWPC positron camera at the Royal Marsden Hospital

NASA Astrophysics Data System (ADS)

Flower, M. A.; Ott, R. J.; Webb, S.; Leach, M. O.; Marsden, P. K.; Clack, R.; Khan, O.; Batty, V.; McCready, V. R.; Bateman, J. E.

1988-06-01

Two clinical trials of the prototype RAL multiwire proportional chamber (MWPC) positron camera were carried out prior to the development of a clinical system with large-area detectors. During the first clinical trial, the patient studies included skeletal imaging using 18F, imaging of brain glucose metabolism using 18F FDG, bone marrow imaging using 52Fe citrate and thyroid imaging with Na 124I. Longitudinal tomograms were produced from the limited-angle data acquisition from the static detectors. During the second clinical trial, transaxial, coronal and sagittal images were produced from the multiview data acquisition. A more detailed thyroid study was performed in which the volume of the functioning thyroid tissue was obtained from the 3D PET image and this volume was used in estimating the radiation dose achieved during radioiodine therapy of patients with thyrotoxicosis. Despite the small field of view of the prototype camera, and the use of smaller than usual amounts of activity administered, the PET images were in most cases comparable with, and in a few cases visually better than, the equivalent planar view using a state-of-the-art gamma camera with a large field of view and routine radiopharmaceuticals.

Marker-less multi-frame motion tracking and compensation in PET-brain imaging

NASA Astrophysics Data System (ADS)

Lindsay, C.; Mukherjee, J. M.; Johnson, K.; Olivier, P.; Song, X.; Shao, L.; King, M. A.

2015-03-01

In PET brain imaging, patient motion can contribute significantly to the degradation of image quality potentially leading to diagnostic and therapeutic problems. To mitigate the image artifacts resulting from patient motion, motion must be detected and tracked then provided to a motion correction algorithm. Existing techniques to track patient motion fall into one of two categories: 1) image-derived approaches and 2) external motion tracking (EMT). Typical EMT requires patients to have markers in a known pattern on a rigid too attached to their head, which are then tracked by expensive and bulky motion tracking camera systems or stereo cameras. This has made marker-based EMT unattractive for routine clinical application. Our main contributions are the development of a marker-less motion tracking system that uses lowcost, small depth-sensing cameras which can be installed in the bore of the imaging system. Our motion tracking system does not require anything to be attached to the patient and can track the rigid transformation (6-degrees of freedom) of the patient's head at a rate 60 Hz. We show that our method can not only be used in with Multi-frame Acquisition (MAF) PET motion correction, but precise timing can be employed to determine only the necessary frames needed for correction. This can speeds up reconstruction by eliminating the unnecessary subdivision of frames.

Dose Optimization in TOF-PET/MR Compared to TOF-PET/CT

PubMed Central

Queiroz, Marcelo A.; Delso, Gaspar; Wollenweber, Scott; Deller, Timothy; Zeimpekis, Konstantinos; Huellner, Martin; de Galiza Barbosa, Felipe; von Schulthess, Gustav; Veit-Haibach, Patrick

2015-01-01

Purpose To evaluate the possible activity reduction in FDG-imaging in a Time-of-Flight (TOF) PET/MR, based on cross-evaluation of patient-based NECR (noise equivalent count rate) measurements in PET/CT, cross referencing with phantom-based NECR curves as well as initial evaluation of TOF-PET/MR with reduced activity. Materials and Methods A total of 75 consecutive patients were evaluated in this study. PET/CT imaging was performed on a PET/CT (time-of-flight (TOF) Discovery D 690 PET/CT). Initial PET/MR imaging was performed on a newly available simultaneous TOF-PET/MR (Signa PET/MR). An optimal NECR for diagnostic purposes was defined in clinical patients (NECRP) in PET/CT. Subsequent optimal activity concentration at the acquisition time ([A]0) and target NECR (NECRT) were obtained. These data were used to predict the theoretical FDG activity requirement of the new TOF-PET/MR system. Twenty-five initial patients were acquired with (retrospectively reconstructed) different imaging times equivalent for different activities on the simultaneous PET/MR for the evaluation of clinically realistic FDG-activities. Results The obtained values for NECRP, [A]0 and NECRT were 114.6 (± 14.2) kcps (Kilocounts per second), 4.0 (± 0.7) kBq/mL and 45 kcps, respectively. Evaluating the NECRT together with the phantom curve of the TOF-PET/MR device, the theoretical optimal activity concentration was found to be approximately 1.3 kBq/mL, which represents 35% of the activity concentration required by the TOF-PET/CT. Initial evaluation on patients in the simultaneous TOF-PET/MR shows clinically realistic activities of 1.8 kBq/mL, which represent 44% of the required activity. Conclusion The new TOF-PET/MR device requires significantly less activity to generate PET-images with good-to-excellent image quality, due to improvements in detector geometry and detector technologies. The theoretically achievable dose reduction accounts for up to 65% but cannot be fully translated into clinical routine based on the coils within the FOV and MR-sequences applied at the same time. The clinically realistic reduction in activity is slightly more than 50%. Further studies in a larger number of patients are needed to confirm our findings. PMID:26147919

First validation of myocardial flow reserve assessed by dynamic 99mTc-sestamibi CZT-SPECT camera: head to head comparison with 15O-water PET and fractional flow reserve in patients with suspected coronary artery disease. The WATERDAY study.

PubMed

Agostini, Denis; Roule, Vincent; Nganoa, Catherine; Roth, Nathaniel; Baavour, Raphael; Parienti, Jean-Jacques; Beygui, Farzin; Manrique, Alain

2018-07-01

We assessed the feasibility of myocardial blood flow (MBF) and flow reserve (MFR) estimation using dynamic SPECT with a novel CZT camera in patients with stable CAD, in comparison with 15 O-water PET and fractional flow reserve (FFR). Thirty patients were prospectively included and underwent FFR measurements in the main coronary arteries (LAD, LCx, RCA). A stenosis ≥50% was considered obstructive and a FFR abnormal if ≤0.8. All patients underwent a dynamic rest/stress 99m Tc-sestamibi CZT-SPECT and 15 O-water PET for MBF and MFR calculation. Net retention kinetic modeling was applied to SPECT data to estimate global uptake values, and MBF was derived using Leppo correction. Ischemia by PET and CZT-SPECT was considered present if MFR was lower than 2 and 2.1, respectively. CZT-SPECT yielded higher stress and rest MBF compared to PET for global and LAD and LCx territories, but not in RCA territory. MFR was similar in global and each vessel territory for both modalities. The sensitivity, specificity, accuracy, positive and negative predictive value of CZT-SPECT were, respectively, 83.3, 95.8, 93.3, 100 and 85.7% for the detection of ischemia and 58.3, 84.6, 81.1, 36.8 and 93% for the detection of hemodynamically significant stenosis (FFR ≤ 0.8). Dynamic 99m Tc-sestamibi CZT-SPECT was technically feasible and provided similar MFR compared to 15 O-water PET and high diagnostic value for detecting impaired MFR and abnormal FFR in patients with stable CAD.

Markerless rat head motion tracking using structured light for brain PET imaging of unrestrained awake small animals

NASA Astrophysics Data System (ADS)

Miranda, Alan; Staelens, Steven; Stroobants, Sigrid; Verhaeghe, Jeroen

2017-03-01

Preclinical positron emission tomography (PET) imaging in small animals is generally performed under anesthesia to immobilize the animal during scanning. More recently, for rat brain PET studies, methods to perform scans of unrestrained awake rats are being developed in order to avoid the unwanted effects of anesthesia on the brain response. Here, we investigate the use of a projected structure stereo camera to track the motion of the rat head during the PET scan. The motion information is then used to correct the PET data. The stereo camera calculates a 3D point cloud representation of the scene and the tracking is performed by point cloud matching using the iterative closest point algorithm. The main advantage of the proposed motion tracking is that no intervention, e.g. for marker attachment, is needed. A manually moved microDerenzo phantom experiment and 3 awake rat [18F]FDG experiments were performed to evaluate the proposed tracking method. The tracking accuracy was 0.33 mm rms. After motion correction image reconstruction, the microDerenzo phantom was recovered albeit with some loss of resolution. The reconstructed FWHM of the 2.5 and 3 mm rods increased with 0.94 and 0.51 mm respectively in comparison with the motion-free case. In the rat experiments, the average tracking success rate was 64.7%. The correlation of relative brain regional [18F]FDG uptake between the anesthesia and awake scan reconstructions was increased from on average 0.291 (not significant) before correction to 0.909 (p  <  0.0001) after motion correction. Markerless motion tracking using structured light can be successfully used for tracking of the rat head for motion correction in awake rat PET scans.

Evidence for the use PET for radiation therapy planning in patients with cervical cancer: a systematic review.

PubMed

Salem, A; Salem, A F; Al-Ibraheem, A; Lataifeh, I; Almousa, A; Jaradat, I

2011-01-01

In recent years, the role of positron emission tomography (PET) in the staging and management of gynecological cancers has been increasing. The aim of this study was to systematically review the role of PET in radiotherapy planning and brachytherapy treatment optimization in patients with cervical cancer. Systematic literature review. Systematic review of relevant literature addressing the utilization of PET and/or PET-computed tomography (CT) in external-beam radiotherapy planning and brachytherapy treatment optimization. We performed an extensive PubMed database search on 20 April 2011. Nineteen studies, including 759 patients, formed the basis of this systematic review. PET/ PET-CT is the most sensitive imaging modality for detecting nodal metastases in patients with cervical cancer and has been shown to impact external-beam radiotherapy planning by modifying the treatment field and customizing the radiation dose. This particularly applies to detection of previously uncovered para-aortic and inguinal nodal metastases. Furthermore, PET/ PET-CT guided intensity-modulated radiation therapy (IMRT) allows delivery of higher doses of radiation to the primary tumor, if brachytherapy is unsuitable, and to grossly involved nodal disease while minimizing treatment-related toxicity. PET/ PET-CT based brachytherapy optimization allows improved tumor-volume dose distribution and detailed 3D dosimetric evaluation of risk organs. Sequential PET/ PET-CT imaging performed during the course of brachytherapy form the basis of “adaptive” brachytherapy in cervical cancer. This review demonstrates the effectiveness of pretreatment PET/ PET-CT in cervical cancer patients treated by radiotherapy. Further prospective studies are required to define the group of patients who would benefit the most from this procedure.

Imaging and dosimetric errors in 4D PET/CT-guided radiotherapy from patient-specific respiratory patterns: a dynamic motion phantom end-to-end study

NASA Astrophysics Data System (ADS)

Bowen, S. R.; Nyflot, M. J.; Herrmann, C.; Groh, C. M.; Meyer, J.; Wollenweber, S. D.; Stearns, C. W.; Kinahan, P. E.; Sandison, G. A.

2015-05-01

Effective positron emission tomography / computed tomography (PET/CT) guidance in radiotherapy of lung cancer requires estimation and mitigation of errors due to respiratory motion. An end-to-end workflow was developed to measure patient-specific motion-induced uncertainties in imaging, treatment planning, and radiation delivery with respiratory motion phantoms and dosimeters. A custom torso phantom with inserts mimicking normal lung tissue and lung lesion was filled with [18F]FDG. The lung lesion insert was driven by six different patient-specific respiratory patterns or kept stationary. PET/CT images were acquired under motionless ground truth, tidal breathing motion-averaged (3D), and respiratory phase-correlated (4D) conditions. Target volumes were estimated by standardized uptake value (SUV) thresholds that accurately defined the ground-truth lesion volume. Non-uniform dose-painting plans using volumetrically modulated arc therapy were optimized for fixed normal lung and spinal cord objectives and variable PET-based target objectives. Resulting plans were delivered to a cylindrical diode array at rest, in motion on a platform driven by the same respiratory patterns (3D), or motion-compensated by a robotic couch with an infrared camera tracking system (4D). Errors were estimated relative to the static ground truth condition for mean target-to-background (T/Bmean) ratios, target volumes, planned equivalent uniform target doses, and 2%-2 mm gamma delivery passing rates. Relative to motionless ground truth conditions, PET/CT imaging errors were on the order of 10-20%, treatment planning errors were 5-10%, and treatment delivery errors were 5-30% without motion compensation. Errors from residual motion following compensation methods were reduced to 5-10% in PET/CT imaging, <5% in treatment planning, and <2% in treatment delivery. We have demonstrated that estimation of respiratory motion uncertainty and its propagation from PET/CT imaging to RT planning, and RT delivery under a dose painting paradigm is feasible within an integrated respiratory motion phantom workflow. For a limited set of cases, the magnitude of errors was comparable during PET/CT imaging and treatment delivery without motion compensation. Errors were moderately mitigated during PET/CT imaging and significantly mitigated during RT delivery with motion compensation. This dynamic motion phantom end-to-end workflow provides a method for quality assurance of 4D PET/CT-guided radiotherapy, including evaluation of respiratory motion compensation methods during imaging and treatment delivery.

Imaging and dosimetric errors in 4D PET/CT-guided radiotherapy from patient-specific respiratory patterns: a dynamic motion phantom end-to-end study.

PubMed

Bowen, S R; Nyflot, M J; Herrmann, C; Groh, C M; Meyer, J; Wollenweber, S D; Stearns, C W; Kinahan, P E; Sandison, G A

2015-05-07

Effective positron emission tomography / computed tomography (PET/CT) guidance in radiotherapy of lung cancer requires estimation and mitigation of errors due to respiratory motion. An end-to-end workflow was developed to measure patient-specific motion-induced uncertainties in imaging, treatment planning, and radiation delivery with respiratory motion phantoms and dosimeters. A custom torso phantom with inserts mimicking normal lung tissue and lung lesion was filled with [(18)F]FDG. The lung lesion insert was driven by six different patient-specific respiratory patterns or kept stationary. PET/CT images were acquired under motionless ground truth, tidal breathing motion-averaged (3D), and respiratory phase-correlated (4D) conditions. Target volumes were estimated by standardized uptake value (SUV) thresholds that accurately defined the ground-truth lesion volume. Non-uniform dose-painting plans using volumetrically modulated arc therapy were optimized for fixed normal lung and spinal cord objectives and variable PET-based target objectives. Resulting plans were delivered to a cylindrical diode array at rest, in motion on a platform driven by the same respiratory patterns (3D), or motion-compensated by a robotic couch with an infrared camera tracking system (4D). Errors were estimated relative to the static ground truth condition for mean target-to-background (T/Bmean) ratios, target volumes, planned equivalent uniform target doses, and 2%-2 mm gamma delivery passing rates. Relative to motionless ground truth conditions, PET/CT imaging errors were on the order of 10-20%, treatment planning errors were 5-10%, and treatment delivery errors were 5-30% without motion compensation. Errors from residual motion following compensation methods were reduced to 5-10% in PET/CT imaging, <5% in treatment planning, and <2% in treatment delivery. We have demonstrated that estimation of respiratory motion uncertainty and its propagation from PET/CT imaging to RT planning, and RT delivery under a dose painting paradigm is feasible within an integrated respiratory motion phantom workflow. For a limited set of cases, the magnitude of errors was comparable during PET/CT imaging and treatment delivery without motion compensation. Errors were moderately mitigated during PET/CT imaging and significantly mitigated during RT delivery with motion compensation. This dynamic motion phantom end-to-end workflow provides a method for quality assurance of 4D PET/CT-guided radiotherapy, including evaluation of respiratory motion compensation methods during imaging and treatment delivery.

Imaging and dosimetric errors in 4D PET/CT-guided radiotherapy from patient-specific respiratory patterns: a dynamic motion phantom end-to-end study

PubMed Central

Bowen, S R; Nyflot, M J; Hermann, C; Groh, C; Meyer, J; Wollenweber, S D; Stearns, C W; Kinahan, P E; Sandison, G A

2015-01-01

Effective positron emission tomography/computed tomography (PET/CT) guidance in radiotherapy of lung cancer requires estimation and mitigation of errors due to respiratory motion. An end-to-end workflow was developed to measure patient-specific motion-induced uncertainties in imaging, treatment planning, and radiation delivery with respiratory motion phantoms and dosimeters. A custom torso phantom with inserts mimicking normal lung tissue and lung lesion was filled with [18F]FDG. The lung lesion insert was driven by 6 different patient-specific respiratory patterns or kept stationary. PET/CT images were acquired under motionless ground truth, tidal breathing motion-averaged (3D), and respiratory phase-correlated (4D) conditions. Target volumes were estimated by standardized uptake value (SUV) thresholds that accurately defined the ground-truth lesion volume. Non-uniform dose-painting plans using volumetrically modulated arc therapy (VMAT) were optimized for fixed normal lung and spinal cord objectives and variable PET-based target objectives. Resulting plans were delivered to a cylindrical diode array at rest, in motion on a platform driven by the same respiratory patterns (3D), or motion-compensated by a robotic couch with an infrared camera tracking system (4D). Errors were estimated relative to the static ground truth condition for mean target-to-background (T/Bmean) ratios, target volumes, planned equivalent uniform target doses (EUD), and 2%-2mm gamma delivery passing rates. Relative to motionless ground truth conditions, PET/CT imaging errors were on the order of 10–20%, treatment planning errors were 5–10%, and treatment delivery errors were 5–30% without motion compensation. Errors from residual motion following compensation methods were reduced to 5–10% in PET/CT imaging, < 5% in treatment planning, and < 2% in treatment delivery. We have demonstrated that estimation of respiratory motion uncertainty and its propagation from PET/CT imaging to RT planning, and RT delivery under a dose painting paradigm is feasible within an integrated respiratory motion phantom workflow. For a limited set of cases, the magnitude of errors was comparable during PET/CT imaging and treatment delivery without motion compensation. Errors were moderately mitigated during PET/CT imaging and significantly mitigated during RT delivery with motion compensation. This dynamic motion phantom end-to-end workflow provides a method for quality assurance of 4D PET/CT-guided radiotherapy, including evaluation of respiratory motion compensation methods during imaging and treatment delivery. PMID:25884892

Optimization of a LSO-Based Detector Module for Time-of-Flight PET

NASA Astrophysics Data System (ADS)

Moses, W. W.; Janecek, M.; Spurrier, M. A.; Szupryczynski, P.; Choong, W.-S.; Melcher, C. L.; Andreaco, M.

2010-06-01

We have explored methods for optimizing the timing resolution of an LSO-based detector module for a single-ring, “demonstration” time-of-flight PET camera. By maximizing the area that couples the scintillator to the PMT and minimizing the average path length that the scintillation photons travel, a single detector timing resolution of 218 ps fwhm is measured, which is considerably better than the 385 ps fwhm obtained by commercial LSO or LYSO TOF detector modules. We explored different surface treatments (saw-cut, mechanically polished, and chemically etched) and reflector materials (Teflon tape, ESR, Lumirror, Melinex, white epoxy, and white paint), and found that for our geometry, a chemically etched surface had 5% better timing resolution than the saw-cut or mechanically polished surfaces, and while there was little dependence on the timing resolution between the various reflectors, white paint and white epoxy were a few percent better. Adding co-dopants to LSO shortened the decay time from 40 ns to 30 ns but maintained the same or higher total light output. This increased the initial photoelectron rate and so improved the timing resolution by 15%. Using photomultiplier tubes with higher quantum efficiency (blue sensitivity index of 13.5 rather than 12) improved the timing resolution by an additional 5%. By choosing the optimum surface treatment (chemically etched), reflector (white paint), LSO composition (co-doped), and PMT (13.5 blue sensitivity index), the coincidence timing resolution of our detector module was reduced from 309 ps to 220 ps fwhm.

Dynamic PET of human liver inflammation: impact of kinetic modeling with optimization-derived dual-blood input function.

PubMed

Wang, Guobao; Corwin, Michael T; Olson, Kristin A; Badawi, Ramsey D; Sarkar, Souvik

2018-05-30

The hallmark of nonalcoholic steatohepatitis is hepatocellular inflammation and injury in the setting of hepatic steatosis. Recent work has indicated that dynamic 18F-FDG PET with kinetic modeling has the potential to assess hepatic inflammation noninvasively, while static FDG-PET did not show a promise. Because the liver has dual blood supplies, kinetic modeling of dynamic liver PET data is challenging in human studies. The objective of this study is to evaluate and identify a dual-input kinetic modeling approach for dynamic FDG-PET of human liver inflammation. Fourteen human patients with nonalcoholic fatty liver disease were included in the study. Each patient underwent one-hour dynamic FDG-PET/CT scan and had liver biopsy within six weeks. Three models were tested for kinetic analysis: traditional two-tissue compartmental model with an image-derived single-blood input function (SBIF), model with population-based dual-blood input function (DBIF), and modified model with optimization-derived DBIF through a joint estimation framework. The three models were compared using Akaike information criterion (AIC), F test and histopathologic inflammation reference. The results showed that the optimization-derived DBIF model improved the fitting of liver time activity curves and achieved lower AIC values and higher F values than the SBIF and population-based DBIF models in all patients. The optimization-derived model significantly increased FDG K1 estimates by 101% and 27% as compared with traditional SBIF and population-based DBIF. K1 by the optimization-derived model was significantly associated with histopathologic grades of liver inflammation while the other two models did not provide a statistical significance. In conclusion, modeling of DBIF is critical for kinetic analysis of dynamic liver FDG-PET data in human studies. The optimization-derived DBIF model is more appropriate than SBIF and population-based DBIF for dynamic FDG-PET of liver inflammation. © 2018 Institute of Physics and Engineering in Medicine.

[Business administration of PET facilities: a cost analysis of three facilities utilizing delivery FDG].

PubMed

Mitsutake, Naohiro; Oku, Shinya; Fujii, Ryo; Furui, Yuji; Yasunaga, Hideo

2008-05-01

PET (positron emission tomography) has been proved to be a powerful imaging tool in clinical oncology. The number of PET facilities in Japan has remarkably increased over the last decade. Furthermore, the approval of delivery FDG in 2005 resulted in a tremendous expansion of the PET institutions without a cyclotron facility. The aim of this study was to conduct a cost analysis of PET institutions that utilized delivery FDG. Three PET facilities using delivery FDG were investigated about the costs for PET service. Fixed costs included depreciation costs for construction and medical equipments such as positron camera. Variable costs consisted of costs for medical materials including delivery FDG. The break-even point was analyzed in each of three institutions. In the three hospitals (A, B and C), the annual number of PET scan was 1,591, 1,637 and 914, while cost per scan was accounted as yen 110,262, yen 111,091, and yen 134,192, respectively. The break-even point was calculated to be 2,583, 2,679 and 2,081, respectively. PET facilities utilizing delivery FDG seemed to have difficulty in business administration. Such a situation suggests the possibility that the current supply of PET facilities might exceed actual demand for the service. The efficiency of resource allocation should be taken into consideration in the future health service researches on PET.

Positron emission particle tracking using a modular positron camera

NASA Astrophysics Data System (ADS)

Parker, D. J.; Leadbeater, T. W.; Fan, X.; Hausard, M. N.; Ingram, A.; Yang, Z.

2009-06-01

The technique of positron emission particle tracking (PEPT), developed at Birmingham in the early 1990s, enables a radioactively labelled tracer particle to be accurately tracked as it moves between the detectors of a "positron camera". In 1999 the original Birmingham positron camera, which consisted of a pair of MWPCs, was replaced by a system comprising two NaI(Tl) gamma camera heads operating in coincidence. This system has been successfully used for PEPT studies of a wide range of granular and fluid flow processes. More recently a modular positron camera has been developed using a number of the bismuth germanate (BGO) block detectors from standard PET scanners (CTI ECAT 930 and 950 series). This camera has flexible geometry, is transportable, and is capable of delivering high data rates. This paper presents simple models of its performance, and initial experience of its use in a range of geometries and applications.

Optimal transformations leading to normal distributions of positron emission tomography standardized uptake values.

PubMed

Scarpelli, Matthew; Eickhoff, Jens; Cuna, Enrique; Perlman, Scott; Jeraj, Robert

2018-01-30

The statistical analysis of positron emission tomography (PET) standardized uptake value (SUV) measurements is challenging due to the skewed nature of SUV distributions. This limits utilization of powerful parametric statistical models for analyzing SUV measurements. An ad-hoc approach, which is frequently used in practice, is to blindly use a log transformation, which may or may not result in normal SUV distributions. This study sought to identify optimal transformations leading to normally distributed PET SUVs extracted from tumors and assess the effects of therapy on the optimal transformations. The optimal transformation for producing normal distributions of tumor SUVs was identified by iterating the Box-Cox transformation parameter (λ) and selecting the parameter that maximized the Shapiro-Wilk P-value. Optimal transformations were identified for tumor SUV max distributions at both pre and post treatment. This study included 57 patients that underwent 18 F-fluorodeoxyglucose ( 18 F-FDG) PET scans (publically available dataset). In addition, to test the generality of our transformation methodology, we included analysis of 27 patients that underwent 18 F-Fluorothymidine ( 18 F-FLT) PET scans at our institution. After applying the optimal Box-Cox transformations, neither the pre nor the post treatment 18 F-FDG SUV distributions deviated significantly from normality (P  >  0.10). Similar results were found for 18 F-FLT PET SUV distributions (P  >  0.10). For both 18 F-FDG and 18 F-FLT SUV distributions, the skewness and kurtosis increased from pre to post treatment, leading to a decrease in the optimal Box-Cox transformation parameter from pre to post treatment. There were types of distributions encountered for both 18 F-FDG and 18 F-FLT where a log transformation was not optimal for providing normal SUV distributions. Optimization of the Box-Cox transformation, offers a solution for identifying normal SUV transformations for when the log transformation is insufficient. The log transformation is not always the appropriate transformation for producing normally distributed PET SUVs.

Optimal transformations leading to normal distributions of positron emission tomography standardized uptake values

NASA Astrophysics Data System (ADS)

Scarpelli, Matthew; Eickhoff, Jens; Cuna, Enrique; Perlman, Scott; Jeraj, Robert

2018-02-01

The statistical analysis of positron emission tomography (PET) standardized uptake value (SUV) measurements is challenging due to the skewed nature of SUV distributions. This limits utilization of powerful parametric statistical models for analyzing SUV measurements. An ad-hoc approach, which is frequently used in practice, is to blindly use a log transformation, which may or may not result in normal SUV distributions. This study sought to identify optimal transformations leading to normally distributed PET SUVs extracted from tumors and assess the effects of therapy on the optimal transformations. Methods. The optimal transformation for producing normal distributions of tumor SUVs was identified by iterating the Box-Cox transformation parameter (λ) and selecting the parameter that maximized the Shapiro-Wilk P-value. Optimal transformations were identified for tumor SUVmax distributions at both pre and post treatment. This study included 57 patients that underwent 18F-fluorodeoxyglucose (18F-FDG) PET scans (publically available dataset). In addition, to test the generality of our transformation methodology, we included analysis of 27 patients that underwent 18F-Fluorothymidine (18F-FLT) PET scans at our institution. Results. After applying the optimal Box-Cox transformations, neither the pre nor the post treatment 18F-FDG SUV distributions deviated significantly from normality (P  >  0.10). Similar results were found for 18F-FLT PET SUV distributions (P  >  0.10). For both 18F-FDG and 18F-FLT SUV distributions, the skewness and kurtosis increased from pre to post treatment, leading to a decrease in the optimal Box-Cox transformation parameter from pre to post treatment. There were types of distributions encountered for both 18F-FDG and 18F-FLT where a log transformation was not optimal for providing normal SUV distributions. Conclusion. Optimization of the Box-Cox transformation, offers a solution for identifying normal SUV transformations for when the log transformation is insufficient. The log transformation is not always the appropriate transformation for producing normally distributed PET SUVs.

PET AND SPECT STUDIES IN CHILDREN WITH HEMISPHERIC LOW-GRADE GLIOMAS

PubMed Central

Juhász, Csaba; Bosnyák, Edit

2016-01-01

Molecular imaging is playing an increasing role in the pre-treatment evaluation of low-grade gliomas. While glucose positron emission tomography (PET) can be helpful to differentiate low-grade from high-grade tumors, PET imaging with amino acid radiotracers has several advantages, such as better differentiation between tumors and non-tumorous lesions, optimized biopsy targeting and improved detection of tumor recurrence. This review provides a brief overview of single photon emission computed tomography (SPECT) studies followed by a more detailed review of clinical applications of glucose and amino acid PET imaging in low-grade hemispheric gliomas. We discuss key differences in the performance of the most commonly utilized PET radiotracers and highlight the advantage of PET/MRI fusion to obtain optimal information about tumor extent, heterogeneity and metabolism. Recent data also suggest that simultaneous acquisition of PET/MR images and the combination of advanced MRI techniques with quantitative PET can further improve the pre- and post-treatment evaluation of pediatric brain tumors. PMID:27659825

PET and SPECT studies in children with hemispheric low-grade gliomas.

PubMed

Juhász, Csaba; Bosnyák, Edit

2016-10-01

Molecular imaging is playing an increasing role in the pretreatment evaluation of low-grade gliomas. While glucose positron emission tomography (PET) can be helpful to differentiate low-grade from high-grade tumors, PET imaging with amino acid radiotracers has several advantages, such as better differentiation between tumors and non-tumorous lesions, optimized biopsy targeting, and improved detection of tumor recurrence. This review provides a brief overview of single-photon emission computed tomography (SPECT) studies followed by a more detailed review of the clinical applications of glucose and amino acid PET imaging in low-grade hemispheric gliomas. We discuss key differences in the performance of the most commonly utilized PET radiotracers and highlight the advantage of PET/MRI fusion to obtain optimal information about tumor extent, heterogeneity, and metabolism. Recent data also suggest that simultaneous acquisition of PET/MR images and the combination of advanced MRI techniques with quantitative PET can further improve the pretreatment and post-treatment evaluation of pediatric brain tumors.

Motion and Emotional Behavior Design for Pet Robot Dog

NASA Astrophysics Data System (ADS)

Cheng, Chi-Tai; Yang, Yu-Ting; Miao, Shih-Heng; Wong, Ching-Chang

A pet robot dog with two ears, one mouth, one facial expression plane, and one vision system is designed and implemented so that it can do some emotional behaviors. Three processors (Inter® Pentium® M 1.0 GHz, an 8-bit processer 8051, and embedded soft-core processer NIOS) are used to control the robot. One camera, one power detector, four touch sensors, and one temperature detector are used to obtain the information of the environment. The designed robot with 20 DOF (degrees of freedom) is able to accomplish the walking motion. A behavior system is built on the implemented pet robot so that it is able to choose a suitable behavior for different environmental situation. From the practical test, we can see that the implemented pet robot dog can do some emotional interaction with the human.

SU-F-I-57: Evaluate and Optimize PET Acquisition Overlap in 18F-FDG Oncology Wholebody PET/CT: Can We Scan PET Faster?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, J; Natwa, M; Hall, NC

Purpose: The longer patient has to remain on the table during PET imaging, the higher the likelihood of motion artifacts due to patient discomfort. This study was to investigate and optimize PET acquisition overlap in 18F-FDG oncology wholebody PET/CT to speed up PET acquisition and improve patient comfort. Methods: Wholebody 18F-FDG PET/CT of phantoms, 8 pre-clinical patients (beagles) and 5 clinical oncology patients were performed in 90s/bed on a time-of-flight Gemini TF 64 system. Imaging of phantoms and beagles was acquired with reduced PET overlaps (40%, 33%, 27%, 20%, 13% and no overlap) in addition to the system default (53%).more » In human studies, 1 or 2 reduced overlaps from the listed options were used to acquire PET/CT sweeps right after the default standard of care imaging. Image quality was blindly reviewed using visual scoring criteria and quantitative SUV assessment. NEMA PET sensitivity was performed under different overlaps. Results: All PET exams demonstrated no significant impact on the visual grades for overlaps >20%. Blinded reviews assigned the best visual scores to PET using overlaps 53%–27%. Reducing overlap to 27% for oncology patients (12-bed) saved an average of ∼40% acquisition time (11min) compared to using the default overlap (18min). No significant SUV variances were found when reducing overlap to half of default for cerebellum, lung, heart, aorta, liver, fat, muscle, bone marrow, thighs and target lesions (p>0.05), except expected variability in urinary system. Conclusion: This study demonstrated by combined phantom, pre-clinical and clinical PET/CT scans that PET acquisition overlap in axial of today’s systems can be reduced and optimized. It showed that a reduction of PET acquisition overlap to 27% (half of system default) can be implemented to reduce table time by ∼40% to improve patient comfort and minimize potential motion artifacts, without prominently degrading image quality or compromising PET quantification.« less

Enhancement of dynamic myocardial perfusion PET images based on low-rank plus sparse decomposition.

PubMed

Lu, Lijun; Ma, Xiaomian; Mohy-Ud-Din, Hassan; Ma, Jianhua; Feng, Qianjin; Rahmim, Arman; Chen, Wufan

2018-02-01

The absolute quantification of dynamic myocardial perfusion (MP) PET imaging is challenged by the limited spatial resolution of individual frame images due to division of the data into shorter frames. This study aims to develop a method for restoration and enhancement of dynamic PET images. We propose that the image restoration model should be based on multiple constraints rather than a single constraint, given the fact that the image characteristic is hardly described by a single constraint alone. At the same time, it may be possible, but not optimal, to regularize the image with multiple constraints simultaneously. Fortunately, MP PET images can be decomposed into a superposition of background vs. dynamic components via low-rank plus sparse (L + S) decomposition. Thus, we propose an L + S decomposition based MP PET image restoration model and express it as a convex optimization problem. An iterative soft thresholding algorithm was developed to solve the problem. Using realistic dynamic 82 Rb MP PET scan data, we optimized and compared its performance with other restoration methods. The proposed method resulted in substantial visual as well as quantitative accuracy improvements in terms of noise versus bias performance, as demonstrated in extensive 82 Rb MP PET simulations. In particular, the myocardium defect in the MP PET images had improved visual as well as contrast versus noise tradeoff. The proposed algorithm was also applied on an 8-min clinical cardiac 82 Rb MP PET study performed on the GE Discovery PET/CT, and demonstrated improved quantitative accuracy (CNR and SNR) compared to other algorithms. The proposed method is effective for restoration and enhancement of dynamic PET images. Copyright © 2017 Elsevier B.V. All rights reserved.

Optimal Co-segmentation of Tumor in PET-CT Images with Context Information

PubMed Central

Song, Qi; Bai, Junjie; Han, Dongfeng; Bhatia, Sudershan; Sun, Wenqing; Rockey, William; Bayouth, John E.; Buatti, John M.

2014-01-01

PET-CT images have been widely used in clinical practice for radiotherapy treatment planning of the radiotherapy. Many existing segmentation approaches only work for a single imaging modality, which suffer from the low spatial resolution in PET or low contrast in CT. In this work we propose a novel method for the co-segmentation of the tumor in both PET and CT images, which makes use of advantages from each modality: the functionality information from PET and the anatomical structure information from CT. The approach formulates the segmentation problem as a minimization problem of a Markov Random Field (MRF) model, which encodes the information from both modalities. The optimization is solved using a graph-cut based method. Two sub-graphs are constructed for the segmentation of the PET and the CT images, respectively. To achieve consistent results in two modalities, an adaptive context cost is enforced by adding context arcs between the two subgraphs. An optimal solution can be obtained by solving a single maximum flow problem, which leads to simultaneous segmentation of the tumor volumes in both modalities. The proposed algorithm was validated in robust delineation of lung tumors on 23 PET-CT datasets and two head-and-neck cancer subjects. Both qualitative and quantitative results show significant improvement compared to the graph cut methods solely using PET or CT. PMID:23693127

Optimized statistical parametric mapping for partial-volume-corrected amyloid positron emission tomography in patients with Alzheimer's disease and Lewy body dementia

NASA Astrophysics Data System (ADS)

Oh, Jungsu S.; Kim, Jae Seung; Chae, Sun Young; Oh, Minyoung; Oh, Seung Jun; Cha, Seung Nam; Chang, Ho-Jong; Lee, Chong Sik; Lee, Jae Hong

2017-03-01

We present an optimized voxelwise statistical parametric mapping (SPM) of partial-volume (PV)-corrected positron emission tomography (PET) of 11C Pittsburgh Compound B (PiB), incorporating the anatomical precision of magnetic resonance image (MRI) and amyloid β (A β) burden-specificity of PiB PET. First, we applied region-based partial-volume correction (PVC), termed the geometric transfer matrix (GTM) method, to PiB PET, creating MRI-based lobar parcels filled with mean PiB uptakes. Then, we conducted a voxelwise PVC by multiplying the original PET by the ratio of a GTM-based PV-corrected PET to a 6-mm-smoothed PV-corrected PET. Finally, we conducted spatial normalizations of the PV-corrected PETs onto the study-specific template. As such, we increased the accuracy of the SPM normalization and the tissue specificity of SPM results. Moreover, lobar smoothing (instead of whole-brain smoothing) was applied to increase the signal-to-noise ratio in the image without degrading the tissue specificity. Thereby, we could optimize a voxelwise group comparison between subjects with high and normal A β burdens (from 10 patients with Alzheimer's disease, 30 patients with Lewy body dementia, and 9 normal controls). Our SPM framework outperformed than the conventional one in terms of the accuracy of the spatial normalization (85% of maximum likelihood tissue classification volume) and the tissue specificity (larger gray matter, and smaller cerebrospinal fluid volume fraction from the SPM results). Our SPM framework optimized the SPM of a PV-corrected A β PET in terms of anatomical precision, normalization accuracy, and tissue specificity, resulting in better detection and localization of A β burdens in patients with Alzheimer's disease and Lewy body dementia.

Simultaneous PET and Multispectral 3-Dimensional Fluorescence Optical Tomography Imaging System

PubMed Central

Li, Changqing; Yang, Yongfeng; Mitchell, Gregory S.; Cherry, Simon R.

2015-01-01

Integrated PET and 3-dimensional (3D) fluorescence optical tomography (FOT) imaging has unique and attractive features for in vivo molecular imaging applications. We have designed, built, and evaluated a simultaneous PET and 3D FOT system. The design of the FOT system is compatible with many existing small-animal PET scanners. Methods The 3D FOT system comprises a novel conical mirror that is used to view the whole-body surface of a mouse with an electron-multiplying charge-coupled device camera when a collimated laser beam is projected on the mouse to stimulate fluorescence. The diffusion equation was used to model the propagation of optical photons inside the mouse body, and 3D fluorescence images were reconstructed iteratively from the fluorescence intensity measurements measured from the surface of the mouse. Insertion of the conical mirror into the gantry of a small-animal PET scanner allowed simultaneous PET and 3D FOT imaging. Results The mutual interactions between PET and 3D FOT were evaluated experimentally. PET has negligible effects on 3D FOT performance. The inserted conical mirror introduces a reduction in the sensitivity and noise-equivalent count rate of the PET system and increases the scatter fraction. PET–FOT phantom experiments were performed. An in vivo experiment using both PET and FOT was also performed. Conclusion Phantom and in vivo experiments demonstrate the feasibility of simultaneous PET and 3D FOT imaging. The first in vivo simultaneous PET–FOT results are reported. PMID:21810591

HIGH-RESOLUTION L(Y)SO DETECTORS USING PMT-QUADRANT-SHARING FOR HUMAN & ANIMAL PET CAMERAS

PubMed Central

Ramirez, Rocio A.; Liu, Shitao; Liu, Jiguo; Zhang, Yuxuan; Kim, Soonseok; Baghaei, Hossain; Li, Hongdi; Wang, Yu; Wong, Wai-Hoi

2009-01-01

We developed high resolution L(Y)SO detectors for human and animal PET applications using Photomultiplier-quadrant-sharing (PQS) technology. The crystal sizes were 1.27 × 1.27 × 10 mm3 for the animal PQS-blocks and 3.25 × 3.25 × 20 mm3 for human ones. Polymer mirror film patterns (PMR) were placed between crystals as reflector. The blocks were assembled together using optical grease and wrapped by Teflon tape. The blocks were coupled to regular round PMT’s of 19/51 mm in PQS configuration. List-mode data of Ga-68 source (511 KeV) were acquired with our high yield pileup-event recovery (HYPER) electronics and data acquisition software. The high voltage bias was 1100V. Crystal decoding maps and individual crystal energy resolutions were extracted from the data. To investigate the potential imaging resolution of the PET cameras with these blocks, we used GATE (Geant4 Application for Tomographic Emission) simulation package. GATE is a GEANT4 based software toolkit for realistic simulation of PET and SPECT systems. The packing fractions of these blocks were found to be 95.6% and 98.2%. From the decoding maps, all 196 and 225 crystals were clearly identified. The average energy resolutions were 14.0% and 15.6%. For small animal PET systems, the detector ring diameter was 16.5 cm with an axial field of view (AFOV) of 11.8 cm. The simulation data suggests that a reconstructed radial (tangential) spatial resolution of 1.24 (1.25) mm near the center is potentially achievable. For the wholebody human PET systems, the detector ring diameter was 86 cm. The simulation data suggests that a reconstructed radial (tangential) spatial resolution of 3.09(3.38) mm near the center is potentially achievable. From this study we can conclude that PQS design could achieve high spatial resolutions and excellent energy resolutions on human and animal PET systems with substantially lower production costs and inexpensive readout devices. PMID:19946463

A contactless approach for respiratory gating in PET using continuous-wave radar

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ersepke, Thomas, E-mail: Thomas.Ersepke@rub.de; Büther, Florian; Heß, Mirco

Purpose: Respiratory gating is commonly used to reduce motion artifacts in positron emission tomography (PET). Clinically established methods for respiratory gating in PET require contact to the patient or a direct optical line between the sensor and the patient’s torso and time consuming preparation. In this work, a contactless method for capturing a respiratory signal during PET is presented based on continuous-wave radar. Methods: The proposed method relies on the principle of emitting an electromagnetic wave and detecting the phase shift of the reflected wave, modulated due to the respiratory movement of the patient’s torso. A 24 GHz carrier frequencymore » was chosen allowing wave propagation through plastic and clothing with high reflections at the skin surface. A detector module and signal processing algorithms were developed to extract a quantitative respiratory signal. The sensor was validated using a high precision linear table. During volunteer measurements and [{sup 18}F] FDG PET scans, the radar sensor was positioned inside the scanner bore of a PET/computed tomography scanner. As reference, pressure belt (one volunteer), depth camera-based (two volunteers, two patients), and PET data-driven (six patients) signals were acquired simultaneously and the signal correlation was quantified. Results: The developed system demonstrated a high measurement accuracy for movement detection within the submillimeter range. With the proposed method, small displacements of 25 μm could be detected, not considerably influenced by clothing or blankets. From the patient studies, the extracted respiratory radar signals revealed high correlation (Pearson correlation coefficient) to those derived from the external pressure belt and depth camera signals (r = 0.69–0.99) and moderate correlation to those of the internal data-driven signals (r = 0.53–0.70). In some cases, a cardiac signal could be visualized, due to the representation of the mechanical heart motion on the skin. Conclusions: Accurate respiratory signals were obtained successfully by the proposed method with high spatial and temporal resolution. By working without contact and passing through clothing and blankets, this approach minimizes preparation time and increases the convenience of the patient during the scan.« less

Modification of a medical PET scanner for PEPT studies

NASA Astrophysics Data System (ADS)

Sadrmomtaz, Alireza; Parker, D. J.; Byars, L. G.

2007-04-01

Over the last 20 years, positron emission tomography (PET) has developed as the most powerful functional imaging modality in medicine. Over the same period the University of Birmingham Positron Imaging Centre has applied PET to study engineering processes and developed the alternative technique of positron emission particle tracking (PEPT) in which a single radioactively labelled tracer particle is tracked by detecting simultaneously the pairs of back-to-back photons arising from positron/electron annihilation. Originally PEPT was performed using a pair of multiwire detectors, and more recently using a pair of digital gamma camera heads. In 2002 the Positron Imaging Centre acquired a medical PET scanner, an ECAT 931/08, previously used at Hammersmith Hospital. This scanner has been rebuilt in a flexible geometry for use in PEPT studies. This paper presents initial results from this system. Fast moving tracer particles can be rapidly and accurately located.

Globally optimal tumor segmentation in PET-CT images: a graph-based co-segmentation method.

PubMed

Han, Dongfeng; Bayouth, John; Song, Qi; Taurani, Aakant; Sonka, Milan; Buatti, John; Wu, Xiaodong

2011-01-01

Tumor segmentation in PET and CT images is notoriously challenging due to the low spatial resolution in PET and low contrast in CT images. In this paper, we have proposed a general framework to use both PET and CT images simultaneously for tumor segmentation. Our method utilizes the strength of each imaging modality: the superior contrast of PET and the superior spatial resolution of CT. We formulate this problem as a Markov Random Field (MRF) based segmentation of the image pair with a regularized term that penalizes the segmentation difference between PET and CT. Our method simulates the clinical practice of delineating tumor simultaneously using both PET and CT, and is able to concurrently segment tumor from both modalities, achieving globally optimal solutions in low-order polynomial time by a single maximum flow computation. The method was evaluated on clinically relevant tumor segmentation problems. The results showed that our method can effectively make use of both PET and CT image information, yielding segmentation accuracy of 0.85 in Dice similarity coefficient and the average median hausdorff distance (HD) of 6.4 mm, which is 10% (resp., 16%) improvement compared to the graph cuts method solely using the PET (resp., CT) images.

Transmission electron microscope CCD camera

DOEpatents

Downing, Kenneth H.

1999-01-01

In order to improve the performance of a CCD camera on a high voltage electron microscope, an electron decelerator is inserted between the microscope column and the CCD. This arrangement optimizes the interaction of the electron beam with the scintillator of the CCD camera while retaining optimization of the microscope optics and of the interaction of the beam with the specimen. Changing the electron beam energy between the specimen and camera allows both to be optimized.

A Sparse Representation-Based Deployment Method for Optimizing the Observation Quality of Camera Networks

PubMed Central

Wang, Chang; Qi, Fei; Shi, Guangming; Wang, Xiaotian

2013-01-01

Deployment is a critical issue affecting the quality of service of camera networks. The deployment aims at adopting the least number of cameras to cover the whole scene, which may have obstacles to occlude the line of sight, with expected observation quality. This is generally formulated as a non-convex optimization problem, which is hard to solve in polynomial time. In this paper, we propose an efficient convex solution for deployment optimizing the observation quality based on a novel anisotropic sensing model of cameras, which provides a reliable measurement of the observation quality. The deployment is formulated as the selection of a subset of nodes from a redundant initial deployment with numerous cameras, which is an ℓ0 minimization problem. Then, we relax this non-convex optimization to a convex ℓ1 minimization employing the sparse representation. Therefore, the high quality deployment is efficiently obtained via convex optimization. Simulation results confirm the effectiveness of the proposed camera deployment algorithms. PMID:23989826

Optimizing a three-stage Compton camera for measuring prompt gamma rays emitted during proton radiotherapy

PubMed Central

Peterson, S W; Robertson, D; Polf, J

2011-01-01

In this work, we investigate the use of a three-stage Compton camera to measure secondary prompt gamma rays emitted from patients treated with proton beam radiotherapy. The purpose of this study was (1) to develop an optimal three-stage Compton camera specifically designed to measure prompt gamma rays emitted from tissue and (2) to determine the feasibility of using this optimized Compton camera design to measure and image prompt gamma rays emitted during proton beam irradiation. The three-stage Compton camera was modeled in Geant4 as three high-purity germanium detector stages arranged in parallel-plane geometry. Initially, an isotropic gamma source ranging from 0 to 15 MeV was used to determine lateral width and thickness of the detector stages that provided the optimal detection efficiency. Then, the gamma source was replaced by a proton beam irradiating a tissue phantom to calculate the overall efficiency of the optimized camera for detecting emitted prompt gammas. The overall calculated efficiencies varied from ~10−6 to 10−3 prompt gammas detected per proton incident on the tissue phantom for several variations of the optimal camera design studied. Based on the overall efficiency results, we believe it feasible that a three-stage Compton camera could detect a sufficient number of prompt gammas to allow measurement and imaging of prompt gamma emission during proton radiotherapy. PMID:21048295

Hybrid radioguided occult lesion localization (hybrid ROLL) of (18)F-FDG-avid lesions using the hybrid tracer indocyanine green-(99m)Tc-nanocolloid.

PubMed

KleinJan, G H; Brouwer, O R; Mathéron, H M; Rietbergen, D D D; Valdés Olmos, R A; Wouters, M W; van den Berg, N S; van Leeuwen, F W B

2016-01-01

To assess if combined fluorescence- and radio-guided occult lesion localization (hybrid ROLL) is feasible in patients scheduled for surgical resection of non-palpable (18)F-FDG-avid lesions on PET/CT. Four patients with (18)F-FDG-avid lesions on follow-up PET/CT that were not palpable during physical examination but were suspected to harbor metastasis were enrolled. Guided by ultrasound, the hybrid tracer indocyanine green (ICG)-(99m)Tc-nanocolloid was injected centrally in the target lesion. SPECT/CT imaging was used to confirm tracer deposition. Intraoperatively, lesions were localized using a hand-held gamma ray detection probe, a portable gamma camera, and a fluorescence camera. After excision, the gamma camera was used to check the wound bed for residual activity. A total of six (18)F-FDG-avid lymph nodes were identified and scheduled for hybrid ROLL. Comparison of the PET/CT images with the acquired SPECT/CT after hybrid tracer injection confirmed accurate tracer deposition. No side effects were observed. Combined radio- and fluorescence-guidance enabled localization and excision of the target lesion in all patients. Five of the six excised lesions proved tumor-positive at histopathology. The hybrid ROLL approach appears to be feasible and can facilitate the intraoperative localization and excision of non-palpable lesions suspected to harbor tumor metastases. In addition to the initial radioguided detection, the fluorescence component of the hybrid tracer enables high-resolution intraoperative visualization of the target lesion. The procedure needs further evaluation in a larger cohort and wider range of malignancies to substantiate these preliminary findings. Copyright © 2016 Elsevier España, S.L.U. y SEMNIM. All rights reserved.

FDG-PET/CT at the end of immuno-chemotherapy in follicular lymphoma: the prognostic role of the ratio between target lesion and liver SUVmax (rPET).

PubMed

Annunziata, Salvatore; Cuccaro, Annarosa; Tisi, Maria Chiara; Hohaus, Stefan; Rufini, Vittoria

2018-06-01

To retrospectively investigate the prognostic role of the ratio between target lesion and liver SUV max (rPET) in patients with follicular lymphoma (FL) submitted to FDG-PET/CT at the end of immuno-chemotherapy (PI-PET), and to compare rPET with International Harmonization Project criteria (IHP), Deauville Score (5p-DS) and FL International Prognostic Index at diagnosis (FLIPI). Eighty-nine patients with FL undergoing PI-PET were evaluated. The receiver operating characteristic (ROC) approach was applied to identify the optimal cut-point of rPET with respect to 5-years progression free survival (PFS). The prognostic significance of rPET was compared with IHP, DS and FLIPI. Positive predictive value (PPV) and negative predictive value (NPV) were calculated using the presence of adverse events as gold standard. The ROC analysis for rPET as predictor of progression showed an optimal rPET cut-point of 0.98. Patients with positive values of IHP, DS and rPET had a PFS of 50, 30 and 31%. PPV were of 56, 80 and 80%, NPV of 83, 86 and 88%, respectively. DS and rPET differed only in two patients. FLIPI was not predictive of progression and relapse. rPET is a prognostic factor in patients with FL submitted to PI-PET. Although it has a similar prognostic power as DS, it can have methodological advantages over visual analysis. PI-PET with different evaluation systems has a stronger prognostic power than FLIPI at diagnosis, so it could be useful to identify patients with FL at risk for early relapse after immuno-chemotherapy.

Production of an 15O beam using a stable oxygen ion beam for in-beam PET imaging

NASA Astrophysics Data System (ADS)

Mohammadi, Akram; Yoshida, Eiji; Tashima, Hideaki; Nishikido, Fumihiko; Inaniwa, Taku; Kitagawa, Atsushi; Yamaya, Taiga

2017-03-01

In advanced ion therapy, the 15O ion beam is a promising candidate to treat hypoxic tumors and simultaneously monitor the delivered dose to a patient using PET imaging. This study aimed at production of an 15O beam by projectile fragmentation of a stable 16O beam in an optimal material, followed by in-beam PET imaging using a prototype OpenPET system, which was developed in the authors' group. The study was carried out in three steps: selection of the optimal target based on the highest production rate of 15O fragments; experimental production of the beam using the optimal target in the Heavy Ion Medical Accelerator Chiba (HIMAC) secondary beam course; and realization of in-beam PET imaging for the produced beam. The optimal target evaluations were done using the Monte Carlo simulation code PHITS. The fluence and mean energy of the secondary particles were simulated and the optimal target was selected based on the production rate of 15O fragments. The highest production rate of 15O was observed for a liquid hydrogen target, 3.27% for a 53 cm thick target from the 16O beam of 430 MeV/u. Since liquid hydrogen is not practically applicable in the HIMAC secondary beam course a hydrogen-rich polyethylene material, which was the second optimal target from the simulation results, was selected as the experimental target. Three polyethylene targets with thicknesses of 5, 11 or 14 cm were used to produce the 15O beam without any degrader in the beam course. The highest production rate was measured as around 0.87% for the 11 cm thick polyethylene target from the 16O beam of 430 MeV/u when the angular acceptance and momentum acceptance were set at ±13 mrad and ±2.5%, respectively. The purity of the produced beam for the three targets were around 75%, insufficient for clinical application, but it was increased to 97% by inserting a wedge shape aluminum degrader with a thickness of 1.76 cm into the beam course and that is sufficiently high. In-beam PET imaging was also performed for all produced beams using the OpenPET system. The purity improvement of the produced 15O beams was confirmed from the PET images.

Evaluation of a video-based head motion tracking system for dedicated brain PET

NASA Astrophysics Data System (ADS)

Anishchenko, S.; Beylin, D.; Stepanov, P.; Stepanov, A.; Weinberg, I. N.; Schaeffer, S.; Zavarzin, V.; Shaposhnikov, D.; Smith, M. F.

2015-03-01

Unintentional head motion during Positron Emission Tomography (PET) data acquisition can degrade PET image quality and lead to artifacts. Poor patient compliance, head tremor, and coughing are examples of movement sources. Head motion due to patient non-compliance can be an issue with the rise of amyloid brain PET in dementia patients. To preserve PET image resolution and quantitative accuracy, head motion can be tracked and corrected in the image reconstruction algorithm. While fiducial markers can be used, a contactless approach is preferable. A video-based head motion tracking system for a dedicated portable brain PET scanner was developed. Four wide-angle cameras organized in two stereo pairs are used for capturing video of the patient's head during the PET data acquisition. Facial points are automatically tracked and used to determine the six degree of freedom head pose as a function of time. The presented work evaluated the newly designed tracking system using a head phantom and a moving American College of Radiology (ACR) phantom. The mean video-tracking error was 0.99±0.90 mm relative to the magnetic tracking device used as ground truth. Qualitative evaluation with the ACR phantom shows the advantage of the motion tracking application. The developed system is able to perform tracking with accuracy close to millimeter and can help to preserve resolution of brain PET images in presence of movements.

Optimization of brain PET imaging for a multicentre trial: the French CATI experience.

PubMed

Habert, Marie-Odile; Marie, Sullivan; Bertin, Hugo; Reynal, Moana; Martini, Jean-Baptiste; Diallo, Mamadou; Kas, Aurélie; Trébossen, Régine

2016-12-01

CATI is a French initiative launched in 2010 to handle the neuroimaging of a large cohort of subjects recruited for an Alzheimer's research program called MEMENTO. This paper presents our test protocol and results obtained for the 22 PET centres (overall 13 different scanners) involved in the MEMENTO cohort. We determined acquisition parameters using phantom experiments prior to patient studies, with the aim of optimizing PET quantitative values to the highest possible per site, while reducing, if possible, variability across centres. Jaszczak's and 3D-Hoffman's phantom measurements were used to assess image spatial resolution (ISR), recovery coefficients (RC) in hot and cold spheres, and signal-to-noise ratio (SNR). For each centre, the optimal reconstruction parameters were chosen as those maximizing ISR and RC without a noticeable decrease in SNR. Point-spread-function (PSF) modelling reconstructions were discarded. The three figures of merit extracted from the images reconstructed with optimized parameters and routine schemes were compared, as were volumes of interest ratios extracted from Hoffman acquisitions. The net effect of the 3D-OSEM reconstruction parameter optimization was investigated on a subset of 18 scanners without PSF modelling reconstruction. Compared to the routine parameters of the 22 PET centres, average RC in the two smallest hot and cold spheres and average ISR remained stable or were improved with the optimized reconstruction, at the expense of slight SNR degradation, while the dispersion of values was reduced. For the subset of scanners without PSF modelling, the mean RC of the smallest hot sphere obtained with the optimized reconstruction was significantly higher than with routine reconstruction. The putamen and caudate-to-white matter ratios measured on 3D-Hoffman acquisitions of all centres were also significantly improved by the optimization, while the variance was reduced. This study provides guidelines for optimizing quantitative results for multicentric PET neuroimaging trials.

Plasma-mediated grafting of poly(ethylene glycol) on polyamide and polyester surfaces and evaluation of antifouling ability of modified substrates.

PubMed

Dong, Baiyan; Jiang, Hongquan; Manolache, Sorin; Wong, Amy C Lee; Denes, Ferencz S

2007-06-19

A simple cold plasma technique was developed to functionalize the surfaces of polyamide (PA) and polyester (PET) for the grafting of polyethylene glycol (PEG) with the aim of reducing biofilm formation. The surfaces of PA and PET were treated with silicon tetrachloride (SiCl4) plasma, and PEG was grafted onto plasma-functionalized substrates (PA-PEG, PET-PEG). Different molecular weights of PEG and grafting times were tested to obtain optimal surface coverage by PEG as monitored by electron spectroscopy for chemical analysis (ESCA). The presence of a predominant C-O peak on the PEG-modified substrates indicated that the grafting was successful. Data from hydroxyl group derivatization and water contact angle measurement also indicated the presence of PEG after grafting. The PEG-grafted PA and PET under optimal conditions had similar chemical composition and hydrophilicity; however, different morphology changes were observed after grafting. Both PA-PEG and PET-PEG surfaces developed under optimal plasma conditions showed about 96% reduction in biofilm formation by Listeria monocytogenes compared with that of the corresponding unmodified substrates. This plasma functionalization method provided an efficient way to graft PEG onto PA and PET surfaces. Because of the high reactivity of Si-Cl species, this method could potentially be applied to other polymeric materials.

Optimization of the protocols for the use of contrast agents in PET/CT studies.

PubMed

Pelegrí Martínez, L; Kohan, A A; Vercher Conejero, J L

The introduction of PET/CT scanners in clinical practice in 1998 has improved care for oncologic patients throughout the clinical pathway, from the initial diagnosis of disease through the evaluation of the response to treatment to screening for possible recurrence. The CT component of a PET/CT study is used to correct the attenuation of PET studies; CT also provides anatomic information about the distribution of the radiotracer. CT is especially useful in situations where PET alone can lead to false positives and false negatives, and CT thereby improves the diagnostic performance of PET. The use of intravenous or oral contrast agents and optimal CT protocols have improved the detection and characterization of lesions. However, there are circumstances in which the systematic use of contrast agents is not justified. The standard acquisition in PET/CT scanners is the whole body protocol, but this can lead to artifacts due to the position of patients and respiratory movements between the CT and PET acquisitions. This article discusses these aspects from a constructive perspective with the aim of maximizing the diagnostic potential of PET/CT and providing better care for patients. Copyright © 2016 SERAM. Publicado por Elsevier España, S.L.U. All rights reserved.

Performance modeling of a wearable brain PET (BET) camera

NASA Astrophysics Data System (ADS)

Schmidtlein, C. R.; Turner, J. N.; Thompson, M. O.; Mandal, K. C.; Häggström, I.; Zhang, J.; Humm, J. L.; Feiglin, D. H.; Krol, A.

2016-03-01

Purpose: To explore, by means of analytical and Monte Carlo modeling, performance of a novel lightweight and low-cost wearable helmet-shaped Brain PET (BET) camera based on thin-film digital Geiger Avalanche Photo Diode (dGAPD) with LSO and LaBr3 scintillators for imaging in vivo human brain processes for freely moving and acting subjects responding to various stimuli in any environment. Methods: We performed analytical and Monte Carlo modeling PET performance of a spherical cap BET device and cylindrical brain PET (CYL) device, both with 25 cm diameter and the same total mass of LSO scintillator. Total mass of LSO in both the BET and CYL systems is about 32 kg for a 25 mm thick scintillator, and 13 kg for 10 mm thick scintillator (assuming an LSO density of 7.3 g/ml). We also investigated a similar system using an LaBr3 scintillator corresponding to 22 kg and 9 kg for the 25 mm and 10 mm thick systems (assuming an LaBr3 density of 5.08 g/ml). In addition, we considered a clinical whole body (WB) LSO PET/CT scanner with 82 cm ring diameter and 15.8 cm axial length to represent a reference system. BET consisted of distributed Autonomous Detector Arrays (ADAs) integrated into Intelligent Autonomous Detector Blocks (IADBs). The ADA comprised of an array of small LYSO scintillator volumes (voxels with base a×a: 1.0 <= a <= 2.0 mm and length c: 3.0 <= c <= 6.0 mm) with 5-65 μm thick reflective layers on its five sides and sixth side optically coupled to the matching array of dGAPDs and processing electronics with total thickness of 50 μm. Simulated energy resolution was 10.8% and 3.3% for LSO and LaBr3 respectively and the coincidence window was set at 2 ns. The brain was simulated as a sphere of uniform F-18 activity with diameter of 10 cm embedded in a center of water sphere with diameter of 10 cm. Results: Analytical and Monte Carlo models showed similar results for lower energy window values (458 keV versus 445 keV for LSO, and 492 keV versus 485 keV for LaBr3), and for the relative performance of system sensitivity. Monte Carlo results further showed that the BET geometry had >50% better noise equivalent count (NEC) performance relative to the CYL geometry, and >1100% better performance than a WB geometry for 25 mm thick LSO and LaBr3. For 10 mm thick LaBr3 equivalent mass systems LSO (7 mm thick) performed ~40% higher NEC than LaBr3. Analytic and Monte Carlo simulations also showed that 1×1×3 mm scintillator crystals can achieve ~1.2 mm FWHM spatial resolution. Conclusions: This study shows that a spherical cap brain PET system can provide improved NEC while preserving spatial resolution when compared to an equivalent dedicated cylindrical PET brain camera and shows greatly improved PET performance relative to a conventional whole body PET/CT. In addition, our simulations show that LSO will generally outperform LaBr3 for NEC unless the timing resolution for LaBr3 is considerably smaller than presently used for LSO, i.e. well below 300 ps.

Multi-focused microlens array optimization and light field imaging study based on Monte Carlo method.

PubMed

Li, Tian-Jiao; Li, Sai; Yuan, Yuan; Liu, Yu-Dong; Xu, Chuan-Long; Shuai, Yong; Tan, He-Ping

2017-04-03

Plenoptic cameras are used for capturing flames in studies of high-temperature phenomena. However, simulations of plenoptic camera models can be used prior to the experiment improve experimental efficiency and reduce cost. In this work, microlens arrays, which are based on the established light field camera model, are optimized into a hexagonal structure with three types of microlenses. With this improved plenoptic camera model, light field imaging of static objects and flame are simulated using the calibrated parameters of the Raytrix camera (R29). The optimized models improve the image resolution, imaging screen utilization, and shooting range of depth of field.

Intercampus network of the Department of Radiology, School of Medicine, Indiana University

NASA Astrophysics Data System (ADS)

Witt, Robert M.; Gibbs, Thomas; Holden, Robert W.

1994-05-01

During the past year, the Department of Radiology, School of Medicine, Indiana University designed, specified, and installed a campus wide network. The network supports three functions: a laser camera network to allow the transfer of hard copy images across the campus; a positron emission tomography (PET) network to allow the interconnection of the workstations comprising the PET system; and a future personal computer network to allow support of departmental administrative functions with an upgrade path to allow the display of soft copy images in physician offices and other locations in the department.

Development and Optimization of an Injury Prevention Intervention for Physical Education Teachers

ERIC Educational Resources Information Center

Vercruysse, Sien; De Clercq, Dirk; Goossens, Lennert; Aelterman, Nathalie; Haerens, Leen

2017-01-01

Background: Injury prevention is highly needed in physically active populations, such as pre-service and in-service physical education teachers (PETs). As a lack of adherence to preventive strategies is problematic in injury, it seems crucial to develop and optimize interventions that correspond to the specific needs and wishes of PETs. Aim: The…

NEMA NU 4-2008 validation and applications of the PET-SORTEO Monte Carlo simulations platform for the geometry of the Inveon PET preclinical scanner

NASA Astrophysics Data System (ADS)

Boisson, F.; Wimberley, C. J.; Lehnert, W.; Zahra, D.; Pham, T.; Perkins, G.; Hamze, H.; Gregoire, M.-C.; Reilhac, A.

2013-10-01

Monte Carlo-based simulation of positron emission tomography (PET) data plays a key role in the design and optimization of data correction and processing methods. Our first aim was to adapt and configure the PET-SORTEO Monte Carlo simulation program for the geometry of the widely distributed Inveon PET preclinical scanner manufactured by Siemens Preclinical Solutions. The validation was carried out against actual measurements performed on the Inveon PET scanner at the Australian Nuclear Science and Technology Organisation in Australia and at the Brain & Mind Research Institute and by strictly following the NEMA NU 4-2008 standard. The comparison of simulated and experimental performance measurements included spatial resolution, sensitivity, scatter fraction and count rates, image quality and Derenzo phantom studies. Results showed that PET-SORTEO reliably reproduces the performances of this Inveon preclinical system. In addition, imaging studies showed that the PET-SORTEO simulation program provides raw data for the Inveon scanner that can be fully corrected and reconstructed using the same programs as for the actual data. All correction techniques (attenuation, scatter, randoms, dead-time, and normalization) can be applied on the simulated data leading to fully quantitative reconstructed images. In the second part of the study, we demonstrated its ability to generate fast and realistic biological studies. PET-SORTEO is a workable and reliable tool that can be used, in a classical way, to validate and/or optimize a single PET data processing step such as a reconstruction method. However, we demonstrated that by combining a realistic simulated biological study ([11C]Raclopride here) involving different condition groups, simulation allows one also to assess and optimize the data correction, reconstruction and data processing line flow as a whole, specifically for each biological study, which is our ultimate intent.

3D-segmentation of the 18F-choline PET signal for target volume definition in radiation therapy of the prostate.

PubMed

Ciernik, I Frank; Brown, Derek W; Schmid, Daniel; Hany, Thomas; Egli, Peter; Davis, J Bernard

2007-02-01

Volumetric assessment of PET signals becomes increasingly relevant for radiotherapy (RT) planning. Here, we investigate the utility of 18F-choline PET signals to serve as a structure for semi-automatic segmentation for forward treatment planning of prostate cancer. 18F-choline PET and CT scans of ten patients with histologically proven prostate cancer without extracapsular growth were acquired using a combined PET/CT scanner. Target volumes were manually delineated on CT images using standard software. Volumes were also obtained from 18F-choline PET images using an asymmetrical segmentation algorithm. PTVs were derived from CT 18F-choline PET based clinical target volumes (CTVs) by automatic expansion and comparative planning was performed. As a read-out for dose given to non-target structures, dose to the rectal wall was assessed. Planning target volumes (PTVs) derived from CT and 18F-choline PET yielded comparable results. Optimal matching of CT and 18F-choline PET derived volumes in the lateral and cranial-caudal directions was obtained using a background-subtracted signal thresholds of 23.0+/-2.6%. In antero-posterior direction, where adaptation compensating for rectal signal overflow was required, optimal matching was achieved with a threshold of 49.5+/-4.6%. 3D-conformal planning with CT or 18F-choline PET resulted in comparable doses to the rectal wall. Choline PET signals of the prostate provide adequate spatial information amendable to standardized asymmetrical region growing algorithms for PET-based target volume definition for external beam RT.

The effect of 18F-FDG-PET image reconstruction algorithms on the expression of characteristic metabolic brain network in Parkinson's disease.

PubMed

Tomše, Petra; Jensterle, Luka; Rep, Sebastijan; Grmek, Marko; Zaletel, Katja; Eidelberg, David; Dhawan, Vijay; Ma, Yilong; Trošt, Maja

2017-09-01

To evaluate the reproducibility of the expression of Parkinson's Disease Related Pattern (PDRP) across multiple sets of 18F-FDG-PET brain images reconstructed with different reconstruction algorithms. 18F-FDG-PET brain imaging was performed in two independent cohorts of Parkinson's disease (PD) patients and normal controls (NC). Slovenian cohort (20 PD patients, 20 NC) was scanned with Siemens Biograph mCT camera and reconstructed using FBP, FBP+TOF, OSEM, OSEM+TOF, OSEM+PSF and OSEM+PSF+TOF. American Cohort (20 PD patients, 7 NC) was scanned with GE Advance camera and reconstructed using 3DRP, FORE-FBP and FORE-Iterative. Expressions of two previously-validated PDRP patterns (PDRP-Slovenia and PDRP-USA) were calculated. We compared the ability of PDRP to discriminate PD patients from NC, differences and correlation between the corresponding subject scores and ROC analysis results across the different reconstruction algorithms. The expression of PDRP-Slovenia and PDRP-USA networks was significantly elevated in PD patients compared to NC (p<0.0001), regardless of reconstruction algorithms. PDRP expression strongly correlated between all studied algorithms and the reference algorithm (r⩾0.993, p<0.0001). Average differences in the PDRP expression among different algorithms varied within 0.73 and 0.08 of the reference value for PDRP-Slovenia and PDRP-USA, respectively. ROC analysis confirmed high similarity in sensitivity, specificity and AUC among all studied reconstruction algorithms. These results show that the expression of PDRP is reproducible across a variety of reconstruction algorithms of 18F-FDG-PET brain images. PDRP is capable of providing a robust metabolic biomarker of PD for multicenter 18F-FDG-PET images acquired in the context of differential diagnosis or clinical trials. Copyright © 2017 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

Silicon detectors for combined MR-PET and MR-SPECT imaging

NASA Astrophysics Data System (ADS)

Studen, A.; Brzezinski, K.; Chesi, E.; Cindro, V.; Clinthorne, N. H.; Cochran, E.; Grošičar, B.; Grkovski, M.; Honscheid, K.; Kagan, H.; Lacasta, C.; Llosa, G.; Mikuž, M.; Stankova, V.; Weilhammer, P.; Žontar, D.

2013-02-01

Silicon based devices can extend PET-MR and SPECT-MR imaging to applications, where their advantages in performance outweigh benefits of high statistical counts. Silicon is in many ways an excellent detector material with numerous advantages, among others: excellent energy and spatial resolution, mature processing technology, large signal to noise ratio, relatively low price, availability, versatility and malleability. The signal in silicon is also immune to effects of magnetic field at the level normally used in MR devices. Tests in fields up to 7 T were performed in a study to determine effects of magnetic field on positron range in a silicon PET device. The curvature of positron tracks in direction perpendicular to the field's orientation shortens the distance between emission and annihilation point of the positron. The effect can be fully appreciated for a rotation of the sample for a fixed field direction, compressing range in all dimensions. A popular Ga-68 source was used showing a factor of 2 improvement in image noise compared to zero field operation. There was also a little increase in noise as the reconstructed resolution varied between 2.5 and 1.5 mm. A speculative applications can be recognized in both emission modalities, SPECT and PET. Compton camera is a subspecies of SPECT, where a silicon based scatter as a MR compatible part could inserted into the MR bore and the secondary detector could operate in less constrained environment away from the magnet. Introducing a Compton camera also relaxes requirements of the radiotracers used, extending the range of conceivable photon energies beyond 140.5 keV of the Tc-99m. In PET, one could exploit the compressed sub-millimeter range of positrons in the magnetic field. To exploit the advantage, detectors with spatial resolution commensurate to the effect must be used with silicon being an excellent candidate. Measurements performed outside of the MR achieving spatial resolution below 1 mm are reported.

Optimal erasure protection for scalably compressed video streams with limited retransmission.

PubMed

Taubman, David; Thie, Johnson

2005-08-01

This paper shows how the priority encoding transmission (PET) framework may be leveraged to exploit both unequal error protection and limited retransmission for RD-optimized delivery of streaming media. Previous work on scalable media protection with PET has largely ignored the possibility of retransmission. Conversely, the PET framework has not been harnessed by the substantial body of previous work on RD optimized hybrid forward error correction/automatic repeat request schemes. We limit our attention to sources which can be modeled as independently compressed frames (e.g., video frames), where each element in the scalable representation of each frame can be transmitted in one or both of two transmission slots. An optimization algorithm determines the level of protection which should be assigned to each element in each slot, subject to transmission bandwidth constraints. To balance the protection assigned to elements which are being transmitted for the first time with those which are being retransmitted, the proposed algorithm formulates a collection of hypotheses concerning its own behavior in future transmission slots. We show how the PET framework allows for a decoupled optimization algorithm with only modest complexity. Experimental results obtained with Motion JPEG2000 compressed video demonstrate that substantial performance benefits can be obtained using the proposed framework.

Performance Evaluation of a Dedicated Preclinical PET/CT System for the Assessment of Mineralization Process in a Mouse Model of Atherosclerosis.

PubMed

Rucher, Guillaume; Cameliere, Lucie; Fendri, Jihene; Abbas, Ahmed; Dupont, Kevin; Kamel, Said; Delcroix, Nicolas; Dupont, Axel; Berger, Ludovic; Manrique, Alain

2018-04-30

The purpose of this study was to assess the impact of positron emission tomography/X-ray computed tomography (PET/CT) acquisition and reconstruction parameters on the assessment of mineralization process in a mouse model of atherosclerosis. All experiments were performed on a dedicated preclinical PET/CT system. CT was evaluated using five acquisition configurations using both a tungsten wire phantom for in-plane resolution assessment and a bar pattern phantom for cross-plane resolution. Furthermore, the radiation dose of these acquisition configurations was calculated. The PET system was assessed using longitudinal line sources to determine the optimal reconstruction parameters by measuring central resolution and its coefficient of variation. An in vivo PET study was performed using uremic ApoE -/- , non-uremic ApoE -/- , and control mice to evaluate optimal PET reconstruction parameters for the detection of sodium [ 18 F]fluoride (Na[ 18 F]F) aortic uptake and for quantitative measurement of Na[ 18 F]F bone influx (Ki) with a Patlak analysis. For CT, the use of 1 × 1 and 2 × 2 binning detector mode increased both in-plane and cross-plane resolution. However, resolution improvement (163 to 62 μm for in-plane resolution) was associated with an important radiation dose increase (1.67 to 32.78 Gy). With PET, 3D-ordered subset expectation maximization (3D-OSEM) algorithm increased the central resolution compared to filtered back projection (1.42 ± 0.35 mm vs. 1.91 ± 0.08, p < 0.001). The use of 3D-OSEM with eight iterations and a zoom factor 2 yielded optimal PET resolution for preclinical study (FWHM = 0.98 mm). These PET reconstruction parameters allowed the detection of Na[ 18 F]F aortic uptake in 3/14 ApoE -/- mice and demonstrated a decreased Ki in uremic ApoE -/- compared to non-uremic ApoE -/- and control mice (p < 0.006). Optimizing reconstruction parameters significantly impacted on the assessment of mineralization process in a preclinical model of accelerated atherosclerosis using Na[ 18 F]F PET. In addition, improving the CT resolution was associated with a dramatic radiation dose increase.

A modular positron camera for the study of industrial processes

NASA Astrophysics Data System (ADS)

Leadbeater, T. W.; Parker, D. J.

2011-10-01

Positron imaging techniques rely on the detection of the back-to-back annihilation photons arising from positron decay within the system under study. A standard technique, called positron emitting particle tracking (PEPT) [1], uses a number of these detected events to rapidly determine the position of a positron emitting tracer particle introduced into the system under study. Typical applications of PEPT are in the study of granular and multi-phase materials in the disciplines of engineering and the physical sciences. Using components from redundant medical PET scanners a modular positron camera has been developed. This camera consists of a number of small independent detector modules, which can be arranged in custom geometries tailored towards the application in question. The flexibility of the modular camera geometry allows for high photon detection efficiency within specific regions of interest, the ability to study large and bulky systems and the application of PEPT to difficult or remote processes as the camera is inherently transportable.

Optimal monochromatic color combinations for fusion imaging of FDG-PET and diffusion-weighted MR images.

PubMed

Kamei, Ryotaro; Watanabe, Yuji; Sagiyama, Koji; Isoda, Takuro; Togao, Osamu; Honda, Hiroshi

2018-05-23

To investigate the optimal monochromatic color combination for fusion imaging of FDG-PET and diffusion-weighted MR images (DW) regarding lesion conspicuity of each image. Six linear monochromatic color-maps of red, blue, green, cyan, magenta, and yellow were assigned to each of the FDG-PET and DW images. Total perceptual color differences of the lesions were calculated based on the lightness and chromaticity measured with the photometer. Visual lesion conspicuity was also compared among the PET-only, DW-only and PET-DW-double positive portions with mean conspicuity scores. Statistical analysis was performed with a one-way analysis of variance and Spearman's rank correlation coefficient. Among all the 12 possible monochromatic color-map combinations, the 3 combinations of red/cyan, magenta/green, and red/green produced the highest conspicuity scores. Total color differences between PET-positive and double-positive portions correlated with conspicuity scores (ρ = 0.2933, p < 0.005). Lightness differences showed a significant negative correlation with conspicuity scores between the PET-only and DWI-only positive portions. Chromaticity differences showed a marginally significant correlation with conspicuity scores between DWI-positive and double-positive portions. Monochromatic color combinations can facilitate the visual evaluation of FDG-uptake and diffusivity as well as registration accuracy on the FDG-PET/DW fusion images, when red- and green-colored elements are assigned to FDG-PET and DW images, respectively.

Optimization of the spatial resolution for the GE discovery PET/CT 710 by using NEMA NU 2-2007 standards

NASA Astrophysics Data System (ADS)

Yoon, Hyun Jin; Jeong, Young Jin; Son, Hye Joo; Kang, Do-Young; Hyun, Kyung-Yae; Lee, Min-Kyung

2015-01-01

The spatial resolution in positron emission tomography (PET) is fundamentally limited by the geometry of the detector element, the positron's recombination range with electrons, the acollinearity of the positron, the crystal decoding error, the penetration into the detector ring, and the reconstruction algorithms. In this paper, optimized parameters are suggested to produce high-resolution PET images by using an iterative reconstruction algorithm. A phantom with three point sources structured with three capillary tubes was prepared with an axial extension of less than 1 mm and was filled with 18F-fluorodeoxyglucose (18F-FDG) with concentrations above 200 MBq/cc. The performance measures of all the PET images were acquired according to the National Electrical Manufacturers Association (NEMA) NU 2-2007 standards procedures. The parameters for the iterative reconstruction were adjusted around the values recommended by General Electric GE, and the optimized values of the spatial resolution and the full width at half maximum (FWHM) or the full width at tenth of maximum (FWTM) values were found for the best PET resolution. The axial and the transverse spatial resolutions, according to the filtered back-projection (FBP) at 1 cm off-axis, were 4.81 and 4.48 mm, respectively. The axial and the transaxial spatial resolutions at 10 cm off-axis were 5.63 mm and 5.08 mm, respectively, and the trans-axial resolution at 10 cm was evaluated as the average of the radial and the tangential measurements. The recommended optimized parameters of the spatial resolution according to the NEMA phantom for the number of subsets, the number of iterations, and the Gaussian post-filter are 12, 3, and 3 mm for the iterative reconstruction VUE Point HD without the SharpIR algorithm (HD), and 12, 12, and 5.2 mm with SharpIR (HD.S), respectively, according to the Advantage Workstation Volume Share 5 (AW4.6). The performance measurements for the GE Discovery PET/CT 710 using the NEMA NU 2-2007 standards from our results will be helpful in the quantitative analysis of PET scanner images. The spatial resolution was modified more by using an improved algorithm such as HD.S, than by using HD and FBP. The use of the optimized parameters for iterative reconstructions is strongly recommended for qualitative images from the GE Discovery PET/CT 710 scanner.

Towards tracer dose reduction in PET studies: Simulation of dose reduction by retrospective randomized undersampling of list-mode data.

PubMed

Gatidis, Sergios; Würslin, Christian; Seith, Ferdinand; Schäfer, Jürgen F; la Fougère, Christian; Nikolaou, Konstantin; Schwenzer, Nina F; Schmidt, Holger

2016-01-01

Optimization of tracer dose regimes in positron emission tomography (PET) imaging is a trade-off between diagnostic image quality and radiation exposure. The challenge lies in defining minimal tracer doses that still result in sufficient diagnostic image quality. In order to find such minimal doses, it would be useful to simulate tracer dose reduction as this would enable to study the effects of tracer dose reduction on image quality in single patients without repeated injections of different amounts of tracer. The aim of our study was to introduce and validate a method for simulation of low-dose PET images enabling direct comparison of different tracer doses in single patients and under constant influencing factors. (18)F-fluoride PET data were acquired on a combined PET/magnetic resonance imaging (MRI) scanner. PET data were stored together with the temporal information of the occurrence of single events (list-mode format). A predefined proportion of PET events were then randomly deleted resulting in undersampled PET data. These data sets were subsequently reconstructed resulting in simulated low-dose PET images (retrospective undersampling of list-mode data). This approach was validated in phantom experiments by visual inspection and by comparison of PET quality metrics contrast recovery coefficient (CRC), background-variability (BV) and signal-to-noise ratio (SNR) of measured and simulated PET images for different activity concentrations. In addition, reduced-dose PET images of a clinical (18)F-FDG PET dataset were simulated using the proposed approach. (18)F-PET image quality degraded with decreasing activity concentrations with comparable visual image characteristics in measured and in corresponding simulated PET images. This result was confirmed by quantification of image quality metrics. CRC, SNR and BV showed concordant behavior with decreasing activity concentrations for measured and for corresponding simulated PET images. Simulation of dose-reduced datasets based on clinical (18)F-FDG PET data demonstrated the clinical applicability of the proposed data. Simulation of PET tracer dose reduction is possible with retrospective undersampling of list-mode data. Resulting simulated low-dose images have equivalent characteristics with PET images actually measured at lower doses and can be used to derive optimal tracer dose regimes.

Are Pets in the Bedroom a Problem?

PubMed

Krahn, Lois E; Tovar, M Diane; Miller, Bernie

2015-12-01

The presence of pets in the bedroom can alter the sleep environment in ways that could affect sleep. Data were collected by questionnaire and interview from 150 consecutive patients seen at the Center for Sleep Medicine, Mayo Clinic in Arizona. Seventy-four people (49%) reported having pets, with 31 (41% of pet owners) having multiple pets. More than half of pet owners (56%) allowed their pets to sleep in the bedroom. Fifteen pet owners (20%) described their pets as disruptive, whereas 31 (41%) perceived their pets as unobtrusive or even beneficial to sleep. Health care professionals working with patients with sleep concerns should inquire about the presence of companion animals in the sleep environment to help them find solutions and optimize their sleep. Copyright © 2015 Mayo Foundation for Medical Education and Research. Published by Elsevier Inc. All rights reserved.

Flow optimization study of a batch microfluidics PET tracer synthesizing device

PubMed Central

Elizarov, Arkadij M.; Meinhart, Carl; van Dam, R. Michael; Huang, Jiang; Daridon, Antoine; Heath, James R.; Kolb, Hartmuth C.

2010-01-01

We present numerical modeling and experimental studies of flow optimization inside a batch microfluidic micro-reactor used for synthesis of human-scale doses of Positron Emission Tomography (PET) tracers. Novel techniques are used for mixing within, and eluting liquid out of, the coin-shaped reaction chamber. Numerical solutions of the general incompressible Navier Stokes equations along with time-dependent elution scalar field equation for the three dimensional coin-shaped geometry were obtained and validated using fluorescence imaging analysis techniques. Utilizing the approach presented in this work, we were able to identify optimized geometrical and operational conditions for the micro-reactor in the absence of radioactive material commonly used in PET related tracer production platforms as well as evaluate the designed and fabricated micro-reactor using numerical and experimental validations. PMID:21072595

Optimal gross tumor volume definition in lung-sparing intensity modulated radiotherapy for pleural mesothelioma: an in silico study.

PubMed

Botticella, Angela; Defraene, Gilles; Nackaerts, Kristiaan; Deroose, Christophe M; Coolen, Johan; Nafteux, Philippe; Peeters, Stephanie; Ricardi, Umberto; De Ruysscher, Dirk

2016-12-01

The gross tumor volume (GTV) definition for malignant pleural mesothelioma (MPM) is ill-defined. We therefore investigated which imaging modality is optimal: computed tomography (CT) with intravenous contrast (IVC), positron emission tomography-CT (PET/CT) or magnetic resonance imaging (MRI). Sixteen consecutive patients with untreated stage I-IV MPM were included. Patients with prior pleurodesis were excluded. CT with IVC, 18FDG-PET/CT and MRI (T2 and contrast-enhanced T1) were obtained. CT was rigidly co-registered with PET/CT and with MRI. Three sets of pleural GTVs were defined: GTV CT , GTV CT+PET/CT and GTV CT+MRI . Quantitative and qualitative evaluations of the contoured GTVs were performed. Compared to CT-based GTV definition, PET/CT identified additional tumor sites (defined as either separate nodules or greater extent of a known tumor) in 12/16 patients. Compared to either CT or PET/CT, MRI identified additional tumor sites in 15/16 patients (p = .7). The mean GTV CT , GTV CT+PET/CT and GTV CT+MRI [±standard deviation (SD)] were 630.1 cm 3 (±302.81), 640.23 cm 3 (±302.83) and 660.8 cm 3 (±290.8), respectively. Differences in mean volumes were not significant. The mean Jaccard Index was significantly lower in MRI-based contours versus all the others. As MRI identified additional pleural disease sites in the majority of patients, it may play a role in optimal target volume definition.

Low-dose computed tomography scans with automatic exposure control for patients of different ages undergoing cardiac PET/CT and SPECT/CT.

PubMed

Yang, Ching-Ching; Yang, Bang-Hung; Tu, Chun-Yuan; Wu, Tung-Hsin; Liu, Shu-Hsin

2017-06-01

This study aimed to evaluate the efficacy of automatic exposure control (AEC) in order to optimize low-dose computed tomography (CT) protocols for patients of different ages undergoing cardiac PET/CT and single-photon emission computed tomography/computed tomography (SPECT/CT). One PET/CT and one SPECT/CT were used to acquire CT images for four anthropomorphic phantoms representative of 1-year-old, 5-year-old and 10-year-old children and an adult. For the hybrid systems investigated in this study, the radiation dose and image quality of cardiac CT scans performed with AEC activated depend mainly on the selection of a predefined image quality index. Multiple linear regression methods were used to analyse image data from anthropomorphic phantom studies to investigate the effects of body size and predefined image quality index on CT radiation dose in cardiac PET/CT and SPECT/CT scans. The regression relationships have a coefficient of determination larger than 0.9, indicating a good fit to the data. According to the regression models, low-dose protocols using the AEC technique were optimized for patients of different ages. In comparison with the standard protocol with AEC activated for adult cardiac examinations used in our clinical routine practice, the optimized paediatric protocols in PET/CT allow 32.2, 63.7 and 79.2% CT dose reductions for anthropomorphic phantoms simulating 10-year-old, 5-year-old and 1-year-old children, respectively. The corresponding results for cardiac SPECT/CT are 8.4, 51.5 and 72.7%. AEC is a practical way to reduce CT radiation dose in cardiac PET/CT and SPECT/CT, but the AEC settings should be determined properly for optimal effect. Our results show that AEC does not eliminate the need for paediatric protocols and CT examinations using the AEC technique should be optimized for paediatric patients to reduce the radiation dose as low as reasonably achievable.

