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Sample records for mri scanner environments

  1. The impact of MRI scanner environment on perceptual decision-making.

    PubMed

    van Maanen, Leendert; Forstmann, Birte U; Keuken, Max C; Wagenmakers, Eric-Jan; Heathcote, Andrew

    2016-03-01

    Despite the widespread use of functional magnetic resonance imaging (fMRI), few studies have addressed scanner effects on performance. The studies that have examined this question show a wide variety of results. In this article we report analyses of three experiments in which participants performed a perceptual decision-making task both in a traditional setting as well as inside an MRI scanner. The results consistently show that response times increase inside the scanner. Error rates also increase, but to a lesser extent. To reveal the underlying mechanisms that drive the behavioral changes when performing a task inside the MRI scanner, the data were analyzed using the linear ballistic accumulator model of decision-making. These analyses show that, in the scanner, participants exhibit a slow down of the motor component of the response and have less attentional focus on the task. However, the balance between focus and motor slowing depends on the specific task requirements.

  2. Visceral pain perception in patients with irritable bowel syndrome and healthy volunteers is affected by the MRI scanner environment

    PubMed Central

    Wong, Reuben K; Van Oudenhove, Lukas; Li, Xinhua; Cao, Yang; Ho, Khek Yu

    2015-01-01

    Background The MRI scanner environment induces marked psychological effects, but specific effects on pain perception and processing are unknown and relevant to all brain imaging studies. Objectives and methods We performed visceral and somatic quantitative sensory and pain testing and studied endogenous pain modulation by heterotopic stimulation outside and inside the functional MRI scanner in 11 healthy controls and 13 patients with irritable bowel syndrome. Results Rectal pain intensity (VAS 0–100) during identical distension pressures increased from 39 (95% confidence interval: 35–42) outside the scanner to 53 (43–63) inside the scanner in irritable bowel syndrome, and from 42 (31–52) to 49 (39–58), respectively, in controls (ANOVA for scanner effect: p = 0.006, group effect: p = 0.92). The difference in rectal pain outside versus inside correlated significantly with stress (r = −0.76, p = 0.006), anxiety (r = −0.68, p = 0.02) and depression scores (r = −0.67, p = 0.02) in controls, but not in irritable bowel syndrome patients, who a priori had significantly higher stress and anxiety scores. ANOVA analysis showed trends for effect of the scanner environment and subject group on endogenous pain modulation (p = 0.09 and p = 0.1, respectively), but not on somatic pain (p > 0.3). Conclusion The scanner environment significantly increased visceral, but not somatic, pain perception in irritable bowel syndrome patients and healthy controls in a protocol specifically aimed at investigating visceral pain. Psychological factors, including anxiety and stress, are the likely underlying causes, whereas classic endogenous pain modulation pathways activated by heterotopic stimulation play a lesser role. These results are highly relevant to a wide range of imaging applications and need to be taken into account in future pain research. Further controlled studies are indicated to clarify these findings. PMID:26966533

  3. Open magnetic resonance imaging (MRI) scanners.

    PubMed

    Hailey, D

    2006-11-01

    (1) In most MRI scanners, the patient examination table fits inside a long cylindrical tube. Large patients cannot be accommodated, and some persons experience claustrophobic reactions. Open MRI systems, in which the patient is placed between two plates, overcome these disadvantages. (2) Open MRI scanners are widely used in health care. High-field closed MRI systems are preferred for many examinations. (3) Early versions of open MRI scanners had low magnetic field strength, gave poorer image quality than most closed systems, and required longer examination times. Newer open scanners include machines with higher magnetic field strengths and improved image quality. (4) Closed high magnetic field scanners with short magnets and wide bore tubes offer improved comfort to patients, and may be an alternative to open scanners. (5) There is interest in using open systems for intra-operative and image-guided interventions.

  4. Combined PET/MRI scanner

    DOEpatents

    Schlyer, David; Woody, Craig L.; Rooney, William; Vaska, Paul; Stoll, Sean; Pratte, Jean-Francois; O'Connor, Paul

    2007-10-23

    A combined PET/MRI scanner generally includes a magnet for producing a magnetic field suitable for magnetic resonance imaging, a radiofrequency (RF) coil disposed within the magnetic field produced by the magnet and a ring tomograph disposed within the magnetic field produced by the magnet. The ring tomograph includes a scintillator layer for outputting at least one photon in response to an annihilation event, a detection array coupled to the scintillator layer for detecting the at least one photon outputted by the scintillator layer and for outputting a detection signal in response to the detected photon and a front-end electronic array coupled to the detection array for receiving the detection signal, wherein the front-end array has a preamplifier and a shaper network for conditioning the detection signal.

  5. Quest for an open MRI scanner.

    PubMed

    Bertora, Franco; Borceto, Alice; Viale, Andrea; Sandini, Giulio

    2014-01-01

    A study of the motor cortex during the programming, execution and mental representation of voluntary movement is of great relevance; its evaluation in conditions close to reality is necessary, given the close integration of the visuomotor, sensory feedback and proprioceptive systems, as of yet, a functional Magnetic Resonance Imaging (fMRI) scanner allowing a human subject to maintain erect stance, observe the surroundings and conserve limb freedom is still a dream. The need for high field suggests a solenoid magnet geometry that forces an unnatural posture that affects the results, particularly when the motor cortex is investigated. In contrast in a motor functional study, the scanner should allow the subject to sit or stand, with unobstructed sight and unimpeded movement. Two approaches are presented here to solve this problem. In the first approach, an increased field intensity in an open magnet is obtained lining the "back wall" of the cavity with a sheet of current: this boosts the field intensity at the cost of the introduction of a gradient, which has to be canceled by the introduction of an opposite gradient; The second approach is an adaptation of the "double doughnut" architecture, in which the cavity widens at the center to provide additional room for the subject. The detailed design of this kind of structure has proven the feasibility of the solution.

  6. An RF dosimeter for independent SAR measurement in MRI scanners

    SciTech Connect

    Qian, Di; Bottomley, Paul A.; El-Sharkawy, AbdEl-Monem M.; Edelstein, William A.

    2013-12-15

    Purpose: The monitoring and management of radio frequency (RF) exposure is critical for ensuring magnetic resonance imaging (MRI) safety. Commercial MRI scanners can overestimate specific absorption rates (SAR) and improperly restrict clinical MRI scans or the application of new MRI sequences, while underestimation of SAR can lead to tissue heating and thermal injury. Accurate scanner-independent RF dosimetry is essential for measuring actual exposure when SAR is critical for ensuring regulatory compliance and MRI safety, for establishing RF exposure while evaluating interventional leads and devices, and for routine MRI quality assessment by medical physicists. However, at present there are no scanner-independent SAR dosimeters. Methods: An SAR dosimeter with an RF transducer comprises two orthogonal, rectangular copper loops and a spherical MRI phantom. The transducer is placed in the magnet bore and calibrated to approximate the resistive loading of the scanner's whole-body birdcage RF coil for human subjects in Philips, GE and Siemens 3 tesla (3T) MRI scanners. The transducer loop reactances are adjusted to minimize interference with the transmit RF field (B{sub 1}) at the MRI frequency. Power from the RF transducer is sampled with a high dynamic range power monitor and recorded on a computer. The deposited power is calibrated and tested on eight different MRI scanners. Whole-body absorbed power vs weight and body mass index (BMI) is measured directly on 26 subjects. Results: A single linear calibration curve sufficed for RF dosimetry at 127.8 MHz on three different Philips and three GE 3T MRI scanners. An RF dosimeter operating at 123.2 MHz on two Siemens 3T scanners required a separate transducer and a slightly different calibration curve. Measurement accuracy was ∼3%. With the torso landmarked at the xiphoid, human adult whole‑body absorbed power varied approximately linearly with patient weight and BMI. This indicates that whole-body torso SAR is on

  7. An RF dosimeter for independent SAR measurement in MRI scanners

    PubMed Central

    Qian, Di; El-Sharkawy, AbdEl-Monem M.; Bottomley, Paul A.; Edelstein, William A.

    2013-01-01

    Purpose: The monitoring and management of radio frequency (RF) exposure is critical for ensuring magnetic resonance imaging (MRI) safety. Commercial MRI scanners can overestimate specific absorption rates (SAR) and improperly restrict clinical MRI scans or the application of new MRI sequences, while underestimation of SAR can lead to tissue heating and thermal injury. Accurate scanner-independent RF dosimetry is essential for measuring actual exposure when SAR is critical for ensuring regulatory compliance and MRI safety, for establishing RF exposure while evaluating interventional leads and devices, and for routine MRI quality assessment by medical physicists. However, at present there are no scanner-independent SAR dosimeters. Methods: An SAR dosimeter with an RF transducer comprises two orthogonal, rectangular copper loops and a spherical MRI phantom. The transducer is placed in the magnet bore and calibrated to approximate the resistive loading of the scanner's whole-body birdcage RF coil for human subjects in Philips, GE and Siemens 3 tesla (3T) MRI scanners. The transducer loop reactances are adjusted to minimize interference with the transmit RF field (B1) at the MRI frequency. Power from the RF transducer is sampled with a high dynamic range power monitor and recorded on a computer. The deposited power is calibrated and tested on eight different MRI scanners. Whole-body absorbed power vs weight and body mass index (BMI) is measured directly on 26 subjects. Results: A single linear calibration curve sufficed for RF dosimetry at 127.8 MHz on three different Philips and three GE 3T MRI scanners. An RF dosimeter operating at 123.2 MHz on two Siemens 3T scanners required a separate transducer and a slightly different calibration curve. Measurement accuracy was ∼3%. With the torso landmarked at the xiphoid, human adult whole‑body absorbed power varied approximately linearly with patient weight and BMI. This indicates that whole-body torso SAR is on average

  8. An RF dosimeter for independent SAR measurement in MRI scanners

    SciTech Connect

    Qian, Di; Bottomley, Paul A.; El-Sharkawy, AbdEl-Monem M.; Edelstein, William A.