Robust Video Stabilization Using Particle Keypoint Update and l1-Optimized Camera Path

PubMed Central

Jeon, Semi; Yoon, Inhye; Jang, Jinbeum; Yang, Seungji; Kim, Jisung; Paik, Joonki

2017-01-01

Acquisition of stabilized video is an important issue for various type of digital cameras. This paper presents an adaptive camera path estimation method using robust feature detection to remove shaky artifacts in a video. The proposed algorithm consists of three steps: (i) robust feature detection using particle keypoints between adjacent frames; (ii) camera path estimation and smoothing; and (iii) rendering to reconstruct a stabilized video. As a result, the proposed algorithm can estimate the optimal homography by redefining important feature points in the flat region using particle keypoints. In addition, stabilized frames with less holes can be generated from the optimal, adaptive camera path that minimizes a temporal total variation (TV). The proposed video stabilization method is suitable for enhancing the visual quality for various portable cameras and can be applied to robot vision, driving assistant systems, and visual surveillance systems. PMID:28208622

Smart point-of-care systems for molecular diagnostics based on nanotechnology: whole blood glucose analysis

NASA Astrophysics Data System (ADS)

Devadhasan, Jasmine P.; Kim, Sanghyo

2015-07-01

Complementary metal oxide semiconductor (CMOS) image sensors are received great attention for their high efficiency in biological applications. The present work describes a CMOS image sensor-based whole blood glucose monitoring system through a point-of-care (POC) approach. A simple poly-ethylene terephthalate (PET) film chip was developed to carry out the enzyme kinetic reaction at various concentrations of blood glucose. In this technique, assay reagent was adsorbed onto amine functionalized silica (AFSiO2) nanoparticles in order to achieve glucose oxidation on the PET film chip. The AFSiO2 nanoparticles can immobilize the assay reagent with an electrostatic attraction and eased to develop the opaque platform which was technically suitable chip to analyze by the camera module. The oxidized glucose then produces a green color according to the glucose concentration and is analyzed by the camera module as a photon detection technique. The photon number decreases with increasing glucose concentration. The simple sensing approach, utilizing enzyme immobilized AFSiO2 nanoparticle chip and assay detection method was developed for quantitative glucose measurement.

MO-FG-207-03: Maximizing the Utility of Integrated PET/MRI in Clinical Applications

DOE Office of Scientific and Technical Information (OSTI.GOV)

Behr, S.

2015-06-15

The use of integrated PET/MRI systems in clinical applications can best benefit from understanding their technological advances and limitations. The currently available clinical PET/MRI systems have their own characteristics. Thorough analyses of existing technical data and evaluation of necessary performance metrics for quality assurances could be conducted to optimize application-specific PET/MRI protocols. This Symposium will focus on technical advances and limitations of clinical PET/MRI systems, and how this exciting imaging modality can be utilized in applications that can benefit from both PET and MRI. Learning Objectives: To understand the technological advances of clinical PET/MRI systems To correctly identify clinical applicationsmore » that can benefit from PET/MRI To understand ongoing work to further improve the current PET/MRI technology Floris Jansen is a GE Healthcare employee.« less

MO-FG-207-00: Technological Advances in PET/MR Imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

2015-06-15

The use of integrated PET/MRI systems in clinical applications can best benefit from understanding their technological advances and limitations. The currently available clinical PET/MRI systems have their own characteristics. Thorough analyses of existing technical data and evaluation of necessary performance metrics for quality assurances could be conducted to optimize application-specific PET/MRI protocols. This Symposium will focus on technical advances and limitations of clinical PET/MRI systems, and how this exciting imaging modality can be utilized in applications that can benefit from both PET and MRI. Learning Objectives: To understand the technological advances of clinical PET/MRI systems To correctly identify clinical applicationsmore » that can benefit from PET/MRI To understand ongoing work to further improve the current PET/MRI technology Floris Jansen is a GE Healthcare employee.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jansen, F.

The use of integrated PET/MRI systems in clinical applications can best benefit from understanding their technological advances and limitations. The currently available clinical PET/MRI systems have their own characteristics. Thorough analyses of existing technical data and evaluation of necessary performance metrics for quality assurances could be conducted to optimize application-specific PET/MRI protocols. This Symposium will focus on technical advances and limitations of clinical PET/MRI systems, and how this exciting imaging modality can be utilized in applications that can benefit from both PET and MRI. Learning Objectives: To understand the technological advances of clinical PET/MRI systems To correctly identify clinical applicationsmore » that can benefit from PET/MRI To understand ongoing work to further improve the current PET/MRI technology Floris Jansen is a GE Healthcare employee.« less

A quasi-dense matching approach and its calibration application with Internet photos.

PubMed

Wan, Yanli; Miao, Zhenjiang; Wu, Q M Jonathan; Wang, Xifu; Tang, Zhen; Wang, Zhifei

2015-03-01

This paper proposes a quasi-dense matching approach to the automatic acquisition of camera parameters, which is required for recovering 3-D information from 2-D images. An affine transformation-based optimization model and a new matching cost function are used to acquire quasi-dense correspondences with high accuracy in each pair of views. These correspondences can be effectively detected and tracked at the sub-pixel level in multiviews with our neighboring view selection strategy. A two-layer iteration algorithm is proposed to optimize 3-D quasi-dense points and camera parameters. In the inner layer, different optimization strategies based on local photometric consistency and a global objective function are employed to optimize the 3-D quasi-dense points and camera parameters, respectively. In the outer layer, quasi-dense correspondences are resampled to guide a new estimation and optimization process of the camera parameters. We demonstrate the effectiveness of our algorithm with several experiments.

Role of Positron Emission Tomography in the Treatment of Occult Disease in Head-and-Neck Cancer: A Modeling Approach

DOE Office of Scientific and Technical Information (OSTI.GOV)

Phillips, Mark H., E-mail: markp@u.washington.ed; Smith, Wade P.; Parvathaneni, Upendra

2011-03-15

Purpose: To determine under what conditions positron emission tomography (PET) imaging will be useful in decisions regarding the use of radiotherapy for the treatment of clinically occult lymph node metastases in head-and-neck cancer. Methods and Materials: A decision model of PET imaging and its downstream effects on radiotherapy outcomes was constructed using an influence diagram. This model included the sensitivity and specificity of PET, as well as the type and stage of the primary tumor. These parameters were varied to determine the optimal strategy for imaging and therapy for different clinical situations. Maximum expected utility was the metric by whichmore » different actions were ranked. Results: For primary tumors with a low probability of lymph node metastases, the sensitivity of PET should be maximized, and 50 Gy should be delivered if PET is positive and 0 Gy if negative. As the probability for lymph node metastases increases, PET imaging becomes unnecessary in some situations, and the optimal dose to the lymph nodes increases. The model needed to include the causes of certain health states to predict current clinical practice. Conclusion: The model demonstrated the ability to reproduce expected outcomes for a range of tumors and provided recommendations for different clinical situations. The differences between the optimal policies and current clinical practice are likely due to a disparity between stated clinical decision processes and actual decision making by clinicians.« less

Artifacts in digital coincidence timing

DOE PAGES

Moses, W. W.; Peng, Q.

2014-10-16

Digital methods are becoming increasingly popular for measuring time differences, and are the de facto standard in PET cameras. These methods usually include a master system clock and a (digital) arrival time estimate for each detector that is obtained by comparing the detector output signal to some reference portion of this clock (such as the rising edge). Time differences between detector signals are then obtained by subtracting the digitized estimates from a detector pair. A number of different methods can be used to generate the digitized arrival time of the detector output, such as sending a discriminator output into amore » time to digital converter (TDC) or digitizing the waveform and applying a more sophisticated algorithm to extract a timing estimator.All measurement methods are subject to error, and one generally wants to minimize these errors and so optimize the timing resolution. A common method for optimizing timing methods is to measure the coincidence timing resolution between two timing signals whose time difference should be constant (such as detecting gammas from positron annihilation) and selecting the method that minimizes the width of the distribution (i.e. the timing resolution). Unfortunately, a common form of error (a nonlinear transfer function) leads to artifacts that artificially narrow this resolution, which can lead to erroneous selection of the 'optimal' method. In conclusion, the purpose of this note is to demonstrate the origin of this artifact and suggest that caution should be used when optimizing time digitization systems solely on timing resolution minimization.« less

Artifacts in digital coincidence timing

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moses, W. W.; Peng, Q.

Digital methods are becoming increasingly popular for measuring time differences, and are the de facto standard in PET cameras. These methods usually include a master system clock and a (digital) arrival time estimate for each detector that is obtained by comparing the detector output signal to some reference portion of this clock (such as the rising edge). Time differences between detector signals are then obtained by subtracting the digitized estimates from a detector pair. A number of different methods can be used to generate the digitized arrival time of the detector output, such as sending a discriminator output into amore » time to digital converter (TDC) or digitizing the waveform and applying a more sophisticated algorithm to extract a timing estimator.All measurement methods are subject to error, and one generally wants to minimize these errors and so optimize the timing resolution. A common method for optimizing timing methods is to measure the coincidence timing resolution between two timing signals whose time difference should be constant (such as detecting gammas from positron annihilation) and selecting the method that minimizes the width of the distribution (i.e. the timing resolution). Unfortunately, a common form of error (a nonlinear transfer function) leads to artifacts that artificially narrow this resolution, which can lead to erroneous selection of the 'optimal' method. In conclusion, the purpose of this note is to demonstrate the origin of this artifact and suggest that caution should be used when optimizing time digitization systems solely on timing resolution minimization.« less

High-precision method of binocular camera calibration with a distortion model.

PubMed

Li, Weimin; Shan, Siyu; Liu, Hui

2017-03-10

A high-precision camera calibration method for binocular stereo vision system based on a multi-view template and alternative bundle adjustment is presented in this paper. The proposed method could be achieved by taking several photos on a specially designed calibration template that has diverse encoded points in different orientations. In this paper, the method utilized the existing algorithm used for monocular camera calibration to obtain the initialization, which involves a camera model, including radial lens distortion and tangential distortion. We created a reference coordinate system based on the left camera coordinate to optimize the intrinsic parameters of left camera through alternative bundle adjustment to obtain optimal values. Then, optimal intrinsic parameters of the right camera can be obtained through alternative bundle adjustment when we create a reference coordinate system based on the right camera coordinate. We also used all intrinsic parameters that were acquired to optimize extrinsic parameters. Thus, the optimal lens distortion parameters and intrinsic and extrinsic parameters were obtained. Synthetic and real data were used to test the method. The simulation results demonstrate that the maximum mean absolute relative calibration errors are about 3.5e-6 and 1.2e-6 for the focal length and the principal point, respectively, under zero-mean Gaussian noise with 0.05 pixels standard deviation. The real result shows that the reprojection error of our model is about 0.045 pixels with the relative standard deviation of 1.0e-6 over the intrinsic parameters. The proposed method is convenient, cost-efficient, highly precise, and simple to carry out.

A Comparison of Four-Image Reconstruction Algorithms for 3-D PET Imaging of MDAPET Camera Using Phantom Data

NASA Astrophysics Data System (ADS)

Baghaei, H.; Wong, Wai-Hoi; Uribe, J.; Li, Hongdi; Wang, Yu; Liu, Yaqiang; Xing, Tao; Ramirez, R.; Xie, Shuping; Kim, Soonseok

2004-10-01

We compared two fully three-dimensional (3-D) image reconstruction algorithms and two 3-D rebinning algorithms followed by reconstruction with a two-dimensional (2-D) filtered-backprojection algorithm for 3-D positron emission tomography (PET) imaging. The two 3-D image reconstruction algorithms were ordered-subsets expectation-maximization (3D-OSEM) and 3-D reprojection (3DRP) algorithms. The two rebinning algorithms were Fourier rebinning (FORE) and single slice rebinning (SSRB). The 3-D projection data used for this work were acquired with a high-resolution PET scanner (MDAPET) with an intrinsic transaxial resolution of 2.8 mm. The scanner has 14 detector rings covering an axial field-of-view of 38.5 mm. We scanned three phantoms: 1) a uniform cylindrical phantom with inner diameter of 21.5 cm; 2) a uniform 11.5-cm cylindrical phantom with four embedded small hot lesions with diameters of 3, 4, 5, and 6 mm; and 3) the 3-D Hoffman brain phantom with three embedded small hot lesion phantoms with diameters of 3, 5, and 8.6 mm in a warm background. Lesions were placed at different radial and axial distances. We evaluated the different reconstruction methods for MDAPET camera by comparing the noise level of images, contrast recovery, and hot lesion detection, and visually compared images. We found that overall the 3D-OSEM algorithm, especially when images post filtered with the Metz filter, produced the best results in terms of contrast-noise tradeoff, and detection of hot spots, and reproduction of brain phantom structures. Even though the MDAPET camera has a relatively small maximum axial acceptance (/spl plusmn/5 deg), images produced with the 3DRP algorithm had slightly better contrast recovery and reproduced the structures of the brain phantom slightly better than the faster 2-D rebinning methods.

Erroneous cardiac ECG-gated PET list-mode trigger events can be retrospectively identified and replaced by an offline reprocessing approach: first results in rodents

NASA Astrophysics Data System (ADS)

Böning, Guido; Todica, Andrei; Vai, Alessandro; Lehner, Sebastian; Xiong, Guoming; Mille, Erik; Ilhan, Harun; la Fougère, Christian; Bartenstein, Peter; Hacker, Marcus

2013-11-01

The assessment of left ventricular function, wall motion and myocardial viability using electrocardiogram (ECG)-gated [18F]-FDG positron emission tomography (PET) is widely accepted in human and in preclinical small animal studies. The nonterminal and noninvasive approach permits repeated in vivo evaluations of the same animal, facilitating the assessment of temporal changes in disease or therapy response. Although well established, gated small animal PET studies can contain erroneous gating information, which may yield to blurred images and false estimation of functional parameters. In this work, we present quantitative and visual quality control (QC) methods to evaluate the accuracy of trigger events in PET list-mode and physiological data. Left ventricular functional analysis is performed to quantify the effect of gating errors on the end-systolic and end-diastolic volumes, and on the ejection fraction (EF). We aim to recover the cardiac functional parameters by the application of the commonly established heart rate filter approach using fixed ranges based on a standardized population. In addition, we propose a fully reprocessing approach which retrospectively replaces the gating information of the PET list-mode file with appropriate list-mode decoding and encoding software. The signal of a simultaneously acquired ECG is processed using standard MATLAB vector functions, which can be individually adapted to reliably detect the R-peaks. Finally, the new trigger events are inserted into the PET list-mode file. A population of 30 mice with various health statuses was analyzed and standard cardiac parameters such as mean heart rate (119 ms ± 11.8 ms) and mean heart rate variability (1.7 ms ± 3.4 ms) derived. These standard parameter ranges were taken into account in the QC methods to select a group of nine optimal gated and a group of eight sub-optimal gated [18F]-FDG PET scans of mice from our archive. From the list-mode files of the optimal gated group, we randomly deleted various fractions (5% to 60%) of contained trigger events to generate a corrupted group. The filter approach was capable to correct the corrupted group and yield functional parameters with no significant difference to the optimal gated group. We successfully demonstrated the potential of the fully reprocessing approach by applying it to the sub-optimal group, where the functional parameters were significantly improved after reprocessing (mean EF from 41% ± 16% to 60% ± 13%). When applied to the optimal gated group the fully reprocessing approach did not alter the functional parameters significantly (mean EF from 64% ± 8% to 64 ± 7%). This work presents methods to determine and quantify erroneous gating in small animal gated [18F]-FDG PET scans. We demonstrate the importance of a quality check for cardiac triggering contained in PET list-mode data and the benefit of optionally reprocessing the fully recorded physiological information to retrospectively modify or fully replace the cardiac triggering in PET list-mode data. We aim to provide a preliminary guideline of how to proceed in the presence of errors and demonstrate that offline reprocessing by filtering erroneous trigger events and retrospective gating by ECG processing is feasible. Future work will focus on the extension by additional QC methods, which may exploit the amplitude of trigger events and ECG signal by means of pattern recognition. Furthermore, we aim to transfer the proposed QC methods and the fully reprocessing approach to human myocardial PET/CT.

Maximizing the Performance of Automated Low Cost All-sky Cameras

NASA Technical Reports Server (NTRS)

Bettonvil, F.

2011-01-01

Thanks to the wide spread of digital camera technology in the consumer market, a steady increase in the number of active All-sky camera has be noticed European wide. In this paper I look into the details of such All-sky systems and try to optimize the performance in terms of accuracy of the astrometry, the velocity determination and photometry. Having autonomous operation in mind, suggestions are done for the optimal low cost All-sky camera.

Monte Carlo simulations of GeoPET experiments: 3D images of tracer distributions (18F, 124I and 58Co) in Opalinus clay, anhydrite and quartz

NASA Astrophysics Data System (ADS)

Zakhnini, Abdelhamid; Kulenkampff, Johannes; Sauerzapf, Sophie; Pietrzyk, Uwe; Lippmann-Pipke, Johanna

2013-08-01

Understanding conservative fluid flow and reactive tracer transport in soils and rock formations requires quantitative transport visualization methods in 3D+t. After a decade of research and development we established the GeoPET as a non-destructive method with unrivalled sensitivity and selectivity, with due spatial and temporal resolution by applying Positron Emission Tomography (PET), a nuclear medicine imaging method, to dense rock material. Requirements for reaching the physical limit of image resolution of nearly 1 mm are (a) a high-resolution PET-camera, like our ClearPET scanner (Raytest), and (b) appropriate correction methods for scatter and attenuation of 511 keV—photons in the dense geological material. The latter are by far more significant in dense geological material than in human and small animal body tissue (water). Here we present data from Monte Carlo simulations (MCS) reflecting selected GeoPET experiments. The MCS consider all involved nuclear physical processes of the measurement with the ClearPET-system and allow us to quantify the sensitivity of the method and the scatter fractions in geological media as function of material (quartz, Opalinus clay and anhydrite compared to water), PET isotope (18F, 58Co and 124I), and geometric system parameters. The synthetic data sets obtained by MCS are the basis for detailed performance assessment studies allowing for image quality improvements. A scatter correction method is applied exemplarily by subtracting projections of simulated scattered coincidences from experimental data sets prior to image reconstruction with an iterative reconstruction process.

Role for positron emission tomography in skeletal diseases.

PubMed

Duet, Michèle; Pouchot, Jacques; Lioté, Frédéric; Faraggi, Marc

2007-01-01

Imaging plays a prominent role in the diagnosis and management of rheumatic diseases. Conventional imaging methods provide high-resolution structural information but usually fail to distinguish between active lesions and residual changes. Positron emission tomography (PET) with the tracer 18F-fluorodeoxyglucose (18F-FDG) was recently introduced into clinical practice as a means of obtaining information on both structure and metabolic activity. 18F-FDG-PET is widely used in oncology and may be valuable in patients with infections or inflammatory diseases, most notably vasculitis. Although encouraging results have been published, the number of studies remains small, as 18F-FDG-PET is an expensive investigation that is not available everywhere. Further work is needed to determine the cost-effectiveness ratio of 18F-FDG-PET in patients with infections or inflammatory diseases. Imaging plays a prominent role in the diagnosis and management of many musculoskeletal diseases. Although considerable progress has been made recently, the structural information supplied by conventional imaging methods is inadequate in some patients. Positron emission tomography (PET) after injection of 18fluorodeoxyglucose (18F-FDG) provides information on tissue metabolism. The usefulness of 18F-FDG-PET in oncology is now widely recognized. Other uses are emerging, in part thanks to the development of new cameras that combine dedicated detectors and an X-scanner in order to ensure accurate three-dimensional localization of metabolically active lesions. However, the exact role for 18F-FDG-PET needs to be studied in larger populations of patients.

Development of a small prototype for a proof-of-concept of OpenPET imaging

NASA Astrophysics Data System (ADS)

Yamaya, Taiga; Yoshida, Eiji; Inaniwa, Taku; Sato, Shinji; Nakajima, Yasunori; Wakizaka, Hidekatsu; Kokuryo, Daisuke; Tsuji, Atsushi; Mitsuhashi, Takayuki; Kawai, Hideyuki; Tashima, Hideaki; Nishikido, Fumihiko; Inadama, Naoko; Murayama, Hideo; Haneishi, Hideaki; Suga, Mikio; Kinouchi, Shoko

2011-02-01

The OpenPET geometry is our new idea to visualize a physically opened space between two detector rings. In this paper, we developed the first small prototype to show a proof-of-concept of OpenPET imaging. Two detector rings of 110 mm diameter and 42 mm axial length were placed with a gap of 42 mm. The basic imaging performance was confirmed through phantom studies; the open imaging was realized at the cost of slight loss of axial resolution and 24% loss of sensitivity. For a proof-of-concept of PET image-guided radiation therapy, we carried out the in-beam tests with 11C radioactive beam irradiation in the heavy ion medical accelerator in Chiba to visualize in situ distribution of primary particles stopped in a phantom. We showed that PET images corresponding to dose distribution were obtained. For an initial proof-of-concept of real-time multimodal imaging, we measured a tumor-inoculated mouse with 18F-FDG, and an optical image of the mouse body surface was taken during the PET measurement by inserting a digital camera in the ring gap. We confirmed that the tumor in the gap was clearly visualized. The result also showed the extension effect of an axial field-of-view (FOV); a large axial FOV of 126 mm was obtained with the detectors that originally covered only an 84 mm axial FOV. In conclusion, our initial imaging studies showed promising performance of the OpenPET.

Development of a simultaneous optical/PET imaging system for awake mice

NASA Astrophysics Data System (ADS)

Takuwa, Hiroyuki; Ikoma, Yoko; Yoshida, Eiji; Tashima, Hideaki; Wakizaka, Hidekatsu; Shinaji, Tetsuya; Yamaya, Taiga

2016-09-01

Simultaneous measurements of multiple physiological parameters are essential for the study of brain disease mechanisms and the development of suitable therapies to treat them. In this study, we developed a measurement system for simultaneous optical imaging and PET for awake mice. The key elements of this system are the OpenPET, optical imaging and fixation apparatus for an awake mouse. The OpenPET is our original open-type PET geometry, which can be used in combination with another device because of the easily accessible open space of the former. A small prototype of the axial shift single-ring OpenPET was used. The objective lens for optical imaging with a mounted charge-coupled device camera was placed inside the open space of the AS-SROP. Our original fixation apparatus to hold an awake mouse was also applied. As a first application of this system, simultaneous measurements of cerebral blood flow (CBF) by laser speckle imaging (LSI) and [11C]raclopride-PET were performed under control and 5% CO2 inhalation (hypercapnia) conditions. Our system successfully obtained the CBF and [11C]raclopride radioactivity concentration simultaneously. Accumulation of [11C]raclopride was observed in the striatum where the density of dopamine D2 receptors is high. LSI measurements could be stably performed for more than 60 minutes. Increased CBF induced by hypercapnia was observed while CBF under the control condition was stable. We concluded that our imaging system should be useful for investigating the mechanisms of brain diseases in awake animal models.

A philosophy for CNS radiotracer design.

PubMed

Van de Bittner, Genevieve C; Ricq, Emily L; Hooker, Jacob M

2014-10-21

Decades after its discovery, positron emission tomography (PET) remains the premier tool for imaging neurochemistry in living humans. Technological improvements in radiolabeling methods, camera design, and image analysis have kept PET in the forefront. In addition, the use of PET imaging has expanded because researchers have developed new radiotracers that visualize receptors, transporters, enzymes, and other molecular targets within the human brain. However, of the thousands of proteins in the central nervous system (CNS), researchers have successfully imaged fewer than 40 human proteins. To address the critical need for new radiotracers, this Account expounds on the decisions, strategies, and pitfalls of CNS radiotracer development based on our current experience in this area. We discuss the five key components of radiotracer development for human imaging: choosing a biomedical question, selection of a biological target, design of the radiotracer chemical structure, evaluation of candidate radiotracers, and analysis of preclinical imaging. It is particularly important to analyze the market of scientists or companies who might use a new radiotracer and carefully select a relevant biomedical question(s) for that audience. In the selection of a specific biological target, we emphasize how target localization and identity can constrain this process and discuss the optimal target density and affinity ratios needed for binding-based radiotracers. In addition, we discuss various PET test-retest variability requirements for monitoring changes in density, occupancy, or functionality for new radiotracers. In the synthesis of new radiotracer structures, high-throughput, modular syntheses have proved valuable, and these processes provide compounds with sites for late-stage radioisotope installation. As a result, researchers can manage the time constraints associated with the limited half-lives of isotopes. In order to evaluate brain uptake, a number of methods are available to predict bioavailability, blood-brain barrier (BBB) permeability, and the associated issues of nonspecific binding and metabolic stability. To evaluate the synthesized chemical library, researchers need to consider high-throughput affinity assays, the analysis of specific binding, and the importance of fast binding kinetics. Finally, we describe how we initially assess preclinical radiotracer imaging, using brain uptake, specific binding, and preliminary kinetic analysis to identify promising radiotracers that may be useful for human brain imaging. Although we discuss these five design components separately and linearly in this Account, in practice we develop new PET-based radiotracers using these design components nonlinearly and iteratively to develop new compounds in the most efficient way possible.

Parametric PET/MR Fusion Imaging to Differentiate Aggressive from Indolent Primary Prostate Cancer with Application for Image-Guided Prostate Cancer Biopsies

DTIC Science & Technology

2014-10-01

Unlimited 13. SUPPLEMENTARY NOTES 14. ABSTRACT The study investigates whether fusion PET/MRI imaging with 18F- choline PET/CT and...imaging with 18F- choline PET/CT and diffusion-weighted MRI can be successfully applied to target prostate cancer using image-guided prostate...Completed task. The 18F- choline synthesis was implemented and optimized for routine radiotracer production. RDRC committee approval as part of the IRB

MO-FG-207-01: Technological Advances and Challenges: Experience with the First Integrated Whole-Body PET/MRI

DOE Office of Scientific and Technical Information (OSTI.GOV)

Laforest, R.

2015-06-15

The use of integrated PET/MRI systems in clinical applications can best benefit from understanding their technological advances and limitations. The currently available clinical PET/MRI systems have their own characteristics. Thorough analyses of existing technical data and evaluation of necessary performance metrics for quality assurances could be conducted to optimize application-specific PET/MRI protocols. This Symposium will focus on technical advances and limitations of clinical PET/MRI systems, and how this exciting imaging modality can be utilized in applications that can benefit from both PET and MRI. Learning Objectives: To understand the technological advances of clinical PET/MRI systems To correctly identify clinical applicationsmore » that can benefit from PET/MRI To understand ongoing work to further improve the current PET/MRI technology Floris Jansen is a GE Healthcare employee.« less

A machine learning method for fast and accurate characterization of depth-of-interaction gamma cameras

NASA Astrophysics Data System (ADS)

Pedemonte, Stefano; Pierce, Larry; Van Leemput, Koen

2017-11-01

Measuring the depth-of-interaction (DOI) of gamma photons enables increasing the resolution of emission imaging systems. Several design variants of DOI-sensitive detectors have been recently introduced to improve the performance of scanners for positron emission tomography (PET). However, the accurate characterization of the response of DOI detectors, necessary to accurately measure the DOI, remains an unsolved problem. Numerical simulations are, at the state of the art, imprecise, while measuring directly the characteristics of DOI detectors experimentally is hindered by the impossibility to impose the depth-of-interaction in an experimental set-up. In this article we introduce a machine learning approach for extracting accurate forward models of gamma imaging devices from simple pencil-beam measurements, using a nonlinear dimensionality reduction technique in combination with a finite mixture model. The method is purely data-driven, not requiring simulations, and is applicable to a wide range of detector types. The proposed method was evaluated both in a simulation study and with data acquired using a monolithic gamma camera designed for PET (the cMiCE detector), demonstrating the accurate recovery of the DOI characteristics. The combination of the proposed calibration technique with maximum- a posteriori estimation of the coordinates of interaction provided a depth resolution of  ≈1.14 mm for the simulated PET detector and  ≈1.74 mm for the cMiCE detector. The software and experimental data are made available at http://occiput.mgh.harvard.edu/depthembedding/.

68Ga-EDTA PET/CT imaging and plasma clearance for glomerular filtration rate quantification: comparison to conventional 51Cr-EDTA.

PubMed

Hofman, Michael; Binns, David; Johnston, Val; Siva, Shankar; Thompson, Mick; Eu, Peter; Collins, Marnie; Hicks, Rodney J

2015-03-01

Glomerular filtration rate (GFR) can accurately be determined using (51)Cr-ethylenediaminetetraacetic acid (EDTA) plasma clearance counting but is time-consuming and requires technical skills and equipment not always available in imaging departments. (68)Ga-EDTA can be readily available using an onsite generator, and PET/CT enables both imaging of renal function and accurate camera-based quantitation of clearance of activity from blood and its appearance in the urine. This study aimed to assess agreement between (68)Ga-EDTA GFR ((68)Ga-GFR) and (51)Cr-EDTA GFR ((51)Cr-GFR), using serial plasma sampling and PET imaging. (68)Ga-EDTA and (51)Cr-EDTA were injected concurrently in 31 patients. Dynamic PET/CT encompassing the kidneys was acquired for 10 min followed by 3 sequential 3-min multibed step acquisitions from kidneys to bladder. PET quantification was performed using renal activity at 1-2 min (PETinitial), renal excretion at 2-10 min (PETearly), and, subsequently, urinary excretion into the collecting system and bladder (PETlate). Plasma sampling at 2, 3, and 4 h was performed, with (68)Ga followed by (51)Cr counting after positron decay. The level of agreement for GFR determination was calculated using a Bland-Altman plot and Pearson correlation coefficient (PCC). (51)Cr-GFR ranged from 10 to 220 mL/min (mean, 85 mL/min). There was good agreement between (68)Ga-GFR and (51)Cr-GFR using serial plasma sampling, with a Bland-Altman bias of -14 ± 20 mL/min and a PCC of 0.94 (95% confidence interval, 0.88-0.97). Of the 3 methods used for camera-based quantification, the strongest correlation was for plasma sampling-derived GFR with PETlate (PCC of 0.90; 95% confidence interval, 0.80-0.95). (68)Ga-GFR agreed well with (51)Cr-GFR for estimation of GFR using serial plasma counting. PET dynamic imaging provides a method to estimate GFR without plasma sampling, with the additional advantage of enabling renal imaging in a single study. Additional validation in a larger cohort is warranted to further assess utility. © 2015 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

Methods for increasing the sensitivity of gamma-ray imagers

DOEpatents

Mihailescu, Lucian [Pleasanton, CA; Vetter, Kai M [Alameda, CA; Chivers, Daniel H [Fremont, CA

2012-02-07

Methods are presented that increase the position resolution and granularity of double sided segmented semiconductor detectors. These methods increase the imaging resolution capability of such detectors, either used as Compton cameras, or as position sensitive radiation detectors in imagers such as SPECT, PET, coded apertures, multi-pinhole imagers, or other spatial or temporal modulated imagers.

Systems for increasing the sensitivity of gamma-ray imagers

DOEpatents

Mihailescu, Lucian; Vetter, Kai M.; Chivers, Daniel H.

2012-12-11

Systems that increase the position resolution and granularity of double sided segmented semiconductor detectors are provided. These systems increase the imaging resolution capability of such detectors, either used as Compton cameras, or as position sensitive radiation detectors in imagers such as SPECT, PET, coded apertures, multi-pinhole imagers, or other spatial or temporal modulated imagers.

Navigating surgical fluorescence cameras using near-infrared optical tracking.

PubMed

van Oosterom, Matthias; den Houting, David; van de Velde, Cornelis; van Leeuwen, Fijs

2018-05-01

Fluorescence guidance facilitates real-time intraoperative visualization of the tissue of interest. However, due to attenuation, the application of fluorescence guidance is restricted to superficial lesions. To overcome this shortcoming, we have previously applied three-dimensional surgical navigation to position the fluorescence camera in reach of the superficial fluorescent signal. Unfortunately, in open surgery, the near-infrared (NIR) optical tracking system (OTS) used for navigation also induced an interference during NIR fluorescence imaging. In an attempt to support future implementation of navigated fluorescence cameras, different aspects of this interference were characterized and solutions were sought after. Two commercial fluorescence cameras for open surgery were studied in (surgical) phantom and human tissue setups using two different NIR OTSs and one OTS simulating light-emitting diode setup. Following the outcome of these measurements, OTS settings were optimized. Measurements indicated the OTS interference was caused by: (1) spectral overlap between the OTS light and camera, (2) OTS light intensity, (3) OTS duty cycle, (4) OTS frequency, (5) fluorescence camera frequency, and (6) fluorescence camera sensitivity. By optimizing points 2 to 4, navigation of fluorescence cameras during open surgery could be facilitated. Optimization of the OTS and camera compatibility can be used to support navigated fluorescence guidance concepts. (2018) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE).

Optimization of PET-MR Registrations for Nonhuman Primates Using Mutual Information Measures: A Multi-Transform Method (MTM)

PubMed Central

Sandiego, Christine M.; Weinzimmer, David; Carson, Richard E.

2012-01-01

An important step in PET brain kinetic analysis is the registration of functional data to an anatomical MR image. Typically, PET-MR registrations in nonhuman primate neuroreceptor studies used PET images acquired early post-injection, (e.g., 0–10 min) to closely resemble the subject’s MR image. However, a substantial fraction of these registrations (~25%) fail due to the differences in kinetics and distribution for various radiotracer studies and conditions (e.g., blocking studies). The Multi-Transform Method (MTM) was developed to improve the success of registrations between PET and MR images. Two algorithms were evaluated, MTM-I and MTM-II. The approach involves creating multiple transformations by registering PET images of different time intervals, from a dynamic study, to a single reference (i.e., MR image) (MTM-I) or to multiple reference images (i.e., MR and PET images pre-registered to the MR) (MTM-II). Normalized mutual information was used to compute similarity between the transformed PET images and the reference image(s) to choose the optimal transformation. This final transformation is used to map the dynamic dataset into the animal’s anatomical MR space, required for kinetic analysis. The chosen transformed from MTM-I and MTM-II were evaluated using visual rating scores to assess the quality of spatial alignment between the resliced PET and reference. One hundred twenty PET datasets involving eleven different tracers from 3 different scanners were used to evaluate the MTM algorithms. Studies were performed with baboons and rhesus monkeys on the HR+, HRRT, and Focus-220. Successful transformations increased from 77.5%, 85.8%, to 96.7% using the 0–10 min method, MTM-I, and MTM-II, respectively, based on visual rating scores. The Multi-Transform Methods proved to be a robust technique for PET-MR registrations for a wide range of PET studies. PMID:22926293

Instrumentation in molecular imaging.

PubMed

Wells, R Glenn

2016-12-01

In vivo molecular imaging is a challenging task and no single type of imaging system provides an ideal solution. Nuclear medicine techniques like SPECT and PET provide excellent sensitivity but have poor spatial resolution. Optical imaging has excellent sensitivity and spatial resolution, but light photons interact strongly with tissues and so only small animals and targets near the surface can be accurately visualized. CT and MRI have exquisite spatial resolution, but greatly reduced sensitivity. To overcome the limitations of individual modalities, molecular imaging systems often combine individual cameras together, for example, merging nuclear medicine cameras with CT or MRI to allow the visualization of molecular processes with both high sensitivity and high spatial resolution.

Comparison of dual-biomarker PIB-PET and dual-tracer PET in AD diagnosis.

PubMed

Fu, Liping; Liu, Linwen; Zhang, Jinming; Xu, Baixuan; Fan, Yong; Tian, Jiahe

2014-11-01

To identify the optimal time window for capturing perfusion information from early (11)C-PIB imaging frames (perfusion PIB, (11)C-pPIB) and to compare the performance of (18)F-FDG PET and "dual biomarker" (11)C-PIB PET [(11)C-pPIB and amyloid PIB ((11)C-aPIB)] for classification of AD, MCI and CN subjects. Forty subjects (14 CN, 12 MCI and 14 AD patients) underwent (18)F-FDG and (11)C-PIB PET studies. Pearson correlation between the (18)F-FDG image and sum of early (11)C-PIB frames was maximised to identify the optimal time window for (11)C-pPIB. The classification power of imaging parameters was evaluated with a leave-one-out validation. A 7-min time window yielded the highest correlation between (18)F-FDG and (11)C-pPIB. (11)C-pPIB and (18)F-FDG images shared a similar radioactive distribution pattern. (18)F-FDG performed better than (11)C-pPIB for the classification of both AD vs. CN and MCI vs. CN. (11)C-pPIB + (11)C-aPIB and (18)F-FDG + (11)C-aPIB yielded the highest classification accuracy for the classification of AD vs. CN, and (18)F-FDG + (11)C-aPIB had the best classification performance for the classification of MCI vs. C-pPIB could serve as a useful biomarker of rCBF for measuring neural activity and improve the diagnostic power of PET for AD in conjunction with (11)C-aPIB. (18)F-FDG and (11)C-PIB dual-tracer PET examination could better detect MCI. • Dual-tracer PET examination provides neurofunctional and neuropathological information for AD diagnosis. • The identified optimal 11C-pPIB time frames had highest correlation with 18F-FDG. • 11C-pPIB images shared a similar radioactive distribution pattern with 18F-FDG images. • 11C-pPIB can provide neurofunctional information. • Dual-tracer PET examination could better detect MCI.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lee, E; Yuan, F; Templeton, A

Purpose: The ultimate goal of radiotherapy treatment planning is to find a treatment that will yield a high tumor-control-probability(TCP) with an acceptable normal-tissue-complication probability(NTCP). Yet most treatment planning today is not based upon optimization of TCPs and NTCPs, but rather upon meeting physical dose and volume constraints defined by the planner. We design treatment plans that optimize TCP directly and contrast them with the clinical dose-based plans. PET image is incorporated to evaluate gain in TCP for dose escalation. Methods: We build a nonlinear mixed integer programming optimization model that maximizes TCP directly while satisfying the dose requirements on themore » targeted organ and healthy tissues. The solution strategy first fits the TCP function with a piecewise-linear approximation, then solves the problem that maximizes the piecewise linear approximation of TCP, and finally performs a local neighborhood search to improve the TCP value. To gauge the feasibility, characteristics, and potential benefit of PET-image guided dose escalation, initial validation consists of fifteen cervical cancer HDR patient cases. These patients have all received prior 45Gy of external radiation dose. For both escalated strategies, we consider 35Gy PTV-dose, and two variations (37Gy-boost to BTV vs 40Gy-boost) to PET-image-pockets. Results: TCP for standard clinical plans range from 59.4% - 63.6%. TCP for dose-based PET-guided escalated-dose-plan ranges from 63.8%–98.6% for all patients; whereas TCP-optimized plans achieves over 91% for all patients. There is marginal difference in TCP among those with 37Gy-boosted vs 40Gy-boosted. There is no increase in rectum and bladder dose among all plans. Conclusion: Optimizing TCP directly results in highly conformed treatment plans. The TCP-optimized plan is individualized based on the biological PET-image of the patients. The TCP-optimization framework is generalizable and has been applied successfully to other external-beam delivery modalities. A clinical trial is on-going to gauge the clinical significance. Partially supported by the National Science Foundation.« less

Diagnostic implications of a small-voxel reconstruction for loco-regional lymph node characterization in breast cancer patients using FDG-PET/CT.

PubMed

Koopman, Daniëlle; van Dalen, Jorn A; Arkies, Hester; Oostdijk, Ad H J; Francken, Anne Brecht; Bart, Jos; Slump, Cornelis H; Knollema, Siert; Jager, Pieter L

2018-01-16

We evaluated the diagnostic implications of a small-voxel reconstruction for lymph node characterization in breast cancer patients, using state-of-the-art FDG-PET/CT. We included 69 FDG-PET/CT scans from breast cancer patients. PET data were reconstructed using standard 4 × 4 × 4 mm 3 and small 2 × 2 × 2 mm 3 voxels. Two hundred thirty loco-regional lymph nodes were included, of which 209 nodes were visualised on PET/CT. All nodes were visually scored as benign or malignant, and SUV max and TB ratio (=SUV max /SUV background ) were measured. Final diagnosis was based on histological or imaging information. We determined the accuracy, sensitivity and specificity for both reconstruction methods and calculated optimal cut-off values to distinguish benign from malignant nodes. Sixty-one benign and 169 malignant lymph nodes were included. Visual evaluation accuracy was 73% (sensitivity 67%, specificity 89%) on standard-voxel images and 77% (sensitivity 78%, specificity 74%) on small-voxel images (p = 0.13). Across malignant nodes visualised on PET/CT, the small-voxel score was more often correct compared with the standard-voxel score (89 vs. 76%, p <  0.001). In benign nodes, the standard-voxel score was more often correct (89 vs. 74%, p = 0.04). Quantitative data were based on the 61 benign and 148 malignant lymph nodes visualised on PET/CT. SUVs and TB ratio were on average 3.0 and 1.6 times higher in malignant nodes compared to those in benign nodes (p <  0.001), on standard- and small-voxel PET images respectively. Small-voxel PET showed average increases in SUV max and TB ratio of typically 40% over standard-voxel PET. The optimal SUV max cut-off using standard-voxels was 1.8 (sensitivity 81%, specificity 95%, accuracy 85%) while for small-voxels, the optimal SUV max cut-off was 2.6 (sensitivity 78%, specificity 98%, accuracy 84%). Differences in accuracy were non-significant. Small-voxel PET/CT improves the sensitivity of visual lymph node characterization and provides a higher detection rate of malignant lymph nodes. However, small-voxel PET/CT also introduced more false-positive results in benign nodes. Across all nodes, differences in accuracy were non-significant. Quantitatively, small-voxel images require higher cut-off values. Readers have to adapt their reference standards.

PetIGA-MF: A multi-field high-performance toolbox for structure-preserving B-splines spaces

DOE PAGES

Sarmiento, Adel; Cortes, Adriano; Garcia, Daniel; ...

2016-10-07

We describe the development of a high-performance solution framework for isogeometric discrete differential forms based on B-splines: PetIGA-MF. Built on top of PetIGA, PetIGA-MF is a general multi-field discretization tool. To test the capabilities of our implementation, we solve different viscous flow problems such as Darcy, Stokes, Brinkman, and Navier-Stokes equations. Several convergence benchmarks based on manufactured solutions are presented assuring optimal convergence rates of the approximations, showing the accuracy and robustness of our solver.

18F-DOPA PET/CT and 68Ga-DOTANOC PET/CT scans as diagnostic tools in focal congenital hyperinsulinism: a blinded evaluation.

PubMed

Christiansen, Charlotte Dahl; Petersen, Henrik; Nielsen, Anne Lerberg; Detlefsen, Sönke; Brusgaard, Klaus; Rasmussen, Lars; Melikyan, Maria; Ekström, Klas; Globa, Evgenia; Rasmussen, Annett Helleskov; Hovendal, Claus; Christesen, Henrik Thybo

2018-02-01

Focal congenital hyperinsulinism (CHI) is curable by surgery, which is why identification of the focal lesion is crucial. We aimed to determine the use of 18F-fluoro-dihydroxyphenylalanine (18F-DOPA) PET/CT vs. 68Ga-1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic-acid-1-Nal3-octreotide (68Ga-DOTANOC) PET/CT as diagnostic tools in focal CHI. PET/CT scans of children with CHI admitted to Odense University Hospital between August 2005 and June 2016 were retrospectively evaluated visually and by their maximal standardized uptake values (SUV max ) by two independent examiners, blinded for clinical, surgical and pathological data. Pancreatic histology was used as the gold standard. For patients without surgery, the genetic profile served as the gold standard. Fifty-five CHI patients were examined by PET/CT (18F-DOPA n = 53, 68Ga-DOTANOC n = 18). Surgery was performed in 34 patients, no surgery in 21 patients. Fifty-one patients had a classifiable outcome, either by histology (n = 33, 22 focal lesions, 11 non-focal) or by genetics (n = 18, all non-focal). The predictive performance of 18F-DOPA PET/CT to identify focal CHI was identical by visual- and cut-off-based evaluation: sensitivity (95% CI) of 1 (0.85-1); specificity of 0.96 (0.82-0.99). The optimal 18F-DOPA PET SUV max ratio cut-off was 1.44 and the optimal 68Ga-DOTANOC PET SUV max cut-off was 6.77 g/ml. The area under the receiver operating curve was 0.98 (0.93-1) for 18F-DOPA PET vs. 0.71 (0.43-0.95) for 68Ga-DOTANOC PET (p < 0.03). In patients subjected to surgery, localization of the focal lesion was correct in 91%, and 100%, by 18F-DOPA PET/CT and 68Ga-DOTANOC PET/CT, respectively. 18F-DOPA PET/CT was excellent in predicting focal CHI and superior compared to 68Ga-DOTANOC PET/CT. Further use of 68GA-DOTANOC PET/CT in predicting focal CHI is discouraged.

Activity-based costing evaluation of a [(18)F]-fludeoxyglucose positron emission tomography study.

PubMed

Krug, Bruno; Van Zanten, Annie; Pirson, Anne-Sophie; Crott, Ralph; Borght, Thierry Vander

2009-10-01

The aim of the study is to use the activity-based costing approach to give a better insight in the actual cost structure of a positron emission tomography procedure (FDG-PET) by defining the constituting components and by simulating the impact of possible resource or practice changes. The cost data were obtained from the hospital administration, personnel and vendor interviews as well as from structured questionnaires. A process map separates the process in 16 patient- and non-patient-related activities, to which the detailed cost data are related. One-way sensitivity analyses shows to which degree of uncertainty the different parameters affect the individual cost and evaluate the impact of possible resource or practice changes like the acquisition of a hybrid PET/CT device, the patient throughput or the sales price of a 370MBq (18)F-FDG patient dose. The PET centre spends 73% of time in clinical activities and the resting time after injection of the tracer (42%) is the single largest departmental cost element. The tracer cost and the operational time have the most influence on cost per procedure. The analysis shows a total cost per FDG-PET ranging from 859 Euro for a BGO PET camera to 1142 Euro for a 16 slices PET-CT system, with a distribution of the resource costs in decreasing order: materials (44%), equipment (24%), wage (16%), space (6%) and hospital overhead (10%). The cost of FDG-PET is mainly influenced by the cost of the radiopharmaceutical. Therefore, the latter rather than the operational time should be reduced in order to improve its cost-effectiveness.

Optimized MLAA for quantitative non-TOF PET/MR of the brain

NASA Astrophysics Data System (ADS)

Benoit, Didier; Ladefoged, Claes N.; Rezaei, Ahmadreza; Keller, Sune H.; Andersen, Flemming L.; Højgaard, Liselotte; Hansen, Adam E.; Holm, Søren; Nuyts, Johan

2016-12-01

For quantitative tracer distribution in positron emission tomography, attenuation correction is essential. In a hybrid PET/CT system the CT images serve as a basis for generation of the attenuation map, but in PET/MR, the MR images do not have a similarly simple relationship with the attenuation map. Hence attenuation correction in PET/MR systems is more challenging. Typically either of two MR sequences are used: the Dixon or the ultra-short time echo (UTE) techniques. However these sequences have some well-known limitations. In this study, a reconstruction technique based on a modified and optimized non-TOF MLAA is proposed for PET/MR brain imaging. The idea is to tune the parameters of the MLTR applying some information from an attenuation image computed from the UTE sequences and a T1w MR image. In this MLTR algorithm, an {αj} parameter is introduced and optimized in order to drive the algorithm to a final attenuation map most consistent with the emission data. Because the non-TOF MLAA is used, a technique to reduce the cross-talk effect is proposed. In this study, the proposed algorithm is compared to the common reconstruction methods such as OSEM using a CT attenuation map, considered as the reference, and OSEM using the Dixon and UTE attenuation maps. To show the robustness and the reproducibility of the proposed algorithm, a set of 204 [18F]FDG patients, 35 [11C]PiB patients and 1 [18F]FET patient are used. The results show that by choosing an optimized value of {αj} in MLTR, the proposed algorithm improves the results compared to the standard MR-based attenuation correction methods (i.e. OSEM using the Dixon or the UTE attenuation maps), and the cross-talk and the scale problem are limited.

Optimization of transmission scan duration for 15O PET study with sequential dual tracer administration using N-index.

PubMed

Kudomi, Nobuyuki; Watabe, Hiroshi; Hayashi, Takuya; Oka, Hisashi; Miyake, Yoshinori; Iida, Hidehiro

2010-06-01

Cerebral blood flow (CBF), oxygen extraction fraction (OEF) and cerebral metabolic rate of O(2) (CMRO(2)) can be quantified by PET with the administration of H (2) (15) O and (15)O(2). Recently, a shortening in the duration of these measurements was achieved by the sequential administration of dual tracers of (15)O(2) and H (2) (15) O with PET acquisition and integration method (DARG method). A transmission scan is generally required for correcting photon attenuation in advance of PET scan. Although the DARG method can shorten the total study duration to around 30 min, the transmission scan duration has not been optimized and has possibility to shorten its duration. Our aim of this study was to determine the optimal duration for the transmission scan. We introduced 'N-index', which estimates the noise level on an image obtained by subtracting two statistically independent and physiologically equivalent images. The relationship between noise on functional images and duration of the transmission scan was investigated by N-index. We performed phantom studies to test whether the N-index reflects the pixel noise in a PET image. We also estimated the noise level by the N-index on CBF, OEF and CMRO(2) images from DARG method in clinical patients, and investigated an optimal true count of the transmission scan. We found tight correlation between pixel noise and N-index in the phantom study. By investigating relationship between the transmission scan duration and N-index value for the functional images by DARG method, we revealed that the transmission data with true counts of more than 40 Mcounts results in CBF, OEF, and CMRO(2) images of reasonable quantitative accuracy and quality. The present study suggests that further shortening of DARG measurement is possible by abridging the transmission scan. The N-index could be used to determine the optimal measurement condition when examining the quality of image.

F18-FDG coincidence-PET in patients with suspected gynecological malignancy.

PubMed

Zor, E; Stokkel, M P; Ozalp, S; Vardareli, E; Yalçin, O Tarik; Ak, I

2006-07-01

To assess the role of F18-FDG imaging with a dual-head coincidence mode gamma camera (Co-PET) in identifying malignant tumors in patients with a suspicious adnexal mass depicted by conventional imaging methods. F18-FDG Co-PET was performed preoperatively in 18 women (mean age 56.38 years) with suspected malignant gynecologic tumors according to clinical and abdomino-pelvic/transvaginal ultrasound or computed tomography findings. Exploratory laparotomy was performed in all patients within the 10 days post-F18-FDG Co-PET study, and the definitive diagnosis of the adnexal masses was established by histopathological examination. Histopathological examinations of the surgically excised adnexal masses revealed eight malignant, one borderline, and nine benign neoplastic tumors. Four benign tumors had no F18-FDG uptake, while the remaining five tumors, all leiomyomas, showed mild FDG accumulation. Eight malignant tumors showed intense F18-FDG uptake. Sensitivity, specificity, PPV, and NPV of F18-FDG co-PET in differentiating benign from malign adnexal masses were 88%, 44%, 61%, and 80%, respectively. Tumor to background ratios (T/B) in benign lesions (2.04 +/- 0.27) were significantly lower than in malignant lesions (7.4 +/- 0.99). F18-FDG Co-PET is of clinical value when assessing suspicious malignant adnexal masses. False-negative F18-FDG results might arise from borderline disease. Moderate F18-FDG uptake in leiomyomas can result false-positive, but T/B ratios may be helpful in such cases.

WE-H-207A-06: Hypoxia Quantification in Static PET Images: The Signal in the Noise

DOE Office of Scientific and Technical Information (OSTI.GOV)

Keller, H; Yeung, I; Milosevic, M

2016-06-15

Purpose: Quantification of hypoxia from PET images is of considerable clinical interest. In the absence of dynamic PET imaging the hypoxic fraction (HF) of a tumor has to be estimated from voxel values of activity concentration of a radioactive hypoxia tracer. This work is part of an effort to standardize quantification of tumor hypoxic fraction from PET images. Methods: A simple hypoxia imaging model in the tumor was developed. The distribution of the tracer activity was described as the sum of two different probability distributions, one for the normoxic (and necrotic), the other for the hypoxic voxels. The widths ofmore » the distributions arise due to variability of the transport, tumor tissue inhomogeneity, tracer binding kinetics, and due to PET image noise. Quantification of HF was performed for various levels of variability using two different methodologies: a) classification thresholds between normoxic and hypoxic voxels based on a non-hypoxic surrogate (muscle), and b) estimation of the (posterior) probability distributions based on maximizing likelihood optimization that does not require a surrogate. Data from the hypoxia imaging model and from 27 cervical cancer patients enrolled in a FAZA PET study were analyzed. Results: In the model, where the true value of HF is known, thresholds usually underestimate the value for large variability. For the patients, a significant uncertainty of the HF values (an average intra-patient range of 17%) was caused by spatial non-uniformity of image noise which is a hallmark of all PET images. Maximum likelihood estimation (MLE) is able to directly optimize for the weights of both distributions, however, may suffer from poor optimization convergence. For some patients, MLE-based HF values showed significant differences to threshold-based HF-values. Conclusion: HF-values depend critically on the magnitude of the different sources of tracer uptake variability. A measure of confidence should also be reported.« less

A novel SPECT camera for molecular imaging of the prostate

NASA Astrophysics Data System (ADS)

Cebula, Alan; Gilland, David; Su, Li-Ming; Wagenaar, Douglas; Bahadori, Amir

2011-10-01

The objective of this work is to develop an improved SPECT camera for dedicated prostate imaging. Complementing the recent advancements in agents for molecular prostate imaging, this device has the potential to assist in distinguishing benign from aggressive cancers, to improve site-specific localization of cancer, to improve accuracy of needle-guided prostate biopsy of cancer sites, and to aid in focal therapy procedures such as cryotherapy and radiation. Theoretical calculations show that the spatial resolution/detection sensitivity of the proposed SPECT camera can rival or exceed 3D PET and further signal-to-noise advantage is attained with the better energy resolution of the CZT modules. Based on photon transport simulation studies, the system has a reconstructed spatial resolution of 4.8 mm with a sensitivity of 0.0001. Reconstruction of a simulated prostate distribution demonstrates the focal imaging capability of the system.

Current Status of Nuclear Medicine Practice in the Middle East.

PubMed

Paez, Diana; Becic, Tarik; Bhonsle, Uday; Jalilian, Amir R; Nuñez-Miller, Rodolfo; Osso, Joao Alberto

2016-07-01

The practice of nuclear medicine (NM) in the Middle East region has experienced an important growth in the last 2 decades and has become crucial in providing healthcare to the region's population of about 395 million people. Even though there are some countries in which the services provided are limited to basic coverage of studies with (99m)Tc and (131)I, most have well-established practices covering most of the available studies in this medical specialty; this is the case in for example, Iran, Israel, Kuwait, Saudi Arabia, and Turkey. According to data provided by the NM professionals in the 17 countries included in the present publication, which was collected by the International Atomic Energy Agency in 2015, the total number of gamma cameras in the region is 910 with an average of 2.3 gamma cameras per million inhabitants. Out of these, 107 cameras, or 12%, are SPECT/CT cameras. There are 194 operating PET/CT scanners, translating to one PET/CT scanner for 2.04 million people on average. The availability of PET/CT scanners in relation to population is the highest in Lebanon and Kuwait, with 2.2 and 1.7 scanners per million people, respectively. There is a total of 628 NM centers in the 17 countries, whereas most NM centers belong to the public healthcare system and in most of the countries are widely spread and not confined exclusively to capital cities. As for the radionuclide therapies, (131)I is used regularly in diagnostic workup as well as in therapeutic applications in all the countries included in this analysis. Only five countries have the capability of assembling (99)Mo-(99m)Tc generators (Egypt, Iran, Saudi Arabia, Israel, and Turkey), and cold kits are produced in several countries. Although there are no capabilities in the region to produce (99)Mo from nuclear reactors, a total of 46 cyclotrons are operated for production of PET radionuclides. The most widely used PET tracer in the region is (18)F-FDG followed by (18)F-NaF; concomitantly, the availability of (68)Ge-(68)Ga generators is increasing and studies involving prostate-specific membrane antigen or DOTA-chelated peptides or both are performed in at least seven countries. Although therapeutic radionuclide agents are mostly imported from outside the region, this does not limit the availability of therapies with (90)Y, (153)Sm, (177)Lu, (131)I, (188)Re, and (89)Sr. Nevertheless, therapies based on alpha particle emitters are still largely not available in the region and are currently only available in Israel and Turkey. Regarding human resources, according to the data provided there are 1157 NM physicians, 1953 technologists, 586 medical physicists, and 173 radiopharmacists or radiochemists in the region. Approximately half of all available human resources are accounted for by Turkey. The region has great potential for expanding the applications of NM; this becomes especially important in view of the high prevalence of non-communicable diseases. Further increasing awareness of the clinical applications of NM in healthcare and strengthening technical and human capacities including the establishment of training programs for all professionals and disciplines in the field are recognized as key components in advancing the practice of NM in the Middle East. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

Evaluation of Multimodal Imaging Biomarkers of Prostate Cancer

DTIC Science & Technology

2015-09-01

and PET images. Figure 2 highlights the dynamic uptake of TSPO as compared to muscle. Across 60 minutes the %ID/cc continues to increase which is...p53 double null mutant mouse model. Towards that end, we have successfully acquired anatomic MRI and PET data in orthotopic tumors within the Pten...castration resistant prostate cancer, MRI, PET , FDHT, image optimization 16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF ABSTRACT 18. NUMBER OF PAGES

Optimum color filters for CCD digital cameras

NASA Astrophysics Data System (ADS)

Engelhardt, Kai; Kunz, Rino E.; Seitz, Peter; Brunner, Harald; Knop, Karl

1993-12-01

As part of the ESPRIT II project No. 2103 (MASCOT) a high performance prototype color CCD still video camera was developed. Intended for professional usage such as in the graphic arts, the camera provides a maximum resolution of 3k X 3k full color pixels. A high colorimetric performance was achieved through specially designed dielectric filters and optimized matrixing. The color transformation was obtained by computer simulation of the camera system and non-linear optimization which minimized the perceivable color errors as measured in the 1976 CIELUV uniform color space for a set of about 200 carefully selected test colors. The color filters were designed to allow perfect colorimetric reproduction in principle and at the same time with imperceptible color noise and with special attention to fabrication tolerances. The camera system includes a special real-time digital color processor which carries out the color transformation. The transformation can be selected from a set of sixteen matrices optimized for different illuminants and output devices. Because the actual filter design was based on slightly incorrect data the prototype camera showed a mean colorimetric error of 2.7 j.n.d. (CIELUV) in experiments. Using correct input data in the redesign of the filters, a mean colorimetric error of only 1 j.n.d. (CIELUV) seems to be feasible, implying that it is possible with such an optimized color camera to achieve such a high colorimetric performance that the reproduced colors in an image cannot be distinguished from the original colors in a scene, even in direct comparison.

An inter-laboratory comparison study of image quality of PET scanners using the NEMA NU 2-2001 procedure for assessment of image quality

NASA Astrophysics Data System (ADS)

Bergmann, Helmar; Dobrozemsky, Georg; Minear, Gregory; Nicoletti, Rudolf; Samal, Martin

2005-05-01

An inter-laboratory comparison study was conducted to assess the image quality of PET scanners in Austria. The survey included both dedicated PET scanners (D-PET, n = 8) and coincidence cameras (GC-PET, n = 7). Measurement of image quality was based on the NEMA (National Electrical Manufacturers Association) NU 2-2001 protocol and the IEC (International Electrotechnical Commission) body phantom. The latter contains six fillable spheres ranging in diameter from 37 mm down to 10 mm and a 'lung' insert. The two largest lesions L1-2 simulate cold lesions, the four smaller ones (L3-6) are filled with 18F and activity concentration ratios relative to background of 8:1 and 4:1, respectively. Acquisition and reconstruction in the study employed the participating institutes' standard oncological processing protocol. Calculation of contrast of the spheres was performed with a fully automated procedure. Contrast quality indices (CQIs) reflecting global performance were obtained by summing individual contrast values. Other image quality parameters calculated according to the NEMA protocol were background variability and relative error for correction of attenuation and scatter. Contrast values obtained were 61 ± 16 and 37 ± 14 for L1 (per cent contrast ± SD for D-PET and GC-PET, respectively), 57 ± 16 and 29 ± 16 for L2, 46 ± 10 and 26 ± 6.3 for L3, 37 ± 10 and 15 ± 4.3 for L4, 26 ± 11.5 and 6.1 ± 2.5 for L5, 14 ± 7.1 and 2.6 ± 2.6 for L6, with D-PET systems consistently being superior to GC-PET systems. CQIs permitted ranking of the scanners, also demonstrating a clear distinction between D-PET and GC-PET systems. Background variability was largest for GC-PET systems; the relative error of attenuation and scatter correction was significantly correlated with image quality for D-PET systems only. The study demonstrated considerable differences in image quality not only between GC-PET and D-PET systems but also between individual D-PET systems with possible consequences for clinical interpretation of images and measurement of quantitative indices such as the standardized uptake value. The study provided valuable feedback to the participants as well as baseline data for improving interchangeability of PET images and of quantitative indices between different laboratories.

A novel approach for quantitative harmonization in PET.

PubMed

Namías, M; Bradshaw, T; Menezes, V O; Machado, M A D; Jeraj, R

2018-05-04

Positron emission tomography (PET) imaging allows for measurement of activity concentrations of a given radiotracer in vivo. The quantitative capabilities of PET imaging are particularly important in the context of monitoring response to treatment, where quantitative changes in tracer uptake could be used as a biomarker of treatment response. Reconstruction algorithms and settings have a significant impact on PET quantification. In this work we introduce a novel harmonization methodology requiring only a simple cylindrical phantom and show that it can match the performance of more complex harmonization approaches based on phantoms with spherical inserts. Resolution and noise measurements from cylindrical phantoms are used to simulate the spherical inserts from NEMA image quality phantoms. An optimization algorithm was used to find the optimal smoothing filters for the simulated NEMA phantom images to identify those that best harmonized the PET scanners. Our methodology was tested on seven different PET models from two manufacturers installed at five institutions. Our methodology is able to predict contrast recovery coefficients (CRCs) from NEMA phantoms with errors within  ±5.2% for CRCmax and  ±3.7% for CRCmean (limits of agreement  =  95%). After applying the proposed harmonization protocol, all the CRC values were within the tolerances from EANM. Quantitative harmonization in compliance with the EARL FDG-PET/CT accreditation program is achieved in a simpler way, without the need of NEMA phantoms. This may lead to simplified scanner harmonization workflows more accessible to smaller institutions.

Preliminary studies of PQS PET detector module for dose verification of carbon beam therapy

NASA Astrophysics Data System (ADS)

Kim, H.-I.; An, S. Jung; Lee, C. Y.; Jo, W. J.; Min, E.; Lee, K.; Kim, Y.; Joung, J.; Chung, Y. H.

2014-05-01

PET imaging can be used to verify dose distributions of therapeutic particle beams such as carbon ion beams. The purpose of this study was to develop a PET detector module which was designed for an in-beam PET scanner geometry integrated into a carbon beam therapy system, and to evaluate its feasibility as a monitoring system of patient dose distribution. A C-shaped PET geometry was proposed to avoid blockage of the carbon beam by the detector modules. The proposed PET system consisted of 14 detector modules forming a bore with 30.2 cm inner diameter for brain imaging. Each detector module is composed of a 9 × 9 array of 4.0 mm × 4.0 mm × 20.0 mm LYSO crystal module optically coupled with four 29 mm diameter PMTs using Photomultiplier-quadrant-sharing (PQS) technique. Because the crystal pixel was identified based upon the distribution of scintillation lights of four PMTs, the design of the reflector between crystal elements should be well optimized. The optical design of reflectors was optimized using DETECT2000, a Monte Carlo code for light photon transport. A laser-cut reflector set was developed using the Enhanced Specular Reflector (ESR, 3M Co.) mirror-film with a high reflectance of 98% and a thickness of 0.064 mm. All 81 crystal elements of detector module were identified. Our result demonstrates that the C-shaped PET system is under development and we present the first reconstructed image.

Resolution improvement in positron emission tomography using anatomical Magnetic Resonance Imaging.

PubMed

Chu, Yong; Su, Min-Ying; Mandelkern, Mark; Nalcioglu, Orhan

2006-08-01

An ideal imaging system should provide information with high-sensitivity, high spatial, and temporal resolution. Unfortunately, it is not possible to satisfy all of these desired features in a single modality. In this paper, we discuss methods to improve the spatial resolution in positron emission imaging (PET) using a priori information from Magnetic Resonance Imaging (MRI). Our approach uses an image restoration algorithm based on the maximization of mutual information (MMI), which has found significant success for optimizing multimodal image registration. The MMI criterion is used to estimate the parameters in the Sharpness-Constrained Wiener filter. The generated filter is then applied to restore PET images of a realistic digital brain phantom. The resulting restored images show improved resolution and better signal-to-noise ratio compared to the interpolated PET images. We conclude that a Sharpness-Constrained Wiener filter having parameters optimized from a MMI criterion may be useful for restoring spatial resolution in PET based on a priori information from correlated MRI.

Panorama parking assistant system with improved particle swarm optimization method

NASA Astrophysics Data System (ADS)

Cheng, Ruzhong; Zhao, Yong; Li, Zhichao; Jiang, Weigang; Wang, Xin'an; Xu, Yong

2013-10-01

A panorama parking assistant system (PPAS) for the automotive aftermarket together with a practical improved particle swarm optimization method (IPSO) are proposed in this paper. In the PPAS system, four fisheye cameras are installed in the vehicle with different views, and four channels of video frames captured by the cameras are processed as a 360-deg top-view image around the vehicle. Besides the embedded design of PPAS, the key problem for image distortion correction and mosaicking is the efficiency of parameter optimization in the process of camera calibration. In order to address this problem, an IPSO method is proposed. Compared with other parameter optimization methods, the proposed method allows a certain range of dynamic change for the intrinsic and extrinsic parameters, and can exploit only one reference image to complete all of the optimization; therefore, the efficiency of the whole camera calibration is increased. The PPAS is commercially available, and the IPSO method is a highly practical way to increase the efficiency of the installation and the calibration of PPAS in automobile 4S shops.

SFDT-1 Camera Pointing and Sun-Exposure Analysis and Flight Performance

NASA Technical Reports Server (NTRS)

White, Joseph; Dutta, Soumyo; Striepe, Scott

2015-01-01

The Supersonic Flight Dynamics Test (SFDT) vehicle was developed to advance and test technologies of NASA's Low Density Supersonic Decelerator (LDSD) Technology Demonstration Mission. The first flight test (SFDT-1) occurred on June 28, 2014. In order to optimize the usefulness of the camera data, analysis was performed to optimize parachute visibility in the camera field of view during deployment and inflation and to determine the probability of sun-exposure issues with the cameras given the vehicle heading and launch time. This paper documents the analysis, results and comparison with flight video of SFDT-1.

Evaluation of dynamic row-action maximum likelihood algorithm reconstruction for quantitative 15O brain PET.

PubMed

Ibaraki, Masanobu; Sato, Kaoru; Mizuta, Tetsuro; Kitamura, Keishi; Miura, Shuichi; Sugawara, Shigeki; Shinohara, Yuki; Kinoshita, Toshibumi

2009-09-01

A modified version of row-action maximum likelihood algorithm (RAMLA) using a 'subset-dependent' relaxation parameter for noise suppression, or dynamic RAMLA (DRAMA), has been proposed. The aim of this study was to assess the capability of DRAMA reconstruction for quantitative (15)O brain positron emission tomography (PET). Seventeen healthy volunteers were studied using a 3D PET scanner. The PET study included 3 sequential PET scans for C(15)O, (15)O(2) and H (2) (15) O. First, the number of main iterations (N (it)) in DRAMA was optimized in relation to image convergence and statistical image noise. To estimate the statistical variance of reconstructed images on a pixel-by-pixel basis, a sinogram bootstrap method was applied using list-mode PET data. Once the optimal N (it) was determined, statistical image noise and quantitative parameters, i.e., cerebral blood flow (CBF), cerebral blood volume (CBV), cerebral metabolic rate of oxygen (CMRO(2)) and oxygen extraction fraction (OEF) were compared between DRAMA and conventional FBP. DRAMA images were post-filtered so that their spatial resolutions were matched with FBP images with a 6-mm FWHM Gaussian filter. Based on the count recovery data, N (it) = 3 was determined as an optimal parameter for (15)O PET data. The sinogram bootstrap analysis revealed that DRAMA reconstruction resulted in less statistical noise, especially in a low-activity region compared to FBP. Agreement of quantitative values between FBP and DRAMA was excellent. For DRAMA images, average gray matter values of CBF, CBV, CMRO(2) and OEF were 46.1 +/- 4.5 (mL/100 mL/min), 3.35 +/- 0.40 (mL/100 mL), 3.42 +/- 0.35 (mL/100 mL/min) and 42.1 +/- 3.8 (%), respectively. These values were comparable to corresponding values with FBP images: 46.6 +/- 4.6 (mL/100 mL/min), 3.34 +/- 0.39 (mL/100 mL), 3.48 +/- 0.34 (mL/100 mL/min) and 42.4 +/- 3.8 (%), respectively. DRAMA reconstruction is applicable to quantitative (15)O PET study and is superior to conventional FBP in terms of image quality.

SU-D-201-05: Phantom Study to Determine Optimal PET Reconstruction Parameters for PET/MR Imaging of Y-90 Microspheres Following Radioembolization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Maughan, N; Conti, M; Parikh, P

2015-06-15

Purpose: Imaging Y-90 microspheres with PET/MRI following hepatic radioembolization has the potential for predicting treatment outcome and, in turn, improving patient care. The positron decay branching ratio, however, is very small (32 ppm), yielding images with poor statistics even when therapy doses are used. Our purpose is to find PET reconstruction parameters that maximize the PET recovery coefficients and minimize noise. Methods: An initial 7.5 GBq of Y-90 chloride solution was used to fill an ACR phantom for measurements with a PET/MRI scanner (Siemens Biograph mMR). Four hot cylinders and a warm background activity volume of the phantom were filledmore » with a 10:1 ratio. Phantom attenuation maps were derived from scaled CT images of the phantom and included the MR phased array coil. The phantom was imaged at six time points between 7.5–1.0 GBq total activity over a period of eight days. PET images were reconstructed via OP-OSEM with 21 subsets and varying iteration number (1–5), post-reconstruction filter size (5–10 mm), and either absolute or relative scatter correction. Recovery coefficients, SNR, and noise were measured as well as total activity in the phantom. Results: For the 120 different reconstructions, recovery coefficients ranged from 0.1–0.6 and improved with increasing iteration number and reduced post-reconstruction filter size. SNR, however, improved substantially with lower iteration numbers and larger post-reconstruction filters. From the phantom data, we found that performing 2 iterations, 21 subsets, and applying a 5 mm Gaussian post-reconstruction filter provided optimal recovery coefficients at a moderate noise level for a wide range of activity levels. Conclusion: The choice of reconstruction parameters for Y-90 PET images greatly influences both the accuracy of measurements and image quality. We have found reconstruction parameters that provide optimal recovery coefficients with minimized noise. Future work will include the effects of the body matrix coil and off-center measurements.« less

Photography in Dermatologic Surgery: Selection of an Appropriate Camera Type for a Particular Clinical Application.

PubMed

Chen, Brian R; Poon, Emily; Alam, Murad

2017-08-01

Photographs are an essential tool for the documentation and sharing of findings in dermatologic surgery, and various camera types are available. To evaluate the currently available camera types in view of the special functional needs of procedural dermatologists. Mobile phone, point and shoot, digital single-lens reflex (DSLR), digital medium format, and 3-dimensional cameras were compared in terms of their usefulness for dermatologic surgeons. For each camera type, the image quality, as well as the other practical benefits and limitations, were evaluated with reference to a set of ideal camera characteristics. Based on these assessments, recommendations were made regarding the specific clinical circumstances in which each camera type would likely be most useful. Mobile photography may be adequate when ease of use, availability, and accessibility are prioritized. Point and shoot cameras and DSLR cameras provide sufficient resolution for a range of clinical circumstances, while providing the added benefit of portability. Digital medium format cameras offer the highest image quality, with accurate color rendition and greater color depth. Three-dimensional imaging may be optimal for the definition of skin contour. The selection of an optimal camera depends on the context in which it will be used.

New techniques for positron emission tomography in the study of human neurological disorders

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuhl, D.E.

1992-07-01

The general goals of the physics and kinetic modeling projects are to: (1) improve the quantitative information extractable from PET images, and (2) develop, implement and optimize tracer kinetic models for new PET neurotransmitter/receptor ligands aided by computer simulations. Work towards improving PET quantification has included projects evaluating: (1) iterative reconstruction algorithms using supplemental boundary information, (2) automated registration of dynamic PET emission and transmission data using sinogram edge detection, and (3) automated registration of multiple subjects to a common coordinate system, including the use of non-linear warping methods. Simulation routines have been developed providing more accurate representation of datamore » generated from neurotransmitter/receptor studies. Routines consider data generated from complex compartmental models, high or low specific activity administrations, non-specific binding, pre- or post-injection of cold or competing ligands, temporal resolution of the data, and radiolabeled metabolites. Computer simulations and human PET studies have been performed to optimize kinetic models for four new neurotransmitter/receptor ligands, [{sup 11}C]TRB (muscarinic), [{sup 11}C]flumazenil (benzodiazepine), [{sup 18}F]GBR12909, (dopamine), and [{sup 11}C]NMPB (muscarinic).« less

New techniques for positron emission tomography in the study of human neurological disorders

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuhl, D.E.

1992-01-01

The general goals of the physics and kinetic modeling projects are to: (1) improve the quantitative information extractable from PET images, and (2) develop, implement and optimize tracer kinetic models for new PET neurotransmitter/receptor ligands aided by computer simulations. Work towards improving PET quantification has included projects evaluating: (1) iterative reconstruction algorithms using supplemental boundary information, (2) automated registration of dynamic PET emission and transmission data using sinogram edge detection, and (3) automated registration of multiple subjects to a common coordinate system, including the use of non-linear warping methods. Simulation routines have been developed providing more accurate representation of datamore » generated from neurotransmitter/receptor studies. Routines consider data generated from complex compartmental models, high or low specific activity administrations, non-specific binding, pre- or post-injection of cold or competing ligands, temporal resolution of the data, and radiolabeled metabolites. Computer simulations and human PET studies have been performed to optimize kinetic models for four new neurotransmitter/receptor ligands, ({sup 11}C)TRB (muscarinic), ({sup 11}C)flumazenil (benzodiazepine), ({sup 18}F)GBR12909, (dopamine), and ({sup 11}C)NMPB (muscarinic).« less

Optimization of oncological {sup 18}F-FDG PET/CT imaging based on a multiparameter analysis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Menezes, Vinicius O., E-mail: vinicius@radtec.com.br; Machado, Marcos A. D.; Queiroz, Cleiton C.

2016-02-15

Purpose: This paper describes a method to achieve consistent clinical image quality in {sup 18}F-FDG scans accounting for patient habitus, dose regimen, image acquisition, and processing techniques. Methods: Oncological PET/CT scan data for 58 subjects were evaluated retrospectively to derive analytical curves that predict image quality. Patient noise equivalent count rate and coefficient of variation (CV) were used as metrics in their analysis. Optimized acquisition protocols were identified and prospectively applied to 179 subjects. Results: The adoption of different schemes for three body mass ranges (<60 kg, 60–90 kg, >90 kg) allows improved image quality with both point spread functionmore » and ordered-subsets expectation maximization-3D reconstruction methods. The application of this methodology showed that CV improved significantly (p < 0.0001) in clinical practice. Conclusions: Consistent oncological PET/CT image quality on a high-performance scanner was achieved from an analysis of the relations existing between dose regimen, patient habitus, acquisition, and processing techniques. The proposed methodology may be used by PET/CT centers to develop protocols to standardize PET/CT imaging procedures and achieve better patient management and cost-effective operations.« less

Derivation of the scan time requirement for maintaining a consistent PET image quality

NASA Astrophysics Data System (ADS)

Kim, Jin Su; Lee, Jae Sung; Kim, Seok-Ki

2015-05-01

Objectives: the image quality of PET for larger patients is relatively poor, even though the injection dose is optimized considering the NECR characteristics of the PET scanner. This poor image quality is due to the lower level of maximum NECR that can be achieved in these large patients. The aim of this study was to optimize the PET scan time to obtain a consistent PET image quality regardless of the body size, based on the relationship between the patient specific NECR (pNECR) and body weight. Methods: eighty patients (M/F=53/27, body weight: 059 ± 1 kg) underwent whole-body FDG PET scans using a Philips GEMINI GS PET/CT scanner after an injection of 0.14 mCi/kg FDG. The relationship between the scatter fraction (SF) and body weight was determined by repeated Monte Carlo simulations using a NEMA scatter phantom, the size of which varied according to the relationship between the abdominal circumference and body weight. Using this information, the pNECR was calculated from the prompt and delayed PET sinograms to obtain the prediction equation of NECR vs. body weight. The time scaling factor (FTS) for the scan duration was finally derived to make PET images with equivalent SNR levels. Results: the SF and NECR had the following nonlinear relationships with the body weight: SF=0.15 ṡ body weight0.3 and NECR = 421.36 (body weight)-0.84. The equation derived for FTS was 0.01ṡ body weight + 0.2, which means that, for example, a 120-kg person should be scanned 1.8 times longer than a 70 kg person, or the scan time for a 40-kg person can be reduced by 30%. Conclusion: the equation of the relative time demand derived in this study will be useful for maintaining consistent PET image quality in clinics.

Artifacts in Digital Coincidence Timing

PubMed Central

Moses, W. W.; Peng, Q.

2014-01-01

Digital methods are becoming increasingly popular for measuring time differences, and are the de facto standard in PET cameras. These methods usually include a master system clock and a (digital) arrival time estimate for each detector that is obtained by comparing the detector output signal to some reference portion of this clock (such as the rising edge). Time differences between detector signals are then obtained by subtracting the digitized estimates from a detector pair. A number of different methods can be used to generate the digitized arrival time of the detector output, such as sending a discriminator output into a time to digital converter (TDC) or digitizing the waveform and applying a more sophisticated algorithm to extract a timing estimator. All measurement methods are subject to error, and one generally wants to minimize these errors and so optimize the timing resolution. A common method for optimizing timing methods is to measure the coincidence timing resolution between two timing signals whose time difference should be constant (such as detecting gammas from positron annihilation) and selecting the method that minimizes the width of the distribution (i.e., the timing resolution). Unfortunately, a common form of error (a nonlinear transfer function) leads to artifacts that artificially narrow this resolution, which can lead to erroneous selection of the “optimal” method. The purpose of this note is to demonstrate the origin of this artifact and suggest that caution should be used when optimizing time digitization systems solely on timing resolution minimization. PMID:25321885

Surveillance of a 2D Plane Area with 3D Deployed Cameras

PubMed Central

Fu, Yi-Ge; Zhou, Jie; Deng, Lei

2014-01-01

As the use of camera networks has expanded, camera placement to satisfy some quality assurance parameters (such as a good coverage ratio, an acceptable resolution constraints, an acceptable cost as low as possible, etc.) has become an important problem. The discrete camera deployment problem is NP-hard and many heuristic methods have been proposed to solve it, most of which make very simple assumptions. In this paper, we propose a probability inspired binary Particle Swarm Optimization (PI-BPSO) algorithm to solve a homogeneous camera network placement problem. We model the problem under some more realistic assumptions: (1) deploy the cameras in the 3D space while the surveillance area is restricted to a 2D ground plane; (2) deploy the minimal number of cameras to get a maximum visual coverage under more constraints, such as field of view (FOV) of the cameras and the minimum resolution constraints. We can simultaneously optimize the number and the configuration of the cameras through the introduction of a regulation item in the cost function. The simulation results showed the effectiveness of the proposed PI-BPSO algorithm. PMID:24469353

Improved UTE-based attenuation correction for cranial PET-MR using dynamic magnetic field monitoring

DOE Office of Scientific and Technical Information (OSTI.GOV)

Aitken, A. P.; Giese, D.; Tsoumpas, C.

2014-01-15

Purpose: Ultrashort echo time (UTE) MRI has been proposed as a way to produce segmented attenuation maps for PET, as it provides contrast between bone, air, and soft tissue. However, UTE sequences require samples to be acquired during rapidly changing gradient fields, which makes the resulting images prone to eddy current artifacts. In this work it is demonstrated that this can lead to misclassification of tissues in segmented attenuation maps (AC maps) and that these effects can be corrected for by measuring the true k-space trajectories using a magnetic field camera. Methods: The k-space trajectories during a dual echo UTEmore » sequence were measured using a dynamic magnetic field camera. UTE images were reconstructed using nominal trajectories and again using the measured trajectories. A numerical phantom was used to demonstrate the effect of reconstructing with incorrect trajectories. Images of an ovine leg phantom were reconstructed and segmented and the resulting attenuation maps were compared to a segmented map derived from a CT scan of the same phantom, using the Dice similarity measure. The feasibility of the proposed method was demonstrated inin vivo cranial imaging in five healthy volunteers. Simulated PET data were generated for one volunteer to show the impact of misclassifications on the PET reconstruction. Results: Images of the numerical phantom exhibited blurring and edge artifacts on the bone–tissue and air–tissue interfaces when nominal k-space trajectories were used, leading to misclassification of soft tissue as bone and misclassification of bone as air. Images of the tissue phantom and thein vivo cranial images exhibited the same artifacts. The artifacts were greatly reduced when the measured trajectories were used. For the tissue phantom, the Dice coefficient for bone in MR relative to CT was 0.616 using the nominal trajectories and 0.814 using the measured trajectories. The Dice coefficients for soft tissue were 0.933 and 0.934 for the nominal and measured cases, respectively. For air the corresponding figures were 0.991 and 0.993. Compared to an unattenuated reference image, the mean error in simulated PET uptake in the brain was 9.16% when AC maps derived from nominal trajectories was used, with errors in the SUV{sub max} for simulated lesions in the range of 7.17%–12.19%. Corresponding figures when AC maps derived from measured trajectories were used were 0.34% (mean error) and −0.21% to +1.81% (lesions). Conclusions: Eddy current artifacts in UTE imaging can be corrected for by measuring the true k-space trajectories during a calibration scan and using them in subsequent image reconstructions. This improves the accuracy of segmented PET attenuation maps derived from UTE sequences and subsequent PET reconstruction.« less

A front-end readout Detector Board for the OpenPET electronics system

NASA Astrophysics Data System (ADS)

Choong, W.-S.; Abu-Nimeh, F.; Moses, W. W.; Peng, Q.; Vu, C. Q.; Wu, J.-Y.

2015-08-01

We present a 16-channel front-end readout board for the OpenPET electronics system. A major task in developing a nuclear medical imaging system, such as a positron emission computed tomograph (PET) or a single-photon emission computed tomograph (SPECT), is the electronics system. While there are a wide variety of detector and camera design concepts, the relatively simple nature of the acquired data allows for a common set of electronics requirements that can be met by a flexible, scalable, and high-performance OpenPET electronics system. The analog signals from the different types of detectors used in medical imaging share similar characteristics, which allows for a common analog signal processing. The OpenPET electronics processes the analog signals with Detector Boards. Here we report on the development of a 16-channel Detector Board. Each signal is digitized by a continuously sampled analog-to-digital converter (ADC), which is processed by a field programmable gate array (FPGA) to extract pulse height information. A leading edge discriminator creates a timing edge that is ``time stamped'' by a time-to-digital converter (TDC) implemented inside the FPGA . This digital information from each channel is sent to an FPGA that services 16 analog channels, and then information from multiple channels is processed by this FPGA to perform logic for crystal lookup, DOI calculation, calibration, etc.

A front-end readout Detector Board for the OpenPET electronics system

DOE PAGES

Choong, W. -S.; Abu-Nimeh, F.; Moses, W. W.; ...

2015-08-12

Here, we present a 16-channel front-end readout board for the OpenPET electronics system. A major task in developing a nuclear medical imaging system, such as a positron emission computed tomograph (PET) or a single-photon emission computed tomograph (SPECT), is the electronics system. While there are a wide variety of detector and camera design concepts, the relatively simple nature of the acquired data allows for a common set of electronics requirements that can be met by a flexible, scalable, and high-performance OpenPET electronics system. The analog signals from the different types of detectors used in medical imaging share similar characteristics, whichmore » allows for a common analog signal processing. The OpenPET electronics processes the analog signals with Detector Boards. Here we report on the development of a 16-channel Detector Board. Each signal is digitized by a continuously sampled analog-to-digital converter (ADC), which is processed by a field programmable gate array (FPGA) to extract pulse height information. A leading edge discriminator creates a timing edge that is "time stamped" by a time-to-digital converter (TDC) implemented inside the FPGA. In conclusion, this digital information from each channel is sent to an FPGA that services 16 analog channels, and then information from multiple channels is processed by this FPGA to perform logic for crystal lookup, DOI calculation, calibration, etc.« less

Comparison of parameters of modern cooled and uncooled thermal cameras

NASA Astrophysics Data System (ADS)

Bareła, Jarosław; Kastek, Mariusz; Firmanty, Krzysztof; Krupiński, Michał

2017-10-01

During the design of a system employing thermal cameras one always faces a problem of choosing the camera types best suited for the task. In many cases such a choice is far from optimal one, and there are several reasons for that. System designers often favor tried and tested solution they are used to. They do not follow the latest developments in the field of infrared technology and sometimes their choices are based on prejudice and not on facts. The paper presents the results of measurements of basic parameters of MWIR and LWIR thermal cameras, carried out in a specialized testing laboratory. The measured parameters are decisive in terms of image quality generated by thermal cameras. All measurements were conducted according to current procedures and standards. However the camera settings were not optimized for a specific test conditions or parameter measurements. Instead the real settings used in normal camera operations were applied to obtain realistic camera performance figures. For example there were significant differences between measured values of noise parameters and catalogue data provided by manufacturers, due to the application of edge detection filters to increase detection and recognition ranges. The purpose of this paper is to provide help in choosing the optimal thermal camera for particular application, answering the question whether to opt for cheaper microbolometer device or apply slightly better (in terms of specifications) yet more expensive cooled unit. Measurements and analysis were performed by qualified personnel with several dozen years of experience in both designing and testing of thermal camera systems with both cooled and uncooled focal plane arrays. Cameras of similar array sizes and optics were compared, and for each tested group the best performing devices were selected.

Differentiation between Malignant and Benign Solitary Lesions in the Liver with 18FDG PET/CT: Accuracy of Age-related Diagnostic Standard

PubMed Central

Xia, Qian; Feng, Yuanbo; Wu, Cheng; Huang, Gang; Liu, Jianjun; Chen, Tao; Sun, Xiaoguang; Song, Shaoli; Tong, Linjun; Ni, Yicheng

2015-01-01

Objective: This study was to determine the reliability of age-stratified diagnostic index in differential diagnosis of malignant and benign solitary lesions in the liver using fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (18FDG PET/CT). Methods: The enrolled 272 patients with solitary lesions in the liver were divided into three age groups, younger group (under 50 years), middle-aged group (50-69 years), and elderly group (70 years and above). Patients' ages were compared, and the optimal cut-offs of the standard uptake value (SUV) ratio (tumor-to-non-tumor ratio of the SUV), as well as areas under the curves (AUC), were evaluated in terms of malignant and benign lesions in each age group by using receiver operating characteristic (ROC) analysis. Based on optimal cut-offs, the sensitivity, specificity, accuracy were calculated, and the diagnostic accordance rate was compared between each age group and all patients, supported by 18FDG PET/CT imaging data. Results: There was a significant age difference between the malignant and benign groups (t=3.905 p=0.0001). ROC analysis showed that the optimal cut-off value in all patients, younger group, middle-aged group and elderly group was 1.25, 1.17, 1.45 and 1.25 for SUVratio, and 0.856, 0.962, 0.650, 0.973 for AUC. The chi-square test proved that diagnostic accordance rate of 18FDG PET/CT in younger group and elderly group were superior to that in all patients (χ2=13.352, P=0.0003) and (χ2=8.494, P=0.0036). Conversely, overall diagnostic accordance rate in all patient group was higher than that in middle-aged group (χ2=9.057, P=0.0026). Representative 18FDG PET/CT imaging findings are demonstrated. Conclusion: This study indicates that diagnostic optimal cut-offs of SUVratio of liver solitary lesions of 18FDG PET/CT were different in each age group. In addition, the diagnostic performance of SUVratio was better in younger and elderly groups than that in all patients, and was poorer in middle-aged group than that in all patients. Therefore, age difference appears to be one of the important factors for discriminating malignant liver lesions from benign ones using 18 FDG PET/CT. PMID:25553087

Empirical Study on Designing of Gaze Tracking Camera Based on the Information of User's Head Movement.

PubMed

Pan, Weiyuan; Jung, Dongwook; Yoon, Hyo Sik; Lee, Dong Eun; Naqvi, Rizwan Ali; Lee, Kwan Woo; Park, Kang Ryoung

2016-08-31

Gaze tracking is the technology that identifies a region in space that a user is looking at. Most previous non-wearable gaze tracking systems use a near-infrared (NIR) light camera with an NIR illuminator. Based on the kind of camera lens used, the viewing angle and depth-of-field (DOF) of a gaze tracking camera can be different, which affects the performance of the gaze tracking system. Nevertheless, to our best knowledge, most previous researches implemented gaze tracking cameras without ground truth information for determining the optimal viewing angle and DOF of the camera lens. Eye-tracker manufacturers might also use ground truth information, but they do not provide this in public. Therefore, researchers and developers of gaze tracking systems cannot refer to such information for implementing gaze tracking system. We address this problem providing an empirical study in which we design an optimal gaze tracking camera based on experimental measurements of the amount and velocity of user's head movements. Based on our results and analyses, researchers and developers might be able to more easily implement an optimal gaze tracking system. Experimental results show that our gaze tracking system shows high performance in terms of accuracy, user convenience and interest.

Empirical Study on Designing of Gaze Tracking Camera Based on the Information of User’s Head Movement

PubMed Central

Pan, Weiyuan; Jung, Dongwook; Yoon, Hyo Sik; Lee, Dong Eun; Naqvi, Rizwan Ali; Lee, Kwan Woo; Park, Kang Ryoung

2016-01-01

Gaze tracking is the technology that identifies a region in space that a user is looking at. Most previous non-wearable gaze tracking systems use a near-infrared (NIR) light camera with an NIR illuminator. Based on the kind of camera lens used, the viewing angle and depth-of-field (DOF) of a gaze tracking camera can be different, which affects the performance of the gaze tracking system. Nevertheless, to our best knowledge, most previous researches implemented gaze tracking cameras without ground truth information for determining the optimal viewing angle and DOF of the camera lens. Eye-tracker manufacturers might also use ground truth information, but they do not provide this in public. Therefore, researchers and developers of gaze tracking systems cannot refer to such information for implementing gaze tracking system. We address this problem providing an empirical study in which we design an optimal gaze tracking camera based on experimental measurements of the amount and velocity of user’s head movements. Based on our results and analyses, researchers and developers might be able to more easily implement an optimal gaze tracking system. Experimental results show that our gaze tracking system shows high performance in terms of accuracy, user convenience and interest. PMID:27589768

PET-Tool: a software suite for comprehensive processing and managing of Paired-End diTag (PET) sequence data.

PubMed

Chiu, Kuo Ping; Wong, Chee-Hong; Chen, Qiongyu; Ariyaratne, Pramila; Ooi, Hong Sain; Wei, Chia-Lin; Sung, Wing-Kin Ken; Ruan, Yijun

2006-08-25

We recently developed the Paired End diTag (PET) strategy for efficient characterization of mammalian transcriptomes and genomes. The paired end nature of short PET sequences derived from long DNA fragments raised a new set of bioinformatics challenges, including how to extract PETs from raw sequence reads, and correctly yet efficiently map PETs to reference genome sequences. To accommodate and streamline data analysis of the large volume PET sequences generated from each PET experiment, an automated PET data process pipeline is desirable. We designed an integrated computation program package, PET-Tool, to automatically process PET sequences and map them to the genome sequences. The Tool was implemented as a web-based application composed of four modules: the Extractor module for PET extraction; the Examiner module for analytic evaluation of PET sequence quality; the Mapper module for locating PET sequences in the genome sequences; and the Project Manager module for data organization. The performance of PET-Tool was evaluated through the analyses of 2.7 million PET sequences. It was demonstrated that PET-Tool is accurate and efficient in extracting PET sequences and removing artifacts from large volume dataset. Using optimized mapping criteria, over 70% of quality PET sequences were mapped specifically to the genome sequences. With a 2.4 GHz LINUX machine, it takes approximately six hours to process one million PETs from extraction to mapping. The speed, accuracy, and comprehensiveness have proved that PET-Tool is an important and useful component in PET experiments, and can be extended to accommodate other related analyses of paired-end sequences. The Tool also provides user-friendly functions for data quality check and system for multi-layer data management.

Current Methods to Define Metabolic Tumor Volume in Positron Emission Tomography: Which One is Better?

PubMed

Im, Hyung-Jun; Bradshaw, Tyler; Solaiyappan, Meiyappan; Cho, Steve Y

2018-02-01

Numerous methods to segment tumors using 18 F-fluorodeoxyglucose positron emission tomography (FDG PET) have been introduced. Metabolic tumor volume (MTV) refers to the metabolically active volume of the tumor segmented using FDG PET, and has been shown to be useful in predicting patient outcome and in assessing treatment response. Also, tumor segmentation using FDG PET has useful applications in radiotherapy treatment planning. Despite extensive research on MTV showing promising results, MTV is not used in standard clinical practice yet, mainly because there is no consensus on the optimal method to segment tumors in FDG PET images. In this review, we discuss currently available methods to measure MTV using FDG PET, and assess the advantages and disadvantages of the methods.

Commercial and PET radioisotope manufacturing with a medical cyclotron

NASA Astrophysics Data System (ADS)

Boothe, T. E.; McLeod, T. F.; Plitnikas, M.; Kinney, D.; Tavano, E.; Feijoo, Y.; Smith, P.; Szelecsényi, F.

1993-06-01

Mount Sinai has extensive experience in producing radionuclides for commercial sales and for incorporation into radiopharmaceuticals, including PET. Currently, an attempt is being made to supply radiochemicals to radiopharmaceutical manufacturers outside the hospital, to prepare radiopharmaceuticals for in-house use, and to prepare PET radiopharmaceuticals, such as 2-[F-18] FDG, for outside sales. This use for both commercial and PET manufacturing is atypical for a hospital-based cyclotron. To accomplish PET radiopharmaceutical sales, the hospital operates a nuclear pharmacy. A review of operational details for the past several years shows a continuing dependence on commercial sales which is reflected in research and developmental aspects and in staffing. Developmental efforts have centered primarily on radionuclide production, target development, and radiochemical processing optimization.

A philosophy for CNS radiotracer design

DOE PAGES

Van de Bittner, Genevieve C.; Ricq, Emily L.; Hooker, Jacob M.

2014-10-01

Decades after its discovery, positron emission tomography (PET) remains the premier tool for imaging neurochemistry in living humans. Technological improvements in radiolabeling methods, camera design, and image analysis have kept PET in the forefront. In addition, the use of PET imaging has expanded because researchers have developed new radiotracers that visualize receptors, transporters, enzymes, and other molecular targets within the human brain. However, of the thousands of proteins in the central nervous system (CNS), researchers have successfully imaged fewer than 40 human proteins. To address the critical need for new radiotracers, this Account expounds on the decisions, strategies, and pitfallsmore » of CNS radiotracer development based on our current experience in this area. We discuss the five key components of radiotracer development for human imaging: choosing a biomedical question, selection of a biological target, design of the radiotracer chemical structure, evaluation of candidate radiotracers, and analysis of preclinical imaging. It is particularly important to analyze the market of scientists or companies who might use a new radiotracer and carefully select a relevant biomedical question(s) for that audience. In the selection of a specific biological target, we emphasize how target localization and identity can constrain this process and discuss the optimal target density and affinity ratios needed for binding-based radiotracers. In addition, we discuss various PET test–retest variability requirements for monitoring changes in density, occupancy, or functionality for new radiotracers. In the synthesis of new radiotracer structures, high-throughput, modular syntheses have proved valuable, and these processes provide compounds with sites for late-stage radioisotope installation. As a result, researchers can manage the time constraints associated with the limited half-lives of isotopes. In order to evaluate brain uptake, a number of methods are available to predict bioavailability, blood–brain barrier (BBB) permeability, and the associated issues of nonspecific binding and metabolic stability. To evaluate the synthesized chemical library, researchers need to consider high-throughput affinity assays, the analysis of specific binding, and the importance of fast binding kinetics. Lastly, we describe how we initially assess preclinical radiotracer imaging, using brain uptake, specific binding, and preliminary kinetic analysis to identify promising radiotracers that may be useful for human brain imaging. Although we discuss these five design components separately and linearly in this Account, in practice we develop new PET-based radiotracers using these design components nonlinearly and iteratively to develop new compounds in the most efficient way possible.« less

A Philosophy for CNS Radiotracer Design

PubMed Central

2015-01-01

Conspectus Decades after its discovery, positron emission tomography (PET) remains the premier tool for imaging neurochemistry in living humans. Technological improvements in radiolabeling methods, camera design, and image analysis have kept PET in the forefront. In addition, the use of PET imaging has expanded because researchers have developed new radiotracers that visualize receptors, transporters, enzymes, and other molecular targets within the human brain. However, of the thousands of proteins in the central nervous system (CNS), researchers have successfully imaged fewer than 40 human proteins. To address the critical need for new radiotracers, this Account expounds on the decisions, strategies, and pitfalls of CNS radiotracer development based on our current experience in this area. We discuss the five key components of radiotracer development for human imaging: choosing a biomedical question, selection of a biological target, design of the radiotracer chemical structure, evaluation of candidate radiotracers, and analysis of preclinical imaging. It is particularly important to analyze the market of scientists or companies who might use a new radiotracer and carefully select a relevant biomedical question(s) for that audience. In the selection of a specific biological target, we emphasize how target localization and identity can constrain this process and discuss the optimal target density and affinity ratios needed for binding-based radiotracers. In addition, we discuss various PET test–retest variability requirements for monitoring changes in density, occupancy, or functionality for new radiotracers. In the synthesis of new radiotracer structures, high-throughput, modular syntheses have proved valuable, and these processes provide compounds with sites for late-stage radioisotope installation. As a result, researchers can manage the time constraints associated with the limited half-lives of isotopes. In order to evaluate brain uptake, a number of methods are available to predict bioavailability, blood–brain barrier (BBB) permeability, and the associated issues of nonspecific binding and metabolic stability. To evaluate the synthesized chemical library, researchers need to consider high-throughput affinity assays, the analysis of specific binding, and the importance of fast binding kinetics. Finally, we describe how we initially assess preclinical radiotracer imaging, using brain uptake, specific binding, and preliminary kinetic analysis to identify promising radiotracers that may be useful for human brain imaging. Although we discuss these five design components separately and linearly in this Account, in practice we develop new PET-based radiotracers using these design components nonlinearly and iteratively to develop new compounds in the most efficient way possible. PMID:25272291

Data-driven optimal binning for respiratory motion management in PET.

PubMed

Kesner, Adam L; Meier, Joseph G; Burckhardt, Darrell D; Schwartz, Jazmin; Lynch, David A

2018-01-01

Respiratory gating has been used in PET imaging to reduce the amount of image blurring caused by patient motion. Optimal binning is an approach for using the motion-characterized data by binning it into a single, easy to understand/use, optimal bin. To date, optimal binning protocols have utilized externally driven motion characterization strategies that have been tuned with population-derived assumptions and parameters. In this work, we are proposing a new strategy with which to characterize motion directly from a patient's gated scan, and use that signal to create a patient/instance-specific optimal bin image. Two hundred and nineteen phase-gated FDG PET scans, acquired using data-driven gating as described previously, were used as the input for this study. For each scan, a phase-amplitude motion characterization was generated and normalized using principle component analysis. A patient-specific "optimal bin" window was derived using this characterization, via methods that mirror traditional optimal window binning strategies. The resulting optimal bin images were validated by correlating quantitative and qualitative measurements in the population of PET scans. In 53% (n = 115) of the image population, the optimal bin was determined to include 100% of the image statistics. In the remaining images, the optimal binning windows averaged 60% of the statistics and ranged between 20% and 90%. Tuning the algorithm, through a single acceptance window parameter, allowed for adjustments of the algorithm's performance in the population toward conservation of motion or reduced noise-enabling users to incorporate their definition of optimal. In the population of images that were deemed appropriate for segregation, average lesion SUV max were 7.9, 8.5, and 9.0 for nongated images, optimal bin, and gated images, respectively. The Pearson correlation of FWHM measurements between optimal bin images and gated images were better than with nongated images, 0.89 and 0.85, respectively. Generally, optimal bin images had better resolution than the nongated images and better noise characteristics than the gated images. We extended the concept of optimal binning to a data-driven form, updating a traditionally one-size-fits-all approach to a conformal one that supports adaptive imaging. This automated strategy was implemented easily within a large population and encapsulated motion information in an easy to use 3D image. Its simplicity and practicality may make this, or similar approaches ideal for use in clinical settings. © 2017 American Association of Physicists in Medicine.

Intraprocedural yttrium-90 positron emission tomography/CT for treatment optimization of yttrium-90 radioembolization.

PubMed

Bourgeois, Austin C; Chang, Ted T; Bradley, Yong C; Acuff, Shelley N; Pasciak, Alexander S

2014-02-01

Radioembolization with yttrium-90 ((90)Y) microspheres relies on delivery of appropriate treatment activity to ensure patient safety and optimize treatment efficacy. We report a case in which (90)Y positron emission tomography (PET)/computed tomography (CT) was performed to optimize treatment planning during a same-day, three-part treatment session. This treatment consisted of (i) an initial (90)Y infusion with a dosage determined using an empiric treatment planning model, (ii) quantitative (90)Y PET/CT imaging, and (iii) a secondary infusion with treatment planning based on quantitative imaging data with the goal of delivering a specific total tumor absorbed dose. © 2014 SIR Published by SIR All rights reserved.

NEMA image quality phantom measurements and attenuation correction in integrated PET/MR hybrid imaging.

PubMed

Ziegler, Susanne; Jakoby, Bjoern W; Braun, Harald; Paulus, Daniel H; Quick, Harald H

2015-12-01

In integrated PET/MR hybrid imaging the evaluation of PET performance characteristics according to the NEMA standard NU 2-2007 is challenging because of incomplete MR-based attenuation correction (AC) for phantom imaging. In this study, a strategy for CT-based AC of the NEMA image quality (IQ) phantom is assessed. The method is systematically evaluated in NEMA IQ phantom measurements on an integrated PET/MR system. NEMA IQ measurements were performed on the integrated 3.0 Tesla PET/MR hybrid system (Biograph mMR, Siemens Healthcare). AC of the NEMA IQ phantom was realized by an MR-based and by a CT-based method. The suggested CT-based AC uses a template μ-map of the NEMA IQ phantom and a phantom holder for exact repositioning of the phantom on the systems patient table. The PET image quality parameters contrast recovery, background variability, and signal-to-noise ratio (SNR) were determined and compared for both phantom AC methods. Reconstruction parameters of an iterative 3D OP-OSEM reconstruction were optimized for highest lesion SNR in NEMA IQ phantom imaging. Using a CT-based NEMA IQ phantom μ-map on the PET/MR system is straightforward and allowed performing accurate NEMA IQ measurements on the hybrid system. MR-based AC was determined to be insufficient for PET quantification in the tested NEMA IQ phantom because only photon attenuation caused by the MR-visible phantom filling but not the phantom housing is considered. Using the suggested CT-based AC, the highest SNR in this phantom experiment for small lesions (<= 13 mm) was obtained with 3 iterations, 21 subsets and 4 mm Gaussian filtering. This study suggests CT-based AC for the NEMA IQ phantom when performing PET NEMA IQ measurements on an integrated PET/MR hybrid system. The superiority of CT-based AC for this phantom is demonstrated by comparison to measurements using MR-based AC. Furthermore, optimized PET image reconstruction parameters are provided for the highest lesion SNR in NEMA IQ phantom measurements.

TandemPET-A High Resolution, Small Animal, Virtual Pinhole-Based PET Scanner: Initial Design Study

NASA Astrophysics Data System (ADS)

Raylman, Raymond R.; Stolin, Alexander V.; Martone, Peter F.; Smith, Mark F.

2016-02-01

Mice are the perhaps the most common species of rodents used in biomedical research, but many of the current generation of small animal PET scanners are non-optimal for imaging these small rodents due to their relatively low resolution. Consequently, a number of researchers have investigated the development of high-resolution scanners to address this need. In this investigation, the design of a novel, high-resolution system based on the dual-detector, virtual-pinhole PET concept was explored via Monte Carlo simulations. Specifically, this system, called TandemPET, consists of a 5 cm × 5 cm high-resolution detector made-up of a 90 × 90 array of 0.5 mm × 0.5 × 10 mm (pitch = 0.55 mm) LYSO detector elements in coincidence with a lower resolution detector consisting of a 68 × 68 array of 1.5 mm × 1.5 mm × 10 mm LYSO detector elements (total size = 10.5 cm × 10.5 cm). Analyses indicated that TandemPET's optimal geometry is to position the high-resolution detector 3 cm from the center-of-rotation, with the lower resolution detector positioned 9 cm from center. Measurements using modified NEMA NU4-2008-based protocols revealed that the spatial resolution of the system is 0.5 mm FWHM, after correction of positron range effects. Peak sensitivity is 2.1%, which is comparable to current small animal PET scanners. Images from a digital mouse brain phantom demonstrated the potential of the system for identifying important neurological structures.

Adjustable control station with movable monitors and cameras for viewing systems in robotics and teleoperations

NASA Technical Reports Server (NTRS)

Diner, Daniel B. (Inventor)

1994-01-01

Real-time video presentations are provided in the field of operator-supervised automation and teleoperation, particularly in control stations having movable cameras for optimal viewing of a region of interest in robotics and teleoperations for performing different types of tasks. Movable monitors to match the corresponding camera orientations (pan, tilt, and roll) are provided in order to match the coordinate systems of all the monitors to the operator internal coordinate system. Automated control of the arrangement of cameras and monitors, and of the configuration of system parameters, is provided for optimal viewing and performance of each type of task for each operator since operators have different individual characteristics. The optimal viewing arrangement and system parameter configuration is determined and stored for each operator in performing each of many types of tasks in order to aid the automation of setting up optimal arrangements and configurations for successive tasks in real time. Factors in determining what is optimal include the operator's ability to use hand-controllers for each type of task. Robot joint locations, forces and torques are used, as well as the operator's identity, to identify the current type of task being performed in order to call up a stored optimal viewing arrangement and system parameter configuration.

Protein crystallography and site-direct mutagenesis analysis of the poly(ethylene terephthalate) hydrolase PETase from Ideonella sakaiensis.

PubMed

Liu, Bing; He, Lihui; Wang, Liping; Li, Tao; Li, Changcheng; Liu, Huayi; Luo, Yunzi; Bao, Rui

2018-03-30

Compared with traditional recycle strategies, biodegradation provides a sustainable solution for poly (ethylene terephthalate) (PET) wastes disposal. PETase, a newly identified enzyme from Ideonella sakaiensis, has high efficiency and specificity towards PET, which provides a prominent prospect on PET degradation. Based on the biochemical analysis, we propose that the wide substrate-binding pocket is critical for its excellent property on crystallized PET hydrolysis. Structure-guided site-directed mutagenesis exhibited improvement in PETase catalytic efficiency, providing valuable insight on how the molecular engineering of PETase can optimize its application in biocatalysis. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Characterization and optimization for detector systems of IGRINS

NASA Astrophysics Data System (ADS)

Jeong, Ueejeong; Chun, Moo-Young; Oh, Jae Sok; Park, Chan; Yuk, In-Soo; Oh, Heeyoung; Kim, Kang-Min; Ko, Kyeong Yeon; Pavel, Michael D.; Yu, Young Sam; Jaffe, Daniel T.

2014-07-01

IGRINS (Immersion GRating INfrared Spectrometer) is a high resolution wide-band infrared spectrograph developed by the Korea Astronomy and Space Science Institute (KASI) and the University of Texas at Austin (UT). This spectrograph has H-band and K-band science cameras and a slit viewing camera, all three of which use Teledyne's λc~2.5μm 2k×2k HgCdTe HAWAII-2RG CMOS detectors. The two spectrograph cameras employ science grade detectors, while the slit viewing camera includes an engineering grade detector. Teledyne's cryogenic SIDECAR ASIC boards and JADE2 USB interface cards were installed to control those detectors. We performed experiments to characterize and optimize the detector systems in the IGRINS cryostat. We present measurements and optimization of noise, dark current, and referencelevel stability obtained under dark conditions. We also discuss well depth, linearity and conversion gain measurements obtained using an external light source.

Visualization of Porphyrin-Based Photosensitizer Distribution from Fluorescence Images In Vivo Using an Optimized RGB Camera

NASA Astrophysics Data System (ADS)

Liu, L.; Huang, Zh.; Qiu, Zh.; Li, B.

2018-01-01

A handheld RGB camera was developed to monitor the in vivo distribution of porphyrin-based photosensitizer (PS) hematoporphyrin monomethyl ether (HMME) in blood vessels during photodynamic therapy (PDT). The focal length, f-number, International Standardization Organization (ISO) sensitivity, and shutter speed of the camera were optimized for the solution sample with various HMME concentrations. After the parameter optimization, it was found that the red intensity value of the fluorescence image was linearly related to the fluorescence intensity under investigated conditions. The RGB camera was then used to monitor the in vivo distribution of HMME in blood vessels in a skin-fold window chamber model. The red intensity value of the recorded RGB fluorescence image was found to be linearly correlated to HMME concentrations in the range 0-24 μM. Significant differences in the red to green intensity ratios were observed between the blood vessels and the surrounding tissue.

Structural insight into molecular mechanism of poly(ethylene terephthalate) degradation.

PubMed

Joo, Seongjoon; Cho, In Jin; Seo, Hogyun; Son, Hyeoncheol Francis; Sagong, Hye-Young; Shin, Tae Joo; Choi, So Young; Lee, Sang Yup; Kim, Kyung-Jin

2018-01-26

Plastics, including poly(ethylene terephthalate) (PET), possess many desirable characteristics and thus are widely used in daily life. However, non-biodegradability, once thought to be an advantage offered by plastics, is causing major environmental problem. Recently, a PET-degrading bacterium, Ideonella sakaiensis, was identified and suggested for possible use in degradation and/or recycling of PET. However, the molecular mechanism of PET degradation is not known. Here we report the crystal structure of I. sakaiensis PETase (IsPETase) at 1.5 Å resolution. IsPETase has a Ser-His-Asp catalytic triad at its active site and contains an optimal substrate binding site to accommodate four monohydroxyethyl terephthalate (MHET) moieties of PET. Based on structural and site-directed mutagenesis experiments, the detailed process of PET degradation into MHET, terephthalic acid, and ethylene glycol is suggested. Moreover, other PETase candidates potentially having high PET-degrading activities are suggested based on phylogenetic tree analysis of 69 PETase-like proteins.

WE-H-207A-03: The Universality of the Lognormal Behavior of [F-18]FLT PET SUV Measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scarpelli, M; Eickhoff, J; Perlman, S

Purpose: Log transforming [F-18]FDG PET standardized uptake values (SUVs) has been shown to lead to normal SUV distributions, which allows utilization of powerful parametric statistical models. This study identified the optimal transformation leading to normally distributed [F-18]FLT PET SUVs from solid tumors and offers an example of how normal distributions permits analysis of non-independent/correlated measurements. Methods: Forty patients with various metastatic diseases underwent up to six FLT PET/CT scans during treatment. Tumors were identified by nuclear medicine physician and manually segmented. Average uptake was extracted for each patient giving a global SUVmean (gSUVmean) for each scan. The Shapiro-Wilk test wasmore » used to test distribution normality. One parameter Box-Cox transformations were applied to each of the six gSUVmean distributions and the optimal transformation was found by selecting the parameter that maximized the Shapiro-Wilk test statistic. The relationship between gSUVmean and a serum biomarker (VEGF) collected at imaging timepoints was determined using a linear mixed effects model (LMEM), which accounted for correlated/non-independent measurements from the same individual. Results: Untransformed gSUVmean distributions were found to be significantly non-normal (p<0.05). The optimal transformation parameter had a value of 0.3 (95%CI: −0.4 to 1.6). Given the optimal parameter was close to zero (which corresponds to log transformation), the data were subsequently log transformed. All log transformed gSUVmean distributions were normally distributed (p>0.10 for all timepoints). Log transformed data were incorporated into the LMEM. VEGF serum levels significantly correlated with gSUVmean (p<0.001), revealing log-linear relationship between SUVs and underlying biology. Conclusion: Failure to account for correlated/non-independent measurements can lead to invalid conclusions and motivated transformation to normally distributed SUVs. The log transformation was found to be close to optimal and sufficient for obtaining normally distributed FLT PET SUVs. These transformations allow utilization of powerful LMEMs when analyzing quantitative imaging metrics.« less

Enhancement of multimodality texture-based prediction models via optimization of PET and MR image acquisition protocols: a proof of concept

NASA Astrophysics Data System (ADS)

Vallières, Martin; Laberge, Sébastien; Diamant, André; El Naqa, Issam

2017-11-01

Texture-based radiomic models constructed from medical images have the potential to support cancer treatment management via personalized assessment of tumour aggressiveness. While the identification of stable texture features under varying imaging settings is crucial for the translation of radiomics analysis into routine clinical practice, we hypothesize in this work that a complementary optimization of image acquisition parameters prior to texture feature extraction could enhance the predictive performance of texture-based radiomic models. As a proof of concept, we evaluated the possibility of enhancing a model constructed for the early prediction of lung metastases in soft-tissue sarcomas by optimizing PET and MR image acquisition protocols via computerized simulations of image acquisitions with varying parameters. Simulated PET images from 30 STS patients were acquired by varying the extent of axial data combined per slice (‘span’). Simulated T 1-weighted and T 2-weighted MR images were acquired by varying the repetition time and echo time in a spin-echo pulse sequence, respectively. We analyzed the impact of the variations of PET and MR image acquisition parameters on individual textures, and we investigated how these variations could enhance the global response and the predictive properties of a texture-based model. Our results suggest that it is feasible to identify an optimal set of image acquisition parameters to improve prediction performance. The model constructed with textures extracted from simulated images acquired with a standard clinical set of acquisition parameters reached an average AUC of 0.84 +/- 0.01 in bootstrap testing experiments. In comparison, the model performance significantly increased using an optimal set of image acquisition parameters (p = 0.04 ), with an average AUC of 0.89 +/- 0.01 . Ultimately, specific acquisition protocols optimized to generate superior radiomics measurements for a given clinical problem could be developed and standardized via dedicated computer simulations and thereafter validated using clinical scanners.

Investigation of Image Reconstruction Parameters of the Mediso nanoScan PC Small-Animal PET/CT Scanner for Two Different Positron Emitters Under NEMA NU 4-2008 Standards.

PubMed

Gaitanis, Anastasios; Kastis, George A; Vlastou, Elena; Bouziotis, Penelope; Verginis, Panayotis; Anagnostopoulos, Constantinos D

2017-08-01

The Tera-Tomo 3D image reconstruction algorithm (a version of OSEM), provided with the Mediso nanoScan® PC (PET8/2) small-animal positron emission tomograph (PET)/x-ray computed tomography (CT) scanner, has various parameter options such as total level of regularization, subsets, and iterations. Also, the acquisition time in PET plays an important role. This study aims to assess the performance of this new small-animal PET/CT scanner for different acquisition times and reconstruction parameters, for 2-deoxy-2-[ 18 F]fluoro-D-glucose ([ 18 F]FDG) and Ga-68, under the NEMA NU 4-2008 standards. Various image quality metrics were calculated for different realizations of [ 18 F]FDG and Ga-68 filled image quality (IQ) phantoms. [ 18 F]FDG imaging produced improved images over Ga-68. The best compromise for the optimization of all image quality factors is achieved for at least 30 min acquisition and image reconstruction with 52 iteration updates combined with a high regularization level. A high regularization level at 52 iteration updates and 30 min acquisition time were found to optimize most of the figures of merit investigated.

Robust real-time extraction of respiratory signals from PET list-mode data.

PubMed

Salomon, Andre; Zhang, Bin; Olivier, Patrick; Goedicke, Andreas

2018-05-01

Respiratory motion, which typically cannot simply be suspended during PET image acquisition, affects lesions' detection and quantitative accuracy inside or in close vicinity to the lungs. Some motion compensation techniques address this issue via pre-sorting ("binning") of the acquired PET data into a set of temporal gates, where each gate is assumed to be minimally affected by respiratory motion. Tracking respiratory motion is typically realized using dedicated hardware (e.g. using respiratory belts and digital cameras). Extracting respiratory signalsdirectly from the acquired PET data simplifies the clinical workflow as it avoids to handle additional signal measurement equipment. We introduce a new data-driven method "Combined Local Motion Detection" (CLMD). It uses the Time-of-Flight (TOF) information provided by state-of-the-art PET scanners in order to enable real-time respiratory signal extraction without additional hardware resources. CLMD applies center-of-mass detection in overlapping regions based on simple back-positioned TOF event sets acquired in short time frames. Following a signal filtering and quality-based pre-selection step, the remaining extracted individual position information over time is then combined to generate a global respiratory signal. The method is evaluated using 7 measured FDG studies from single and multiple scan positions of the thorax region, and it is compared to other software-based methods regarding quantitative accuracy and statistical noise stability. Correlation coefficients around 90% between the reference and the extracted signal have been found for those PET scans where motion affected features such as tumors or hot regions were present in the PET field-of-view. For PET scans with a quarter of typically applied radiotracer doses, the CLMD method still provides similar high correlation coefficients which indicates its robustness to noise. Each CLMD processing needed less than 0.4s in total on a standard multi-core CPU and thus provides a robust and accurate approach enabling real-time processing capabilities using standard PC hardware. © 2018 Institute of Physics and Engineering in Medicine.

Robust real-time extraction of respiratory signals from PET list-mode data

NASA Astrophysics Data System (ADS)

Salomon, André; Zhang, Bin; Olivier, Patrick; Goedicke, Andreas

2018-06-01

Respiratory motion, which typically cannot simply be suspended during PET image acquisition, affects lesions’ detection and quantitative accuracy inside or in close vicinity to the lungs. Some motion compensation techniques address this issue via pre-sorting (‘binning’) of the acquired PET data into a set of temporal gates, where each gate is assumed to be minimally affected by respiratory motion. Tracking respiratory motion is typically realized using dedicated hardware (e.g. using respiratory belts and digital cameras). Extracting respiratory signals directly from the acquired PET data simplifies the clinical workflow as it avoids handling additional signal measurement equipment. We introduce a new data-driven method ‘combined local motion detection’ (CLMD). It uses the time-of-flight (TOF) information provided by state-of-the-art PET scanners in order to enable real-time respiratory signal extraction without additional hardware resources. CLMD applies center-of-mass detection in overlapping regions based on simple back-positioned TOF event sets acquired in short time frames. Following a signal filtering and quality-based pre-selection step, the remaining extracted individual position information over time is then combined to generate a global respiratory signal. The method is evaluated using seven measured FDG studies from single and multiple scan positions of the thorax region, and it is compared to other software-based methods regarding quantitative accuracy and statistical noise stability. Correlation coefficients around 90% between the reference and the extracted signal have been found for those PET scans where motion affected features such as tumors or hot regions were present in the PET field-of-view. For PET scans with a quarter of typically applied radiotracer doses, the CLMD method still provides similar high correlation coefficients which indicates its robustness to noise. Each CLMD processing needed less than 0.4 s in total on a standard multi-core CPU and thus provides a robust and accurate approach enabling real-time processing capabilities using standard PC hardware.

Electroless plating Cu-Co-P polyalloy on UV/ozonolysis irradiated polyethylene terephthalate film and its corrosion resistance

NASA Astrophysics Data System (ADS)

Hou, Lei; Bi, Siyi; Zhao, Hang; Xu, Yumeng; Mu, Yuhang; Lu, Yinxiang

2017-05-01

High corrosion resistant Cu-Co-P coatings were firstly prepared on polyethylene terephthalate (PET) substrate by electroless plating in combination with UV/ozonolysis irradiation under optimized cobalt sulfate heptahydrate concentration, pH value, plating temperature and time. The copper polyalloy/PET composite can be obtained in three steps, namely: (i) the generation of oxygen-containing functionalities (carboxylic groups) onto PET surface through UV irradiation combined with ozone, (ii) Cu seeding catalysts were obtained after being immersed into cupric citrate and NaBH4 solutions subsequently, and (iii) Cu-Co-P polyalloy metallization using electroless plating bath. Attenuated total reflection fourier transformation infrared spectrometer (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), water contact angle measurement and energy dispersive X-ray analysis (EDAX) were utilized to track the surface changes during the whole process. The electroless plating conditions were optimized by an orthogonal experiment (L9(3)4) for Cu-Co-P coating as follows: CoSO4·7H2O addition of 0.08 M, pH value, plating temperature and time were set on 10.0, 35 °C and 25 min, respectively. Under the optimal conditions, copper polyalloy possessed high adhesive strength and the lowest surface resistance (8.06 Ω/sq), while maintaining reliability even after over 1000 times of bending and mechanical stress. The results of scanning electron microscope (SEM) and atomic force microscope (AFM) measurements showed that Cu-Co-P layer formed on PET surface was imparted with fine uniformity and high compactness. Electrochemical test revealed the optimized Cu-Co-P coatings exhibited high corrosion resistance in NaCl, NaOH and HCl solutions, respectively. The excellent electromagnetic interference shielding effectiveness (EMI SE >99.999% at frequency ranging from 30 MHz to 1000 MHz) of copper polyalloy/PET composites was confirmed by the spectrum analyzer. Therefore, this copper polyalloy will have potential applications in microelectronics packaging and coatings for anti-corrosion and electromagnetic interference shielding.

OpenPET: A Flexible Electronics System for Radiotracer Imaging

NASA Astrophysics Data System (ADS)

Moses, W. W.; Buckley, S.; Vu, C.; Peng, Q.; Pavlov, N.; Choong, W.-S.; Wu, J.; Jackson, C.

2010-10-01

We present the design for OpenPET, an electronics readout system designed for prototype radiotracer imaging instruments. The critical requirements are that it has sufficient performance, channel count, channel density, and power consumption to service a complete camera, and yet be simple, flexible, and customizable enough to be used with almost any detector or camera design. An important feature of this system is that each analog input is processed independently. Each input can be configured to accept signals of either polarity as well as either differential or ground referenced signals. Each signal is digitized by a continuously sampled ADC, which is processed by an FPGA to extract pulse height information. A leading edge discriminator creates a timing edge that is “time stamped” by a TDC implemented inside the FPGA. This digital information from each channel is sent to an FPGA that services 16 analog channels, and information from multiple channels is processed by this FPGA to perform logic for crystal lookup, DOI calculation, calibration, etc. As all of this processing is controlled by firmware and software, it can be modified/customized easily. The system is open source, meaning that all technical data (specifications, schematics and board layout files, source code, and instructions) will be publicly available.

Multi-modality imaging of tumor phenotype and response to therapy

NASA Astrophysics Data System (ADS)

Nyflot, Matthew J.

2011-12-01

Imaging and radiation oncology have historically been closely linked. However, the vast majority of techniques used in the clinic involve anatomical imaging. Biological imaging offers the potential for innovation in the areas of cancer diagnosis and staging, radiotherapy target definition, and treatment response assessment. Some relevant imaging techniques are FDG PET (for imaging cellular metabolism), FLT PET (proliferation), CuATSM PET (hypoxia), and contrast-enhanced CT (vasculature and perfusion). Here, a technique for quantitative spatial correlation of tumor phenotype is presented for FDG PET, FLT PET, and CuATSM PET images. Additionally, multimodality imaging of treatment response with FLT PET, CuATSM, and dynamic contrast-enhanced CT is presented, in a trial of patients receiving an antiangiogenic agent (Avastin) combined with cisplatin and radiotherapy. Results are also presented for translational applications in animal models, including quantitative assessment of proliferative response to cetuximab with FLT PET and quantification of vascular volume with a blood-pool contrast agent (Fenestra). These techniques have clear applications to radiobiological research and optimized treatment strategies, and may eventually be used for personalized therapy for patients.

Towards improved hardware component attenuation correction in PET/MR hybrid imaging

NASA Astrophysics Data System (ADS)

Paulus, D. H.; Tellmann, L.; Quick, H. H.

2013-11-01

In positron emission tomography/computed tomography (PET/CT) hybrid imaging attenuation correction (AC) of the patient tissue and patient table is performed by converting the CT-based Hounsfield units (HU) to linear attenuation coefficients (LAC) of PET. When applied to the new field of hardware component AC in PET/magnetic resonance (MR) hybrid imaging, this conversion method may result in local overcorrection of PET activity values. The aim of this study thus was to optimize the conversion parameters for CT-based AC of hardware components in PET/MR. Systematic evaluation and optimization of the HU to LAC conversion parameters has been performed for the hardware component attenuation map (µ-map) of a flexible radiofrequency (RF) coil used in PET/MR imaging. Furthermore, spatial misregistration of this RF coil to its µ-map was simulated by shifting the µ-map in different directions and the effect on PET quantification was evaluated. Measurements of a PET NEMA standard emission phantom were performed on an integrated hybrid PET/MR system. Various CT parameters were used to calculate different µ-maps for the flexible RF coil and to evaluate the impact on the PET activity concentration. A 511 keV transmission scan of the local RF coil was used as standard of reference to adapt the slope of the conversion from HUs to LACs at 511 keV. The average underestimation of the PET activity concentration due to the non-attenuation corrected RF coil in place was calculated to be 5.0% in the overall phantom. When considering attenuation only in the upper volume of the phantom, the average difference to the reference scan without RF coil is 11.0%. When the PET/CT conversion is applied, an average overestimation of 3.1% (without extended CT scale) and 4.2% (with extended CT scale) is observed in the top volume of the NEMA phantom. Using the adapted conversion resulting from this study, the deviation in the top volume of the phantom is reduced to -0.5% and shows the lowest standard deviation inside the phantom in comparison to all other conversions. Simulation of a µ-map misregistration shows acceptable results for shifts below 5 mm for the flexible surface RF coil. The adapted conversion from HUs to LAC at 511 keV within this study can improve hardware component AC in PET/MR hybrid imaging as shown for a flexible RF surface coil. Furthermore, these results have a direct impact on the improvement of the hardware component AC of the examined flexible RF coil in conjunction with position determination.

Evaluation of multispectral plenoptic camera

NASA Astrophysics Data System (ADS)

Meng, Lingfei; Sun, Ting; Kosoglow, Rich; Berkner, Kathrin

2013-01-01

Plenoptic cameras enable capture of a 4D lightfield, allowing digital refocusing and depth estimation from data captured with a compact portable camera. Whereas most of the work on plenoptic camera design has been based a simplistic geometric-optics-based characterization of the optical path only, little work has been done of optimizing end-to-end system performance for a specific application. Such design optimization requires design tools that need to include careful parameterization of main lens elements, as well as microlens array and sensor characteristics. In this paper we are interested in evaluating the performance of a multispectral plenoptic camera, i.e. a camera with spectral filters inserted into the aperture plane of the main lens. Such a camera enables single-snapshot spectral data acquisition.1-3 We first describe in detail an end-to-end imaging system model for a spectrally coded plenoptic camera that we briefly introduced in.4 Different performance metrics are defined to evaluate the spectral reconstruction quality. We then present a prototype which is developed based on a modified DSLR camera containing a lenslet array on the sensor and a filter array in the main lens. Finally we evaluate the spectral reconstruction performance of a spectral plenoptic camera based on both simulation and measurements obtained from the prototype.

Evaluation and optimization of occupational eye lens dosimetry during positron emission tomography (PET) procedures.

PubMed

Guiu-Souto, Jacobo; Sánchez-García, Manuel; Vázquez-Vázquez, Rubén; Otero, Carlos; Luna, Victor; Mosquera, Javier; Busto, Ramón Lobato; Aguiar, Pablo; Ruibal, Álvaro; Pardo-Montero, Juan; Pombar-Cameán, Miguel

2016-06-01

The last recommendations of the International Commission on Radiological Protection for eye lens dose suggest an important reduction on the radiation limits associated with early and late tissue reactions. The aim of this work is to quantify and optimize the eye lens dose associated to nurse staff during positron emission tomography (PET) procedures. PET is one of the most important diagnostic methods of oncological and neurological cancer disease involving an important number of workers exposed to the high energy isotope F-18. We characterize the relevant stages as preparation and administration of monodose syringes in terms of occupational dose. A direct reading silicon dosimeter was used to measure the lens dose to staff. The highest dose of radiation was observed during preparation of the fluorodesoxyglucose (FDG) syringes. By optimizing a suitable vials' distribution of FDG we find an important reduction in occupational doses. Extrapolation of our data to other clinical scenarios indicates that, depending on the work load and/or syringes activity, safety limits of the dose might be exceeded.

Low-count PET image restoration using sparse representation

NASA Astrophysics Data System (ADS)

Li, Tao; Jiang, Changhui; Gao, Juan; Yang, Yongfeng; Liang, Dong; Liu, Xin; Zheng, Hairong; Hu, Zhanli

2018-04-01

In the field of positron emission tomography (PET), reconstructed images are often blurry and contain noise. These problems are primarily caused by the low resolution of projection data. Solving this problem by improving hardware is an expensive solution, and therefore, we attempted to develop a solution based on optimizing several related algorithms in both the reconstruction and image post-processing domains. As sparse technology is widely used, sparse prediction is increasingly applied to solve this problem. In this paper, we propose a new sparse method to process low-resolution PET images. Two dictionaries (D1 for low-resolution PET images and D2 for high-resolution PET images) are learned from a group real PET image data sets. Among these two dictionaries, D1 is used to obtain a sparse representation for each patch of the input PET image. Then, a high-resolution PET image is generated from this sparse representation using D2. Experimental results indicate that the proposed method exhibits a stable and superior ability to enhance image resolution and recover image details. Quantitatively, this method achieves better performance than traditional methods. This proposed strategy is a new and efficient approach for improving the quality of PET images.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Choong, W. -S.; Abu-Nimeh, F.; Moses, W. W.

Here, we present a 16-channel front-end readout board for the OpenPET electronics system. A major task in developing a nuclear medical imaging system, such as a positron emission computed tomograph (PET) or a single-photon emission computed tomograph (SPECT), is the electronics system. While there are a wide variety of detector and camera design concepts, the relatively simple nature of the acquired data allows for a common set of electronics requirements that can be met by a flexible, scalable, and high-performance OpenPET electronics system. The analog signals from the different types of detectors used in medical imaging share similar characteristics, whichmore » allows for a common analog signal processing. The OpenPET electronics processes the analog signals with Detector Boards. Here we report on the development of a 16-channel Detector Board. Each signal is digitized by a continuously sampled analog-to-digital converter (ADC), which is processed by a field programmable gate array (FPGA) to extract pulse height information. A leading edge discriminator creates a timing edge that is "time stamped" by a time-to-digital converter (TDC) implemented inside the FPGA. In conclusion, this digital information from each channel is sent to an FPGA that services 16 analog channels, and then information from multiple channels is processed by this FPGA to perform logic for crystal lookup, DOI calculation, calibration, etc.« less

Hard beta and gamma emissions of 124I. Impact on occupational dose in PET/CT.

PubMed

Kemerink, G J; Franssen, R; Visser, M G W; Urbach, C J A; Halders, S G E A; Frantzen, M J; Brans, B; Teule, G J J; Mottaghy, F M

2011-01-01

The hard beta and gamma radiation of 124I can cause high doses to PET/CT workers. In this study we tried to quantify this occupational exposure and to optimize radioprotection. Thin MCP-Ns thermoluminescent dosimeters suitable for measuring beta and gamma radiation were used for extremity dosimetry, active personal dosimeters for whole-body dosimetry. Extremity doses were determined during dispensing of 124I and oral administration of the activity to the patient, the body dose during all phases of the PET/CT procedure. In addition, dose rates of vials and syringes as used in clinical practice were measured. The procedure for dispensing 124I was optimized using newly developed shielding. Skin dose rates up to 100 mSv/min were measured when in contact with the manufacturer's vial containing 370 MBq of 124I. For an unshielded 5 ml syringe the positron skin dose was about seven times the gamma dose. Before optimization of the preparation of 124I, using an already reasonably safe technique, the highest mean skin dose caused by handling 370 MBq was 1.9 mSv (max. 4.4 mSv). After optimization the skin dose was below 0.2 mSv. The highly energetic positrons emitted by 124I can cause high skin doses if radioprotection is poor. Under optimized conditions occupational doses are acceptable. Education of workers is of paramount importance.

A 31-Channel MR Brain Array Coil Compatible with Positron Emission Tomography

PubMed Central

Sander, Christin Y.; Keil, Boris; Chonde, Daniel B.; Rosen, Bruce R.; Catana, Ciprian; Wald, Lawrence L.

2014-01-01

Purpose Simultaneous acquisition of MR and PET images requires the placement of the MR detection coil inside the PET detector ring where it absorbs and scatters photons. This constraint is the principal barrier to achieving optimum sensitivity on each modality. Here, we present a 31-channel PET-compatible brain array coil with reduced attenuation but improved MR sensitivity. Methods A series of component tests were performed to identify tradeoffs between PET and MR performance. Aspects studied include the remote positioning of preamplifiers, coax size, coil trace size/material, and plastic housing. We then maximized PET performance at minimal cost to MR sensitivity. The coil was evaluated for MR performance (SNR, g-factor) and PET attenuation. Results The coil design showed an improvement in attenuation by 190% (average) compared to conventional 32-channel arrays, and no loss in MR SNR. Moreover, the 31-channel coil displayed an SNR improvement of 230% (cortical ROI) compared to a PET-optimized 8-channel array with similar attenuation properties. Implementing attenuation correction of the 31-channel array successfully removed PET artifacts, which were comparable to those of the 8-channel array. Conclusion The design of the 31-channel PET-compatible coil enables higher sensitivity for PET/MR imaging, paving the way for novel applications in this hybrid-imaging domain. PMID:25046699

Dual-modality brain PET-CT image segmentation based on adaptive use of functional and anatomical information.

PubMed

Xia, Yong; Eberl, Stefan; Wen, Lingfeng; Fulham, Michael; Feng, David Dagan

2012-01-01

Dual medical imaging modalities, such as PET-CT, are now a routine component of clinical practice. Medical image segmentation methods, however, have generally only been applied to single modality images. In this paper, we propose the dual-modality image segmentation model to segment brain PET-CT images into gray matter, white matter and cerebrospinal fluid. This model converts PET-CT image segmentation into an optimization process controlled simultaneously by PET and CT voxel values and spatial constraints. It is innovative in the creation and application of the modality discriminatory power (MDP) coefficient as a weighting scheme to adaptively combine the functional (PET) and anatomical (CT) information on a voxel-by-voxel basis. Our approach relies upon allowing the modality with higher discriminatory power to play a more important role in the segmentation process. We compared the proposed approach to three other image segmentation strategies, including PET-only based segmentation, combination of the results of independent PET image segmentation and CT image segmentation, and simultaneous segmentation of joint PET and CT images without an adaptive weighting scheme. Our results in 21 clinical studies showed that our approach provides the most accurate and reliable segmentation for brain PET-CT images. Copyright © 2011 Elsevier Ltd. All rights reserved.

Optimization of scan initiation timing after 11C-methionine administration for the diagnosis of suspected recurrent brain tumors.

PubMed

Nakajima, Reiko; Abe, Koichiro; Momose, Mitsuru; Fukushima, Kenji; Matsuo, Yuka; Kimura, Ken; Kondo, Chisato; Sakai, Shuji

2017-02-01

11 C-Methionine (MET) positron emission tomography (PET) imaging is a valuable technique for the evaluation of primary and recurrent brain tumors. Many studies have used MET-PET for data acquisition starting at 20 min after the tracer injection, while others have used scan initiation times at 5-15 min postinjection. No previous studies have identified the best acquisition timing during MET-PET imaging for suspected recurrent brain tumors. Here we sought to determine the optimal scan initiating timing after MET administration for the detection of recurrent brain tumors. Twenty-three consecutive patients with suspected recurrent brain tumors underwent MET-PET examinations. Brain PET images were reconstructed from the four serial data sets (10-15, 15-20, 20-25, and 25-30 min postinjection) that were obtained using the list-mode acquisition technique. We determined the maximal standardized uptake values (SUVmax) of the target lesions and the target-to-normal-tissue ratios (TNRs), calculated as the SUVmax to the SUVmean of a region of interest placed on the normal contralateral frontal cortex. Target lesions without significant MET uptake were excluded. Thirty-one lesions from 23 patients were enrolled. There were no significant differences in MET SUVmax or TNR values among the PET images that were reconstructed with the data extracted from the four phases postinjection. The MET uptake in the suspected recurrent brain tumors was comparable among all data extraction time phases from 10 to 30 min postinjection. The scan initiation time of MET-PET at 10 min after the injection is allowable for the detection of recurrent brain tumors. The registration identification number of the original study is 1002.

4D-Listmode-PET-CT and 4D-CT for optimizing PTV margins in gastric lymphoma : Determination of intra- and interfractional gastric motion.

PubMed

Reinartz, Gabriele; Haverkamp, Uwe; Wullenkord, Ramona; Lehrich, Philipp; Kriz, Jan; Büther, Florian; Schäfers, Klaus; Schäfers, Michael; Eich, Hans Theodor

2016-05-01

New imaging protocols for radiotherapy in localized gastric lymphoma were evaluated to optimize planning target volume (PTV) margin and determine intra-/interfractional variation of the stomach. Imaging of 6 patients was explored prospectively. Intensity-modulated radiotherapy (IMRT) planning was based on 4D/3D imaging of computed tomography (CT) and positron-emission tomography (PET)-CT. Static and motion gross tumor volume (sGTV and mGTV, respectively) were distinguished by defining GTV (empty stomach), clinical target volume (CTV = GTV + 5 mm margin), PTV (GTV + 10/15/20/25 mm margins)  plus paraaortic lymph nodes and proximal duodenum. Overlap of 4D-Listmode-PET-based mCTV with 3D-CT-based PTV (increasing margins) and V95/D95 of mCTV were evaluated. Gastric shifts were determined using online cone-beam CT. Dose contribution to organs at risk was assessed. The 4D data demonstrate considerable intra-/interfractional variation of the stomach, especially along the vertical axis. Conventional 3D-CT planning utilizing advancing PTV margins of 10/15/20/25 mm resulted in rising dose coverage of mCTV (4D-Listmode-PET-Summation-CT) and rising D95 and V95 of mCTV. A PTV margin of 15 mm was adequate in 3 of 6 patients, a PTV margin of 20 mm was adequate in 4 of 6 patients, and a PTV margin of 25 mm was adequate in 5 of 6 patients. IMRT planning based on 4D-PET-CT/4D-CT together with online cone-beam CT is advisable to individualize the PTV margin and optimize target coverage in gastric lymphoma.

Quantitative analysis of a reconstruction method for fully three-dimensional PET.

PubMed

Suckling, J; Ott, R J; Deehan, B J

1992-03-01

The major advantage of positron emission tomography (PET) using large area planar detectors over scintillator-based commercial ring systems is the potentially larger (by a factor of two or three) axial field-of-view (FOV). However, to achieve the space invariance of the point spread function necessary for Fourier filtering a polar angle rejection criterion is applied to the data during backprojection resulting in a trade-off between FOV size and sensitivity. A new algorithm due to Defrise and co-workers developed for list-mode data overcomes this problem with a solution involving the division of the image into several subregions. A comparison between the existing backprojection-then-filter algorithm and the new method (with three subregions) has been made using both simulated and real data collected from the MUP-PET positron camera. Signal-to-noise analysis reveals that improvements of up to a factor of 1.4 are possible resulting from an increased data usage of up to a factor of 2.5 depending on the axial extent of the imaged object. Quantitation is also improved.

Joint penalized-likelihood reconstruction of time-activity curves and regions-of-interest from projection data in brain PET

NASA Astrophysics Data System (ADS)

Krestyannikov, E.; Tohka, J.; Ruotsalainen, U.

2008-06-01

This paper presents a novel statistical approach for joint estimation of regions-of-interest (ROIs) and the corresponding time-activity curves (TACs) from dynamic positron emission tomography (PET) brain projection data. It is based on optimizing the joint objective function that consists of a data log-likelihood term and two penalty terms reflecting the available a priori information about the human brain anatomy. The developed local optimization strategy iteratively updates both the ROI and TAC parameters and is guaranteed to monotonically increase the objective function. The quantitative evaluation of the algorithm is performed with numerically and Monte Carlo-simulated dynamic PET brain data of the 11C-Raclopride and 18F-FDG tracers. The results demonstrate that the method outperforms the existing sequential ROI quantification approaches in terms of accuracy, and can noticeably reduce the errors in TACs arising due to the finite spatial resolution and ROI delineation.

Quantitative multimodality imaging in cancer research and therapy.

PubMed

Yankeelov, Thomas E; Abramson, Richard G; Quarles, C Chad

2014-11-01

Advances in hardware and software have enabled the realization of clinically feasible, quantitative multimodality imaging of tissue pathophysiology. Earlier efforts relating to multimodality imaging of cancer have focused on the integration of anatomical and functional characteristics, such as PET-CT and single-photon emission CT (SPECT-CT), whereas more-recent advances and applications have involved the integration of multiple quantitative, functional measurements (for example, multiple PET tracers, varied MRI contrast mechanisms, and PET-MRI), thereby providing a more-comprehensive characterization of the tumour phenotype. The enormous amount of complementary quantitative data generated by such studies is beginning to offer unique insights into opportunities to optimize care for individual patients. Although important technical optimization and improved biological interpretation of multimodality imaging findings are needed, this approach can already be applied informatively in clinical trials of cancer therapeutics using existing tools. These concepts are discussed herein.

A prototype PET/SPECT/X-rays scanner dedicated for whole body small animal studies.

PubMed

Rouchota, Maritina; Georgiou, Maria; Fysikopoulos, Eleftherios; Fragogeorgi, Eirini; Mikropoulos, Konstantinos; Papadimitroulas, Panagiotis; Kagadis, George; Loudos, George

2017-01-01

To present a prototype tri-modal imaging system, consisting of a single photon emission computed tomography (SPET), a positron emission tomography (PET), and a computed tomography (CT) subsystem, evaluated in planar mode. The subsystems are mounted on a rotating gantry, so as to be able to allow tomographic imaging in the future. The system, designed and constructed by our group, allows whole body mouse imaging of competent performance and is currently, to the best of our knowledge, unequaled in a national and regional level. The SPET camera is based on two Position Sensitive Photomultiplier Tubes (PSPMT), coupled to a pixilated Sodium Iodide activated with Thallium (NaI(Tl)) scintillator, having an active area of 5x10cm 2 . The dual head PET camera is also based on two pairs of PSPMT, coupled to pixelated berillium germanium oxide (BGO) scintillators, having an active area of 5x10cm 2 . The X-rays system consists of a micro focus X-rays tube and a complementary metal-oxide-semiconductor (CMOS) detector, having an active area of 12x12cm 2 . The scintigraphic mode has a spatial resolution of 1.88mm full width at half maximum (FWHM) and a sensitivity of 107.5cpm/0.037MBq at the collimator surface. The coincidence PET mode has an average spatial resolution of 3.5mm (FWHM) and a peak sensitivity of 29.9cpm/0.037MBq. The X-rays spatial resolution is 3.5lp/mm and the contrast discrimination function value is lower than 2%. A compact tri-modal system was successfully built and evaluated for planar mode operation. The system has an efficient performance, allowing accurate and informative anatomical and functional imaging, as well as semi-quantitative results. Compared to other available systems, it provides a moderate but comparable performance, at a fraction of the cost and complexity. It is fully open, scalable and its main purpose is to support groups on a national and regional level and provide an open technological platform to study different detector components and acquisition strategies.

Single-snapshot 2D color measurement by plenoptic imaging system

NASA Astrophysics Data System (ADS)

Masuda, Kensuke; Yamanaka, Yuji; Maruyama, Go; Nagai, Sho; Hirai, Hideaki; Meng, Lingfei; Tosic, Ivana

2014-03-01

Plenoptic cameras enable capture of directional light ray information, thus allowing applications such as digital refocusing, depth estimation, or multiband imaging. One of the most common plenoptic camera architectures contains a microlens array at the conventional image plane and a sensor at the back focal plane of the microlens array. We leverage the multiband imaging (MBI) function of this camera and develop a single-snapshot, single-sensor high color fidelity camera. Our camera is based on a plenoptic system with XYZ filters inserted in the pupil plane of the main lens. To achieve high color measurement precision of this system, we perform an end-to-end optimization of the system model that includes light source information, object information, optical system information, plenoptic image processing and color estimation processing. Optimized system characteristics are exploited to build an XYZ plenoptic colorimetric camera prototype that achieves high color measurement precision. We describe an application of our colorimetric camera to color shading evaluation of display and show that it achieves color accuracy of ΔE<0.01.

J-PET detector system for studies of the electron-positron annihilations

NASA Astrophysics Data System (ADS)

Pawlik-Niedźwiecka, M.; Khreptak, O.; Gajos, A.; Wieczorek, A.; Alfs, D.; Bednarski, T.; Białas, P.; Curceanu, C.; Czerwiński, E.; Dulski, K.; Głowacz, B.; Gupta-Sharma, N.; Gorgol, M.; Hiesmayr, B. C.; Jasińska, B.; Kamińska, D.; Korcyl, G.; Kowalski, P.; Krzmień, W.; Krawczyk, N.; Kubicz, E.; Mohammed, M.; Niedźwiecki, Sz.; Raczyński, L.; Rudy, Z.; Silarski, M.; Wiślicki, W.; Zgardzińska, B.; Zieliński, M.; Moskal, P.

2016-11-01

Jagiellonian Positron Emission Tomograph (J-PET) has been recently constructed at the Jagiellonian University as a prototype of a cost-effective scanner for the metabolic imaging of the whole human body. J-PET detector is optimized for the measurement of momentum and polarization of photons from the electron-positron annihilations. It is built out of strips of plastic scintillators, forming three cylindrical layers. As detector of gamma quanta it will be used for studies of discrete symmetries and multiparticle entanglement of photons originating from the decays of ortho-positronium atoms.

Development of dose delivery verification by PET imaging of photonuclear reactions following high energy photon therapy

NASA Astrophysics Data System (ADS)

Janek, S.; Svensson, R.; Jonsson, C.; Brahme, A.

2006-11-01

A method for dose delivery monitoring after high energy photon therapy has been investigated based on positron emission tomography (PET). The technique is based on the activation of body tissues by high energy bremsstrahlung beams, preferably with energies well above 20 MeV, resulting primarily in 11C and 15O but also 13N, all positron-emitting radionuclides produced by photoneutron reactions in the nuclei of 12C, 16O and 14N. A PMMA phantom and animal tissue, a frozen hind leg of a pig, were irradiated to 10 Gy and the induced positron activity distributions were measured off-line in a PET camera a couple of minutes after irradiation. The accelerator used was a Racetrack Microtron at the Karolinska University Hospital using 50 MV scanned photon beams. From photonuclear cross-section data integrated over the 50 MV photon fluence spectrum the predicted PET signal was calculated and compared with experimental measurements. Since measured PET images change with time post irradiation, as a result of the different decay times of the radionuclides, the signals from activated 12C, 16O and 14N within the irradiated volume could be separated from each other. Most information is obtained from the carbon and oxygen radionuclides which are the most abundant elements in soft tissue. The predicted and measured overall positron activities are almost equal (-3%) while the predicted activity originating from nitrogen is overestimated by almost a factor of two, possibly due to experimental noise. Based on the results obtained in this first feasibility study the great value of a combined radiotherapy-PET-CT unit is indicated in order to fully exploit the high activity signal from oxygen immediately after treatment and to avoid patient repositioning. With an RT-PET-CT unit a high signal could be collected even at a dose level of 2 Gy and the acquisition time for the PET could be reduced considerably. Real patient dose delivery verification by means of PET imaging seems to be applicable provided that biological transport processes such as capillary blood flow containing mobile 15O and 11C in the activated tissue volume can be accounted for.

PET-Probe: Evaluation of Technical Performance and Clinical Utility of a Handheld High-Energy Gamma Probe in Oncologic Surgery.

PubMed

Gulec, Seza A; Daghighian, Farhad; Essner, Richard

2016-12-01

Positron emission tomography (PET) has become an invaluable part of patient evaluation in surgical oncology. PET is less than optimal for detecting lesions <1 cm, and the intraoperative localization of small PET-positive lesions can be challenging as a result of difficulties in surgical exposure. We undertook this investigation to assess the utility of a handheld high-energy gamma probe (PET-Probe) for intraoperative identification of 18 F-deoxyglucose (FDG)-avid tumors. Forty patients underwent a diagnostic whole-body FDG-PET scan for consideration for surgical exploration and resection. Before surgery, all patients received an intravenous injection of 7 to 10 mCi of FDG. At surgery, the PET-Probe was used to determine absolute counts per second at the known tumor site(s) demonstrated by whole-body PET and at adjacent normal tissue (at least 4 cm away from tumor-bearing sites). Tumor-to-background ratios were calculated. Thirty-two patients (80%) underwent PET-Probe-guided surgery with therapeutic intent in a recurrent or metastatic disease setting. Eight patients underwent surgery for diagnostic exploration. Anatomical locations of the PET-identified lesions were neck and supraclavicular (n = 8), axilla (n = 5), groin and deep iliac (n = 4), trunk and extremity soft tissue (n = 3), abdominal and retroperitoneal (n = 19), and lung (n = 2). PET-Probe detected all PET-positive lesions. The PET-Probe was instrumental in localization of lesions in 15 patients that were not immediately apparent by surgical exploration. The PET-Probe identified all lesions demonstrated by PET scanning and, in selected cases, was useful in localizing FDG-avid disease not seen with conventional PET scanning.

Use of a microscope-mounted wide-angle point of view camera to record optimal hand position in ocular surgery.

PubMed

Gooi, Patrick; Ahmed, Yusuf; Ahmed, Iqbal Ike K

2014-07-01

We describe the use of a microscope-mounted wide-angle point-of-view camera to record optimal hand positions in ocular surgery. The camera is mounted close to the objective lens beneath the surgeon's oculars and faces the same direction as the surgeon, providing a surgeon's view. A wide-angle lens enables viewing of both hands simultaneously and does not require repositioning the camera during the case. Proper hand positioning and instrument placement through microincisions are critical for effective and atraumatic handling of tissue within the eye. Our technique has potential in the assessment and training of optimal hand position for surgeons performing intraocular surgery. It is an innovative way to routinely record instrument and operating hand positions in ophthalmic surgery and has minimal requirements in terms of cost, personnel, and operating-room space. No author has a financial or proprietary interest in any material or method mentioned. Copyright © 2014 ASCRS and ESCRS. Published by Elsevier Inc. All rights reserved.

Free-viewpoint video of human actors using multiple handheld Kinects.

PubMed

Ye, Genzhi; Liu, Yebin; Deng, Yue; Hasler, Nils; Ji, Xiangyang; Dai, Qionghai; Theobalt, Christian

2013-10-01

We present an algorithm for creating free-viewpoint video of interacting humans using three handheld Kinect cameras. Our method reconstructs deforming surface geometry and temporal varying texture of humans through estimation of human poses and camera poses for every time step of the RGBZ video. Skeletal configurations and camera poses are found by solving a joint energy minimization problem, which optimizes the alignment of RGBZ data from all cameras, as well as the alignment of human shape templates to the Kinect data. The energy function is based on a combination of geometric correspondence finding, implicit scene segmentation, and correspondence finding using image features. Finally, texture recovery is achieved through jointly optimization on spatio-temporal RGB data using matrix completion. As opposed to previous methods, our algorithm succeeds on free-viewpoint video of human actors under general uncontrolled indoor scenes with potentially dynamic background, and it succeeds even if the cameras are moving.

Optimizing a 18F-NaF and 18F-FDG cocktail for PET assessment of metastatic castration-resistant prostate cancer

PubMed Central

Simoncic, Urban; Perlman, Scott; Liu, Glenn; Jeraj, Robert

2015-01-01

Background The 18F-NaF/18F-FDG cocktail PET/CT imaging has been proposed for patients with osseous metastases. This work aimed to optimize the cocktail composition for patients with metastatic castrate-resistant prostate cancer (mCRPC). Materials and methods Study was done on 6 patients with mCRPC that had analyzed a total of 26 lesions. Patients had 18F-NaF and 18F-FDG injections separated in time. Dynamic PET/CT imaging recorded uptake time course for both tracers into osseous metastases. 18F-NaF and 18F-FDG uptakes were decoupled by kinetic analysis, which enabled calculation of 18F-NaF and 18F-FDG Standardized Uptake Value (SUV) images. Peak, mean and total SUVs were evaluated for both tracers and all visible lesions. The 18F-NaF/18F-FDG cocktail was optimized under the assumption that contribution of both tracers to the image formation should be equal. SUV images for combined 18F-NaF/18F-FDG cocktail PET/CT imaging were generated for cocktail compositions with 18F-NaF:18F-FDG ratio varying from 1:8 to 1:2. Results The 18F-NaF peak and mean SUVs were on average 4-5 times higher than the 18F-FDG peak and mean SUVs, with inter-lesion coefficient-of-variations (COV) of 20%. 18F-NaF total SUV was on average 7 times higher than the 18F-FDG total SUV. When the 18F-NaF:18F-FDG ratio changed from 1:8 to 1:2, typical SUV on generated PET images increased by 50%, while change in uptake visual pattern was hardly noticeable. Conclusion The 18F-NaF/18F-FDG cocktail has equal contributions of both tracers to the image formation when the 18F-NaF:18F-FDG ratio is 1:5. Therefore we propose this ratio as the optimal cocktail composition for mCRPC patients. We also urge to strictly control the 18F-NaF/18F-FDG cocktail composition in any 18F-NaF/18F-FDG cocktail PET/CT exams. PMID:26378490

Impacts of Intelligent Automated Quality Control on a Small Animal APD-Based Digital PET Scanner

NASA Astrophysics Data System (ADS)

Charest, Jonathan; Beaudoin, Jean-François; Bergeron, Mélanie; Cadorette, Jules; Arpin, Louis; Lecomte, Roger; Brunet, Charles-Antoine; Fontaine, Réjean

2016-10-01

Stable system performance is mandatory to warrant the accuracy and reliability of biological results relying on small animal positron emission tomography (PET) imaging studies. This simple requirement sets the ground for imposing routine quality control (QC) procedures to keep PET scanners at a reliable optimal performance level. However, such procedures can become burdensome to implement for scanner operators, especially taking into account the increasing number of data acquisition channels in newer generation PET scanners. In systems using pixel detectors to achieve enhanced spatial resolution and contrast-to-noise ratio (CNR), the QC workload rapidly increases to unmanageable levels due to the number of independent channels involved. An artificial intelligence based QC system, referred to as Scanner Intelligent Diagnosis for Optimal Performance (SIDOP), was proposed to help reducing the QC workload by performing automatic channel fault detection and diagnosis. SIDOP consists of four high-level modules that employ machine learning methods to perform their tasks: Parameter Extraction, Channel Fault Detection, Fault Prioritization, and Fault Diagnosis. Ultimately, SIDOP submits a prioritized faulty channel list to the operator and proposes actions to correct them. To validate that SIDOP can perform QC procedures adequately, it was deployed on a LabPET™ scanner and multiple performance metrics were extracted. After multiple corrections on sub-optimal scanner settings, a 8.5% (with a 95% confidence interval (CI) of [7.6, 9.3]) improvement in the CNR, a 17.0% (CI: [15.3, 18.7]) decrease of the uniformity percentage standard deviation, and a 6.8% gain in global sensitivity were observed. These results confirm that SIDOP can indeed be of assistance in performing QC procedures and restore performance to optimal figures.

An optimal algorithm for reconstructing images from binary measurements

NASA Astrophysics Data System (ADS)

Yang, Feng; Lu, Yue M.; Sbaiz, Luciano; Vetterli, Martin

2010-01-01

We have studied a camera with a very large number of binary pixels referred to as the gigavision camera [1] or the gigapixel digital film camera [2, 3]. Potential advantages of this new camera design include improved dynamic range, thanks to its logarithmic sensor response curve, and reduced exposure time in low light conditions, due to its highly sensitive photon detection mechanism. We use maximum likelihood estimator (MLE) to reconstruct a high quality conventional image from the binary sensor measurements of the gigavision camera. We prove that when the threshold T is "1", the negative loglikelihood function is a convex function. Therefore, optimal solution can be achieved using convex optimization. Base on filter bank techniques, fast algorithms are given for computing the gradient and the multiplication of a vector and Hessian matrix of the negative log-likelihood function. We show that with a minor change, our algorithm also works for estimating conventional images from multiple binary images. Numerical experiments with synthetic 1-D signals and images verify the effectiveness and quality of the proposed algorithm. Experimental results also show that estimation performance can be improved by increasing the oversampling factor or the number of binary images.

Postoperative PET/CT and target delineation before adjuvant radiotherapy in patients with oral cavity squamous cell carcinoma.

PubMed

Dutta, Pinaki R; Riaz, Nadeem; McBride, Sean; Morris, Luc G; Patel, Snehal; Ganly, Ian; Wong, Richard J; Palmer, Frank; Schöder, Heiko; Lee, Nancy

2016-04-01

The purpose of this study was for us to present our evaluation of the effectiveness of positron emission tomography (PET)/CT imaging in postoperative patients with oral cavity squamous cell carcinoma (SCC) before initiating adjuvant radiation therapy. Treatment planning PET/CT scans were obtained in 44 patients with oral cavity SCC receiving adjuvant radiation. We identified target areas harboring macroscopic disease requiring higher radiation doses or additional surgery. Fourteen PET/CT scans were abnormal. Thirteen patients underwent surgery and/or biopsy, increased radiation dose, and/or addition of chemotherapy. Eleven patients received higher radiation doses. Patients undergoing imaging >8 weeks were more likely to have abnormal results (p = .01). One-year distant metastases-free survival was significantly worse in patients with positive PET/CT scans (61.5% vs 92.7%; p = .01). The estimated positive predictive value (PPV) was 38% for postoperative PET/CT scanning. We demonstrated that 32% of patients have abnormal PET/CT scans resulting in management changes. Patients may benefit from postoperative PET/CT imaging to optimize adjuvant radiation treatment planning. © 2015 Wiley Periodicals, Inc. Head Neck 38: E1285-E1293, 2016. © 2015 Wiley Periodicals, Inc.

Hydrophilic-impermeable modified polyethylene terephthalate for selective endothelialization

NASA Astrophysics Data System (ADS)

Chetouane, D.; Fafet, J. F.; Barbet, R.; Dieval, F.

2017-10-01

The aim of this study was to create a modified polyethylene terephthalate (PET) responding to vascular implants’ requirements, mainly with a surface promoting selective endothelialization. The surface alteration was carried out by hydrophilic functionalization in an alkaline solution with the presence of specific surfactant (TA). The carboxylic groups resulting from this reaction were quantified by colorimetric titration using bleu toluidine O dye (TBO). A single-sided coating process was then optimized to cover the PET surface by micro spherical structures’ polymeric layer. This coating provided to the PET surface high impermeability to the water under a pressure of 120 mmHg and enhanced its hydrophilic property. This spherical topography reduced the adhesion of Mesenchymal Stem Cells (MSC) by 37% and inhibited their proliferation after 3 days by 50%. The hydrophilic functionalized PET (PET-TA) surface decreased the MSC adhesion by 50% and promoted HUVEC attachment with a number twice more important than the number of HUVEC adhered onto non treated-PET.

Integrated PET/MR breast cancer imaging: Attenuation correction and implementation of a 16-channel RF coil

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oehmigen, Mark, E-mail: mark.oehmigen@uni-due.de

Purpose: This study aims to develop, implement, and evaluate a 16-channel radiofrequency (RF) coil for integrated positron emission tomography/magnetic resonance (PET/MR) imaging of breast cancer. The RF coil is designed for optimized MR imaging performance and PET transparency and attenuation correction (AC) is applied for accurate PET quantification. Methods: A 16-channel breast array RF coil was designed for integrated PET/MR hybrid imaging of breast cancer lesions. The RF coil features a lightweight rigid design and is positioned with a spacer at a defined position on the patient table of an integrated PET/MR system. Attenuation correction is performed by generating andmore » applying a dedicated 3D CT-based template attenuation map. Reposition accuracy of the RF coil on the system patient table while using the positioning frame was tested in repeated measurements using MR-visible markers. The MR, PET, and PET/MR imaging performances were systematically evaluated using modular breast phantoms. Attenuation correction of the RF coil was evaluated with difference measurements of the active breast phantoms filled with radiotracer in the PET detector with and without the RF coil in place, serving as a standard of reference measurement. The overall PET/MR imaging performance and PET quantification accuracy of the new 16-channel RF coil and its AC were then evaluated in first clinical examinations on ten patients with local breast cancer. Results: The RF breast array coil provides excellent signal-to-noise ratio and signal homogeneity across the volume of the breast phantoms in MR imaging and visualizes small structures in the phantoms down to 0.4 mm in plane. Difference measurements with PET revealed a global loss and thus attenuation of counts by 13% (mean value across the whole phantom volume) when the RF coil is placed in the PET detector. Local attenuation ranging from 0% in the middle of the phantoms up to 24% was detected in the peripheral regions of the phantoms at positions closer to attenuating hardware structures of the RF coil. The position accuracy of the RF coil on the patient table when using the positioning frame was determined well below 1 mm for all three spatial dimensions. This ensures perfect position match between the RF coil and its three-dimensional attenuation template during the PET data reconstruction process. When applying the CT-based AC of the RF coil, the global attenuation bias was mostly compensated to ±0.5% across the entire breast imaging volume. The patient study revealed high quality MR, PET, and combined PET/MR imaging of breast cancer. Quantitative activity measurements in all 11 breast cancer lesions of the ten patients resulted in increased mean difference values of SUV{sub max} 11.8% (minimum 3.2%; maximum 23.2%) between nonAC images and images when AC of the RF breast coil was applied. This supports the quantitative results of the phantom study as well as successful attenuation correction of the RF coil. Conclusions: A 16-channel breast RF coil was designed for optimized MR imaging performance and PET transparency and was successfully integrated with its dedicated attenuation correction template into a whole-body PET/MR system. Systematic PET/MR imaging evaluation with phantoms and an initial study on patients with breast cancer provided excellent MR and PET image quality and accurate PET quantification.« less

Improvement of organic solar cells by flexible substrate and ITO surface treatments

NASA Astrophysics Data System (ADS)

Cheng, Yuang-Tung; Ho, Jyh-Jier; Wang, Chien-Kun; Lee, William; Lu, Chih-Chiang; Yau, Bao-Shun; Nain, Jhen-Liang; Chang, Shun-Hsyung; Chang, Chiu-Cheng; Wang, Kang L.

2010-10-01

In this paper, surface treatments on polyethylene terephthalate with polymeric hard coating (PET-HC) substrates are described. The effect of the contact angle on the treatment is first investigated. It has been observed that detergent is quite effective in removing organic contamination on the flexible PET-HC substrates. Next, using a DC-reactive magnetron sputter, indium tin oxide (ITO) thin films of 90 nm are grown on a substrate treated by detergent. Then, various ITO surface treatments are made for improving the performance of the finally developed organic solar cells with structure Al/P3HT:PCBM/PEDOT:PSS/ITO/PET. It is found that the parameters of the ITO including resistivity, carrier concentration, transmittance, surface morphology, and work function depended on the surface treatments and significantly influence the solar cell performance. With the optimal conditions for detergent treatment on flexible PET substrates, the ITO film with a resistivity of 5.6 × 10 -4 Ω cm and average optical transmittance of 84.1% in the visible region are obtained. The optimal ITO surface treated by detergent for 5 min and then by UV ozone for 20 min exhibits the best WF value of 5.22 eV. This improves about 8.30% in the WF compared with that of the untreated ITO film. In the case of optimal treatment with the organic photovoltaic device, meanwhile, 36.6% enhancement in short circuit current density ( Jsc) and 92.7% enhancement in conversion efficiency ( η) over the untreated solar cell are obtained.

Motion correction of PET brain images through deconvolution: II. Practical implementation and algorithm optimization

NASA Astrophysics Data System (ADS)

Raghunath, N.; Faber, T. L.; Suryanarayanan, S.; Votaw, J. R.

2009-02-01

Image quality is significantly degraded even by small amounts of patient motion in very high-resolution PET scanners. When patient motion is known, deconvolution methods can be used to correct the reconstructed image and reduce motion blur. This paper describes the implementation and optimization of an iterative deconvolution method that uses an ordered subset approach to make it practical and clinically viable. We performed ten separate FDG PET scans using the Hoffman brain phantom and simultaneously measured its motion using the Polaris Vicra tracking system (Northern Digital Inc., Ontario, Canada). The feasibility and effectiveness of the technique was studied by performing scans with different motion and deconvolution parameters. Deconvolution resulted in visually better images and significant improvement as quantified by the Universal Quality Index (UQI) and contrast measures. Finally, the technique was applied to human studies to demonstrate marked improvement. Thus, the deconvolution technique presented here appears promising as a valid alternative to existing motion correction methods for PET. It has the potential for deblurring an image from any modality if the causative motion is known and its effect can be represented in a system matrix.

Evaluating the purity of a {sup 57}Co flood source by PET

DOE Office of Scientific and Technical Information (OSTI.GOV)

DiFilippo, Frank P., E-mail: difilif@ccf.org

2014-11-01

Purpose: Flood sources of {sup 57}Co are commonly used for quality control of gamma cameras. Flood uniformity may be affected by the contaminants {sup 56}Co and {sup 58}Co, which emit higher energy photons. Although vendors specify a maximum combined {sup 56}Co and {sup 58}Co activity, a convenient test for flood source purity that is feasible in a clinical environment would be desirable. Methods: Both {sup 56}Co and {sup 58}Co emit positrons with branching 19.6% and 14.9%, respectively. As is known from {sup 90}Y imaging, a positron emission tomography (PET) scanner is capable of quantitatively imaging very weak positron emission inmore » a high single-photon background. To evaluate this approach, two {sup 57}Co flood sources were scanned with a clinical PET/CT multiple times over a period of months. The {sup 56}Co and {sup 58}Co activity was clearly visible in the reconstructed PET images. Total impurity activity was quantified from the PET images after background subtraction of prompt gamma coincidences. Results: Time-of-flight PET reconstruction was highly beneficial for accurate image quantification. Repeated measurements of the positron-emitting impurities showed excellent agreement with an exponential decay model. For both flood sources studied, the fit parameters indicated a zero intercept and a decay half-life consistent with a mixture of {sup 56}Co and {sup 58}Co. The total impurity activity at the reference date was estimated to be 0.06% and 0.07% for the two sources, which was consistent with the vendor’s specification of <0.12%. Conclusions: The robustness of the repeated measurements and a thorough analysis of the detector corrections and physics suggest that the accuracy is acceptable and that the technique is feasible. Further work is needed to validate the accuracy of this technique with a calibrated high resolution gamma spectrometer as a gold standard, which was not available for this study, and for other PET detector models.« less

Optimal MRI sequences for 68Ga-PSMA-11 PET/MRI in evaluation of biochemically recurrent prostate cancer.

PubMed

Lake, Spencer T; Greene, Kirsten L; Westphalen, Antonio C; Behr, Spencer C; Zagoria, Ronald; Small, Eric J; Carroll, Peter R; Hope, Thomas A

2017-09-19

PET/MRI can be used for the detection of disease in biochemical recurrence (BCR) patients imaged with 68 Ga-PSMA-11 PET. This study was designed to determine the optimal MRI sequences to localize positive findings on 68 Ga-PSMA-11 PET of patients with BCR after definitive therapy. Fifty-five consecutive prostate cancer patients with BCR imaged with 68 Ga-PSMA-11 3.0T PET/MRI were retrospectively analyzed. Mean PSA was 7.9 ± 12.9 ng/ml, and mean PSA doubling time was 7.1 ± 6.6 months. Detection rates of anatomic correlates for prostate-specific membrane antigen (PSMA)-positive foci were evaluated on small field of view (FOV) T2, T1 post-contrast, and diffusion-weighted images. For prostate bed recurrences, the detection rate of dynamic contrast-enhanced (DCE) imaging for PSMA-positive foci was evaluated. Finally, the detection sensitivity for PSMA-avid foci on 3- and 8-min PET acquisitions was compared. PSMA-positive foci were detected in 89.1% (49/55) of patients evaluated. Small FOV T2 performed best for lymph nodes and detected correlates for all PSMA-avid lymph nodes. DCE imaging performed the best for suspected prostate bed recurrence, detecting correlates for 87.5% (14/16) of PSMA-positive prostate bed foci. The 8-min PET acquisition performed better than the 3-min acquisition for lymph nodes smaller than 1 cm, detecting 100% (57/57) of lymph nodes less than 1 cm, compared to 78.9% (45/57) for the 3-min acquisition. PSMA PET/MRI performed well for the detection of sites of suspected recurrent disease in patients with BCR. Of the MRI sequences obtained for localization, small FOV T2 images detected the greatest proportion of PSMA-positive abdominopelvic lymph nodes and DCE imaging detected the greatest proportion of PSMA-positive prostate bed foci. The 8-min PET acquisition was superior to the 3 min acquisition for detection of small lymph nodes.

A 31-channel MR brain array coil compatible with positron emission tomography.

PubMed

Sander, Christin Y; Keil, Boris; Chonde, Daniel B; Rosen, Bruce R; Catana, Ciprian; Wald, Lawrence L

2015-06-01

Simultaneous acquisition of MR and positron emission tomography (PET) images requires the placement of the MR detection coil inside the PET detector ring where it absorbs and scatters photons. This constraint is the principal barrier to achieving optimum sensitivity on each modality. Here, we present a 31-channel PET-compatible brain array coil with reduced attenuation but improved MR sensitivity. A series of component tests were performed to identify tradeoffs between PET and MR performance. Aspects studied include the remote positioning of preamplifiers, coax size, coil trace size/material, and plastic housing. We then maximized PET performance at minimal cost to MR sensitivity. The coil was evaluated for MR performance (signal to noise ratio [SNR], g-factor) and PET attenuation. The coil design showed an improvement in attenuation by 190% (average) compared with conventional 32-channel arrays, and no loss in MR SNR. Moreover, the 31-channel coil displayed an SNR improvement of 230% (cortical region of interest) compared with a PET-optimized 8-channel array with similar attenuation properties. Implementing attenuation correction of the 31-channel array successfully removed PET artifacts, which were comparable to those of the 8-channel array. The design of the 31-channel PET-compatible coil enables higher sensitivity for PET/MR imaging, paving the way for novel applications in this hybrid-imaging domain. © 2014 Wiley Periodicals, Inc.

Simultaneous whole-body 18F-PSMA-1007-PET/MRI with integrated high-resolution multiparametric imaging of the prostatic fossa for comprehensive oncological staging of patients with prostate cancer: a pilot study.

PubMed

Freitag, Martin T; Kesch, Claudia; Cardinale, Jens; Flechsig, Paul; Floca, Ralf; Eiber, Matthias; Bonekamp, David; Radtke, Jan P; Kratochwil, Clemens; Kopka, Klaus; Hohenfellner, Markus; Stenzinger, Albrecht; Schlemmer, Heinz-Peter; Haberkorn, Uwe; Giesel, Frederik

2018-03-01

The aim of the present study was to explore the clinical feasibility and reproducibility of a comprehensive whole-body 18 F-PSMA-1007-PET/MRI protocol for imaging prostate cancer (PC) patients. Eight patients with high-risk biopsy-proven PC underwent a whole-body PET/MRI (3 h p.i.) including a multi-parametric prostate MRI after 18 F-PSMA-1007-PET/CT (1 h p.i.) which served as reference. Seven patients presented with non-treated PC, whereas one patient presented with biochemical recurrence. SUV mean -quantification was performed using a 3D-isocontour volume-of-interest. Imaging data was consulted for TNM-staging and compared with histopathology. PC was confirmed in 4/7 patients additionally by histopathology after surgery. PET-artifacts, co-registration of pelvic PET/MRI and MRI-data were assessed (PI-RADS 2.0). The examinations were well accepted by patients and comprised 1 h. SUV mean -values between PET/CT (1 h p.i.) and PET/MRI (3 h p.i.) were significantly correlated (p < 0.0001, respectively) and similar to literature of 18 F-PSMA-1007-PET/CT 1 h vs 3 h p.i. The dominant intraprostatic lesion could be detected in all seven patients in both PET and MRI. T2c, T3a, T3b and T4 features were detected complimentarily by PET and MRI in five patients. PET/MRI demonstrated moderate photopenic PET-artifacts surrounding liver and kidneys representing high-contrast areas, no PET-artifacts were observed for PET/CT. Simultaneous PET-readout during prostate MRI achieved optimal co-registration results. The presented 18 F-PSMA-1007-PET/MRI protocol combines efficient whole-body assessment with high-resolution co-registered PET/MRI of the prostatic fossa for comprehensive oncological staging of patients with PC.

Experimental Evaluation of a Deformable Registration Algorithm for Motion Correction in PET-CT Guided Biopsy.

PubMed

Khare, Rahul; Sala, Guillaume; Kinahan, Paul; Esposito, Giuseppe; Banovac, Filip; Cleary, Kevin; Enquobahrie, Andinet

2013-01-01

Positron emission tomography computed tomography (PET-CT) images are increasingly being used for guidance during percutaneous biopsy. However, due to the physics of image acquisition, PET-CT images are susceptible to problems due to respiratory and cardiac motion, leading to inaccurate tumor localization, shape distortion, and attenuation correction. To address these problems, we present a method for motion correction that relies on respiratory gated CT images aligned using a deformable registration algorithm. In this work, we use two deformable registration algorithms and two optimization approaches for registering the CT images obtained over the respiratory cycle. The two algorithms are the BSpline and the symmetric forces Demons registration. In the first optmization approach, CT images at each time point are registered to a single reference time point. In the second approach, deformation maps are obtained to align each CT time point with its adjacent time point. These deformations are then composed to find the deformation with respect to a reference time point. We evaluate these two algorithms and optimization approaches using respiratory gated CT images obtained from 7 patients. Our results show that overall the BSpline registration algorithm with the reference optimization approach gives the best results.