    2013-12-15

    Purpose: The monitoring and management of radio frequency (RF) exposure is critical for ensuring magnetic resonance imaging (MRI) safety. Commercial MRI scanners can overestimate specific absorption rates (SAR) and improperly restrict clinical MRI scans or the application of new MRI sequences, while underestimation of SAR can lead to tissue heating and thermal injury. Accurate scanner-independent RF dosimetry is essential for measuring actual exposure when SAR is critical for ensuring regulatory compliance and MRI safety, for establishing RF exposure while evaluating interventional leads and devices, and for routine MRI quality assessment by medical physicists. However, at present there are no scanner-independent SAR dosimeters. Methods: An SAR dosimeter with an RF transducer comprises two orthogonal, rectangular copper loops and a spherical MRI phantom. The transducer is placed in the magnet bore and calibrated to approximate the resistive loading of the scanner's whole-body birdcage RF coil for human subjects in Philips, GE and Siemens 3 tesla (3T) MRI scanners. The transducer loop reactances are adjusted to minimize interference with the transmit RF field (B{sub 1}) at the MRI frequency. Power from the RF transducer is sampled with a high dynamic range power monitor and recorded on a computer. The deposited power is calibrated and tested on eight different MRI scanners. Whole-body absorbed power vs weight and body mass index (BMI) is measured directly on 26 subjects. Results: A single linear calibration curve sufficed for RF dosimetry at 127.8 MHz on three different Philips and three GE 3T MRI scanners. An RF dosimeter operating at 123.2 MHz on two Siemens 3T scanners required a separate transducer and a slightly different calibration curve. Measurement accuracy was ∼3%. With the torso landmarked at the xiphoid, human adult whole‑body absorbed power varied approximately linearly with patient weight and BMI. This indicates that whole-body torso SAR is on

  9. An RF dosimeter for independent SAR measurement in MRI scanners.

    PubMed

    Qian, Di; El-Sharkawy, Abdel-Monem M; Bottomley, Paul A; Edelstein, William A

    2013-12-01

    The monitoring and management of radio frequency (RF) exposure is critical for ensuring magnetic resonance imaging (MRI) safety. Commercial MRI scanners can overestimate specific absorption rates (SAR) and improperly restrict clinical MRI scans or the application of new MRI sequences, while underestimation of SAR can lead to tissue heating and thermal injury. Accurate scanner-independent RF dosimetry is essential for measuring actual exposure when SAR is critical for ensuring regulatory compliance and MRI safety, for establishing RF exposure while evaluating interventional leads and devices, and for routine MRI quality assessment by medical physicists. However, at present there are no scanner-independent SAR dosimeters. An SAR dosimeter with an RF transducer comprises two orthogonal, rectangular copper loops and a spherical MRI phantom. The transducer is placed in the magnet bore and calibrated to approximate the resistive loading of the scanner's whole-body birdcage RF coil for human subjects in Philips, GE and Siemens 3 tesla (3T) MRI scanners. The transducer loop reactances are adjusted to minimize interference with the transmit RF field (B1) at the MRI frequency. Power from the RF transducer is sampled with a high dynamic range power monitor and recorded on a computer. The deposited power is calibrated and tested on eight different MRI scanners. Whole-body absorbed power vs weight and body mass index (BMI) is measured directly on 26 subjects. A single linear calibration curve sufficed for RF dosimetry at 127.8 MHz on three different Philips and three GE 3T MRI scanners. An RF dosimeter operating at 123.2 MHz on two Siemens 3T scanners required a separate transducer and a slightly different calibration curve. Measurement accuracy was ∼3%. With the torso landmarked at the xiphoid, human adult whole-body absorbed power varied approximately linearly with patient weight and BMI. This indicates that whole-body torso SAR is on average independent of the imaging

  10. Speech Perception in MRI Scanner Noise by Persons with Aphasia

    ERIC Educational Resources Information Center

    Healy, Eric W.; Moser, Dana C.; Morrow-Odom, K. Leigh; Hall, Deborah A.; Fridriksson, Julius

    2007-01-01

    Purpose: To examine reductions in performance on auditory tasks by aphasic and neurologically intact individuals as a result of concomitant magnetic resonance imaging (MRI) scanner noise. Method: Four tasks together forming a continuum of linguistic complexity were developed. They included complex-tone pitch discrimination, same-different…

  11. Speech Perception in MRI Scanner Noise by Persons with Aphasia

    ERIC Educational Resources Information Center

    Healy, Eric W.; Moser, Dana C.; Morrow-Odom, K. Leigh; Hall, Deborah A.; Fridriksson, Julius

    2007-01-01

    Purpose: To examine reductions in performance on auditory tasks by aphasic and neurologically intact individuals as a result of concomitant magnetic resonance imaging (MRI) scanner noise. Method: Four tasks together forming a continuum of linguistic complexity were developed. They included complex-tone pitch discrimination, same-different…

  12. Acoustic noise reduction in a 4 T MRI scanner.

    PubMed

    Mechefske, Chris K; Geris, Ryan; Gati, Joseph S; Rutt, Brian K

    2002-01-01

    High-field, high-speed magnetic resonance imaging (MRI) can generate high levels of noise. There is ongoing concern in the medical and imaging research communities regarding the detrimental effects of high acoustic levels on auditory function, patient anxiety, verbal communication between patients and health care workers and ultimately MR image quality. In order to effectively suppress the noise levels inside MRI scanners, the sound field needs to be accurately measured and characterized. This paper presents the results of measurements of the sound radiation from a gradient coil cylinder within a 4 T MRI scanner under a variety of conditions. These measurement results show: (1) that noise levels can be significantly reduced through the use of an appropriately designed passive acoustic liner; and (2) the true noise levels that are experienced by patients during echo planar imaging.

  13. Robotic Prostate Biopsy in Closed MRI Scanner

    DTIC Science & Technology

    2009-02-01

    robots, and biologically inspired robots. Csaba Csoma received the B.Sc. degree in computer science from Dennis Gabor University, Budapest, Hungary...Nobuhiko Hata, Member, IEEE, and Gabor Fichtinger, Member, IEEE Abstract—Magnetic resonance imaging (MRI) can provide high- quality 3-D visualization of...Simon.DiMaio@intusurg.com). G. Fichtinger is with the School of Computing, Queen’s University, Kingston, ON K7L 3N6, Canada (e-mail: gabor

  14. Robotic Prostate Biopsy in Closed MRI Scanner

    DTIC Science & Technology

    2008-02-01

    MR images were used to plan and monitor transperineal needle placement. The needles were inserted manually using a guide comprising a grid of holes...and manually manipulated mechanical linkage to aim a needle guide for transrectal prostate biopsy with MRI guidance [18]. With the use of three...is situated upon a manual linear slide that positions the robot in the access tunnel and allows fast removal for reloading brachyther- apy needles or

  15. Visual stimulus presentation using fiber optics in the MRI scanner.

    PubMed

    Huang, Ruey-Song; Sereno, Martin I

    2008-03-30

    Imaging the neural basis of visuomotor actions using fMRI is a topic of increasing interest in the field of cognitive neuroscience. One challenge is to present realistic three-dimensional (3-D) stimuli in the subject's peripersonal space inside the MRI scanner. The stimulus generating apparatus must be compatible with strong magnetic fields and must not interfere with image acquisition. Virtual 3-D stimuli can be generated with a stereo image pair projected onto screens or via binocular goggles. Here, we describe designs and implementations for automatically presenting physical 3-D stimuli (point-light targets) in peripersonal and near-face space using fiber optics in the MRI scanner. The feasibility of fiber-optic based displays was demonstrated in two experiments. The first presented a point-light array along a slanted surface near the body, and the second presented multiple point-light targets around the face. Stimuli were presented using phase-encoded paradigms in both experiments. The results suggest that fiber-optic based displays can be a complementary approach for visual stimulus presentation in the MRI scanner.

  16. Acute vertigo in an anesthesia provider during exposure to a 3T MRI scanner.

    PubMed

    Gorlin, Andrew; Hoxworth, Joseph M; Pavlicek, William; Thunberg, Christopher A; Seamans, David

    2015-01-01

    Vertigo induced by exposure to the magnetic field of a magnetic resonance imaging (MRI) scanner is a well-known phenomenon within the radiology community but is not widely appreciated by other clinical specialists. Here, we describe a case of an anesthetist experiencing acute vertigo while providing sedation to a patient undergoing a 3 Tesla MRI scan. After discussing previous reports, and the evidence surrounding MRI-induced vertigo, we review potential etiologies that include the effects of both static and time-varying magnetic fields on the vestibular apparatus. We conclude our review by discussing the occupational standards that exist for MRI exposure and methods to minimize the risks of MRI-induced vertigo for clinicians working in the MRI environment.