Electronics for a prototype variable field of view PET camera using the PMT-quadrant-sharing detector array

NASA Astrophysics Data System (ADS)

Li, H.; Wong, Wai-Hoi; Zhang, N.; Wang, J.; Uribe, J.; Baghaei, H.; Yokoyama, S.

1999-06-01

Electronics for a prototype high-resolution PET camera with eight position-sensitive detector modules has been developed. Each module has 16 BGO (Bi/sub 4/Ge/sub 3/O/sub 12/) blocks (each block is composed of 49 crystals). The design goals are component and space reduction. The electronics is composed of five parts: front-end analog processing, digital position decoding, fast timing, coincidence processing and master data acquisition. The front-end analog circuit is a zone-based structure (each zone has 3/spl times/3 PMTs). Nine ADCs digitize integration signals of an active zone identified by eight trigger clusters; each cluster is composed of six photomultiplier tubes (PMTs). A trigger corresponding to a gamma ray is sent to a fast timing board to obtain a time-mark, and the nine digitized signals are passed to the position decoding board, where a real block (four PMTs) can be picked out from the zone for position decoding. Lookup tables are used for energy discrimination and to identify the gamma-hit crystal location. The coincidence board opens a 70-ns initial timing window, followed by two 20-ns true/accidental time-mark lookup table windows. The data output from the coincidence board can be acquired either in sinogram mode or in list mode with a Motorola/IRONICS VME-based system.

Global calibration of multi-cameras with non-overlapping fields of view based on photogrammetry and reconfigurable target

NASA Astrophysics Data System (ADS)

Xia, Renbo; Hu, Maobang; Zhao, Jibin; Chen, Songlin; Chen, Yueling

2018-06-01

Multi-camera vision systems are often needed to achieve large-scale and high-precision measurement because these systems have larger fields of view (FOV) than a single camera. Multiple cameras may have no or narrow overlapping FOVs in many applications, which pose a huge challenge to global calibration. This paper presents a global calibration method for multi-cameras without overlapping FOVs based on photogrammetry technology and a reconfigurable target. Firstly, two planar targets are fixed together and made into a long target according to the distance between the two cameras to be calibrated. The relative positions of the two planar targets can be obtained by photogrammetric methods and used as invariant constraints in global calibration. Then, the reprojection errors of target feature points in the two cameras’ coordinate systems are calculated at the same time and optimized by the Levenberg–Marquardt algorithm to find the optimal solution of the transformation matrix between the two cameras. Finally, all the camera coordinate systems are converted to the reference coordinate system in order to achieve global calibration. Experiments show that the proposed method has the advantages of high accuracy (the RMS error is 0.04 mm) and low cost and is especially suitable for on-site calibration.

Mechanical design for the Evryscope: a minute cadence, 10,000-square-degree FoV, gigapixel-scale telescope

NASA Astrophysics Data System (ADS)

Ratzloff, Jeff; Law, Nicholas M.; Fors, Octavi; Wulfken, Philip J.

2015-01-01

We designed, tested, prototyped and built a compact 27-camera robotic telescope that images 10,000 square degrees in 2-minute exposures. We exploit mass produced interline CCD Cameras with Rokinon consumer lenses to economically build a telescope that covers this large part of the sky simultaneously with a good enough pixel sampling to avoid the confusion limit over most of the sky. We developed the initial concept into a 3-d mechanical design with the aid of computer modeling programs. Significant design components include the camera assembly-mounting modules, the hemispherical support structure, and the instrument base structure. We simulated flexure and material stress in each of the three main components, which helped us optimize the rigidity and materials selection, while reducing weight. The camera mounts are CNC aluminum and the support shell is reinforced fiberglass. Other significant project components include optimizing camera locations, camera alignment, thermal analysis, environmental sealing, wind protection, and ease of access to internal components. The Evryscope will be assembled at UNC Chapel Hill and deployed to the CTIO in 2015.

Depth Perception In Remote Stereoscopic Viewing Systems

NASA Technical Reports Server (NTRS)

Diner, Daniel B.; Von Sydow, Marika

1989-01-01

Report describes theoretical and experimental studies of perception of depth by human operators through stereoscopic video systems. Purpose of such studies to optimize dual-camera configurations used to view workspaces of remote manipulators at distances of 1 to 3 m from cameras. According to analysis, static stereoscopic depth distortion decreased, without decreasing stereoscopitc depth resolution, by increasing camera-to-object and intercamera distances and camera focal length. Further predicts dynamic stereoscopic depth distortion reduced by rotating cameras around center of circle passing through point of convergence of viewing axes and first nodal points of two camera lenses.

A LiDAR data-based camera self-calibration method

NASA Astrophysics Data System (ADS)

Xu, Lijun; Feng, Jing; Li, Xiaolu; Chen, Jianjun

2018-07-01

To find the intrinsic parameters of a camera, a LiDAR data-based camera self-calibration method is presented here. Parameters have been estimated using particle swarm optimization (PSO), enhancing the optimal solution of a multivariate cost function. The main procedure of camera intrinsic parameter estimation has three parts, which include extraction and fine matching of interest points in the images, establishment of cost function, based on Kruppa equations and optimization of PSO using LiDAR data as the initialization input. To improve the precision of matching pairs, a new method of maximal information coefficient (MIC) and maximum asymmetry score (MAS) was used to remove false matching pairs based on the RANSAC algorithm. Highly precise matching pairs were used to calculate the fundamental matrix so that the new cost function (deduced from Kruppa equations in terms of the fundamental matrix) was more accurate. The cost function involving four intrinsic parameters was minimized by PSO for the optimal solution. To overcome the issue of optimization pushed to a local optimum, LiDAR data was used to determine the scope of initialization, based on the solution to the P4P problem for camera focal length. To verify the accuracy and robustness of the proposed method, simulations and experiments were implemented and compared with two typical methods. Simulation results indicated that the intrinsic parameters estimated by the proposed method had absolute errors less than 1.0 pixel and relative errors smaller than 0.01%. Based on ground truth obtained from a meter ruler, the distance inversion accuracy in the experiments was smaller than 1.0 cm. Experimental and simulated results demonstrated that the proposed method was highly accurate and robust.

Evaluating [11C]PBR28 PET for Monitoring Gut and Brain Inflammation in a Rat Model of Chemically Induced Colitis.

PubMed

Kurtys, E; Doorduin, J; Eisel, U L M; Dierckx, R A J O; de Vries, E F J

2017-02-01

Ulcerative colitis (UC) is a chronic inflammatory disease of the colon that affects an increasing number of patients. High comorbidity is observed between UC and other diseases in which inflammation may be involved, including brain diseases such as cognitive impairment, mental disorders, anxiety, and depression. To investigate the increased occurrence of these brain diseases in patients with UC, non-invasive methods for monitoring peripheral and central inflammation could be applied. Therefore, the goal of this study is to assess the feasibility of monitoring gut and brain inflammation in a rat model of chemically induced colitis by positron emission tomography (PET) with [ 11 C]PBR28, a tracer targeting the translocator protein (TSPO), which is upregulated when microglia and macrophages are activated. Colitis was induced in rats by intra-rectal injection of 2,4,6-trinitrobenzenesulfonic acid (TNBS). Rats with colitis and healthy control animals were subjected to [ 11 C]PBR28 PET of the abdomen followed by ex vivo biodistribution in order to assess whether inflammation in the gut could be detected. Another group of rats with colitis underwent repetitive [ 11 C]PBR28 PET imaging of the brain to investigate the development of neuroinflammation. Eleven days after TNBS injection, ex vivo biodistribution studies demonstrated increased [ 11 C]PBR28 uptake in the inflamed cecum and colon of rats with colitis as compared to healthy controls, whereas PET imaging did not show any difference between groups at any time. Similarly, repetitive PET imaging of the brain did not reveal any neuroinflammation induced by the TNBS administration in the colon. In contrast, significantly increased [ 11 C]PBR28 uptake in cerebellum could be detected in ex vivo biodistribution studies on day 11. Inflammation in both the gut and the brain of rats with chemically induced colitis was observed by ex vivo biodistribution. However, these effects could not be detected by [ 11 C]PBR28 PET imaging in our colitis model, which is likely due to spill-over effects and insufficient resolution of the PET camera.

Inexpensive position sensitive detector block for dedicated PET cameras using 40-mm diameter PMT in quadrant sharing configuration

NASA Astrophysics Data System (ADS)

Uribe, J.; Aykac, M.; Baghaei, H.; Li, Hongdi; Wang, Yu; Liu, Yaqiang; Wong, V.; Xing, Tao; Ramirez, R.; Wong, Wai-Hoi

2003-06-01

Recent approvals by CMS (HCFA) for reimbursement of positron emission tomography (PET) scans fuels the rapid grow of the PET market, thus creating the need for more affordable dedicated PET scanners. The objective of the work presented here was the development of a BGO position-sensitive block with similar detector area (40 mm /spl times/ 40 mm) and same number of crystals (8 /spl times/ 8) as the block of a commercial BGO PET, using the less expensive photomultiplier quadrant sharing (PQS) technique. This block is coupled to four single-anode 40-mm diameter photomultipliers (PMT) instead of the 19-mm PMT used in a popular commercial BGO PET, and each PMT is shared by four adjacent detector blocks. Potentially, this design needs only 25% of the number of PMT used in the commercial BGO PET. In order not to waste the unused half-row of PMT at the edges of a detector panel/module when the module is made up solely of square blocks, an extended rectangular block has to be developed for the edge-blocks in the module, which maximized the use of the PMT and minimized the gap between modules. Only the extended block needs to be developed to derive the design for all the blocks in the module because the symmetric square block uses the same light-distributing partitions as those along the short side of the extended rectangular block. White-paint masks applied with accurate templates and airbrush were fine-tuned for every pair of adjacent crystals. The experimental block developed in this study provided good crystal-decoding. The composite energy spectrum of all 64 crystals showed a prominent photopeak. The worst crystal sitting in the air space between 4 round PMTs still has 60% of the signal pulse height as the best crystal. The average energy resolution was 21.8% for 511 keV gamma (range 17% - 28.7%) that compared well with the 22% - 44% measured with GE and CTI blocks. The image resolution provided by the PQS blocks is expected to be comparable to that of commercial BGO PETs as similar size crystals were decoded.

Analysis of an Optimized MLOS Tomographic Reconstruction Algorithm and Comparison to the MART Reconstruction Algorithm

NASA Astrophysics Data System (ADS)

La Foy, Roderick; Vlachos, Pavlos

2011-11-01

An optimally designed MLOS tomographic reconstruction algorithm for use in 3D PIV and PTV applications is analyzed. Using a set of optimized reconstruction parameters, the reconstructions produced by the MLOS algorithm are shown to be comparable to reconstructions produced by the MART algorithm for a range of camera geometries, camera numbers, and particle seeding densities. The resultant velocity field error calculated using PIV and PTV algorithms is further minimized by applying both pre and post processing to the reconstructed data sets.

New techniques for positron emission tomography in the study of human neurological disorders

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuhl, D.E.

1993-01-01

This progress report describes accomplishments of four programs. The four programs are entitled (1) Faster,simpler processing of positron-computing precursors: New physicochemical approaches, (2) Novel solid phase reagents and methods to improve radiosynthesis and isotope production, (3) Quantitative evaluation of the extraction of information from PET images, and (4) Optimization of tracer kinetic methods for radioligand studies in PET.

Radiation dosimetry of (68)Ga-PSMA-11 (HBED-CC) and preliminary evaluation of optimal imaging timing.

PubMed

Afshar-Oromieh, Ali; Hetzheim, Henrik; Kübler, Wolfgang; Kratochwil, Clemens; Giesel, Frederik L; Hope, Thomas A; Eder, Matthias; Eisenhut, Michael; Kopka, Klaus; Haberkorn, Uwe

2016-08-01

The clinical introduction of (68)Ga-PSMA-11 ("HBED-CC") ligand targeting the prostate-specific membrane antigen (PSMA) has been regarded as a significant step forward in the diagnosis of prostate cancer (PCa). In this study, we provide human dosimetry and data on optimal timing of PET imaging after injection. Four patients with recurrent PCa were referred for (68)Ga-PSMA-11 PET/CT. Whole-body PET/CTlow-dose scans were conducted at 5 min, and 1, 2, 3, 4 and 5 h after injection of 152-198 MBq (68)Ga-PSMA-11. Organs of moderate to high uptake were used as source organs; their total activity was determined at all measured time points. Time-activity curves were created for each source organ as well as for the remainder. The radiation exposure of a (68)Ga-PSMA-11 PET was identified using the OLINDA-EXM software. In addition, tracer uptake was measured in 16 sites of metastases. The highest tracer uptake was observed in the kidneys, liver, upper large intestine, and the urinary bladder. Mean organ doses were: kidneys 0.262 ± 0.098 mGy/MBq, liver 0.031 ± 0.004 mGy/MBq, upper large intestine 0.054 ± 0.041 mGy/MBq, urinary bladder 0.13 ± 0.059 mGy/MBq. The calculated mean effective dose was 0.023 ± 0.004 mSv/MBq (=0.085 ± 0.015 rem/mCi). Most tumor lesions (n = 16) were visible at 3 h p.i., while at all other time points many were not qualitatively present (10/16 visible at 1 h p.i.). The mean effective dose of a (68)Ga-PSMA-11 PET is 0.023 mSv/MBq. A 3-h delay after injection was optimal timing for (68)Ga-PSMA-11 PET/CT in this patient cohort.

Usefulness of CA125 and their kinetic parameters and positron emission tomography/computed tomography (PET/CT) with fluorodeoxyglucose ([18F] FDG) in the detection of recurrent ovarian cancer levels.

PubMed

Palomar Muñoz, Azahara; Cordero García, José Manuel; Talavera Rubio, Prado; García Vicente, Ana M; González García, Beatriz; Bellón Guardia, María Emiliana; Soriano Castrejón, Ángel; Aranda Aguilar, Enrique

2017-12-21

To assess the usefulness of cancer antigen 125 (CA125) serum levels and kinetic values, velocity (CA125vel) and doubling time (CA125dt), as well as fluorodeoxyglucose ([ 18 F]FDG) positron emission tomography/computed tomography (PET/CT), in the detection of ovarian cancer recurrence. To assess the optimal cut-off for CA125, CA125vel and CA125dt to detect relapse with [ 18 F]FDG-PET/CT. A retrospective analysis was performed of 59 [ 18 F]FDG-PET/CT (48 patients) for suspected recurrence of ovarian cancer. Receiver operating characteristic (ROC) curves were plotted and area-under-the curve (AUC) statistics were computed for CA125, CA125vel and CA125dt. The results obtained in the group with normal and high (>35U/ml) CA125 levels were compared. Forty-four cases of recurrence were diagnosed (7 had CA125 ≤35U/ml), whereas 15 showed no disease. All of them were correctly catalogued by PET/CT. In ROC analysis, the discriminatory power of CA125 was relatively high (AUC 0.835) and the optimal cut-off point to reflect active disease was 23.9U/ml. The ROC analyses for the CA125vel and CA125dt showed an AUC of 0.849 and 0.728, respectively, with an optimal cut-off point of 1.96U/ml/month and 0.76 months, respectively. In patients with normal CA125 and recurrence of ovarian cancer, the CA125vel was significantly higher than in patients without recurrence (p=0.029). [ 18 F]FDG-PET/CT is more accurate than CA125 parameters in the detection of ovarian cancer recurrence. CA125 serum levels are essential; nevertheless, CA125 kinetic values must be considered to detect relapse. Particularly in patients with CA125 within normal values, in which a higher CA125vel is indicative of recurrence. Copyright © 2017 Elsevier España, S.L.U. All rights reserved.

Pretreatment 18F-FDG PET Textural Features in Locally Advanced Non-Small Cell Lung Cancer: Secondary Analysis of ACRIN 6668/RTOG 0235.

PubMed

Ohri, Nitin; Duan, Fenghai; Snyder, Bradley S; Wei, Bo; Machtay, Mitchell; Alavi, Abass; Siegel, Barry A; Johnson, Douglas W; Bradley, Jeffrey D; DeNittis, Albert; Werner-Wasik, Maria; El Naqa, Issam

2016-06-01

In a secondary analysis of American College of Radiology Imaging Network (ACRIN) 6668/RTOG 0235, high pretreatment metabolic tumor volume (MTV) on (18)F-FDG PET was found to be a poor prognostic factor for patients treated with chemoradiotherapy for locally advanced non-small cell lung cancer (NSCLC). Here we utilize the same dataset to explore whether heterogeneity metrics based on PET textural features can provide additional prognostic information. Patients with locally advanced NSCLC underwent (18)F-FDG PET prior to treatment. A gradient-based segmentation tool was used to contour each patient's primary tumor. MTV, maximum SUV, and 43 textural features were extracted for each tumor. To address overfitting and high collinearity among PET features, the least absolute shrinkage and selection operator (LASSO) method was applied to identify features that were independent predictors of overall survival (OS) after adjusting for MTV. Recursive binary partitioning in a conditional inference framework was utilized to identify optimal thresholds. Kaplan-Meier curves and log-rank testing were used to compare outcomes among patient groups. Two hundred one patients met inclusion criteria. The LASSO procedure identified 1 textural feature (SumMean) as an independent predictor of OS. The optimal cutpoint for MTV was 93.3 cm(3), and the optimal SumMean cutpoint for tumors above 93.3 cm(3) was 0.018. This grouped patients into three categories: low tumor MTV (n = 155; median OS, 22.6 mo), high tumor MTV and high SumMean (n = 23; median OS, 20.0 mo), and high tumor MTV and low SumMean (n = 23; median OS, 6.2 mo; log-rank P < 0.001). We have described an appropriate methodology to evaluate the prognostic value of textural PET features in the context of established prognostic factors. We have also identified a promising feature that may have prognostic value in locally advanced NSCLC patients with large tumors who are treated with chemoradiotherapy. Validation studies are warranted. © 2016 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

Pretreatment 18F-FDG PET Textural Features in Locally Advanced Non–Small Cell Lung Cancer: Secondary Analysis of ACRIN 6668/RTOG 0235

PubMed Central

Ohri, Nitin; Duan, Fenghai; Snyder, Bradley S.; Wei, Bo; Machtay, Mitchell; Alavi, Abass; Siegel, Barry A.; Johnson, Douglas W.; Bradley, Jeffrey D.; DeNittis, Albert; Werner-Wasik, Maria; El Naqa, Issam

2016-01-01

In a secondary analysis of American College of Radiology Imaging Network (ACRIN) 6668/RTOG 0235, high pretreatment metabolic tumor volume (MTV) on 18F-FDG PET was found to be a poor prognostic factor for patients treated with chemoradiotherapy for locally advanced non–small cell lung cancer (NSCLC). Here we utilize the same dataset to explore whether heterogeneity metrics based on PET textural features can provide additional prognostic information. Methods Patients with locally advanced NSCLC underwent 18F-FDG PET prior to treatment. A gradient-based segmentation tool was used to contour each patient’s primary tumor. MTV, maximum SUV, and 43 textural features were extracted for each tumor. To address over-fitting and high collinearity among PET features, the least absolute shrinkage and selection operator (LASSO) method was applied to identify features that were independent predictors of overall survival (OS) after adjusting for MTV. Recursive binary partitioning in a conditional inference framework was utilized to identify optimal thresholds. Kaplan–Meier curves and log-rank testing were used to compare outcomes among patient groups. Results Two hundred one patients met inclusion criteria. The LASSO procedure identified 1 textural feature (SumMean) as an independent predictor of OS. The optimal cutpoint for MTV was 93.3 cm3, and the optimal Sum-Mean cutpoint for tumors above 93.3 cm3 was 0.018. This grouped patients into three categories: low tumor MTV (n = 155; median OS, 22.6 mo), high tumor MTV and high SumMean (n = 23; median OS, 20.0 mo), and high tumor MTV and low SumMean (n = 23; median OS, 6.2 mo; log-rank P < 0.001). Conclusion We have described an appropriate methodology to evaluate the prognostic value of textural PET features in the context of established prognostic factors. We have also identified a promising feature that may have prognostic value in locally advanced NSCLC patients with large tumors who are treated with chemoradiotherapy. Validation studies are warranted. PMID:26912429

Material efficiency studies for a Compton camera designed to measure characteristic prompt gamma rays emitted during proton beam radiotherapy

PubMed Central

Robertson, Daniel; Polf, Jerimy C; Peterson, Steve W; Gillin, Michael T; Beddar, Sam

2011-01-01

Prompt gamma rays emitted from biological tissues during proton irradiation carry dosimetric and spectroscopic information that can assist with treatment verification and provide an indication of the biological response of the irradiated tissues. Compton cameras are capable of determining the origin and energy of gamma rays. However, prompt gamma monitoring during proton therapy requires new Compton camera designs that perform well at the high gamma energies produced when tissues are bombarded with therapeutic protons. In this study we optimize the materials and geometry of a three-stage Compton camera for prompt gamma detection and calculate the theoretical efficiency of such a detector. The materials evaluated in this study include germanium, bismuth germanate (BGO), NaI, xenon, silicon and lanthanum bromide (LaBr3). For each material, the dimensions of each detector stage were optimized to produce the maximum number of relevant interactions. These results were used to predict the efficiency of various multi-material cameras. The theoretical detection efficiencies of the most promising multi-material cameras were then calculated for the photons emitted from a tissue-equivalent phantom irradiated by therapeutic proton beams ranging from 50 to 250 MeV. The optimized detector stages had a lateral extent of 10 × 10 cm2 with the thickness of the initial two stages dependent on the detector material. The thickness of the third stage was fixed at 10 cm regardless of material. The most efficient single-material cameras were composed of germanium (3 cm) and BGO (2.5 cm). These cameras exhibited efficiencies of 1.15 × 10−4 and 9.58 × 10−5 per incident proton, respectively. The most efficient multi-material camera design consisted of two initial stages of germanium (3 cm) and a final stage of BGO, resulting in a theoretical efficiency of 1.26 × 10−4 per incident proton. PMID:21508442

Optimization of PET instrumentation for brain activation studies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dahlbom, M.; Cherry, S.R.; Hoffman, E.J.

By performing cerebral blood flow studies with positron emission tomography (PET), and comparing blood flow images of different states of activation, functional mapping of the brain is possible. The ability of current commercial instruments to perform such studies is investigated in this work, based on a comparison of noise equivalent count (NEC) rates. Differences in the NEC performance of the different scanners in conjunction with scanner design parameters, provide insights into the importance of block design (size, dead time, crystal thickness) and overall scanner design (sensitivity and scatter fraction) for optimizing data from activation studies. The newer scanners with removablemore » septa, operating with 3-D acquisition, have much higher sensitivity, but require new methodology for optimized operation. Only by administering multiple low doses (fractionation) of the flow tracer can the high sensitivity be utilized.« less

Design and Optimization of Coin-Shaped Microreactor Chips for PET Radiopharmaceutical Synthesis

PubMed Central

Elizarov, Arkadij M.; van Dam, R. Michael; Shin, Young Shik; Kolb, Hartmuth C.; Padgett, Henry C.; Stout, David; Shu, Jenny; Huang, Jiang; Daridon, Antoine; Heath, James R.

2010-01-01

An integrated elastomeric microfluidic device, with a footprint the size of a postage stamp, has been designed and optimized for multistep radiosynthesis of PET tracers. Methods The unique architecture of the device is centered around a 5-μL coin-shaped reactor, which yields reaction efficiency and speed from a combination of high reagent concentration, pressurized reactions, and rapid heat and mass transfer. Its novel features facilitate mixing, solvent exchange, and product collection. New mixing mechanisms assisted by vacuum, pressure, and chemical reactions are exploited. Results The architecture of the reported reactor is the first that has allowed batch-mode microfluidic devices to produce radiopharmaceuticals of sufficient quality and quantity to be validated by in vivo imaging. Conclusion The reactor has the potential to produce multiple human doses of 18F-FDG; the most impact, however, is expected in the synthesis of PET radiopharmaceuticals that can be made only with low yields by currently available equipment. PMID:20124050

Methodology for quantitative rapid multi-tracer PET tumor characterizations.

PubMed

Kadrmas, Dan J; Hoffman, John M

2013-10-04

Positron emission tomography (PET) can image a wide variety of functional and physiological parameters in vivo using different radiotracers. As more is learned about the molecular basis for disease and treatment, the potential value of molecular imaging for characterizing and monitoring disease status has increased. Characterizing multiple aspects of tumor physiology by imaging multiple PET tracers in a single patient provides additional complementary information, and there is a significant body of literature supporting the potential value of multi-tracer PET imaging in oncology. However, imaging multiple PET tracers in a single patient presents a number of challenges. A number of techniques are under development for rapidly imaging multiple PET tracers in a single scan, where signal-recovery processing algorithms are employed to recover various imaging endpoints for each tracer. Dynamic imaging is generally used with tracer injections staggered in time, and kinetic constraints are utilized to estimate each tracers' contribution to the multi-tracer imaging signal. This article summarizes past and ongoing work in multi-tracer PET tumor imaging, and then organizes and describes the main algorithmic approaches for achieving multi-tracer PET signal-recovery. While significant advances have been made, the complexity of the approach necessitates protocol design, optimization, and testing for each particular tracer combination and application. Rapid multi-tracer PET techniques have great potential for both research and clinical cancer imaging applications, and continued research in this area is warranted.

Methodology for Quantitative Rapid Multi-Tracer PET Tumor Characterizations

PubMed Central

Kadrmas, Dan J.; Hoffman, John M.

2013-01-01

Positron emission tomography (PET) can image a wide variety of functional and physiological parameters in vivo using different radiotracers. As more is learned about the molecular basis for disease and treatment, the potential value of molecular imaging for characterizing and monitoring disease status has increased. Characterizing multiple aspects of tumor physiology by imaging multiple PET tracers in a single patient provides additional complementary information, and there is a significant body of literature supporting the potential value of multi-tracer PET imaging in oncology. However, imaging multiple PET tracers in a single patient presents a number of challenges. A number of techniques are under development for rapidly imaging multiple PET tracers in a single scan, where signal-recovery processing algorithms are employed to recover various imaging endpoints for each tracer. Dynamic imaging is generally used with tracer injections staggered in time, and kinetic constraints are utilized to estimate each tracers' contribution to the multi-tracer imaging signal. This article summarizes past and ongoing work in multi-tracer PET tumor imaging, and then organizes and describes the main algorithmic approaches for achieving multi-tracer PET signal-recovery. While significant advances have been made, the complexity of the approach necessitates protocol design, optimization, and testing for each particular tracer combination and application. Rapid multi-tracer PET techniques have great potential for both research and clinical cancer imaging applications, and continued research in this area is warranted. PMID:24312149

Optimized algorithm for the spatial nonuniformity correction of an imaging system based on a charge-coupled device color camera.

PubMed

de Lasarte, Marta; Pujol, Jaume; Arjona, Montserrat; Vilaseca, Meritxell

2007-01-10

We present an optimized linear algorithm for the spatial nonuniformity correction of a CCD color camera's imaging system and the experimental methodology developed for its implementation. We assess the influence of the algorithm's variables on the quality of the correction, that is, the dark image, the base correction image, and the reference level, and the range of application of the correction using a uniform radiance field provided by an integrator cube. The best spatial nonuniformity correction is achieved by having a nonzero dark image, by using an image with a mean digital level placed in the linear response range of the camera as the base correction image and taking the mean digital level of the image as the reference digital level. The response of the CCD color camera's imaging system to the uniform radiance field shows a high level of spatial uniformity after the optimized algorithm has been applied, which also allows us to achieve a high-quality spatial nonuniformity correction of captured images under different exposure conditions.

[PET/CT: protocol aspects and legal controversies].

PubMed

Gorospe Sarasúa, L; Vicente Bártulos, A; González Gordaliza, C; García Poza, J; Lourido García, D; Jover Díaz, R

2008-01-01

The combination of positron emission tomography (PET) and computed tomography (CT) in a single scanner (PET/CT) allows anatomic and metabolic images to be fused and correlated with a high degree of accuracy; this represents a very important landmark in the history of medicine and especially in the area of diagnostic imaging. Nevertheless, the implementation, startup, and operation of a PET/CT scanner presents particularly interesting challenges, because it involves the integration of two well-established and consolidated techniques (CT and PET, which provide complementary information) that have traditionally been carried out in the context of two different specialties (radiology and nuclear medicine). The rapid diffusion of this new integrated technology raises a series of questions related to the optimal protocols for image acquisition, the supervision of the examinations, image interpretation, and reporting, as well as questions related to the legal competence and responsibility of the specialists involved in a PET/CT study. The objective of this article is to approach these aspects from a constructive perspective and to stimulate the dialog between the specialties of radiology and nuclear medicine, with the aim of maximizing the diagnostic potential of PET/CT and thus of providing better care for patients.

Is choline PET useful for identifying intraprostatic tumour lesions? A literature review.

PubMed

Chan, Joachim; Syndikus, Isabel; Mahmood, Shelan; Bell, Lynn; Vinjamuri, Sobhan

2015-09-01

More than 80% of patients with intermediate-risk or high-risk localized prostate cancer are cured with radiation doses of 74-78 Gy, but high doses increase the risk for late bowel and bladder toxicity among long-term survivors. Dose painting, defined as dose escalation to areas in the prostate containing the tumour, rather than to the whole gland, minimizes dose to normal tissues and hence toxicity. It requires accurate identification of the location and size of these lesions, for which functional MRI is the current gold standard. Many studies have assessed the use of choline PET in staging newly diagnosed patients. This review will discuss important imaging variables affecting the accuracy of choline PET scans, how choline PET contributes to tumour identification and is used in radiotherapy planning and how PET can improve the patient pathway involving prostate radiotherapy. In summary, the available literature shows that the accuracy of choline PET improves with higher tracer doses and delayed imaging (although the optimal uptake time is unclear), and tumour identification by MRI is improved by the addition of PET imaging. We propose future research with prolonged choline uptake time and multiphase imaging, which may further improve accuracy.

The role of FDG-PET in Hodgkin lymphoma

PubMed Central

Hałka, Janusz; Dziuk, Mirosław

2017-01-01

18-fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET)/computed tomography (CT) is currently the most valuable imaging technique in Hodgkin lymphoma. Since its first use in lymphomas in the 1990s, it has become the gold standard in the staging and end-of-treatment remission assessment in patients with Hodgkin lymphoma. The possibility of using early (interim) PET during first-line therapy to evaluate chemosensitivity and thus personalize treatment at this stage holds great promise, and much attention is now being directed toward this goal. With high probability, it is believed that in the near future, the result of interim PET-CT would serve as a compass to optimize treatment. Also the role of PET in pre-transplant assessment is currently evolving. Much controversy surrounds the possibility of detecting relapse after completed treatment with the use of PET in surveillance in the absence of symptoms suggestive of recurrence and the results of published studies are rather discouraging because of low positive predictive value. This review presents current knowledge about the role of 18-FDG-PET/CT imaging at each point of management of patients with Hodgkin lymphoma. PMID:28947879

A generalized reconstruction framework for unconventional PET systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mathews, Aswin John, E-mail: amathews@wustl.edu; Li, Ke; O’Sullivan, Joseph A.

2015-08-15

Purpose: Quantitative estimation of the radionuclide activity concentration in positron emission tomography (PET) requires precise modeling of PET physics. The authors are focused on designing unconventional PET geometries for specific applications. This work reports the creation of a generalized reconstruction framework, capable of reconstructing tomographic PET data for systems that use right cuboidal detector elements positioned at arbitrary geometry using a regular Cartesian grid of image voxels. Methods: The authors report on a variety of design choices and optimization for the creation of the generalized framework. The image reconstruction algorithm is maximum likelihood-expectation–maximization. System geometry can be specified using amore » simple script. Given the geometry, a symmetry seeking algorithm finds existing symmetry in the geometry with respect to the image grid to improve the memory usage/speed. Normalization is approached from a geometry independent perspective. The system matrix is computed using the Siddon’s algorithm and subcrystal approach. The program is parallelized through open multiprocessing and message passing interface libraries. A wide variety of systems can be modeled using the framework. This is made possible by modeling the underlying physics and data correction, while generalizing the geometry dependent features. Results: Application of the framework for three novel PET systems, each designed for a specific application, is presented to demonstrate the robustness of the framework in modeling PET systems of unconventional geometry. Three PET systems of unconventional geometry are studied. (1) Virtual-pinhole half-ring insert integrated into Biograph-40: although the insert device improves image quality over conventional whole-body scanner, the image quality varies depending on the position of the insert and the object. (2) Virtual-pinhole flat-panel insert integrated into Biograph-40: preliminary results from an investigation into a modular flat-panel insert are presented. (3) Plant PET system: a reconfigurable PET system for imaging plants, with resolution of greater than 3.3 mm, is shown. Using the automated symmetry seeking algorithm, the authors achieved a compression ratio of the storage and memory requirement by a factor of approximately 50 for the half-ring and flat-panel systems. For plant PET system, the compression ratio is approximately five. The ratio depends on the level of symmetry that exists in different geometries. Conclusions: This work brings the field closer to arbitrary geometry reconstruction. A generalized reconstruction framework can be used to validate multiple hypotheses and the effort required to investigate each system is reduced. Memory usage/speed can be improved with certain optimizations.« less

A generalized reconstruction framework for unconventional PET systems.

PubMed

Mathews, Aswin John; Li, Ke; Komarov, Sergey; Wang, Qiang; Ravindranath, Bosky; O'Sullivan, Joseph A; Tai, Yuan-Chuan

2015-08-01

Quantitative estimation of the radionuclide activity concentration in positron emission tomography (PET) requires precise modeling of PET physics. The authors are focused on designing unconventional PET geometries for specific applications. This work reports the creation of a generalized reconstruction framework, capable of reconstructing tomographic PET data for systems that use right cuboidal detector elements positioned at arbitrary geometry using a regular Cartesian grid of image voxels. The authors report on a variety of design choices and optimization for the creation of the generalized framework. The image reconstruction algorithm is maximum likelihood-expectation-maximization. System geometry can be specified using a simple script. Given the geometry, a symmetry seeking algorithm finds existing symmetry in the geometry with respect to the image grid to improve the memory usage/speed. Normalization is approached from a geometry independent perspective. The system matrix is computed using the Siddon's algorithm and subcrystal approach. The program is parallelized through open multiprocessing and message passing interface libraries. A wide variety of systems can be modeled using the framework. This is made possible by modeling the underlying physics and data correction, while generalizing the geometry dependent features. Application of the framework for three novel PET systems, each designed for a specific application, is presented to demonstrate the robustness of the framework in modeling PET systems of unconventional geometry. Three PET systems of unconventional geometry are studied. (1) Virtual-pinhole half-ring insert integrated into Biograph-40: although the insert device improves image quality over conventional whole-body scanner, the image quality varies depending on the position of the insert and the object. (2) Virtual-pinhole flat-panel insert integrated into Biograph-40: preliminary results from an investigation into a modular flat-panel insert are presented. (3) Plant PET system: a reconfigurable PET system for imaging plants, with resolution of greater than 3.3 mm, is shown. Using the automated symmetry seeking algorithm, the authors achieved a compression ratio of the storage and memory requirement by a factor of approximately 50 for the half-ring and flat-panel systems. For plant PET system, the compression ratio is approximately five. The ratio depends on the level of symmetry that exists in different geometries. This work brings the field closer to arbitrary geometry reconstruction. A generalized reconstruction framework can be used to validate multiple hypotheses and the effort required to investigate each system is reduced. Memory usage/speed can be improved with certain optimizations.

A generalized reconstruction framework for unconventional PET systems

PubMed Central

Mathews, Aswin John; Li, Ke; Komarov, Sergey; Wang, Qiang; Ravindranath, Bosky; O’Sullivan, Joseph A.; Tai, Yuan-Chuan

2015-01-01

Purpose: Quantitative estimation of the radionuclide activity concentration in positron emission tomography (PET) requires precise modeling of PET physics. The authors are focused on designing unconventional PET geometries for specific applications. This work reports the creation of a generalized reconstruction framework, capable of reconstructing tomographic PET data for systems that use right cuboidal detector elements positioned at arbitrary geometry using a regular Cartesian grid of image voxels. Methods: The authors report on a variety of design choices and optimization for the creation of the generalized framework. The image reconstruction algorithm is maximum likelihood-expectation–maximization. System geometry can be specified using a simple script. Given the geometry, a symmetry seeking algorithm finds existing symmetry in the geometry with respect to the image grid to improve the memory usage/speed. Normalization is approached from a geometry independent perspective. The system matrix is computed using the Siddon’s algorithm and subcrystal approach. The program is parallelized through open multiprocessing and message passing interface libraries. A wide variety of systems can be modeled using the framework. This is made possible by modeling the underlying physics and data correction, while generalizing the geometry dependent features. Results: Application of the framework for three novel PET systems, each designed for a specific application, is presented to demonstrate the robustness of the framework in modeling PET systems of unconventional geometry. Three PET systems of unconventional geometry are studied. (1) Virtual-pinhole half-ring insert integrated into Biograph-40: although the insert device improves image quality over conventional whole-body scanner, the image quality varies depending on the position of the insert and the object. (2) Virtual-pinhole flat-panel insert integrated into Biograph-40: preliminary results from an investigation into a modular flat-panel insert are presented. (3) Plant PET system: a reconfigurable PET system for imaging plants, with resolution of greater than 3.3 mm, is shown. Using the automated symmetry seeking algorithm, the authors achieved a compression ratio of the storage and memory requirement by a factor of approximately 50 for the half-ring and flat-panel systems. For plant PET system, the compression ratio is approximately five. The ratio depends on the level of symmetry that exists in different geometries. Conclusions: This work brings the field closer to arbitrary geometry reconstruction. A generalized reconstruction framework can be used to validate multiple hypotheses and the effort required to investigate each system is reduced. Memory usage/speed can be improved with certain optimizations. PMID:26233187

Efficacy of PET/CT to exclude leiomyoma in patients with lesions suspicious for uterine sarcoma on MRI.

PubMed

Kusunoki, Soshi; Terao, Yasuhisa; Ujihira, Takafumi; Fujino, Kazunari; Kaneda, Hiroshi; Kimura, Miki; Ota, Tsuyoshi; Takeda, Satoru

2017-08-01

To analyze the efficacy of positron emission tomography/computed tomography (PET/CT) for the diagnosis of uterine sarcoma. Thirty-four patients evaluated between January 2010 and March 2015 were retrospectively enrolled. All patients in whom uterine sarcoma was suspected based on contrast-enhanced magnetic resonance imaging (MRI) findings (heterogeneous, high signal intensity on T2-weighted images and/or high intensity on T1-weighted images) underwent PET/CT for further assessment. Patients were divided into 2 groups based on postoperative pathological findings: uterine sarcoma (n = 15) and leiomyoma (n = 19). The maximum standardized uptake value (SUVmax) of all lesions was measured using PET/CT; we calculated the optimal cutoff value for diagnosing sarcoma. The median SUVmax for uterine sarcoma and leiomyoma was 12 and 4.1, respectively; these values were significantly different. An SUVmax of greater than 7.5 was able to exclude leiomyoma with 80.8% sensitivity and 100% specificity (area under the curve, 95.3%). A cutoff SUVmax of 7.5 yields 100% specificity, and a cutoff SUVmax of 4.4 yields a 100% negative predictive value (NPV). The combination of PET/CT and lactate dehydrogenase (LDH) levels had a sensitivity of 86.6%, specificity of 100%, positive predictive value of 100%, and an NPV of 90.4%. No relation between histopathology or International Federation of Gynecology and Obstetrics (FIGO) stage and 18-fluoro-2-deoxy-d-glucose uptake value on PET/CT was seen. The surgical outcome trended toward a correlation with the SUVmax, although this was not statistically significant. In patients with MRI findings consistent with either uterine sarcoma or leiomyoma, PET/CT can decrease the false-positive rate by setting an optimal cutoff SUVmax of 7.5. Using this cutoff can avoid unnecessary surgery. Copyright © 2017. Published by Elsevier B.V.

Rapid Contour-based Segmentation for 18F-FDG PET Imaging of Lung Tumors by Using ITK-SNAP: Comparison to Expert-based Segmentation.

PubMed

Besson, Florent L; Henry, Théophraste; Meyer, Céline; Chevance, Virgile; Roblot, Victoire; Blanchet, Elise; Arnould, Victor; Grimon, Gilles; Chekroun, Malika; Mabille, Laurence; Parent, Florence; Seferian, Andrei; Bulifon, Sophie; Montani, David; Humbert, Marc; Chaumet-Riffaud, Philippe; Lebon, Vincent; Durand, Emmanuel

2018-04-03

Purpose To assess the performance of the ITK-SNAP software for fluorodeoxyglucose (FDG) positron emission tomography (PET) segmentation of complex-shaped lung tumors compared with an optimized, expert-based manual reference standard. Materials and Methods Seventy-six FDG PET images of thoracic lesions were retrospectively segmented by using ITK-SNAP software. Each tumor was manually segmented by six raters to generate an optimized reference standard by using the simultaneous truth and performance level estimate algorithm. Four raters segmented 76 FDG PET images of lung tumors twice by using ITK-SNAP active contour algorithm. Accuracy of ITK-SNAP procedure was assessed by using Dice coefficient and Hausdorff metric. Interrater and intrarater reliability were estimated by using intraclass correlation coefficients of output volumes. Finally, the ITK-SNAP procedure was compared with currently recommended PET tumor delineation methods on the basis of thresholding at 41% volume of interest (VOI; VOI 41 ) and 50% VOI (VOI 50 ) of the tumor's maximal metabolism intensity. Results Accuracy estimates for the ITK-SNAP procedure indicated a Dice coefficient of 0.83 (95% confidence interval: 0.77, 0.89) and a Hausdorff distance of 12.6 mm (95% confidence interval: 9.82, 15.32). Interrater reliability was an intraclass correlation coefficient of 0.94 (95% confidence interval: 0.91, 0.96). The intrarater reliabilities were intraclass correlation coefficients above 0.97. Finally, VOI 41 and VOI 50 accuracy metrics were as follows: Dice coefficient, 0.48 (95% confidence interval: 0.44, 0.51) and 0.34 (95% confidence interval: 0.30, 0.38), respectively, and Hausdorff distance, 25.6 mm (95% confidence interval: 21.7, 31.4) and 31.3 mm (95% confidence interval: 26.8, 38.4), respectively. Conclusion ITK-SNAP is accurate and reliable for active-contour-based segmentation of heterogeneous thoracic PET tumors. ITK-SNAP surpassed the recommended PET methods compared with ground truth manual segmentation. © RSNA, 2018.

Multi-functional carbon microspheres with double shell layers for flame retardant poly (ethylene terephthalate)

NASA Astrophysics Data System (ADS)

Xue, Baoxia; Niu, Mei; Yang, Yongzhen; Bai, Jie; Song, Yinghao; Peng, Yun; Liu, Xuguang

2018-03-01

Carbon microspheres (CMSs) as a core material had been coated by two capsule walls: an inorganic material of magnesium hydroxide (MH) as inner shell layer and an organic material of poly (ethylene terephthalate) (PET) as outer shell layer. MH coating CMSs (MCMSs) were fabricated by liquid phase deposition method, then grafted 3-Aminopropyltriethoxysilane (APTS) to obtain the Si-MCMSs. Microencapsulated Si-MCMSs (PMCMSs) was prepared by in situ polymerization method. Morphology structure, dispersion, flame retardant and other properties of PMCMSs have been investigated. A series of PET blends were prepared by melt compounding. The results showed that MH and PET as two layers were coated on CMSs surface with the optimal thickness of about 70 nm. The PMCMSs owned better dispersion in PET matrix. Compared with MCMSs/PET composites, the mechanical property of PMCMSs/PET composites had significantly increased because of the strong interface binding force between PMCMSs and PET matrix. Moreover, PMCMSs was proved to be an effective flame retardant. For PMCMSs/PET with 2 wt% PMCMSs, the limiting oxygen index (LOI) value increased from 21.0% (pristine PET) to 27.2%, and the peak heat release rate (pk-HRR) decreased from 513.22 kW/m2 to 352.14 kW/m2. The decreased smoke production rate (SPR) and total smoke production (TSP) values demonstrated PMCMSs suppressed the smoke production. The increased Fire performance index (FPI) value illustrated PMCMSs significantly reduced the fire risk of PET. Overall, the two capsular walls endowed the PMCMSs/PET composites with good mechanical and flame-retardant properties.

Optimization of automated large-scale production of [(18)F]fluoroethylcholine for PET prostate cancer imaging.

PubMed

Pascali, Giancarlo; D'Antonio, Luca; Bovone, Paola; Gerundini, Paolo; August, Thorsten

2009-07-01

PET tumor imaging is gaining importance in current clinical practice. FDG-PET is the most utilized approach but suffers from inflammation influences and is not utilizable in prostate cancer detection. Recently, (11)C-choline analogues have been employed successfully in this field of imaging, leading to a growing interest in the utilization of (18)F-labeled analogues: [(18)F]fluoroethylcholine (FEC) has been demonstrated to be promising, especially in prostate cancer imaging. In this work we report an automatic radiosynthesis of this tracer with high yields, short synthesis time and ease of performance, potentially utilizable in routine production sites. We used a Modular Lab system to automatically perform the two-step/one-pot synthesis. In the first step, we labeled ethyleneglycolditosylate obtaining [(18)F]fluoroethyltosylate; in the second step, we performed the coupling of the latter intermediate with neat dimethylethanolamine. The final mixture was purified by means of solid phase extraction; in particular, the product was trapped into a cation-exchange resin and eluted with isotonic saline. The optimized procedure resulted in a non decay corrected yield of 36% and produced a range of 30-45 GBq of product already in injectable form. The product was analyzed for quality control and resulted as pure and sterile; in addition, residual solvents were under the required threshold. In this work, we present an automatic FEC radiosynthesis that has been optimized for routine production. This findings should foster the interest for a wider utilization of this radiomolecule for imaging of prostate cancer with PET, a field for which no gold-standard tracer has yet been validated.

Self-reported fatigue common among optimally treated HIV patients: no correlation with cerebral FDG-PET scanning abnormalities.

PubMed

Andersen, Ase B; Law, Ian; Ostrowski, Sisse R; Lebech, Anne Mette; Høyer-Hansen, Gunilla; Højgaard, Liselotte; Gerstoft, Jan; Ullum, Henrik; Kjaer, Andreas

2006-01-01

It was the aim of this study to determine the prevalence and severity of fatigue among optimally treated HIV patients and to investigate the potential association with systemic inflammation and abnormalities of the distribution of cerebral glucose metabolism. A cohort of HIV patients (n = 95), known to be HIV positive for 5 years, on anti-retroviral therapy for a minimum of 3 years and with CD4 counts above 0.2 x 10(9) cells/l, completed a validated fatigue inventory, and plasma was analysed for pro-inflammatory markers including tumour necrosis factor-alpha, interleukin 6 and soluble urokinase receptor (suPAR) levels. The distribution of the regional cerebral metabolic rate of glucose was measured in a sub-group of patients suffering from severe fatigue (n = 9) and a group with no fatigue (n = 7) using fluorine-18-fluorodeoxyglucose positron emission tomography (FDG-PET) scanning. Fifteen percent suffered from severe fatigue, but no association with pro-inflammatory markers was found. About 50% of the FDG-PET-scanned patients showed minor abnormalities in the relative cerebral metabolic rate of glucose. These abnormalities were not associated with fatigue but tended to correlate with a short HIV history (p = 0.058), a low CD4 nadir (p = 0.082) and elevated tumour necrosis factor-alpha levels (p = 0.074). Fatigue is common among optimally treated HIV patients. FDG-PET-described signs of imminent neurodegeneration among HIV patients who had a low CD4 nadir may illustrate an aspect of HIV neuropathogenicity.

Performance characteristics and relationship of PSA value/kinetics on carbon-11 acetate PET/CT imaging in biochemical relapse of prostate cancer.

PubMed

Almeida, Fabio D; Yen, Chi-Kwan; Scholz, Mark C; Lam, Richard Y; Turner, Jeffrey; Bans, Larry L; Lipson, Robert

2017-01-01

An elevated serum prostate-specific antigen (PSA) level alone cannot distinguish between local-regional recurrences and distant metastases after treatment with curative intent. With available salvage treatments, it has become important to localize the site of recurrence. 11 C-Acetate PET/CT was performed in patients with rising PSA, with statistical analysis of detection rates, sites/location of detection, PSA kinetics and comparison with other tracers (FDG and Choline). Correlation to biopsy, subsequent imaging and PSA response to focal treatment was also performed. 88% (637) of 721 11 C-Acetate PET/CT scans performed were positive. There was a statistically significant difference in PSA values between the positive and negative scans (P < 0.001 for mean difference) with the percentage of positive scans and PSA having a positive correlation. A PSA of 1.09 ng/mL was found to be an optimal cutoff. PSAdT was significantly correlated with a positive scan only when the PSA was < 1.0 ng/mL. For this subgroup, a PSAdT of < 3.8 months appeared significant (P < 0.05) as an optimal cutoff point. 11 C-Acetate PET/CT demonstrates a high detection rate for the site of recurrence/metastasis in biochemical relapsed prostate cancer (88% overall detection rate, PPV 90.8%). This analysis suggests an optimal PSA threshold of > 1.09 ng/mL or a PSAdT of < 3.8 months when the PSA is below 1.0 ng/mL as independent predictors of positive findings.

The electronics system for the LBNL positron emission mammography (PEM) camera

NASA Astrophysics Data System (ADS)

Moses, W. W.; Young, J. W.; Baker, K.; Jones, W.; Lenox, M.; Ho, M. H.; Weng, M.

2001-06-01

Describes the electronics for a high-performance positron emission mammography (PEM) camera. It is based on the electronics for a human brain positron emission tomography (PET) camera (the Siemens/CTI HRRT), modified to use a detector module that incorporates a photodiode (PD) array. An application-specified integrated circuit (ASIC) services the photodetector (PD) array, amplifying its signal and identifying the crystal of interaction. Another ASIC services the photomultiplier tube (PMT), measuring its output and providing a timing signal. Field-programmable gate arrays (FPGAs) and lookup RAMs are used to apply crystal-by-crystal correction factors and measure the energy deposit and the interaction depth (based on the PD/PMT ratio). Additional FPGAs provide event multiplexing, derandomization, coincidence detection, and real-time rebinning. Embedded PC/104 microprocessors provide communication, real-time control, and configure the system. Extensive use of FPGAs make the overall design extremely flexible, allowing many different functions (or design modifications) to be realized without hardware changes. Incorporation of extensive onboard diagnostics, implemented in the FPGAs, is required by the very high level of integration and density achieved by this system.

TU-H-CAMPUS-IeP3-01: Simultaneous PET Restoration and PET/CT Co-Segmentation Using a Variational Method

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, L; Tan, S; Lu, W

Purpose: PET images are usually blurred due to the finite spatial resolution, while CT images suffer from low contrast. Segment a tumor from either a single PET or CT image is thus challenging. To make full use of the complementary information between PET and CT, we propose a novel variational method for simultaneous PET image restoration and PET/CT images co-segmentation. Methods: The proposed model was constructed based on the Γ-convergence approximation of Mumford-Shah (MS) segmentation model for PET/CT co-segmentation. Moreover, a PET de-blur process was integrated into the MS model to improve the segmentation accuracy. An interaction edge constraint termmore » over the two modalities were specially designed to share the complementary information. The energy functional was iteratively optimized using an alternate minimization (AM) algorithm. The performance of the proposed method was validated on ten lung cancer cases and five esophageal cancer cases. The ground truth were manually delineated by an experienced radiation oncologist using the complementary visual features of PET and CT. The segmentation accuracy was evaluated by Dice similarity index (DSI) and volume error (VE). Results: The proposed method achieved an expected restoration result for PET image and satisfactory segmentation results for both PET and CT images. For lung cancer dataset, the average DSI (0.72) increased by 0.17 and 0.40 than single PET and CT segmentation. For esophageal cancer dataset, the average DSI (0.85) increased by 0.07 and 0.43 than single PET and CT segmentation. Conclusion: The proposed method took full advantage of the complementary information from PET and CT images. This work was supported in part by the National Cancer Institute Grants R01CA172638. Shan Tan and Laquan Li were supported in part by the National Natural Science Foundation of China, under Grant Nos. 60971112 and 61375018.« less

MO-G-17A-05: PET Image Deblurring Using Adaptive Dictionary Learning

DOE Office of Scientific and Technical Information (OSTI.GOV)

Valiollahzadeh, S; Clark, J; Mawlawi, O

2014-06-15

Purpose: The aim of this work is to deblur PET images while suppressing Poisson noise effects using adaptive dictionary learning (DL) techniques. Methods: The model that relates a blurred and noisy PET image to the desired image is described as a linear transform y=Hm+n where m is the desired image, H is a blur kernel, n is Poisson noise and y is the blurred image. The approach we follow to recover m involves the sparse representation of y over a learned dictionary, since the image has lots of repeated patterns, edges, textures and smooth regions. The recovery is based onmore » an optimization of a cost function having four major terms: adaptive dictionary learning term, sparsity term, regularization term, and MLEM Poisson noise estimation term. The optimization is solved by a variable splitting method that introduces additional variables. We simulated a 128×128 Hoffman brain PET image (baseline) with varying kernel types and sizes (Gaussian 9×9, σ=5.4mm; Uniform 5×5, σ=2.9mm) with additive Poisson noise (Blurred). Image recovery was performed once when the kernel type was included in the model optimization and once with the model blinded to kernel type. The recovered image was compared to the baseline as well as another recovery algorithm PIDSPLIT+ (Setzer et. al.) by calculating PSNR (Peak SNR) and normalized average differences in pixel intensities (NADPI) of line profiles across the images. Results: For known kernel types, the PSNR of the Gaussian (Uniform) was 28.73 (25.1) and 25.18 (23.4) for DL and PIDSPLIT+ respectively. For blinded deblurring the PSNRs were 25.32 and 22.86 for DL and PIDSPLIT+ respectively. NADPI between baseline and DL, and baseline and blurred for the Gaussian kernel was 2.5 and 10.8 respectively. Conclusion: PET image deblurring using dictionary learning seems to be a good approach to restore image resolution in presence of Poisson noise. GE Health Care.« less

Pre-clinical and Clinical Evaluation of High Resolution, Mobile Gamma Camera and Positron Imaging Devices

DTIC Science & Technology

2009-10-01

Field-of-View, Mobile PET/SPECT System for Bedside Environments: A Dynamic Cardiac Phantom Study using 99mTc and 18F- FDG . Presented at the American...using Tc-99m tracers and viability imaging using F- 18 tracers [3]-[7]. For cardiac F-18 imaging in a bedside environment, the 511 keV SPECT approach...SPECT system may have difficulty imaging subtle myocardial defects with F-18 tracers , but it may effectively image moderate to severe defects. The

SU-G-IeP4-07: Feasibility of Low Dose 18FDG PET in Pediatric Oncology Patients

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, J; Binzel, K; Hall, NC

Purpose: To evaluate and demonstrate the feasibility of low dose FDG PET in pediatric oncology patients using virtual dose reduction as well as true patients PET/CT scans. Methods: Wholebody 18F-FDG PET/CT of 39 clinical pediatric patients (0.16±0.06MBq/kg) were scanned on a Gemini TF 64 system at 75±5 min post FDG injection using 3min/bed. Based on the 180s/bed listmode PET data, subsets of total counts in 120s, 90s, 60s, 30s and 15s per bed position were extracted for PET reconstruction to simulate lower dose PET at 2/3th, 1/2th, 1/3th, 1/6th and 1/12th dose levels. PET/CT scans of Jaszczak PET phantom withmore » 6 hot hollow spheres varying with sizes and contrast ratios were performed (real PET versus simulated PET) to validate the methodology of virtual dose PET simulation. Region of interests (ROIs) were placed on lesions and normal anatomical tissues with quantitative and qualitative assessment performed. Significant lower FDG dose PET/CT of 5 research adolescents were scanned to validate the proposal and low dose PET feasibility. Results: Although all lesions are visible on the 1/12th dose PET, overall PET image quality appears to be influenced in a multi-factorial way. 30%–60% dose reduction from current standard of care FDG PET is recommended to maintain equivalent quality and PET quantification. An optimized BMI-based FDG administration is recommended (from 1.1±0.5 mCi for BMI < 18.5 to 4.8±1.5 mCi for BMI > 30). A linear lowest “Dose-BMI” relationship is given. SUVs from 1/12th to full dose PETs were identified as consistent (R2 = 1.08, 0.99, 1.01, 1.00 and 0.98). No significant variances of count density, SUV and SNR were found across certain dose ranges (p<0.01). Conclusion: Pediatric PET/CT can be performed using current time-of-flight systems at substantially lower PET doses (30–60%) than the standard of care PET/CT without compromising qualitative and quantitative image quality in clinical.« less

Molecular Imaging of Smoke-Induced Changes in Nuclear Factor-Kappa B Expression in Murine Tissues Including the Lung.

PubMed

Syrkina, Olga; Hales, Charles H; Bonab, Ali A; Hamrahi, Victoria; Paul, Kasie; Jung, Walter J; Tompkins, Ronald G; Fischman, Alan J; Carter, Edward A

Many inflammatory responses are mediated by activation of the transcription factor, nuclear factor-kappa B (NF-κB), and a wide variety of human diseases involve abnormal regulation of its expression. In this investigation, we evaluated the effect of smoke inhalation injury on NF-κB expression in lung using two strains of NF-κB reporter mice. Groups of reporter mice with viral thymidine kinase (TK) or "fire fly" luciferase (Luc) genes under control by the NF-κB promoter (TK/NF-κB mice and Luc/NF-κB mice) were subjected to nonlethal smoke inhalation injury. Sham-treated animals served as controls. Twenty-four hours (each animal was injected intravenously with either 9-(4-18F-fluoro-3-[hydroxymethyl]butyl)guanine (FHBG) (~ 1.0 mCi) or luciferin (1.0 mg). One hour later, the TK/NF-κB mice were studied by micro-positron emission tomography (µ-PET) imaging using a Concord P4 µ-PET camera, and the Luc/NF-κB mice were studied by bioluminescence imaging with a charge-coupled device camera. The µ-PET data demonstrated that smoke injury produced massive increases in NF-κB expression (FHBG-standardized uptake value: 3.1 vs 0.0) 24 hours after smoke inhalation, which was reduced 48 hours after smoke inhalation, but still significantly different than the control. Qualitative analysis of the bioluminescence data revealed a remarkably similar effect of burn NF-κB luciferase expression in vivo. Biodistribution studies of FHBG uptake and luciferase activity in lung tissue demonstrated a similar increase 24 hours after injury, which was reduced 48 hours later, but still significantly higher than the sham. The present data with these models providing longitudinal imaging data on the same mouse may prove useful in the examination of the factors producing lung injury by smoke inhalation, as well as the treatment(s) for the damage produced with and without burn injury.

Evaluation of the effect of filter apodization for volume PET imaging using the 3-D RP algorithm

NASA Astrophysics Data System (ADS)

Baghaei, H.; Wong, Wai-Hoi; Li, Hongdi; Uribe, J.; Wang, Yu; Aykac, M.; Liu, Yaqiang; Xing, Tao

2003-02-01

We investigated the influence of filter apodization and cutoff frequency on the image quality of volume positron emission tomography (PET) imaging using the three-dimensional reprojection (3-D RP) algorithm. An important parameter in 3-D RP and other filtered backprojection algorithms is the choice of the filter window function. In this study, the Hann, Hamming, and Butterworth low-pass window functions were investigated. For each window, a range of cutoff frequencies was considered. Projection data were acquired by scanning a uniform cylindrical phantom, a cylindrical phantom containing four small lesion phantoms having diameters of 3, 4, 5, and 6 mm and the 3-D Hoffman brain phantom. All measurements were performed using the high-resolution PET camera developed at the M.D. Anderson Cancer Center (MDAPET), University of Texas, Houston, TX. This prototype camera, which is a multiring scanner with no septa, has an intrinsic transaxial resolution of 2.8 mm. The evaluation was performed by computing the noise level in the reconstructed images of the uniform phantom and the contrast recovery of the 6-mm hot lesion in a warm background and also by visually inspecting images, especially those of the Hoffman brain phantom. For this work, we mainly studied the central slices which are less affected by the incompleteness of the 3-D data. Overall, the Butterworth window offered a better contrast-noise performance over the Hann and Hamming windows. For our high statistics data, for the Hann and Hamming apodization functions a cutoff frequency of 0.6-0.8 of the Nyquist frequency resulted in a reasonable compromise between the contrast recovery and noise level and for the Butterworth window a cutoff frequency of 0.4-0.6 of the Nyquist frequency was a reasonable choice. For the low statistics data, use of lower cutoff frequencies was more appropriate.

Defining optimal tracer activities in pediatric oncologic whole-body 18F-FDG-PET/MRI.

PubMed

Gatidis, Sergios; Schmidt, Holger; la Fougère, Christian; Nikolaou, Konstantin; Schwenzer, Nina F; Schäfer, Jürgen F

2016-12-01

To explore the feasibility of reducing administered tracer activities and to assess optimal activities for combined 18 F-FDG-PET/MRI in pediatric oncology. 30 18 F-FDG-PET/MRI examinations were performed on 24 patients with known or suspected solid tumors (10 girls, 14 boys, age 12 ± 5.6 [1-18] years; PET scan duration: 4 min per bed position). Low-activity PET images were retrospectively simulated from the originally acquired data sets using randomized undersampling of list mode data. PET data of different simulated administered activities (0.25-2.5 MBq/kg body weight) were reconstructed with or without point spread function (PSF) modeling. Mean and maximum standardized uptake values (SUV mean and SUV max ) as well as SUV variation (SUV var ) were measured in physiologic organs and focal FDG-avid lesions. Detectability of organ structures and of focal 18 F-FDG-avid lesions as well as the occurrence of false-positive PET lesions were assessed at different simulated tracer activities. Subjective image quality steadily declined with decreasing tracer activities. Compared to the originally acquired data sets, mean relative deviations of SUV mean and SUV max were below 5 % at 18 F-FDG activities of 1.5 MBq/kg or higher. Over 95 % of anatomic structures and all pathologic focal lesions were detectable at 1.5 MBq/kg 18 F-FDG. Detectability of anatomic structures and focal lesions was significantly improved using PSF. No false-positive focal lesions were observed at tracer activities of 1 MBq/kg 18 F-FDG or higher. Administration of 18 F-FDG activities of 1.5 MBq/kg is, thus, feasible without obvious diagnostic shortcomings, which is equivalent to a dose reduction of more than 50 % compared to current recommendations. Significant reduction in administered 18 F-FDG tracer activities is feasible in pediatric oncologic PET/MRI. Appropriate activities of 18 F-FDG or other tracers for specific clinical questions have to be further established in selected patient populations.

New techniques for positron emission tomography in the study of human neurological disorders. Progress report, June 1990--June 1993

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kuhl, D.E.

1993-06-01

This progress report describes accomplishments of four programs. The four programs are entitled (1) Faster,simpler processing of positron-computing precursors: New physicochemical approaches, (2) Novel solid phase reagents and methods to improve radiosynthesis and isotope production, (3) Quantitative evaluation of the extraction of information from PET images, and (4) Optimization of tracer kinetic methods for radioligand studies in PET.

Multifunctional PSCA antibody fragments for PET and optical prostate cancer imaging

DTIC Science & Technology

2017-10-01

INVESTIGATOR: Anna M. Wu CONTRACTING ORGANIZATION: University of California, Los Angeles Los Angeles, CA 90095-1406 REPORT DATE : October 2017 TYPE OF...cys- minibodies and cys-diabodies) can be labeled with radioisotopes for non-invasive PET imaging for use at multiple points in the prostate cancer...optimize and test multifunctional, F-18, and alternatively labeled fragments Major Task 3. New technologies: alternative site-specific labeling methods

Electron transport in nano-scaled piezoelectronic devices

NASA Astrophysics Data System (ADS)

Jiang, Zhengping; Kuroda, Marcelo A.; Tan, Yaohua; Newns, Dennis M.; Povolotskyi, Michael; Boykin, Timothy B.; Kubis, Tillmann; Klimeck, Gerhard; Martyna, Glenn J.

2013-05-01

The Piezoelectronic Transistor (PET) has been proposed as a post-CMOS device for fast, low-power switching. In this device, the piezoresistive channel is metalized via the expansion of a relaxor piezoelectric element to turn the device on. The mixed-valence compound SmSe is a good choice of PET channel material because of its isostructural pressure-induced continuous metal insulator transition, which is well characterized in bulk single crystals. Prediction and optimization of the performance of a realistic, nano-scaled PET based on SmSe requires the understanding of quantum confinement, tunneling, and the effect of metal interface. In this work, a computationally efficient empirical tight binding (ETB) model is developed for SmSe to study quantum transport in these systems and the scaling limit of PET channel lengths. Modulation of the SmSe band gap under pressure is successfully captured by ETB, and ballistic conductance shows orders of magnitude change under hydrostatic strain, supporting operability of the PET device at nanoscale.

PET-CT and PET-MR in urological cancers other than prostate cancer: An update on state of the art.

PubMed

Razik, Abdul; Das, Chandan Jyoti; Sharma, Sanjay

2018-01-01

Hybrid positron emission tomography with computed tomography (PET/CT) and magnetic resonance imaging (PET/MRI) have enabled the combination of morphologic and functional imaging with the promise of providing better information in guiding therapy. Further advance has been made in the past decade with the development of newer radiotracers and optimization of the technical aspects. We performed a search in PubMed, Scopus, and Google Scholar for peer-reviewed literature concerning the advances and newer developments in the imaging of nonprostate urologic cancers between 2005 and 2017. This review aims at summarizing the current evidence on PET imaging in nonprostate urologic cancers and their impact on the diagnosis, staging, prognostication, response assessment, and restaging of these malignancies. However, much of the evidence is still in infancy and has not been incorporated into routine management or the practice guidelines of National Comprehensive Cancer Network or European Society for Medical Oncology (ESMO).

Prototype design of singles processing unit for the small animal PET

NASA Astrophysics Data System (ADS)

Deng, P.; Zhao, L.; Lu, J.; Li, B.; Dong, R.; Liu, S.; An, Q.

2018-05-01

Position Emission Tomography (PET) is an advanced clinical diagnostic imaging technique for nuclear medicine. Small animal PET is increasingly used for studying the animal model of disease, new drugs and new therapies. A prototype of Singles Processing Unit (SPU) for a small animal PET system was designed to obtain the time, energy, and position information. The energy and position is actually calculated through high precison charge measurement, which is based on amplification, shaping, A/D conversion and area calculation in digital signal processing domian. Analysis and simulations were also conducted to optimize the key parameters in system design. Initial tests indicate that the charge and time precision is better than 3‰ FWHM and 350 ps FWHM respectively, while the position resolution is better than 3.5‰ FWHM. Commination tests of the SPU prototype with the PET detector indicate that the system time precision is better than 2.5 ns, while the flood map and energy spectra concored well with the expected.

Stroma Targeting Nuclear Imaging and Radiopharmaceuticals

PubMed Central

Shetty, Dinesh; Jeong, Jae-Min; Shim, Hyunsuk

2012-01-01

Malignant transformation of tumor accompanies profound changes in the normal neighboring tissue, called tumor stroma. The tumor stroma provides an environment favoring local tumor growth, invasion, and metastatic spreading. Nuclear imaging (PET/SPECT) measures biochemical and physiologic functions in the human body. In oncology, PET/SPECT is particularly useful for differentiating tumors from postsurgical changes or radiation necrosis, distinguishing benign from malignant lesions, identifying the optimal site for biopsy, staging cancers, and monitoring the response to therapy. Indeed, PET/SPECT is a powerful, proven diagnostic imaging modality that displays information unobtainable through other anatomical imaging, such as CT or MRI. When combined with coregistered CT data, [18F]fluorodeoxyglucose ([18F]FDG)-PET is particularly useful. However, [18F]FDG is not a target-specific PET tracer. This paper will review the tumor microenvironment targeting oncologic imaging such as angiogenesis, invasion, hypoxia, growth, and homing, and also therapeutic radiopharmaceuticals to provide a roadmap for additional applications of tumor imaging and therapy. PMID:22685650

18F-fluorodeoxyglucose positron emission tomography/computed tomography-based radiotherapy target volume definition in non-small-cell lung cancer: delineation by radiation oncologists vs. joint outlining with a PET radiologist?

PubMed

Hanna, Gerard G; Carson, Kathryn J; Lynch, Tom; McAleese, Jonathan; Cosgrove, Vivian P; Eakin, Ruth L; Stewart, David P; Zatari, Ashraf; O'Sullivan, Joe M; Hounsell, Alan R

2010-11-15

(18)F-Fluorodeoxyglucose positron emission tomography/computed tomography (PET/CT) has benefits in target volume (TV) definition in radiotherapy treatment planning (RTP) for non-small-cell lung cancer (NSCLC); however, an optimal protocol for TV delineation has not been determined. We investigate volumetric and positional variation in gross tumor volume (GTV) delineation using a planning PET/CT among three radiation oncologists and a PET radiologist. RTP PET/CT scans were performed on 28 NSCLC patients (Stage IA-IIIB) of which 14 patients received prior induction chemotherapy. Three radiation oncologists and one PET radiologist working with a fourth radiation oncologist independently delineated the GTV on CT alone (GTV(CT)) and on fused PET/CT images (GTV(PETCT)). The mean percentage volume change (PVC) between GTV(CT) and GTV(PETCT) for the radiation oncologists and the PVC between GTV(CT) and GTV(PETCT) for the PET radiologist were compared using the Wilcoxon signed-rank test. Concordance index (CI) was used to assess both positional and volume change between GTV(CT) and GTV(PETCT) in a single measurement. For all patients, a significant difference in PVC from GTV(CT) to GTV(PETCT) exists between the radiation oncologist (median, 5.9%), and the PET radiologist (median, -0.4%, p = 0.001). However, no significant difference in median concordance index (comparing GTV(CT) and GTV(FUSED) for individual cases) was observed (PET radiologist = 0.73; radiation oncologists = 0.66; p = 0.088). Percentage volume changes from GTV(CT) to GTV(PETCT) were lower for the PET radiologist than for the radiation oncologists, suggesting a lower impact of PET/CT in TV delineation for the PET radiologist than for the oncologists. Guidelines are needed to standardize the use of PET/CT for TV delineation in RTP. Copyright © 2010 Elsevier Inc. All rights reserved.

FDG-PET Response Prediction in Pediatric Hodgkin's Lymphoma: Impact of Metabolically Defined Tumor Volumes and Individualized SUV Measurements on the Positive Predictive Value.

PubMed

Hussien, Amr Elsayed M; Furth, Christian; Schönberger, Stefan; Hundsdoerfer, Patrick; Steffen, Ingo G; Amthauer, Holger; Müller, Hans-Wilhelm; Hautzel, Hubertus

2015-01-28

In pediatric Hodgkin's lymphoma (pHL) early response-to-therapy prediction is metabolically assessed by (18)F-FDG PET carrying an excellent negative predictive value (NPV) but an impaired positive predictive value (PPV). Aim of this study was to improve the PPV while keeping the optimal NPV. A comparison of different PET data analyses was performed applying individualized standardized uptake values (SUV), PET-derived metabolic tumor volume (MTV) and the product of both parameters, termed total lesion glycolysis (TLG); One-hundred-eight PET datasets (PET1, n = 54; PET2, n = 54) of 54 children were analysed by visual and semi-quantitative means. SUVmax, SUVmean, MTV and TLG were obtained the results of both PETs and the relative change from PET1 to PET2 (Δ in %) were compared for their capability of identifying responders and non-responders using receiver operating characteristics (ROC)-curves. In consideration of individual variations in noise and contrasts levels all parameters were additionally obtained after threshold correction to lean body mass and background; All semi-quantitative SUV estimates obtained at PET2 were significantly superior to the visual PET2 analysis. However, ΔSUVmax revealed the best results (area under the curve, 0.92; p < 0.001; sensitivity 100%; specificity 85.4%; PPV 46.2%; NPV 100%; accuracy, 87.0%) but was not significantly superior to SUVmax-estimation at PET2 and ΔTLGmax. Likewise, the lean body mass and background individualization of the datasets did not impove the results of the ROC analyses; Sophisticated semi-quantitative PET measures in early response assessment of pHL patients do not perform significantly better than the previously proposed ΔSUVmax. All analytical strategies failed to improve the impaired PPV to a clinically acceptable level while preserving the excellent NPV.

Specific recommendations for accurate and direct use of PET-CT in PET guided radiotherapy for head and neck sites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thomas, C. M., E-mail: christopher.thomas@gstt.nhs.uk; Convery, D. J.; Greener, A. G.

2014-04-15

Purpose: To provide specific experience-based guidance and recommendations for centers wishing to develop, validate, and implement an accurate and efficient process for directly using positron emission tomography-computed tomography (PET-CT) for the radiotherapy planning of head and neck cancer patients. Methods: A PET-CT system was modified with hard-top couch, external lasers and radiotherapy immobilization and indexing devices and was subject to a commissioning and quality assurance program. PET-CT imaging protocols were developed specifically for radiotherapy planning and the image quality and pathway tested using phantoms and five patients recruited into an in-house study. Security and accuracy of data transfer was testedmore » throughout the whole data pathway. The patient pathway was fully established and tested ready for implementation in a PET-guided dose-escalation trial for head and neck cancer patients. Results: Couch deflection was greater than for departmental CT simulator machines. An area of high attenuation in the couch generated image artifacts and adjustments were made accordingly. Using newly developed protocols CT image quality was suitable to maintain delineation and treatment accuracy. Upon transfer of data to the treatment planning system a half pixel offset between PET and CT was observed and corrected. By taking this into account, PET to CT alignment accuracy was maintained below 1 mm in all systems in the data pathway. Transfer of structures delineated in the PET fusion software to the radiotherapy treatment planning system was validated. Conclusions: A method to perform direct PET-guided radiotherapy planning was successfully validated and specific recommendations were developed to assist other centers. Of major concern is ensuring that the quality of PET and CT data is appropriate for radiotherapy treatment planning and on-treatment verification. Couch movements can be compromised, bore-size can be a limitation for certain immobilization techniques, laser positioning may affect setup accuracy and couch deflection may be greater than scanners dedicated to radiotherapy. The full set of departmental commissioning and routine quality assurance tests applied to radiotherapy CT simulators must be carried out on the PET-CT scanner. CT image quality must be optimized for radiotherapy planning whilst understanding that the appearance will differ between scanners and may affect delineation. PET-CT quality assurance schedules will need to be added to and modified to incorporate radiotherapy quality assurance. Methods of working for radiotherapy and PET staff will change to take into account considerations of both parties. PET to CT alignment must be subject to quality control on a loaded and unloaded couch preferably using a suitable emission phantom, and tested throughout the whole data pathway. Data integrity must be tested throughout the whole pathway and a system included to verify that delineated structures are transferred correctly. Excellent multidisciplinary team communication and working is vital, and key staff members on both sides should be specifically dedicated to the project. Patient pathway should be clearly devised to optimize patient care and the resources of all departments. Recruitment of a cohort of patients into a methodology study is valuable to test the quality assurance methods and pathway.« less

Feasibility and robustness of dose painting by numbers in proton therapy with contour-driven plan optimization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Barragán, A. M., E-mail: ana.barragan@uclouvain.be; Differding, S.; Lee, J. A.

Purpose: To prove the ability of protons to reproduce a dose gradient that matches a dose painting by numbers (DPBN) prescription in the presence of setup and range errors, by using contours and structure-based optimization in a commercial treatment planning system. Methods: For two patients with head and neck cancer, voxel-by-voxel prescription to the target volume (GTV{sub PET}) was calculated from {sup 18}FDG-PET images and approximated with several discrete prescription subcontours. Treatments were planned with proton pencil beam scanning. In order to determine the optimal plan parameters to approach the DPBN prescription, the effects of the scanning pattern, number ofmore » fields, number of subcontours, and use of range shifter were separately tested on each patient. Different constant scanning grids (i.e., spot spacing = Δx = Δy = 3.5, 4, and 5 mm) and uniform energy layer separation [4 and 5 mm WED (water equivalent distance)] were analyzed versus a dynamic and automatic selection of the spots grid. The number of subcontours was increased from 3 to 11 while the number of beams was set to 3, 5, or 7. Conventional PTV-based and robust clinical target volumes (CTV)-based optimization strategies were considered and their robustness against range and setup errors assessed. Because of the nonuniform prescription, ensuring robustness for coverage of GTV{sub PET} inevitably leads to overdosing, which was compared for both optimization schemes. Results: The optimal number of subcontours ranged from 5 to 7 for both patients. All considered scanning grids achieved accurate dose painting (1% average difference between the prescribed and planned doses). PTV-based plans led to nonrobust target coverage while robust-optimized plans improved it considerably (differences between worst-case CTV dose and the clinical constraint was up to 3 Gy for PTV-based plans and did not exceed 1 Gy for robust CTV-based plans). Also, only 15% of the points in the GTV{sub PET} (worst case) were above 5% of DPBN prescription for robust-optimized plans, while they were more than 50% for PTV plans. Low dose to organs at risk (OARs) could be achieved for both PTV and robust-optimized plans. Conclusions: DPBN in proton therapy is feasible with the use of a sufficient number subcontours, automatically generated scanning patterns, and no more than three beams are needed. Robust optimization ensured the required target coverage and minimal overdosing, while PTV-approach led to nonrobust plans with excessive overdose. Low dose to OARs can be achieved even in the presence of a high-dose escalation as in DPBN.« less

Use of radioactive substances in diagnosis and treatment of neuroendocrine tumors

PubMed Central

Kjaer, Andreas; Knigge, Ulrich

2015-01-01

Abstract Radionuclides are needed both for nuclear medicine imaging as well as for peptide-receptor radionuclide therapy (PRRT) of neuroendocrine tumors (NET). Imaging is important in the initial diagnostic work-up and for staging NETs. In therapy planning, somatostatin receptor imaging (SRI) is used when treatment is targeted at the somatostatin receptors as with the use of somatostatin analogues or PRRT. SRI with gamma camera technique using the tracer 111In-DTPA-octreotide has for many years been the backbone of nuclear imaging of NETs. However, increasingly PET tracers for SRI are now used. 68Ga-DOTATATE, 68Ga-DOTATOC and 68Ga-DOTANOC are the three most often used PET tracers. They perform better than SPECT tracers and should be preferred. FDG-PET is well suited for visualization of most of the somatostatin receptor-negative tumors prognostic in NET patients. Also 11C-5-HTP, 18F-DOPA and 123I-MIBG may be used in NET. However, with FDG-PET and somatostatin receptor PET at hand we see limited necessity of other tracers. PRRT is an important tool in the treatment of advanced NETs causing complete or partial response in 20% and minor response or tumor stabilization in 60% with response duration of up to 3 years. Grade 3–4 kidney or bone marrow toxicity is seen in 1.5% and 9.5%, respectively, but are completely or partly reversible in most patients. 177Lu-DOTATATE seems to have less toxicity than 90Y-DOTATOC. However, until now only retrospective, non-randomized studies have been performed and the role of PRRT in treatment of NETs remains to be established. PMID:25959100

Use of radioactive substances in diagnosis and treatment of neuroendocrine tumors.

PubMed

Kjaer, Andreas; Knigge, Ulrich

2015-06-01

Radionuclides are needed both for nuclear medicine imaging as well as for peptide-receptor radionuclide therapy (PRRT) of neuroendocrine tumors (NET). Imaging is important in the initial diagnostic work-up and for staging NETs. In therapy planning, somatostatin receptor imaging (SRI) is used when treatment is targeted at the somatostatin receptors as with the use of somatostatin analogues or PRRT. SRI with gamma camera technique using the tracer (111)In-DTPA-octreotide has for many years been the backbone of nuclear imaging of NETs. However, increasingly PET tracers for SRI are now used. (68)Ga-DOTATATE, (68)Ga-DOTATOC and (68)Ga-DOTANOC are the three most often used PET tracers. They perform better than SPECT tracers and should be preferred. FDG-PET is well suited for visualization of most of the somatostatin receptor-negative tumors prognostic in NET patients. Also (11)C-5-HTP, (18)F-DOPA and (123)I-MIBG may be used in NET. However, with FDG-PET and somatostatin receptor PET at hand we see limited necessity of other tracers. PRRT is an important tool in the treatment of advanced NETs causing complete or partial response in 20% and minor response or tumor stabilization in 60% with response duration of up to 3 years. Grade 3-4 kidney or bone marrow toxicity is seen in 1.5% and 9.5%, respectively, but are completely or partly reversible in most patients. (177)Lu-DOTATATE seems to have less toxicity than (90)Y-DOTATOC. However, until now only retrospective, non-randomized studies have been performed and the role of PRRT in treatment of NETs remains to be established.

Fluorescence-enhanced optical tomography and nuclear imaging system for small animals

NASA Astrophysics Data System (ADS)

Tan, I.-Chih; Lu, Yujie; Darne, Chinmay; Rasmussen, John C.; Zhu, Banghe; Azhdarinia, Ali; Yan, Shikui; Smith, Anne M.; Sevick-Muraca, Eva M.

2012-03-01

Near-infrared (NIR) fluorescence is an alternative modality for molecular imaging that has been demonstrated in animals and recently in humans. Fluorescence-enhanced optical tomography (FEOT) using continuous wave or frequency domain photon migration techniques could be used to provide quantitative molecular imaging in vivo if it could be validated against "gold-standard," nuclear imaging modalities, using dual-labeled imaging agents. Unfortunately, developed FEOT systems are not suitable for incorporation with CT/PET/SPECT scanners because they utilize benchtop devices and require a large footprint. In this work, we developed a miniaturized fluorescence imaging system installed in the gantry of the Siemens Inveon PET/CT scanner to enable NIR transillumination measurements. The system consists of a CCD camera equipped with NIR sensitive intensifier, a diode laser controlled by a single board compact controller, a 2-axis galvanometer, and RF circuit modules for homodyne detection of the phase and amplitude of fluorescence signals. The performance of the FEOT system was tested and characterized. A mouse-shaped solid phantom of uniform optical properties with a fluorescent inclusion was scanned using CT, and NIR fluorescence images at several projections were collected. The method of high-order approximation to the radioactive transfer equation was then used to reconstruct the optical images. Dual-labeled agents were also used on a tumor bearing mouse to validate the results of the FEOT against PET/CT image. The results showed that the location of the fluorophore obtained from the FEOT matches the location of tumor obtained from the PET/CT images. Besides validation of FEOT, this hybrid system could allow multimodal molecular imaging (FEOT/PET/CT) for small animal imaging.

Positron emission tomography: a novel technique for investigating the biodistribution and transport of nanoparticles.

PubMed

Palko, Heather A; Fung, Jennifer Y; Louie, Angelique Y

2010-07-01

Particulate matter (PM) has been associated with serious health effects within but also outside of the pulmonary system. Therefore, there is great interest in studying the biodistribution of PM after delivery to the lung to correlate sites of extrapulmonary particle accumulation and abnormal conditions known to be associated with PM exposure. Traditional PM tracking studies have introduced nanoparticles to animal models or humans and have determined the biodistribution with gamma counting, gamma camera, and inductively coupled plasma mass spectrometry (ICP-MS). The authors here demonstrate that positron emission tomography (PET) is a powerful tool that can be employed to visualize the deposition and track the fate of nanoparticles in the mouse model. In these studies, approximately 100-nm polystyrene nanoparticles were labeled with the positron emitter 64Cu bound by the chelator (S)-2-(4-isothiocyanatobenzyl)-1,4,7,10-tetraazacyclododecane-tetraacetic acid (p-SCN-Bn-DOTA). The labeled nanoparticles were instilled intratracheally into C57BL/6 mice; the initial deposition and biodistribution through 48 h was determined by PET imaging. In addition to static imaging, dynamic imaging was performed in the Sprague-Dawley rat model to demonstrate that PET can capture particle movement in pseudo-time-lapse videos. Particle deposition and clearance was clearly identified by PET, and the same animals could be imaged repeatedly without any adverse effects from anesthesia. PET has the potential to require many fewer animals than traditional methods while still providing quantitative results. In addition, the initial deposition pattern in each animal can be accurately determined and the same animal monitored over time so that data interpretation is not clouded by variations in initial deposition profiles.

dAcquisition setting optimization and quantitative imaging for 124I studies with the Inveon microPET-CT system.

PubMed

Anizan, Nadège; Carlier, Thomas; Hindorf, Cecilia; Barbet, Jacques; Bardiès, Manuel

2012-02-13

Noninvasive multimodality imaging is essential for preclinical evaluation of the biodistribution and pharmacokinetics of radionuclide therapy and for monitoring tumor response. Imaging with nonstandard positron-emission tomography [PET] isotopes such as 124I is promising in that context but requires accurate activity quantification. The decay scheme of 124I implies an optimization of both acquisition settings and correction processing. The PET scanner investigated in this study was the Inveon PET/CT system dedicated to small animal imaging. The noise equivalent count rate [NECR], the scatter fraction [SF], and the gamma-prompt fraction [GF] were used to determine the best acquisition parameters for mouse- and rat-sized phantoms filled with 124I. An image-quality phantom as specified by the National Electrical Manufacturers Association NU 4-2008 protocol was acquired and reconstructed with two-dimensional filtered back projection, 2D ordered-subset expectation maximization [2DOSEM], and 3DOSEM with maximum a posteriori [3DOSEM/MAP] algorithms, with and without attenuation correction, scatter correction, and gamma-prompt correction (weighted uniform distribution subtraction). Optimal energy windows were established for the rat phantom (390 to 550 keV) and the mouse phantom (400 to 590 keV) by combining the NECR, SF, and GF results. The coincidence time window had no significant impact regarding the NECR curve variation. Activity concentration of 124I measured in the uniform region of an image-quality phantom was underestimated by 9.9% for the 3DOSEM/MAP algorithm with attenuation and scatter corrections, and by 23% with the gamma-prompt correction. Attenuation, scatter, and gamma-prompt corrections decreased the residual signal in the cold insert. The optimal energy windows were chosen with the NECR, SF, and GF evaluation. Nevertheless, an image quality and an activity quantification assessment were required to establish the most suitable reconstruction algorithm and corrections for 124I small animal imaging.

SU-E-T-182: Feasibility of Dose Painting by Numbers in Proton Therapy with Contour-Driven Plan Optimization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Montero, A Barragan; Differding, S; Lee, J

Purpose: The work aims to 1) prove the feasibility of dose painting by numbers (DPBN) in proton therapy with usual contour-driven plan optimization and 2) compare the achieved plan quality to that of rotational IMRT. Methods: For two patients with head and neck cancers, voxel-by-voxel prescription to the target volume (PTV-PET) was calculated from {sup 18} FDG-PET images and converted to contour-based prescription by defining several sub-contours. Treatments were planned with RayStation (RaySearch Laboratories, Sweden) and proton pencil beam scanning modality. In order to determine the optimal plan parameters to approach the DPBN prescription, the effect of the number ofmore » fields, number of sub-contours and use of range shifter were tested separately on each patient. The number of sub-contours were increased from 3 to 11 while the number of fields were set to 3, 5, 7 and 9. Treatment plans were also optimized on two rotational IMRT systems (TomoTherapy and Varian RapidArc) using previously published guidelines. Results: For both patients, more than 99% of the PTV-PET received at least 95% of the prescribed dose while less than 1% of the PTV-PET received more than 105%, which demonstrates the feasibility of the treatment. Neither the use of a range shifter nor the increase of the number of fields had a significant influence on PTV coverage. Plan quality increased when increasing number of fields up to 7 or 9 and slightly decreased for a bigger number of sub-contours. Good OAR sparing is achieved while keeping high plan quality. Finally, proton therapy achieved significantly better plan quality than rotational IMRT. Conclusion: Voxel-by-voxel prescriptions can be approximated accurately in proton therapy using a contour-driven optimization. Target coverage is nearly insensitive to the number of fields and the use of a range shifter. Finally, plan quality assessment confirmed the superiority of proton therapy compared to rotational IMRT.« less

[Optimization of radiotherapy planning for non-small cell lung cancer (NSCLC) using 18FDG-PET].