  17. fMRI Scanner Noise Interaction with Affective Neural Processes

    PubMed Central

    Skouras, Stavros; Gray, Marcus; Critchley, Hugo; Koelsch, Stefan

    2013-01-01

    The purpose of the present study was the investigation of interaction effects between functional MRI scanner noise and affective neural processes. Stimuli comprised of psychoacoustically balanced musical pieces, expressing three different emotions (fear, neutral, joy). Participants (N=34, 19 female) were split into two groups, one subjected to continuous scanning and another subjected to sparse temporal scanning that features decreased scanner noise. Tests for interaction effects between scanning group (sparse/quieter vs continuous/noisier) and emotion (fear, neutral, joy) were performed. Results revealed interactions between the affective expression of stimuli and scanning group localized in bilateral auditory cortex, insula and visual cortex (calcarine sulcus). Post-hoc comparisons revealed that during sparse scanning, but not during continuous scanning, BOLD signals were significantly stronger for joy than for fear, as well as stronger for fear than for neutral in bilateral auditory cortex. During continuous scanning, but not during sparse scanning, BOLD signals were significantly stronger for joy than for neutral in the left auditory cortex and for joy than for fear in the calcarine sulcus. To the authors' knowledge, this is the first study to show a statistical interaction effect between scanner noise and affective processes and extends evidence suggesting scanner noise to be an important factor in functional MRI research that can affect and distort affective brain processes. PMID:24260420

  18. Absolute Temperature Monitoring Using RF Radiometry in the MRI Scanner

    PubMed Central

    El-Sharkawy, AbdEl-Monem M.; Sotiriadis, Paul P.; Bottomley, Paul A.; Atalar, Ergin

    2007-01-01

    Temperature detection using microwave radiometry has proven value for noninvasively measuring the absolute temperature of tissues inside the body. However, current clinical radiometers operate in the gigahertz range, which limits their depth of penetration. We have designed and built a noninvasive radiometer which operates at radio frequencies (64 MHz) with ∼100-kHz bandwidth, using an external RF loop coil as a thermal detector. The core of the radiometer is an accurate impedance measurement and automatic matching circuit of 0.05 Ω accuracy to compensate for any load variations. The radiometer permits temperature measurements with accuracy of ±0.1°K, over a tested physiological range of 28° C–40° C in saline phantoms whose electric properties match those of tissue. Because 1.5 T magnetic resonance imaging (MRI) scanners also operate at 64 MHz, we demonstrate the feasibility of integrating our radiometer with an MRI scanner to monitor RF power deposition and temperature dosimetry, obtaining coarse, spatially resolved, absolute thermal maps in the physiological range. We conclude that RF radiometry offers promise as a direct, noninvasive method of monitoring tissue heating during MRI studies and thereby providing an independent means of verifying patient-safe operation. Other potential applications include titration of hyper- and hypo-therapies. PMID:18026562

  19. [Reformatting 3-dimensional medical images. Application to MRI and scanners].

    PubMed

    Cuchet, E; Lambert, F; Derosier, C

    1994-04-01

    Several kinds of images, each giving a different information, are now available to radiologists. The MRI images have excellent contrast resolution and enable soft tissues to be differentiated, but they do not distinguish structures with low water content, notably air and bone, whereas these are easily recognized by CT. The aim of this study is to present a simple, entirely radiologist-supervised method to examine the radiological data of any patient, obtained from several kinds of images. MRI is performed using a GEMS Signa, 1.5 Tesla, 4.9 version magnet. Acquisitions are T1- or T2-weighted spin-echo or gradient sequences, with a 256 or 512 matrix, on axial sections, with of without contrast injection. CT is performed using a GEMS Hi Speed scanner. Acquisitions are obtained on a 512 matrix and with a "Soft" or "Bone" filter, without contrast injection. The two series of sections are transmitted, through an Etherne network, to a Sun console where the two corresponding volumes are reconstructed on a GEMS Voxtol by means of a 3-dimensional soft ware for image treatment. At least 3 couples define the rotation and translation required for one of the two volumes to reset it in the guide mark of the other. The soft ware then looks for the best transformation, in terms of least square, between the two 3-dimensional volumes. The calculation demands only a few seconds. One of the two objects is then recalculated in the guide mark of the other. The cursor positioned by the user on any point of the object is linked to a second cursor which will automatically position itself on the corresponding point of the other object. The accuracy obtained (about one millimeter) is specified by the soft ware which indicates how to improve resetting. In addition to its teaching value, this superimposition image can help in the diagnosis and can be used for surgical stimulation because it is possible to mix the images. This mixing gives access to a new type of imaging, since the images spared

  20. MRI scanner-independent specific absorption rate measurements using diffusion coefficients.

    PubMed

    Seo, Youngseob; Wang, Zhiyue J

    2017-07-01

    The purpose of this study was to measure specific absorption rate (SAR) during MRI scanning using a human torso phantom through quantification of diffusion coefficients independently of those reported by the scanner software for five 1.5 and 3 T clinical MRI systems from different vendors. A quadrature body coil transmitted the RF power and a body array coil received the signals. With diffusion tensor imaging, SAR values for three MRI sequences were measured on the five scanners and compared to the nominal values calculated by the scanners. For the GE 1.5 T MRI system, the MRI scanner-reported SAR value was 1.58 W kg(-1) and the measured SAR value was 1.38 W kg(-1) . For the Philips 1.5 T MRI scanner, the MRI system-reported SAR value was 1.48 W kg(-1) and the measured value was 1.39 W kg(-1) . For the Siemens 3 T MRI system, the reported SAR value was 2.5 W kg(-1) and the measured SAR value was 1.96 W kg(-1) . For two Philips 3 T MRI scanners, the reported SAR values were 1.5 W kg(-1) and the measured values were 1.94 and 1.96 W kg(-1) . The percentage differences between the measured and reported SAR values on the GE 1.5 T, Philips 1.5 T, Siemens 3 T, and Philips 3 T were 13.5, 6.3, 24.2, 25.6, and 26.6% respectively. The scanner-independent SAR measurements using diffusion coefficients described in this study can play a significant role in estimating accurate SAR values as a standardized method. © 2017 The Authors. Journal of Applied Clinical Medical Physics published by Wiley Periodicals, Inc. on behalf of American Association of Physicists in Medicine.

  1. Evaluation of a positron emission tomography (PET)-compatible field-cycled MRI (FCMRI) scanner.

    PubMed

    Gilbert, Kyle M; Scholl, Timothy J; Handler, William B; Alford, Jamu K; Chronik, Blaine A

    2009-10-01

    Field-cycled MRI (FCMRI) uses two independent, actively controlled resistive magnets to polarize a sample and to provide the magnetic field environment during data acquisition. This separation of tasks allows for novel forms of contrast, reduction of susceptibility artifacts, and a versatility in design that facilitates the integration of a second imaging modality. A 0.3T/4-MHz FCMRI scanner was constructed with a 9-cm-wide opening through the side for the inclusion of a photomultiplier-tube-based positron emission tomography (PET) system. The performance of the FCMRI scanner was evaluated prior to integrating PET detectors. Quantitative measurements of the system's signal, phase, and temperature were recorded. The polarizing and readout magnets could be operated continuously at 100 A without risk of damage to the system. Transient instabilities in the readout magnet, caused by the pulsing of the polarizing magnet, dissipated in 50 ms; this resulted in a steady-state homogeneity of 32 Hz over a 7-cm-diameter volume. The short- and long-term phase behaviors of the readout field were sufficiently stable to prevent visible readout or phase-encode artifacts during imaging. Preliminary MR images demonstrated the potential of the FCMRI scanner and the efficacy of integrating a PET system. (c) 2009 Wiley-Liss, Inc.

  2. Initial results of simultaneous PET/MRI experiments with an MRI-compatible silicon photomultiplier PET scanner.

    PubMed

    Yoon, Hyun Suk; Ko, Guen Bae; Kwon, Sun Il; Lee, Chan Mi; Ito, Mikiko; Chan Song, In; Lee, Dong Soo; Hong, Seong Jong; Lee, Jae Sung

    2012-04-01

    The most investigated semiconductor photosensor for MRI-compatible PET detectors is the avalanche photodiode (APD). However, the silicon photomultiplier (SiPM), also called the Geiger-mode APD, is gaining attention in the development of the next generation of PET/MRI systems because the SiPM has much better performance than the APD. We have developed an MRI-compatible PET system based on multichannel SiPM arrays to allow simultaneous PET/MRI. The SiPM PET scanner consists of 12 detector modules with a ring diameter of 13.6 cm and an axial extent of 3.2 cm. In each detector module, 4 multichannel SiPM arrays (with 4 × 4 channels arranged in a 2 × 2 array to yield 8 × 8 channels) were coupled with 20 × 18 Lu(1.9)Gd(0.1)SiO(5):Ce crystals (each crystal is 1.5 × 1.5 × 7 mm) and mounted on a charge division network for multiplexing 64 signals into 4 position signals. Each detector module was enclosed in a shielding box to reduce interference between the PET and MRI scanners, and the temperature inside the box was monitored for correction of the temperature-dependent gain variation of the SiPM. The PET detector signal was routed to the outside of the MRI room and processed with a field programmable gate array-based data acquisition system. MRI compatibility tests and simultaneous PET/MRI acquisitions were performed inside a 3-T clinical MRI system with 4-cm loop receiver coils that were built into the SiPM PET scanner. Interference between the imaging systems was investigated, and phantom and mouse experiments were performed. No radiofrequency interference on the PET signal or degradation in the energy spectrum and flood map was shown during simultaneous PET/MRI. The quality of the MRI scans acquired with and without the operating PET showed only slight degradation. The results of phantom and mouse experiments confirmed the feasibility of this system for simultaneous PET/MRI. Simultaneous PET/MRI was possible with a multichannel SiPM-based PET scanner, with no

  3. Static field influences on transcranial magnetic stimulation: considerations for TMS in the scanner environment.

    PubMed

    Yau, Jeffrey M; Jalinous, Reza; Cantarero, Gabriela L; Desmond, John E

    2014-01-01

    Transcranial magnetic stimulation (TMS) can be combined with functional magnetic resonance imaging (fMRI) to simultaneously manipulate and monitor human cortical responses. Although tremendous efforts have been directed at characterizing the impact of TMS on image acquisition, the influence of the scanner's static field on the TMS coil has received limited attention. The aim of this study was to characterize the influence of the scanner's static field on TMS. We hypothesized that spatial variations in the static field could account for TMS field variations in the scanner environment. Using an MRI-compatible TMS coil, we estimated TMS field strengths based on TMS-induced voltage changes measured in a search coil. We compared peak field strengths obtained with the TMS coil positioned at different locations (B0 field vs fringe field) and orientations in the static field. We also measured the scanner's static field to derive a field map to account for TMS field variations. TMS field strength scaled depending on coil location and orientation with respect to the static field. Larger TMS field variations were observed in fringe field regions near the gantry as compared to regions inside the bore or further removed from the bore. The scanner's static field also exhibited the greatest spatial variations in fringe field regions near the gantry. The scanner's static field influences TMS fields and spatial variations in the static field correlate with TMS field variations. Coil orientation changes in the B0 field did not result in substantial TMS field variations. TMS field variations can be minimized by delivering TMS in the bore or outside of the 0-70 cm region from the bore entrance. Copyright © 2014 Elsevier Inc. All rights reserved.