PubMed

Schmidt, S; Nestle, U; Walter, K; Licht, N; Ukena, D; Schnabel, K; Kirsch, C M

2002-10-01

In recent years, FDG-PET examinations have become more important for problems in oncology, especially in staging of bronchogenic carcinoma. In the retrospective study presented here, the influence of PET on the planning of radiotherapy for patients with non-small-cell lung cancer (NSCLC) was investigated. The study involved 39 patients with NSCLC who had been examined by PET for staging. They received radiotherapy on the basis of the anterior/posterior portals including the primary tumour and the mediastinum planned according to CT- and bronchoscopic findings. The results of the PET examination were not considered in initial radiotherapy planning. The portals were retrospectively redefined on the basis of FDG uptake considering the size and localization of the primary tumour; and FDG activities outside the mediastinal part of the portals. In 15 out of 39 patients, the CT/PET-planned portals differed from the CT-planned ones. In most causes (n = 12) the CT/PET field was smaller than the CT field. The median geometric field size of the portals was 179 cm2, after redefinition using PET 166 cm2. In 20 patients with disturbed ventilation caused by the tumour (atelectasis, dystelectosis), a correction of the portal was suggested significantly more frequently than in the other patients (p = 0.03). Our results demonstrate the synergism of topographical (CT) and metabolic (FDG-PET) information, which could be helpful in planning radiotherapy of bronchial carcinoma, especially for patients with disturbed ventilation.

A simplified radiometabolite analysis procedure for PET radioligands using a solid phase extraction with micellar medium.

PubMed

Nakao, Ryuji; Halldin, Christer

2013-07-01

A solid phase extraction method has been developed for simple and high-speed direct determination of PET radioligands in plasma. This methodology makes use of a micellar medium and a solid-phase extraction cartridge for displacement of plasma protein bound radioligand and separation of PET radioligands from their radiometabolites without significant preparation. The plasma samples taken from monkey or human during PET measurements were mixed with a micellar eluent containing an anionic surfactant sodium dodecyl sulphate and loaded onto SPE cartridges. The amount of radioactivity corresponding to parent radioligand (retained on the cartridge) and its radioactive metabolites (eluted with micellar eluent) was measured. Under the optimized conditions, excellent separation of target PET radioligands from their radiometabolites was achieved with a single elution and short run-time of 1 min. This method was successfully applied to study the metabolism for (11)C-labelled radioligands in human or monkey plasma. The amount of parent PET radioligands estimated by micellar solid phase extraction strongly corresponded with that determined by radio-LC. The improved throughput permitted the analysis of a large number of plasma samples (up to 13 samples per one PET study) for accurate estimation of metabolite-corrected input function during quantitative PET imaging studies. Solid phase extraction together with micellar medium is fast, sensitive and easy to use, and therefore it is an attractive alternative method to determine relative composition of PET radioligands in plasma. Copyright © 2013 Elsevier Inc. All rights reserved.

Automatic anatomy recognition in whole-body PET/CT images

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Huiqian; Udupa, Jayaram K., E-mail: jay@mail.med.upenn.edu; Odhner, Dewey

Purpose: Whole-body positron emission tomography/computed tomography (PET/CT) has become a standard method of imaging patients with various disease conditions, especially cancer. Body-wide accurate quantification of disease burden in PET/CT images is important for characterizing lesions, staging disease, prognosticating patient outcome, planning treatment, and evaluating disease response to therapeutic interventions. However, body-wide anatomy recognition in PET/CT is a critical first step for accurately and automatically quantifying disease body-wide, body-region-wise, and organwise. This latter process, however, has remained a challenge due to the lower quality of the anatomic information portrayed in the CT component of this imaging modality and the paucity ofmore » anatomic details in the PET component. In this paper, the authors demonstrate the adaptation of a recently developed automatic anatomy recognition (AAR) methodology [Udupa et al., “Body-wide hierarchical fuzzy modeling, recognition, and delineation of anatomy in medical images,” Med. Image Anal. 18, 752–771 (2014)] to PET/CT images. Their goal was to test what level of object localization accuracy can be achieved on PET/CT compared to that achieved on diagnostic CT images. Methods: The authors advance the AAR approach in this work in three fronts: (i) from body-region-wise treatment in the work of Udupa et al. to whole body; (ii) from the use of image intensity in optimal object recognition in the work of Udupa et al. to intensity plus object-specific texture properties, and (iii) from the intramodality model-building-recognition strategy to the intermodality approach. The whole-body approach allows consideration of relationships among objects in different body regions, which was previously not possible. Consideration of object texture allows generalizing the previous optimal threshold-based fuzzy model recognition method from intensity images to any derived fuzzy membership image, and in the process, to bring performance to the level achieved on diagnostic CT and MR images in body-region-wise approaches. The intermodality approach fosters the use of already existing fuzzy models, previously created from diagnostic CT images, on PET/CT and other derived images, thus truly separating the modality-independent object assembly anatomy from modality-specific tissue property portrayal in the image. Results: Key ways of combining the above three basic ideas lead them to 15 different strategies for recognizing objects in PET/CT images. Utilizing 50 diagnostic CT image data sets from the thoracic and abdominal body regions and 16 whole-body PET/CT image data sets, the authors compare the recognition performance among these 15 strategies on 18 objects from the thorax, abdomen, and pelvis in object localization error and size estimation error. Particularly on texture membership images, object localization is within three voxels on whole-body low-dose CT images and 2 voxels on body-region-wise low-dose images of known true locations. Surprisingly, even on direct body-region-wise PET images, localization error within 3 voxels seems possible. Conclusions: The previous body-region-wise approach can be extended to whole-body torso with similar object localization performance. Combined use of image texture and intensity property yields the best object localization accuracy. In both body-region-wise and whole-body approaches, recognition performance on low-dose CT images reaches levels previously achieved on diagnostic CT images. The best object recognition strategy varies among objects; the proposed framework however allows employing a strategy that is optimal for each object.« less

Characterization and engineering of a plastic-degrading aromatic polyesterase

PubMed Central

Austin, Harry P.; Allen, Mark D.; Rorrer, Nicholas A.; Kearns, Fiona L.; Silveira, Rodrigo L.; Pollard, Benjamin C.; Dominick, Graham; El Omari, Kamel; Mykhaylyk, Vitaliy; Michener, William E.; Amore, Antonella; Skaf, Munir S.; Crowley, Michael F.; Thorne, Alan W.; Johnson, Christopher W.; Woodcock, H. Lee

2018-01-01

Poly(ethylene terephthalate) (PET) is one of the most abundantly produced synthetic polymers and is accumulating in the environment at a staggering rate as discarded packaging and textiles. The properties that make PET so useful also endow it with an alarming resistance to biodegradation, likely lasting centuries in the environment. Our collective reliance on PET and other plastics means that this buildup will continue unless solutions are found. Recently, a newly discovered bacterium, Ideonella sakaiensis 201-F6, was shown to exhibit the rare ability to grow on PET as a major carbon and energy source. Central to its PET biodegradation capability is a secreted PETase (PET-digesting enzyme). Here, we present a 0.92 Å resolution X-ray crystal structure of PETase, which reveals features common to both cutinases and lipases. PETase retains the ancestral α/β-hydrolase fold but exhibits a more open active-site cleft than homologous cutinases. By narrowing the binding cleft via mutation of two active-site residues to conserved amino acids in cutinases, we surprisingly observe improved PET degradation, suggesting that PETase is not fully optimized for crystalline PET degradation, despite presumably evolving in a PET-rich environment. Additionally, we show that PETase degrades another semiaromatic polyester, polyethylene-2,5-furandicarboxylate (PEF), which is an emerging, bioderived PET replacement with improved barrier properties. In contrast, PETase does not degrade aliphatic polyesters, suggesting that it is generally an aromatic polyesterase. These findings suggest that additional protein engineering to increase PETase performance is realistic and highlight the need for further developments of structure/activity relationships for biodegradation of synthetic polyesters. PMID:29666242

Characterization and engineering of a plastic-degrading aromatic polyesterase

DOE Office of Scientific and Technical Information (OSTI.GOV)

Austin, Harry P.; Allen, Mark D.; Donohoe, Bryon S.

Poly(ethylene terephthalate) (PET) is one of the most abundantly produced synthetic polymers and is accumulating in the environment at a staggering rate as discarded packaging and textiles. The properties that make PET so useful also endow it with an alarming resistance to biodegradation, likely lasting centuries in the environment. Our collective reliance on PET and other plastics means that this buildup will continue unless solutions are found. Recently, a newly discovered bacterium, Ideonella sakaiensis 201-F6, was shown to exhibit the rare ability to grow on PET as a major carbon and energy source. Central to its PET biodegradation capability ismore » a secreted PETase (PET-digesting enzyme). Here, we present a 0.92 A resolution X-ray crystal structure of PETase, which reveals features common to both cutinases and lipases. PETase retains the ancestral a/..beta..-hydrolase fold but exhibits a more open active-site cleft than homologous cutinases. By narrowing the binding cleft via mutation of two active-site residues to conserved amino acids in cutinases, we surprisingly observe improved PET degradation, suggesting that PETase is not fully optimized for crystalline PET degradation, despite presumably evolving in a PET-rich environment. Additionally, we show that PETase degrades another semiaromatic polyester, polyethylene-2,5-furandicarboxylate (PEF), which is an emerging, bioderived PET replacement with improved barrier properties. In contrast, PETase does not degrade aliphatic polyesters, suggesting that it is generally an aromatic polyesterase. These findings suggest that additional protein engineering to increase PETase performance is realistic and highlight the need for further developments of structure/activity relationships for biodegradation of synthetic polyesters.« less

Characterization and engineering of a plastic-degrading aromatic polyesterase

DOE PAGES

Austin, Harry P.; Allen, Mark D.; Donohoe, Bryon S.; ...

2018-04-17

Poly(ethylene terephthalate) (PET) is one of the most abundantly produced synthetic polymers and is accumulating in the environment at a staggering rate as discarded packaging and textiles. The properties that make PET so useful also endow it with an alarming resistance to biodegradation, likely lasting centuries in the environment. Our collective reliance on PET and other plastics means that this buildup will continue unless solutions are found. Recently, a newly discovered bacterium, Ideonella sakaiensis 201-F6, was shown to exhibit the rare ability to grow on PET as a major carbon and energy source. Central to its PET biodegradation capability ismore » a secreted PETase (PET-digesting enzyme). Here, we present a 0.92 A resolution X-ray crystal structure of PETase, which reveals features common to both cutinases and lipases. PETase retains the ancestral a/..beta..-hydrolase fold but exhibits a more open active-site cleft than homologous cutinases. By narrowing the binding cleft via mutation of two active-site residues to conserved amino acids in cutinases, we surprisingly observe improved PET degradation, suggesting that PETase is not fully optimized for crystalline PET degradation, despite presumably evolving in a PET-rich environment. Additionally, we show that PETase degrades another semiaromatic polyester, polyethylene-2,5-furandicarboxylate (PEF), which is an emerging, bioderived PET replacement with improved barrier properties. In contrast, PETase does not degrade aliphatic polyesters, suggesting that it is generally an aromatic polyesterase. These findings suggest that additional protein engineering to increase PETase performance is realistic and highlight the need for further developments of structure/activity relationships for biodegradation of synthetic polyesters.« less

Ringfield lithographic camera

DOEpatents

Sweatt, William C.

1998-01-01

A projection lithography camera is presented with a wide ringfield optimized so as to make efficient use of extreme ultraviolet radiation from a large area radiation source (e.g., D.sub.source .apprxeq.0.5 mm). The camera comprises four aspheric mirrors optically arranged on a common axis of symmetry with an increased etendue for the camera system. The camera includes an aperture stop that is accessible through a plurality of partial aperture stops to synthesize the theoretical aperture stop. Radiation from a mask is focused to form a reduced image on a wafer, relative to the mask, by reflection from the four aspheric mirrors.

Optimization of yttrium-90 PET for simultaneous PET/MR imaging: A phantom study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eldib, Mootaz

2016-08-15

Purpose: Positron emission tomography (PET) imaging of yttrium-90 in the liver post radioembolization has been shown useful for personalized dosimetry calculations and evaluation of extrahepatic deposition. The purpose of this study was to quantify the benefits of several MR-based data correction approaches offered by using a combined PET/MR system to improve Y-90 PET imaging. In particular, the feasibility of motion and partial volume corrections were investigated in a controlled phantom study. Methods: The ACR phantom was filled with an initial concentration of 8 GBq of Y-90 solution resulting in a contrast of 10:1 between the hot cylinders and the background.more » Y-90 PET motion correction through motion estimates from MR navigators was evaluated by using a custom-built motion stage that simulated realistic amplitudes of respiration-induced liver motion. Finally, the feasibility of an MR-based partial volume correction method was evaluated using a wavelet decomposition approach. Results: Motion resulted in a large (∼40%) loss of contrast recovery for the 8 mm cylinder in the phantom, but was corrected for after MR-based motion correction was applied. Partial volume correction improved contrast recovery by 13% for the 8 mm cylinder. Conclusions: MR-based data correction improves Y-90 PET imaging on simultaneous PET/MR systems. Assessment of these methods must be studied further in the clinical setting.« less

A Digital Preclinical PET/MRI Insert and Initial Results.

PubMed

Weissler, Bjoern; Gebhardt, Pierre; Dueppenbecker, Peter M; Wehner, Jakob; Schug, David; Lerche, Christoph W; Goldschmidt, Benjamin; Salomon, Andre; Verel, Iris; Heijman, Edwin; Perkuhn, Michael; Heberling, Dirk; Botnar, Rene M; Kiessling, Fabian; Schulz, Volkmar

2015-11-01

Combining Positron Emission Tomography (PET) with Magnetic Resonance Imaging (MRI) results in a promising hybrid molecular imaging modality as it unifies the high sensitivity of PET for molecular and cellular processes with the functional and anatomical information from MRI. Digital Silicon Photomultipliers (dSiPMs) are the digital evolution in scintillation light detector technology and promise high PET SNR. DSiPMs from Philips Digital Photon Counting (PDPC) were used to develop a preclinical PET/RF gantry with 1-mm scintillation crystal pitch as an insert for clinical MRI scanners. With three exchangeable RF coils, the hybrid field of view has a maximum size of 160 mm × 96.6 mm (transaxial × axial). 0.1 ppm volume-root-mean-square B 0-homogeneity is kept within a spherical diameter of 96 mm (automatic volume shimming). Depending on the coil, MRI SNR is decreased by 13% or 5% by the PET system. PET count rates, energy resolution of 12.6% FWHM, and spatial resolution of 0.73 mm (3) (isometric volume resolution at isocenter) are not affected by applied MRI sequences. PET time resolution of 565 ps (FWHM) degraded by 6 ps during an EPI sequence. Timing-optimized settings yielded 260 ps time resolution. PET and MR images of a hot-rod phantom show no visible differences when the other modality was in operation and both resolve 0.8-mm rods. Versatility of the insert is shown by successfully combining multi-nuclei MRI ((1)H/(19)F) with simultaneously measured PET ((18)F-FDG). A longitudinal study of a tumor-bearing mouse verifies the operability, stability, and in vivo capabilities of the system. Cardiac- and respiratory-gated PET/MRI motion-capturing (CINE) images of the mouse heart demonstrate the advantage of simultaneous acquisition for temporal and spatial image registration.

Real-Time Counting People in Crowded Areas by Using Local Empirical Templates and Density Ratios

NASA Astrophysics Data System (ADS)

Hung, Dao-Huu; Hsu, Gee-Sern; Chung, Sheng-Luen; Saito, Hideo

In this paper, a fast and automated method of counting pedestrians in crowded areas is proposed along with three contributions. We firstly propose Local Empirical Templates (LET), which are able to outline the foregrounds, typically made by single pedestrians in a scene. LET are extracted by clustering foregrounds of single pedestrians with similar features in silhouettes. This process is done automatically for unknown scenes. Secondly, comparing the size of group foreground made by a group of pedestrians to that of appropriate LET captured in the same image patch with the group foreground produces the density ratio. Because of the local scale normalization between sizes, the density ratio appears to have a bound closely related to the number of pedestrians who induce the group foreground. Finally, to extract the bounds of density ratios for groups of different number of pedestrians, we propose a 3D human models based simulation in which camera viewpoints and pedestrians' proximity are easily manipulated. We collect hundreds of typical occluded-people patterns with distinct degrees of human proximity and under a variety of camera viewpoints. Distributions of density ratios with respect to the number of pedestrians are built based on the computed density ratios of these patterns for extracting density ratio bounds. The simulation is performed in the offline learning phase to extract the bounds from the distributions, which are used to count pedestrians in online settings. We reveal that the bounds seem to be invariant to camera viewpoints and humans' proximity. The performance of our proposed method is evaluated with our collected videos and PETS 2009's datasets. For our collected videos with the resolution of 320x240, our method runs in real-time with good accuracy and frame rate of around 30 fps, and consumes a small amount of computing resources. For PETS 2009's datasets, our proposed method achieves competitive results with other methods tested on the same datasets [1], [2].

Role of PET/CT for precision medicine in lung cancer: perspective of the Society of Nuclear Medicine and Molecular Imaging.

PubMed

Greenspan, Bennett S

2017-12-01

This article discusses the role of PET/CT in contributing to precision medicine in lung cancer, and provides the perspective of the Society of Nuclear Medicine and Molecular Imaging (SNMMI) on this process. The mission and vision of SNMMI are listed, along with the guidance provided by SNMMI to promote best practice in precision medicine. Basic principles of PET/CT are presented. An overview of the use of PET/CT imaging in lung cancer is discussed. In lung cancer patients, PET/CT is vitally important for optimal patient management. PET/CT is essential in determining staging and re-staging of disease, detecting recurrent or residual disease, evaluating response to therapy, and providing prognostic information. PET/CT is also critically important in radiation therapy planning by determining the extent of active disease, including an assessment of functional tumor volume. The current approach in tumor imaging is a significant advance over conventional imaging. However, recent advances suggest that therapeutic response criteria in the near future will be based on metabolic characteristics and will include the evaluation of biologic characteristics of tumors to further enhance the effectiveness of precision medicine in lung cancer, producing improved patient outcomes with less morbidity.

Development and Design of Next-Generation Head-Mounted Ambulatory Microdose Positron-Emission Tomography (AM-PET) System.

PubMed

Melroy, Samantha; Bauer, Christopher; McHugh, Matthew; Carden, Garret; Stolin, Alexander; Majewski, Stan; Brefczynski-Lewis, Julie; Wuest, Thorsten

2017-05-19

Several applications exist for a whole brain positron-emission tomography (PET) brain imager designed as a portable unit that can be worn on a patient's head. Enabled by improvements in detector technology, a lightweight, high performance device would allow PET brain imaging in different environments and during behavioral tasks. Such a wearable system that allows the subjects to move their heads and walk-the Ambulatory Microdose PET (AM-PET)-is currently under development. This imager will be helpful for testing subjects performing selected activities such as gestures, virtual reality activities and walking. The need for this type of lightweight mobile device has led to the construction of a proof of concept portable head-worn unit that uses twelve silicon photomultiplier (SiPM) PET module sensors built into a small ring which fits around the head. This paper is focused on the engineering design of mechanical support aspects of the AM-PET project, both of the current device as well as of the coming next-generation devices. The goal of this work is to optimize design of the scanner and its mechanics to improve comfort for the subject by reducing the effect of weight, and to enable diversification of its applications amongst different research activities.

Development and Design of Next-Generation Head-Mounted Ambulatory Microdose Positron-Emission Tomography (AM-PET) System

PubMed Central

Melroy, Samantha; Bauer, Christopher; McHugh, Matthew; Carden, Garret; Stolin, Alexander; Majewski, Stan; Brefczynski-Lewis, Julie; Wuest, Thorsten

2017-01-01

Several applications exist for a whole brain positron-emission tomography (PET) brain imager designed as a portable unit that can be worn on a patient’s head. Enabled by improvements in detector technology, a lightweight, high performance device would allow PET brain imaging in different environments and during behavioral tasks. Such a wearable system that allows the subjects to move their heads and walk—the Ambulatory Microdose PET (AM-PET)—is currently under development. This imager will be helpful for testing subjects performing selected activities such as gestures, virtual reality activities and walking. The need for this type of lightweight mobile device has led to the construction of a proof of concept portable head-worn unit that uses twelve silicon photomultiplier (SiPM) PET module sensors built into a small ring which fits around the head. This paper is focused on the engineering design of mechanical support aspects of the AM-PET project, both of the current device as well as of the coming next-generation devices. The goal of this work is to optimize design of the scanner and its mechanics to improve comfort for the subject by reducing the effect of weight, and to enable diversification of its applications amongst different research activities. PMID:28534848

Quantitative assessment of atherosclerotic plaques on (18)F-FDG PET/MRI: comparison with a PET/CT hybrid system.

PubMed

Li, Xiang; Heber, Daniel; Rausch, Ivo; Beitzke, Dietrich; Mayerhoefer, Marius E; Rasul, Sazan; Kreissl, Michael; Mitthauser, Markus; Wadsak, Wolfgang; Hartenbach, Markus; Haug, Alexander; Zhang, Xiaoli; Loewe, Christian; Beyer, Thomas; Hacker, Marcus

2016-07-01

PET with (18)F-FDG has the potential to assess vascular macrophage metabolism. (18)F-FDG is most often used in combination with contrast-enhanced CT to localize increased metabolism to specific arterial lesions. Novel (18)F-FDG PET/MRI hybrid imaging shows high potential for the combined evaluation of atherosclerotic plaques, due to the superior morphological conspicuity of plaque lesions. The purpose of this study was to evaluate the reliability and accuracy of (18)F-FDG PET/MRI uptake quantification compared to PET/CT as a reference standard in patients with carotid atherosclerotic plaques. The study group comprised 34 consecutive oncological patients with carotid plaques who underwent both PET/CT and PET/MRI with (18)F-FDG on the same day. The presence of atherosclerotic plaques was confirmed by 3 T MRI scans. Maximum standardized uptake values (SUVmax) for carotid plaque lesions and the average SUV of the blood pool within the adjacent internal jugular vein were determined and target-to-blood ratios (TBRs, plaque to blood pool) were calculated. Atherosclerotic lesions with maximum colocalized focal FDG uptake were assessed in each patient. SUVmax values of carotid plaque lesions were significantly lower on PET/MRI than on PET/CT (2.3 ± 0.6 vs. 3.1 ± 0.6; P < 0.01), but were significantly correlated between PET/CT and PET/MRI (Spearman's r = 0.67, P < 0.01). In contrast, TBRmax values of plaque lesions were similar on PET/MRI and on PET/CT (2.2 ± 0.3 vs. 2.2 ± 0.3; P = 0.4), and again were significantly correlated between PET/MRI and PET/CT (Spearman's r = 0.73, P < 0.01). Considering the increasing trend in SUVmax and TBRmax values from early to delayed imaging time-points on PET/CT and PET/MRI, respectively, with continuous clearance of radioactivity from the blood, a slight underestimation of TBRmax values may also be expected with PET/MRI compared with PET/CT. SUVmax and TBRmax values are widely accepted reference parameters for estimation of the radioactivity of atherosclerotic plaques on PET/CT. However, due to a systematic underestimation of SUVmax and TBRmax with PET/MRI, the optimal cut-off values indicating the presence of inflamed plaque tissue need to be newly defined for PET/MRI.

Comparison of five cluster validity indices performance in brain [18 F]FET-PET image segmentation using k-means.

PubMed

Abualhaj, Bedor; Weng, Guoyang; Ong, Melissa; Attarwala, Ali Asgar; Molina, Flavia; Büsing, Karen; Glatting, Gerhard

2017-01-01

Dynamic [ 18 F]fluoro-ethyl-L-tyrosine positron emission tomography ([ 18 F]FET-PET) is used to identify tumor lesions for radiotherapy treatment planning, to differentiate glioma recurrence from radiation necrosis and to classify gliomas grading. To segment different regions in the brain k-means cluster analysis can be used. The main disadvantage of k-means is that the number of clusters must be pre-defined. In this study, we therefore compared different cluster validity indices for automated and reproducible determination of the optimal number of clusters based on the dynamic PET data. The k-means algorithm was applied to dynamic [ 18 F]FET-PET images of 8 patients. Akaike information criterion (AIC), WB, I, modified Dunn's and Silhouette indices were compared on their ability to determine the optimal number of clusters based on requirements for an adequate cluster validity index. To check the reproducibility of k-means, the coefficients of variation CVs of the objective function values OFVs (sum of squared Euclidean distances within each cluster) were calculated using 100 random centroid initialization replications RCI 100 for 2 to 50 clusters. k-means was performed independently on three neighboring slices containing tumor for each patient to investigate the stability of the optimal number of clusters within them. To check the independence of the validity indices on the number of voxels, cluster analysis was applied after duplication of a slice selected from each patient. CVs of index values were calculated at the optimal number of clusters using RCI 100 to investigate the reproducibility of the validity indices. To check if the indices have a single extremum, visual inspection was performed on the replication with minimum OFV from RCI 100 . The maximum CV of OFVs was 2.7 × 10 -2 from all patients. The optimal number of clusters given by modified Dunn's and Silhouette indices was 2 or 3 leading to a very poor segmentation. WB and I indices suggested in median 5, [range 4-6] and 4, [range 3-6] clusters, respectively. For WB, I, modified Dunn's and Silhouette validity indices the suggested optimal number of clusters was not affected by the number of the voxels. The maximum coefficient of variation of WB, I, modified Dunn's, and Silhouette validity indices were 3 × 10 -2 , 1, 2 × 10 -1 and 3 × 10 -3 , respectively. WB-index showed a single global maximum, whereas the other indices showed also local extrema. From the investigated cluster validity indices, the WB-index is best suited for automated determination of the optimal number of clusters for [ 18 F]FET-PET brain images for the investigated image reconstruction algorithm and the used scanner: it yields meaningful results allowing better differentiation of tissues with higher number of clusters, it is simple, reproducible and has an unique global minimum. © 2016 American Association of Physicists in Medicine.

Real-time optimizations for integrated smart network camera

NASA Astrophysics Data System (ADS)

Desurmont, Xavier; Lienard, Bruno; Meessen, Jerome; Delaigle, Jean-Francois

2005-02-01

We present an integrated real-time smart network camera. This system is composed of an image sensor, an embedded PC based electronic card for image processing and some network capabilities. The application detects events of interest in visual scenes, highlights alarms and computes statistics. The system also produces meta-data information that could be shared between other cameras in a network. We describe the requirements of such a system and then show how the design of the system is optimized to process and compress video in real-time. Indeed, typical video-surveillance algorithms as background differencing, tracking and event detection should be highly optimized and simplified to be used in this hardware. To have a good adequation between hardware and software in this light embedded system, the software management is written on top of the java based middle-ware specification established by the OSGi alliance. We can integrate easily software and hardware in complex environments thanks to the Java Real-Time specification for the virtual machine and some network and service oriented java specifications (like RMI and Jini). Finally, we will report some outcomes and typical case studies of such a camera like counter-flow detection.

Improving the color fidelity of cameras for advanced television systems

NASA Astrophysics Data System (ADS)

Kollarits, Richard V.; Gibbon, David C.

1992-08-01

In this paper we compare the accuracy of the color information obtained from television cameras using three and five wavelength bands. This comparison is based on real digital camera data. The cameras are treated as colorimeters whose characteristics are not linked to that of the display. The color matrices for both cameras were obtained by identical optimization procedures that minimized the color error The color error for the five band camera is 2. 5 times smaller than that obtained from the three band camera. Visual comparison of color matches on a characterized color monitor indicate that the five band camera is capable of color measurements that produce no significant visual error on the display. Because the outputs from the five band camera are reduced to the normal three channels conventionally used for display there need be no increase in signal handling complexity outside the camera. Likewise it is possible to construct a five band camera using only three sensors as in conventional cameras. The principal drawback of the five band camera is the reduction in effective camera sensitivity by about 3/4 of an I stop. 1.

SU-C-9A-06: The Impact of CT Image Used for Attenuation Correction in 4D-PET

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cui, Y; Bowsher, J; Yan, S

2014-06-01

Purpose: To evaluate the appropriateness of using 3D non-gated CT image for attenuation correction (AC) in a 4D-PET (gated PET) imaging protocol used in radiotherapy treatment planning simulation. Methods: The 4D-PET imaging protocol in a Siemens PET/CT simulator (Biograph mCT, Siemens Medical Solutions, Hoffman Estates, IL) was evaluated. CIRS Dynamic Thorax Phantom (CIRS Inc., Norfolk, VA) with a moving glass sphere (8 mL) in the middle of its thorax portion was used in the experiments. The glass was filled with {sup 18}F-FDG and was in a longitudinal motion derived from a real patient breathing pattern. Varian RPM system (Varian Medicalmore » Systems, Palo Alto, CA) was used for respiratory gating. Both phase-gating and amplitude-gating methods were tested. The clinical imaging protocol was modified to use three different CT images for AC in 4D-PET reconstruction: first is to use a single-phase CT image to mimic actual clinical protocol (single-CT-PET); second is to use the average intensity projection CT (AveIP-CT) derived from 4D-CT scanning (AveIP-CT-PET); third is to use 4D-CT image to do the phase-matched AC (phase-matching- PET). Maximum SUV (SUVmax) and volume of the moving target (glass sphere) with threshold of 40% SUVmax were calculated for comparison between 4D-PET images derived with different AC methods. Results: The SUVmax varied 7.3%±6.9% over the breathing cycle in single-CT-PET, compared to 2.5%±2.8% in AveIP-CT-PET and 1.3%±1.2% in phasematching PET. The SUVmax in single-CT-PET differed by up to 15% from those in phase-matching-PET. The target volumes measured from single- CT-PET images also presented variations up to 10% among different phases of 4D PET in both phase-gating and amplitude-gating experiments. Conclusion: Attenuation correction using non-gated CT in 4D-PET imaging is not optimal process for quantitative analysis. Clinical 4D-PET imaging protocols should consider phase-matched 4D-CT image if available to achieve better accuracy.« less

Photography in Dermatologic Surgery: Selection of an Appropriate Lighting Solution for a Particular Clinical Application.

PubMed

Chen, Brian R; Poon, Emily; Alam, Murad

2018-01-01

Lighting is an important component of consistent, high-quality dermatologic photography. There are different types of lighting solutions available. To evaluate currently available lighting equipment and methods suitable for procedural dermatology. Overhead lighting, built-in camera flashes, external flash units, studio strobes, and light-emitting diode (LED) light panels were evaluated with regard to their utility for dermatologic surgeons. A set of ideal lighting characteristics was used to examine the capabilities and limitations of each type of lighting solution. Recommendations regarding lighting solutions and optimal usage configurations were made in terms of the context of the clinical environment and the purpose of the image. Overhead lighting may be a convenient option for general documentation. An on-camera lighting solution using a built-in camera flash or a camera-mounted external flash unit provides portability and consistent lighting with minimal training. An off-camera lighting solution with studio strobes, external flash units, or LED light panels provides versatility and even lighting with minimal shadows and glare. The selection of an optimal lighting solution is contingent on practical considerations and the purpose of the image.

Optimization of Rb-82 PET acquisition and reconstruction protocols for myocardial perfusion defect detection

NASA Astrophysics Data System (ADS)

Tang, Jing; Rahmim, Arman; Lautamäki, Riikka; Lodge, Martin A.; Bengel, Frank M.; Tsui, Benjamin M. W.

2009-05-01

The purpose of this study is to optimize the dynamic Rb-82 cardiac PET acquisition and reconstruction protocols for maximum myocardial perfusion defect detection using realistic simulation data and task-based evaluation. Time activity curves (TACs) of different organs under both rest and stress conditions were extracted from dynamic Rb-82 PET images of five normal patients. Combined SimSET-GATE Monte Carlo simulation was used to generate nearly noise-free cardiac PET data from a time series of 3D NCAT phantoms with organ activities modeling different pre-scan delay times (PDTs) and total acquisition times (TATs). Poisson noise was added to the nearly noise-free projections and the OS-EM algorithm was applied to generate noisy reconstructed images. The channelized Hotelling observer (CHO) with 32× 32 spatial templates corresponding to four octave-wide frequency channels was used to evaluate the images. The area under the ROC curve (AUC) was calculated from the CHO rating data as an index for image quality in terms of myocardial perfusion defect detection. The 0.5 cycle cm-1 Butterworth post-filtering on OS-EM (with 21 subsets) reconstructed images generates the highest AUC values while those from iteration numbers 1 to 4 do not show different AUC values. The optimized PDTs for both rest and stress conditions are found to be close to the cross points of the left ventricular chamber and myocardium TACs, which may promote an individualized PDT for patient data processing and image reconstruction. Shortening the TATs for <~3 min from the clinically employed acquisition time does not affect the myocardial perfusion defect detection significantly for both rest and stress studies.

Optimization of a miniature short-wavelength infrared objective optics of a short-wavelength infrared to visible upconversion layer attached to a mobile-devices visible camera

NASA Astrophysics Data System (ADS)

Kadosh, Itai; Sarusi, Gabby

2017-10-01

The use of dual cameras in parallax in order to detect and create 3-D images in mobile devices has been increasing over the last few years. We propose a concept where the second camera will be operating in the short-wavelength infrared (SWIR-1300 to 1800 nm) and thus have night vision capability while preserving most of the other advantages of dual cameras in terms of depth and 3-D capabilities. In order to maintain commonality of the two cameras, we propose to attach to one of the cameras a SWIR to visible upconversion layer that will convert the SWIR image into a visible image. For this purpose, the fore optics (the objective lenses) should be redesigned for the SWIR spectral range and the additional upconversion layer, whose thickness is <1 μm. Such layer should be attached in close proximity to the mobile device visible range camera sensor (the CMOS sensor). This paper presents such a SWIR objective optical design and optimization that is formed and fit mechanically to the visible objective design but with different lenses in order to maintain the commonality and as a proof-of-concept. Such a SWIR objective design is very challenging since it requires mimicking the original visible mobile camera lenses' sizes and the mechanical housing, so we can adhere to the visible optical and mechanical design. We present in depth a feasibility study and the overall optical system performance of such a SWIR mobile-device camera fore optics design.

Auto-converging stereo cameras for 3D robotic tele-operation

NASA Astrophysics Data System (ADS)

Edmondson, Richard; Aycock, Todd; Chenault, David

2012-06-01

Polaris Sensor Technologies has developed a Stereovision Upgrade Kit for TALON robot to provide enhanced depth perception to the operator. This kit previously required the TALON Operator Control Unit to be equipped with the optional touchscreen interface to allow for operator control of the camera convergence angle adjustment. This adjustment allowed for optimal camera convergence independent of the distance from the camera to the object being viewed. Polaris has recently improved the performance of the stereo camera by implementing an Automatic Convergence algorithm in a field programmable gate array in the camera assembly. This algorithm uses scene content to automatically adjust the camera convergence angle, freeing the operator to focus on the task rather than adjustment of the vision system. The autoconvergence capability has been demonstrated on both visible zoom cameras and longwave infrared microbolometer stereo pairs.

Molecular Imaging in the College of Optical Sciences – An Overview of Two Decades of Instrumentation Development

PubMed Central

Furenlid, Lars R.; Barrett, Harrison H.; Barber, H. Bradford; Clarkson, Eric W.; Kupinski, Matthew A.; Liu, Zhonglin; Stevenson, Gail D.; Woolfenden, James M.

2015-01-01

During the past two decades, researchers at the University of Arizona’s Center for Gamma-Ray Imaging (CGRI) have explored a variety of approaches to gamma-ray detection, including scintillation cameras, solid-state detectors, and hybrids such as the intensified Quantum Imaging Device (iQID) configuration where a scintillator is followed by optical gain and a fast CCD or CMOS camera. We have combined these detectors with a variety of collimation schemes, including single and multiple pinholes, parallel-hole collimators, synthetic apertures, and anamorphic crossed slits, to build a large number of preclinical molecular-imaging systems that perform Single-Photon Emission Computed Tomography (SPECT), Positron Emission Tomography (PET), and X-Ray Computed Tomography (CT). In this paper, we discuss the themes and methods we have developed over the years to record and fully use the information content carried by every detected gamma-ray photon. PMID:26236069

Application of gamma imaging techniques for the characterisation of position sensitive gamma detectors

NASA Astrophysics Data System (ADS)

Habermann, T.; Didierjean, F.; Duchêne, G.; Filliger, M.; Gerl, J.; Kojouharov, I.; Li, G.; Pietralla, N.; Schaffner, H.; Sigward, M.-H.

2017-11-01

A device to characterize position-sensitive germanium detectors has been implemented at GSI. The main component of this so called scanning table is a gamma camera that is capable of producing online 2D images of the scanned detector by means of a PET technique. To calibrate the gamma camera Compton imaging is employed. The 2D data can be processed further offline to obtain depth information. Of main interest is the response of the scanned detector in terms of the digitized pulse shapes from the preamplifier. This is an important input for pulse-shape analysis algorithms as they are in use for gamma tracking arrays in gamma spectroscopy. To validate the scanning table, a comparison of its results with a second scanning table implemented at the IPHC Strasbourg is envisaged. For this purpose a pixelated germanium detector has been scanned.

New horizons in cardiac innervation imaging: introduction of novel 18F-labeled PET tracers.

PubMed

Kobayashi, Ryohei; Chen, Xinyu; Werner, Rudolf A; Lapa, Constantin; Javadi, Mehrbod S; Higuchi, Takahiro

2017-12-01

Cardiac sympathetic nervous activity can be uniquely visualized by non-invasive radionuclide imaging techniques due to the fast growing and widespread application of nuclear cardiology in the last few years. The norepinephrine analogue 123 I-meta-iodobenzylguanidine ( 123 I-MIBG) is a single photon emission computed tomography (SPECT) tracer for the clinical implementation of sympathetic nervous imaging for both diagnosis and prognosis of heart failure. Meanwhile, positron emission tomography (PET) imaging has become increasingly attractive because of its higher spatial and temporal resolution compared to SPECT, which allows regional functional and dynamic kinetic analysis. Nevertheless, wider use of cardiac sympathetic nervous PET imaging is still limited mainly due to the demand of costly on-site cyclotrons, which are required for the production of conventional 11 C-labeled (radiological half-life, 20 min) PET tracers. Most recently, more promising 18 F-labeled (half-life, 110 min) PET radiopharmaceuticals targeting sympathetic nervous system have been introduced. These tracers optimize PET imaging and, by using delivery networks, cost less to produce. In this article, the latest advances of sympathetic nervous imaging using 18 F-labeled radiotracers along with their possible applications are reviewed.

Microfluidics: a groundbreaking technology for PET tracer production?

PubMed

Rensch, Christian; Jackson, Alexander; Lindner, Simon; Salvamoser, Ruben; Samper, Victor; Riese, Stefan; Bartenstein, Peter; Wängler, Carmen; Wängler, Björn

2013-07-05

Application of microfluidics to Positron Emission Tomography (PET) tracer synthesis has attracted increasing interest within the last decade. The technical advantages of microfluidics, in particular the high surface to volume ratio and resulting fast thermal heating and cooling rates of reagents can lead to reduced reaction times, increased synthesis yields and reduced by-products. In addition automated reaction optimization, reduced consumption of expensive reagents and a path towards a reduced system footprint have been successfully demonstrated. The processing of radioactivity levels required for routine production, use of microfluidic-produced PET tracer doses in preclinical and clinical imaging as well as feasibility studies on autoradiolytic decomposition have all given promising results. However, the number of microfluidic synthesizers utilized for commercial routine production of PET tracers is very limited. This study reviews the state of the art in microfluidic PET tracer synthesis, highlighting critical design aspects, strengths, weaknesses and presenting several characteristics of the diverse PET market space which are thought to have a significant impact on research, development and engineering of microfluidic devices in this field. Furthermore, the topics of batch- and single-dose production, cyclotron to quality control integration as well as centralized versus de-centralized market distribution models are addressed.

Finite Element Modeling of Reheat Stretch Blow Molding of PET

NASA Astrophysics Data System (ADS)

Krishnan, Dwarak; Dupaix, Rebecca B.

2004-06-01

Poly (ethylene terephthalate) or PET is a polymer used as a packaging material for consumer products such as beverages, food or other liquids, and in other applications including drawn fibers and stretched films. Key features that make it widely used are its transparency, dimensional stability, gas impermeability, impact resistance, and high stiffness and strength in certain preferential directions. These commercially useful properties arise from the fact that PET crystallizes upon deformation above the glass transition temperature. Additionally, this strain-induced crystallization causes the deformation behavior of PET to be highly sensitive to processing conditions. It is thus crucial for engineers to be able to predict its performance at various process temperatures, strain rates and strain states so as to optimize the manufacturing process. In addressing these issues; a finite element analysis of the reheat blow molding process with PET has been carried out using ABAQUS. The simulation employed a constitutive model for PET developed by Dupaix and Boyce et al.. The model includes the combined effects of molecular orientation and strain-induced crystallization on strain hardening when the material is deformed above the glass transition temperature. The simulated bottles were also compared with actual blow molded bottles to evaluate the validity of the simulation.

Hydrogenated amorphous silicon solar cells fabricated at low substrate temperature 110°C on flexible PET substrate

NASA Astrophysics Data System (ADS)

Ramakrishna, M.; Kumari, Juhi; Venkanna, K.; Agarwal, Pratima

2018-05-01

In this paper, we report a-Si:H solar cells fabricated on flexible Polyethylene terephthalate (PET) and corning glass. The a-Si:H thin films were prepared at low substrate temperature (110oC) on corning 1737 glass with different rf powers. The influence of rf power on structural and optoelectronic properties of i-a-Si:H were studied. The films deposited at rf power 50W show less broadening of <ɛ2> peak. This indicates these films are more ordered. With this optimized parameter for i-layer, solar cells fabricated on flexible PET substrate show best efficiency of 3.3% whereas on corning glass 3.82%.

The Impact of Optimal Respiratory Gating and Image Noise on Evaluation of Intratumor Heterogeneity on 18F-FDG PET Imaging of Lung Cancer.

PubMed

Grootjans, Willem; Tixier, Florent; van der Vos, Charlotte S; Vriens, Dennis; Le Rest, Catherine C; Bussink, Johan; Oyen, Wim J G; de Geus-Oei, Lioe-Fee; Visvikis, Dimitris; Visser, Eric P

2016-11-01

Accurate measurement of intratumor heterogeneity using parameters of texture on PET images is essential for precise characterization of cancer lesions. In this study, we investigated the influence of respiratory motion and varying noise levels on quantification of textural parameters in patients with lung cancer. We used an optimal-respiratory-gating algorithm on the list-mode data of 60 lung cancer patients who underwent 18 F-FDG PET. The images were reconstructed using a duty cycle of 35% (percentage of the total acquired PET data). In addition, nongated images of varying statistical quality (using 35% and 100% of the PET data) were reconstructed to investigate the effects of image noise. Several global image-derived indices and textural parameters (entropy, high-intensity emphasis, zone percentage, and dissimilarity) that have been associated with patient outcome were calculated. The clinical impact of optimal respiratory gating and image noise on assessment of intratumor heterogeneity was evaluated using Cox regression models, with overall survival as the outcome measure. The threshold for statistical significance was adjusted for multiple comparisons using Bonferroni correction. In the lower lung lobes, respiratory motion significantly affected quantification of intratumor heterogeneity for all textural parameters (P < 0.007) except entropy (P > 0.007). The mean increase in entropy, dissimilarity, zone percentage, and high-intensity emphasis was 1.3% ± 1.5% (P = 0.02), 11.6% ± 11.8% (P = 0.006), 2.3% ± 2.2% (P = 0.002), and 16.8% ± 17.2% (P = 0.006), respectively. No significant differences were observed for lesions in the upper lung lobes (P > 0.007). Differences in the statistical quality of the PET images affected the textural parameters less than respiratory motion, with no significant difference observed. The median follow-up time was 35 mo (range, 7-39 mo). In multivariate analysis for overall survival, total lesion glycolysis and high-intensity emphasis were the two most relevant image-derived indices and were considered to be independent significant covariates for the model regardless of the image type considered. The tested textural parameters are robust in the presence of respiratory motion artifacts and varying levels of image noise. © 2016 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

Computing camera heading: A study

NASA Astrophysics Data System (ADS)

Zhang, John Jiaxiang

2000-08-01

An accurate estimate of the motion of a camera is a crucial first step for the 3D reconstruction of sites, objects, and buildings from video. Solutions to the camera heading problem can be readily applied to many areas, such as robotic navigation, surgical operation, video special effects, multimedia, and lately even in internet commerce. From image sequences of a real world scene, the problem is to calculate the directions of the camera translations. The presence of rotations makes this problem very hard. This is because rotations and translations can have similar effects on the images, and are thus hard to tell apart. However, the visual angles between the projection rays of point pairs are unaffected by rotations, and their changes over time contain sufficient information to determine the direction of camera translation. We developed a new formulation of the visual angle disparity approach, first introduced by Tomasi, to the camera heading problem. Our new derivation makes theoretical analysis possible. Most notably, a theorem is obtained that locates all possible singularities of the residual function for the underlying optimization problem. This allows identifying all computation trouble spots beforehand, and to design reliable and accurate computational optimization methods. A bootstrap-jackknife resampling method simultaneously reduces complexity and tolerates outliers well. Experiments with image sequences show accurate results when compared with the true camera motion as measured with mechanical devices.

Pharmaceutical development of a parenteral formulation of the novel anti-tumor agent carzelesin (U-80,244).

PubMed

Jonkman-de Vries, J D; de Graaff-Teulen, M J; Henrar, R E; Kettenes-van den Bosch, J J; Bult, A; Beijnen, J H

1994-01-01

The aim of this study was to design a parenteral dosage form for the investigational cytotoxic drug carzelesin. A stable formulation in PET (Polyethylene glycol 400/absolute ethanol/Tween 80, 6:3:1, v/v/v) was developed. The prototype, containing 0.50 mg carzelesin in 2.0 ml PET formulation, was found to be the optimal formulation in terms of solubility, stability and dosage requirements in phase I clinical trials. Quality control of the formulation showed that the pharmaceutical preparation of carzelesin in PET is not negatively influenced by the manufacturing process. Shelf life studies demonstrated that the formulation is stable for at least 1 year, when stored at -30 degrees C in the dark. In addition, the stability of carzelesin in the PET formulation is discussed as a function of temperature, additives and after dilution in infusion fluids.

Red ball ranging optimization based on dual camera ranging method

NASA Astrophysics Data System (ADS)

Kuang, Lei; Sun, Weijia; Liu, Jiaming; Tang, Matthew Wai-Chung

2018-05-01

In this paper, the process of positioning and moving to target red ball by NAO robot through its camera system is analyzed and improved using the dual camera ranging method. The single camera ranging method, which is adapted by NAO robot, was first studied and experimented. Since the existing error of current NAO Robot is not a single variable, the experiments were divided into two parts to obtain more accurate single camera ranging experiment data: forward ranging and backward ranging. Moreover, two USB cameras were used in our experiments that adapted Hough's circular method to identify a ball, while the HSV color space model was used to identify red color. Our results showed that the dual camera ranging method reduced the variance of error in ball tracking from 0.68 to 0.20.

Thermal regulation for APDs in a 1 mm(3) resolution clinical PET camera: design, simulation and experimental verification.

PubMed

Zhai, Jinjian; Vandenbroucke, Arne; Levin, Craig S

2014-07-21

We are developing a 1 mm(3) resolution positron emission tomography camera dedicated to breast imaging. The camera collects high energy photons emitted from radioactively labeled agents introduced in the patients in order to detect molecular signatures of breast cancer. The camera comprises many layers of lutetium yttrium oxyorthosilicate (LYSO) scintillation crystals coupled to position sensitive avalanche photodiodes (PSAPDs). The main objectives of the studies presented in this paper are to investigate the temperature profile of the layers of LYSO-PSAPD detectors (a.k.a. 'fins') residing in the camera and to use these results to present the design of the thermal regulation system for the front end of the camera. The study was performed using both experimental methods and simulation. We investigated a design with a heat-dissipating fin. Three fin configurations are tested: fin with Al windows (FwW), fin without Al windows (FwoW) and fin with alumina windows (FwAW). A Fluent® simulation was conducted to study the experimentally inaccessible temperature of the PSAPDs. For the best configuration (FwW), the temperature difference from the center to a point near the edge is 1.0 K when 1.5 A current was applied to the Peltier elements. Those of FwoW and FwAW are 2.6 K and 1.7 K, respectively. We conclude that the design of a heat-dissipating fin configuration with 'aluminum windows' (FwW) that borders the scintillation crystal arrays of 16 adjacent detector modules has better heat dissipation capabilities than the design without 'aluminum windows' (FwoW) and the design with 'alumina windows' (FwAW), respectively.

Automated tumour boundary delineation on 18F-FDG PET images using active contour coupled with shifted-optimal thresholding method

NASA Astrophysics Data System (ADS)

Khamwan, Kitiwat; Krisanachinda, Anchali; Pluempitiwiriyawej, Charnchai

2012-10-01

This study presents an automatic method to trace the boundary of the tumour in positron emission tomography (PET) images. It has been discovered that Otsu's threshold value is biased when the within-class variances between the object and the background are significantly different. To solve the problem, a double-stage threshold search that minimizes the energy between the first Otsu's threshold and the maximum intensity value is introduced. Such shifted-optimal thresholding is embedded into a region-based active contour so that both algorithms are performed consecutively. The efficiency of the method is validated using six sphere inserts (0.52-26.53 cc volume) of the IEC/2001 torso phantom. Both spheres and phantom were filled with 18F solution with four source-to-background ratio (SBR) measurements of PET images. The results illustrate that the tumour volumes segmented by combined algorithm are of higher accuracy than the traditional active contour. The method had been clinically implemented in ten oesophageal cancer patients. The results are evaluated and compared with the manual tracing by an experienced radiation oncologist. The advantage of the algorithm is the reduced erroneous delineation that improves the precision and accuracy of PET tumour contouring. Moreover, the combined method is robust, independent of the SBR threshold-volume curves, and it does not require prior lesion size measurement.

The effect of microchannel plate gain depression on PAPA photon counting cameras

NASA Astrophysics Data System (ADS)

Sams, Bruce J., III

1991-03-01

PAPA (precision analog photon address) cameras are photon counting imagers which employ microchannel plates (MCPs) for image intensification. They have been used extensively in astronomical speckle imaging. The PAPA camera can produce artifacts when light incident on its MCP is highly concentrated. The effect is exacerbated by adjusting the strobe detection level too low, so that the camera accepts very small MCP pulses. The artifacts can occur even at low total count rates if the image has highly a concentrated bright spot. This paper describes how to optimize PAPA camera electronics, and describes six techniques which can avoid or minimize addressing errors.

LSST Camera Optics Design

DOE Office of Scientific and Technical Information (OSTI.GOV)

Riot, V J; Olivier, S; Bauman, B

2012-05-24

The Large Synoptic Survey Telescope (LSST) uses a novel, three-mirror, telescope design feeding a camera system that includes a set of broad-band filters and three refractive corrector lenses to produce a flat field at the focal plane with a wide field of view. Optical design of the camera lenses and filters is integrated in with the optical design of telescope mirrors to optimize performance. We discuss the rationale for the LSST camera optics design, describe the methodology for fabricating, coating, mounting and testing the lenses and filters, and present the results of detailed analyses demonstrating that the camera optics willmore » meet their performance goals.« less

Refining the Workflow of UV Camera Measurements: Data Collection from Low Emission Rate Volcanoes under Variable Conditions

NASA Astrophysics Data System (ADS)

Brewer, I. D.; Werner, C. A.; Nadeau, P. A.

2010-12-01

UV camera systems are gaining popularity worldwide for quantifying SO2 column abundances and emission rates from volcanoes, which serve as primary measures of volcanic hazard and aid in eruption forecasting. To date many of the investigations have focused on fairly active and routinely monitored volcanoes under optimal conditions. Some recent studies have begun to recommend protocols and procedures for data collection, but additional questions still need to be addressed. In this study we attempt to answer these questions, and also present results from volcanoes that are rarely monitored. Conditions at these volcanoes are typically sub-optimal for UV camera measurements. Discussion of such data is essential in the assessment of the wider applicability of UV camera measurements for SO2 monitoring purposes. Data discussed herein consists of plume images from volcanoes with relatively low emission rates, with varying weather conditions and from various distances (2-12 km). These include Karangatang Volcano (Indonesia), Mount St. Helens (Washington, USA), and Augustine and Redoubt Volcanoes (Alaska, USA). High emission rate data were also collected at Kilauea Volcano (Hawaii, USA), and blue sky test images with no plume were collected at Mammoth Mountain (California, USA). All data were collected between 2008 and 2010 using both single-filter (307 nm) and dual-filter (307 nm/326 nm) systems and were accompanied by FLYSPEC measurements. With the dual-filter systems, both a filter wheel setup and a synchronous-imaging dual-camera setup were employed. Data collection and processing questions included (1) what is the detection limit of the camera, (2) how large is the variability in raw camera output, (3) how do camera optics affect the measurements and how can this be corrected, (4) how much variability is observed in calibration under various conditions, (5) what is the optimal workflow for image collection and processing, and (6) what is the range of camera operating conditions? Besides emission rates from these infrequently monitored volcanoes, the results of this study include a recommended workflow and procedure for image collection and calibration, and a MATLAB-based algorithm for batch processing, thereby enabling accurate emission rates at 1 Hz when a synchronous-imaging dual-camera setup is used.

Respiratory motion correction in 4D-PET by simultaneous motion estimation and image reconstruction (SMEIR)

PubMed Central

Kalantari, Faraz; Li, Tianfang; Jin, Mingwu; Wang, Jing

2016-01-01

In conventional 4D positron emission tomography (4D-PET), images from different frames are reconstructed individually and aligned by registration methods. Two issues that arise with this approach are as follows: 1) the reconstruction algorithms do not make full use of projection statistics; and 2) the registration between noisy images can result in poor alignment. In this study, we investigated the use of simultaneous motion estimation and image reconstruction (SMEIR) methods for motion estimation/correction in 4D-PET. A modified ordered-subset expectation maximization algorithm coupled with total variation minimization (OSEM-TV) was used to obtain a primary motion-compensated PET (pmc-PET) from all projection data, using Demons derived deformation vector fields (DVFs) as initial motion vectors. A motion model update was performed to obtain an optimal set of DVFs in the pmc-PET and other phases, by matching the forward projection of the deformed pmc-PET with measured projections from other phases. The OSEM-TV image reconstruction was repeated using updated DVFs, and new DVFs were estimated based on updated images. A 4D-XCAT phantom with typical FDG biodistribution was generated to evaluate the performance of the SMEIR algorithm in lung and liver tumors with different contrasts and different diameters (10 to 40 mm). The image quality of the 4D-PET was greatly improved by the SMEIR algorithm. When all projections were used to reconstruct 3D-PET without motion compensation, motion blurring artifacts were present, leading up to 150% tumor size overestimation and significant quantitative errors, including 50% underestimation of tumor contrast and 59% underestimation of tumor uptake. Errors were reduced to less than 10% in most images by using the SMEIR algorithm, showing its potential in motion estimation/correction in 4D-PET. PMID:27385378

Characterization and engineering of a plastic-degrading aromatic polyesterase.

PubMed

Austin, Harry P; Allen, Mark D; Donohoe, Bryon S; Rorrer, Nicholas A; Kearns, Fiona L; Silveira, Rodrigo L; Pollard, Benjamin C; Dominick, Graham; Duman, Ramona; El Omari, Kamel; Mykhaylyk, Vitaliy; Wagner, Armin; Michener, William E; Amore, Antonella; Skaf, Munir S; Crowley, Michael F; Thorne, Alan W; Johnson, Christopher W; Woodcock, H Lee; McGeehan, John E; Beckham, Gregg T

2018-05-08

Poly(ethylene terephthalate) (PET) is one of the most abundantly produced synthetic polymers and is accumulating in the environment at a staggering rate as discarded packaging and textiles. The properties that make PET so useful also endow it with an alarming resistance to biodegradation, likely lasting centuries in the environment. Our collective reliance on PET and other plastics means that this buildup will continue unless solutions are found. Recently, a newly discovered bacterium, Ideonella sakaiensis 201-F6, was shown to exhibit the rare ability to grow on PET as a major carbon and energy source. Central to its PET biodegradation capability is a secreted PETase (PET-digesting enzyme). Here, we present a 0.92 Å resolution X-ray crystal structure of PETase, which reveals features common to both cutinases and lipases. PETase retains the ancestral α/β-hydrolase fold but exhibits a more open active-site cleft than homologous cutinases. By narrowing the binding cleft via mutation of two active-site residues to conserved amino acids in cutinases, we surprisingly observe improved PET degradation, suggesting that PETase is not fully optimized for crystalline PET degradation, despite presumably evolving in a PET-rich environment. Additionally, we show that PETase degrades another semiaromatic polyester, polyethylene-2,5-furandicarboxylate (PEF), which is an emerging, bioderived PET replacement with improved barrier properties. In contrast, PETase does not degrade aliphatic polyesters, suggesting that it is generally an aromatic polyesterase. These findings suggest that additional protein engineering to increase PETase performance is realistic and highlight the need for further developments of structure/activity relationships for biodegradation of synthetic polyesters. Copyright © 2018 the Author(s). Published by PNAS.

Respiratory motion correction in 4D-PET by simultaneous motion estimation and image reconstruction (SMEIR)

NASA Astrophysics Data System (ADS)

Kalantari, Faraz; Li, Tianfang; Jin, Mingwu; Wang, Jing

2016-08-01

In conventional 4D positron emission tomography (4D-PET), images from different frames are reconstructed individually and aligned by registration methods. Two issues that arise with this approach are as follows: (1) the reconstruction algorithms do not make full use of projection statistics; and (2) the registration between noisy images can result in poor alignment. In this study, we investigated the use of simultaneous motion estimation and image reconstruction (SMEIR) methods for motion estimation/correction in 4D-PET. A modified ordered-subset expectation maximization algorithm coupled with total variation minimization (OSEM-TV) was used to obtain a primary motion-compensated PET (pmc-PET) from all projection data, using Demons derived deformation vector fields (DVFs) as initial motion vectors. A motion model update was performed to obtain an optimal set of DVFs in the pmc-PET and other phases, by matching the forward projection of the deformed pmc-PET with measured projections from other phases. The OSEM-TV image reconstruction was repeated using updated DVFs, and new DVFs were estimated based on updated images. A 4D-XCAT phantom with typical FDG biodistribution was generated to evaluate the performance of the SMEIR algorithm in lung and liver tumors with different contrasts and different diameters (10-40 mm). The image quality of the 4D-PET was greatly improved by the SMEIR algorithm. When all projections were used to reconstruct 3D-PET without motion compensation, motion blurring artifacts were present, leading up to 150% tumor size overestimation and significant quantitative errors, including 50% underestimation of tumor contrast and 59% underestimation of tumor uptake. Errors were reduced to less than 10% in most images by using the SMEIR algorithm, showing its potential in motion estimation/correction in 4D-PET.

Respiratory Motion Management in PET/CT: Applications and Clinical Usefulness.

PubMed

Guerra, Luca; Ponti, Elena De; Morzenti, Sabrina; Spadavecchia, Chiara; Crivellaro, Cinzia

2017-01-01

Breathing movement can introduce heavy bias in both image quality and quantitation in PET/CT. The aim of this paper is a review of the literature to evaluate the benefit of respiratory gating in terms of image quality, quantification and lesion detectability. A review of the literature published in the last 10 years and dealing with gated PET/CT technique has been performed, focusing on improvement in quantification, lesion detectability and diagnostic accuracy in neoplastic lesion. In addition, the improvement in the definition of radiotherapy planning has been evaluated. There is a consistent increase of the Standardized Uptake Value (SUV) in gated PET images when compared to ungated ones, particularly for lesions located in liver and in lung. Respiratory gating can also increase sensitivity, specificity and accuracy of PET/CT. Gated PET/CT can be used for radiation therapy planning, reducing the uncertainty in target definition, optimizing the volume to be treated and reducing the possibility of "missing" during the dose delivery. Moreover, new technologies, able to define the movement of lesions and organs directly from the PET sinogram, can solve some problems that currently are limiting the clinical use of gated PET/CT (i.e.: extended acquisition time, radiation exposure). The published literature demonstrated that respiratory gating PET/CT is a valid technique to improve quantification, lesion detectability of lung and liver tumors and can better define the radiotherapy planning of moving lesions and organs. If new technical improvements for motion compensation will be clinically validated, gated technique could be applied routinely in any PET/CT scan. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Fluorodeoxyglucose positron emission tomography for detection of tumor recurrence following radiofrequency ablation in retrospective cohort of stage I lung cancer.

PubMed

Wang, Yingbing; Lanuti, Michael; Bernheim, Adam; Shepard, Jo-Anne O; Sharma, Amita

2018-05-03

The goal of this study was to define patterns for tumor recurrence on PET following RFA, compare time to imaging recurrence by PET versus CT, evaluate whether pre-treatment tumor uptake predicts recurrence and propose an optimal post-RFA surveillance strategy. A retrospective cohort study was performed of biopsy confirmed primary stage I lung cancers treated with RFA. FDG PET and near contemporaneous diagnostic CT imaging pre-ablation, within 30 days post-ablation, and beyond 6 months were independently and retrospectively evaluated for features supportive of recurrence. Time to imaging recurrence by PET (TTR_PET) and by CT (TTR_CT) were determined and compared. FDG avidity of untreated tumors was compared between recurrent and non-recurrent groups. Thirteen recurrences after 72 RFA treatments were confirmed by diagnostic CT. All recurrences were associated with focally intense and increasing FDG uptake beyond 6 months (sensitivity 100%; specificity 98.5%). Mean TTR_PET was 14 months compared to mean TTR_CT of 17 months (not statistically significant). Normalized SUVmax and total lesions glycolysis of lung cancers that recurred after RFA was 4.0 and 6.0, respectively compared to 2.8 and 5.0, respectively for cancers that did not recur (p = .068). A pattern of focally intense and increasing FDG PET uptake has high sensitivity and specificity for detecting recurrent lung cancer following RFA. Surveillance after RFA should include a contrast enhanced diagnostic CT at 1 month to diagnose procedural complications, PET at 6 months as a post-treatment metabolic baseline (with diagnostic CT if PET is abnormal) and alternating diagnostic CTs or PET every 6 months for 2 years.

Evaluation of PeneloPET Simulations of Biograph PET/CT Scanners

NASA Astrophysics Data System (ADS)

Abushab, K. M.; Herraiz, J. L.; Vicente, E.; Cal-González, J.; España, S.; Vaquero, J. J.; Jakoby, B. W.; Udías, J. M.

2016-06-01

Monte Carlo (MC) simulations are widely used in positron emission tomography (PET) for optimizing detector design, acquisition protocols, and evaluating corrections and reconstruction methods. PeneloPET is a MC code based on PENELOPE, for PET simulations which considers detector geometry, acquisition electronics and materials, and source definitions. While PeneloPET has been successfully employed and validated with small animal PET scanners, it required a proper validation with clinical PET scanners including time-of-flight (TOF) information. For this purpose, we chose the family of Biograph PET/CT scanners: the Biograph True-Point (B-TP), Biograph True-Point with TrueV (B-TPTV) and the Biograph mCT. They have similar block detectors and electronics, but a different number of rings and configuration. Some effective parameters of the simulations, such as the dead-time and the size of the reflectors in the detectors, were adjusted to reproduce the sensitivity and noise equivalent count (NEC) rate of the B-TPTV scanner. These parameters were then used to make predictions of experimental results such as sensitivity, NEC rate, spatial resolution, and scatter fraction (SF), from all the Biograph scanners and some variations of them (energy windows and additional rings of detectors). Predictions agree with the measured values for the three scanners, within 7% (sensitivity and NEC rate) and 5% (SF). The resolution obtained for the B-TPTV is slightly better (10%) than the experimental values. In conclusion, we have shown that PeneloPET is suitable for simulating and investigating clinical systems with good accuracy and short computational time, though some effort tuning of a few parameters of the scanners modeled may be needed in case that the full details of the scanners studied are not available.

Anatomical patterns of colonization of pets with staphylococcal species in homes of people with methicillin-resistant Staphylococcus aureus (MRSA) skin or soft tissue infection (SSTI).

PubMed

Iverson, S A; Brazil, A M; Ferguson, J M; Nelson, K; Lautenbach, E; Rankin, S C; Morris, D O; Davis, M F

2015-03-23

Methicillin-resistant strains of Staphylococcus aureus (MRSA), Staphylococcus pseudintermedius (MRSP), and other pathogenic staphylococci can cause infections in companion animals and humans. Identification of colonized animals is fundamental to research and practice needs, but harmonized methods have not yet been established. To establish the optimal anatomic site for the recovery of methicillin-resistant coagulase positive staphylococci (CPS), survey data and swabs were collected from 196 pets (dogs, cats, reptiles, birds, fish and pocket pets) that lived in households with an MRSA-infected person. Using broth-enrichment culture and PCR for speciation, S. aureus was identified in 27 of 179 (15%) pets sampled at baseline and 19 of 125 (15%) pets sampled at a three-month follow-up home visit. S. pseudintermedius was isolated from 33 of 179 (18%) pets sampled at baseline and 21 of 125 (17%) of pets sampled at follow-up. The baseline MRSA and MRSP prevalence was 8% and 1% respectively from 145 mammalian pets. The follow-up MRSA and MRSP prevalence was 7% and <1% respectively from 95 mammalian pets. The mouth was the most sensitive single site sampled for isolation of S. aureus and S. pseudintermedius in mammals. In a subset of pets, from which all available isolates were identified, dual carriage of S. aureus and S. pseudintermedius was 22% at baseline and 11% at follow-up. These results identify the mouth as the most sensitive site to screen for pathogenic staphylococci and suggest that it should be included in sampling protocols. Copyright © 2015 Elsevier B.V. All rights reserved.

FDG-PET/CT(A) imaging in large vessel vasculitis and polymyalgia rheumatica: joint procedural recommendation of the EANM, SNMMI, and the PET Interest Group (PIG), and endorsed by the ASNC.

PubMed

Slart, Riemer H J A

2018-07-01

Large vessel vasculitis (LVV) is defined as a disease mainly affecting the large arteries, with two major variants, Takayasu arteritis (TA) and giant cell arteritis (GCA). GCA often coexists with polymyalgia rheumatica (PMR) in the same patient, since both belong to the same disease spectrum. FDG-PET/CT is a functional imaging technique which is an established tool in oncology, and has also demonstrated a role in the field of inflammatory diseases. Functional FDG-PET combined with anatomical CT angiography, FDG-PET/CT(A), may be of synergistic value for optimal diagnosis, monitoring of disease activity, and evaluating damage progression in LVV. There are currently no guidelines regarding PET imaging acquisition for LVV and PMR, even though standardization is of the utmost importance in order to facilitate clinical studies and for daily clinical practice. This work constitutes a joint procedural recommendation on FDG-PET/CT(A) imaging in large vessel vasculitis (LVV) and PMR from the Cardiovascular and Inflammation & Infection Committees of the European Association of Nuclear Medicine (EANM), the Cardiovascular Council of the Society of Nuclear Medicine and Molecular Imaging (SNMMI), and the PET Interest Group (PIG), and endorsed by the American Society of Nuclear Cardiology (ASNC). The aim of this joint paper is to provide recommendations and statements, based on the available evidence in the literature and consensus of experts in the field, for patient preparation, and FDG-PET/CT(A) acquisition and interpretation for the diagnosis and follow-up of patients with suspected or diagnosed LVV and/or PMR. This position paper aims to set an internationally accepted standard for FDG-PET/CT(A) imaging and reporting of LVV and PMR.

ATLAAS: an automatic decision tree-based learning algorithm for advanced image segmentation in positron emission tomography.

PubMed

Berthon, Beatrice; Marshall, Christopher; Evans, Mererid; Spezi, Emiliano

2016-07-07

Accurate and reliable tumour delineation on positron emission tomography (PET) is crucial for radiotherapy treatment planning. PET automatic segmentation (PET-AS) eliminates intra- and interobserver variability, but there is currently no consensus on the optimal method to use, as different algorithms appear to perform better for different types of tumours. This work aimed to develop a predictive segmentation model, trained to automatically select and apply the best PET-AS method, according to the tumour characteristics. ATLAAS, the automatic decision tree-based learning algorithm for advanced segmentation is based on supervised machine learning using decision trees. The model includes nine PET-AS methods and was trained on a 100 PET scans with known true contour. A decision tree was built for each PET-AS algorithm to predict its accuracy, quantified using the Dice similarity coefficient (DSC), according to the tumour volume, tumour peak to background SUV ratio and a regional texture metric. The performance of ATLAAS was evaluated for 85 PET scans obtained from fillable and printed subresolution sandwich phantoms. ATLAAS showed excellent accuracy across a wide range of phantom data and predicted the best or near-best segmentation algorithm in 93% of cases. ATLAAS outperformed all single PET-AS methods on fillable phantom data with a DSC of 0.881, while the DSC for H&N phantom data was 0.819. DSCs higher than 0.650 were achieved in all cases. ATLAAS is an advanced automatic image segmentation algorithm based on decision tree predictive modelling, which can be trained on images with known true contour, to predict the best PET-AS method when the true contour is unknown. ATLAAS provides robust and accurate image segmentation with potential applications to radiation oncology.

ATLAAS: an automatic decision tree-based learning algorithm for advanced image segmentation in positron emission tomography

NASA Astrophysics Data System (ADS)

Berthon, Beatrice; Marshall, Christopher; Evans, Mererid; Spezi, Emiliano

2016-07-01

Accurate and reliable tumour delineation on positron emission tomography (PET) is crucial for radiotherapy treatment planning. PET automatic segmentation (PET-AS) eliminates intra- and interobserver variability, but there is currently no consensus on the optimal method to use, as different algorithms appear to perform better for different types of tumours. This work aimed to develop a predictive segmentation model, trained to automatically select and apply the best PET-AS method, according to the tumour characteristics. ATLAAS, the automatic decision tree-based learning algorithm for advanced segmentation is based on supervised machine learning using decision trees. The model includes nine PET-AS methods and was trained on a 100 PET scans with known true contour. A decision tree was built for each PET-AS algorithm to predict its accuracy, quantified using the Dice similarity coefficient (DSC), according to the tumour volume, tumour peak to background SUV ratio and a regional texture metric. The performance of ATLAAS was evaluated for 85 PET scans obtained from fillable and printed subresolution sandwich phantoms. ATLAAS showed excellent accuracy across a wide range of phantom data and predicted the best or near-best segmentation algorithm in 93% of cases. ATLAAS outperformed all single PET-AS methods on fillable phantom data with a DSC of 0.881, while the DSC for H&N phantom data was 0.819. DSCs higher than 0.650 were achieved in all cases. ATLAAS is an advanced automatic image segmentation algorithm based on decision tree predictive modelling, which can be trained on images with known true contour, to predict the best PET-AS method when the true contour is unknown. ATLAAS provides robust and accurate image segmentation with potential applications to radiation oncology.

18F-FDG PET-CT after Neoadjuvant Chemoradiotherapy in Esophageal Cancer Patients to Optimize Surgical Decision Making

PubMed Central

Anderegg, Maarten C. J.; de Groof, Elisabeth J.; Gisbertz, Suzanne S.; Bennink, Roel J.; Lagarde, Sjoerd M.; Klinkenbijl, Jean H. G.; Dijkgraaf, Marcel G. W.; Bergman, Jacques J. G. H. M.; Hulshof, Maarten C. C. M.; van Laarhoven, Hanneke W. M.; van Berge Henegouwen, Mark I.

2015-01-01

Background Prognosis of esophageal cancer patients can be significantly improved by neoadjuvant chemoradiotherapy (nCRT). Given the aggressive nature of esophageal tumors, it is conceivable that in a significant portion of patients treated with nCRT, dissemination already becomes manifest during the period of nCRT. The aim of this retrospective study was to determine the value and diagnostic accuracy of PET-CT after neoadjuvant chemoradiotherapy to identify patients with metastases preoperatively in order to prevent non-curative surgery. Methods From January 2011 until February 2013 esophageal cancer patients deemed eligible for a curative approach with nCRT and surgical resection underwent a PET-CT after completion of nCRT. If abnormalities on PET-CT were suspected metastases, histological proof was acquired. A clinical decision model was designed to assess the cost-effectiveness of this diagnostic strategy. Results 156 patients underwent a PET-CT after nCRT. In 31 patients (19.9%) PET-CT showed abnormalities suspicious for dissemination, resulting in 17 cases of proven metastases (10.9%). Of the patients without proven metastases 133 patients were operated. In 6 of these 133 cases distant metastases were detected intraoperatively, corresponding to 4.5% false-negative results. The standard introduction of a post-neoadjuvant therapy PET-CT led to a reduction of overall health care costs per patient compared to a scenario without restaging with PET-CT ($34,088 vs. $36,490). Conclusion In 10.9% of esophageal cancer patients distant metastases were detected by standard PET-CT after neoadjuvant chemoradiotherapy. To avoid non-curative resections we advocate post-neoadjuvant therapy PET-CT as a cost-effective step in the standard work-up of candidates for surgery. PMID:26529313

Ringfield lithographic camera

DOEpatents

Sweatt, W.C.

1998-09-08

A projection lithography camera is presented with a wide ringfield optimized so as to make efficient use of extreme ultraviolet radiation from a large area radiation source (e.g., D{sub source} {approx_equal} 0.5 mm). The camera comprises four aspheric mirrors optically arranged on a common axis of symmetry. The camera includes an aperture stop that is accessible through a plurality of partial aperture stops to synthesize the theoretical aperture stop. Radiation from a mask is focused to form a reduced image on a wafer, relative to the mask, by reflection from the four aspheric mirrors. 11 figs.

Applications of a shadow camera system for energy meteorology

NASA Astrophysics Data System (ADS)

Kuhn, Pascal; Wilbert, Stefan; Prahl, Christoph; Garsche, Dominik; Schüler, David; Haase, Thomas; Ramirez, Lourdes; Zarzalejo, Luis; Meyer, Angela; Blanc, Philippe; Pitz-Paal, Robert

2018-02-01

Downward-facing shadow cameras might play a major role in future energy meteorology. Shadow cameras directly image shadows on the ground from an elevated position. They are used to validate other systems (e.g. all-sky imager based nowcasting systems, cloud speed sensors or satellite forecasts) and can potentially provide short term forecasts for solar power plants. Such forecasts are needed for electricity grids with high penetrations of renewable energy and can help to optimize plant operations. In this publication, two key applications of shadow cameras are briefly presented.

Specification and estimation of sources of bias affecting neurological studies in PET/MR with an anatomical brain phantom

NASA Astrophysics Data System (ADS)

Teuho, J.; Johansson, J.; Linden, J.; Saunavaara, V.; Tolvanen, T.; Teräs, M.

2014-01-01

Selection of reconstruction parameters has an effect on the image quantification in PET, with an additional contribution from a scanner-specific attenuation correction method. For achieving comparable results in inter- and intra-center comparisons, any existing quantitative differences should be identified and compensated for. In this study, a comparison between PET, PET/CT and PET/MR is performed by using an anatomical brain phantom, to identify and measure the amount of bias caused due to differences in reconstruction and attenuation correction methods especially in PET/MR. Differences were estimated by using visual, qualitative and quantitative analysis. The qualitative analysis consisted of a line profile analysis for measuring the reproduction of anatomical structures and the contribution of the amount of iterations to image contrast. The quantitative analysis consisted of measurement and comparison of 10 anatomical VOIs, where the HRRT was considered as the reference. All scanners reproduced the main anatomical structures of the phantom adequately, although the image contrast on the PET/MR was inferior when using a default clinical brain protocol. Image contrast was improved by increasing the amount of iterations from 2 to 5 while using 33 subsets. Furthermore, a PET/MR-specific bias was detected, which resulted in underestimation of the activity values in anatomical structures closest to the skull, due to the MR-derived attenuation map that ignores the bone. Thus, further improvements for the PET/MR reconstruction and attenuation correction could be achieved by optimization of RAMLA-specific reconstruction parameters and implementation of bone to the attenuation template.

Optimal reproducibility of gated sestamibi and thallium myocardial perfusion study left ventricular ejection fractions obtained on a solid-state CZT cardiac camera requires operator input.

PubMed

Cherk, Martin H; Ky, Jason; Yap, Kenneth S K; Campbell, Patrina; McGrath, Catherine; Bailey, Michael; Kalff, Victor

2012-08-01

To evaluate the reproducibility of serial re-acquisitions of gated Tl-201 and Tc-99m sestamibi left ventricular ejection fraction (LVEF) measurements obtained on a new generation solid-state cardiac camera system during myocardial perfusion imaging and the importance of manual operator optimization of left ventricular wall tracking. Resting blinded automated (auto) and manual operator optimized (opt) LVEF measurements were measured using ECT toolbox (ECT) and Cedars-Sinai QGS software in two separate cohorts of 55 Tc-99m sestamibi (MIBI) and 50 thallium (Tl-201) myocardial perfusion studies (MPS) acquired in both supine and prone positions on a cadmium zinc telluride (CZT) solid-state camera system. Resting supine and prone automated LVEF measurements were similarly obtained in a further separate cohort of 52 gated cardiac blood pool scans (GCBPS) for validation of methodology and comparison. Appropriate use of Bland-Altman, chi-squared and Levene's equality of variance tests was used to analyse the resultant data comparisons. For all radiotracer and software combinations, manual checking and optimization of valve planes (+/- centre radius with ECT software) resulted in significant improvement in MPS LVEF reproducibility that approached that of planar GCBPS. No difference was demonstrated between optimized MIBI/Tl-201 QGS and planar GCBPS LVEF reproducibility (P = .17 and P = .48, respectively). ECT required significantly more manual optimization compared to QGS software in both supine and prone positions independent of radiotracer used (P < .02). Reproducibility of gated sestamibi and Tl-201 LVEF measurements obtained during myocardial perfusion imaging with ECT toolbox or QGS software packages using a new generation solid-state cardiac camera with improved image quality approaches that of planar GCBPS however requires visual quality control and operator optimization of left ventricular wall tracking for best results. Using this superior cardiac technology, Tl-201 reproducibility also appears at least equivalent to sestamibi for measuring LVEF.

A novel dual-camera calibration method for 3D optical measurement

NASA Astrophysics Data System (ADS)

Gai, Shaoyan; Da, Feipeng; Dai, Xianqiang

2018-05-01

A novel dual-camera calibration method is presented. In the classic methods, the camera parameters are usually calculated and optimized by the reprojection error. However, for a system designed for 3D optical measurement, this error does not denote the result of 3D reconstruction. In the presented method, a planar calibration plate is used. In the beginning, images of calibration plate are snapped from several orientations in the measurement range. The initial parameters of the two cameras are obtained by the images. Then, the rotation and translation matrix that link the frames of two cameras are calculated by using method of Centroid Distance Increment Matrix. The degree of coupling between the parameters is reduced. Then, 3D coordinates of the calibration points are reconstructed by space intersection method. At last, the reconstruction error is calculated. It is minimized to optimize the calibration parameters. This error directly indicates the efficiency of 3D reconstruction, thus it is more suitable for assessing the quality of dual-camera calibration. In the experiments, it can be seen that the proposed method is convenient and accurate. There is no strict requirement on the calibration plate position in the calibration process. The accuracy is improved significantly by the proposed method.

WE-AB-204-10: Evaluation of a Novel Dedicated Breast PET System (Mammi-PET)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Long, Z; Swanson, T; O’Connor, M

2015-06-15

Purpose: To evaluate the performance characteristics of a novel dedicated breast PET system (Mammi-PET, Oncovision). The system has 2 detector rings giving axial/transaxial field of view of 8/17 cm. Each ring consists of 12 monolithic LYSO modules coupled to PSPMTs. Methods: Uniformity, sensitivity, energy and spatial resolution were measured according to NEMA standards. Count rate performance was investigated using a source of F-18 (1384uCi) decayed over 5 half-lives. A prototype PET phantom was imaged for 20 min to evaluate image quality, recovery coefficients and partial volume effects. Under an IRB-approved protocol, 11 patients who just underwent whole body PET/CT examsmore » were imaged prone with the breast pendulant at 5–10 minutes/breast. Image quality was assessed with and without scatter/attenuation correction and using different reconstruction algorithms. Results: Integral/differential uniformity were 9.8%/6.0% respectively. System sensitivity was 2.3% on axis, 2.2% and 2.8% at 3.8 cm and 7.8 cm off-axis. Mean energy resolution of all modules was 23.3%. Spatial resolution (FWHM) was 1.82 mm and 2.90 mm on axis and 5.8 cm off axis. Three cylinders (14 mm diameter) in the PET phantom were filled with activity concentration ratios of 4:1, 3:1, and 2:1 relative to the background. Measured cylinder to background ratios were 2.6, 1.8 and 1.5 (without corrections) and 3.6, 2.3 and 1.5 (with attenuation/scatter correction). Five cylinders (14, 10, 6, 4 and 2 mm diameter) each with an activity ratio of 4:1 were measured and showed recovery coefficients of 1, 0.66, 0.45, 0.18 and 0.18 (without corrections), and 1, 0.53, 0.30, 0.13 and 0 (with attenuation/scatter correction). Optimal phantom image quality was obtained with 3D MLEM algorithm, >20 iterations and without attenuation/scatter correction. Conclusion: The MAMMI system demonstrated good performance characteristics. Further work is needed to determine the optimal reconstruction parameters for qualitative and quantitative applications.« less

Generalized PSF modeling for optimized quantitation in PET imaging.

PubMed

Ashrafinia, Saeed; Mohy-Ud-Din, Hassan; Karakatsanis, Nicolas A; Jha, Abhinav K; Casey, Michael E; Kadrmas, Dan J; Rahmim, Arman

2017-06-21

Point-spread function (PSF) modeling offers the ability to account for resolution degrading phenomena within the PET image generation framework. PSF modeling improves resolution and enhances contrast, but at the same time significantly alters image noise properties and induces edge overshoot effect. Thus, studying the effect of PSF modeling on quantitation task performance can be very important. Frameworks explored in the past involved a dichotomy of PSF versus no-PSF modeling. By contrast, the present work focuses on quantitative performance evaluation of standard uptake value (SUV) PET images, while incorporating a wide spectrum of PSF models, including those that under- and over-estimate the true PSF, for the potential of enhanced quantitation of SUVs. The developed framework first analytically models the true PSF, considering a range of resolution degradation phenomena (including photon non-collinearity, inter-crystal penetration and scattering) as present in data acquisitions with modern commercial PET systems. In the context of oncologic liver FDG PET imaging, we generated 200 noisy datasets per image-set (with clinically realistic noise levels) using an XCAT anthropomorphic phantom with liver tumours of varying sizes. These were subsequently reconstructed using the OS-EM algorithm with varying PSF modelled kernels. We focused on quantitation of both SUV mean and SUV max , including assessment of contrast recovery coefficients, as well as noise-bias characteristics (including both image roughness and coefficient of-variability), for different tumours/iterations/PSF kernels. It was observed that overestimated PSF yielded more accurate contrast recovery for a range of tumours, and typically improved quantitative performance. For a clinically reasonable number of iterations, edge enhancement due to PSF modeling (especially due to over-estimated PSF) was in fact seen to lower SUV mean bias in small tumours. Overall, the results indicate that exactly matched PSF modeling does not offer optimized PET quantitation, and that PSF overestimation may provide enhanced SUV quantitation. Furthermore, generalized PSF modeling may provide a valuable approach for quantitative tasks such as treatment-response assessment and prognostication.

Development and validation of a rebinner with rigid motion correction for the Siemens PET-MR scanner: Application to a large cohort of [11C]-PIB scans.

PubMed

Reilhac, Anthonin; Merida, Ines; Irace, Zacharie; Stephenson, Mary; Weekes, Ashley; Chen, Christopher; Totman, John; Townsend, David W; Fayad, Hadi; Costes, Nicolas

2018-04-13

Objective: Head motion occuring during brain PET studies leads to image blurring and to bias in measured local quantities. Our first objective was to implement an accurate list-mode-based rigid motion correction method for PET data acquired with the mMR synchronous Positron Emission Tomography/Magnetic Resonance (PET/MR) scanner. Our second objective was to optimize the correction for [ 11 C]-PIB scans using simulated and actual data with well-controlled motions. Results: An efficient list-mode based motion correction approach has been implemented, fully optimized and validated using simulated as well as actual PET data. The average spatial resolution loss induced by inaccuracies in motion parameter estimates as well as by the rebinning process was estimated to correspond to a 1 mm increase in Full Width Half Maximum (FWHM) with motion parameters estimated directly from the PET data with a temporal frequency of 20 secs. The results show that it can be safely applied to the [ 11 C]-PIB scans, allowing almost complete removal of motion induced artifacts.The application of the correction method on a large cohort of 11C-PIB scans led to the following observations: i) more than 21% of the scans were affected by a motion greater than 10 mm (39% for subjects with Mini-Mental State Examination -MMSE scores below 20) and ii), the correction led to quantitative changes in Alzheimer-specific cortical regions of up to 30%. Conclusion: The rebinner allows an accurate motion correction at a cost of minimal resolution reduction. The application of the correction to a large cohort of [ 11 C]-PIB scans confirmed the necessity to systematically correct for motion for quantitative results. Copyright © 2018 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

The Assessment of Estrogen Receptor Status and Its Intratumoral Heterogeneity in Patients With Breast Cancer by Using 18F-Fluoroestradiol PET/CT.

PubMed

Yang, Zhongyi; Sun, Yifei; Xu, Xiaoping; Zhang, Yongping; Zhang, Jianping; Xue, Jing; Wang, Mingwei; Yuan, Huiyu; Hu, Silong; Shi, Wei; Zhu, Beiling; Zhang, Yingjian

2017-06-01

The aim of this study was to investigate the clinical value of F-fluoroestradiol (F-FES) PET/CT in the assessment of the estrogen receptor (ER) and its intratumoral heterogeneity in breast cancer patients. Forty-six female patients (50 lesions) with histologically confirmed invasive breast cancer who underwent both F-FES and F-FDG PET/CT in our center were retrospectively included. All the patients enrolled were scheduled to undergo biopsy. The F-FES and FDG uptakes were compared with pathological features (tumor size, ER, progesterone receptor, human epidermal growth factor receptor 2, and Ki67%). The optimal threshold to discriminate ER-positive and ER-negative lesions was determined by receiver operating characteristic curve analysis. Furthermore, we observed the intratumoral heterogeneity by a heterogeneity index (SUVmax/SUVmean) and compared the results with the Chang-Gung Image Texture Analysis. There was good agreement between F-FES uptake and ER, progesterone receptor, and human epidermal growth factor receptor 2 expression (P < 0.001), and the use of SUVmean instead of SUVmax can provide a slightly better correlation. The optimal threshold for F-FES PET/CT to discriminate between ER-positive and ER-negative lesions, as determined by receiver operating characteristic curve analysis, was an SUVmax of 1.82 (sensitivity = 88.2% and specificity = 87.5%) and SUVmean of 1.21 (sensitivity = 85.3% and specificity = 93.7). Our simplified heterogeneity index-FES can easily observe ER heterogeneity. In addition, our results suggested that recurrent/metastatic patients and lesions located other than breast might have greater heterogeneity. F-FES PET/CT is a feasible, noninvasive method for assessing ER expression in breast cancer patients. Because intratumoral heterogeneity exists, F-FES PET/CT might better reflect the ER expression, especially in metastatic patients after treatment, thus assisting in making individualized treatment decisions.