  4. Structural-acoustic modal analysis of cylindrical shells: application to MRI scanner systems.

    PubMed

    Li, Gemin; Mechefske, Chris K

    2009-12-01

    The acoustic noise in a magnetic resonance imaging (MRI) scanner bore is mainly introduced by the vibration of gradient coils. The interaction between acoustic modes in the scanner bore and structure modes in the coil structure leads to structural-acoustic coupling. In order to implement quiet MRI design, the structural-acoustic coupling mechanism in MRI machines needs to be fully investigated. Structural analysis was first implemented using Love's classical shell theory. The concept of a "virtually closed cavity" was used in the acoustic modal analysis of the gradient coil duct. The dispersion curves and the number of modes per frequency band were used to reveal modal distribution properties for both structural modes and acoustic modes. Structural-acoustic coupling modes were identified by superposition of the dispersion diagrams of the structural waves and acoustic waves. Experimental validation was implemented separately for the structural analysis and acoustic analysis. Independent structural modes and acoustic modes and their distribution patterns were calculated up to 3000Hz with various boundary conditions. Coupling modes were clearly revealed using the analysis procedures presented in this paper and were found to be in agreement with the ones identified from experimental measurements. These methods are effective for coupled and uncoupled modal analysis of MRI scanner systems and can be used for quiet MRI design or sound absorber design for existing MRI systems.

  5. Comprehensive MRI simulation methodology using a dedicated MRI scanner in radiation oncology for external beam radiation treatment planning

    SciTech Connect

    Paulson, Eric S.; Erickson, Beth; Schultz, Chris; Allen Li, X.

    2015-01-15

    Purpose: The use of magnetic resonance imaging (MRI) in radiation oncology is expanding rapidly, and more clinics are integrating MRI into their radiation therapy workflows. However, radiation therapy presents a new set of challenges and places additional constraints on MRI compared to diagnostic radiology that, if not properly addressed, can undermine the advantages MRI offers for radiation treatment planning (RTP). The authors introduce here strategies to manage several challenges of using MRI for virtual simulation in external beam RTP. Methods: A total of 810 clinical MRI simulation exams were performed using a dedicated MRI scanner for external beam RTP of brain, breast, cervix, head and neck, liver, pancreas, prostate, and sarcoma cancers. Patients were imaged in treatment position using MRI-optimal immobilization devices. Radiofrequency (RF) coil configurations and scan protocols were optimized based on RTP constraints. Off-resonance and gradient nonlinearity-induced geometric distortions were minimized or corrected prior to using images for RTP. A multidisciplinary MRI simulation guide, along with window width and level presets, was created to standardize use of MR images during RTP. A quality assurance program was implemented to maintain accuracy and repeatability of MRI simulation exams. Results: The combination of a large bore scanner, high field strength, and circumferentially wrapped, flexible phased array RF receive coils permitted acquisition of thin slice images with high contrast-to-noise ratio (CNR) and image intensity uniformity, while simultaneously accommodating patient setup and immobilization devices. Postprocessing corrections and alternative acquisition methods were required to reduce or correct off-resonance and gradient nonlinearity induced geometric distortions. Conclusions: The methodology described herein contains practical strategies the authors have implemented through lessons learned performing clinical MRI simulation exams. In

  6. Spatial Distortion in MRI-Guided Stereotactic Procedures: Evaluation in 1.5-, 3- and 7-Tesla MRI Scanners.

    PubMed

    Neumann, Jan-Oliver; Giese, Henrik; Biller, Armin; Nagel, Armin M; Kiening, Karl

    2015-01-01

    Magnetic resonance imaging (MRI) is replacing computed tomography (CT) as the main imaging modality for stereotactic transformations. MRI is prone to spatial distortion artifacts, which can lead to inaccuracy in stereotactic procedures. Modern MRI systems provide distortion correction algorithms that may ameliorate this problem. This study investigates the different options of distortion correction using standard 1.5-, 3- and 7-tesla MRI scanners. A phantom was mounted on a stereotactic frame. One CT scan and three MRI scans were performed. At all three field strengths, two 3-dimensional sequences, volumetric interpolated breath-hold examination (VIBE) and magnetization-prepared rapid acquisition with gradient echo, were acquired, and automatic distortion correction was performed. Global stereotactic transformation of all 13 datasets was performed and two stereotactic planning workflows (MRI only vs. CT/MR image fusion) were subsequently analysed. Distortion correction on the 1.5- and 3-tesla scanners caused a considerable reduction in positional error. The effect was more pronounced when using the VIBE sequences. By using co-registration (CT/MR image fusion), even a lower positional error could be obtained. In ultra-high-field (7 T) MR imaging, distortion correction introduced even higher errors. However, the accuracy of non-corrected 7-tesla sequences was comparable to CT/MR image fusion 3-tesla imaging. MRI distortion correction algorithms can reduce positional errors by up to 60%. For stereotactic applications of utmost precision, we recommend a co-registration to an additional CT dataset. © 2015 S. Karger AG, Basel.

  7. MRI-assisted PET motion correction for neurologic studies in an integrated MR-PET scanner.

    PubMed

    Catana, Ciprian; Benner, Thomas; van der Kouwe, Andre; Byars, Larry; Hamm, Michael; Chonde, Daniel B; Michel, Christian J; El Fakhri, Georges; Schmand, Matthias; Sorensen, A Gregory

    2011-01-01

    Head motion is difficult to avoid in long PET studies, degrading the image quality and offsetting the benefit of using a high-resolution scanner. As a potential solution in an integrated MR-PET scanner, the simultaneously acquired MRI data can be used for motion tracking. In this work, a novel algorithm for data processing and rigid-body motion correction (MC) for the MRI-compatible BrainPET prototype scanner is described, and proof-of-principle phantom and human studies are presented. To account for motion, the PET prompt and random coincidences and sensitivity data for postnormalization were processed in the line-of-response (LOR) space according to the MRI-derived motion estimates. The processing time on the standard BrainPET workstation is approximately 16 s for each motion estimate. After rebinning in the sinogram space, the motion corrected data were summed, and the PET volume was reconstructed using the attenuation and scatter sinograms in the reference position. The accuracy of the MC algorithm was first tested using a Hoffman phantom. Next, human volunteer studies were performed, and motion estimates were obtained using 2 high-temporal-resolution MRI-based motion-tracking techniques. After accounting for the misalignment between the 2 scanners, perfectly coregistered MRI and PET volumes were reproducibly obtained. The MRI output gates inserted into the PET list-mode allow the temporal correlation of the 2 datasets within 0.2 ms. The Hoffman phantom volume reconstructed by processing the PET data in the LOR space was similar to the one obtained by processing the data using the standard methods and applying the MC in the image space, demonstrating the quantitative accuracy of the procedure. In human volunteer studies, motion estimates were obtained from echo planar imaging and cloverleaf navigator sequences every 3 s and 20 ms, respectively. Motion-deblurred PET images, with excellent delineation of specific brain structures, were obtained using these 2 MRI

  8. MR Scanner Systems Should Be Adequately Characterized in Diffusion-MRI of the Breast

    PubMed Central

    Giannelli, Marco; Sghedoni, Roberto; Iacconi, Chiara; Iori, Mauro; Traino, Antonio Claudio; Guerrisi, Maria; Mascalchi, Mario; Toschi, Nicola; Diciotti, Stefano

    2014-01-01

    Breast imaging represents a relatively recent and promising field of application of quantitative diffusion-MRI techniques. In view of the importance of guaranteeing and assessing its reliability in clinical as well as research settings, the aim of this study was to specifically characterize how the main MR scanner system-related factors affect quantitative measurements in diffusion-MRI of the breast. In particular, phantom acquisitions were performed on three 1.5 T MR scanner systems by different manufacturers, all equipped with a dedicated multi-channel breast coil as well as acquisition sequences for diffusion-MRI of the breast. We assessed the accuracy, inter-scan and inter-scanner reproducibility of the mean apparent diffusion coefficient measured along the main orthogonal directions () as well as of diffusion-tensor imaging (DTI)-derived mean diffusivity (MD) measurements. Additionally, we estimated spatial non-uniformity of (NU) and MD (NUMD) maps. We showed that the signal-to-noise ratio as well as overall calibration of high strength diffusion gradients system in typical acquisition sequences for diffusion-MRI of the breast varied across MR scanner systems, introducing systematic bias in the measurements of diffusion indices. While and MD values were not appreciably different from each other, they substantially varied across MR scanner systems. The mean of the accuracies of measured and MD was in the range [−2.3%,11.9%], and the mean of the coefficients of variation for and MD measurements across MR scanner systems was 6.8%. The coefficient of variation for repeated measurements of both and MD was < 1%, while NU and NUMD values were <4%. Our results highlight that MR scanner system-related factors can substantially affect quantitative diffusion-MRI of the breast. Therefore, a specific quality control program for assessing and monitoring the performance of MR scanner systems for diffusion-MRI of the breast is

  9. Small PET scanner based on MRI-compatible light sensor

    NASA Astrophysics Data System (ADS)

    Molnar, J.; Balkay, L.; Berenyi, E.

    2015-03-01

    Improving the quality of life of elderly people requires diagnostic and therapeutic capabilities for diseases of the central nervous system, such as Alzheimer's, Parkinson's, and epilepsy which have a rapidly growing impact on society. Minimallyinvasive imaging technologies such as PET and MRI allow for monitoring and tracking these illnesses, starting from their preliminary manifestations.

  10. Who gets afraid in the MRI-scanner? Neurogenetics of state-anxiety changes during an fMRI experiment.

    PubMed

    Mutschler, Isabella; Wieckhorst, Birgit; Meyer, Andrea H; Schweizer, Tina; Klarhöfer, Markus; Wilhelm, Frank H; Seifritz, Erich; Ball, Tonio

    2014-11-07

    Experiments using functional magnetic resonance imaging (fMRI) play a fundamental role in affective neuroscience. When placed in an MR scanner, some volunteers feel safe and relaxed in this situation, while others experience uneasiness and fear. Little is known about the basis and consequences of such inter-individually different responses to the general experimental fMRI setting. In this study emotional stimuli were presented during fMRI and subjects' state-anxiety was assessed at the onset and end of the experiment while they were within the scanner. We show that Val/Val but neither Met/Met nor Val/Met carriers of the catechol-O-methyltransferase (COMT) Val(158)Met polymorphism-a prime candidate for anxiety vulnerability-became significantly more anxious during the fMRI experiment (N=97 females: 24 Val/Val, 51 Val/Met, and 22 Met/Met). Met carriers demonstrated brain responses with increased stability over time in the right parietal cortex and significantly better cognitive performances likely mediated by lower levels of anxiety. Val/Val, Val/Met and Met/Met did not significantly differ in state-anxiety at the beginning of the experiment. The exposure of a control group (N=56 females) to the same experiment outside the scanner did not cause a significant increase in state-anxiety, suggesting that the increase we observe in the fMRI experiment may be specific to the fMRI setting. Our findings reveal that genetics may play an important role in shaping inter-individual different emotional, cognitive and neuronal responses during fMRI experiments. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  11. A Novel Method for Quantifying Scanner Instability in fMRI

    PubMed Central

    Greve, Douglas N.; Mueller, Bryon A.; Liu, Thomas; Turner, Jessica A.; Voyvodic, James; Yetter, Elizabeth; Diaz, Michele; McCarthy, Gregory; Wallace, Stuart; Roach, Brian J.; Ford, Judy M.; Mathalon, Daniel H.; Calhoun, Vince D.; Wible, Cynthia G.; Potkin, Stephen G.; Glover, Gary

    2010-01-01

    A method was developed to quantify the effect of scanner instability on fMRI data by comparing the instability noise to endogenous noise present when scanning a human. The instability noise was computed from agar phantom data collected with two flip angles, allowing for a separation of the instability from the background noise. This method was used on human data collected at four 3T scanners, allowing the physiological noise level to be extracted from the data. In a “well-operating” scanner, the instability noise is generally less than 10% of physiological noise in white matter and only about 2% of physiological noise in cortex. This indicates that instability in a well-operating scanner adds very little noise to fMRI results. This new method allows researchers to make informed decisions about the maximum instability level a scanner can have before it is taken off line for maintenance or rejected from a multisite consortium. This method also provides information about the background noise, which is generally larger in magnitude than the instability noise. PMID:21413069

  12. Inter-site and inter-scanner diffusion MRI data harmonization.

    PubMed

    Mirzaalian, H; Ning, L; Savadjiev, P; Pasternak, O; Bouix, S; Michailovich, O; Grant, G; Marx, C E; Morey, R A; Flashman, L A; George, M S; McAllister, T W; Andaluz, N; Shutter, L; Coimbra, R; Zafonte, R D; Coleman, M J; Kubicki, M; Westin, C F; Stein, M B; Shenton, M E; Rathi, Y

    2016-07-15

    We propose a novel method to harmonize diffusion MRI data acquired from multiple sites and scanners, which is imperative for joint analysis of the data to significantly increase sample size and statistical power of neuroimaging studies. Our method incorporates the following main novelties: i) we take into account the scanner-dependent spatial variability of the diffusion signal in different parts of the brain; ii) our method is independent of compartmental modeling of diffusion (e.g., tensor, and intra/extra cellular compartments) and the acquired signal itself is corrected for scanner related differences; and iii) inter-subject variability as measured by the coefficient of variation is maintained at each site. We represent the signal in a basis of spherical harmonics and compute several rotation invariant spherical harmonic features to estimate a region and tissue specific linear mapping between the signal from different sites (and scanners). We validate our method on diffusion data acquired from seven different sites (including two GE, three Philips, and two Siemens scanners) on a group of age-matched healthy subjects. Since the extracted rotation invariant spherical harmonic features depend on the accuracy of the brain parcellation provided by Freesurfer, we propose a feature based refinement of the original parcellation such that it better characterizes the anatomy and provides robust linear mappings to harmonize the dMRI data. We demonstrate the efficacy of our method by statistically comparing diffusion measures such as fractional anisotropy, mean diffusivity and generalized fractional anisotropy across multiple sites before and after data harmonization. We also show results using tract-based spatial statistics before and after harmonization for independent validation of the proposed methodology. Our experimental results demonstrate that, for nearly identical acquisition protocol across sites, scanner-specific differences can be accurately removed using the

  13. Simulation Study on Active Noise Control for a 4 Tesla MRI Scanner

    PubMed Central

    Li, Mingfeng; Lim, Teik C.; Lee, Jing-Huei

    2008-01-01

    The purpose of this work is to study computationally the possibility of the application of a hybrid active noise control technique for MRI acoustic noise reduction. A hybrid control system combined with both feedforward and feedback loops embedded is proposed for potential application on active MRI noise reduction. A set of computational simulation studies were performed. Sets of MRI acoustic noise emissions measured at the patient's left ear location were recorded and used in the simulation study. By comparing three different control systems, namely the feedback, the feedforward and the hybrid control, our results revealed that the hybrid control system is the most effective. The hybrid control system achieved approximately a 20 dB reduction at the principal frequency component. We concluded that the proposed hybrid active control scheme could have a potential application for MRI scanner noise reduction. PMID:18060719

  14. Simulation study on active noise control for a 4-T MRI scanner.

    PubMed

    Li, Mingfeng; Lim, Teik C; Lee, Jing-Huei

    2008-04-01

    The purpose of this work is to study computationally the possibility of the application of a hybrid active noise control technique for magnetic resonance imaging (MRI) acoustic noise reduction. A hybrid control system combined with both feedforward and feedback loops embedded is proposed for potential application on active MRI noise reduction. A set of computational simulation studies were performed. Sets of MRI acoustic noise emissions measured at the patient's left ear location were recorded and used in the simulation study. By comparing three different control systems, namely, the feedback, the feedforward and the hybrid control, our results revealed that the hybrid control system is the most effective. The hybrid control system achieved approximately a 20-dB reduction at the principal frequency component. We concluded that the proposed hybrid active control scheme could have a potential application for MRI scanner noise reduction.

  15. Development of a PET Scanner for Simultaneously Imaging Small Animals with MRI and PET

    PubMed Central

    Thompson, Christopher J; Goertzen, Andrew L; Thiessen, Jonathan D; Bishop, Daryl; Stortz, Greg; Kozlowski, Piotr; Retière, Fabrice; Zhang, Xuezhu; Sossi, Vesna

    2014-01-01

    Recently, positron emission tomography (PET) is playing an increasingly important role in the diagnosis and staging of cancer. Combined PET and X-ray computed tomography (PET-CT) scanners are now the modality of choice in cancer treatment planning. More recently, the combination of PET and magnetic resonance imaging (MRI) is being explored in many sites. Combining PET and MRI has presented many challenges since the photo-multiplier tubes (PMT) in PET do not function in high magnetic fields, and conventional PET detectors distort MRI images. Solid state light sensors like avalanche photo-diodes (APDs) and more recently silicon photo-multipliers (SiPMs) are much less sensitive to magnetic fields thus easing the compatibility issues. This paper presents the results of a group of Canadian scientists who are developing a PET detector ring which fits inside a high field small animal MRI scanner with the goal of providing simultaneous PET and MRI images of small rodents used in pre-clinical medical research. We discuss the evolution of both the crystal blocks (which detect annihilation photons from positron decay) and the SiPM array performance in the last four years which together combine to deliver significant system performance in terms of speed, energy and timing resolution. PMID:25120157

  16. Occupational exposure measurements of static and pulsed gradient magnetic fields in the vicinity of MRI scanners.

    PubMed

    Kännälä, Sami; Toivo, Tim; Alanko, Tommi; Jokela, Kari

    2009-04-07

    Recent advances in magnetic resonance imaging (MRI) have increased occupational exposure to magnetic fields. In this study, we examined the assessment of occupational exposure to gradient magnetic fields and time-varying magnetic fields generated by motion in non-homogeneous static magnetic fields of MRI scanners. These magnetic field components can be measured simultaneously with an induction coil setup that detects the time rate of change of magnetic flux density (dB/dt). The setup developed was used to measure the field components around two MRI units (1 T open and 3 T conventional). The measured values can be compared with dB/dt reference levels derived from magnetic flux density reference levels given by the International Commission on Non-Ionizing Radiation Protection (ICNIRP). The measured motion-induced dB/dt values were above the dB/dt reference levels for both MRI units. The measured values for the gradient fields (echo planar imaging (EPI) and fast field echo (FFE) sequences) also exceeded the dB/dt reference levels in positions where the medical staff may have access during interventional procedures. The highest motion-induced dB/dt values were 0.7 T s(-1) for the 1 T scanner and 3 T s(-1) for the 3 T scanner when only the static field was present. Even higher values (6.5 T s(-1)) were measured for simultaneous exposure to motion-induced and gradient fields in the vicinity of the 3 T scanner.

  17. Wrong detection of ventricular fibrillation in an implantable cardioverter defibrillator caused by the movement near the MRI scanner bore.