Development of an instrument for time activity curve measurements during PET imaging of rodents

NASA Astrophysics Data System (ADS)

Reymond, Jean-Marc; Guez, David; Kerhoas, Sophie; Mangeot, Philippe; Boisgard, Raphaël; Jan, Sébastien; Tavitian, Bertrand; Trebossen, Régine

2007-02-01

Molecular imaging using PET in small rodents requires commonly the knowledge of the input function of the tracer (quantitative and kinetic studies of the metabolism, development of new drugs or new tracers, etc.). In this paper, we report the status and the performances of the prototype of a counting system that is under development at DAPNIA a in collaboration with SHFJ b. The detection device is made of silicon diodes of 0.3 mm thickness proper to measure the positrons emitted by the radiotracer contained in arterial blood flowing in a thin-wall microtube. Such diodes are poorly efficient for the 511 keV gammas from the rodent and thus require a rather light lead shielding and allow operating very close by to the animal. The detectors, the front-end electronics (for signal preamplification, shaping, and discrimination) and the acquisition circuits are mounted on a single card. The device is connected directly to a portable computer via an USB port. Such a design provides a compact, rugged and portable device for working close to a small animal PET camera. Preliminary results show the performances of this counting system with 18F solution and a time-activity curve for FDG blood samples (with ∣˜30 μL/samples) from a rat.

Optimization, evaluation, and comparison of standard algorithms for image reconstruction with the VIP-PET.

PubMed

Mikhaylova, E; Kolstein, M; De Lorenzo, G; Chmeissani, M

2014-07-01

A novel positron emission tomography (PET) scanner design based on a room-temperature pixelated CdTe solid-state detector is being developed within the framework of the Voxel Imaging PET (VIP) Pathfinder project [1]. The simulation results show a great potential of the VIP to produce high-resolution images even in extremely challenging conditions such as the screening of a human head [2]. With unprecedented high channel density (450 channels/cm 3 ) image reconstruction is a challenge. Therefore optimization is needed to find the best algorithm in order to exploit correctly the promising detector potential. The following reconstruction algorithms are evaluated: 2-D Filtered Backprojection (FBP), Ordered Subset Expectation Maximization (OSEM), List-Mode OSEM (LM-OSEM), and the Origin Ensemble (OE) algorithm. The evaluation is based on the comparison of a true image phantom with a set of reconstructed images obtained by each algorithm. This is achieved by calculation of image quality merit parameters such as the bias, the variance and the mean square error (MSE). A systematic optimization of each algorithm is performed by varying the reconstruction parameters, such as the cutoff frequency of the noise filters and the number of iterations. The region of interest (ROI) analysis of the reconstructed phantom is also performed for each algorithm and the results are compared. Additionally, the performance of the image reconstruction methods is compared by calculating the modulation transfer function (MTF). The reconstruction time is also taken into account to choose the optimal algorithm. The analysis is based on GAMOS [3] simulation including the expected CdTe and electronic specifics.

Poster - 03: How to manage a nuclear medicine PET-CT for radiation oncology patients

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hinse, Martin; Létourneau, Étienne; Duplan, Danny

Purpose: Development of an adapted multidisciplinary procedure designed to optimize the clinical workflow between radiation therapy (RT) and nuclear medicine (NM) for a PET-CT located in the NM department. Methods : The radiation oncologist (RO) prescribes the PET-CT exam and the clinical RT therapist gives all the necessary information to the patient prior to the exam. The immobilization accessories are prepared in the RT department. The RT and NM therapists work together for radiotracer injection, patient positioning and scan acquisition. The nuclear medicine physician (NMP) will study the images, draw Biological Target Volumes (BTVs) and produce a full exam report.more » Results : All tasks related to a planning PET-CT are done within 48 hours from the request by the RO to the reception of the images with the NMP contours and report. Conclusions : By developing a complete procedure collectively between the RT and NM departments, the patient benefits of a quick access to a RT planning PET-CT exam including the active involvement of every medical practitioners in these fields.« less

Evaluation of image registration in PET/CT of the liver and recommendations for optimized imaging.

PubMed

Vogel, Wouter V; van Dalen, Jorn A; Wiering, Bas; Huisman, Henkjan; Corstens, Frans H M; Ruers, Theo J M; Oyen, Wim J G

2007-06-01

Multimodality PET/CT of the liver can be performed with an integrated (hybrid) PET/CT scanner or with software fusion of dedicated PET and CT. Accurate anatomic correlation and good image quality of both modalities are important prerequisites, regardless of the applied method. Registration accuracy is influenced by breathing motion differences on PET and CT, which may also have impact on (attenuation correction-related) artifacts, especially in the upper abdomen. The impact of these issues was evaluated for both hybrid PET/CT and software fusion, focused on imaging of the liver. Thirty patients underwent hybrid PET/CT, 20 with CT during expiration breath-hold (EB) and 10 with CT during free breathing (FB). Ten additional patients underwent software fusion of dedicated PET and dedicated expiration breath-hold CT (SF). The image registration accuracy was evaluated at the location of liver borders on CT and uncorrected PET images and at the location of liver lesions. Attenuation-correction artifacts were evaluated by comparison of liver borders on uncorrected and attenuation-corrected PET images. CT images were evaluated for the presence of breathing artifacts. In EB, 40% of patients had an absolute registration error of the diaphragm in the craniocaudal direction of >1 cm (range, -16 to 44 mm), and 45% of lesions were mispositioned >1 cm. In 50% of cases, attenuation-correction artifacts caused a deformation of the liver dome on PET of >1 cm. Poor compliance to breath-hold instructions caused CT artifacts in 55% of cases. In FB, 30% had registration errors of >1 cm (range, -4 to 16 mm) and PET artifacts were less extensive, but all CT images had breathing artifacts. As SF allows independent alignment of PET and CT, no registration errors or artifacts of >1 cm of the diaphragm occurred. Hybrid PET/CT of the liver may have significant registration errors and artifacts related to breathing motion. The extent of these issues depends on the selected breathing protocol and the speed of the CT scanner. No protocol or scanner can guarantee perfect image fusion. On the basis of these findings, recommendations were formulated with regard to scanner requirements, breathing protocols, and reporting.

PET optimization for improved assessment and accurate quantification of {sup 90}Y-microsphere biodistribution after radioembolization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martí-Climent, Josep M., E-mail: jmmartic@unav.es; Prieto, Elena; Elosúa, César

2014-09-15

Purpose: {sup 90}Y-microspheres are widely used for the radioembolization of metastatic liver cancer or hepatocellular carcinoma and there is a growing interest for imaging {sup 90}Y-microspheres with PET. The aim of this study is to evaluate the performance of a current generation PET/CT scanner for {sup 90}Y imaging and to optimize the PET protocol to improve the assessment and the quantification of {sup 90}Y-microsphere biodistribution after radioembolization. Methods: Data were acquired on a Biograph mCT-TrueV scanner with time of flight (TOF) and point spread function (PSF) modeling. Spatial resolution was measured with a{sup 90}Y point source. Sensitivity was evaluated usingmore » the NEMA 70 cm line source filled with {sup 90}Y. To evaluate the count rate performance, {sup 90}Y vials with activity ranging from 3.64 to 0.035 GBq were measured in the center of the field of view (CFOV). The energy spectrum was evaluated. Image quality with different reconstructions was studied using the Jaszczak phantom containing six hollow spheres (diameters: 31.3, 28.1, 21.8, 16.1, 13.3, and 10.5 mm), filled with a 207 kBq/ml {sup 90}Y concentration and a 5:1 sphere-to-background ratio. Acquisition time was adjusted to simulate the quality of a realistic clinical PET acquisition of a patient treated with SIR-Spheres{sup ®}. The developed methodology was applied to ten patients after SIR-Spheres{sup ®} treatment acquiring a 10 min per bed PET. Results: The energy spectrum showed the{sup 90}Y bremsstrahlung radiation. The {sup 90}Y transverse resolution, with filtered backprojection reconstruction, was 4.5 mm in the CFOV and degraded to 5.0 mm at 10 cm off-axis. {sup 90}Y absolute sensitivity was 0.40 kcps/MBq in the center of the field of view. Tendency of true and random rates as a function of the {sup 90}Y activity could be accurately described using linear and quadratic models, respectively. Phantom studies demonstrated that, due to low count statistics in {sup 90}Y PET acquisition, the optimal parameters for the standard OSEM+PSF reconstruction were only one iteration and a postreconstruction filter of 6 mm FWHM, for both TOF and non-TOF reconstructions. Moreover, when TOF is included, the signal to noise ratio increased and visibility achieved 100% by the experienced observers and 93.3% according to the Rose model of statistical detection. In 50% of patients, TOF allowed the visualization of {sup 90}Y radioembolized lesions not seen without TOF, confirming phantom results. Liver activity was accurately quantified, with no significant differences between reconstructed and actual delivered activity to the whole-liver [mean relative difference (10.2 ± 14.7)%]. Conclusions: Qualitative and quantitative{sup 90}Y PET imaging improved with the introduction of TOF in a PET/CT scanner, thereby allowing the visualization of microsphere deposition in lesions not visible in non-TOF images. This technique accurately quantifies the total activity delivered to the liver during radioembolization with {sup 90}Y-microspheres and allows dose estimation.« less

Optimization of the Energy Window for PETbox4, a Preclinical PET Tomograph With a Small Inner Diameter

NASA Astrophysics Data System (ADS)

Gu, Z.; Bao, Q.; Taschereau, R.; Wang, H.; Bai, B.; Chatziioannou, A. F.

2014-06-01

Small animal positron emission tomography (PET) systems are often designed by employing close geometry configurations. Due to the different characteristics caused by geometrical factors, these tomographs require data acquisition protocols that differ from those optimized for conventional large diameter ring systems. In this work we optimized the energy window for data acquisitions with PETbox4, a 50 mm detector separation (box-like geometry) pre-clinical PET scanner, using the Geant4 Application for Tomographic Emission (GATE). The fractions of different types of events were estimated using a voxelized phantom including a mouse as well as its supporting chamber, mimicking a realistic mouse imaging environment. Separate code was developed to extract additional information about the gamma interactions for more accurate event type classification. Three types of detector backscatter events were identified in addition to the trues, phantom scatters and randoms. The energy window was optimized based on the noise equivalent count rate (NECR) and scatter fraction (SF) with lower-level discriminators (LLD) corresponding to energies from 150 keV to 450 keV. The results were validated based on the calculated image uniformity, spillover ratio (SOR) and recovery coefficient (RC) from physical measurements using the National Electrical Manufacturers Association (NEMA) NU-4 image quality phantom. These results indicate that when PETbox4 is operated with a more narrow energy window (350-650 keV), detector backscatter rejection is unnecessary. For the NEMA NU-4 image quality phantom, the SOR for the water chamber decreases by about 45% from 15.1% to 8.3%, and the SOR for the air chamber decreases by 31% from 12.0% to 8.3% at the LLDs of 150 and 350 keV, without obvious change in uniformity, further supporting the simulation based optimization. The optimization described in this work is not limited to PETbox4, but also applicable or helpful to other small inner diameter geometry scanners.

Dynamic whole body PET parametric imaging: II. Task-oriented statistical estimation

PubMed Central

Karakatsanis, Nicolas A.; Lodge, Martin A.; Zhou, Y.; Wahl, Richard L.; Rahmim, Arman

2013-01-01

In the context of oncology, dynamic PET imaging coupled with standard graphical linear analysis has been previously employed to enable quantitative estimation of tracer kinetic parameters of physiological interest at the voxel level, thus, enabling quantitative PET parametric imaging. However, dynamic PET acquisition protocols have been confined to the limited axial field-of-view (~15–20cm) of a single bed position and have not been translated to the whole-body clinical imaging domain. On the contrary, standardized uptake value (SUV) PET imaging, considered as the routine approach in clinical oncology, commonly involves multi-bed acquisitions, but is performed statically, thus not allowing for dynamic tracking of the tracer distribution. Here, we pursue a transition to dynamic whole body PET parametric imaging, by presenting, within a unified framework, clinically feasible multi-bed dynamic PET acquisition protocols and parametric imaging methods. In a companion study, we presented a novel clinically feasible dynamic (4D) multi-bed PET acquisition protocol as well as the concept of whole body PET parametric imaging employing Patlak ordinary least squares (OLS) regression to estimate the quantitative parameters of tracer uptake rate Ki and total blood distribution volume V. In the present study, we propose an advanced hybrid linear regression framework, driven by Patlak kinetic voxel correlations, to achieve superior trade-off between contrast-to-noise ratio (CNR) and mean squared error (MSE) than provided by OLS for the final Ki parametric images, enabling task-based performance optimization. Overall, whether the observer's task is to detect a tumor or quantitatively assess treatment response, the proposed statistical estimation framework can be adapted to satisfy the specific task performance criteria, by adjusting the Patlak correlation-coefficient (WR) reference value. The multi-bed dynamic acquisition protocol, as optimized in the preceding companion study, was employed along with extensive Monte Carlo simulations and an initial clinical FDG patient dataset to validate and demonstrate the potential of the proposed statistical estimation methods. Both simulated and clinical results suggest that hybrid regression in the context of whole-body Patlak Ki imaging considerably reduces MSE without compromising high CNR. Alternatively, for a given CNR, hybrid regression enables larger reductions than OLS in the number of dynamic frames per bed, allowing for even shorter acquisitions of ~30min, thus further contributing to the clinical adoption of the proposed framework. Compared to the SUV approach, whole body parametric imaging can provide better tumor quantification, and can act as a complement to SUV, for the task of tumor detection. PMID:24080994

Dynamic whole-body PET parametric imaging: II. Task-oriented statistical estimation.

PubMed

Karakatsanis, Nicolas A; Lodge, Martin A; Zhou, Y; Wahl, Richard L; Rahmim, Arman

2013-10-21

In the context of oncology, dynamic PET imaging coupled with standard graphical linear analysis has been previously employed to enable quantitative estimation of tracer kinetic parameters of physiological interest at the voxel level, thus, enabling quantitative PET parametric imaging. However, dynamic PET acquisition protocols have been confined to the limited axial field-of-view (~15-20 cm) of a single-bed position and have not been translated to the whole-body clinical imaging domain. On the contrary, standardized uptake value (SUV) PET imaging, considered as the routine approach in clinical oncology, commonly involves multi-bed acquisitions, but is performed statically, thus not allowing for dynamic tracking of the tracer distribution. Here, we pursue a transition to dynamic whole-body PET parametric imaging, by presenting, within a unified framework, clinically feasible multi-bed dynamic PET acquisition protocols and parametric imaging methods. In a companion study, we presented a novel clinically feasible dynamic (4D) multi-bed PET acquisition protocol as well as the concept of whole-body PET parametric imaging employing Patlak ordinary least squares (OLS) regression to estimate the quantitative parameters of tracer uptake rate Ki and total blood distribution volume V. In the present study, we propose an advanced hybrid linear regression framework, driven by Patlak kinetic voxel correlations, to achieve superior trade-off between contrast-to-noise ratio (CNR) and mean squared error (MSE) than provided by OLS for the final Ki parametric images, enabling task-based performance optimization. Overall, whether the observer's task is to detect a tumor or quantitatively assess treatment response, the proposed statistical estimation framework can be adapted to satisfy the specific task performance criteria, by adjusting the Patlak correlation-coefficient (WR) reference value. The multi-bed dynamic acquisition protocol, as optimized in the preceding companion study, was employed along with extensive Monte Carlo simulations and an initial clinical (18)F-deoxyglucose patient dataset to validate and demonstrate the potential of the proposed statistical estimation methods. Both simulated and clinical results suggest that hybrid regression in the context of whole-body Patlak Ki imaging considerably reduces MSE without compromising high CNR. Alternatively, for a given CNR, hybrid regression enables larger reductions than OLS in the number of dynamic frames per bed, allowing for even shorter acquisitions of ~30 min, thus further contributing to the clinical adoption of the proposed framework. Compared to the SUV approach, whole-body parametric imaging can provide better tumor quantification, and can act as a complement to SUV, for the task of tumor detection.

Experimental verification of a 4D MLEM reconstruction algorithm used for in-beam PET measurements in particle therapy

NASA Astrophysics Data System (ADS)

Stützer, K.; Bert, C.; Enghardt, W.; Helmbrecht, S.; Parodi, K.; Priegnitz, M.; Saito, N.; Fiedler, F.

2013-08-01

In-beam positron emission tomography (PET) has been proven to be a reliable technique in ion beam radiotherapy for the in situ and non-invasive evaluation of the correct dose deposition in static tumour entities. In the presence of intra-fractional target motion an appropriate time-resolved (four-dimensional, 4D) reconstruction algorithm has to be used to avoid reconstructed activity distributions suffering from motion-related blurring artefacts and to allow for a dedicated dose monitoring. Four-dimensional reconstruction algorithms from diagnostic PET imaging that can properly handle the typically low counting statistics of in-beam PET data have been adapted and optimized for the characteristics of the double-head PET scanner BASTEI installed at GSI Helmholtzzentrum Darmstadt, Germany (GSI). Systematic investigations with moving radioactive sources demonstrate the more effective reduction of motion artefacts by applying a 4D maximum likelihood expectation maximization (MLEM) algorithm instead of the retrospective co-registration of phasewise reconstructed quasi-static activity distributions. Further 4D MLEM results are presented from in-beam PET measurements of irradiated moving phantoms which verify the accessibility of relevant parameters for the dose monitoring of intra-fractionally moving targets. From in-beam PET listmode data sets acquired together with a motion surrogate signal, valuable images can be generated by the 4D MLEM reconstruction for different motion patterns and motion-compensated beam delivery techniques.

Theoretical Analysis of Penalized Maximum-Likelihood Patlak Parametric Image Reconstruction in Dynamic PET for Lesion Detection.

PubMed

Yang, Li; Wang, Guobao; Qi, Jinyi

2016-04-01

Detecting cancerous lesions is a major clinical application of emission tomography. In a previous work, we studied penalized maximum-likelihood (PML) image reconstruction for lesion detection in static PET. Here we extend our theoretical analysis of static PET reconstruction to dynamic PET. We study both the conventional indirect reconstruction and direct reconstruction for Patlak parametric image estimation. In indirect reconstruction, Patlak parametric images are generated by first reconstructing a sequence of dynamic PET images, and then performing Patlak analysis on the time activity curves (TACs) pixel-by-pixel. In direct reconstruction, Patlak parametric images are estimated directly from raw sinogram data by incorporating the Patlak model into the image reconstruction procedure. PML reconstruction is used in both the indirect and direct reconstruction methods. We use a channelized Hotelling observer (CHO) to assess lesion detectability in Patlak parametric images. Simplified expressions for evaluating the lesion detectability have been derived and applied to the selection of the regularization parameter value to maximize detection performance. The proposed method is validated using computer-based Monte Carlo simulations. Good agreements between the theoretical predictions and the Monte Carlo results are observed. Both theoretical predictions and Monte Carlo simulation results show the benefit of the indirect and direct methods under optimized regularization parameters in dynamic PET reconstruction for lesion detection, when compared with the conventional static PET reconstruction.

Unsupervised consensus cluster analysis of [18F]-fluoroethyl-L-tyrosine positron emission tomography identified textural features for the diagnosis of pseudoprogression in high-grade glioma.

PubMed

Kebir, Sied; Khurshid, Zain; Gaertner, Florian C; Essler, Markus; Hattingen, Elke; Fimmers, Rolf; Scheffler, Björn; Herrlinger, Ulrich; Bundschuh, Ralph A; Glas, Martin

2017-01-31

Timely detection of pseudoprogression (PSP) is crucial for the management of patients with high-grade glioma (HGG) but remains difficult. Textural features of O-(2-[18F]fluoroethyl)-L-tyrosine positron emission tomography (FET-PET) mirror tumor uptake heterogeneity; some of them may be associated with tumor progression. Fourteen patients with HGG and suspected of PSP underwent FET-PET imaging. A set of 19 conventional and textural FET-PET features were evaluated and subjected to unsupervised consensus clustering. The final diagnosis of true progression vs. PSP was based on follow-up MRI using RANO criteria. Three robust clusters have been identified based on 10 predominantly textural FET-PET features. None of the patients with PSP fell into cluster 2, which was associated with high values for textural FET-PET markers of uptake heterogeneity. Three out of 4 patients with PSP were assigned to cluster 3 that was largely associated with low values of textural FET-PET features. By comparison, tumor-to-normal brain ratio (TNRmax) at the optimal cutoff 2.1 was less predictive of PSP (negative predictive value 57% for detecting true progression, p=0.07 vs. 75% with cluster 3, p=0.04). Clustering based on textural O-(2-[18F]fluoroethyl)-L-tyrosine PET features may provide valuable information in assessing the elusive phenomenon of pseudoprogression.

The NETPET Score: Combining FDG and Somatostatin Receptor Imaging for Optimal Management of Patients with Metastatic Well-Differentiated Neuroendocrine Tumors.

PubMed

Hindié, Elif

2017-01-01

Neuroendocrine tumors (NET) are often metastatic at the time of diagnosis. Metastatic well-differentiated (G1/G2) NET may display a wide range of behaviors, ranging from indolent to aggressive, even within apparently homogeneous categories. Thus, selecting the optimal treatment strategy is a challenging task. Somatostatin receptor imaging (SRI) is the standard molecular imaging technique for well-differentiated NET. When performed with 68 Ga-labeled somatostatin analogs (SRI-PET), it offers exquisite sensitivity for disease staging. SRI is also a prerequisite for using targeted radionuclide therapy (e.g. 177 Lu-DOTATATE). 18F-FDG imaging has traditionally been reserved for staging poorly-differentiated G3 neuroendocrine carcinomas. However, recent data showed that FDG imaging has prognostic value in patients with well-differentiated NET: high uptake was associated with an increased risk of early progression while low uptake suggested an indolent tumor. In this issue of the Journal, Chan and colleagues propose a grading system where the results from the combined reading of SRI-PET and FDG-PET are reported as a single parameter, the "NETPET" score. While the scoring system still needs validation, it is clear that time has come to think about FDG and SRI in metastatic NET not as competitors but as complementary imaging modalities. Dual-tracer imaging can be viewed as a way to characterize disease phenotype in the whole-body. Moving from the prognostic value of dual-tracer imaging to a tool that allows for individualized management would require prospective trials. This editorial will argue that dual-tracer FDG-PET and SRI-PET might influence management of patients with well-differentiated metastatic NET and help selecting between different therapy options.

Simultaneous Calibration: A Joint Optimization Approach for Multiple Kinect and External Cameras.

PubMed

Liao, Yajie; Sun, Ying; Li, Gongfa; Kong, Jianyi; Jiang, Guozhang; Jiang, Du; Cai, Haibin; Ju, Zhaojie; Yu, Hui; Liu, Honghai

2017-06-24

Camera calibration is a crucial problem in many applications, such as 3D reconstruction, structure from motion, object tracking and face alignment. Numerous methods have been proposed to solve the above problem with good performance in the last few decades. However, few methods are targeted at joint calibration of multi-sensors (more than four devices), which normally is a practical issue in the real-time systems. In this paper, we propose a novel method and a corresponding workflow framework to simultaneously calibrate relative poses of a Kinect and three external cameras. By optimizing the final cost function and adding corresponding weights to the external cameras in different locations, an effective joint calibration of multiple devices is constructed. Furthermore, the method is tested in a practical platform, and experiment results show that the proposed joint calibration method can achieve a satisfactory performance in a project real-time system and its accuracy is higher than the manufacturer's calibration.

Simultaneous Calibration: A Joint Optimization Approach for Multiple Kinect and External Cameras

PubMed Central

Liao, Yajie; Sun, Ying; Li, Gongfa; Kong, Jianyi; Jiang, Guozhang; Jiang, Du; Cai, Haibin; Ju, Zhaojie; Yu, Hui; Liu, Honghai

2017-01-01

Camera calibration is a crucial problem in many applications, such as 3D reconstruction, structure from motion, object tracking and face alignment. Numerous methods have been proposed to solve the above problem with good performance in the last few decades. However, few methods are targeted at joint calibration of multi-sensors (more than four devices), which normally is a practical issue in the real-time systems. In this paper, we propose a novel method and a corresponding workflow framework to simultaneously calibrate relative poses of a Kinect and three external cameras. By optimizing the final cost function and adding corresponding weights to the external cameras in different locations, an effective joint calibration of multiple devices is constructed. Furthermore, the method is tested in a practical platform, and experiment results show that the proposed joint calibration method can achieve a satisfactory performance in a project real-time system and its accuracy is higher than the manufacturer’s calibration. PMID:28672823

Theory of mind in dogs: is the perspective-taking task a good test?

PubMed

Roberts, William A; Macpherson, Krista

2011-12-01

Udell, Dorey, and Wynne (in press) have reported an experiment in which wolves, shelter dogs, and pet dogs all showed a significant preference for begging from a person who faced them (seer) over a person whose back was turned to them (blind experimenter). On tests with the blind person's eyes covered with a bucket, a book, or a camera, pet dogs showed more preference for the seer than did wolves and shelter dogs. We agree with the authors' position that most of these findings are best explained by preexperimental learning experienced by the subjects. We argue, however, that the perspective-taking task is not a good test of the domestication theory or of the theory of mind in dogs. The problem we see is that use of the perspective-taking task, combined with preexperimental learning in all the subjects, strongly biases the outcome in favor of a behavioral learning interpretation. Tasks less influenced by preexperimental training would provide less confounded tests of domestication and theory of mind.

Dynamic whole-body PET parametric imaging: I. Concept, acquisition protocol optimization and clinical application.

PubMed

Karakatsanis, Nicolas A; Lodge, Martin A; Tahari, Abdel K; Zhou, Y; Wahl, Richard L; Rahmim, Arman

2013-10-21

Static whole-body PET/CT, employing the standardized uptake value (SUV), is considered the standard clinical approach to diagnosis and treatment response monitoring for a wide range of oncologic malignancies. Alternative PET protocols involving dynamic acquisition of temporal images have been implemented in the research setting, allowing quantification of tracer dynamics, an important capability for tumor characterization and treatment response monitoring. Nonetheless, dynamic protocols have been confined to single-bed-coverage limiting the axial field-of-view to ~15-20 cm, and have not been translated to the routine clinical context of whole-body PET imaging for the inspection of disseminated disease. Here, we pursue a transition to dynamic whole-body PET parametric imaging, by presenting, within a unified framework, clinically feasible multi-bed dynamic PET acquisition protocols and parametric imaging methods. We investigate solutions to address the challenges of: (i) long acquisitions, (ii) small number of dynamic frames per bed, and (iii) non-invasive quantification of kinetics in the plasma. In the present study, a novel dynamic (4D) whole-body PET acquisition protocol of ~45 min total length is presented, composed of (i) an initial 6 min dynamic PET scan (24 frames) over the heart, followed by (ii) a sequence of multi-pass multi-bed PET scans (six passes × seven bed positions, each scanned for 45 s). Standard Patlak linear graphical analysis modeling was employed, coupled with image-derived plasma input function measurements. Ordinary least squares Patlak estimation was used as the baseline regression method to quantify the physiological parameters of tracer uptake rate Ki and total blood distribution volume V on an individual voxel basis. Extensive Monte Carlo simulation studies, using a wide set of published kinetic FDG parameters and GATE and XCAT platforms, were conducted to optimize the acquisition protocol from a range of ten different clinically acceptable sampling schedules examined. The framework was also applied to six FDG PET patient studies, demonstrating clinical feasibility. Both simulated and clinical results indicated enhanced contrast-to-noise ratios (CNRs) for Ki images in tumor regions with notable background FDG concentration, such as the liver, where SUV performed relatively poorly. Overall, the proposed framework enables enhanced quantification of physiological parameters across the whole body. In addition, the total acquisition length can be reduced from 45 to ~35 min and still achieve improved or equivalent CNR compared to SUV, provided the true Ki contrast is sufficiently high. In the follow-up companion paper, a set of advanced linear regression schemes is presented to particularly address the presence of noise, and attempt to achieve a better trade-off between the mean-squared error and the CNR metrics, resulting in enhanced task-based imaging.

Dynamic whole body PET parametric imaging: I. Concept, acquisition protocol optimization and clinical application

PubMed Central

Karakatsanis, Nicolas A.; Lodge, Martin A.; Tahari, Abdel K.; Zhou, Y.; Wahl, Richard L.; Rahmim, Arman

2013-01-01

Static whole body PET/CT, employing the standardized uptake value (SUV), is considered the standard clinical approach to diagnosis and treatment response monitoring for a wide range of oncologic malignancies. Alternative PET protocols involving dynamic acquisition of temporal images have been implemented in the research setting, allowing quantification of tracer dynamics, an important capability for tumor characterization and treatment response monitoring. Nonetheless, dynamic protocols have been confined to single bed-coverage limiting the axial field-of-view to ~15–20 cm, and have not been translated to the routine clinical context of whole-body PET imaging for the inspection of disseminated disease. Here, we pursue a transition to dynamic whole body PET parametric imaging, by presenting, within a unified framework, clinically feasible multi-bed dynamic PET acquisition protocols and parametric imaging methods. We investigate solutions to address the challenges of: (i) long acquisitions, (ii) small number of dynamic frames per bed, and (iii) non-invasive quantification of kinetics in the plasma. In the present study, a novel dynamic (4D) whole body PET acquisition protocol of ~45min total length is presented, composed of (i) an initial 6-min dynamic PET scan (24 frames) over the heart, followed by (ii) a sequence of multi-pass multi-bed PET scans (6 passes x 7 bed positions, each scanned for 45sec). Standard Patlak linear graphical analysis modeling was employed, coupled with image-derived plasma input function measurements. Ordinary least squares (OLS) Patlak estimation was used as the baseline regression method to quantify the physiological parameters of tracer uptake rate Ki and total blood distribution volume V on an individual voxel basis. Extensive Monte Carlo simulation studies, using a wide set of published kinetic FDG parameters and GATE and XCAT platforms, were conducted to optimize the acquisition protocol from a range of 10 different clinically acceptable sampling schedules examined. The framework was also applied to six FDG PET patient studies, demonstrating clinical feasibility. Both simulated and clinical results indicated enhanced contrast-to-noise ratios (CNRs) for Ki images in tumor regions with notable background FDG concentration, such as the liver, where SUV performed relatively poorly. Overall, the proposed framework enables enhanced quantification of physiological parameters across the whole-body. In addition, the total acquisition length can be reduced from 45min to ~35min and still achieve improved or equivalent CNR compared to SUV, provided the true Ki contrast is sufficiently high. In the follow-up companion paper, a set of advanced linear regression schemes is presented to particularly address the presence of noise, and attempt to achieve a better trade-off between the mean-squared error (MSE) and the CNR metrics, resulting in enhanced task-based imaging. PMID:24080962

Dynamic whole-body PET parametric imaging: I. Concept, acquisition protocol optimization and clinical application

NASA Astrophysics Data System (ADS)

Karakatsanis, Nicolas A.; Lodge, Martin A.; Tahari, Abdel K.; Zhou, Y.; Wahl, Richard L.; Rahmim, Arman

2013-10-01

Static whole-body PET/CT, employing the standardized uptake value (SUV), is considered the standard clinical approach to diagnosis and treatment response monitoring for a wide range of oncologic malignancies. Alternative PET protocols involving dynamic acquisition of temporal images have been implemented in the research setting, allowing quantification of tracer dynamics, an important capability for tumor characterization and treatment response monitoring. Nonetheless, dynamic protocols have been confined to single-bed-coverage limiting the axial field-of-view to ˜15-20 cm, and have not been translated to the routine clinical context of whole-body PET imaging for the inspection of disseminated disease. Here, we pursue a transition to dynamic whole-body PET parametric imaging, by presenting, within a unified framework, clinically feasible multi-bed dynamic PET acquisition protocols and parametric imaging methods. We investigate solutions to address the challenges of: (i) long acquisitions, (ii) small number of dynamic frames per bed, and (iii) non-invasive quantification of kinetics in the plasma. In the present study, a novel dynamic (4D) whole-body PET acquisition protocol of ˜45 min total length is presented, composed of (i) an initial 6 min dynamic PET scan (24 frames) over the heart, followed by (ii) a sequence of multi-pass multi-bed PET scans (six passes × seven bed positions, each scanned for 45 s). Standard Patlak linear graphical analysis modeling was employed, coupled with image-derived plasma input function measurements. Ordinary least squares Patlak estimation was used as the baseline regression method to quantify the physiological parameters of tracer uptake rate Ki and total blood distribution volume V on an individual voxel basis. Extensive Monte Carlo simulation studies, using a wide set of published kinetic FDG parameters and GATE and XCAT platforms, were conducted to optimize the acquisition protocol from a range of ten different clinically acceptable sampling schedules examined. The framework was also applied to six FDG PET patient studies, demonstrating clinical feasibility. Both simulated and clinical results indicated enhanced contrast-to-noise ratios (CNRs) for Ki images in tumor regions with notable background FDG concentration, such as the liver, where SUV performed relatively poorly. Overall, the proposed framework enables enhanced quantification of physiological parameters across the whole body. In addition, the total acquisition length can be reduced from 45 to ˜35 min and still achieve improved or equivalent CNR compared to SUV, provided the true Ki contrast is sufficiently high. In the follow-up companion paper, a set of advanced linear regression schemes is presented to particularly address the presence of noise, and attempt to achieve a better trade-off between the mean-squared error and the CNR metrics, resulting in enhanced task-based imaging.

A novel optically transparent RF shielding for fully integrated PET/MRI systems

NASA Astrophysics Data System (ADS)

Parl, C.; Kolb, A.; Schmid, A. M.; Wehrl, H. F.; Disselhorst, J. A.; Soubiran, P. D.; Stricker-Shaver, D.; Pichler, B. J.

2017-09-01

Preclinical imaging benefits from simultaneous acquisition of high-resolution anatomical and molecular data. Additionally, PET/MRI systems can provide functional PET and functional MRI data. To optimize PET sensitivity, we propose a system design that fully integrates the MRI coil into the PET system. This allows positioning the scintillators near the object but requires an optimized design of the MRI coil and PET detector. It further requires a new approach in realizing the radiofrequency (RF) shielding. Thus, we propose the use of an optically transparent RF shielding material between the PET scintillator and the light sensor, suppressing the interference between both systems. We evaluated two conductive foils (ITO, 9900) and a wire mesh. The PET performance was tested on a dual-layer scintillator consisting of 12  ×  12 LSO matrices, shifted by half a pitch. The pixel size was 0.9  ×  0.9 mm2 the lengths were 10.0 mm and 5.0 mm, respectively. For a light sensor, we used a 4  ×  4 SiPM array. The RF attenuation was measured from 320 kHz to 420 MHz using two pick-up coils. MRI-compatibility and shielding effect of the materials were evaluated with an MRI system. The average FWHM energy resolution at 511 keV of all 144 crystals of the layer next to the SiPM was deteriorated from 15.73  ±  0.24% to 16.32  ±  0.13%, 16.60  ±  0.25%, and 19.16  ±  0.21% by the ITO foil, 9900 foil, mesh material, respectively. The average peak-to-valley ratio of the PET detector changed from 5.77  ±  0.29 to 4.50  ±  0.39, 4.78  ±  0.48, 3.62  ±  0.16, respectively. The ITO, 9900, mesh attenuated the scintillation light by 11.3  ±  1.6%, 11.0  ±  1.8%, 54.3  ±  0.4%, respectively. To attenuate the RF from 20 MHz to 200 MHz, mesh performed better than copper. The results show that an RF shielding material that is sufficiently transparent for scintillation light and is MRI compatible can be obtained. This result enables the development of a fully integrated PET detector and MRI coil assembly.

Optimization of camera exposure durations for multi-exposure speckle imaging of the microcirculation

PubMed Central

Kazmi, S. M. Shams; Balial, Satyajit; Dunn, Andrew K.

2014-01-01

Improved Laser Speckle Contrast Imaging (LSCI) blood flow analyses that incorporate inverse models of the underlying laser-tissue interaction have been used to develop more quantitative implementations of speckle flowmetry such as Multi-Exposure Speckle Imaging (MESI). In this paper, we determine the optimal camera exposure durations required for obtaining flow information with comparable accuracy with the prevailing MESI implementation utilized in recent in vivo rodent studies. A looping leave-one-out (LOO) algorithm was used to identify exposure subsets which were analyzed for accuracy against flows obtained from analysis with the original full exposure set over 9 animals comprising n = 314 regional flow measurements. From the 15 original exposures, 6 exposures were found using the LOO process to provide comparable accuracy, defined as being no more than 10% deviant, with the original flow measurements. The optimal subset of exposures provides a basis set of camera durations for speckle flowmetry studies of the microcirculation and confers a two-fold faster acquisition rate and a 28% reduction in processing time without sacrificing accuracy. Additionally, the optimization process can be used to identify further reductions in the exposure subsets for tailoring imaging over less expansive flow distributions to enable even faster imaging. PMID:25071956

Characterization of Disease-Related Covariance Topographies with SSMPCA Toolbox: Effects of Spatial Normalization and PET Scanners

PubMed Central

Peng, Shichun; Ma, Yilong; Spetsieris, Phoebe G; Mattis, Paul; Feigin, Andrew; Dhawan, Vijay; Eidelberg, David

2013-01-01

In order to generate imaging biomarkers from disease-specific brain networks, we have implemented a general toolbox to rapidly perform scaled subprofile modeling (SSM) based on principal component analysis (PCA) on brain images of patients and normals. This SSMPCA toolbox can define spatial covariance patterns whose expression in individual subjects can discriminate patients from controls or predict behavioral measures. The technique may depend on differences in spatial normalization algorithms and brain imaging systems. We have evaluated the reproducibility of characteristic metabolic patterns generated by SSMPCA in patients with Parkinson's disease (PD). We used [18F]fluorodeoxyglucose PET scans from PD patients and normal controls. Motor-related (PDRP) and cognition-related (PDCP) metabolic patterns were derived from images spatially normalized using four versions of SPM software (spm99, spm2, spm5 and spm8). Differences between these patterns and subject scores were compared across multiple independent groups of patients and control subjects. These patterns and subject scores were highly reproducible with different normalization programs in terms of disease discrimination and cognitive correlation. Subject scores were also comparable in PD patients imaged across multiple PET scanners. Our findings confirm a very high degree of consistency among brain networks and their clinical correlates in PD using images normalized in four different SPM platforms. SSMPCA toolbox can be used reliably for generating disease-specific imaging biomarkers despite the continued evolution of image preprocessing software in the neuroimaging community. Network expressions can be quantified in individual patients independent of different physical characteristics of PET cameras. PMID:23671030

Characterization of disease-related covariance topographies with SSMPCA toolbox: effects of spatial normalization and PET scanners.

PubMed

Peng, Shichun; Ma, Yilong; Spetsieris, Phoebe G; Mattis, Paul; Feigin, Andrew; Dhawan, Vijay; Eidelberg, David

2014-05-01

To generate imaging biomarkers from disease-specific brain networks, we have implemented a general toolbox to rapidly perform scaled subprofile modeling (SSM) based on principal component analysis (PCA) on brain images of patients and normals. This SSMPCA toolbox can define spatial covariance patterns whose expression in individual subjects can discriminate patients from controls or predict behavioral measures. The technique may depend on differences in spatial normalization algorithms and brain imaging systems. We have evaluated the reproducibility of characteristic metabolic patterns generated by SSMPCA in patients with Parkinson's disease (PD). We used [(18) F]fluorodeoxyglucose PET scans from patients with PD and normal controls. Motor-related (PDRP) and cognition-related (PDCP) metabolic patterns were derived from images spatially normalized using four versions of SPM software (spm99, spm2, spm5, and spm8). Differences between these patterns and subject scores were compared across multiple independent groups of patients and control subjects. These patterns and subject scores were highly reproducible with different normalization programs in terms of disease discrimination and cognitive correlation. Subject scores were also comparable in patients with PD imaged across multiple PET scanners. Our findings confirm a very high degree of consistency among brain networks and their clinical correlates in PD using images normalized in four different SPM platforms. SSMPCA toolbox can be used reliably for generating disease-specific imaging biomarkers despite the continued evolution of image preprocessing software in the neuroimaging community. Network expressions can be quantified in individual patients independent of different physical characteristics of PET cameras. Copyright © 2013 Wiley Periodicals, Inc.

Simulating effects of brain atrophy in longitudinal PET imaging with an anthropomorphic brain phantom

NASA Astrophysics Data System (ADS)

Jonasson, L. S.; Axelsson, J.; Riklund, K.; Boraxbekk, C. J.

2017-07-01

In longitudinal positron emission tomography (PET), the presence of volumetric changes over time can lead to an overestimation or underestimation of the true changes in the quantified PET signal due to the partial volume effect (PVE) introduced by the limited spatial resolution of existing PET cameras and reconstruction algorithms. Here, a 3D-printed anthropomorphic brain phantom with attachable striata in three sizes was designed to enable controlled volumetric changes. Using a method to eliminate the non-radioactive plastic wall, and manipulating BP levels by adding different number of events from list-mode acquisitions, we investigated the artificial volume dependence of BP due to PVE, and potential bias arising from varying BP. Comparing multiple reconstruction algorithms we found that a high-resolution ordered-subsets maximization algorithm with spatially variant point-spread function resolution modeling provided the most accurate data. For striatum, the BP changed by 0.08% for every 1% volume change, but for smaller volumes such as the posterior caudate the artificial change in BP was as high as 0.7% per 1% volume change. A simple gross correction for striatal volume is unsatisfactory, as the amplitude of the PVE on the BP differs depending on where in the striatum the change occurred. Therefore, to correctly interpret age-related longitudinal changes in the BP, we must account for volumetric changes also within a structure, rather than across the whole volume. The present 3D-printing technology, combined with the wall removal method, can be implemented to gain knowledge about the predictable bias introduced by the PVE differences in uptake regions of varying shape.

[Optimization of expression conditions and activity identification of hepatocyte-targeting peptide-human endostatin].

PubMed

Ma, Yan; Li, Wei; Li, Xiaobo; Bao, Dongmei; Lu, Jianpei

2016-12-25

To obtain sufficient purified and active fusion protein-hepatocyte-targeting peptide-human endostatin (HTP-rES), we studied the growth curve and the optimal induction timing of BL21/pET21b-HTP-rES. Different conditions of pH value, induction time, induction concentration and induction temperature were optimized by univariate analysis. After washing, refolding and purifying, the activity of fusion protein was identified by flow cytometry and 3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-di-phenytetrazoliumromide (MTT). Results show that the logarithmic growth phase of BL21/pET21b-HTP-rES was from 1.5 h to 3.5 h, the optimum expression conditions were pH 8.0, 0.06 mmol/L IPTG, at 42 ℃ for 5 h. The purity of inclusion bodies was up to 60% after washing. The purity of target protein was more than 95% after refolding and purification. Our findings provide the foundation for further biological activity and drug development.

Novel multimodality segmentation using level sets and Jensen-Rényi divergence

DOE Office of Scientific and Technical Information (OSTI.GOV)

Markel, Daniel, E-mail: daniel.markel@mail.mcgill.ca; Zaidi, Habib; Geneva Neuroscience Center, Geneva University, CH-1205 Geneva

2013-12-15

Purpose: Positron emission tomography (PET) is playing an increasing role in radiotherapy treatment planning. However, despite progress, robust algorithms for PET and multimodal image segmentation are still lacking, especially if the algorithm were extended to image-guided and adaptive radiotherapy (IGART). This work presents a novel multimodality segmentation algorithm using the Jensen-Rényi divergence (JRD) to evolve the geometric level set contour. The algorithm offers improved noise tolerance which is particularly applicable to segmentation of regions found in PET and cone-beam computed tomography. Methods: A steepest gradient ascent optimization method is used in conjunction with the JRD and a level set activemore » contour to iteratively evolve a contour to partition an image based on statistical divergence of the intensity histograms. The algorithm is evaluated using PET scans of pharyngolaryngeal squamous cell carcinoma with the corresponding histological reference. The multimodality extension of the algorithm is evaluated using 22 PET/CT scans of patients with lung carcinoma and a physical phantom scanned under varying image quality conditions. Results: The average concordance index (CI) of the JRD segmentation of the PET images was 0.56 with an average classification error of 65%. The segmentation of the lung carcinoma images had a maximum diameter relative error of 63%, 19.5%, and 14.8% when using CT, PET, and combined PET/CT images, respectively. The estimated maximal diameters of the gross tumor volume (GTV) showed a high correlation with the macroscopically determined maximal diameters, with aR{sup 2} value of 0.85 and 0.88 using the PET and PET/CT images, respectively. Results from the physical phantom show that the JRD is more robust to image noise compared to mutual information and region growing. Conclusions: The JRD has shown improved noise tolerance compared to mutual information for the purpose of PET image segmentation. Presented is a flexible framework for multimodal image segmentation that can incorporate a large number of inputs efficiently for IGART.« less

Novel multimodality segmentation using level sets and Jensen-Rényi divergence.

PubMed

Markel, Daniel; Zaidi, Habib; El Naqa, Issam

2013-12-01

Positron emission tomography (PET) is playing an increasing role in radiotherapy treatment planning. However, despite progress, robust algorithms for PET and multimodal image segmentation are still lacking, especially if the algorithm were extended to image-guided and adaptive radiotherapy (IGART). This work presents a novel multimodality segmentation algorithm using the Jensen-Rényi divergence (JRD) to evolve the geometric level set contour. The algorithm offers improved noise tolerance which is particularly applicable to segmentation of regions found in PET and cone-beam computed tomography. A steepest gradient ascent optimization method is used in conjunction with the JRD and a level set active contour to iteratively evolve a contour to partition an image based on statistical divergence of the intensity histograms. The algorithm is evaluated using PET scans of pharyngolaryngeal squamous cell carcinoma with the corresponding histological reference. The multimodality extension of the algorithm is evaluated using 22 PET/CT scans of patients with lung carcinoma and a physical phantom scanned under varying image quality conditions. The average concordance index (CI) of the JRD segmentation of the PET images was 0.56 with an average classification error of 65%. The segmentation of the lung carcinoma images had a maximum diameter relative error of 63%, 19.5%, and 14.8% when using CT, PET, and combined PET/CT images, respectively. The estimated maximal diameters of the gross tumor volume (GTV) showed a high correlation with the macroscopically determined maximal diameters, with a R(2) value of 0.85 and 0.88 using the PET and PET/CT images, respectively. Results from the physical phantom show that the JRD is more robust to image noise compared to mutual information and region growing. The JRD has shown improved noise tolerance compared to mutual information for the purpose of PET image segmentation. Presented is a flexible framework for multimodal image segmentation that can incorporate a large number of inputs efficiently for IGART.

Multicenter comparison of 18F-FDG and 68Ga-DOTA-peptide PET/CT for pulmonary carcinoid.

PubMed

Lococo, Filippo; Perotti, Germano; Cardillo, Giuseppe; De Waure, Chiara; Filice, Angelina; Graziano, Paolo; Rossi, Giulio; Sgarbi, Giorgio; Stefanelli, Antonella; Giordano, Alessandro; Granone, Pierluigi; Rindi, Guido; Versari, Annibale; Rufini, Vittoria

2015-03-01

The aims of this study were to retrospectively evaluate and compare the detection rate (DR) of 68Ga-DOTA-peptide and 18F-FDG PET/CT in the preoperative workup of patients with pulmonary carcinoid (PC) and to assess the utility of various functional indices obtained with the 2 tracers in predicting the histological characterization of PC, that is, typical versus atypical. Thirty-three consecutive patients with confirmed PC referred for 18F-FDG and 68Ga-DOTA-peptide PET/CT in 2 centers between January 2009 and April 2013 were included. The semiquantitative evaluation included the SUV max, the SUV of the tumor relative to the maximal liver uptake for 18F-FDG (SUV T/L) or the maximal spleen uptake for 68Ga-DOTA-peptides (SUV T/S), the ratio between SUV max of 68Ga-DOTA-peptides PET/CT, and the SUV max of 18F-FDG PET/CT (SUV max ratio). Histology was used as reference standard. Definitive diagnosis consisted of 23 typical carcinoids (TCs) and 10 atypical carcinoids. 18F-FDG PET/CT was positive in 18 cases and negative in 15 (55% DR). 68Ga-DOTA-peptide PET/CT was positive in 26 cases and negative in 7 (79% DR). In the subgroup analysis, 68Ga-DOTA-peptide PET/CT was superior in detecting TC (91% DR; P < 0.001), whereas 18F-FDG PET/CT was superior in detecting atypical carcinoid (100% DR; P = 0.04). The SUV max ratio was the most accurate semiquantitative index in identifying TC. Overall diagnostic performance of PET/CT in detecting PC is optimal when integrating 18F-FDG and 68Ga-DOTA-peptide PET/CT findings. In the subgroup analysis, the SUV max ratio seems to be the most accurate index in predicting TC. Both methods should be performed when PC is suspected or when the histological subtype is undefined.

WE-AB-204-09: Respiratory Motion Correction in 4D-PET by Simultaneous Motion Estimation and Image Reconstruction (SMEIR)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kalantari, F; Wang, J; Li, T

2015-06-15

Purpose: In conventional 4D-PET, images from different frames are reconstructed individually and aligned by registration methods. Two issues with these approaches are: 1) Reconstruction algorithms do not make full use of all projections statistics; and 2) Image registration between noisy images can Result in poor alignment. In this study we investigated the use of simultaneous motion estimation and image reconstruction (SMEIR) method for cone beam CT for motion estimation/correction in 4D-PET. Methods: Modified ordered-subset expectation maximization algorithm coupled with total variation minimization (OSEM- TV) is used to obtain a primary motion-compensated PET (pmc-PET) from all projection data using Demons derivedmore » deformation vector fields (DVFs) as initial. Motion model update is done to obtain an optimal set of DVFs between the pmc-PET and other phases by matching the forward projection of the deformed pmc-PET and measured projections of other phases. Using updated DVFs, OSEM- TV image reconstruction is repeated and new DVFs are estimated based on updated images. 4D XCAT phantom with typical FDG biodistribution and a 10mm diameter tumor was used to evaluate the performance of the SMEIR algorithm. Results: Image quality of 4D-PET is greatly improved by the SMEIR algorithm. When all projections are used to reconstruct a 3D-PET, motion blurring artifacts are present, leading to a more than 5 times overestimation of the tumor size and 54% tumor to lung contrast ratio underestimation. This error reduced to 37% and 20% for post reconstruction registration methods and SMEIR respectively. Conclusion: SMEIR method can be used for motion estimation/correction in 4D-PET. The statistics is greatly improved since all projection data are combined together to update the image. The performance of the SMEIR algorithm for 4D-PET is sensitive to smoothness control parameters in the DVF estimation step.« less

Design and Characterization of a Gradient-Transparent RF Copper Shield for PET Detector Modules in Hybrid MR-PET Imaging

NASA Astrophysics Data System (ADS)

Berneking, Arne; Trinchero, Riccardo; Ha, YongHyun; Finster, Felix; Cerello, Piergiorgio; Lerche, Christoph; Shah, Nadim Jon

2017-05-01

This paper focuses on the design and the characterization of a frequency-selective shield for positron emission tomography (PET) detector modules of hybrid magnetic resonance-PET scanners, where the shielding of the PET cassettes is located close to the observed object. The proposed shielding configuration is designed and optimized to guarantee a high shielding effectiveness (SE) of up to 60 dB for B1-fields at the Larmor frequency of 64 MHz, thus preventing interactions between the radio-frequency (RF) coil and PET electronics. On the other hand, the shield is transparent to the gradient fields with the consequence that eddy-current artifacts in the acquired EPI images are significantly reduced with respect to the standard solid-shield configuration. The frequency-selective behavior of the shield is characterized and validated via simulation studies with CST MICROWAVE STUDIO in the megahertz and kilohertz range. Bench measurements with an RF coil built in-house demonstrated the high SE at the Larmor frequency. Moreover, measurements on a 4-T human scanner confirmed the abolishment of eddy current artifact and also provided an understanding of where the eddy currents occur with respect to the sequence parameters. Simulations and measurements for the proposed shielding concept were compared with a solid copper shielding configuration.

Diagnostic performance of 68Gallium-PSMA-11 PET/CT to detect significant prostate cancer and comparison with 18FEC PET/CT.

PubMed

Hoffmann, Manuela A; Miederer, Matthias; Wieler, Helmut J; Ruf, Christian; Jakobs, Frank M; Schreckenberger, Mathias

2017-12-19

Radiolabeled prostate-specific membrane antigen (PSMA) has proven to be a highly accurate method to detect recurrence and metastases of prostate cancer, but only sparse data is available about its performance in the diagnosis of clinically significant primary prostate cancer. We compared 68 Ga-PSMA-11 PET/CT in 25 patients with 18 FEC PET/CT in 40 patients with suspected prostate carcinoma based on an increased PSA level.The PET/CT results were compared with the histopathologic Gleason Score (GS) of biopsies. The 68 Ga-PSMA-11 PET/CT revealed highly suspect prostatic lesions (maximum standardized uptake value/SUV max >2.5) in 21/25 patients (84%), associated with GS≥6 (low-grade/high-grade carcinoma). Two histopathologic non-malignancy-relevant cases (GS<6) had PSMA-SUV max ≤2.5; all histopathologic high-grade cases (GS≥7b) showed PSMA-SUV max >12.0 which further increased with rising GS. There were 2 false positives and no false negative findings for high-grade prostate cancer using a cut off-level for SUV max of 2.5.In contrast, the 18 FEC PET/CT showed suspected malignant lesions in 38/40 patients (95%), which included 3 lesions with GS<6. The mean SUV max values did not differ with different GS. There were 11 false positives and 1 false negative for detection of high-grade prostate cancer (cut off 2.5).By means of ROC analysis a SUV max of 5.4 was found to be an optimal cut off-level to distinguish between low- and high-grade carcinoma in 68 Ga-PSMA-11 PET/CT (AUC=0.9692; 95% CI 0.9086;1.0000;SD(AUC)=0.0309)). Choosing a cut off-level of SUV max 5.4, 68 Ga-PSMA-11 PET/CT was able to distinguish between GS ≤7a/≥7b with a sensitivity of 84%, a specificity of 100%, a negative predictive value (NPV) of 67%, and an efficiency of 88% ( p <0.001).The ROC analysis revealed a SUV max 6.5 as an optimal cut off-level to distinguish between low- and high-grade carcinoma in 18 FEC PET/CT (AUC=0.7470; 95% CI 0.5919;0.9020;SD(AUC)=0.0791) with a sensitivity of 61% and a specificity of 92%; but the efficiency was only 70% and the NPV 50% ( p =0.01). 68 Ga-PSMA-11 PET/CT guided biopsy of the prostate increases diagnostic precision and is likely to help to reduce overtreatment of low-grade malignant disease as well as detect the foci of the highest Gleason pattern. Both methods ( 68 Ga-PSMA-11, 18 FEC) were suitable to detect primary prostate cancer, but the excellent image quality, the higher specificity and the good correlation of positive scans with GS are advantages of 68 Ga-PSMA-11.

LWIR NUC using an uncooled microbolometer camera

NASA Astrophysics Data System (ADS)

Laveigne, Joe; Franks, Greg; Sparkman, Kevin; Prewarski, Marcus; Nehring, Brian; McHugh, Steve

2010-04-01

Performing a good non-uniformity correction is a key part of achieving optimal performance from an infrared scene projector. Ideally, NUC will be performed in the same band in which the scene projector will be used. Cooled, large format MWIR cameras are readily available and have been successfully used to perform NUC, however, cooled large format LWIR cameras are not as common and are prohibitively expensive. Large format uncooled cameras are far more available and affordable, but present a range of challenges in practical use for performing NUC on an IRSP. Santa Barbara Infrared, Inc. reports progress on a continuing development program to use a microbolometer camera to perform LWIR NUC on an IRSP. Camera instability and temporal response and thermal resolution are the main difficulties. A discussion of processes developed to mitigate these issues follows.

TH-E-BRF-10: Interim Esophageal Cancer Response Assessment Via 18FDG-PET Scanning During Radiation Therapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Higgins, K; Wu, Q; Perez, B

2014-06-15

Purpose: Local failure occurs in a large proportion of esophageal cancer patients treated with chemoradiation. The treatment strategy for non-responders could potentially be modified if they are identified during therapy. This work investigates the utility of an interim 18FDG-PET scan acquired during the course of therapy as a predictor of pathological response post-therapy. Methods: Fifteen patients underwent 18FDG-PET scanning prior to radiation therapy (RT) and once during RT, after delivery of ∼32 Gy. The physician-contoured GTV on the planning CT scan was used to automatically segment a PET-based GTV on the pre-RT PET (GTV-pre-PET) as the volume with >40% ofmore » the maximum GTV PET SUV value. The pre- and intra-RT CTs were deformably registered to each other to transfer the GTV-pre-PET to the intra-RT PET (GTV-intra-PET). The fractional decrease in the maximum SUV, mean SUV and the SUV to the highest intensity 10% – 90% volumes from GTV-pre-PET to GTV-intra-PET were compared to pathological response assessed at the time of post-RT surgery. Results: Based on post-treatment pathology of 15 patients, 7 were classified as achieving favorable response (treatment effect grade ≤ 1) and 8 as unfavorable response (treatment effect grade > 1). Neither fractional decrease in maximum SUV nor mean SUV were significant between the favorable and unfavorable groups. However, the fractional decrease in SUV20% (SUV to the highest 20% volume) was significant (p = 0.02), with an area under the Receiver Operating Characteristics (ROC) curve of 0.84. An optimal cutoff value of 0.46 for this metric was able to distinguish between the two groups with 71% sensitivity (favorable) and 88% specificity (unfavorable). Conclusion: The fractional decrease in SUV to the volume with highest 20% intensity from pre- to intra-RT 18FDG-PET imaging may be used to distinguish between favorable and unfavorable responders with high sensitivity and specificity.« less

SU-C-9A-01: Parameter Optimization in Adaptive Region-Growing for Tumor Segmentation in PET

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tan, S; Huazhong University of Science and Technology, Wuhan, Hubei; Xue, M

Purpose: To design a reliable method to determine the optimal parameter in the adaptive region-growing (ARG) algorithm for tumor segmentation in PET. Methods: The ARG uses an adaptive similarity criterion m - fσ ≤ I-PET ≤ m + fσ, so that a neighboring voxel is appended to the region based on its similarity to the current region. When increasing the relaxing factor f (f ≥ 0), the resulting volumes monotonically increased with a sharp increase when the region just grew into the background. The optimal f that separates the tumor from the background is defined as the first point withmore » the local maximum curvature on an Error function fitted to the f-volume curve. The ARG was tested on a tumor segmentation Benchmark that includes ten lung cancer patients with 3D pathologic tumor volume as ground truth. For comparison, the widely used 42% and 50% SUVmax thresholding, Otsu optimal thresholding, Active Contours (AC), Geodesic Active Contours (GAC), and Graph Cuts (GC) methods were tested. The dice similarity index (DSI), volume error (VE), and maximum axis length error (MALE) were calculated to evaluate the segmentation accuracy. Results: The ARG provided the highest accuracy among all tested methods. Specifically, the ARG has an average DSI, VE, and MALE of 0.71, 0.29, and 0.16, respectively, better than the absolute 42% thresholding (DSI=0.67, VE= 0.57, and MALE=0.23), the relative 42% thresholding (DSI=0.62, VE= 0.41, and MALE=0.23), the absolute 50% thresholding (DSI=0.62, VE=0.48, and MALE=0.21), the relative 50% thresholding (DSI=0.48, VE=0.54, and MALE=0.26), OTSU (DSI=0.44, VE=0.63, and MALE=0.30), AC (DSI=0.46, VE= 0.85, and MALE=0.47), GAC (DSI=0.40, VE= 0.85, and MALE=0.46) and GC (DSI=0.66, VE= 0.54, and MALE=0.21) methods. Conclusions: The results suggest that the proposed method reliably identified the optimal relaxing factor in ARG for tumor segmentation in PET. This work was supported in part by National Cancer Institute Grant R01 CA172638; The dataset is provided by AAPM TG211.« less

Prospective trial evaluating the sensitivity and specificity of 3,4-dihydroxy-6-[18F]-fluoro-L-phenylalanine (18F-DOPA) PET and MRI in patients with recurrent gliomas.

PubMed

Youland, Ryan S; Pafundi, Deanna H; Brinkmann, Debra H; Lowe, Val J; Morris, Jonathan M; Kemp, Bradley J; Hunt, Christopher H; Giannini, Caterina; Parney, Ian F; Laack, Nadia N

2018-05-01

Treatment-related changes can be difficult to differentiate from progressive glioma using MRI with contrast (CE). The purpose of this study is to compare the sensitivity and specificity of 18F-DOPA-PET and MRI in patients with recurrent glioma. Thirteen patients with MRI findings suspicious for recurrent glioma were prospectively enrolled and underwent 18F-DOPA-PET and MRI for neurosurgical planning. Stereotactic biopsies were obtained from regions of concordant and discordant PET and MRI CE, all within regions of T2/FLAIR signal hyperintensity. The sensitivity and specificity of 18F-DOPA-PET and CE were calculated based on histopathologic analysis. Receiver operating characteristic curve analysis revealed optimal tumor to normal (T/N) and SUVmax thresholds. In the 37 specimens obtained, 51% exhibited MRI contrast enhancement (M+) and 78% demonstrated 18F-DOPA-PET avidity (P+). Imaging characteristics included M-P- in 16%, M-P+ in 32%, M+P+ in 46% and M+P- in 5%. Histopathologic review of biopsies revealed grade II components in 16%, grade III in 43%, grade IV in 30% and no tumor in 11%. MRI CE sensitivity for recurrent tumor was 52% and specificity was 50%. PET sensitivity for tumor was 82% and specificity was 50%. A T/N threshold > 2.0 altered sensitivity to 76% and specificity to 100% and SUVmax > 1.36 improved sensitivity and specificity to 94 and 75%, respectively. 18F-DOPA-PET can provide increased sensitivity and specificity compared with MRI CE for visualizing the spatial distribution of recurrent gliomas. Future studies will incorporate 18F-DOPA-PET into re-irradiation target volume delineation for RT planning.

PET/CT scanners: a hardware approach to image fusion.

PubMed

Townsend, David W; Beyer, Thomas; Blodgett, Todd M

2003-07-01

New technology that combines positron tomography with x-ray computed tomography (PET/CT) is available from all major vendors of PET imaging equipment: CTI, Siemens, GE, Philips. Although not all vendors have made the same design choices as those described in this review all have in common that their high performance design places a commercial CT scanner in tandem with a commercial PET scanner. The level of physical integration is actually less than that of the original prototype design where the CT and PET components were mounted on the same rotating support. There will undoubtedly be a demand for PET/CT technology with a greater level of integration, and at a reduced cost. This may be achieved through the design of a scanner specifically for combined anatomical and functional imaging, rather than a design combining separate CT and PET scanners, as in the current approaches. By avoiding the duplication of data acquisition and image reconstruction functions, for example, a more integrated design should also allow cost savings over current commercial PET/CT scanners. The goal is then to design and build a device specifically for imaging the function and anatomy of cancer in the most optimal and effective way, without conceptualizing it as combined PET and CT. The development of devices specifically for imaging a particular disease (eg, cancer) differs from the conventional approach of, for example, an all-purpose anatomical imaging device such as a CT scanner. This new concept targets more of a disease management approach rather than the usual division into the medical specialties of radiology (anatomical imaging) and nuclear medicine (functional imaging). Copyright 2003 Elsevier Inc. All rights reserved.

Eye gaze tracking for endoscopic camera positioning: an application of a hardware/software interface developed to automate Aesop.

PubMed

Ali, S M; Reisner, L A; King, B; Cao, A; Auner, G; Klein, M; Pandya, A K

2008-01-01

A redesigned motion control system for the medical robot Aesop allows automating and programming its movements. An IR eye tracking system has been integrated with this control interface to implement an intelligent, autonomous eye gaze-based laparoscopic positioning system. A laparoscopic camera held by Aesop can be moved based on the data from the eye tracking interface to keep the user's gaze point region at the center of a video feedback monitor. This system setup provides autonomous camera control that works around the surgeon, providing an optimal robotic camera platform.

Ambient Dose Equivalent measured at the Instituto Nacional de Cancerología Department of Nuclear Medicine

NASA Astrophysics Data System (ADS)

Ávila, O.; Torres-Ulloa, C. L.; Medina, L. A.; Trujillo-Zamudio, F. E.; de Buen, I. Gamboa; Buenfil, A. E.; Brandan, M. E.

2010-12-01

Ambient dose equivalent values were determined in several sites at the Instituto Nacional de Cancerología, Departmento de Medicina Nuclear, using TLD-100 and TLD-900 thermoluminescent dosemeters. Additionally, ambient dose equivalent was measured at a corridor outside the hospitalization room for patients treated with 137Cs brachytherapy. Dosemeter calibration was performed at the Instituto Nacional de Investigaciones Nucleares, Laboratorio de Metrología, to known 137Cs gamma radiation air kerma. Radionuclides considered for this study are 131I, 18F, 67Ga, 99mTc, 111In, 201Tl and 137Cs, with main gamma energies between 93 and 662 keV. Dosemeters were placed during a five month period in the nuclear medicine rooms (containing gamma-cameras), injection corridor, patient waiting areas, PET/CT study room, hot lab, waste storage room and corridors next to the hospitalization rooms for patients treated with 131I and 137Cs. High dose values were found at the waste storage room, outside corridor of 137Cs brachytherapy patients and PET/CT area. Ambient dose equivalent rate obtained for the 137Cs brachytherapy corridor is equal to (18.51±0.02)×10-3 mSv/h. Sites with minimum doses are the gamma camera rooms, having ambient dose equivalent rates equal to (0.05±0.03)×10-3 mSv/h. Recommendations have been given to the Department authorities so that further actions are taken to reduce doses at high dose sites in order to comply with the ALARA principle (as low as reasonably achievable).

SU-F-J-06: Optimized Patient Inclusion for NaF PET Response-Based Biopsies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roth, A; Harmon, S; Perk, T

Purpose: A method to guide mid-treatment biopsies using quantitative [F-18]NaF PET/CT response is being investigated in a clinical trial. This study aims to develop methodology to identify patients amenable to mid-treatment biopsy based on pre-treatment imaging characteristics. Methods: 35 metastatic prostate cancer patients had NaF PET/CT scans taken prior to the start of treatment and 9–12 weeks into treatment. For mid-treatment biopsy targeting, lesions must be at least 1.5 cm{sup 3} and located in a clinically feasible region (lumbar/sacral spine, pelvis, humerus, or femur). Three methods were developed based on number of lesions present prior to treatment: a feasibility-restricted method,more » a location-restricted method, and an unrestricted method. The feasibility restricted method only utilizes information from lesions meeting biopsy requirements in the pre-treatment scan. The unrestricted method accounts for all lesions present in the pre-treatment scan. For each method, optimized classification cutoffs for candidate patients were determined. Results: 13 of the 35 patients had enough lesions at the mid-treatment for biopsy candidacy. Of 1749 lesions identified in all 35 patients at mid-treatment, only 9.8% were amenable to biopsy. Optimizing the feasibility-restricted method required 4 lesions at pre-treatment meeting volume and region requirements for biopsy, resulting patient identification sensitivity of 0.8 and specificity of 0.7. Of 6 false positive patients, only one patient lacked lesions for biopsy. Restricting for location alone showed poor results (sensitivity 0.2 and specificity 0.3). The optimized unrestricted method required patients have at least 37 lesions in pretreatment scan, resulting in a sensitivity of 0.8 and specificity of 0.8. There were 5 false positives, only one lacked lesions for biopsy. Conclusion: Incorporating the overall pre-treatment number of NaF PET/CT identified lesions provided best prediction for identifying candidate patients for mid-treatment biopsy. This study provides validity for prediction-based inclusion criteria that can be extended to various clinical trial scenarios. Funded by Prostate Cancer Foundation.« less

Optimization and performance evaluation of the microPET II scanner for in vivo small-animal imaging

NASA Astrophysics Data System (ADS)

Yang, Yongfeng; Tai, Yuan-Chuan; Siegel, Stefan; Newport, Danny F.; Bai, Bing; Li, Quanzheng; Leahy, Richard M.; Cherry, Simon R.

2004-06-01

MicroPET II is a newly developed PET (positron emission tomography) scanner designed for high-resolution imaging of small animals. It consists of 17 640 LSO crystals each measuring 0.975 × 0.975 × 12.5 mm3, which are arranged in 42 contiguous rings, with 420 crystals per ring. The scanner has an axial field of view (FOV) of 4.9 cm and a transaxial FOV of 8.5 cm. The purpose of this study was to carefully evaluate the performance of the system and to optimize settings for in vivo mouse and rat imaging studies. The volumetric image resolution was found to depend strongly on the reconstruction algorithm employed and averaged 1.1 mm (1.4 µl) across the central 3 cm of the transaxial FOV when using a statistical reconstruction algorithm with accurate system modelling. The sensitivity, scatter fraction and noise-equivalent count (NEC) rate for mouse- and rat-sized phantoms were measured for different energy and timing windows. Mouse imaging was optimized with a wide open energy window (150-750 keV) and a 10 ns timing window, leading to a sensitivity of 3.3% at the centre of the FOV and a peak NEC rate of 235 000 cps for a total activity of 80 MBq (2.2 mCi) in the phantom. Rat imaging, due to the higher scatter fraction, and the activity that lies outside of the field of view, achieved a maximum NEC rate of 24 600 cps for a total activity of 80 MBq (2.2 mCi) in the phantom, with an energy window of 250-750 keV and a 6 ns timing window. The sensitivity at the centre of the FOV for these settings is 2.1%. This work demonstrates that different scanner settings are necessary to optimize the NEC count rate for different-sized animals and different injected doses. Finally, phantom and in vivo animal studies are presented to demonstrate the capabilities of microPET II for small-animal imaging studies.

Optimizing Radiometric Fidelity to Enhance Aerial Image Change Detection Utilizing Digital Single Lens Reflex (DSLR) Cameras

NASA Astrophysics Data System (ADS)

Kerr, Andrew D.

Determining optimal imaging settings and best practices related to the capture of aerial imagery using consumer-grade digital single lens reflex (DSLR) cameras, should enable remote sensing scientists to generate consistent, high quality, and low cost image data sets. Radiometric optimization, image fidelity, image capture consistency and repeatability were evaluated in the context of detailed image-based change detection. The impetus for this research is in part, a dearth of relevant, contemporary literature, on the utilization of consumer grade DSLR cameras for remote sensing, and the best practices associated with their use. The main radiometric control settings on a DSLR camera, EV (Exposure Value), WB (White Balance), light metering, ISO, and aperture (f-stop), are variables that were altered and controlled over the course of several image capture missions. These variables were compared for their effects on dynamic range, intra-frame brightness variation, visual acuity, temporal consistency, and the detectability of simulated cracks placed in the images. This testing was conducted from a terrestrial, rather than an airborne collection platform, due to the large number of images per collection, and the desire to minimize inter-image misregistration. The results point to a range of slightly underexposed image exposure values as preferable for change detection and noise minimization fidelity. The makeup of the scene, the sensor, and aerial platform, influence the selection of the aperture and shutter speed which along with other variables, allow for estimation of the apparent image motion (AIM) motion blur in the resulting images. The importance of the image edges in the image application, will in part dictate the lowest usable f-stop, and allow the user to select a more optimal shutter speed and ISO. The single most important camera capture variable is exposure bias (EV), with a full dynamic range, wide distribution of DN values, and high visual contrast and acuity occurring around -0.7 to -0.3EV exposure bias. The ideal values for sensor gain, was found to be ISO 100, with ISO 200 a less desirable. This study offers researchers a better understanding of the effects of camera capture settings on RSI pairs and their influence on image-based change detection.

[Target volume segmentation of PET images by an iterative method based on threshold value].

PubMed

Castro, P; Huerga, C; Glaría, L A; Plaza, R; Rodado, S; Marín, M D; Mañas, A; Serrada, A; Núñez, L

2014-01-01

An automatic segmentation method is presented for PET images based on an iterative approximation by threshold value that includes the influence of both lesion size and background present during the acquisition. Optimal threshold values that represent a correct segmentation of volumes were determined based on a PET phantom study that contained different sizes spheres and different known radiation environments. These optimal values were normalized to background and adjusted by regression techniques to a two-variable function: lesion volume and signal-to-background ratio (SBR). This adjustment function was used to build an iterative segmentation method and then, based in this mention, a procedure of automatic delineation was proposed. This procedure was validated on phantom images and its viability was confirmed by retrospectively applying it on two oncology patients. The resulting adjustment function obtained had a linear dependence with the SBR and was inversely proportional and negative with the volume. During the validation of the proposed method, it was found that the volume deviations respect to its real value and CT volume were below 10% and 9%, respectively, except for lesions with a volume below 0.6 ml. The automatic segmentation method proposed can be applied in clinical practice to tumor radiotherapy treatment planning in a simple and reliable way with a precision close to the resolution of PET images. Copyright © 2013 Elsevier España, S.L.U. and SEMNIM. All rights reserved.

A dual-Kinect approach to determine torso surface motion for respiratory motion correction in PET

DOE Office of Scientific and Technical Information (OSTI.GOV)

Heß, Mirco, E-mail: mirco.hess@uni-muenster.de; Büther, Florian; Dawood, Mohammad

2015-05-15

Purpose: Respiratory gating is commonly used to reduce blurring effects and attenuation correction artifacts in positron emission tomography (PET). Established clinically available methods that employ body-attached hardware for acquiring respiration signals rely on the assumption that external surface motion and internal organ motion are well correlated. In this paper, the authors present a markerless method comprising two Microsoft Kinects for determining the motion on the whole torso surface and aim to demonstrate its validity and usefulness—including the potential to study the external/internal correlation and to provide useful information for more advanced correction approaches. Methods: The data of two Kinects aremore » used to calculate 3D representations of a patient’s torso surface with high spatial coverage. Motion signals can be obtained for any position by tracking the mean distance to a virtual camera with a view perpendicular to the surrounding surface. The authors have conducted validation experiments including volunteers and a moving high-precision platform to verify the method’s suitability for providing meaningful data. In addition, the authors employed it during clinical {sup 18}F-FDG-PET scans and exemplarily analyzed the acquired data of ten cancer patients. External signals of abdominal and thoracic regions as well as data-driven signals were used for gating and compared with respect to detected displacement of present lesions. Additionally, the authors quantified signal similarities and time shifts by analyzing cross-correlation sequences. Results: The authors’ results suggest a Kinect depth resolution of approximately 1 mm at 75 cm distance. Accordingly, valid signals could be obtained for surface movements with small amplitudes in the range of only few millimeters. In this small sample of ten patients, the abdominal signals were better suited for gating the PET data than the thoracic signals and the correlation of data-driven signals was found to be stronger with abdominal signals than with thoracic signals (average Pearson correlation coefficients of 0.74 ± 0.17 and 0.45 ± 0.23, respectively). In all cases, except one, the abdominal respiratory motion preceded the thoracic motion—a maximum delay of approximately 600 ms was detected. Conclusions: The method provides motion information with sufficiently high spatial and temporal resolution. Thus, it enables meaningful analysis in the form of comparisons between amplitudes and phase shifts of signals from different regions. In combination with a large field-of-view, as given by combining the data of two Kinect cameras, it yields surface representations that might be useful in the context of motion correction and motion modeling.« less

Nuclear cardiology practice and associated radiation doses in Europe: results of the IAEA Nuclear Cardiology Protocols Study (INCAPS) for the 27 European countries.

PubMed

Lindner, Oliver; Pascual, Thomas N B; Mercuri, Mathew; Acampa, Wanda; Burchert, Wolfgang; Flotats, Albert; Kaufmann, Philipp A; Kitsiou, Anastasia; Knuuti, Juhani; Underwood, S Richard; Vitola, João V; Mahmarian, John J; Karthikeyan, Ganesan; Better, Nathan; Rehani, Madan M; Kashyap, Ravi; Dondi, Maurizio; Paez, Diana; Einstein, Andrew J

2016-04-01

Nuclear cardiology is widely used to diagnose coronary artery disease and to guide patient management, but data on current practices, radiation dose-related best practices, and radiation doses are scarce. To address these issues, the IAEA conducted a worldwide study of nuclear cardiology practice. We present the European subanalysis. In March 2013, the IAEA invited laboratories across the world to document all SPECT and PET studies performed in one week. The data included age, gender, weight, radiopharmaceuticals, injected activities, camera type, positioning, hardware and software. Radiation effective dose was calculated for each patient. A quality score was defined for each laboratory as the number followed of eight predefined best practices with a bearing on radiation exposure (range of quality score 0 - 8). The participating European countries were assigned to regions (North, East, South, and West). Comparisons were performed between the four European regions and between Europe and the rest-of-the-world (RoW). Data on 2,381 European patients undergoing nuclear cardiology procedures in 102 laboratories in 27 countries were collected. A cardiac SPECT study was performed in 97.9 % of the patients, and a PET study in 2.1 %. The average effective dose of SPECT was 8.0 ± 3.4 mSv (RoW 11.4 ± 4.3 mSv; P < 0.001) and of PET was 2.6 ± 1.5 mSv (RoW 3.8 ± 2.5 mSv; P < 0.001). The mean effective doses of SPECT and PET differed between European regions (P < 0.001 and P = 0.002, respectively). The mean quality score was 6.2 ± 1.2, which was higher than the RoW score (5.0 ± 1.1; P < 0.001). Adherence to best practices did not differ significantly among the European regions (range 6 to 6.4; P = 0.73). Of the best practices, stress-only imaging and weight-adjusted dosing were the least commonly used. In Europe, the mean effective dose from nuclear cardiology is lower and the average quality score is higher than in the RoW. There is regional variation in effective dose in relation to the best practice quality score. A possible reason for the differences between Europe and the RoW could be the safety culture fostered by actions under the Euratom directives and the implementation of diagnostic reference levels. Stress-only imaging and weight-adjusted activity might be targets for optimization of European nuclear cardiology practice.

Clinical Impact of Time-of-Flight and Point Response Modeling in PET Reconstructions: A Lesion Detection Study

PubMed Central

Schaefferkoetter, Joshua; Casey, Michael; Townsend, David; Fakhri, Georges El

2013-01-01

Time-of-flight (TOF) and point spread function (PSF) modeling have been shown to improve PET reconstructions, but the impact on physicians in the clinical setting has not been thoroughly investigated. A lesion detection and localization study was performed using simulated lesions in real patient images. Four reconstruction schemes were considered: ordinary Poisson OSEM (OP) alone and combined with TOF, PSF, and TOF+PSF. The images were presented to physicians experienced in reading PET images, and the performance of each was quantified using localization receiver operating characteristic (LROC). Numerical observers (non-prewhitening and Hotelling) were used to identify optimal reconstruction parameters, and observer SNR was compared to the performance of the physicians. The numerical models showed good agreement with human performance, and best performance was achieved by both when using TOF+PSF. These findings suggest a large potential benefit of TOF+PSF for oncology PET studies, especially in the detection of small, low-intensity, focal disease in larger patients. PMID:23403399

Clinical impact of time-of-flight and point response modeling in PET reconstructions: a lesion detection study

NASA Astrophysics Data System (ADS)

Schaefferkoetter, Joshua; Casey, Michael; Townsend, David; El Fakhri, Georges

2013-03-01

Time-of-flight (TOF) and point spread function (PSF) modeling have been shown to improve PET reconstructions, but the impact on physicians in the clinical setting has not been thoroughly investigated. A lesion detection and localization study was performed using simulated lesions in real patient images. Four reconstruction schemes were considered: ordinary Poisson OSEM (OP) alone and combined with TOF, PSF, and TOF + PSF. The images were presented to physicians experienced in reading PET images, and the performance of each was quantified using localization receiver operating characteristic. Numerical observers (non-prewhitening and Hotelling) were used to identify optimal reconstruction parameters, and observer SNR was compared to the performance of the physicians. The numerical models showed good agreement with human performance, and best performance was achieved by both when using TOF + PSF. These findings suggest a large potential benefit of TOF + PSF for oncology PET studies, especially in the detection of small, low-intensity, focal disease in larger patients.

PET measurements of myocardial blood flow post myocardial infarction: Relationship to invasive and cardiac magnetic resonance studies and potential clinical applications.

PubMed

Gewirtz, Henry

2017-12-01

This review focuses on clinical studies concerning assessment of coronary microvascular and conduit vessel function primarily in the context of acute and sub acute myocardial infarction (MI). The ability of quantitative PET measurements of myocardial blood flow (MBF) to delineate underlying pathophysiology and assist in clinical decision making in this setting is discussed. Likewise, considered are physiological metrics fractional flow reserve, coronary flow reserve, index of microvascular resistance (FFR, CFR, IMR) obtained from invasive studies performed in the cardiac catheterization laboratory, typically at the time of PCI for MI. The role both of invasive studies and cardiac magnetic resonance (CMR) imaging in assessing microvascular function, a key determinant of prognosis, is reviewed. The interface between quantitative PET MBF measurements and underlying pathophysiology, as demonstrated both by invasive and CMR methodology, is discussed in the context of optimal interpretation of the quantitative PET MBF exam and its potential clinical applications.

Development of a center for light ion therapy and accurate tumor diagnostics at karolinska institutet and hospital

NASA Astrophysics Data System (ADS)

Brahme, Anders; Lind, Bengt K.

2002-04-01

Radiation therapy is today in a state of very rapid development with new intensity modulated treatment techniques continuously being developed. This has made intensity modulated electron and photon beams almost as powerful as conventional uniform beam proton therapy. To be able to cure also the most advanced hypoxic and radiation resistant tumors of complex local spread, intensity modulated light ion beams are really the ultimate tool and only slightly more expensive than proton therapy. The aim of the new center for ion therapy and tumor diagnostics in Stockholm is to develop radiobiologically optimized 3-dimensional pencil beam scanning techniques. Beside the "classical" approaches using low ionization density hydrogen ions (protons, but also deuterons and tritium nuclei) and high ionization density carbon ions, two new approaches will be developed. In the first one lithium or beryllium ions, that induce the least detrimental biological effect to normal tissues for a given biological effect in a small volume of the tumor, will be key particles. In the second approach, referred patients will be given a high-dose high-precision "boost" treatment with carbon or oxygen ions during one week preceding the final treatment with conventional radiations in the referring hospital. The rationale behind these approaches is to reduce the high ionization density dose to the normal tissue stroma inside the tumor and to ensure a microscopically uniform dose delivery. The principal idea of the center is to closely integrate ion therapy into the clinical routine and research of a large radiotherapy department. The light ion therapy center will therefore be combined with advanced tumor diagnostics including MR and PET-CT imaging to facilitate efficient high-precision high-dose boost treatment of remitted patients. The possibility to do 3D tumor diagnostics and 3D dose delivery verification with the same PET camera will be the ultimate step in high quality adaptive radiation therapy where alterations in the delivered dose can be corrected by subsequent treatments

Systematic Review on the Accuracy of Positron Emission Tomography/Computed Tomography and Positron Emission Tomography/Magnetic Resonance Imaging in the Management of Ovarian Cancer: Is Functional Information Really Needed?

PubMed Central

Suppiah, Subapriya; Chang, Wing Liong; Hassan, Hasyma Abu; Kaewput, Chalermrat; Asri, Andi Anggeriana Andi; Saad, Fathinul Fikri Ahmad; Nordin, Abdul Jalil; Vinjamuri, Sobhan

2017-01-01

Ovarian cancer (OC) often presents at an advanced stage with frequent relapses despite optimal treatment; thus, accurate staging and restaging are required for improving treatment outcomes and prognostication. Conventionally, staging of OC is performed using contrast-enhanced computed tomography (CT). Nevertheless, recent advances in the field of hybrid imaging have made positron emission tomography/CT (PET/CT) and PET/magnetic resonance imaging (PET/MRI) as emerging potential noninvasive imaging tools for improved management of OC. Several studies have championed the role of PET/CT for the detection of recurrence and prognostication of OC. We provide a systematic review and meta-analysis of the latest publications regarding the role of molecular imaging in the management of OC. We retrieved 57 original research articles with one article having overlap in both diagnosis and staging; 10 articles (734 patients) regarding the role of PET/CT in diagnosis of OC; 12 articles (604 patients) regarding staging of OC; 22 studies (1429 patients) for detection of recurrence; and 13 articles for prognostication and assessment of treatment response. We calculated pooled sensitivity and specificity of PET/CT performance in various aspects of imaging of OC. We also discussed the emerging role of PET/MRI in the management of OC. We aim to give the readers and objective overview on the role of molecular imaging in the management of OC. PMID:28670174

PVC removal from mixed plastics by triboelectrostatic separation.

PubMed

Park, Chul-Hyun; Jeon, Ho-Seok; Park, Jai-Koo

2007-06-01

Ever increasing oil price and the constant growth in generation of waste plastics stimulate a research on material separation for recycling of waste plastics. At present, most waste plastics cause serious environmental problems due to the disposal by reclamation and incineration. Particularly, polyvinyl chloride (PVC) materials among waste plastics generates hazardous HCl gas, dioxins containing Cl, and so on, which lead to air pollution and shorten the life of incinerator, and it makes difficultly recycling of other plastics. Therefore, we designed a bench scale triboelectrostatic separator for PVC removal from mixed plastics (polyvinyl chloride/polyethylene terephthalate), and then carried out material separation tests. In triboelectrostatic separation, PVC and PET particles are charged negatively and positively, respectively, due to the difference of the work function of plastics in tribo charger of the fluidized-bed, and are separated by means of splitter through an opposite electric field. In this study, the charge efficiency of PVC and PET was strongly dependent on the tribo charger material (polypropylene), relative humidity (below 30%), air velocity (over 10 m/s), and mixture ratio (PET:PVC=1:1). At the optimum conditions (electrode potential of 20 kV and splitter position of -2 cm), PVC rejection and PET recovery in PET products were 99.60 and 98.10%, respectively, and the reproducibility of optimal test was very good (+/-1%). In addition, as a change of splitter position, we developed the technique to recover high purity PET (over 99.99%) although PET recovery decreases by degrees.

Applications of immunoPET: Using 124I-anti-PSCA A11 minibody for imaging disease progression and response to therapy in mouse xenograft models of prostate cancer

DOE PAGES

Knowles, Scott M.; Tavare, Richard; Zettlitz, Kirstin A.; ...

2014-10-17

Here, prostate stem cell antigen (PSCA) is highly expressed in local prostate cancers and prostate cancer bone metastases and its expression correlates with androgen receptor activation and a poor prognosis. Here in this study, we investigate the potential clinical applications of immunoPET with the anti-PSCA A11 minibody, an antibody fragment optimized for use as an imaging agent. We compare A11 minibody immunoPET to 18F-Fluoride PET bone scans for detecting prostate cancer bone tumors and evaluate the ability of the A11 minibody to image tumor response to androgen deprivation. Osteoblastic, PSCA expressing, LAPC-9 intratibial xenografts were imaged with serial 124I-anti-PSCA A11more » minibody immunoPET and 18F-Fluoride bone scans. Mice bearing LAPC-9 subcutaneous xenografts were treated with either vehicle or MDV-3100 and imaged with A11 minibody immunoPET/CT scans pre- and post-treatment. Ex vivo flow cytometry measured the change in PSCA expression in response to androgen deprivation. A11 minibody demonstrated improved sensitivity and specificity over 18F-Fluoride bone scans for detecting LAPC-9 intratibial xenografts at all time points. Finally, LAPC-9 subcutaneous xenografts showed downregulation of PSCA when treated with MDV-3100 which A11 minibody immunoPET was able to detect in vivo.« less

Unsupervised consensus cluster analysis of [18F]-fluoroethyl-L-tyrosine positron emission tomography identified textural features for the diagnosis of pseudoprogression in high-grade glioma

PubMed Central

Kebir, Sied; Khurshid, Zain; Gaertner, Florian C.; Essler, Markus; Hattingen, Elke; Fimmers, Rolf; Scheffler, Björn; Herrlinger, Ulrich; Bundschuh, Ralph A.; Glas, Martin

2017-01-01

Rationale Timely detection of pseudoprogression (PSP) is crucial for the management of patients with high-grade glioma (HGG) but remains difficult. Textural features of O-(2-[18F]fluoroethyl)-L-tyrosine positron emission tomography (FET-PET) mirror tumor uptake heterogeneity; some of them may be associated with tumor progression. Methods Fourteen patients with HGG and suspected of PSP underwent FET-PET imaging. A set of 19 conventional and textural FET-PET features were evaluated and subjected to unsupervised consensus clustering. The final diagnosis of true progression vs. PSP was based on follow-up MRI using RANO criteria. Results Three robust clusters have been identified based on 10 predominantly textural FET-PET features. None of the patients with PSP fell into cluster 2, which was associated with high values for textural FET-PET markers of uptake heterogeneity. Three out of 4 patients with PSP were assigned to cluster 3 that was largely associated with low values of textural FET-PET features. By comparison, tumor-to-normal brain ratio (TNRmax) at the optimal cutoff 2.1 was less predictive of PSP (negative predictive value 57% for detecting true progression, p=0.07 vs. 75% with cluster 3, p=0.04). Principal Conclusions Clustering based on textural O-(2-[18F]fluoroethyl)-L-tyrosine PET features may provide valuable information in assessing the elusive phenomenon of pseudoprogression. PMID:28030820

Sensitivity booster for DOI-PET scanner by utilizing Compton scattering events between detector blocks

NASA Astrophysics Data System (ADS)

Yoshida, Eiji; Tashima, Hideaki; Yamaya, Taiga

2014-11-01

In a conventional PET scanner, coincidence events are measured with a limited energy window for detection of photoelectric events in order to reject Compton scatter events that occur in a patient, but Compton scatter events caused in detector crystals are also rejected. Scatter events within the patient causes scatter coincidences, but inter crystal scattering (ICS) events have useful information for determining an activity distribution. Some researchers have reported the feasibility of PET scanners based on a Compton camera for tracing ICS into the detector. However, these scanners require expensive semiconductor detectors for high-energy resolution. In the Anger-type block detector, single photons interacting with multiple detectors can be obtained for each interacting position and complete information can be gotten just as for photoelectric events in the single detector. ICS events in the single detector have been used to get coincidence, but single photons interacting with multiple detectors have not been used to get coincidence. In this work, we evaluated effect of sensitivity improvement using Compton kinetics in several types of DOI-PET scanners. The proposed method promises to improve the sensitivity using coincidence events of single photons interacting with multiple detectors, which are identified as the first interaction (FI). FI estimation accuracy can be improved to determine FI validity from the correlation between Compton scatter angles calculated on the coincidence line-of-response. We simulated an animal PET scanner consisting of 42 detectors. Each detector block consists of three types of scintillator crystals (LSO, GSO and GAGG). After the simulation, coincidence events are added as information for several depth-of-interaction (DOI) resolutions. From the simulation results, we concluded the proposed method promises to improve the sensitivity considerably when effective atomic number of a scintillator is low. Also, we showed that FI estimate accuracy is improved, as DOI resolution is high.

Head motion evaluation and correction for PET scans with 18F-FDG in the Japanese Alzheimer's disease neuroimaging initiative (J-ADNI) multi-center study.

PubMed

Ikari, Yasuhiko; Nishio, Tomoyuki; Makishi, Yoko; Miya, Yukari; Ito, Kengo; Koeppe, Robert A; Senda, Michio

2012-08-01

Head motion during 30-min (six 5-min frames) brain PET scans starting 30 min post-injection of FDG was evaluated together with the effect of post hoc motion correction between frames in J-ADNI multicenter study carried out in 24 PET centers on a total of 172 subjects consisting of 81 normal subjects, 55 mild cognitive impairment (MCI) and 36 mild Alzheimer's disease (AD) patients. Based on the magnitude of the between-frame co-registration parameters, the scans were classified into six levels (A-F) of motion degree. The effect of motion and its correction was evaluated using between-frame variation of the regional FDG uptake values on ROIs placed over cerebral cortical areas. Although AD patients tended to present larger motion (motion level E or F in 22 % of the subjects) than MCI (3 %) and normal (4 %) subjects, unignorable motion was observed in a small number of subjects in the latter groups as well. The between-frame coefficient of variation (SD/mean) was 0.5 % in the frontal, 0.6 % in the parietal and 1.8 % in the posterior cingulate ROI for the scans of motion level 1. The respective values were 1.5, 1.4, and 3.6 % for the scans of motion level F, but reduced by the motion correction to 0.5, 0.4 and 0.8 %, respectively. The motion correction changed the ROI value for the posterior cingulate cortex by 11.6 % in the case of severest motion. Substantial head motion occurs in a fraction of subjects in a multicenter setup which includes PET centers lacking sufficient experience in imaging demented patients. A simple frame-by-frame co-registration technique that can be applied to any PET camera model is effective in correcting for motion and improving quantitative capability.

In vivo PET evaluation in tumour-bearing rats of 2-[ 18F]fluoromethyl- L-phenylalanine as a new potential tracer for molecular imaging of brain and extra-cranial tumours in humans with PET

NASA Astrophysics Data System (ADS)

Kersemans, Ken; Bauwens, Matthias; Lahoutte, Tony; Bossuyt, Axel; Mertens, John

2007-02-01

The Na +-independent L-type LAT1 amino acid transport system for large and neutral amino acids has been shown to be expressed higher in tumour tissue relative to normal tissue and has been regarded as a key point for the development of new amino acid based tumour tracers for molecular imaging. We developed a new fluorinated phenylalanine analogue, 2-[ 18F]fluoromethyl- L-phenylalanine, considering that the spatial volume of FCH 3 is comparable with that of the iodine atom in 2-I- L-phenylalanine, of which we have proven that it is taken up excellently in tumours by the LAT1 system. The substrate molecule for radiolabeling, Boc-2-bromomethyl- L-phenylalanine- tButylester, was prepared by radical bromination of Boc-2-methyl- L-phenylalanine- tButylester. [ 18F -] for bromine exchange is performed within 3 min in conditions comparable to the [ 18F]FDG synthesis with a radiochemical yield of at least 85%. After deprotection and semi-preparative HPLC purification, the 2-[ 18F]fluoromethyl- L-phenylalanine is recovered n.c.a. (57%) with a high purity and 3.7 MBq were injected into R1M rhabdomyosarcoma tumour-bearing rats. Imaging was performed with a human PET camera from 5 to 45 min p.i. The tumour/background and tumour/blood ratios obtained from PET acquisition were at least 2.5. DUR values for the tumours were at least about 5. Furthermore, a small tumour implanted near a kidney could be well visualized completely separated from this kidney. Moreover in all tumours the "active" tumour tissue can clearly be differentiated from less active tumour tissue. This proves that 2-[ 18F]fluoromethyl- L-phenylalanine has a great potential as a new tracer for specific tumour diagnosis with PET.

Demons versus Level-Set motion registration for coronary 18F-sodium fluoride PET.

PubMed

Rubeaux, Mathieu; Joshi, Nikhil; Dweck, Marc R; Fletcher, Alison; Motwani, Manish; Thomson, Louise E; Germano, Guido; Dey, Damini; Berman, Daniel S; Newby, David E; Slomka, Piotr J

2016-02-27

Ruptured coronary atherosclerotic plaques commonly cause acute myocardial infarction. It has been recently shown that active microcalcification in the coronary arteries, one of the features that characterizes vulnerable plaques at risk of rupture, can be imaged using cardiac gated 18 F-sodium fluoride ( 18 F-NaF) PET. We have shown in previous work that a motion correction technique applied to cardiac-gated 18 F-NaF PET images can enhance image quality and improve uptake estimates. In this study, we further investigated the applicability of different algorithms for registration of the coronary artery PET images. In particular, we aimed to compare demons vs. level-set nonlinear registration techniques applied for the correction of cardiac motion in coronary 18 F-NaF PET. To this end, fifteen patients underwent 18 F-NaF PET and prospective coronary CT angiography (CCTA). PET data were reconstructed in 10 ECG gated bins; subsequently these gated bins were registered using demons and level-set methods guided by the extracted coronary arteries from CCTA, to eliminate the effect of cardiac motion on PET images. Noise levels, target-to-background ratios (TBR) and global motion were compared to assess image quality. Compared to the reference standard of using only diastolic PET image (25% of the counts from PET acquisition), cardiac motion registration using either level-set or demons techniques almost halved image noise due to the use of counts from the full PET acquisition and increased TBR difference between 18 F-NaF positive and negative lesions. The demons method produces smoother deformation fields, exhibiting no singularities (which reflects how physically plausible the registration deformation is), as compared to the level-set method, which presents between 4 and 8% of singularities, depending on the coronary artery considered. In conclusion, the demons method produces smoother motion fields as compared to the level-set method, with a motion that is physiologically plausible. Therefore, level-set technique will likely require additional post-processing steps. On the other hand, the observed TBR increases were the highest for the level-set technique. Further investigations of the optimal registration technique of this novel coronary PET imaging technique are warranted.

Demons versus level-set motion registration for coronary 18F-sodium fluoride PET

NASA Astrophysics Data System (ADS)

Rubeaux, Mathieu; Joshi, Nikhil; Dweck, Marc R.; Fletcher, Alison; Motwani, Manish; Thomson, Louise E.; Germano, Guido; Dey, Damini; Berman, Daniel S.; Newby, David E.; Slomka, Piotr J.

2016-03-01

Ruptured coronary atherosclerotic plaques commonly cause acute myocardial infarction. It has been recently shown that active microcalcification in the coronary arteries, one of the features that characterizes vulnerable plaques at risk of rupture, can be imaged using cardiac gated 18F-sodium fluoride (18F-NaF) PET. We have shown in previous work that a motion correction technique applied to cardiac-gated 18F-NaF PET images can enhance image quality and improve uptake estimates. In this study, we further investigated the applicability of different algorithms for registration of the coronary artery PET images. In particular, we aimed to compare demons vs. level-set nonlinear registration techniques applied for the correction of cardiac motion in coronary 18F-NaF PET. To this end, fifteen patients underwent 18F-NaF PET and prospective coronary CT angiography (CCTA). PET data were reconstructed in 10 ECG gated bins; subsequently these gated bins were registered using demons and level-set methods guided by the extracted coronary arteries from CCTA, to eliminate the effect of cardiac motion on PET images. Noise levels, target-to-background ratios (TBR) and global motion were compared to assess image quality. Compared to the reference standard of using only diastolic PET image (25% of the counts from PET acquisition), cardiac motion registration using either level-set or demons techniques almost halved image noise due to the use of counts from the full PET acquisition and increased TBR difference between 18F-NaF positive and negative lesions. The demons method produces smoother deformation fields, exhibiting no singularities (which reflects how physically plausible the registration deformation is), as compared to the level-set method, which presents between 4 and 8% of singularities, depending on the coronary artery considered. In conclusion, the demons method produces smoother motion fields as compared to the level-set method, with a motion that is physiologically plausible. Therefore, level-set technique will likely require additional post-processing steps. On the other hand, the observed TBR increases were the highest for the level-set technique. Further investigations of the optimal registration technique of this novel coronary PET imaging technique are warranted.

Synthesis and radiolabeling of chelator-RNA aptamer bioconjugates with copper-64 for targeted molecular imaging

PubMed Central

Rockey, William M.; Huang, Ling; Kloepping, Kyle C.; Baumhover, Nicholas J.; Giangrande, Paloma H.; Schultz, Michael K.

2014-01-01

Ribonucleic acid (RNA) aptamers with high affinity and specificity for cancer-specific cell-surface antigens are promising reagents for targeted molecular imaging of cancer using positron emission tomography (PET). For this application, aptamers must be conjugated to chelators capable of coordinating PET-radionuclides (e.g. copper-64, 64Cu) to enable radiolabeling for in vivo imaging of tumors. This study investigates the choice of chelator and radiolabeling parameters such as pH and temperature for the development of 64Cu-labeled RNA-based targeted agents for PET imaging. The characterization and optimization of labeling conditions are described for four chelator-aptamer complexes. Three commercially available bifunctional macrocyclic chelators (1,4,7,10-tetraazacyclododecane-1,4,7-triacetic acid mono N-hydroxysuccinimide [DOTA-NHS]; S-2-(4-isothiocyanatobenzyl)-1,4,7-triazacyclononane-1,4,7-triacetic acid [p-SCN-Bn-NOTA]; and p-SCN-Bn-3,6,9,15-tetraazabicyclo [9.3.1]pentadeca-1(15),11,13-triene-3,6,9-triacetic acid [p-SCN-Bn-PCTA]), as well as the polyamino-macrocyclic diAmSar (3,6,10,13,16,19-hexaazabicyclo[6.6.6] icosane-1,8-diamine) were conjugated to A10–3.2, a RNA aptamer which has been shown to bind specifically to a prostate cancer-specific cell-surface antigen (PSMA). Although a commercial bifunctional version of diAmSar was not available, RNA conjugation with this chelator was achieved in a two-step reaction by the addition of a disuccinimidyl suberate linker. Radiolabeling parameters (e.g. pH, temperature, and time) for each chelator-RNA conjugate were assessed in order to optimize specific activity and RNA stability. Furthermore, the radiolabeled chelator-coupled RNA aptamers were evaluated for binding specificity to their target antigen. In summary, key parameters were established for optimal radiolabeling of RNA aptamers for eventual PET imaging with 64Cu. PMID:21658962

Design, optimization and characterization of the light concentrators of the single-mirror small size telescopes of the Cherenkov Telescope Array

NASA Astrophysics Data System (ADS)

Aguilar, J. A.; Basili, A.; Boccone, V.; Cadoux, F.; Christov, A.; della Volpe, D.; Montaruli, T.; Płatos, Ł.; Rameez, M.

2015-01-01

The focal-plane cameras of γ -ray telescopes frequently use light concentrators in front of the light sensors. The purpose of these concentrators is to increase the effective area of the camera as well as to reduce the stray light coming at large incident angles. These light concentrators are usually based on the Winston cone design. In this contribution we present the design of a hexagonal hollow light concentrator with a lateral profile optimized using a cubic Bézier function to achieve a higher collection efficiency in the angular region of interest. The design presented here is optimized for a Davies-Cotton telescope with a primary mirror of about 4 m in diameter and a focal length of 5.6 m. The described concentrators are part of an innovative camera made up of silicon-photomultiplier sensors, although a similar approach can be used for other sizes of single-mirror telescopes with different camera sensors, including photomultipliers. The challenge of our approach is to achieve a cost-effective design suitable for standard industrial production of both the plastic concentrator substrate and the reflective coating. At the same time we maximize the optical performance. In this paper we also describe the optical set-up to measure the absolute collection efficiency of the light concentrators and demonstrate our good understanding of the measured data using a professional ray-tracing simulation.

A new fast and fully automated software based algorithm for extracting respiratory signal from raw PET data and its comparison to other methods.

PubMed

Kesner, Adam Leon; Kuntner, Claudia

2010-10-01

Respiratory gating in PET is an approach used to minimize the negative effects of respiratory motion on spatial resolution. It is based on an initial determination of a patient's respiratory movements during a scan, typically using hardware based systems. In recent years, several fully automated databased algorithms have been presented for extracting a respiratory signal directly from PET data, providing a very practical strategy for implementing gating in the clinic. In this work, a new method is presented for extracting a respiratory signal from raw PET sinogram data and compared to previously presented automated techniques. The acquisition of respiratory signal from PET data in the newly proposed method is based on rebinning the sinogram data into smaller data structures and then analyzing the time activity behavior in the elements of these structures. From this analysis, a 1D respiratory trace is produced, analogous to a hardware derived respiratory trace. To assess the accuracy of this fully automated method, respiratory signal was extracted from a collection of 22 clinical FDG-PET scans using this method, and compared to signal derived from several other software based methods as well as a signal derived from a hardware system. The method presented required approximately 9 min of processing time for each 10 min scan (using a single 2.67 GHz processor), which in theory can be accomplished while the scan is being acquired and therefore allowing a real-time respiratory signal acquisition. Using the mean correlation between the software based and hardware based respiratory traces, the optimal parameters were determined for the presented algorithm. The mean/median/range of correlations for the set of scans when using the optimal parameters was found to be 0.58/0.68/0.07-0.86. The speed of this method was within the range of real-time while the accuracy surpassed the most accurate of the previously presented algorithms. PET data inherently contains information about patient motion; information that is not currently being utilized. We have shown that a respiratory signal can be extracted from raw PET data in potentially real-time and in a fully automated manner. This signal correlates well with hardware based signal for a large percentage of scans, and avoids the efforts and complications associated with hardware. The proposed method to extract a respiratory signal can be implemented on existing scanners and, if properly integrated, can be applied without changes to routine clinical procedures.

SU-D-202-01: Functional Lung Avoidance and Response-Adaptive Escalation (FLARE) RT: Feasibility of a Precision Radiation Oncology Strategy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bowen, S; Lee, E; Miyaoka, R

Purpose: NSCLC patient RT is planned without consideration of spatial heterogeneity in lung function or tumor response, which may have contributed to failed uniform dose escalation in a randomized trial. The feasibility of functional lung avoidance and response-adaptive escalation (FLARE) RT to reduce dose to [{sup 99m}Tc]MAA-SPECT/CT perfused lung while redistributing 74Gy within [{sup 18}F]FDG-PET/CT biological target volumes was assessed. Methods: Eight Stage IIB–IIIB NSCLC patients underwent FDG-PET/CT and MAA-SPECT/CT treatment planning scans. Perfused lung objectives were derived from scatter/collimator/attenuation-corrected MAA-SPECT uptake relative to ITV-subtracted lung to maintain <20Gy mean lung dose (MLD). Prescriptions included 60Gy to PTV and concomitantmore » boost of 74Gy mean to biological target volumes (BTV=GTV+PET margin) scaled to each BTV voxel by relative FDG-PET SUV. Dose-painting-by-numbers prescriptions were integrated into commercial TPS via previously reported ROI discretization. Dose constraints for lung, heart, cord, and esophagus were defined. FLARE RT plans were optimized with VMAT, proton pencil beam scanning (PBS) with 3%-3mm robust optimization, and combination PBS (avoidance) plus VMAT (escalation). Dosimetric differences were evaluated by Friedman non-parametric paired test with multiple sampling correction. Results: PTV and normal tissue objectives were not violated in 24 FLARE RT plans. Population median of mean BTV dose was 73.7Gy (68.5–75.5Gy), mean FDG-PET peak dose was 89.7Gy (73.5–103Gy), MLD was 12.3Gy (7.5–19.6Gy), and perfused MLD was 4.8Gy (0.9–12.1Gy). VMAT achieved higher dose to the FDG-PET peak subvolume (p=0.01), while PBS delivered lower dose to lung (p<0.001). Voxelwise linear correlation between BTV dose and FDG-PET uptake was higher for VMAT (R=0.93) and PBS+VMAT (R=0.94) compared to PBS alone (R=0.89). Conclusion: FLARE RT is feasible with VMAT and PBS. A combination of PBS for functional lung avoidance and VMAT for FDG-PET dose escalation balances target/normal tissue objective tradeoffs. These results support future testing of FLARE RT safety and efficacy within a precision radiation oncology trial. This work was supported by a Research Scholar grant from the Radiological Society of North American Research & Education Foundation.« less

Optimization of a shorter variable-acquisition time for legs to achieve true whole-body PET/CT images.

PubMed

Umeda, Takuro; Miwa, Kenta; Murata, Taisuke; Miyaji, Noriaki; Wagatsuma, Kei; Motegi, Kazuki; Terauchi, Takashi; Koizumi, Mitsuru

2017-12-01

The present study aimed to qualitatively and quantitatively evaluate PET images as a function of acquisition time for various leg sizes, and to optimize a shorter variable-acquisition time protocol for legs to achieve better qualitative and quantitative accuracy of true whole-body PET/CT images. The diameters of legs to be modeled as phantoms were defined based on data derived from 53 patients. This study analyzed PET images of a NEMA phantom and three plastic bottle phantoms (diameter, 5.68, 8.54 and 10.7 cm) that simulated the human body and legs, respectively. The phantoms comprised two spheres (diameters, 10 and 17 mm) containing fluorine-18 fluorodeoxyglucose solution with sphere-to-background ratios of 4 at a background radioactivity level of 2.65 kBq/mL. All PET data were reconstructed with acquisition times ranging from 10 to 180, and 1200 s. We visually evaluated image quality and determined the coefficient of variance (CV) of the background, contrast and the quantitative %error of the hot spheres, and then determined two shorter variable-acquisition protocols for legs. Lesion detectability and quantitative accuracy determined based on maximum standardized uptake values (SUV max ) in PET images of a patient using the proposed protocols were also evaluated. A larger phantom and a shorter acquisition time resulted in increased background noise on images and decreased the contrast in hot spheres. A visual score of ≥ 1.5 was obtained when the acquisition time was ≥ 30 s for three leg phantoms, and ≥ 120 s for the NEMA phantom. The quantitative %errors of the 10- and 17-mm spheres in the leg phantoms were ± 15 and ± 10%, respectively, in PET images with a high CV (scan < 30 s). The mean SUV max of three lesions using the current fixed-acquisition and two proposed variable-acquisition time protocols in the clinical study were 3.1, 3.1 and 3.2, respectively, which did not significantly differ. Leg acquisition time per bed position of even 30-90 s allows axial equalization, uniform image noise and a maximum ± 15% quantitative accuracy for the smallest lesion. The overall acquisition time was reduced by 23-42% using the proposed shorter variable than the current fixed-acquisition time for imaging legs, indicating that this is a useful and practical protocol for routine qualitative and quantitative PET/CT assessment in the clinical setting.

Monte-Carlo Simulation for Accuracy Assessment of a Single Camera Navigation System

NASA Astrophysics Data System (ADS)

Bethmann, F.; Luhmann, T.

2012-07-01

The paper describes a simulation-based optimization of an optical tracking system that is used as a 6DOF navigation system for neurosurgery. Compared to classical system used in clinical navigation, the presented system has two unique properties: firstly, the system will be miniaturized and integrated into an operating microscope for neurosurgery; secondly, due to miniaturization a single camera approach has been designed. Single camera techniques for 6DOF measurements show a special sensitivity against weak geometric configurations between camera and object. In addition, the achievable accuracy potential depends significantly on the geometric properties of the tracked objects (locators). Besides quality and stability of the targets used on the locator, their geometric configuration is of major importance. In the following the development and investigation of a simulation program is presented which allows for the assessment and optimization of the system with respect to accuracy. Different system parameters can be altered as well as different scenarios indicating the operational use of the system. Measurement deviations are estimated based on the Monte-Carlo method. Practical measurements validate the correctness of the numerical simulation results.

Clinical application of in vivo treatment delivery verification based on PET/CT imaging of positron activity induced at high energy photon therapy

NASA Astrophysics Data System (ADS)

Janek Strååt, Sara; Andreassen, Björn; Jonsson, Cathrine; Noz, Marilyn E.; Maguire, Gerald Q., Jr.; Näfstadius, Peder; Näslund, Ingemar; Schoenahl, Frederic; Brahme, Anders

2013-08-01

The purpose of this study was to investigate in vivo verification of radiation treatment with high energy photon beams using PET/CT to image the induced positron activity. The measurements of the positron activation induced in a preoperative rectal cancer patient and a prostate cancer patient following 50 MV photon treatments are presented. A total dose of 5 and 8 Gy, respectively, were delivered to the tumors. Imaging was performed with a 64-slice PET/CT scanner for 30 min, starting 7 min after the end of the treatment. The CT volume from the PET/CT and the treatment planning CT were coregistered by matching anatomical reference points in the patient. The treatment delivery was imaged in vivo based on the distribution of the induced positron emitters produced by photonuclear reactions in tissue mapped on to the associated dose distribution of the treatment plan. The results showed that spatial distribution of induced activity in both patients agreed well with the delivered beam portals of the treatment plans in the entrance subcutaneous fat regions but less so in blood and oxygen rich soft tissues. For the preoperative rectal cancer patient however, a 2 ± (0.5) cm misalignment was observed in the cranial-caudal direction of the patient between the induced activity distribution and treatment plan, indicating a beam patient setup error. No misalignment of this kind was seen in the prostate cancer patient. However, due to a fast patient setup error in the PET/CT scanner a slight mis-position of the patient in the PET/CT was observed in all three planes, resulting in a deformed activity distribution compared to the treatment plan. The present study indicates that the induced positron emitters by high energy photon beams can be measured quite accurately using PET imaging of subcutaneous fat to allow portal verification of the delivered treatment beams. Measurement of the induced activity in the patient 7 min after receiving 5 Gy involved count rates which were about 20 times lower than that of a patient undergoing standard 18F-FDG treatment. When using a combination of short lived nuclides such as 15O (half-life: 2 min) and 11C (half-life: 20 min) with low activity it is not optimal to use clinical reconstruction protocols. Thus, it might be desirable to further optimize reconstruction parameters as well as to address hardware improvements in realizing in vivo treatment verification with PET/CT in the future. A significant improvement with regard to 15O imaging could also be expected by having the PET/CT unit located close to the radiation treatment room.

Flutriciclamide (18F-GE180) PET: First-in-Human PET Study of Novel Third-Generation In Vivo Marker of Human Translocator Protein.

PubMed

Fan, Zhen; Calsolaro, Valeria; Atkinson, Rebecca A; Femminella, Grazia D; Waldman, Adam; Buckley, Christopher; Trigg, William; Brooks, David J; Hinz, Rainer; Edison, Paul

2016-11-01

Neuroinflammation is associated with neurodegenerative disease. PET radioligands targeting the 18-kDa translocator protein (TSPO) have been used as in vivo markers of neuroinflammation, but there is an urgent need for novel probes with improved signal-to-noise ratio. Flutriciclamide ( 18 F-GE180) is a recently developed third-generation TSPO ligand. In this first study, we evaluated the optimum scan duration and kinetic modeling strategies for 18 F-GE180 PET in (older) healthy controls. Ten healthy controls, 6 TSPO high-affinity binders, and 4 mixed-affinity binders were recruited. All subjects underwent detailed neuropsychologic tests, MRI, and a 210-min 18 F-GE180 dynamic PET/CT scan using metabolite-corrected arterial plasma input function. We evaluated 5 different kinetic models: irreversible and reversible 2-tissue-compartment models, a reversible 1-tissue model, and 2 models with an extra irreversible vascular compartment. The minimal scan duration was established using 210-min scan data. The feasibility of generating parametric maps was also investigated using graphical analysis. 18 F-GE180 concentration was higher in plasma than in whole blood during the entire scan duration. The volume of distribution (V T ) was 0.17 in high-affinity binders and 0.12 in mixed-affinity binders using the kinetic model. The model that best represented brain 18 F-GE180 kinetics across regions was the reversible 2-tissue-compartment model (2TCM4k), and 90 min resulted as the optimum scan length required to obtain stable estimates. Logan graphical analysis with arterial input function gave a V T highly consistent with V T in the kinetic model, which could be used for voxelwise analysis. We report for the first time, to our knowledge, the kinetic properties of the novel third-generation TSPO PET ligand 18 F-GE180 in humans: 2TCM4k is the optimal method to quantify the brain uptake, 90 min is the optimal scan length, and the Logan approach could be used to generate parametric maps. Although these control subjects have shown relatively low V T , the methodology presented here forms the basis for quantification for future PET studies using 18 F-GE180 in different pathologies. © 2016 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

Experimental task-based optimization of a four-camera variable-pinhole small-animal SPECT system

NASA Astrophysics Data System (ADS)

Hesterman, Jacob Y.; Kupinski, Matthew A.; Furenlid, Lars R.; Wilson, Donald W.

2005-04-01

We have previously utilized lumpy object models and simulated imaging systems in conjunction with the ideal observer to compute figures of merit for hardware optimization. In this paper, we describe the development of methods and phantoms necessary to validate or experimentally carry out these optimizations. Our study was conducted on a four-camera small-animal SPECT system that employs interchangeable pinhole plates to operate under a variety of pinhole configurations and magnifications (representing optimizable system parameters). We developed a small-animal phantom capable of producing random backgrounds for each image sequence. The task chosen for the study was the detection of a 2mm diameter sphere within the phantom-generated random background. A total of 138 projection images were used, half of which included the signal. As our observer, we employed the channelized Hotelling observer (CHO) with Laguerre-Gauss channels. The signal-to-noise (SNR) of this observer was used to compare different system configurations. Results indicate agreement between experimental and simulated data with higher detectability rates found for multiple-camera, multiple-pinhole, and high-magnification systems, although it was found that mixtures of magnifications often outperform systems employing a single magnification. This work will serve as a basis for future studies pertaining to system hardware optimization.

Nuclear Cardiology: Are We Using the Right Protocols and Tracers the Right Way?

PubMed

Dondi, Maurizio; Pascual, Thomas; Paez, Diana; Einstein, Andrew J

2017-12-01

The field of nuclear cardiology has changed considerably over recent years, with greater attention paid to safety and radiation protection issues. The wider usage of technetium-99m (Tc-99m)-labeled radiopharmaceuticals for single-photon emission computed tomography (SPECT) imaging using gamma cameras has contributed to better quality studies and lower radiation exposure to patients. Increased availability of tracers and scanners for positron emission tomography (PET) will help further improve the quality of studies and quantify myocardial blood flow and myocardial flow reserve, thus enhancing the contribution of non-invasive imaging to the management of coronary artery disease. The introduction of new instrumentation such as solid state cameras and new software will help reduce further radiation exposure to patients undergoing nuclear cardiology studies. Results from recent studies, focused on assessing the relationship between best practices and radiation risk, provide useful insights on simple measures to improve the safety of nuclear cardiology studies without compromising the quality of results.

4D laser camera for accurate patient positioning, collision avoidance, image fusion and adaptive approaches during diagnostic and therapeutic procedures.

PubMed

Brahme, Anders; Nyman, Peter; Skatt, Björn

2008-05-01

A four-dimensional (4D) laser camera (LC) has been developed for accurate patient imaging in diagnostic and therapeutic radiology. A complementary metal-oxide semiconductor camera images the intersection of a scanned fan shaped laser beam with the surface of the patient and allows real time recording of movements in a three-dimensional (3D) or four-dimensional (4D) format (3D +time). The LC system was first designed as an accurate patient setup tool during diagnostic and therapeutic applications but was found to be of much wider applicability as a general 4D photon "tag" for the surface of the patient in different clinical procedures. It is presently used as a 3D or 4D optical benchmark or tag for accurate delineation of the patient surface as demonstrated for patient auto setup, breathing and heart motion detection. Furthermore, its future potential applications in gating, adaptive therapy, 3D or 4D image fusion between most imaging modalities and image processing are discussed. It is shown that the LC system has a geometrical resolution of about 0, 1 mm and that the rigid body repositioning accuracy is about 0, 5 mm below 20 mm displacements, 1 mm below 40 mm and better than 2 mm at 70 mm. This indicates a slight need for repeated repositioning when the initial error is larger than about 50 mm. The positioning accuracy with standard patient setup procedures for prostate cancer at Karolinska was found to be about 5-6 mm when independently measured using the LC system. The system was found valuable for positron emission tomography-computed tomography (PET-CT) in vivo tumor and dose delivery imaging where it potentially may allow effective correction for breathing artifacts in 4D PET-CT and image fusion with lymph node atlases for accurate target volume definition in oncology. With a LC system in all imaging and radiation therapy rooms, auto setup during repeated diagnostic and therapeutic procedures may save around 5 min per session, increase accuracy and allow efficient image fusion between all imaging modalities employed.

A rib-specific multimodal registration algorithm for fused unfolded rib visualization using PET/CT

NASA Astrophysics Data System (ADS)

Kaftan, Jens N.; Kopaczka, Marcin; Wimmer, Andreas; Platsch, Günther; Declerck, Jérôme

2014-03-01

Respiratory motion affects the alignment of PET and CT volumes from PET/CT examinations in a non-rigid manner. This becomes particularly apparent if reviewing fine anatomical structures such as ribs when assessing bone metastases, which frequently occur in many advanced cancers. To make this routine diagnostic task more efficient, a fused unfolded rib visualization for 18F-NaF PET/CT is presented. It allows to review the whole rib cage in a single image. This advanced visualization is enabled by a novel rib-specific registration algorithm that rigidly optimizes the local alignment of each individual rib in both modalities based on a matched filter response function. More specifically, rib centerlines are automatically extracted from CT and subsequently individually aligned to the corresponding bone-specific PET rib uptake pattern. The proposed method has been validated on 20 PET/CT scans acquired at different clinical sites. It has been demonstrated that the presented rib- specific registration method significantly improves the rib alignment without having to run complex deformable registration algorithms. At the same time, it guarantees that rib lesions are not further deformed, which may otherwise affect quantitative measurements such as SUVs. Considering clinically relevant distance thresholds, the centerline portion with good alignment compared to the ground truth improved from 60:6% to 86:7% after registration while approximately 98% can be still considered as acceptably aligned.

Concurrent PET/CT with an integrated imaging system: intersociety dialogue from the joint working group of the American College of Radiology, the Society of Nuclear Medicine, and the Society of Computed Body Tomography and Magnetic Resonance.

PubMed

Coleman, R Edward; Delbeke, Dominique; Guiberteau, Milton J; Conti, Peter S; Royal, Henry D; Weinreb, Jeffrey C; Siegel, Barry A; Federle, Michael F; Townsend, David W; Berland, Lincoln L

2005-07-01

Rapid advances in imaging technology are a challenge for health care professionals, who must determine how best to use these technologies to optimize patient care and outcomes. Hybrid imaging instrumentation, combining 2 or more new or existing technologies, each with its own separate history of clinical evolution, such as PET and CT, may be especially challenging. CT and PET provide complementary anatomic information and molecular information, respectively, with PET giving specificity to anatomic findings and CT offering precise localization of metabolic activity. Historically, the acquisition and interpretation of the 2 image sets have been performed separately and very often at different times and locales. Recently, integrated PET/CT systems have become available; these systems provide PET and CT images that are acquired nearly simultaneously and are capable of producing superimposed, coregistered images, greatly facilitating interpretation. As the implementation of this integrated technology has become more widespread in the setting of oncologic imaging, questions and concerns regarding equipment specifications, image acquisition protocols, supervision, interpretation, professional qualifications, and safety have arisen. This article summarizes the discussions and observations surrounding these issues by a collaborative working group consisting of representatives from the American College of Radiology, the Society of Nuclear Medicine, and the Society of Computed Body Tomography and Magnetic Resonance.

Concurrent PET/CT with an integrated imaging system: intersociety dialogue from the Joint Working Group of the American College of Radiology, the Society of Nuclear Medicine, and the Society of Computed Body Tomography and Magnetic Resonance.

PubMed

Coleman, R Edward; Delbeke, Dominique; Guiberteau, Milton J; Conti, Peter S; Royal, Henry D; Weinreb, Jeffrey C; Siegel, Barry A; Federle, Michael P; Townsend, David W; Berland, Lincoln L

2005-07-01

Rapid advances in imaging technology are a challenge for health care professionals, who must determine how best to use these technologies to optimize patient care and outcomes. Hybrid imaging instrumentation, combining 2 or more new or existing technologies, each with its own separate history of clinical evolution, such as PET and CT, may be especially challenging. CT and PET provide complementary anatomic information and molecular information, respectively, with PET giving specificity to anatomic findings and CT offering precise localization of metabolic activity. Historically, the acquisition and interpretation of the 2 image sets have been performed separately and very often at different times and locales. Recently, integrated PET/CT systems have become available; these systems provide PET and CT images that are acquired nearly simultaneously and are capable of producing superimposed, coregistered images, greatly facilitating interpretation. As the implementation of this integrated technology has become more widespread in the setting of oncologic imaging, questions and concerns regarding equipment specifications, image acquisition protocols, supervision, interpretation, professional qualifications, and safety have arisen. This article summarizes the discussions and observations surrounding these issues by a collaborative working group consisting of representatives from the American College of Radiology, the Society of Nuclear Medicine, and the Society of Computed Body Tomography and Magnetic Resonance.

Influence of detector pixel size, TOF resolution and DOI on image quality in MR-compatible whole-body PET.

PubMed

Thoen, Hendrik; Keereman, Vincent; Mollet, Pieter; Van Holen, Roel; Vandenberghe, Stefaan

2013-09-21

The optimization of a whole-body PET system remains a challenging task, as the imaging performance is influenced by a complex interaction of different design parameters. However, it is not always clear which parameters have the largest impact on image quality and are most eligible for optimization. To determine this, we need to be able to assess their influence on image quality. We performed Monte-Carlo simulations of a whole-body PET scanner to predict the influence on image quality of three detector parameters: the TOF resolution, the transverse pixel size and depth-of-interaction (DOI)-correction. The inner diameter of the PET scanner was 65 cm, small enough to allow physical integration into a simultaneous PET-MR system. Point sources were used to evaluate the influence of transverse pixel size and DOI-correction on spatial resolution as function of radial distance. To evaluate the influence on contrast recovery and pixel noise a cylindrical phantom of 35 cm diameter was used, representing a large patient. The phantom contained multiple hot lesions with 5 mm diameter. These lesions were placed at radial distances of 50, 100 and 150 mm from the center of the field-of-view, to be able to study the effects at different radial positions. The non-prewhitening (NPW) observer was used for objective analysis of the detectability of the hot lesions in the cylindrical phantom. Based on this analysis the NPW-SNR was used to quantify the relative improvements in image quality due to changes of the variable detector parameters. The image quality of a whole-body PET scanner can be improved significantly by reducing the transverse pixel size from 4 to 2.6 mm and improving the TOF resolution from 600 to 400 ps and further from 400 to 200 ps. Compared to pixel size, the TOF resolution has the larger potential to increase image quality for the simulated phantom. The introduction of two layer DOI-correction only leads to a modest improvement for the spheres at radial distance of 150 mm from the center of the transaxial FOV.

The MINDView brain PET detector, feasibility study based on SiPM arrays

NASA Astrophysics Data System (ADS)

González, Antonio J.; Majewski, Stan; Sánchez, Filomeno; Aussenhofer, Sebastian; Aguilar, Albert; Conde, Pablo; Hernández, Liczandro; Vidal, Luis F.; Pani, Roberto; Bettiol, Marco; Fabbri, Andrea; Bert, Julien; Visvikis, Dimitris; Jackson, Carl; Murphy, John; O'Neill, Kevin; Benlloch, Jose M.

2016-05-01

The Multimodal Imaging of Neurological Disorders (MINDView) project aims to develop a dedicated brain Positron Emission Tomography (PET) scanner with sufficient resolution and sensitivity to visualize neurotransmitter pathways and their disruptions in mental disorders for diagnosis and follow-up treatment. The PET system should be compact and fully compatible with a Magnetic Resonance Imaging (MRI) device in order to allow its operation as a PET brain insert in a hybrid imaging setup with most MRI scanners. The proposed design will enable the currently-installed MRI base to be easily upgraded to PET/MRI systems. The current design for the PET insert consists of a 3-ring configuration with 20 modules per ring and an axial field of view of ~15 cm and a geometrical aperture of ~33 cm in diameter. When coupled to the new head Radio Frequency (RF) coil, the inner usable diameter of the complete PET-RF coil insert is reduced to 26 cm. Two scintillator configurations have been tested, namely a 3-layer staggered array of LYSO with 1.5 mm pixel size, with 35×35 elements (6 mm thickness each) and a black-painted monolithic LYSO block also covering about 50×50 mm2 active area with 20 mm thickness. Laboratory test results associated with the current MINDView PET module concept are presented in terms of key parameters' optimization, such as spatial and energy resolution, sensitivity and Depth of Interaction (DOI) capability. It was possible to resolve all pixel elements from the three scintillator layers with energy resolutions as good as 10%. The monolithic scintillator showed average detector resolutions varying from 3.5 mm in the entrance layer to better than 1.5 mm near the photosensor, with average energy resolutions of about 17%.

Vertebral metastases from neuroendocrine tumours: How to avoid false positives on 68Ga-DOTA-TOC PET using CT pattern analysis?

PubMed

Gauthé, Mathieu; Testart Dardel, Nathalie; Ruiz Santiago, Fernando; Ohnona, Jessica; Nataf, Valérie; Montravers, Françoise; Talbot, Jean-Noël

2018-03-12

To develop criteria to improve discrimination between vertebral metastases from neuroendocrine tumours (NETs) and benign bone lesions on PET combined with CT using DOTA-D-Phe 1 -Tyr 3 -octreotide labelled with gallium-68 ( 68 Ga-DOTA-TOC). In 535 NET patients, 68 Ga-DOTA-TOC PET/CT examinations were reviewed retrospectively for vertebral CT lesions and/or PET foci. For each vertebral PET abnormality, appearance on CT, biological volume (BV), standardized uptake value (SUV max ) and ratios to those of reference organs were determined. All vertebral abnormalities were characterized as a metastasis, a typical vertebral haemangioma (VH) or other benign lesion. In 79 patients (14.8 %), we found 107 metastases, 34 VHs and 31 other benign lesions in the spine. The optimal cut-off values to differentiate metastases from benign lesions were BV ≥0.72 cm 3 , SUVmax ≥2, SUVmax ratio to a reference vertebra ≥2.1, to liver ≥0.28 and to spleen ≥0.14. They corresponded to lesion-based 68 Ga-DOTA-TOC PET/CT sensitivity of 87 %, 98 %, 97 %, 99 % and 94 %, and specificity of 55 %, 100 %, 90 %, 97 %, 100 %, respectively. The high sensitivity of 68 Ga-DOTA-TOC-PET/CT in detecting NET vertebral metastases was confirmed; this study showed that specificity could be improved by combining CT features and quantifying 68 Ga-DOTA-TOC uptake. • Bone metastases in neuroendocrine tumours correlate with prognosis. • Benign bone lesions may mimic metastases on 68 Ga-DOTA-TOC PET/CT imaging. • The specific polka-dot CT pattern may be missing in some vertebral haemangiomas. • Lesion atypical for haemangiomas can be better characterized by quantifying 68 Ga-DOTA-TOC uptake.

Determination of oligomers in virgin and recycled polyethylene terephthalate (PET) samples by UPLC-MS-QTOF.

PubMed

Ubeda, Sara; Aznar, Margarita; Nerín, Cristina

2018-03-01

An oligomer is a molecule that consists of a few monomer units. It can be formed during polymer manufacturing and also due to polymer degradation processes or even during use conditions. Since oligomers are not included in chemical databases, their identification is a complex process. In this work, the oligomers present in 20 different PET pellet samples have been determined. Two different sample treatment procedures, solvent extraction and total dissolution, were applied in order to select the most efficient one. The analyses were carried out by UPLC-MS-QTOF. The use of high resolution mass spectrometry allowed the structural elucidation of these compounds and their correct identification. The main oligomers identified were cyclic as well as lineal from the first, second, and third series. All of them were composed of terephthalic acid (TPA), diethylene glycol (DEG), and ethylene glycol (EG). Quantitative values were very different in both procedures. In total dissolution of PET samples, the concentration of oligomers was always, at least, 10 times higher than in solvent extraction; some of the compounds were only detected when total dissolution was used. Results showed that the oligomers with the highest concentration values were dimers and trimers, cyclic, as well as lineal, from the first and second series. The oligomer with the maximum concentration value was TPA 2 -EG-DEG that was found in all the samples in a concentration range from 2493 to 19,290 ng/g PET. No differences between virgin and recycled PET were found. Migration experiments were performed in two PET bottles, and results showed the transference of most of these oligomers to a fat food simulant (ethanol 95%). Graphical abstract Graphical abstract of the two procedures developd and optimized for identifying oligomers in PET pellets and in migration form PET bottles.

A Gain-Programmable Transit-Time-Stable and Temperature-Stable PMT Voltage Divider

NASA Astrophysics Data System (ADS)

Liu, Yaqiang; Li, Hongdi; Wang, Yu; Xing, Tao; Xie, Shuping; Uribe, J.; Baghaei, H.; Ramirez, R.; Kim, Soonseok; Wong, Wai-Hoi

2004-10-01

A gain-programmable, transit-time-stable, temperature-stable photomultiplier (PMT) voltage divider design is described in this paper. The signal-to-noise ratio can be increased by changing a PMT gain directly instead of adjusting the gain of the preamplifier. PMT gain can be changed only by adjusting the voltages for the dynodes instead of changing the total high voltage between the anode and the photocathode, which can cause a significant signal transit-time variation that cannot be accepted by an application with a critical timing requirement, such as positron emission tomography (PET) or time-of-flight (TOF) detection/PET. The dynode voltage can be controlled by a digital analog converter isolated with a linear optocoupler. The optocoupler consists of an infrared light emission diode (LED) optically coupled with two phototransistors, and one is used in a servo feedback circuit to control the LED drive current for compensating temperature characteristics. The results showed that a six times gain range could be achieved; the gain drift was <0.5% over a 20/spl deg/C temperature range; 250 ps transit-time variation was measured over the entire gain range. A compact print circuit board (PCB) for the voltage divider integrated with a fixed-gain preamplifier has been designed and constructed. It can save about $30 per PMT channel compared with a commercial PMT voltage divider along with a variable gain amplifier. The preamplifier can be totally disabled, therefore in a system with a large amount of PMTs, only one channel can be enabled for calibrating the PMT gain. This new PMT voltage divider design is being applied to our animal PET camera and TOF/PET research.

SU-E-J-254: Evaluating the Role of Mid-Treatment and Post-Treatment FDG-PET/CT in Predicting Progression-Free Survival and Distant Metastasis of Anal Cancer Patients Treated with Chemoradiotherapy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, H; Wang, J; Chuong, M

2015-06-15

Purpose: To evaluate the role of mid-treatment and post-treatment FDG-PET/CT in predicting progression-free survival (PFS) and distant metastasis (DM) of anal cancer patients treated with chemoradiotherapy (CRT). Methods: 17 anal cancer patients treated with CRT were retrospectively studied. The median prescription dose was 56 Gy (range, 50–62.5 Gy). All patients underwent FDG-PET/CT scans before and after CRT. 16 of the 17 patients had an additional FDG-PET/CT image at 3–5 weeks into the treatment (denoted as mid-treatment FDG-PET/CT). 750 features were extracted from these three sets of scans, which included both traditional PET/CT measures (SUVmax, SUVpeak, tumor diameters, etc.) and spatialtemporalmore » PET/CT features (comprehensively quantify a tumor’s FDG uptake intensity and distribution, spatial variation (texture), geometric property and their temporal changes relative to baseline). 26 clinical parameters (age, gender, TNM stage, histology, GTV dose, etc.) were also analyzed. Advanced analytics including methods to select an optimal set of predictors and a model selection engine, which identifies the most accurate machine learning algorithm for predictive analysis was developed. Results: Comparing baseline + mid-treatment PET/CT set to baseline + posttreatment PET/CT set, 14 predictors were selected from each feature group. Same three clinical parameters (tumor size, T stage and whether 5-FU was held during any cycle of chemotherapy) and two traditional measures (pre- CRT SUVmin and SUVmedian) were selected by both predictor groups. Different mix of spatial-temporal PET/CT features was selected. Using the 14 predictors and Naive Bayes, mid-treatment PET/CT set achieved 87.5% accuracy (2 PFS patients misclassified, all local recurrence and DM patients correctly classified). Post-treatment PET/CT set achieved 94.0% accuracy (all PFS and DM patients correctly predicted, 1 local recurrence patient misclassified) with logistic regression, neural network or support vector machine model. Conclusion: Applying radiomics approach to either midtreatment or post-treatment PET/CT could achieve high accuracy in predicting anal cancer treatment outcomes. This work was supported in part by the National Cancer Institute Grant R01CA172638.« less

Large-Scale High-Resolution Cylinder Wake Measurements in a Wind Tunnel using Tomographic PIV with sCMOS Cameras

NASA Astrophysics Data System (ADS)

Michaelis, Dirk; Schroeder, Andreas

2012-11-01

Tomographic PIV has triggered vivid activity, reflected in a large number of publications, covering both: development of the technique and a wide range of fluid dynamic experiments. Maturing of tomo PIV allows the application in medium to large scale wind tunnels. Limiting factor for wind tunnel application is the small size of the measurement volume, being typically about of 50 × 50 × 15 mm3. Aim of this study is the optimization towards large measurement volumes and high spatial resolution performing cylinder wake measurements in a 1 meter wind tunnel. Main limiting factors for the volume size are the laser power and the camera sensitivity. So, a high power laser with 800 mJ per pulse is used together with low noise sCMOS cameras, mounted in forward scattering direction to gain intensity due to the Mie scattering characteristics. A mirror is used to bounce the light back, to have all cameras in forward scattering. Achievable particle density is growing with number of cameras, so eight cameras are used for a high spatial resolution. Optimizations lead to volume size of 230 × 200 × 52 mm3 = 2392 cm3, more than 60 times larger than previously. 281 × 323 × 68 vectors are calculated with spacing of 0.76 mm. The achieved measurement volume size and spatial resolution is regarded as a major step forward in the application of tomo PIV in wind tunnels. Supported by EU-project: no. 265695.

Concentration solar power optimization system and method of using the same

DOEpatents

Andraka, Charles E

2014-03-18

A system and method for optimizing at least one mirror of at least one CSP system is provided. The system has a screen for displaying light patterns for reflection by the mirror, a camera for receiving a reflection of the light patterns from the mirror, and a solar characterization tool. The solar characterization tool has a characterizing unit for determining at least one mirror parameter of the mirror based on an initial position of the camera and the screen, and a refinement unit for refining the determined parameter(s) based on an adjusted position of the camera and screen whereby the mirror is characterized. The system may also be provided with a solar alignment tool for comparing at least one mirror parameter of the mirror to a design geometry whereby an alignment error is defined, and at least one alignment unit for adjusting the mirror to reduce the alignment error.

Signal intensity analysis and optimization for in vivo imaging of Cherenkov and excited luminescence

NASA Astrophysics Data System (ADS)

LaRochelle, Ethan P. M.; Shell, Jennifer R.; Gunn, Jason R.; Davis, Scott C.; Pogue, Brian W.

2018-04-01

During external beam radiotherapy (EBRT), in vivo Cherenkov optical emissions can be used as a dosimetry tool or to excite luminescence, termed Cherenkov-excited luminescence (CEL) with microsecond-level time-gated cameras. The goal of this work was to develop a complete theoretical foundation for the detectable signal strength, in order to provide guidance on optimization of the limits of detection and how to optimize near real time imaging. The key parameters affecting photon production, propagation and detection were considered and experimental validation with both tissue phantoms and a murine model are shown. Both the theoretical analysis and experimental data indicate that the detection level is near a single photon-per-pixel for the detection geometry and frame rates commonly used, with the strongest factor being the signal decrease with the square of distance from tissue to camera. Experimental data demonstrates how the SNR improves with increasing integration time, but only up to the point where the dominance of camera read noise is overcome by stray photon noise that cannot be suppressed. For the current camera in a fixed geometry, the signal to background ratio limits the detection of light signals, and the observed in vivo Cherenkov emission is on the order of 100×  stronger than CEL signals. As a result, imaging signals from depths  <15 mm is reasonable for Cherenkov light, and depths  <3 mm is reasonable for CEL imaging. The current investigation modeled Cherenkov and CEL imaging of two oxygen sensing phosphorescent compounds, but the modularity of the code allows for easy comparison of different agents or alternative cameras, geometries or tissues.

Signal intensity analysis and optimization for in vivo imaging of Cherenkov and excited luminescence.

PubMed

LaRochelle, Ethan P M; Shell, Jennifer R; Gunn, Jason R; Davis, Scott C; Pogue, Brian W

2018-04-20

During external beam radiotherapy (EBRT), in vivo Cherenkov optical emissions can be used as a dosimetry tool or to excite luminescence, termed Cherenkov-excited luminescence (CEL) with microsecond-level time-gated cameras. The goal of this work was to develop a complete theoretical foundation for the detectable signal strength, in order to provide guidance on optimization of the limits of detection and how to optimize near real time imaging. The key parameters affecting photon production, propagation and detection were considered and experimental validation with both tissue phantoms and a murine model are shown. Both the theoretical analysis and experimental data indicate that the detection level is near a single photon-per-pixel for the detection geometry and frame rates commonly used, with the strongest factor being the signal decrease with the square of distance from tissue to camera. Experimental data demonstrates how the SNR improves with increasing integration time, but only up to the point where the dominance of camera read noise is overcome by stray photon noise that cannot be suppressed. For the current camera in a fixed geometry, the signal to background ratio limits the detection of light signals, and the observed in vivo Cherenkov emission is on the order of 100×  stronger than CEL signals. As a result, imaging signals from depths  <15 mm is reasonable for Cherenkov light, and depths  <3 mm is reasonable for CEL imaging. The current investigation modeled Cherenkov and CEL imaging of two oxygen sensing phosphorescent compounds, but the modularity of the code allows for easy comparison of different agents or alternative cameras, geometries or tissues.

An interior-point method for total variation regularized positron emission tomography image reconstruction

NASA Astrophysics Data System (ADS)

Bai, Bing

2012-03-01

There has been a lot of work on total variation (TV) regularized tomographic image reconstruction recently. Many of them use gradient-based optimization algorithms with a differentiable approximation of the TV functional. In this paper we apply TV regularization in Positron Emission Tomography (PET) image reconstruction. We reconstruct the PET image in a Bayesian framework, using Poisson noise model and TV prior functional. The original optimization problem is transformed to an equivalent problem with inequality constraints by adding auxiliary variables. Then we use an interior point method with logarithmic barrier functions to solve the constrained optimization problem. In this method, a series of points approaching the solution from inside the feasible region are found by solving a sequence of subproblems characterized by an increasing positive parameter. We use preconditioned conjugate gradient (PCG) algorithm to solve the subproblems directly. The nonnegativity constraint is enforced by bend line search. The exact expression of the TV functional is used in our calculations. Simulation results show that the algorithm converges fast and the convergence is insensitive to the values of the regularization and reconstruction parameters.

How long is enough to detect terrestrial animals? Estimating the minimum trapping effort on camera traps

PubMed Central

Si, Xingfeng; Kays, Roland

2014-01-01

Camera traps is an important wildlife inventory tool for estimating species diversity at a site. Knowing what minimum trapping effort is needed to detect target species is also important to designing efficient studies, considering both the number of camera locations, and survey length. Here, we take advantage of a two-year camera trapping dataset from a small (24-ha) study plot in Gutianshan National Nature Reserve, eastern China to estimate the minimum trapping effort actually needed to sample the wildlife community. We also evaluated the relative value of adding new camera sites or running cameras for a longer period at one site. The full dataset includes 1727 independent photographs captured during 13,824 camera days, documenting 10 resident terrestrial species of birds and mammals. Our rarefaction analysis shows that a minimum of 931 camera days would be needed to detect the resident species sufficiently in the plot, and c. 8700 camera days to detect all 10 resident species. In terms of detecting a diversity of species, the optimal sampling period for one camera site was c. 40, or long enough to record about 20 independent photographs. Our analysis of evaluating the increasing number of additional camera sites shows that rotating cameras to new sites would be more efficient for measuring species richness than leaving cameras at fewer sites for a longer period. PMID:24868493

Evaluation of the tourism climate in the Hexi Corridor of northwest China's Gansu Province during 1980-2012

NASA Astrophysics Data System (ADS)

Zhang, Fuxian; Zhang, Mingjun; Wang, Shengjie; Qiang, Fang; Che, Yanjun; Wang, Jie

2017-08-01

As a pivotal section of the Silk Road in northwest China, the Hexi Corridor is a popular tourist destination. In this study, the tourism climate conditions in this region were discussed using the Physiologically Equivalent Temperature (PET) and the Climate-Tourism/Transfer-information-Scheme (CTIS) from 1980 to 2012. Overall, cold or cool stress was prevalent in the area, and the optimal travel period was from May to September. With global warming, the annual numbers of cumulative days with relatively cold conditions decreased, and the annual numbers of cumulative days with comfortable and relatively hot conditions increased. Two typical stations, Wushaoling and Dunhuang, were compared and analysed for their tourism climate information according to the frequency of PET and CTIS conditions, respectively. In addition, regional variations in the tourism climate conditions based on geographic information systems (GIS) were investigated during the optimal travel period.

Highly flexible binder-free core-shell nanofibrous electrode for lightweight electrochemical energy storage using recycled water bottles

NASA Astrophysics Data System (ADS)

Shi, HaoTian H.; Naguib, Hani E.

2016-08-01

The creation of a novel flexible nanocomposite fiber with conductive polymer polyaniline (PAni) coating on a polyethylene terephthalate (PET) substrate allowed for increased electrochemical performance while retaining ideal mechanical properties such as very high flexibility. Binder-free PAni-wrapped PET (PAni@PET) fiber with a core-shell structure was successfully fabricated through a novel technique. The PET nanofiber substrate was fabricated through an optimized electrospinning method, while the PAni shell was chemically polymerized onto the surface of the nanofibers. The PET substrate can be made directly from recycled PETE1 grade plastic water bottles. The resulting nanofiber with an average diameter of 121 nm ± 39 nm, with a specific surface area of 83.72 m2 g-1, led to better ionic interactions at the electrode/electrolyte interface. The PAni active layer coating was found to be 69 nm in average thickness. The specific capacitance was found to have increased dramatically from pure PAni with carbon binders. The specific capacitance was found to be 347 F g-1 at a relatively high scan rate of 10 mV s-1. The PAni/PET fiber also experienced very little degradation (4.4%) in capacitance after 1500 galvanostatic charge/discharge cycles at a specific current of 1.2 A g-1. The mesoporous structure of the PAni@PET fibrous mat also allowed for tunable capacitance by controlling the pore sizes. This novel fabrication method offers insights for the utilization of recycled PETE1 based bottles as a high performance, low cost, highly flexible supercapacitor device.

Multimodal correlation of dynamic [18F]-AV-1451 perfusion PET and neuronal hypometabolism in [18F]-FDG PET.

PubMed

Hammes, Jochen; Leuwer, Isabel; Bischof, Gérard N; Drzezga, Alexander; van Eimeren, Thilo

2017-12-01

Cerebral glucose metabolism measured with [18F]-FDG PET is a well established marker of neuronal dysfunction in neurodegeneration. The tau-protein tracer [18F]-AV-1451 PET is currently under evaluation and shows promising results. Here, we assess the feasibility of early perfusion imaging with AV-1451 as a substite for FDG PET in assessing neuronal injury. Twenty patients with suspected neurodegeneration underwent FDG and early phase AV-1451 PET imaging. Ten one-minute timeframes were acquired after application of 200 MBq AV-1451. FDG images were acquired on a different date according to clinical protocol. Early AV-1451 timeframes were coregistered to individual FDG-scans and spatially normalized. Voxel-wise intermodal correlations were calculated on within-subject level for every possible time window. The window with highest pooled correlation was considered optimal. Z-transformed deviation maps (ZMs) were created from both FDG and early AV-1451 images, comparing against FDG images of healthy controls. Regional patterns and extent of perfusion deficits were highly comparable to metabolic deficits. Best results were observed in a time window from 60 to 360 s (r = 0.86). Correlation strength ranged from r = 0.96 (subcortical gray matter) to 0.83 (frontal lobe) in regional analysis. ZMs of early AV-1451 and FDG images were highly similar. Perfusion imaging with AV-1451 is a valid biomarker for assessment of neuronal dysfunction in neurodegenerative diseases. Radiation exposure and complexity of the diagnostic workup could be reduced significantly by routine acquisition of early AV-1451 images, sparing additional FDG PET.

PET Probe-Guided Surgery in Patients with Breast Cancer: Proposal for a Methodological Approach.

PubMed

Orsaria, Paolo; Chiaravalloti, Agostino; Fiorentini, Alessandro; Pistolese, Chiara; Vanni, Gianluca; Granai, Alessandra Vittoria; Varvaras, Dimitrios; Danieli, Roberta; Schillaci, Orazio; Petrella, Giuseppe; Buonomo, Oreste Claudio

2017-01-02

Although it is valuable for detecting distant metastases, identifying recurrence, and evaluating responses to chemotherapy, the role of 18 F-fluorodeoxyglucose positron-emission tomography/computed tomography ( 18 F-FDG PET/CT) in assessing locoregional nodal status for initial staging of breast cancer has not yet been well-defined in clinical practice. In the current report, we describe a new PET probe-based clinical approach, with evaluation of the technical performance of a handheld high-energy gamma probe for intraoperative localization of breast carcinomas, and evaluation of lymph node metastases during radio-guided oncological surgery. Three patients underwent a PET/CT scan immediately prior to surgery following the standard clinical protocol. Intraoperatively, tumors were localized and resected with the assistance of a hand-held gamma probe. PET-guided assessment of the presence or absence of regional nodal spread of malignancy was compared with the reference standard of histopathological examination. In all three cases, perioperative 18 F-FDG PET/CT imaging and intraoperative gamma probe detection verified complete resection of the hypermetabolic lesions and demonstrated no additional suspicious occult disease. This innovative approach demonstrates great promise for providing real-time access to metabolic and morphological tumor information that may lead to an optimal disease-tailored approach. In carefully selected indications, a PET probe can be a useful adjunct in surgical practice, but further trials with a larger number of patients need to be performed to verify these findings. Copyright© 2017, International Institute of Anticancer Research (Dr. George J. Delinasios), All rights reserved.

PSMA PET and radionuclide therapy in prostate cancer

PubMed Central

Bouchelouche, Kirsten; Turkbey, Baris; Choyke, Peter L.

2016-01-01

Prostate cancer (Pca) is the most common malignancy in men and a major cause of cancer death. Accurate imaging plays an important role in diagnosis, staging, restaging, detection of biochemical recurrence, and for therapy of PCa patients. Since no effective treatment is available for advanced PCa, there is an urgent need to develop new and more effective therapeutic strategies. In order to optimize treatment outcome, especially in high risk PCa patients, therapy of PCa is moving rapidly towards personalization. Medical imaging, including positron emission tomography (PET)/computed tomography (CT), plays an important role in personalized medicine in oncology. In the recent years, much focus has been on prostate specific membrane antigen (PSMA) as a promising target for imaging and therapy with radionuclides, since it is upregulated in most PCa. In the prostate, one potential role for PSMA PET imaging is to help guiding focal therapy. Several studies have shown great potential of PSMA PET/CT for initial staging, lymph node staging, and detection of recurrence of PCa, even at very low PSA values after primary therapy. Furthermore, studies have shown that PSMA PET/CT has a higher detection rate than choline PET/CT. Radiolabeled PSMA ligands for therapy show promise in several studies with metastatic PCa, and is an area of active investigation. The “Image and treat” strategy, with radiolabeled PSMA ligands, has the potential to improve the treatment outcome of PCa patients, and is paving the way for precision medicine in PCa. The aim of this review is to give an overview of recent advancement in PSMA PET and radionuclide therapy of PCa. PMID:27825432

Measurements from a Compact Cost-Effective Beamline for the THC14 PET Cyclotron

NASA Astrophysics Data System (ADS)

Dehnel, M. P.; Theroux, J.; Christensen, T.; Stewart, T. M.; Roeder, M.; Sirot, P.; Fasse, D.; Brasile, J. P.; Raoult, F.; Buckley, K.

2009-03-01

The THC14 PET Cyclotron produced by THALES specifies two compact cost-effective beamlines for high current PET radioisotope production. The design and development of the beamline system was reported previously in NIM B 261 (2007) pp 809-812. This paper describes the successful testing of this compact beamline at the first installation. A series of measurement data are presented starting from low current scintillator image data, higher current beam diagnostic data (baffles, collimators, targets) and finally a simultaneous dual beam run on Faraday Cups. The beamline system has proven to be a flexible and valuable tool for optimizing high current beam intensity distribution on target in a well-instrumented manner. This ability to tailor the beam characteristics for the target is particularly important as high power targets are developed which can handle very high beam currents.

Efficient large-scale graph data optimization for intelligent video surveillance

NASA Astrophysics Data System (ADS)

Shang, Quanhong; Zhang, Shujun; Wang, Yanbo; Sun, Chen; Wang, Zepeng; Zhang, Luming

2017-08-01

Society is rapidly accepting the use of a wide variety of cameras Location and applications: site traffic monitoring, parking Lot surveillance, car and smart space. These ones here the camera provides data every day in an analysis Effective way. Recent advances in sensor technology Manufacturing, communications and computing are stimulating.The development of new applications that can change the traditional Vision system incorporating universal smart camera network. This Analysis of visual cues in multi camera networks makes wide Applications ranging from smart home and office automation to large area surveillance and traffic surveillance. In addition, dense Camera networks, most of which have large overlapping areas of cameras. In the view of good research, we focus on sparse camera networks. One Sparse camera network using large area surveillance. As few cameras as possible, most cameras do not overlap Each other’s field of vision. This task is challenging Lack of knowledge of topology Network, the specific changes in appearance and movement Track different opinions of the target, as well as difficulties Understanding complex events in a network. In this review in this paper, we present a comprehensive survey of recent studies Results to solve the problem of topology learning, Object appearance modeling and global activity understanding sparse camera network. In addition, some of the current open Research issues are discussed.

Reconstruction of an input function from a dynamic PET water image using multiple tissue curves

NASA Astrophysics Data System (ADS)

Kudomi, Nobuyuki; Maeda, Yukito; Yamamoto, Yuka; Nishiyama, Yoshihiro

2016-08-01

Quantification of cerebral blood flow (CBF) is important for the understanding of normal and pathologic brain physiology. When CBF is assessed using PET with {{\\text{H}}2} 15O or C15O2, its calculation requires an arterial input function, which generally requires invasive arterial blood sampling. The aim of the present study was to develop a new technique to reconstruct an image derived input function (IDIF) from a dynamic {{\\text{H}}2} 15O PET image as a completely non-invasive approach. Our technique consisted of using a formula to express the input using tissue curve with rate constant parameter. For multiple tissue curves extracted from the dynamic image, the rate constants were estimated so as to minimize the sum of the differences of the reproduced inputs expressed by the extracted tissue curves. The estimated rates were used to express the inputs and the mean of the estimated inputs was used as an IDIF. The method was tested in human subjects (n  =  29) and was compared to the blood sampling method. Simulation studies were performed to examine the magnitude of potential biases in CBF and to optimize the number of multiple tissue curves used for the input reconstruction. In the PET study, the estimated IDIFs were well reproduced against the measured ones. The difference between the calculated CBF values obtained using the two methods was small as around  <8% and the calculated CBF values showed a tight correlation (r  =  0.97). The simulation showed that errors associated with the assumed parameters were  <10%, and that the optimal number of tissue curves to be used was around 500. Our results demonstrate that IDIF can be reconstructed directly from tissue curves obtained through {{\\text{H}}2} 15O PET imaging. This suggests the possibility of using a completely non-invasive technique to assess CBF in patho-physiological studies.

Longitudinal positron emission tomography imaging of glial cell activation in a mouse model of mesial temporal lobe epilepsy: Toward identification of optimal treatment windows.

PubMed

Nguyen, Duc-Loc; Wimberley, Catriona; Truillet, Charles; Jego, Benoit; Caillé, Fabien; Pottier, Géraldine; Boisgard, Raphaël; Buvat, Irène; Bouilleret, Viviane

2018-06-01

Mesiotemporal lobe epilepsy is the most common type of drug-resistant partial epilepsy, with a specific history that often begins with status epilepticus due to various neurological insults followed by a silent period. During this period, before the first seizure occurs, a specific lesion develops, described as unilateral hippocampal sclerosis (HS). It is still challenging to determine which drugs, administered at which time point, will be most effective during the formation of this epileptic process. Neuroinflammation plays an important role in pathophysiological mechanisms in epilepsy, and therefore brain inflammation biomarkers such as translocator protein 18 kDa (TSPO) can be potent epilepsy biomarkers. TSPO is associated with reactive astrocytes and microglia. A unilateral intrahippocampal kainate injection mouse model can reproduce the defining features of human temporal lobe epilepsy with unilateral HS and the pattern of chronic pharmacoresistant temporal seizures. We hypothesized that longitudinal imaging using TSPO positron emission tomography (PET) with 18 F-DPA-714 could identify optimal treatment windows in a mouse model during the formation of HS. The model was induced into the right dorsal hippocampus of male C57/Bl6 mice. Micro-PET/computed tomographic scanning was performed before model induction and along the development of the HS at 7 days, 14 days, 1 month, and 6 months. In vitro autoradiography and immunohistofluorescence were performed on additional mice at each time point. TSPO PET uptake reached peak at 7 days and mostly related to microglial activation, whereas after 14 days, reactive astrocytes were shown to be the main cells expressing TSPO, reflected by a continuing increased PET uptake. TSPO-targeted PET is a highly potent longitudinal biomarker of epilepsy and could be of interest to determine the therapeutic windows in epilepsy and to monitor response to treatment. Wiley Periodicals, Inc. © 2018 International League Against Epilepsy.

Stereo depth distortions in teleoperation

NASA Technical Reports Server (NTRS)

Diner, Daniel B.; Vonsydow, Marika

1988-01-01

In teleoperation, a typical application of stereo vision is to view a work space located short distances (1 to 3m) in front of the cameras. The work presented here treats converged camera placement and studies the effects of intercamera distance, camera-to-object viewing distance, and focal length of the camera lenses on both stereo depth resolution and stereo depth distortion. While viewing the fronto-parallel plane 1.4 m in front of the cameras, depth errors are measured on the order of 2cm. A geometric analysis was made of the distortion of the fronto-parallel plane of divergence for stereo TV viewing. The results of the analysis were then verified experimentally. The objective was to determine the optimal camera configuration which gave high stereo depth resolution while minimizing stereo depth distortion. It is found that for converged cameras at a fixed camera-to-object viewing distance, larger intercamera distances allow higher depth resolutions, but cause greater depth distortions. Thus with larger intercamera distances, operators will make greater depth errors (because of the greater distortions), but will be more certain that they are not errors (because of the higher resolution).

Thermo-mechanical simulation of liquid-supported stretch blow molding

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zimmer, J.; Stommel, M.

2015-05-22

Stretch blow molding is the well-established plastics forming method to produce Polyehtylene therephtalate (PET) bottles. An injection molded preform is heated up above the PET glass transition temperature (Tg∼85°C) and subsequently inflated by pressurized air into a closed cavity. In the follow-up filling process, the resulting bottle is filled with the final product. A recently developed modification of the process combines the blowing and filling stages by directly using the final liquid product to inflate the preform. In a previously published paper, a mechanical simulation and successful evaluation of this liquid-driven stretch blow molding process was presented. In this way,more » a realistic process parameter dependent simulation of the preform deformation throughout the forming process was enabled, whereas the preform temperature evolution during forming was neglected. However, the formability of the preform is highly reduced when the temperature sinks below Tg during forming. Experimental investigations show temperature-induced failure cases due to the fast heat transfer between hot preform and cold liquid. Therefore, in this paper, a process dependent simulation of the temperature evolution during processing to avoid preform failure is presented. For this purpose, the previously developed mechanical model is used to extract the time dependent thickness evolution. This information serves as input for the heat transfer simulation. The required material parameters are calibrated from preform cooling experiments recorded with an infrared-camera. Furthermore, the high deformation ratios during processing lead to strain induced crystallization. This exothermal reaction is included into the simulation by extracting data from preform measurements at different stages of deformation via Differential Scanning Calorimetry (DSC). Finally, the thermal simulation model is evaluated by free forming experiments, recorded by a high-speed infrared camera.« less

Ambient Dose Equivalent measured at the Instituto Nacional de Cancerologia Department of Nuclear Medicine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Avila, O.; Torres-Ulloa, C. L.; Facultad de Ciencias, Universidad Nacional Autonoma de Mexico, AP 70-542, 04510, DF

2010-12-07

Ambient dose equivalent values were determined in several sites at the Instituto Nacional de Cancerologia, Departmento de Medicina Nuclear, using TLD-100 and TLD-900 thermoluminescent dosemeters. Additionally, ambient dose equivalent was measured at a corridor outside the hospitalization room for patients treated with {sup 137}Cs brachytherapy. Dosemeter calibration was performed at the Instituto Nacional de Investigaciones Nucleares, Laboratorio de Metrologia, to known {sup 137}Cs gamma radiation air kerma. Radionuclides considered for this study are {sup 131}I, {sup 18}F, {sup 67}Ga, {sup 99m}Tc, {sup 111}In, {sup 201}Tl and {sup 137}Cs, with main gamma energies between 93 and 662 keV. Dosemeters were placedmore » during a five month period in the nuclear medicine rooms (containing gamma-cameras), injection corridor, patient waiting areas, PET/CT study room, hot lab, waste storage room and corridors next to the hospitalization rooms for patients treated with {sup 131}I and {sup 137}Cs. High dose values were found at the waste storage room, outside corridor of {sup 137}Cs brachytherapy patients and PET/CT area. Ambient dose equivalent rate obtained for the {sup 137}Cs brachytherapy corridor is equal to (18.51{+-}0.02)x10{sup -3} mSv/h. Sites with minimum doses are the gamma camera rooms, having ambient dose equivalent rates equal to (0.05{+-}0.03)x10{sup -3} mSv/h. Recommendations have been given to the Department authorities so that further actions are taken to reduce doses at high dose sites in order to comply with the ALARA principle (as low as reasonably achievable).« less

The added value of 68Ga-DOTA-TATE-PET to contrast-enhanced CT for primary site detection in CUP of neuroendocrine origin.

PubMed

Kazmierczak, Philipp M; Rominger, Axel; Wenter, Vera; Spitzweg, Christine; Auernhammer, Christoph; Angele, Martin K; Rist, Carsten; Cyran, Clemens C

2017-04-01

To quantify the additional value of 68 Ga-DOTA-TATE PET/CT in comparison with contrast-enhanced CT alone for primary tumour detection in neuroendocrine cancer of unknown primary (CUP-NET). In total, 38 consecutive patients (27 men, 11 women; mean age 62 years) with histologically proven CUP-NET who underwent a contrast-enhanced 68 Ga-DOTA-TATE PET/CT scan for primary tumour detection and staging between 2010 and 2014 were included in this IRB-approved retrospective study. Two blinded readers independently analysed the contrast-enhanced CT and 68 Ga-DOTA-TATE PET datasets separately and noted from which modality they suspected a primary tumour. Consensus was reached if the results were divergent. Postoperative histopathology (24 patients) and follow-up 68 Ga-DOTA-TATE PET/CT imaging (14 patients) served as the reference standards and statistical measures of diagnostic accuracy were calculated accordingly. The majority of confirmed primary tumours were located in the abdomen (ileum in 19 patients, pancreas in 12, lung in 2, small pelvis in 1). High interobserver agreement was noted regarding the suspected primary tumour site (Cohen's k 0.90, p < 0.001). 68 Ga-DOTA-TATE PET demonstrated a significantly higher sensitivity (94 % vs. 63 %, p = 0.005) and a significantly higher accuracy (87 % vs. 68 %, p = 0.003) than contrast-enhanced CT. Ga-DOTA-TATE PET/CT compared with contrast-enhanced CT alone provides an improvement in sensitivity of 50 % and an improvement in accuracy of 30 % in primary tumour detection in CUP-NET. • 68 Ga-DOTA-TATE PET augments the sensitivity of contrast-enhanced CT by 50 % • 68 Ga-DOTA-TATE PET augments the accuracy of contrast-enhanced CT by 30 % • Somatostatin receptor-targeted hybrid imaging optimizes primary tumour detection in CUP-NET.

Active Site Flexibility as a Hallmark for Efficient PET Degradation by I. sakaiensis PETase.

PubMed

Fecker, Tobias; Galaz-Davison, Pablo; Engelberger, Felipe; Narui, Yoshie; Sotomayor, Marcos; Parra, Loreto P; Ramírez-Sarmiento, César A

2018-03-27

Polyethylene terephthalate (PET) is one of the most-consumed synthetic polymers, with an annual production of 50 million tons. Unfortunately, PET accumulates as waste and is highly resistant to biodegradation. Recently, fungal and bacterial thermophilic hydrolases were found to catalyze PET hydrolysis with optimal activities at high temperatures. Strikingly, an enzyme from Ideonella sakaiensis, termed PETase, was described to efficiently degrade PET at room temperature, but the molecular basis of its activity is not currently understood. Here, a crystal structure of PETase was determined at 2.02 Å resolution and employed in molecular dynamics simulations showing that the active site of PETase has higher flexibility at room temperature than its thermophilic counterparts. This flexibility is controlled by a novel disulfide bond in its active site, with its removal leading to destabilization of the catalytic triad and reduction of the hydrolase activity. Molecular docking of a model substrate predicts that PET binds to PETase in a unique and energetically favorable conformation facilitated by several residue substitutions within its active site when compared to other enzymes. These computational predictions are in excellent agreement with recent mutagenesis and PET film degradation analyses. Finally, we rationalize the increased catalytic activity of PETase at room temperature through molecular dynamics simulations of enzyme-ligand complexes for PETase and other thermophilic PET-degrading enzymes at 298, 323, and 353 K. Our results reveal that both the binding pose and residue substitutions within PETase favor proximity between the catalytic residues and the labile carbonyl of the substrate at room temperature, suggesting a more favorable hydrolytic reaction. These results are valuable for enabling detailed evolutionary analysis of PET-degrading enzymes and for rational design endeavors aiming at increasing the efficiency of PETase and similar enzymes toward plastic degradation. Copyright © 2018 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Investigation of spatial resolution improvement by use of a mouth-insert detector in the helmet PET scanner.

PubMed

Ahmed, Abdella M; Tashima, Hideaki; Yamaya, Taiga

2018-03-01

The dominant factor limiting the intrinsic spatial resolution of a positron emission tomography (PET) system is the size of the crystal elements in the detector. To increase sensitivity and achieve high spatial resolution, it is essential to use advanced depth-of-interaction (DOI) detectors and arrange them close to the subject. The DOI detectors help maintain high spatial resolution by mitigating the parallax error caused by the thickness of the scintillator near the peripheral regions of the field-of-view. As an optimal geometry for a brain PET scanner, with high sensitivity and spatial resolution, we proposed and developed the helmet-chin PET scanner using 54 four-layered DOI detectors consisting of a 16 × 16 × 4 array of GSOZ scintillator crystals with dimensions of 2.8 × 2.8 × 7.5 mm 3 . All the detectors used in the helmet-chin PET scanner had the same spatial resolution. In this study, we conducted a feasibility study of a new add-on detector arrangement for the helmet PET scanner by replacing the chin detector with a segmented crystal cube, having high spatial resolution in all directions, which can be placed inside the mouth. The crystal cube (which we have named the mouth-insert detector) has an array of 20 × 20 × 20 LYSO crystal segments with dimensions of 1 × 1 × 1 mm 3 . Thus, the scanner is formed by the combination of the helmet and mouth-insert detectors, and is referred to as the helmet-mouth-insert PET scanner. The results show that the helmet-mouth-insert PET scanner has comparable sensitivity and improved spatial resolution near the center of the hemisphere, compared to the helmet-chin PET scanner.

Is there any significance of lung cancer histology to compare the diagnostic accuracies of (18)F-FDG-PET/CT and (99m)Tc-MDP BS for the detection of bone metastases in advanced NSCLC?

PubMed

Inal, Ali; Kaplan, Muhammed Ali; Kucukoner, Mehmet; Urakcı, Zuhat; Dostbil, Zeki; Komek, Hail; Onder, Hakan; Tasdemir, Bekir; Isıkdogan, Abdurrahman

2014-01-01

Bone scintigraphy (BS) and fluorine-18 deoxyglucose positron emission tomography computed tomography ((18)F-FDG-PET/CT) are widely used for the detection of bone involvement. The optimal imaging modality for the detection of bone metastases in histological subgroups of non-small cell lung cancer (NSCLC) remains ambiguous. The aim of this study was to compare the efficacy of (18)F-FDG-PET/C and 99mTc-methylene diphosphonate ((99m)Tc-MDP) BS in the detection of bone metastases of patients in NSCLC. Specifically, we compared the diagnostic accuracies of these imaging techniques evaluating bone metastasis in histological subgroups of NSCLC. Fifty-three patients with advanced NSCLC, who had undergone both (18)F-FDG-PET/CT and BS and were eventually diagnosed as having bone metastasis, were enrolled in this retrospective study. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of (18)F-FDG-PET/CT and BS were 90.4%, 99.4%, 98.1%, 96.6%, 97.0% and 84.6%, 93.1%, 82.5%, 93.2, 90.8%, respectively. The κ statistics were calculated for (18)F-FDG-PET/CT and BS. The κ-value was 0.67 between (18)F-FDG-PET/CT and BS in all patients. On the other hand, the κ-value was 0.65 in adenocarcinoma, and 0.61 in squamous cell carcinoma between (18)F-FDG-PET/CT and BS. The κ-values suggested excellent agreement between all patients and histological subgroups of NSCLC. (18)F-FDG-PET/CT was more favorable than BS in the screening of metastatic bone lesions, but the trend did not reach statistical significance in all patients and histological subgroups of NSCLC. Our results need to be validated in prospective and larger study clinical trials to further clarify this topic.

[18F]FEPPA a TSPO Radioligand: Optimized Radiosynthesis and Evaluation as a PET Radiotracer for Brain Inflammation in a Peripheral LPS-Injected Mouse Model.

PubMed

Vignal, Nicolas; Cisternino, Salvatore; Rizzo-Padoin, Nathalie; San, Carine; Hontonnou, Fortune; Gelé, Thibaut; Declèves, Xavier; Sarda-Mantel, Laure; Hosten, Benoît

2018-06-07

[ 18 F]FEPPA is a specific ligand for the translocator protein of 18 kDa (TSPO) used as a positron emission tomography (PET) biomarker for glial activation and neuroinflammation. [ 18 F]FEPPA radiosynthesis was optimized to assess in a mouse model the cerebral inflammation induced by an intraperitoneal injection of Salmonella enterica serovar Typhimurium lipopolysaccharides (LPS; 5 mg/kg) 24 h before PET imaging. [ 18 F]FEPPA was synthesized by nucleophilic substitution (90 °C, 10 min) with tosylated precursor, followed by improved semi-preparative HPLC purification (retention time 14 min). [ 18 F]FEPPA radiosynthesis were carried out in 55 min (from EOB). The non-decay corrected radiochemical yield were 34 ± 2% ( n = 17), and the radiochemical purity greater than 99%, with a molar activity of 198 ± 125 GBq/µmol at the end of synthesis. Western blot analysis demonstrated a 2.2-fold increase in TSPO brain expression in the LPS treated mice compared to controls. This was consistent with the significant increase of [ 18 F]FEPPA brain total volume of distribution ( V T ) estimated with pharmacokinetic modelling. In conclusion, [ 18 F]FEPPA radiosynthesis was implemented with high yields. The new purification/formulation with only class 3 solvents is more suitable for in vivo studies.

Calibration of a dual-PTZ camera system for stereo vision

NASA Astrophysics Data System (ADS)

Chang, Yau-Zen; Hou, Jung-Fu; Tsao, Yi Hsiang; Lee, Shih-Tseng

2010-08-01

In this paper, we propose a calibration process for the intrinsic and extrinsic parameters of dual-PTZ camera systems. The calibration is based on a complete definition of six coordinate systems fixed at the image planes, and the pan and tilt rotation axes of the cameras. Misalignments between estimated and ideal coordinates of image corners are formed into cost values to be solved by the Nelder-Mead simplex optimization method. Experimental results show that the system is able to obtain 3D coordinates of objects with a consistent accuracy of 1 mm when the distance between the dual-PTZ camera set and the objects are from 0.9 to 1.1 meters.

A comparative study between evaluation methods for quality control procedures for determining the accuracy of PET/CT registration

NASA Astrophysics Data System (ADS)

Cha, Min Kyoung; Ko, Hyun Soo; Jung, Woo Young; Ryu, Jae Kwang; Choe, Bo-Young

2015-08-01

The Accuracy of registration between positron emission tomography (PET) and computed tomography (CT) images is one of the important factors for reliable diagnosis in PET/CT examinations. Although quality control (QC) for checking alignment of PET and CT images should be performed periodically, the procedures have not been fully established. The aim of this study is to determine optimal quality control (QC) procedures that can be performed at the user level to ensure the accuracy of PET/CT registration. Two phantoms were used to carry out this study: the American college of Radiology (ACR)-approved PET phantom and National Electrical Manufacturers Association (NEMA) International Electrotechnical Commission (IEC) body phantom, containing fillable spheres. All PET/CT images were acquired on a Biograph TruePoint 40 PET/CT scanner using routine protocols. To measure registration error, the spatial coordinates of the estimated centers of the target slice (spheres) was calculated independently for the PET and the CT images in two ways. We compared the images from the ACR-approved PET phantom to that from the NEMA IEC body phantom. Also, we measured the total time required from phantom preparation to image analysis. The first analysis method showed a total difference of 0.636 ± 0.11 mm for the largest hot sphere and 0.198 ± 0.09 mm for the largest cold sphere in the case of the ACR-approved PET phantom. In the NEMA IEC body phantom, the total difference was 3.720 ± 0.97 mm for the largest hot sphere and 4.800 ± 0.85 mm for the largest cold sphere. The second analysis method showed that the differences in the x location at the line profile of the lesion on PET and CT were (1.33, 1.33) mm for a bone lesion, (-1.26, -1.33) mm for an air lesion and (-1.67, -1.60) mm for a hot sphere lesion for the ACR-approved PET phantom. For the NEMA IEC body phantom, the differences in the x location at the line profile of the lesion on PET and CT were (-1.33, 4.00) mm for the air lesion and (1.33, -1.29) mm for a hot sphere lesion. These registration errors from this study were reasonable compared to the errors reported in previous studies. Meanwhile, the total time required from phantom preparation was 67.72 ± 4.50 min for the ACR-approved PET phantom and 96.78 ± 8.50 min for the NEMA IEC body phantom. When the registration errors and the lead times are considered, the method using the ACR-approved PET phantom was more practical and useful than the method using the NEMA IEC body phantom.

Photogrammetry and ballistic analysis of a high-flying projectile in the STS-124 space shuttle launch

NASA Astrophysics Data System (ADS)

Metzger, Philip T.; Lane, John E.; Carilli, Robert A.; Long, Jason M.; Shawn, Kathy L.