    PubMed

    Mattei, Eugenio; Censi, Federica; Triventi, Michele; Mancini, Matteo; Napolitano, Antonio; Genovese, Elisabetta; Cannata, Vittorio; Falsaperla, Rosaria; Calcagnini, Giovanni

    2015-01-01

    The static magnetic field generated by MRI systems is highly non-homogenous and rapidly decreases when moving away from the bore of the scanner. Consequently, the movement around the MRI scanner is equivalent to an exposure to a time-varying magnetic field at very low frequency (few Hz). For patients with an implanted cardiac stimulators, such as an implantable cardioverter/defibrillator (ICD), the movements inside the MRI environment may thus induce voltages on the loop formed by the leads of the device, with the potential to affect the behavior of the stimulator. In particular, the ICD's detection algorithms may be affected by the induced voltage and may cause inappropriate sensing, arrhythmia detections, and eventually inappropriate ICD therapy.We performed in-vitro measurements on a saline-filled humanshaped phantom (male, 170 cm height), equipped with an MRconditional ICD able to transmit in real-time the detected cardiac activity (electrograms). A biventricular implant was reproduced and the ICD was programmed in standard operating conditions, but with the shock delivery disabled. The electrograms recorded in the atrial, left and right ventricle channels were monitored during rotational movements along the vertical axis, in close proximity of the bore. The phantom was also equipped with an accelerometer and a magnetic field probe to measure the angular velocity and the magnetic field variation during the experiment. Pacing inhibition, inappropriate detection of tachyarrhythmias and of ventricular fibrillation were observed. Pacing inhibition began at an angular velocity of about 7 rad/s, (dB/dt of about 2 T/s). Inappropriate detection of ventricular fibrillation occurred at about 8 rad/s (dB/dt of about 3 T/s). These findings highlight the need for a specific risk assessment of workers with MR-conditional ICDs, which takes into account also effects that are generally not considered relevant for patients, such as the movement around the scanner bore.

  18. EEG-MRI co-registration and sensor labeling using a 3D laser scanner.

    PubMed

    Koessler, L; Cecchin, T; Caspary, O; Benhadid, A; Vespignani, H; Maillard, L

    2011-03-01

    This paper deals with the co-registration of an MRI scan with EEG sensors. We set out to evaluate the effectiveness of a 3D handheld laser scanner, a device that is not widely used for co-registration, applying a semi-automatic procedure that also labels EEG sensors. The scanner acquired the sensors' positions and the face shape, and the scalp mesh was obtained from the MRI scan. A pre-alignment step, using the position of three fiducial landmarks, provided an initial value for co-registration, and the sensors were automatically labeled. Co-registration was then performed using an iterative closest point algorithm applied to the face shape. The procedure was conducted on five subjects with two scans of EEG sensors and one MRI scan each. The mean time for the digitization of the 64 sensors and three landmarks was 53 s. The average scanning time for the face shape was 2 min 6 s for an average number of 5,263 points. The mean residual error of the sensors co-registration was 2.11 mm. These results suggest that the laser scanner associated with an efficient co-registration and sensor labeling algorithm is sufficiently accurate, fast and user-friendly for longitudinal and retrospective brain sources imaging studies.

  19. Silent speechreading in the absence of scanner noise: an event-related fMRI study.

    PubMed

    MacSweeney, M; Amaro, E; Calvert, G A; Campbell, R; David, A S; McGuire, P; Williams, S C; Woll, B; Brammer, M J

    2000-06-05

    In a previous study we used functional magnetic resonance imaging (fMRI) to demonstrate activation in auditory cortex during silent speechreading. Since image acquisition during fMRI generates acoustic noise, this pattern of activation could have reflected an interaction between background scanner noise and the visual lip-read stimuli. In this study we employed an event-related fMRI design which allowed us to measure activation during speechreading in the absence of acoustic scanner noise. In the experimental condition, hearing subjects were required to speechread random numbers from a silent speaker. In the control condition subjects watched a static image of the same speaker with mouth closed and were required to subvocally count an intermittent visual cue. A single volume of images was collected to coincide with the estimated peak of the blood oxygen level dependent (BOLD) response to these stimuli across multiple baseline and experimental trials. Silent speechreading led to greater activation in lateral temporal cortex relative to the control condition. This indicates that activation of auditory areas during silent speechreading is not a function of acoustic scanner noise and confirms that silent speechreading engages similar regions of auditory cortex as listening to speech.

  20. Subtle In-Scanner Motion Biases Automated Measurement of Brain Anatomy From In Vivo MRI

    PubMed Central

    Alexander-Bloch, Aaron; Clasen, Liv; Stockman, Michael; Ronan, Lisa; Lalonde, Francois; Giedd, Jay; Raznahan, Armin

    2016-01-01

    While the potential for small amounts of motion in functional magnetic resonance imaging (fMRI) scans to bias the results of functional neuroimaging studies is well appreciated, the impact of in-scanner motion on morphological analysis of structural MRI is relatively under-studied. Even among “good quality” structural scans, there may be systematic effects of motion on measures of brain morphometry. In the present study, the subjects’ tendency to move during fMRI scans, acquired in the same scanning sessions as their structural scans, yielded a reliable, continuous estimate of in-scanner motion. Using this approach within a sample of 127 children, adolescents, and young adults, significant relationships were found between this measure and estimates of cortical gray matter volume and mean curvature, as well as trend-level relationships with cortical thickness. Specifically, cortical volume and thickness decreased with greater motion, and mean curvature increased. These effects of subtle motion were anatomically heterogeneous, were present across different automated imaging pipelines, showed convergent validity with effects of frank motion assessed in a separate sample of 274 scans, and could be demonstrated in both pediatric and adult populations. Thus, using different motion assays in two large non-overlapping sets of structural MRI scans, convergent evidence showed that in-scanner motion—even at levels which do not manifest in visible motion artifact—can lead to systematic and regionally specific biases in anatomical estimation. These findings have special relevance to structural neuroimaging in developmental and clinical datasets, and inform ongoing efforts to optimize neuroanatomical analysis of existing and future structural MRI datasets in non-sedated humans. PMID:27004471

  1. Three-dimensional contrasted visualization of pancreas in rats using clinical MRI and CT scanners.

    PubMed

    Yin, Ting; Coudyzer, Walter; Peeters, Ronald; Liu, Yewei; Cona, Marlein Miranda; Feng, Yuanbo; Xia, Qian; Yu, Jie; Jiang, Yansheng; Dymarkowski, Steven; Huang, Gang; Chen, Feng; Oyen, Raymond; Ni, Yicheng

    2015-01-01

    The purpose of this work was to visualize the pancreas in post-mortem rats with local contrast medium infusion by three-dimensional (3D) magnetic resonance imaging (MRI) and computed tomography (CT) using clinical imagers. A total of 16 Sprague Dawley rats of about 300 g were used for the pancreas visualization. Following the baseline imaging, a mixed contrast medium dye called GadoIodo-EB containing optimized concentrations of Gd-DOTA, iomeprol and Evens blue was infused into the distally obstructed common bile duct (CBD) for post-contrast imaging with 3.0 T MRI and 128-slice CT scanners. Images were post-processed with the MeVisLab software package. MRI findings were co-registered with CT scans and validated with histomorphology, with relative contrast ratios quantified. Without contrast enhancement, the pancreas was indiscernible. After infusion of GadoIodo-EB solution, only the pancreatic region became outstandingly visible, as shown by 3D rendering MRI and CT and proven by colored dissection and histological examinations. The measured volume of the pancreas averaged 1.12 ± 0.04 cm(3) after standardization. Relative contrast ratios were 93.28 ± 34.61% and 26.45 ± 5.29% for MRI and CT respectively. We have developed a multifunctional contrast medium dye to help clearly visualize and delineate rat pancreas in situ using clinical MRI and CT scanners. The topographic landmarks thus created with 3D demonstration may help to provide guidelines for the next in vivo pancreatic MRI research in rodents. Copyright © 2015 John Wiley & Sons, Ltd.

  2. Simultaneous and interleaved acquisition of NMR signals from different nuclei with a clinical MRI scanner

    PubMed Central

    Magill, Arthur W.; Kuehne, Andre; Gruetter, Rolf; Moser, Ewald; Schmid, Albrecht Ingo

    2015-01-01

    Purpose Modification of a clinical MRI scanner to enable simultaneous or rapid interleaved acquisition of signals from two different nuclei. Methods A device was developed to modify the local oscillator signal fed to the receive channel(s) of an MRI console. This enables external modification of the frequency at which the receiver is sensitive and rapid switching between different frequencies. Use of the device was demonstrated with interleaved and simultaneous 31P and 1H spectroscopic acquisitions, and with interleaved 31P and 1H imaging. Results Signal amplitudes and signal‐to‐noise ratios were found to be unchanged for the modified system, compared with data acquired with the MRI system in the standard configuration. Conclusion Interleaved and simultaneous 1H and 31P signal acquisition was successfully demonstrated with a clinical MRI scanner, with only minor modification of the RF architecture. While demonstrated with 31P, the modification is applicable to any detectable nucleus without further modification, enabling a wide range of simultaneous and interleaved experiments to be performed within a clinical setting. Magn Reson Med 76:1636–1641, 2016. © 2015 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. PMID:26608834

  3. A modified rabbit model of stroke: evaluation using clinical MRI scanner.

    PubMed

    Yang, Ji-Ping; Liu, Huai-Jun; Liu, Rui-Chun

    2009-12-01

    Occluding the middle cerebral artery of small animals with an intraluminal filament to build a stroke model has gained increasing acceptance. In light of the growing demand for magnetic resonance imaging (MRI) studies using the clinical MRI scanner, large animal models can be superior to small animal models. In this work, we developed a modified rabbit model of stroke, which was assessed using clinical MRI scanner and compared with a most commonly silicone-coated filament model. We presented a focal cerebral ischemia in rabbits. The key feature of this modified method is the use of a guide wire as a 'nylon suture'. At 3 days after ischemia, the percentage of brain infarct volume, neurobehavioral score, intracranial hemorrhagic incidence and dynamic changes of T(2) and apparent diffusion coefficient values were assessed respectively and compared between the focal cerebral models. Wire-induced models had more severe brain infarct size with less dispersion (32.7 +/- 6.5%, coefficient of variation=0.20) than that with filament models (25.4 +/- 8.9%, coefficient of variation=0.31; p<0.05). There were more significant MRI changes in the early stage, higher rate of technique success (wire, 20/20; filament, 17/20) and less intracranial hemorrhage (wire, 0/20; filament, 3/20) in wire-induced models than in filament-induced rabbits (p<0.05). Our data suggest that wire-induced method can provide a useful tool for the earlier research of ischemia.