2010-07-01

A method combining photogrammetry with ballistic analysis is demonstrated to identify flying debris in a rocket launch environment. Debris traveling near the STS-124 Space Shuttle was captured on cameras viewing the launch pad within the first few seconds after launch. One particular piece of debris caught the attention of investigators studying the release of flame trench fire bricks because its high trajectory could indicate a flight risk to the Space Shuttle. Digitized images from two pad perimeter high-speed 16-mm film cameras were processed using photogrammetry software based on a multi-parameter optimization technique. Reference points in the image were found from 3D CAD models of the launch pad and from surveyed points on the pad. The three-dimensional reference points were matched to the equivalent two-dimensional camera projections by optimizing the camera model parameters using a gradient search optimization technique. Using this method of solving the triangulation problem, the xyz position of the object's path relative to the reference point coordinate system was found for every set of synchronized images. This trajectory was then compared to a predicted trajectory while performing regression analysis on the ballistic coefficient and other parameters. This identified, with a high degree of confidence, the object's material density and thus its probable origin within the launch pad environment. Future extensions of this methodology may make it possible to diagnose the underlying causes of debris-releasing events in near-real time, thus improving flight safety.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guney, Ali; Poyraz, M. Ibrahim; Kangal, Olgac, E-mail: kangal@itu.edu.tr

Highlights: • Both PET and PVC have nearly the same densities. • The best pH value will be 4 for optimizing pH values. • Malic acid gave the best results for selective separation of PET and PVC. - Abstract: Plastics have become the widely used materials because of their advantages, such as cheapness, endurance, lightness, and hygiene. However, they cause waste and soil pollution and they do not easily decompose. Many promising technologies are being investigated for separating mixed thermoplastics, but they are still uneconomical and unreliable. Depending on their surface characteristics, these plastics can be separated from each othermore » by flotation method which is useful mineral processing technique with its low cost and simplicity. The main objective of this study is to investigate the flotation characteristics of PET and PVC and determine the effect of plasticizer reagents on efficient plastic separation. For that purpose, various parameters such as pH, plasticizer concentration, plasticizer type, conditioning temperature and thermal conditioning were investigated. As a result, PET particles were floated with 95.1% purity and 65.3% efficiency while PVC particles were obtained with 98.1% purity and 65.3% efficiency.« less

[Prokaryotic expression, purification and antigenicity identification of recombinant human survivin protein].

PubMed

Yin, Xiaotao; Wang, Wei; Tian, Renli; Xu, Yuanji; Yan, Jinqi; Zhang, Wei; Gao, Jiangping; Yu, Jiyun

2013-08-01

To construct a prokaryotic expression plasmid pET28a-survivin, optimize the recombinant protein expression conditions in E.coli, and purify the survivin recombinant protein and identify its antigenicity. Survivin cDNA segment was amplified by PCR and cloned into prokaryotic expression vector pET28a(+) to construct the recombinant expression vector pET28a-survivin. The expression vector was transformed into BL21 (DE3) and the fusion protein survivin/His was induced by IPTG. The fusion protein was purified through Ni affinity chromatography. The antigenicity of the purified survivin protein was identified by Western blotting and ELISA. The recombinant expression vector was verified successfully by BamHI and HindIII. The fusion protein induced by IPTG was obtained with Mr; about 24 000. The purity of the purified protein reached 90% by SDS-PAGE analysis. And the antigenicity of the survivin protein was validated by Western blotting and ELISA. The prokaryotic expression plasmid pET28a-survivin was successfully constructed and the survivin protein was expressed and purified in E.coli. The antigenicity of the purified survivin protein was demonstrated desirable.

Acceleration of the direct reconstruction of linear parametric images using nested algorithms.

PubMed

Wang, Guobao; Qi, Jinyi

2010-03-07

Parametric imaging using dynamic positron emission tomography (PET) provides important information for biological research and clinical diagnosis. Indirect and direct methods have been developed for reconstructing linear parametric images from dynamic PET data. Indirect methods are relatively simple and easy to implement because the image reconstruction and kinetic modeling are performed in two separate steps. Direct methods estimate parametric images directly from raw PET data and are statistically more efficient. However, the convergence rate of direct algorithms can be slow due to the coupling between the reconstruction and kinetic modeling. Here we present two fast gradient-type algorithms for direct reconstruction of linear parametric images. The new algorithms decouple the reconstruction and linear parametric modeling at each iteration by employing the principle of optimization transfer. Convergence speed is accelerated by running more sub-iterations of linear parametric estimation because the computation cost of the linear parametric modeling is much less than that of the image reconstruction. Computer simulation studies demonstrated that the new algorithms converge much faster than the traditional expectation maximization (EM) and the preconditioned conjugate gradient algorithms for dynamic PET.

Diagnostic and clinical benefit of combined coronary calcium and perfusion assessment in patients undergoing PET/CT myocardial perfusion stress imaging.

PubMed

Bybee, Kevin A; Lee, John; Markiewicz, Richard; Longmore, Ryan; McGhie, A Iain; O'Keefe, James H; Hsu, Bai-Ling; Kennedy, Kevin; Thompson, Randall C; Bateman, Timothy M

2010-04-01

A limitation of stress myocardial perfusion imaging (MPI) is the inability to detect non-obstructive coronary artery disease (CAD). One advantage of MPI with a hybrid CT device is the ability to obtain same-setting measurement of the coronary artery calcium score (CACS). Utilizing our single-center nuclear database, we identified 760 consecutive patients with: (1) no CAD history; (2) a normal clinically indicated Rb-82 PET/CT stress perfusion study; and (3) a same-setting CAC scan. 487 of 760 patients (64.1%) had subclinical CAD based on an abnormal CACS. Of those with CAC, the CACS was > or =100, > or =400, and > or =1000 in 47.0%, 22.4%, and 8.4% of patients, respectively. Less than half of the patients with CAC were receiving aspirin or statin medications prior to PET/CT imaging. Patients with CAC were more likely to be initiated or optimized on proven medical therapy for CAD immediately following PET/CT MPI compared to those without CAC. Subclinical CAD is common in patients without known CAD and normal myocardial perfusion assessed by hybrid PET/CT imaging. Identification of CAC influences subsequent physician prescribing patterns such that those with CAC are more likely to be treated with proven medical therapy for the treatment of CAD.

Physics process level discrimination of detections for GATE: assessment of contamination in SPECT and spurious activity in PET.

PubMed

De Beenhouwer, Jan; Staelens, Steven; Vandenberghe, Stefaan; Verhaeghe, Jeroen; Van Holen, Roel; Rault, Erwann; Lemahieu, Ignace

2009-04-01

The GEANT4 application for tomographic emission (GATE) is one of the most detailed Monte Carlo simulation tools for SPECT and PET. It allows for realistic phantoms, complex decay schemes, and a large variety of detector geometries. However, only a fraction of the information in each particle history is available for postprocessing. In order to extend the analysis capabilities of GATE, a flexible framework was developed. This framework allows all detected events to be subdivided according to their type: In PET, true coincidences from others, and in SPECT, geometrically collimated photons from others. The framework of the authors can be applied to any isotope, phantom, and detector geometry available in GATE. It is designed to enhance the usability of GATE for the study of contamination and for the investigation of the properties of current and future prototype detectors. The authors apply the framework to a case study of Bexxar, first assuming labeling with 124I, then with 131I. It is shown that with 124I PET, results with an optimized window improve upon those with the standard window but achieve less than half of the ideal improvement. Nevertheless, 124I PET shows improved resolution compared to 131I SPECT with triple-energy-window scatter correction.

It's a question of endurance - Patients with head and neck cancer experiences of 18F-FDG PET/CT in a fixation mask.

PubMed

Andersson, Camilla; Röing, Marta; Tiblom Ehrsson, Ylva; Johansson, Birgitta

2017-08-01

This study aimed to explore how patients with head and neck cancer experienced undergoing an 18 F-fluoro-deoxy-glucose positrons emissions tomography/computed tomography ( 18 F-FDG PET/CT) examination in a fixation mask. Interviews were conducted with nine patients with known or suspected head and neck cancer who were scheduled for the examination for the first time. The phenomenological method according to van Manen and his four lifeworld existentials; lived space, lived body, lived time, and lived relation was used to analyse the interviews. The thoughts and feelings of the patients during the PET/CT examination varied, some found it very difficult, while others did not. However, for all the patients, it was an experience that required some form of coping to maintain composure for example distraction. PET/CT examnation in a fixation mask may be strenuous for some patients. Patients need more detailed information, including suggestions for coping behaviours, prior to the examination, as well as higher level of support during and after the examination. The results of this study may be used to improve patient care and optimize the procedure of PET/CT examination in a fixation mask. Copyright © 2017 Elsevier Ltd. All rights reserved.

Next generation PET data acquisition architectures

NASA Astrophysics Data System (ADS)

Jones, W. F.; Reed, J. H.; Everman, J. L.; Young, J. W.; Seese, R. D.

1997-06-01

New architectures for higher performance data acquisition in PET are proposed. Improvements are demanded primarily by three areas of advancing PET state of the art. First, larger detector arrays such as the Hammersmith ECAT/sup (R/) EXACT HR/sup ++/ exceed the addressing capacity of 32 bit coincidence event words. Second, better scintillators (LSO) make depth-of interaction (DOI) and time-of-flight (TOF) operation more practical. Third, fully optimized single photon attenuation correction requires higher rates of data collection. New technologies which enable the proposed third generation Real Time Sorter (RTS III) include: (1) 80 Mbyte/sec Fibre Channel RAID disk systems, (2) PowerPC on both VMEbus and PCI Local bus, and (3) quadruple interleaved DRAM controller designs. Data acquisition flexibility is enhanced through a wider 64 bit coincidence event word. PET methodology support includes DOI (6 bits), TOF (6 bits), multiple energy windows (6 bits), 512/spl times/512 sinogram indexes (18 bits), and 256 crystal rings (16 bits). Throughput of 10 M events/sec is expected for list-mode data collection as well as both on-line and replay histogramming. Fully efficient list-mode storage for each PET application is provided by real-time bit packing of only the active event word bits. Real-time circuits provide DOI rebinning.

Vision 20/20: Simultaneous CT-MRI — Next chapter of multimodality imaging

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Ge, E-mail: wangg6@rpi.edu; Xi, Yan; Gjesteby, Lars

Multimodality imaging systems such as positron emission tomography-computed tomography (PET-CT) and MRI-PET are widely available, but a simultaneous CT-MRI instrument has not been developed. Synergies between independent modalities, e.g., CT, MRI, and PET/SPECT can be realized with image registration, but such postprocessing suffers from registration errors that can be avoided with synchronized data acquisition. The clinical potential of simultaneous CT-MRI is significant, especially in cardiovascular and oncologic applications where studies of the vulnerable plaque, response to cancer therapy, and kinetic and dynamic mechanisms of targeted agents are limited by current imaging technologies. The rationale, feasibility, and realization of simultaneous CT-MRImore » are described in this perspective paper. The enabling technologies include interior tomography, unique gantry designs, open magnet and RF sequences, and source and detector adaptation. Based on the experience with PET-CT, PET-MRI, and MRI-LINAC instrumentation where hardware innovation and performance optimization were instrumental to construct commercial systems, the authors provide top-level concepts for simultaneous CT-MRI to meet clinical requirements and new challenges. Simultaneous CT-MRI fills a major gap of modality coupling and represents a key step toward the so-called “omnitomography” defined as the integration of all relevant imaging modalities for systems biology and precision medicine.« less

Optimization of transition edge sensor arrays for cosmic microwave background observations with the south pole telescope

DOE PAGES

Ding, Junjia; Ade, P. A. R.; Anderson, A. J.; ...

2016-12-15

In this study, we describe the optimization of transition-edge-sensor (TES) detector arrays for the thirdgeneration camera for the South PoleTelescope.The camera,which contains ~16 000 detectors, will make high-angular-resolution maps of the temperature and polarization of the cosmic microwave background. Our key results are scatter in the transition temperature of Ti/Au TESs is reduced by fabricating the TESs on a thin Ti(5 nm)/Au(5 nm) buffer layer and the thermal conductivity of the legs that support our detector islands is dominated by the SiOx dielectric in the microstrip transmission lines that run along

Simulative design and process optimization of the two-stage stretch-blow molding process

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hopmann, Ch.; Rasche, S.; Windeck, C.

2015-05-22

The total production costs of PET bottles are significantly affected by the costs of raw material. Approximately 70 % of the total costs are spent for the raw material. Therefore, stretch-blow molding industry intends to reduce the total production costs by an optimized material efficiency. However, there is often a trade-off between an optimized material efficiency and required product properties. Due to a multitude of complex boundary conditions, the design process of new stretch-blow molded products is still a challenging task and is often based on empirical knowledge. Application of current CAE-tools supports the design process by reducing development timemore » and costs. This paper describes an approach to determine optimized preform geometry and corresponding process parameters iteratively. The wall thickness distribution and the local stretch ratios of the blown bottle are calculated in a three-dimensional process simulation. Thereby, the wall thickness distribution is correlated with an objective function and preform geometry as well as process parameters are varied by an optimization algorithm. Taking into account the correlation between material usage, process history and resulting product properties, integrative coupled simulation steps, e.g. structural analyses or barrier simulations, are performed. The approach is applied on a 0.5 liter PET bottle of Krones AG, Neutraubling, Germany. The investigations point out that the design process can be supported by applying this simulative optimization approach. In an optimization study the total bottle weight is reduced from 18.5 g to 15.5 g. The validation of the computed results is in progress.« less

Simulative design and process optimization of the two-stage stretch-blow molding process

NASA Astrophysics Data System (ADS)

Hopmann, Ch.; Rasche, S.; Windeck, C.

2015-05-01

The total production costs of PET bottles are significantly affected by the costs of raw material. Approximately 70 % of the total costs are spent for the raw material. Therefore, stretch-blow molding industry intends to reduce the total production costs by an optimized material efficiency. However, there is often a trade-off between an optimized material efficiency and required product properties. Due to a multitude of complex boundary conditions, the design process of new stretch-blow molded products is still a challenging task and is often based on empirical knowledge. Application of current CAE-tools supports the design process by reducing development time and costs. This paper describes an approach to determine optimized preform geometry and corresponding process parameters iteratively. The wall thickness distribution and the local stretch ratios of the blown bottle are calculated in a three-dimensional process simulation. Thereby, the wall thickness distribution is correlated with an objective function and preform geometry as well as process parameters are varied by an optimization algorithm. Taking into account the correlation between material usage, process history and resulting product properties, integrative coupled simulation steps, e.g. structural analyses or barrier simulations, are performed. The approach is applied on a 0.5 liter PET bottle of Krones AG, Neutraubling, Germany. The investigations point out that the design process can be supported by applying this simulative optimization approach. In an optimization study the total bottle weight is reduced from 18.5 g to 15.5 g. The validation of the computed results is in progress.

Optimization of digitization procedures in cultural heritage preservation

NASA Astrophysics Data System (ADS)

Martínez, Bea; Mitjà, Carles; Escofet, Jaume

2013-11-01

The digitization of both volumetric and flat objects is the nowadays-preferred method in order to preserve cultural heritage items. High quality digital files obtained from photographic plates, films and prints, paintings, drawings, gravures, fabrics and sculptures, allows not only for a wider diffusion and on line transmission, but also for the preservation of the original items from future handling. Early digitization procedures used scanners for flat opaque or translucent objects and camera only for volumetric or flat highly texturized materials. The technical obsolescence of the high-end scanners and the improvement achieved by professional cameras has result in a wide use of cameras with digital back to digitize any kind of cultural heritage item. Since the lens, the digital back, the software controlling the camera and the digital image processing provide a wide range of possibilities, there is necessary to standardize the methods used in the reproduction work leading to preserve as high as possible the original item properties. This work presents an overview about methods used for camera system characterization, as well as the best procedures in order to identify and counteract the effect of the lens residual aberrations, sensor aliasing, image illumination, color management and image optimization by means of parametric image processing. As a corollary, the work shows some examples of reproduction workflow applied to the digitization of valuable art pieces and glass plate photographic black and white negatives.

A Novel Multi-Camera Calibration Method based on Flat Refractive Geometry

NASA Astrophysics Data System (ADS)

Huang, S.; Feng, M. C.; Zheng, T. X.; Li, F.; Wang, J. Q.; Xiao, L. F.

2018-03-01

Multi-camera calibration plays an important role in many field. In the paper, we present a novel multi-camera calibration method based on flat refractive geometry. All cameras can acquire calibration images of transparent glass calibration board (TGCB) at the same time. The application of TGCB leads to refractive phenomenon which can generate calibration error. The theory of flat refractive geometry is employed to eliminate the error. The new method can solve the refractive phenomenon of TGCB. Moreover, the bundle adjustment method is used to minimize the reprojection error and obtain optimized calibration results. Finally, the four-cameras calibration results of real data show that the mean value and standard deviation of the reprojection error of our method are 4.3411e-05 and 0.4553 pixel, respectively. The experimental results show that the proposed method is accurate and reliable.

HERCULES/MSI: a multispectral imager with geolocation for STS-70

NASA Astrophysics Data System (ADS)

Simi, Christopher G.; Kindsfather, Randy; Pickard, Henry; Howard, William, III; Norton, Mark C.; Dixon, Roberta

1995-11-01

A multispectral intensified CCD imager combined with a ring laser gyroscope based inertial measurement unit was flown on the Space Shuttle Discovery from July 13-22, 1995 (Space Transport System Flight No. 70, STS-70). The camera includes a six position filter wheel, a third generation image intensifier, and a CCD camera. The camera is integrated with a laser gyroscope system that determines the ground position of the imagery to an accuracy of better than three nautical miles. The camera has two modes of operation; a panchromatic mode for high-magnification imaging [ground sample distance (GSD) of 4 m], or a multispectral mode consisting of six different user-selectable spectral ranges at reduced magnification (12 m GSD). This paper discusses the system hardware and technical trade-offs involved with camera optimization, and presents imagery observed during the shuttle mission.

Collaborative real-time scheduling of multiple PTZ cameras for multiple object tracking in video surveillance

NASA Astrophysics Data System (ADS)

Liu, Yu-Che; Huang, Chung-Lin

2013-03-01

This paper proposes a multi-PTZ-camera control mechanism to acquire close-up imagery of human objects in a surveillance system. The control algorithm is based on the output of multi-camera, multi-target tracking. Three main concerns of the algorithm are (1) the imagery of human object's face for biometric purposes, (2) the optimal video quality of the human objects, and (3) minimum hand-off time. Here, we define an objective function based on the expected capture conditions such as the camera-subject distance, pan tile angles of capture, face visibility and others. Such objective function serves to effectively balance the number of captures per subject and quality of captures. In the experiments, we demonstrate the performance of the system which operates in real-time under real world conditions on three PTZ cameras.

Serotonin 2A receptor agonist binding in the human brain with [11C]Cimbi-36

PubMed Central

Ettrup, Anders; da Cunha-Bang, Sophie; McMahon, Brenda; Lehel, Szabolcs; Dyssegaard, Agnete; Skibsted, Anine W; Jørgensen, Louise M; Hansen, Martin; Baandrup, Anders O; Bache, Søren; Svarer, Claus; Kristensen, Jesper L; Gillings, Nic; Madsen, Jacob; Knudsen, Gitte M

2014-01-01

[11C]Cimbi-36 was recently developed as a selective serotonin 2A (5-HT2A) receptor agonist radioligand for positron emission tomography (PET) brain imaging. Such an agonist PET radioligand may provide a novel, and more functional, measure of the serotonergic system and agonist binding is more likely than antagonist binding to reflect 5-HT levels in vivo. Here, we show data from a first-in-human clinical trial with [11C]Cimbi-36. In 29 healthy volunteers, we found high brain uptake and distribution according to 5-HT2A receptors with [11C]Cimbi-36 PET. The two-tissue compartment model using arterial input measurements provided the most optimal quantification of cerebral [11C]Cimbi-36 binding. Reference tissue modeling was feasible as it induced a negative but predictable bias in [11C]Cimbi-36 PET outcome measures. In five subjects, pretreatment with the 5-HT2A receptor antagonist ketanserin before a second PET scan significantly decreased [11C]Cimbi-36 binding in all cortical regions with no effects in cerebellum. These results confirm that [11C]Cimbi-36 binding is selective for 5-HT2A receptors in the cerebral cortex and that cerebellum is an appropriate reference tissue for quantification of 5-HT2A receptors in the human brain. Thus, we here describe [11C]Cimbi-36 as the first agonist PET radioligand to successfully image and quantify 5-HT2A receptors in the human brain. PMID:24780897

Clinical Investigation of the Dopaminergic System with PET and FLUORINE-18-FLUORO-L-DOPA.

NASA Astrophysics Data System (ADS)

Oakes, Terrence Rayford

1995-01-01

Positron Emission Tomography (PET) is a tool that provides quantitative physiological information. It is valuable both in a clinical environment, where information is sought for an individual, and in a research environment, to answer more fundamental questions about physiology and disease states. PET is particularly attractive compared to other nuclear medicine imaging techniques in cases where the anatomical regions of interest are small or when true metabolic rate constants are required. One example with both of these requirements is the investigation of Parkinson's Disease, which is characterized as a presynaptic motor function deficit affecting the striatum. As dopaminergic neurons die, the ability of the striatum to affect motor function decreases. The extent of functional neuronal damage in the small sub-structures may be ascertained by measuring the ability of the caudate and putamen to trap and store dopamine, a neurotransmitter. PET is able to utilize a tracer of dopamine activity, ^ {18}F- scL-DOPA, to quantitate the viability of the striatum. This thesis work deals with implementing and optimizing the many different elements that compose a PET study of the dopaminergic system, including: radioisotope production; conversion of aqueous ^{18}F ^-into [^ {18}F]-F2; synthesis of ^{18}F- scL -DOPA; details of the PET scan itself; measurements to estimate the radiation dosimetry; accurate measurement of a plasma input function; and the quantitation of dopaminergic activity in normal human subjects as well as in Parkinson's Disease patients.

Differentiation and diagnosis of benign and malignant testicular lesions using 18F-FDG PET/CT.

PubMed

Shao, Dan; Gao, Qiang; Tian, Xu-Wei; Wang, Si-Yun; Liang, Chang-Hong; Wang, Shu-Xia

2017-08-01

The purpose of this study was to evaluate the differential diagnostic value of 18 F-fluorodeoxy glucose positron emission tomography/computed tomography ( 18 F-FDG PET/CT) for benign and malignant testicular lesions. The PET/CT scans of 53 patients with testicular lesions confirmed by biopsy or surgical pathology were retrospectively analyzed. There were 32 cases of malignant tumors and 21 cases of benign lesions. Differences in the maximum standardized uptake value (SUVmax) measurements and the SUVmax lesion/background ratios between benign and malignant lesions were analyzed. The diagnostic value of this PET/CT modality for the differential diagnosis of benign versus malignant testicular lesions was calculated. The differences in the SUVmax measurements and the SUVmax lesion/background ratios between benign and malignant lesions were statistically significant (SUVmax: Z=-4.295, p=0.000; SUVmax lesion/background ratio: Z=-5.219, p=0.000); specifically, both of these indicators were higher in malignant lesions compared to benign lesions. An SUVmax of 3.75 was the optimal cutoff value to differentiate between benign and malignant testicular lesions. The diagnostic sensitivity, specificity, accuracy, positive predictive value, and negative predictive value of this PET/CT modality in the differential diagnosis of benign versus malignant testicular lesions were 90.6%, 80.9%, 86.8%, 87.9%, and 85.0%, respectively. 18 F-FDG PET/CT can accurately identify benign and malignant testicular lesions. Copyright © 2017 Elsevier B.V. All rights reserved.

Enhanced RGB-D Mapping Method for Detailed 3D Indoor and Outdoor Modeling

PubMed Central

Tang, Shengjun; Zhu, Qing; Chen, Wu; Darwish, Walid; Wu, Bo; Hu, Han; Chen, Min

2016-01-01

RGB-D sensors (sensors with RGB camera and Depth camera) are novel sensing systems that capture RGB images along with pixel-wise depth information. Although they are widely used in various applications, RGB-D sensors have significant drawbacks including limited measurement ranges (e.g., within 3 m) and errors in depth measurement increase with distance from the sensor with respect to 3D dense mapping. In this paper, we present a novel approach to geometrically integrate the depth scene and RGB scene to enlarge the measurement distance of RGB-D sensors and enrich the details of model generated from depth images. First, precise calibration for RGB-D Sensors is introduced. In addition to the calibration of internal and external parameters for both, IR camera and RGB camera, the relative pose between RGB camera and IR camera is also calibrated. Second, to ensure poses accuracy of RGB images, a refined false features matches rejection method is introduced by combining the depth information and initial camera poses between frames of the RGB-D sensor. Then, a global optimization model is used to improve the accuracy of the camera pose, decreasing the inconsistencies between the depth frames in advance. In order to eliminate the geometric inconsistencies between RGB scene and depth scene, the scale ambiguity problem encountered during the pose estimation with RGB image sequences can be resolved by integrating the depth and visual information and a robust rigid-transformation recovery method is developed to register RGB scene to depth scene. The benefit of the proposed joint optimization method is firstly evaluated with the publicly available benchmark datasets collected with Kinect. Then, the proposed method is examined by tests with two sets of datasets collected in both outside and inside environments. The experimental results demonstrate the feasibility and robustness of the proposed method. PMID:27690028

Enhanced RGB-D Mapping Method for Detailed 3D Indoor and Outdoor Modeling.

PubMed

Tang, Shengjun; Zhu, Qing; Chen, Wu; Darwish, Walid; Wu, Bo; Hu, Han; Chen, Min

2016-09-27

RGB-D sensors (sensors with RGB camera and Depth camera) are novel sensing systems that capture RGB images along with pixel-wise depth information. Although they are widely used in various applications, RGB-D sensors have significant drawbacks including limited measurement ranges (e.g., within 3 m) and errors in depth measurement increase with distance from the sensor with respect to 3D dense mapping. In this paper, we present a novel approach to geometrically integrate the depth scene and RGB scene to enlarge the measurement distance of RGB-D sensors and enrich the details of model generated from depth images. First, precise calibration for RGB-D Sensors is introduced. In addition to the calibration of internal and external parameters for both, IR camera and RGB camera, the relative pose between RGB camera and IR camera is also calibrated. Second, to ensure poses accuracy of RGB images, a refined false features matches rejection method is introduced by combining the depth information and initial camera poses between frames of the RGB-D sensor. Then, a global optimization model is used to improve the accuracy of the camera pose, decreasing the inconsistencies between the depth frames in advance. In order to eliminate the geometric inconsistencies between RGB scene and depth scene, the scale ambiguity problem encountered during the pose estimation with RGB image sequences can be resolved by integrating the depth and visual information and a robust rigid-transformation recovery method is developed to register RGB scene to depth scene. The benefit of the proposed joint optimization method is firstly evaluated with the publicly available benchmark datasets collected with Kinect. Then, the proposed method is examined by tests with two sets of datasets collected in both outside and inside environments. The experimental results demonstrate the feasibility and robustness of the proposed method.

(11)C-Choline PET/CT for restaging prostate cancer. Results from 4,426 scans in a single-centre patient series.

PubMed

Graziani, Tiziano; Ceci, Francesco; Castellucci, Paolo; Polverari, Giulia; Lima, Giacomo Maria; Lodi, Filippo; Morganti, Alessio Giuseppe; Ardizzoni, Andrea; Schiavina, Riccardo; Fanti, Stefano

2016-10-01

To evaluate (11)C-choline PET/CT as a diagnostic tool for restaging prostate cancer (PCa), in a large, homogeneous and clinically relevant population of patients with biochemical recurrence (BCR) of PCa after primary therapy. The secondary aim was to assess the best timing for performing (11)C-choline PET/CT during BCR. We retrospectively analysed 9,632 (11)C-choline PET/CT scans performed in our institution for restaging PCa from January 2007 to June 2015. The inclusion criteria were: (1) proven PCa radically treated with radical prostatectomy (RP) or with primary external beam radiotherapy (EBRT); (2) PSA serum values available; (3) proven BCR (PSA >0.2 ng/mL after RP or PSA >2 ng/mL above the nadir after primary EBRT with rising PSA levels). Finally, 3,203 patients with recurrent PCa matching all the inclusion criteria were retrospectively enrolled and 4,426 scans were analysed. Overall, 52.8 % of the (11)C-choline PET/CT scans (2,337/4,426) and 54.8 % of the patients (1,755/3,203) were positive. In 29.4 % of the scans, at least one distant finding was observed. The mean and median PSA values were, respectively, 4.9 and 2.1 ng/mL at the time of the scan (range 0.2 - 50 ng/mL). In our series, 995 scans were performed in patients with PSA levels between 1 and 2 ng/mL. In this subpopulation the positivity rate in the 995 scans was 44.7 %, with an incidence of distant findings of 19.2 % and an incidence of oligometastatic disease (one to three lesions) of 37.7 %. The absolute PSA value at the time of the scan and ongoing androgen deprivation therapy were associated with an increased probability of a positive (11)C-choline PET/CT scan (p < 0.0001). In the ROC analysis, a PSA value of 1.16 ng/mL was the optimal cut-off value. In patients with a PSA value <1.16 ng/mL, 26.8 % of 1,426 (11)C-choline PET/CT scans were positive, with oligometastatic disease in 84.7 % of positive scans. In a large cohort of patients, the feasibility of (11)C-choline PET/CT for detecting the sites of metastatic disease in PCa patients with BCR was confirmed. The PSA level was the main predictor of a positive scan with 1.16 ng/mL as the optimal cut-off value. In the majority of positive scans oligometastatic disease, potentially treatable with salvage therapies, was observed.

Dynamic PET/CT measurements of induced positron activity in a prostate cancer patient after 50-MV photon radiation therapy.

PubMed

Janek Strååt, Sara; Jacobsson, Hans; Noz, Marilyn E; Andreassen, Björn; Näslund, Ingemar; Jonsson, Cathrine

2013-01-23

The purpose of this work was to reveal the research interest value of positron emission tomography (PET) imaging in visualizing the induced tissue activity post high-energy photon radiation treatment. More specifically, the focus was on the possibility of retrieving data such as tissue composition and physical half-lives from dynamic PET acquisitions, as positron-emitting radionuclides such as 15O, 11C, and 13N are produced in vivo during radiation treatment with high-energy photons (>15 MeV). The type, amount, and distribution of induced positron-emitting radionuclides depend on the irradiated tissue cross section, the photon spectrum, and the possible perfusion-driven washout. A 62-year-old man diagnosed with prostate cancer was referred for palliative radiation treatment of the pelvis minor. A total dose of 8 Gy was given using high-energy photon beams (50 MV) with a racetrack microtron, and 7 min after the end of irradiation, the patient was positioned in a PET/computed tomography (CT) camera, and a list-mode acquisition was performed for 30 min. Two volumes of interests (VOIs) were positioned on the dynamic PET/CT images, one in the urinary bladder and the other in the subcutaneous fat. Analysis of the measured relative count rate was performed in order to compute the tissue compositions and physical half-lives in the two regions. Dynamic analysis from the two VOIs showed that the decay constants of activated oxygen and carbon could be deduced. Calculation of tissue composition from analyzing the VOI containing subcutaneous fat only moderately agreed with that of the tabulated International Commission on Radiation Units & Measurements (ICRU) data of the adipose tissue. However, the same analysis for the bladder showed a good agreement with that of the tabulated ICRU data. PET can be used in visualizing the induced activity post high-energy photon radiation treatment. Despite the very low count rate in this specific application, wherein 7 min after treatment was about 5% of that of a standard 18F-FDG PET scan, the distribution of activated tissue elements (15O and 11C) could be calculated from the dynamic PET data. One possible future application of this method could possibly be to measure and determine the tumor tissue composition in order to identify any hypoxic or necrotic region, which is information that can be used in the ongoing therapy planning process. The official name of the trial committee of this study is 'Regionala etikprövningsnämnden i Stockholm' (FE 289, Stockholm, SE-17177, Sweden). The unique identifying number is 2011/1789-31/2.

Optimization of high filler loading on tensile properties of recycled HDPE/PET blends filled with rice husk

NASA Astrophysics Data System (ADS)

Chen, Ruey Shan; Ahmad, Sahrim; Ghani, Mohd Hafizuddin Ab; Salleh, Mohd Nazry

2014-09-01

Biocomposites of recycled high density polyethylene / recycled polyethylene terephthalate (rHDPE/rPET) blend incorporated with rice husk flour (RHF) were prepared using a corotating twin screw extruder. Maleic anhydride polyethylene (MAPE) was added as a coupling agent to improve the fibre-matrix interface adhesion. The effect of high filler loadings (50-90 wt%) on morphology and tensile properties of compatibilized rHDPE/rPET blend was investigated. The results of our study shown that composite with 70 wt% exhibited the highest tensile strength and Young's modulus, which are 22 MPa and 1752 MPa, respectively. The elongation at break decreased with increasing percentage of RHF. SEM micrograph confirmed fillers dispersion, morphological interaction and enhanced interfacial bonding between recycled polymer blends and rice husk. It can be concluded that the optimum RHF content is 70 wt% with maximum tensile strength.

High performance ZnO:Al films deposited on PET substrates using facing target sputtering

NASA Astrophysics Data System (ADS)

Guo, Tingting; Dong, Guobo; Gao, Fangyuan; Xiao, Yu; Chen, Qiang; Diao, Xungang

2013-10-01

ZnO:Al (ZAO) thin films have been deposited on flexible PET substrates using a plasma damage-free facing target sputtering system at room temperature. The structure, surface morphology, electrical and optical properties were investigated as a function of working power. All the samples have a highly preferred orientation of the c-axis perpendicular to the PET substrate and have a high quality surface. With increased working power, the carrier concentration changes slightly, the mobility increases at the beginning and decreases after it reaches a maximum value, in line with electrical conductivity. The figure of merit has been significantly improved with increasing of the working power. Under the optimized condition, the lowest resistivity of 1.3 × 10-3 Ω cm with a sheet resistance of 29 Ω/□ and the relative visible transmittance above 93% in the visible region were obtained.

A PET Tracer for Renal Organic Cation Transporters, ¹¹C-Metformin: Radiosynthesis and Preclinical Proof-of-Concept Studies.

PubMed

Jakobsen, Steen; Busk, Morten; Jensen, Jonas Brorson; Munk, Ole Lajord; Zois, Nora Elisabeth; Alstrup, Aage K O; Jessen, Niels; Frøkiær, Jørgen

2016-04-01

Organic cation transporters (OCTs) in the kidney proximal tubule (PT) participate in renal excretion of drugs and endogenous compounds. PT function is commonly impaired in kidney diseases, and consequently quantitative measurement of OCT function may provide an important estimate of kidney function. Metformin is a widely used drug and targets OCT type 2 located in the PT. Thus, we hypothesized that (11)C-labeled metformin would be a suitable PET tracer for quantification of renal function. (11)C-metformin was prepared by (11)C-methylation of 1-methylbiguanide. In vitro cell uptake of (11)C-metformin was studied in LLC-PK1 cells in the presence of increasing doses of unlabeled metformin. In vivo small-animal PET studies in Sprague-Dawley rats were performed at baseline and after treatment with OCT inhibitors to evaluate renal uptake of (11)C-metformin. Kidney and liver pharmacokinetics of (11)C-metformin was investigated in vivo by dynamic (11)C-metformin PET/CT in 6 anesthetized pigs, and renal clearance of (11)C-metformin was compared with renal clearance of (51)Cr-ethylenediaminetetraacetic acid (EDTA). Formation of (11)C metabolites was investigated by analysis of blood and urine samples. The radiochemical yield of (11)C-metformin was 15% ± 3% (n= 40, decay-corrected), and up to 1.5 GBq of tracer were produced with a radiochemical purity greater than 95% in less than 30 min. Dose-dependent uptake of (11)C-metformin in LLC-PK1 cells was rapid. Rat small-animal PET images showed (11)C-metformin uptake in the kidney and liver, the kinetics of which were changed after challenging animals with OCT inhibitors. In pigs, 80% of the injected metformin dose was rapidly present in the kidney, and a high dose of metformin caused a delayed renal uptake and clearance compared with baseline consistent with transporter-mediated competition. Renal clearance of (11)C-metformin was approximately 3 times the renal clearance of (51)Cr-EDTA. We successfully synthesized an (11)C-metformin tracer, and PET studies in rats and pigs showed a rapid kidney uptake from the blood and excretion into the bladder similar to other radiopharmaceuticals developed for γ-camera renography. © 2016 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

Monitoring of Tumor Growth with [(18)F]-FET PET in a Mouse Model of Glioblastoma: SUV Measurements and Volumetric Approaches.

PubMed

Holzgreve, Adrien; Brendel, Matthias; Gu, Song; Carlsen, Janette; Mille, Erik; Böning, Guido; Mastrella, Giorgia; Unterrainer, Marcus; Gildehaus, Franz J; Rominger, Axel; Bartenstein, Peter; Kälin, Roland E; Glass, Rainer; Albert, Nathalie L

2016-01-01

Noninvasive tumor growth monitoring is of particular interest for the evaluation of experimental glioma therapies. This study investigates the potential of positron emission tomography (PET) using O-(2-(18)F-fluoroethyl)-L-tyrosine ([(18)F]-FET) to determine tumor growth in a murine glioblastoma (GBM) model-including estimation of the biological tumor volume (BTV), which has hitherto not been investigated in the pre-clinical context. Fifteen GBM-bearing mice (GL261) and six control mice (shams) were investigated during 5 weeks by PET followed by autoradiographic and histological assessments. [(18)F]-FET PET was quantitated by calculation of maximum and mean standardized uptake values within a universal volume-of-interest (VOI) corrected for healthy background (SUVmax/BG, SUVmean/BG). A partial volume effect correction (PVEC) was applied in comparison to ex vivo autoradiography. BTVs obtained by predefined thresholds for VOI definition (SUV/BG: ≥1.4; ≥1.6; ≥1.8; ≥2.0) were compared to the histologically assessed tumor volume (n = 8). Finally, individual "optimal" thresholds for BTV definition best reflecting the histology were determined. In GBM mice SUVmax/BG and SUVmean/BG clearly increased with time, however at high inter-animal variability. No relevant [(18)F]-FET uptake was observed in shams. PVEC recovered signal loss of SUVmean/BG assessment in relation to autoradiography. BTV as estimated by predefined thresholds strongly differed from the histology volume. Strikingly, the individual "optimal" thresholds for BTV assessment correlated highly with SUVmax/BG (ρ = 0.97, p < 0.001), allowing SUVmax/BG-based calculation of individual thresholds. The method was verified by a subsequent validation study (n = 15, ρ = 0.88, p < 0.01) leading to extensively higher agreement of BTV estimations when compared to histology in contrast to predefined thresholds. [(18)F]-FET PET with standard SUV measurements is feasible for glioma imaging in the GBM mouse model. PVEC is beneficial to improve accuracy of [(18)F]-FET PET SUV quantification. Although SUVmax/BG and SUVmean/BG increase during the disease course, these parameters do not correlate with the respective tumor size. For the first time, we propose a histology-verified method allowing appropriate individual BTV estimation for volumetric in vivo monitoring of tumor growth with [(18)F]-FET PET and show that standardized thresholds from routine clinical practice seem to be inappropriate for BTV estimation in the GBM mouse model.

Dual-isotope PET using positron-gamma emitters.

PubMed

Andreyev, A; Celler, A

2011-07-21

Positron emission tomography (PET) is widely recognized as a highly effective functional imaging modality. Unfortunately, standard PET cannot be used for dual-isotope imaging (which would allow for simultaneous investigation of two different biological processes), because positron-electron annihilation products from different tracers are indistinguishable in terms of energy. Methods that have been proposed for dual-isotope PET rely on differences in half-lives of the participating isotopes; these approaches, however, require making assumptions concerning kinetic behavior of the tracers and may not lead to optimal results. In this paper we propose a novel approach for dual-isotope PET and investigate its performance using GATE simulations. Our method requires one of the two radioactive isotopes to be a pure positron emitter and the second isotope to emit an additional high-energy gamma in a cascade simultaneously with positron emission. Detection of this auxiliary prompt gamma in coincidence with the annihilation event allows us to identify the corresponding 511 keV photon pair as originating from the same isotope. Two list-mode datasets are created: a primary dataset that contains all detected 511 keV photon pairs from both isotopes, and a second, tagged (much smaller) dataset that contains only those PET events for which a coincident prompt gamma has also been detected. An image reconstructed from the tagged dataset reflects the distribution of the second positron-gamma radiotracer and serves as a prior for the reconstruction of the primary dataset. Our preliminary simulation study with partially overlapping (18)F/(22)Na and (18)F/(60)Cu radiotracer distributions showed that in these two cases the dual-isotope PET method allowed for separation of the two activity distributions and recovered total activities with relative errors of about 5%.

High Resolution PET with 250 micrometer LSO Detectors and Adaptive Zoom

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cherry, Simon R.; Qi, Jinyi

2012-01-08

There have been impressive improvements in the performance of small-animal positron emission tomography (PET) systems since their first development in the mid 1990s, both in terms of spatial resolution and sensitivity, which have directly contributed to the increasing adoption of this technology for a wide range of biomedical applications. Nonetheless, current systems still are largely dominated by the size of the scintillator elements used in the detector. Our research predicts that developing scintillator arrays with an element size of 250 {micro}m or smaller will lead to an image resolution of 500 {micro}m when using 18F- or 64Cu-labeled radiotracers, giving amore » factor of 4-8 improvement in volumetric resolution over the highest resolution research systems currently in existence. This proposal had two main objectives: (i) To develop and evaluate much higher resolution and efficiency scintillator arrays that can be used in the future as the basis for detectors in a small-animal PET scanner where the spatial resolution is dominated by decay and interaction physics rather than detector size. (ii) To optimize one such high resolution, high sensitivity detector and adaptively integrate it into the existing microPET II small animal PET scanner as a 'zoom-in' detector that provides higher spatial resolution and sensitivity in a limited region close to the detector face. The knowledge gained from this project will provide valuable information for building future PET systems with a complete ring of very high-resolution detector arrays and also lay the foundations for utilizing high-resolution detectors in combination with existing PET systems for localized high-resolution imaging.« less

Region specific optimization of continuous linear attenuation coefficients based on UTE (RESOLUTE): application to PET/MR brain imaging

NASA Astrophysics Data System (ADS)

Ladefoged, Claes N.; Benoit, Didier; Law, Ian; Holm, Søren; Kjær, Andreas; Højgaard, Liselotte; Hansen, Adam E.; Andersen, Flemming L.

2015-10-01

The reconstruction of PET brain data in a PET/MR hybrid scanner is challenging in the absence of transmission sources, where MR images are used for MR-based attenuation correction (MR-AC). The main challenge of MR-AC is to separate bone and air, as neither have a signal in traditional MR images, and to assign the correct linear attenuation coefficient to bone. The ultra-short echo time (UTE) MR sequence was proposed as a basis for MR-AC as this sequence shows a small signal in bone. The purpose of this study was to develop a new clinically feasible MR-AC method with patient specific continuous-valued linear attenuation coefficients in bone that provides accurate reconstructed PET image data. A total of 164 [18F]FDG PET/MR patients were included in this study, of which 10 were used for training. MR-AC was based on either standard CT (reference), UTE or our method (RESOLUTE). The reconstructed PET images were evaluated in the whole brain, as well as regionally in the brain using a ROI-based analysis. Our method segments air, brain, cerebral spinal fluid, and soft tissue voxels on the unprocessed UTE TE images, and uses a mapping of R2* values to CT Hounsfield Units (HU) to measure the density in bone voxels. The average error of our method in the brain was 0.1% and less than 1.2% in any region of the brain. On average 95% of the brain was within  ±10% of PETCT, compared to 72% when using UTE. The proposed method is clinically feasible, reducing both the global and local errors on the reconstructed PET images, as well as limiting the number and extent of the outliers.

Using multi-disciplinary optimization and numerical simulation on the transiting exoplanet survey satellite

NASA Astrophysics Data System (ADS)

Stoeckel, Gerhard P.; Doyle, Keith B.

2017-08-01

The Transiting Exoplanet Survey Satellite (TESS) is an instrument consisting of four, wide fieldof- view CCD cameras dedicated to the discovery of exoplanets around the brightest stars, and understanding the diversity of planets and planetary systems in our galaxy. Each camera utilizes a seven-element lens assembly with low-power and low-noise CCD electronics. Advanced multivariable optimization and numerical simulation capabilities accommodating arbitrarily complex objective functions have been added to the internally developed Lincoln Laboratory Integrated Modeling and Analysis Software (LLIMAS) and used to assess system performance. Various optical phenomena are accounted for in these analyses including full dn/dT spatial distributions in lenses and charge diffusion in the CCD electronics. These capabilities are utilized to design CCD shims for thermal vacuum chamber testing and flight, and verify comparable performance in both environments across a range of wavelengths, field points and temperature distributions. Additionally, optimizations and simulations are used for model correlation and robustness optimizations.

Novel Bispecific PSMA/GRPr Targeting Radioligands with Optimized Pharmacokinetics for Improved PET Imaging of Prostate Cancer.

PubMed

Liolios, C; Schäfer, M; Haberkorn, U; Eder, M; Kopka, K

2016-03-16

A new series of bispecific radioligands (BRLs) targeting prostate-specific membrane antigen (PSMA) and gastrin releasing peptide receptor (GRPr), both expressed on prostate cancer cells, was developed. Their design was based on the bombesin (BN) analogue, H2N-PEG2-[D-Tyr(6),β-Ala(11),Thi(13),Nle(14)]BN(6-14), which binds to GRPr with high affinity and specificity, and the peptidomimetic urea-based pseudoirreversible inhibitor of PSMA, Glu-ureido-Lys. The two pharmacophores were coupled through copper(I)-catalyzed azide-alkyne cycloaddition to the bis(tetrafluorophenyl) ester of the chelating agent HBED-CC via amino acid linkers made of positively charged His (H) and negatively charged Glu (E): -(HE)n- (n = 0-3). The BRLs were labeled with (68)Ga, and their preliminary pharmacological properties were evaluated in vitro (competitive and time kinetic binding assays) on prostate cancer (PC-3, LNCaP) and rat pancreatic (AR42J) cell lines and in vivo by biodistribution and small animal PET imaging studies in both normal and tumor-bearing mice. The IC50/Ki values determined for all BRLs essentially matched those of the respective monomers. The maximal cellular uptake of the BLRs was observed between 20 and 30 min. The BRLs showed a synergistic ability in vivo by targeting both PSMA (LNCaP) and GRPr (PC-3) positive tumors, whereas the charged -(HE)n- (n = 1-3) linkers significantly reduced the kidney and spleen uptake. The bispecific (PSMA and GRPr) targeting ability and optimized pharmacokinetics of the compounds developed in this study could lead to their future application in clinical practice as more sensitive radiotracers for noninvasive imaging of prostate cancer (PCa) by PET/CT and PET/MRI.

Implementation and performance of shutterless uncooled micro-bolometer cameras

NASA Astrophysics Data System (ADS)

Das, J.; de Gaspari, D.; Cornet, P.; Deroo, P.; Vermeiren, J.; Merken, P.

2015-06-01

A shutterless algorithm is implemented into the Xenics LWIR thermal cameras and modules. Based on a calibration set and a global temperature coefficient the optimal non-uniformity correction is calculated onboard of the camera. The limited resources in the camera require a compact algorithm, hence the efficiency of the coding is important. The performance of the shutterless algorithm is studied by a comparison of the residual non-uniformity (RNU) and signal-to-noise ratio (SNR) between the shutterless and shuttered correction algorithm. From this comparison we conclude that the shutterless correction is only slightly less performant compared to the standard shuttered algorithm, making this algorithm very interesting for thermal infrared applications where small weight and size, and continuous operation are important.

Design and verification for front mirror-body structure of on-axis three mirror anastigmatic space camera

NASA Astrophysics Data System (ADS)

Wang, Xiaoyong; Guo, Chongling; Hu, Yongli; He, Hongyan

2017-11-01

The primary and secondary mirrors of onaxis three mirror anastigmatic (TMA) space camera are connected and supported by its front mirror-body structure, which affects both imaging performance and stability of the camera. In this paper, the carbon fiber reinforced plastics (CFRP) thin-walled cylinder and titanium alloy connecting rod have been used for the front mirror-body opto-mechanical structure of the long-focus on-axis and TMA space camera optical system. The front mirror-body component structure has then been optimized by finite element analysis (FEA) computing. Each performance of the front mirror-body structure has been tested by mechanics and vacuum experiments in order to verify the validity of such structure engineering design.

Distributed Sensing and Processing for Multi-Camera Networks

NASA Astrophysics Data System (ADS)

Sankaranarayanan, Aswin C.; Chellappa, Rama; Baraniuk, Richard G.

Sensor networks with large numbers of cameras are becoming increasingly prevalent in a wide range of applications, including video conferencing, motion capture, surveillance, and clinical diagnostics. In this chapter, we identify some of the fundamental challenges in designing such systems: robust statistical inference, computationally efficiency, and opportunistic and parsimonious sensing. We show that the geometric constraints induced by the imaging process are extremely useful for identifying and designing optimal estimators for object detection and tracking tasks. We also derive pipelined and parallelized implementations of popular tools used for statistical inference in non-linear systems, of which multi-camera systems are examples. Finally, we highlight the use of the emerging theory of compressive sensing in reducing the amount of data sensed and communicated by a camera network.

Optimizing read-out of the NECTAr front-end electronics

NASA Astrophysics Data System (ADS)

Vorobiov, S.; Feinstein, F.; Bolmont, J.; Corona, P.; Delagnes, E.; Falvard, A.; Gascón, D.; Glicenstein, J.-F.; Naumann, C. L.; Nayman, P.; Ribo, M.; Sanuy, A.; Tavernet, J.-P.; Toussenel, F.; Vincent, P.

2012-12-01

We describe the optimization of the read-out specifications of the NECTAr front-end electronics for the Cherenkov Telescope Array (CTA). The NECTAr project aims at building and testing a demonstrator module of a new front-end electronics design, which takes an advantage of the know-how acquired while building the cameras of the CAT, H.E.S.S.-I and H.E.S.S.-II experiments. The goal of the optimization work is to define the specifications of the digitizing electronics of a CTA camera, in particular integration time window, sampling rate, analog bandwidth using physics simulations. We employed for this work real photomultiplier pulses, sampled at 100 ps with a 600 MHz bandwidth oscilloscope. The individual pulses are drawn randomly at the times at which the photo-electrons, originating from atmospheric showers, arrive at the focal planes of imaging atmospheric Cherenkov telescopes. The timing information is extracted from the existing CTA simulations on the GRID and organized in a local database, together with all the relevant physical parameters (energy, primary particle type, zenith angle, distance from the shower axis, pixel offset from the optical axis, night-sky background level, etc.), and detector configurations (telescope types, camera/mirror configurations, etc.). While investigating the parameter space, an optimal pixel charge integration time window, which minimizes relative error in the measured charge, has been determined. This will allow to gain in sensitivity and to lower the energy threshold of CTA telescopes. We present results of our optimizations and first measurements obtained using the NECTAr demonstrator module.

Geometric Calibration and Validation of Ultracam Aerial Sensors

NASA Astrophysics Data System (ADS)

Gruber, Michael; Schachinger, Bernhard; Muick, Marc; Neuner, Christian; Tschemmernegg, Helfried

2016-03-01

We present details of the calibration and validation procedure of UltraCam Aerial Camera systems. Results from the laboratory calibration and from validation flights are presented for both, the large format nadir cameras and the oblique cameras as well. Thus in this contribution we show results from the UltraCam Eagle and the UltraCam Falcon, both nadir mapping cameras, and the UltraCam Osprey, our oblique camera system. This sensor offers a mapping grade nadir component together with the four oblique camera heads. The geometric processing after the flight mission is being covered by the UltraMap software product. Thus we present details about the workflow as well. The first part consists of the initial post-processing which combines image information as well as camera parameters derived from the laboratory calibration. The second part, the traditional automated aerial triangulation (AAT) is the step from single images to blocks and enables an additional optimization process. We also present some special features of our software, which are designed to better support the operator to analyze large blocks of aerial images and to judge the quality of the photogrammetric set-up.

Volume reconstruction optimization for tomo-PIV algorithms applied to experimental data

NASA Astrophysics Data System (ADS)

Martins, Fabio J. W. A.; Foucaut, Jean-Marc; Thomas, Lionel; Azevedo, Luis F. A.; Stanislas, Michel

2015-08-01

Tomographic PIV is a three-component volumetric velocity measurement technique based on the tomographic reconstruction of a particle distribution imaged by multiple camera views. In essence, the performance and accuracy of this technique is highly dependent on the parametric adjustment and the reconstruction algorithm used. Although synthetic data have been widely employed to optimize experiments, the resulting reconstructed volumes might not have optimal quality. The purpose of the present study is to offer quality indicators that can be applied to data samples in order to improve the quality of velocity results obtained by the tomo-PIV technique. The methodology proposed can potentially lead to significantly reduction in the time required to optimize a tomo-PIV reconstruction, also leading to better quality velocity results. Tomo-PIV data provided by a six-camera turbulent boundary-layer experiment were used to optimize the reconstruction algorithms according to this methodology. Velocity statistics measurements obtained by optimized BIMART, SMART and MART algorithms were compared with hot-wire anemometer data and velocity measurement uncertainties were computed. Results indicated that BIMART and SMART algorithms produced reconstructed volumes with equivalent quality as the standard MART with the benefit of reduced computational time.

Next-generation digital camera integration and software development issues

NASA Astrophysics Data System (ADS)

Venkataraman, Shyam; Peters, Ken; Hecht, Richard

1998-04-01

This paper investigates the complexities associated with the development of next generation digital cameras due to requirements in connectivity and interoperability. Each successive generation of digital camera improves drastically in cost, performance, resolution, image quality and interoperability features. This is being accomplished by advancements in a number of areas: research, silicon, standards, etc. As the capabilities of these cameras increase, so do the requirements for both hardware and software. Today, there are two single chip camera solutions in the market including the Motorola MPC 823 and LSI DCAM- 101. Real time constraints for a digital camera may be defined by the maximum time allowable between capture of images. Constraints in the design of an embedded digital camera include processor architecture, memory, processing speed and the real-time operating systems. This paper will present the LSI DCAM-101, a single-chip digital camera solution. It will present an overview of the architecture and the challenges in hardware and software for supporting streaming video in such a complex device. Issues presented include the development of the data flow software architecture, testing and integration on this complex silicon device. The strategy for optimizing performance on the architecture will also be presented.

An autonomous sensor module based on a legacy CCTV camera

NASA Astrophysics Data System (ADS)

Kent, P. J.; Faulkner, D. A. A.; Marshall, G. F.

2016-10-01

A UK MoD funded programme into autonomous sensors arrays (SAPIENT) has been developing new, highly capable sensor modules together with a scalable modular architecture for control and communication. As part of this system there is a desire to also utilise existing legacy sensors. The paper reports upon the development of a SAPIENT-compliant sensor module using a legacy Close-Circuit Television (CCTV) pan-tilt-zoom (PTZ) camera. The PTZ camera sensor provides three modes of operation. In the first mode, the camera is automatically slewed to acquire imagery of a specified scene area, e.g. to provide "eyes-on" confirmation for a human operator or for forensic purposes. In the second mode, the camera is directed to monitor an area of interest, with zoom level automatically optimized for human detection at the appropriate range. Open source algorithms (using OpenCV) are used to automatically detect pedestrians; their real world positions are estimated and communicated back to the SAPIENT central fusion system. In the third mode of operation a "follow" mode is implemented where the camera maintains the detected person within the camera field-of-view without requiring an end-user to directly control the camera with a joystick.

Partial volume correction of PET-imaged tumor heterogeneity using expectation maximization with a spatially varying point spread function

PubMed Central

Barbee, David L; Flynn, Ryan T; Holden, James E; Nickles, Robert J; Jeraj, Robert

2010-01-01

Tumor heterogeneities observed in positron emission tomography (PET) imaging are frequently compromised of partial volume effects which may affect treatment prognosis, assessment, or future implementations such as biologically optimized treatment planning (dose painting). This paper presents a method for partial volume correction of PET-imaged heterogeneous tumors. A point source was scanned on a GE Discover LS at positions of increasing radii from the scanner’s center to obtain the spatially varying point spread function (PSF). PSF images were fit in three dimensions to Gaussian distributions using least squares optimization. Continuous expressions were devised for each Gaussian width as a function of radial distance, allowing for generation of the system PSF at any position in space. A spatially varying partial volume correction (SV-PVC) technique was developed using expectation maximization (EM) and a stopping criterion based on the method’s correction matrix generated for each iteration. The SV-PVC was validated using a standard tumor phantom and a tumor heterogeneity phantom, and was applied to a heterogeneous patient tumor. SV-PVC results were compared to results obtained from spatially invariant partial volume correction (SINV-PVC), which used directionally uniform three dimensional kernels. SV-PVC of the standard tumor phantom increased the maximum observed sphere activity by 55 and 40% for 10 and 13 mm diameter spheres, respectively. Tumor heterogeneity phantom results demonstrated that as net changes in the EM correction matrix decreased below 35%, further iterations improved overall quantitative accuracy by less than 1%. SV-PVC of clinically observed tumors frequently exhibited changes of ±30% in regions of heterogeneity. The SV-PVC method implemented spatially varying kernel widths and automatically determined the number of iterations for optimal restoration, parameters which are arbitrarily chosen in SINV-PVC. Comparing SV-PVC to SINV-PVC demonstrated that similar results could be reached using both methods, but large differences result for the arbitrary selection of SINV-PVC parameters. The presented SV-PVC method was performed without user intervention, requiring only a tumor mask as input. Research involving PET-imaged tumor heterogeneity should include correcting for partial volume effects to improve the quantitative accuracy of results. PMID:20009194

Plenoptic camera wavefront sensing with extended sources

NASA Astrophysics Data System (ADS)

Jiang, Pengzhi; Xu, Jieping; Liang, Yonghui; Mao, Hongjun

2016-09-01

The wavefront sensor is used in adaptive optics to detect the atmospheric distortion, which feeds back to the deformable mirror to compensate for this distortion. Different from the Shack-Hartmann sensor that has been widely used with point sources, the plenoptic camera wavefront sensor has been proposed as an alternative wavefront sensor adequate for extended objects in recent years. In this paper, the plenoptic camera wavefront sensing with extended sources is discussed systematically. Simulations are performed to investigate the wavefront measurement error and the closed-loop performance of the plenoptic sensor. The results show that there are an optimal lenslet size and an optimal number of pixels to make the best performance. The RMS of the resulting corrected wavefront in closed-loop adaptive optics system is less than 108 nm (0.2λ) when D/r0 ≤ 10 and the magnitude M ≤ 5. Our investigation indicates that the plenoptic sensor is efficient to operate on extended sources in the closed-loop adaptive optics system.

Calibration of stereo rigs based on the backward projection process

NASA Astrophysics Data System (ADS)

Gu, Feifei; Zhao, Hong; Ma, Yueyang; Bu, Penghui; Zhao, Zixin

2016-08-01

High-accuracy 3D measurement based on binocular vision system is heavily dependent on the accurate calibration of two rigidly-fixed cameras. In most traditional calibration methods, stereo parameters are iteratively optimized through the forward imaging process (FIP). However, the results can only guarantee the minimal 2D pixel errors, but not the minimal 3D reconstruction errors. To address this problem, a simple method to calibrate a stereo rig based on the backward projection process (BPP) is proposed. The position of a spatial point can be determined separately from each camera by planar constraints provided by the planar pattern target. Then combined with pre-defined spatial points, intrinsic and extrinsic parameters of the stereo-rig can be optimized by minimizing the total 3D errors of both left and right cameras. An extensive performance study for the method in the presence of image noise and lens distortions is implemented. Experiments conducted on synthetic and real data demonstrate the accuracy and robustness of the proposed method.

Camera calibration based on the back projection process

NASA Astrophysics Data System (ADS)

Gu, Feifei; Zhao, Hong; Ma, Yueyang; Bu, Penghui

2015-12-01

Camera calibration plays a crucial role in 3D measurement tasks of machine vision. In typical calibration processes, camera parameters are iteratively optimized in the forward imaging process (FIP). However, the results can only guarantee the minimum of 2D projection errors on the image plane, but not the minimum of 3D reconstruction errors. In this paper, we propose a universal method for camera calibration, which uses the back projection process (BPP). In our method, a forward projection model is used to obtain initial intrinsic and extrinsic parameters with a popular planar checkerboard pattern. Then, the extracted image points are projected back into 3D space and compared with the ideal point coordinates. Finally, the estimation of the camera parameters is refined by a non-linear function minimization process. The proposed method can obtain a more accurate calibration result, which is more physically useful. Simulation and practical data are given to demonstrate the accuracy of the proposed method.

In vivo quantitative imaging of photoassimilate transport dynamics and allocation in large plants using a commercial positron emission tomography (PET) scanner

DOE Office of Scientific and Technical Information (OSTI.GOV)

Karve, Abhijit A.; Alexoff, David; Kim, Dohyun

Although important aspects of whole-plant carbon allocation in crop plants (e.g., to grain) occur late in development when the plants are large, techniques to study carbon transport and allocation processes have not been adapted for large plants. Positron emission tomography (PET), developed for dynamic imaging in medicine, has been applied in plant studies to measure the transport and allocation patterns of carbohydrates, nutrients, and phytohormones labeled with positron-emitting radioisotopes. However, the cost of PET and its limitation to smaller plants has restricted its use in plant biology. Here we describe the adaptation and optimization of a commercial clinical PET scannermore » to measure transport dynamics and allocation patterns of 11C-photoassimilates in large crops. Based on measurements of a phantom, we optimized instrument settings, including use of 3-D mode and attenuation correction to maximize the accuracy of measurements. To demonstrate the utility of PET, we measured 11C-photoassimilate transport and allocation in Sorghum bicolor, an important staple crop, at vegetative and reproductive stages (40 and 70 days after planting; DAP). The 11C-photoassimilate transport speed did not change over the two developmental stages. However, within a stem, transport speeds were reduced across nodes, likely due to higher 11C-photoassimilate unloading in the nodes. Photosynthesis in leaves and the amount of 11C that was exported to the rest of the plant decreased as plants matured. In young plants, exported 11C was allocated mostly (88 %) to the roots and stem, but in flowering plants (70 DAP) the majority of the exported 11C (64 %) was allocated to the apex. Our results show that commercial PET scanners can be used reliably to measure whole-plant C-allocation in large plants nondestructively including, importantly, allocation to roots in soil. This capability revealed extreme changes in carbon allocation in sorghum plants, as they advanced to maturity. Further, our results suggest that nodes may be important control points for photoassimilate distribution in crops of the family Poaceae. In conclusion, quantifying real-time carbon allocation and photoassimilate transport dynamics, as demonstrated here, will be important for functional genomic studies to unravel the mechanisms controlling phloem transport in large crop plants, which will provide crucial insights for improving yields.« less

In vivo quantitative imaging of photoassimilate transport dynamics and allocation in large plants using a commercial positron emission tomography (PET) scanner

DOE PAGES

Karve, Abhijit A.; Alexoff, David; Kim, Dohyun; ...

2015-11-09

Although important aspects of whole-plant carbon allocation in crop plants (e.g., to grain) occur late in development when the plants are large, techniques to study carbon transport and allocation processes have not been adapted for large plants. Positron emission tomography (PET), developed for dynamic imaging in medicine, has been applied in plant studies to measure the transport and allocation patterns of carbohydrates, nutrients, and phytohormones labeled with positron-emitting radioisotopes. However, the cost of PET and its limitation to smaller plants has restricted its use in plant biology. Here we describe the adaptation and optimization of a commercial clinical PET scannermore » to measure transport dynamics and allocation patterns of 11C-photoassimilates in large crops. Based on measurements of a phantom, we optimized instrument settings, including use of 3-D mode and attenuation correction to maximize the accuracy of measurements. To demonstrate the utility of PET, we measured 11C-photoassimilate transport and allocation in Sorghum bicolor, an important staple crop, at vegetative and reproductive stages (40 and 70 days after planting; DAP). The 11C-photoassimilate transport speed did not change over the two developmental stages. However, within a stem, transport speeds were reduced across nodes, likely due to higher 11C-photoassimilate unloading in the nodes. Photosynthesis in leaves and the amount of 11C that was exported to the rest of the plant decreased as plants matured. In young plants, exported 11C was allocated mostly (88 %) to the roots and stem, but in flowering plants (70 DAP) the majority of the exported 11C (64 %) was allocated to the apex. Our results show that commercial PET scanners can be used reliably to measure whole-plant C-allocation in large plants nondestructively including, importantly, allocation to roots in soil. This capability revealed extreme changes in carbon allocation in sorghum plants, as they advanced to maturity. Further, our results suggest that nodes may be important control points for photoassimilate distribution in crops of the family Poaceae. In conclusion, quantifying real-time carbon allocation and photoassimilate transport dynamics, as demonstrated here, will be important for functional genomic studies to unravel the mechanisms controlling phloem transport in large crop plants, which will provide crucial insights for improving yields.« less

Optimized in vivo detection of dopamine release using 18F-fallypride PET.

PubMed

Ceccarini, Jenny; Vrieze, Elske; Koole, Michel; Muylle, Tom; Bormans, Guy; Claes, Stephan; Van Laere, Koen

2012-10-01

The high-affinity D(2/3) PET radioligand (18)F-fallypride offers the possibility of measuring both striatal and extrastriatal dopamine release during activation paradigms. When a single (18)F-fallypride scanning protocol is used, task timing is critical to the ability to explore both striatal and extrastriatal dopamine release simultaneously. We evaluated the sensitivity and optimal timing of task administration for a single (18)F-fallypride PET protocol and the linearized simplified reference region kinetic model in detecting both striatal and extrastriatal reward-induced dopamine release, using human and simulation studies. Ten healthy volunteers underwent a single-bolus (18)F-fallypride PET protocol. A reward responsiveness learning task was initiated at 100 min after injection. PET data were analyzed using the linearized simplified reference region model, which accounts for time-dependent changes in (18)F-fallypride displacement. Voxel-based statistical maps, reflecting task-induced D(2/3) ligand displacement, and volume-of-interest-based analysis were performed to localize areas with increased ligand displacement after task initiation, thought to be proportional to changes in endogenous dopamine release (γ parameter). Simulated time-activity curves for baseline and hypothetical dopamine release functions (different peak heights of dopamine and task timings) were generated using the enhanced receptor-binding kinetic model to investigate γ as a function of these parameters. The reward task induced increased ligand displacement in extrastriatal regions of the reward circuit, including the medial orbitofrontal cortex, ventromedial prefrontal cortex, and dorsal anterior cingulate cortex. For task timing of 100 min, ligand displacement was found for the striatum only when peak height of dopamine was greater than 240 nM, whereas for frontal regions, γ was always positive for all task timings and peak heights of dopamine. Simulation results for a peak height of dopamine of 200 nM showed that an effect of striatal ligand displacement could be detected only when task timing was greater than 120 min. The prefrontal and anterior cingulate cortices are involved in reward responsiveness that can be measured using (18)F-fallypride PET in a single scanning session. To measure both striatal and extrastriatal dopamine release, the height of dopamine released and task timing need to be considered in designing activation studies depending on regional D(2/3) density.

A comparative uptake study of multiplexed PET tracers in mice with turpentine-induced inflammation.

PubMed

Huang, Tingting; Wang, Hongliang; Tang, Ganghua; Liang, Xiang; Nie, Dahong; Yi, Chang; Wu, Kening

2012-11-26

The potential value of multiplexed positron emission tomography (PET) tracers in mice with turpentine-induced inflammation was evaluated and compared with 2-[¹⁸F]fluoro-2-deoxy-D-glucose ([¹⁸F]FDG) for glucose metabolism imaging. These PET tracers included [¹⁸F]fluoromethylcholine ([¹⁸F]FCH) for choline metabolism imaging, (S-[¹¹C]methyl)-D-cysteine ([¹¹C]DMCYS) for amino acid metabolism imaging, [¹¹C]bis(zinc(II)-dipicolylamine) ([¹¹C]DPA-Zn²⁺) for apoptosis imaging, 2-(4-N-[¹¹C]-methylaminophenyl)-6-hydroxybenzothiazole ([¹¹C]PIB) for β amyloid binding imaging, and [¹⁸F]fluoride (¹⁸F⁻) for bone metabolism imaging. In mice with turpentine-induced inflammation mice, the biodistribution of all the tracers mentioned above at 5, 15, 30, 45, and 60 min postinjection was determined. Also, the time-course curves of the tracer uptake ratios for inflammatory thigh muscle (IM) to normal uninflammatory thigh muscle (NM), IM to blood (BL), IM to brain (BR), and IM to liver (LI) were acquired, respectively. Moreover, PET imaging with the tracers within 60 min postinjection on a clinical PET/CT scanner was also conducted. [¹⁸F]FDG and ¹⁸F⁻ showed relatively higher uptake ratios for IM to NM, IM to BL, IM to BR, and IM to LI than [¹⁸F]FCH, [¹¹C]DPA-Zn²⁺, [¹¹C]DMCYS and [¹¹C]PIB, which were highly consistent with the results delineated in PET images. The results demonstrate that ¹⁸F⁻ seems to be a potential PET tracer for inflammation imaging. [¹⁸F]FCH and [¹¹C]DMCYS, with lower accumulation in inflammatory tissue than [¹⁸F]FDG, are not good PET tracers for inflammation imaging. As a promising inflammatory tracer, the chemical structure of [¹¹C]DPA-Zn²⁺ needs to be further optimized.

Matching the reaction-diffusion simulation to dynamic [18F]FMISO PET measurements in tumors: extension to a flow-limited oxygen-dependent model.

PubMed

Shi, Kuangyu; Bayer, Christine; Gaertner, Florian C; Astner, Sabrina T; Wilkens, Jan J; Nüsslin, Fridtjof; Vaupel, Peter; Ziegler, Sibylle I

2017-02-01

Positron-emission tomography (PET) with hypoxia specific tracers provides a noninvasive method to assess the tumor oxygenation status. Reaction-diffusion models have advantages in revealing the quantitative relation between in vivo imaging and the tumor microenvironment. However, there is no quantitative comparison of the simulation results with the real PET measurements yet. The lack of experimental support hampers further applications of computational simulation models. This study aims to compare the simulation results with a preclinical [ 18 F]FMISO PET study and to optimize the reaction-diffusion model accordingly. Nude mice with xenografted human squamous cell carcinomas (CAL33) were investigated with a 2 h dynamic [ 18 F]FMISO PET followed by immunofluorescence staining using the hypoxia marker pimonidazole and the endothelium marker CD 31. A large data pool of tumor time-activity curves (TAC) was simulated for each mouse by feeding the arterial input function (AIF) extracted from experiments into the model with different configurations of the tumor microenvironment. A measured TAC was considered to match a simulated TAC when the difference metric was below a certain, noise-dependent threshold. As an extension to the well-established Kelly model, a flow-limited oxygen-dependent (FLOD) model was developed to improve the matching between measurements and simulations. The matching rate between the simulated TACs of the Kelly model and the mouse PET data ranged from 0 to 28.1% (on average 9.8%). By modifying the Kelly model to an FLOD model, the matching rate between the simulation and the PET measurements could be improved to 41.2-84.8% (on average 64.4%). Using a simulation data pool and a matching strategy, we were able to compare the simulated temporal course of dynamic PET with in vivo measurements. By modifying the Kelly model to a FLOD model, the computational simulation was able to approach the dynamic [ 18 F]FMISO measurements in the investigated tumors.

In vivo PET/CT in a human glioblastoma chicken chorioallantoic membrane model: a new tool for oncology and radiotracer development.

PubMed

Warnock, Geoff; Turtoi, Andrei; Blomme, Arnaud; Bretin, Florian; Bahri, Mohamed Ali; Lemaire, Christian; Libert, Lionel Cyrille; Seret, Alain E J J; Luxen, André; Castronovo, Vincenzo; Plenevaux, Alain R E G

2013-10-01

For many years the laboratory mouse has been used as the standard model for in vivo oncology research, particularly in the development of novel PET tracers, but the growth of tumors on chicken chorioallantoic membrane (CAM) provides a more rapid, low cost, and ethically sustainable alternative. For the first time, to our knowledge, we demonstrate the feasibility of in vivo PET and CT imaging in a U87 glioblastoma tumor model on chicken CAM, with the aim of applying this model for screening of novel PET tracers. U87 glioblastoma cells were implanted on the CAM at day 11 after fertilization and imaged at day 18. A small-animal imaging cell was used to maintain incubation and allow anesthesia using isoflurane. Radiotracers were injected directly into the exposed CAM vasculature. Sodium (18)F-fluoride was used to validate the imaging protocol, demonstrating that image-degrading motion can be removed with anesthesia. Tumor glucose metabolism was imaged using (18)F-FDG, and tumor protein synthesis was imaged using 2-(18)F-fluoro-l-tyrosine. Anatomic images were obtained by contrast-enhanced CT, facilitating clear delineation of the tumor, delineation of tracer uptake in tumor versus embryo, and accurate volume measurements. PET imaging of tumor glucose metabolism and protein synthesis was successfully demonstrated in the CAM U87 glioblastoma model. Catheterization of CAM blood vessels facilitated dynamic imaging of glucose metabolism with (18)F-FDG and demonstrated the ability to study PET tracer uptake over time in individual tumors, and CT imaging improved the accuracy of tumor volume measurements. We describe the novel application of PET/CT in the CAM tumor model, with optimization of typical imaging protocols. PET imaging in this valuable tumor model could prove particularly useful for rapid, high-throughput screening of novel radiotracers.

A novel dual gating approach using joint inertial sensors: implications for cardiac PET imaging

NASA Astrophysics Data System (ADS)

Jafari Tadi, Mojtaba; Teuho, Jarmo; Lehtonen, Eero; Saraste, Antti; Pänkäälä, Mikko; Koivisto, Tero; Teräs, Mika

2017-10-01

Positron emission tomography (PET) is a non-invasive imaging technique which may be considered as the state of art for the examination of cardiac inflammation due to atherosclerosis. A fundamental limitation of PET is that cardiac and respiratory motions reduce the quality of the achieved images. Current approaches for motion compensation involve gating the PET data based on the timing of quiescent periods of cardiac and respiratory cycles. In this study, we present a novel gating method called microelectromechanical (MEMS) dual gating which relies on joint non-electrical sensors, i.e. tri-axial accelerometer and gyroscope. This approach can be used for optimized selection of quiescent phases of cardiac and respiratory cycles. Cardiomechanical activity according to echocardiography observations was investigated to confirm whether this dual sensor solution can provide accurate trigger timings for cardiac gating. Additionally, longitudinal chest motions originating from breathing were measured by accelerometric- and gyroscopic-derived respiratory (ADR and GDR) tracking. The ADR and GDR signals were evaluated against Varian real-time position management (RPM) signals in terms of amplitude and phase. Accordingly, high linear correlation and agreement were achieved between the reference electrocardiography, RPM, and measured MEMS signals. We also performed a Ge-68 phantom study to evaluate possible metal artifacts caused by the integrated read-out electronics including mechanical sensors and semiconductors. The reconstructed phantom images did not reveal any image artifacts. Thus, it was concluded that MEMS-driven dual gating can be used in PET studies without an effect on the quantitative or visual accuracy of the PET images. Finally, the applicability of MEMS dual gating for cardiac PET imaging was investigated with two atherosclerosis patients. Dual gated PET images were successfully reconstructed using only MEMS signals and both qualitative and quantitative assessments revealed encouraging results that warrant further investigation of this method.

Quantifying the robustness of [18F]FDG-PET/CT radiomic features with respect to tumor delineation in head and neck and pancreatic cancer patients.

PubMed

Belli, Maria Luisa; Mori, Martina; Broggi, Sara; Cattaneo, Giovanni Mauro; Bettinardi, Valentino; Dell'Oca, Italo; Fallanca, Federico; Passoni, Paolo; Vanoli, Emilia Giovanna; Calandrino, Riccardo; Di Muzio, Nadia; Picchio, Maria; Fiorino, Claudio

2018-05-01

To investigate the robustness of PET radiomic features (RF) against tumour delineation uncertainty in two clinically relevant situations. Twenty-five head-and-neck (HN) and 25 pancreatic cancer patients previously treated with 18 F-Fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT)-based planning optimization were considered. Seven FDG-based contours were delineated for tumour (T) and positive lymph nodes (N, for HN patients only) following manual (2 observers), semi-automatic (based on SUV maximum gradient: PET_Edge) and automatic (40%, 50%, 60%, 70% SUV_max thresholds) methods. Seventy-three RF (14 of first order and 59 of higher order) were extracted using the CGITA software (v.1.4). The impact of delineation on volume agreement and RF was assessed by DICE and Intra-class Correlation Coefficients (ICC). A large disagreement between manual and SUV_max method was found for thresholds  ≥50%. Inter-observer variability showed median DICE values between 0.81 (HN-T) and 0.73 (pancreas). Volumes defined by PET_Edge were better consistent with the manual ones compared to SUV40%. Regarding RF, 19%/19%/47% of the features showed ICC < 0.80 between observers for HN-N/HN-T/pancreas, mostly in the Voxel-alignment matrix and in the intensity-size zone matrix families. RFs with ICC < 0.80 against manual delineation (taking the worst value) increased to 44%/36%/61% for PET_Edge and to 69%/53%/75% for SUV40%. About 80%/50% of 72 RF were consistent between observers for HN/pancreas patients. PET_edge was sufficiently robust against manual delineation while SUV40% showed a worse performance. This result suggests the possibility to replace manual with semi-automatic delineation of HN and pancreas tumours in studies including PET radiomic analyses. Copyright © 2018 Associazione Italiana di Fisica Medica. Published by Elsevier Ltd. All rights reserved.

(18)F-FDG PET/CT, cytoreductive surgery and intraperitoneal chemohyperthermia for the therapeutic management in peritoneal carcinomatosis: A pilot study.

PubMed

Cistaro, A; Cucinotta, M; Cassalia, L; Priola, A; Priola, S; Pappalardo, M; Coppolino, P; De Simone, M; Quartuccio, N

2016-01-01

Peritoneal carcinomatosis is a common evolution of neoplasms and the terminal stage of disease. A new therapeutic technique, based on the total surgical removal of peritoneal lesions (peritonectomy procedure - PP) combined with the intraperitoneal chemohyperthermia (IPCH), has been developed. Proper patient selection is mandatory for optimizing the results of treatment. The aim of this study was to investigate the role of [(18)F]fluoro-2-deoxy-d-glucose Positron Emission Tomography/Computed Tomography ((18)F-FDG PET/CT) in patients with peritoneal carcinosis selected to undergo PP and IPCH. Furthermore, we aimed to identify characteristic patterns of abdominal(18)F-FDG uptake and to correlate these patterns with available anatomic findings after surgery. Patients with either histologically confirmed peritoneal carcinosis or suspected upon clinical follow-up and/or imaging findings were prospectively submitted to pre-surgery (18)F-FDG PET/CT scan. Only those patients without evidence of extra-peritoneal metastases at PET/CT scan were treated with PP and IPCH. 11 patients with peritoneal carcinomatosis (5 colorectal, 4 ovarian, 1 pancreatic) and 1 unknown primitive cancer, were eligible for the study. In all cases PET/CT scan showed multiple peritoneal implants. In 6 out of 11 cases (54%) metastases were evidenced by (18)F-FDG PET/CT: 2 cases with liver metastases; 1 case with bone metastases; 3 patients with lymph-node lesions. Two distinct imaging patterns, with focal or diffuse increased (18)F-FDG uptake, were recognized. PP+IPCH of patients selected by (18)F-FDG PET/CT seems to be safe and feasible. PET/CT scan appears as a reliable tool for the detection, characterization of peritoneal implants with potential impact in the therapeutic management of these patients. Copyright © 2016 Elsevier España, S.L.U. and SEMNIM. All rights reserved.

Relationships between serum PSA levels, Gleason scores and results of 68Ga-PSMAPET/CT in patients with recurrent prostate cancer.

PubMed

Sanli, Yasemin; Kuyumcu, Serkan; Sanli, Oner; Buyukkaya, Fikret; İribaş, Ayça; Alcin, Goksel; Darendeliler, Emin; Ozluk, Yasemin; Yildiz, Sevda Ozel; Turkmen, Cüneyt

2017-11-01

To investigate the relationship between serum PSA level, Gleason score of PCa and the outcomes of Ga 68 -PSMA PET/CT in patients with recurrent PCa. A total of 109 consecutive patients (median age 71 years; range 48-89 years) who had PSA recurrence after RP and/or hormonotherapy and/or radiotherapy were included in this study. Local recurrences, lymph node metastasis (pelvic, abdominal and/or supradiaphragmatic), bone metastases (oligometastatic/multimetastatic) and other metastatic sites (lung, liver, brain, etc) were documented. In 91(83.4%) patients at least one lesion characteristic for PCa was detected by 68 Ga-PSMA PET/CT. The median serum total PSA (tPSA) was 6.5 (0.2-640) ng/ml.There was a significant difference between 68 Ga-PSMA PET/CT positive and negative patients in terms of serum total PSA value. No statistical significance was found between positive and negative 68 Ga-PSMA PET/CT findings in terms of Gleason score. Local recurrence was detected in 56 patients. whereas lymph node metastases were demonstrated in 46 patients. Pelvic nodal disease was the most frequent presentation followed by abdominal and supradiaphragmaticnodal involvement. Bone metastases [oligometastasis, (n = 20); multimetastasis, (n = 35)⦌ were also detected in 55 patients. In the ROC analysis for the study cohort, the optimal cut-off value of total serum PSA was determined as 0.67 ng/ml for distinguishing between positive and negative 68 Ga-PSMA PET/CT images, with an area under curve of 0.952 (95% CI 0.911-0.993). 68 Ga-PSMA PET/CT was found to be an effective tool for the detection of recurrent PCa. Even though no relationship was detected between the GS and 68 Ga-PSMA PET/CT findings, serum total PSA values may be used for estimating the likelihood of positive 68 Ga-PSMA PET/CT results.

Optical fringe-reflection deflectometry with bundle adjustment

NASA Astrophysics Data System (ADS)

Xiao, Yong-Liang; Li, Sikun; Zhang, Qican; Zhong, Jianxin; Su, Xianyu; You, Zhisheng

2018-06-01

Liquid crystal display (LCD) screens are located outside of a camera's field of view in fringe-reflection deflectometry. Therefore, fringes that are displayed on LCD screens are obtained through specular reflection by a fixed camera. Thus, the pose calibration between the camera and LCD screen is one of the main challenges in fringe-reflection deflectometry. A markerless planar mirror is used to reflect the LCD screen more than three times, and the fringes are mapped into the fixed camera. The geometrical calibration can be accomplished by estimating the pose between the camera and the virtual image of fringes. Considering the relation between their pose, the incidence and reflection rays can be unified in the camera frame, and a forward triangulation intersection can be operated in the camera frame to measure three-dimensional (3D) coordinates of the specular surface. In the final optimization, constraint-bundle adjustment is operated to refine simultaneously the camera intrinsic parameters, including distortion coefficients, estimated geometrical pose between the LCD screen and camera, and 3D coordinates of the specular surface, with the help of the absolute phase collinear constraint. Simulation and experiment results demonstrate that the pose calibration with planar mirror reflection is simple and feasible, and the constraint-bundle adjustment can enhance the 3D coordinate measurement accuracy in fringe-reflection deflectometry.

Ultrasound, elastography, and fluorodeoxyglucose positron emission tomography/computed tomography imaging in Riedel's thyroiditis: report of two cases.

PubMed

Slman, Rouba; Monpeyssen, Hervé; Desarnaud, Serge; Haroche, Julien; Fediaevsky, Laurence Du Pasquier; Fabrice, Menegaux; Seret-Begue, Dominique; Amoura, Zahir; Aurengo, André; Leenhardt, Laurence

2011-07-01

Riedel's thyroiditis (RT) is a rare disease characterized by a chronic inflammatory lesion of the thyroid gland with invasion by a dense fibrosis. Publications of the imaging features of RT are scarce. To our knowledge, ultrasound elastography (USE) findings have not been previously reported. Therefore, we describe two patients with RT who were imaged with ultrasonography (US), USE, and fluorodeoxyglucose positron emission tomography/computed tomography (FDG-PET/CT). Two women were referred for a large, hard goiter with compressive symptoms (dyspnea and dysphagia); in one patient, the goiter was associated with retroperitoneal fibrosis. In both cases, RT was confirmed by surgical biopsy with pathological examination. Thyroid US imaging was performed with a US scan and a 10-13 MHz linear transducer. The hardness of the tissues was analyzed using transient USE (ShearWave, Aixplorer-SuperSonic Imagine). PET/CT scanning was performed with a Philips Gemini GXL camera (GE Medical Systems). In the first patient, US examination revealed a compressive multinodular goiter with large solid hypoechoic and poorly vascularized areas adjacent to the nodules. The predominant right nodule was hypoechoic with irregular margins. The second patient had a hypoechoic goiter with large bilateral hypoechoic areas. In both cases, an unusual feature was observed: the presence of tissue surrounding the primitive carotid artery, associated with thrombi of the internal jugular vein. Further, USE showed heterogeneity in the stiffness values of the thyroid parenchyma varying between 21 kPa and 281 kPa. FDG-PET/CT imaging showed uptake foci in the thyroid gland. In both cases, US showed a decrease in the thyroid gland volume and the disappearance of encasement of the neck vasculature in response to corticosteroid treatment. In contrast, the FDG-PET/CT features remained unchanged. US features, such as vascular encasement and improvement under corticosteroid treatment, seem to be specific to this rare disease. For the first time, USE documents the hardness of RT tissues. Apart from the FDG-PET/CT findings that merit further investigation, US and USE prove useful tools in the assessment of such a rare disease.

Physical and engineering aspect of carbon beam therapy

NASA Astrophysics Data System (ADS)

Kanai, Tatsuaki; Kanematsu, Nobuyuki; Minohara, Shinichi; Yusa, Ken; Urakabe, Eriko; Mizuno, Hideyuki; Iseki, Yasushi; Kanazawa, Mitsutaka; Kitagawa, Atsushi; Tomitani, Takehiro

2003-08-01

Conformal irradiation system of HIMAC has been up-graded for a clinical trial using a technique of a layer-stacking method. The system has been developed for localizing irradiation dose to target volume more effectively than the present irradiation dose. With dynamic control of the beam modifying devices, a pair of wobbler magnets, and multileaf collimator and range shifter, during the irradiation, more conformal radiotherapy can be achieved. The system, which has to be adequately safe for patient irradiations, was constructed and tested from a viewpoint of safety and the quality of the dose localization realized. A secondary beam line has been constructed for use of radioactive beam in heavy-ion radiotherapy. Spot scanning method has been adapted for the beam delivery system of the radioactive beam. Dose distributions of the spot beam were measured and analyzed taking into account of aberration of the beam optics. Distributions of the stopped positron-emitter beam can be observed by PET. Pencil beam of the positron-emitter, about 1 mm size, can also be used for measurements ranges of the test beam in patients using positron camera. The positron camera, consisting of a pair of Anger-type scintillation detectors, has been developed for this verification before treatment. Wash-out effect of the positron-emitter was examined using the positron camera installed. In this report, present status of the HIMAC irradiation system is described in detail.