  4. The Interconnection of MRI Scanner and MR-Compatible Robotic Device: Synergistic Graphical User Interface to Form a Mechatronic System

    PubMed Central

    Özcan, Alpay; Tsekos, Nikolaos

    2011-01-01

    MRI scanner and magnetic resonance (MR)-compatible robotic devices are mechatronic systems. Without an interconnecting component, these two devices cannot be operated synergetically for medical interventions. In this paper, the design and properties of a graphical user interface (GUI) that accomplishes the task is presented. The GUI interconnects the two devices to obtain a larger mechatronic system by providing command and control of the robotic device based on the visual information obtained from the MRI scanner. Ideally, the GUI should also control imaging parameters of the MRI scanner. Its main goal is to facilitate image-guided interventions by acting as the synergistic component between the physician, the robotic device, the scanner, and the patient. PMID:21544216

  5. The Interconnection of MRI Scanner and MR-Compatible Robotic Device: Synergistic Graphical User Interface to Form a Mechatronic System.

    PubMed

    Ozcan, Alpay; Tsekos, Nikolaos

    2008-06-01

    MRI scanner and magnetic resonance (MR)-compatible robotic devices are mechatronic systems. Without an interconnecting component, these two devices cannot be operated synergetically for medical interventions. In this paper, the design and properties of a graphical user interface (GUI) that accomplishes the task is presented. The GUI interconnects the two devices to obtain a larger mechatronic system by providing command and control of the robotic device based on the visual information obtained from the MRI scanner. Ideally, the GUI should also control imaging parameters of the MRI scanner. Its main goal is to facilitate image-guided interventions by acting as the synergistic component between the physician, the robotic device, the scanner, and the patient.

  6. Interventional and intraoperative MRI at low field scanner--a review.

    PubMed

    Blanco, Roberto T; Ojala, Risto; Kariniemi, Juho; Perälä, Jukka; Niinimäki, Jaakko; Tervonen, Osmo

    2005-11-01

    Magnetic resonance imaging (MRI) is a cutting edge imaging modality in detecting diseases and pathologic tissue. The superior soft tissue contrast in MRI allows better definition of the pathology. MRI is increasingly used for guiding, monitoring and controlling percutaneous procedures and surgery. The rapid development of interventional techniques in radiology has led to integration of imaging with computers, new therapy devices and operating room like conditions. This has projected as faster and more accurate imaging and hence more demanding procedures have been applied to the repertoire of the interventional radiologist. In combining features of various other imaging modalities and adding some more into them, interventional MRI (IMRI) has potential to take further the interventional radiology techniques, minimally invasive therapies and surgery. The term "Interventional MRI" consists in short all those procedures, which are performed under MRI guidance. These procedures can be either percutaneous or open surgical of nature. One of the limiting factors in implementing MRI as guidance modality for interventional procedures has been the fact, that most widely used magnet design, a cylindrical magnet, is not ideal for guiding procedures as it does not allow direct access to the patient. Open, low field scanners usually operating around 0.2 T, offer this feature. Clumsy hardware, bad patient access, slow image update frequency and strong magnetic fields have been other limiting factors for interventional MRI. However, the advantages of MRI as an imaging modality have been so obvious that considerable development has taken place in the 20-year history of MRI. The image quality has become better, ever faster software, new innovative sequences, better MRI hardware and increased computing power have accelerated imaging speed and image quality to a totally new level. Perhaps the most important feature in the recent development has been the introduction of open

  7. 2D Imaging in a Lightweight Portable MRI Scanner without Gradient Coils

    PubMed Central

    Cooley, Clarissa Zimmerman; Stockmann, Jason P.; Armstrong, Brandon D.; Sarracanie, Mathieu; Lev, Michael H.; Rosen, Matthew S.; Wald, Lawrence L.

    2014-01-01

    Purpose As the premiere modality for brain imaging, MRI could find wider applicability if lightweight, portable systems were available for siting in unconventional locations such as Intensive Care Units, physician offices, surgical suites, ambulances, emergency rooms, sports facilities, or rural healthcare sites. Methods We construct and validate a truly portable (<100kg) and silent proof-of-concept MRI scanner which replaces conventional gradient encoding with a rotating lightweight cryogen-free, low-field magnet. When rotated about the object, the inhomogeneous field pattern is used as a rotating Spatial Encoding Magnetic field (rSEM) to create generalized projections which encode the iteratively reconstructed 2D image. Multiple receive channels are used to disambiguate the non-bijective encoding field. Results The system is validated with experimental images of 2D test phantoms. Similar to other non-linear field encoding schemes, the spatial resolution is position dependent with blurring in the center, but is shown to be likely sufficient for many medical applications. Conclusion The presented MRI scanner demonstrates the potential for portability by simultaneously relaxing the magnet homogeneity criteria and eliminating the gradient coil. This new architecture and encoding scheme shows convincing proof of concept images that are expected to be further improved with refinement of the calibration and methodology. PMID:24668520

  8. Validation of radiocarpal joint contact models based on images from a clinical MRI scanner.

    PubMed

    Johnson, Joshua E; McIff, Terence E; Lee, Phil; Toby, E Bruce; Fischer, Kenneth J

    2014-01-01

    This study was undertaken to assess magnetic resonance imaging (MRI)-based radiocarpal surface contact models of functional loading in a clinical MRI scanner for future in vivo studies, by comparison with experimental measures from three cadaver forearm specimens. Experimental data were acquired using a Tekscan sensor during simulated light grasp. Magnetic resonance (MR) images were used to obtain model geometry and kinematics (image registration). Peak contact pressures (PPs) and average contact pressures (APs), contact forces and contact areas were determined in the radiolunate and radioscaphoid joints. Contact area was also measured directly from MR images acquired with load and compared with model data. Based on the validation criteria (within 25% of experimental data), out of the six articulations (three specimens with two articulations each), two met the criterion for AP (0%, 14%); one for peak pressure (20%); one for contact force (5%); four for contact area with respect to experiment (8%, 13%, 19% and 23%), and three contact areas met the criterion with respect to direct measurements (14%, 21% and 21%). Absolute differences between model and experimental PPs were reasonably low (within 2.5 MPa). Overall, the results indicate that MRI-based models generated from 3T clinical MR scanner appear sufficient to obtain clinically relevant data.

  9. Effect of scanner acoustic background noise on strict resting-state fMRI

    PubMed Central

    Rondinoni, C.; Amaro, E.; Cendes, F.; Santos, A.C.dos; Salmon, C.E.G.

    2013-01-01

    Functional MRI (fMRI) resting-state experiments are aimed at identifying brain networks that support basal brain function. Although most investigators consider a ‘resting-state’ fMRI experiment with no specific external stimulation, subjects are unavoidably under heavy acoustic noise produced by the equipment. In the present study, we evaluated the influence of auditory input on the resting-state networks (RSNs). Twenty-two healthy subjects were scanned using two similar echo-planar imaging sequences in the same 3T MRI scanner: a default pulse sequence and a reduced “silent” pulse sequence. Experimental sessions consisted of two consecutive 7-min runs with noise conditions (default or silent) counterbalanced across subjects. A self-organizing group independent component analysis was applied to fMRI data in order to recognize the RSNs. The insula, left middle frontal gyrus and right precentral and left inferior parietal lobules showed significant differences in the voxel-wise comparison between RSNs depending on noise condition. In the presence of low-level noise, these areas Granger-cause oscillations in RSNs with cognitive implications (dorsal attention and entorhinal), while during high noise acquisition, these connectivities are reduced or inverted. Applying low noise MR acquisitions in research may allow the detection of subtle differences of the RSNs, with implications in experimental planning for resting-state studies, data analysis, and ergonomic factors. PMID:23579634

  10. MRI-derived measurements of human subcortical, ventricular and intracranial brain volumes: Reliability effects of scan sessions, acquisition sequences, data analyses, scanner upgrade, scanner vendors and field strengths.

    PubMed

    Jovicich, Jorge; Czanner, Silvester; Han, Xiao; Salat, David; van der Kouwe, Andre; Quinn, Brian; Pacheco, Jenni; Albert, Marilyn; Killiany, Ronald; Blacker, Deborah; Maguire, Paul; Rosas, Diana; Makris, Nikos; Gollub, Randy; Dale, Anders; Dickerson, Bradford C; Fischl, Bruce

    2009-05-15

    Automated MRI-derived measurements of in-vivo human brain volumes provide novel insights into normal and abnormal neuroanatomy, but little is known about measurement reliability. Here we assess the impact of image acquisition variables (scan session, MRI sequence, scanner upgrade, vendor and field strengths), FreeSurfer segmentation pre-processing variables (image averaging, B1 field inhomogeneity correction) and segmentation analysis variables (probabilistic atlas) on resultant image segmentation volumes from older (n=15, mean age 69.5) and younger (both n=5, mean ages 34 and 36.5) healthy subjects. The variability between hippocampal, thalamic, caudate, putamen, lateral ventricular and total intracranial volume measures across sessions on the same scanner on different days is less than 4.3% for the older group and less than 2.3% for the younger group. Within-scanner measurements are remarkably reliable across scan sessions, being minimally affected by averaging of multiple acquisitions, B1 correction, acquisition sequence (MPRAGE vs. multi-echo-FLASH), major scanner upgrades (Sonata-Avanto, Trio-TrioTIM), and segmentation atlas (MPRAGE or multi-echo-FLASH). Volume measurements across platforms (Siemens Sonata vs. GE Signa) and field strengths (1.5 T vs. 3 T) result in a volume difference bias but with a comparable variance as that measured within-scanner, implying that multi-site studies may not necessarily require a much larger sample to detect a specific effect. These results suggest that volumes derived from automated segmentation of T1-weighted structural images are reliable measures within the same scanner platform, even after upgrades; however, combining data across platform and across field-strength introduces a bias that should be considered in the design of multi-site studies, such as clinical drug trials. The results derived from the young groups (scanner upgrade effects and B1 inhomogeneity correction effects) should be considered as preliminary and in

  11. Integrated speech enhancement for functional MRI environment.

    PubMed

    Pathak, Nishank; Milani, Ali A; Panahi, Issa; Briggs, Richard

    2009-01-01

    This paper presents an integrated speech enhancement (SE) method for the noisy MRI environment. We show that the performance of SE system improves considerably when the speech signal dominated by MRI acoustic noise at very low SNR is enhanced in two successive stages using two-channel SE methods followed by a single-channel post processing SE algorithm. Actual MRI noisy speech data are used in our experiments showing the improved performance of the proposed SE method.

  12. Ag/AgCl electrodes in the EEG/fMRI method in 3T MRI scanner

    NASA Astrophysics Data System (ADS)

    Akay, Cengiz; Kepceoğlu, Abdullah

    2013-10-01

    This study focuses on the comparison of two different types of EEG electrodes (the first B10-S-150 Ag/AgCl sintered ring electrode with 1, 5 mm touch proof safety socket and 150 cm heavy-duty lead wire and the second, B12-LS-100 Ag/AgCl sintered FE-electrode with 100 cm light-duty lead wire and 1, 5 mm touch proof safety socket with 5 kΩ resistor near sensor) used in the EEG/fMRI method in 3T MRI scanner. We compared these electrodes by their specific absorption rate (SAR) simulation values and the temperature change calculated by PRF method. The experimental setup of the study is described as follows: a phantom is prepared and the electrodes are placed on it. Then, a simulation for SAR values is realized. The temperature change is calculated by MR thermometer. As a result of this study, Ag/AgCl pin electrode is better to be use in EEG/fMRI; because the measured temperature change is expected to be low.

  13. Acoustic pressure waves induced in human heads by RF pulses from high-field MRI scanners.

    PubMed

    Lin, James C; Wang, Zhangwei

    2010-04-01

    The current evolution toward greater image resolution from magnetic resonance image (MRI) scanners has prompted the exploration of higher strength magnetic fields and use of higher levels of radio frequencies (RFs). Auditory perception of RF pulses by humans has been reported during MRI with head coils. It has shown that the mechanism of interaction for the auditory effect is caused by an RF pulse-induced thermoelastic pressure wave inside the head. We report a computational study of the intensity and frequency of thermoelastic pressure waves generated by RF pulses in the human head inside high-field MRI and clinical scanners. The U.S. Food and Drug Administration (U.S. FDA) guides limit the local specific absorption rate (SAR) in the body-including the head-to 8 W kg(-1). We present results as functions of SAR and show that for a given SAR the peak acoustic pressures generated in the anatomic head model were essentially the same at 64, 300, and 400 MHz (1.5, 7.0, and 9.4 T). Pressures generated in the anatomic head are comparable to the threshold pressure of 20 mPa for sound perception by humans at the cochlea for 4 W kg(-1). Moreover, results indicate that the peak acoustic pressure in the brain is only 2 to 3 times the auditory threshold at the U.S. FDA guideline of 8 W kg(-1). Even at a high SAR of 20 W kg(-1), where the acoustic pressure in the brain could be more than 7 times the auditory threshold, the sound pressure levels would not be more than 17 db above threshold of perception at the cochlea.

  14. Studies of the interactions of an MRI system with the shielding in a combined PET/MRI scanner

    NASA Astrophysics Data System (ADS)

    Peng, Bo J.; Walton, Jeffrey H.; Cherry, Simon R.; Willig-Onwuachi, Jacob

    2010-01-01

    A positron emission tomography (PET) system or 'insert' has been constructed for placement and operation in the bore of a small animal magnetic resonance imaging (MRI) scanner to allow simultaneous MR and PET imaging. The insert contains electronics, components with a variety of magnetic properties and large continuous sheets of metal—all characteristics of an object that should, by conventional wisdom, never be placed in the bore of an MR scanner, especially near the imaging volume. There are a variety of ways the two systems might be expected to interact that could negatively impact the performance of either or both. In this article, the interaction mechanisms, particularly the impact of the PET insert and shielding on MR imaging, are defined and explored. Additionally, some of the difficulties in quantifying errors introduced into the MR images as a result of the presence of the PET components are demonstrated. Several different approaches are used to characterize image artifacts and determine optimal placement of the shielding. Data are also presented that suggest ways the shielding could be modified to reduce errors and enable placement closer to the isocenter of the magnet.

  15. Feasibility study using MRI and two optical CT scanners for readout of polymer gel and PresageTM

    NASA Astrophysics Data System (ADS)

    Svensson, H.; Skyt, P. S.; Ceberg, S.; Doran, S.; Muren, L. P.; Balling, P.; Petersen, J. B. B.; Bäck, S. Å. J.

    2013-06-01

    The aim of this study was to compare the conventional combination of three-dimensional dosimeter (nPAG gel) and readout method (MRI) with other combinations of three-dimensional dosimeters (nPAG gel/PresageTM) and readout methods (optical CT scanners). In the first experiment, the dose readout of a gel irradiated with a four field-box technique was performed with both an Octopus IQ scanner and MRI. It was seen that the MRI readout agreed slightly better to the TPS. In another experiment, a gel and a PresageTM sample were irradiated with a VMAT field and read out using MRI and a fast laser scanner, respectively. A comparison between the TPS and the volumes revealed that the MRI/gel readout had closer resemblance to the TPS than the optical CT/PresageTM readout. There are clearly potential in the evaluated optical CT scanners, but more time has to be invested in the particular scanning scenario than was possible in this study.

  16. The registration of signals from the nuclei other than protons at 0.5 T MRI scanner

    NASA Astrophysics Data System (ADS)

    Anisimov, N.; Volkov, D.; Gulyaev, M.; Pavlova, O.; Pirogov, Yu

    2016-02-01

    The practical aspects of the adaptation of the medical MRI scanner for multinuclear applications are considered. Examples of high resolution NMR spectra for nuclei 19F, 31P, 23Na, 11B, 13C, 2H, and also NQR spectrum for 35Cl are given. Possibilities of MRI for nuclei 19F, 31P, 23Na, 11B are shown. Experiments on registration of signals 19F from the fluorocarbons injected in laboratory animals are described.

  17. In Situ Active Control of Noise in a 4-Tesla MRI Scanner

    PubMed Central

    Li, Mingfeng; Rudd, Brent; Lim, Teik C.; Lee, Jing-Huei

    2011-01-01

    Purpose To evaluate the effectiveness of the proposed active noise control (ANC) system for the reduction of the acoustic noise emission generated by a 4 T MRI scanner during operation and to assess the feasibility of developing an ANC device that can be deployed in situ. Materials and Methods Three typical scanning sequences, namely EPI (echo planar imaging), GEMS (gradient echo multi-slice) and MDEFT (Modified Driven Equilibrium Fourier Transform), were used for evaluating the performance of the ANC system, which was composed of a magnetic compatible headset and a multiple reference feedforward filtered-x least mean square controller. Results The greatest reduction, about 55 dB, was achieved at the harmonic at a frequency of 1.3 kHz in the GEMS case. Approximately 21 dB and 30 dBA overall reduction was achieved for GEMS noise across the entire audible frequency range. For the MDEFT sequence, the control system achieved 14 dB and 14 dBA overall reduction in the audible frequency range, while 13 dB and 14 dBA reduction was obtained for the EPI case. Conclusion The result is highly encouraging because it shows great potential for treating MRI noise with an ANC application during real time scanning. PMID:21751284

  18. Implementation of fast macromolecular proton fraction mapping on 1.5 and 3 Tesla clinical MRI scanners: preliminary experience

    NASA Astrophysics Data System (ADS)

    Yarnykh, V.; Korostyshevskaya, A.

    2017-08-01

    Macromolecular proton fraction (MPF) is a biophysical parameter describing the amount of macromolecular protons involved into magnetization exchange with water protons in tissues. MPF represents a significant interest as a magnetic resonance imaging (MRI) biomarker of myelin for clinical applications. A recent fast MPF mapping method enabled clinical translation of MPF measurements due to time-efficient acquisition based on the single-point constrained fit algorithm. However, previous MPF mapping applications utilized only 3 Tesla MRI scanners and modified pulse sequences, which are not commonly available. This study aimed to test the feasibility of MPF mapping implementation on a 1.5 Tesla clinical scanner using standard manufacturer’s sequences and compare the performance of this method between 1.5 and 3 Tesla scanners. MPF mapping was implemented on 1.5 and 3 Tesla MRI units of one manufacturer with either optimized custom-written or standard product pulse sequences. Whole-brain three-dimensional MPF maps obtained from a single volunteer were compared between field strengths and implementation options. MPF maps demonstrated similar quality at both field strengths. MPF values in segmented brain tissues and specific anatomic regions appeared in close agreement. This experiment demonstrates the feasibility of fast MPF mapping using standard sequences on 1.5 T and 3 T clinical scanners.

  19. Inner experience in the scanner: can high fidelity apprehensions of inner experience be integrated with fMRI?

    PubMed Central

    Kühn, Simone; Fernyhough, Charles; Alderson-Day, Benjamin; Hurlburt, Russell T.

    2014-01-01

    To provide full accounts of human experience and behavior, research in cognitive neuroscience must be linked to inner experience, but introspective reports of inner experience have often been found to be unreliable. The present case study aimed at providing proof of principle that introspection using one method, descriptive experience sampling (DES), can be reliably integrated with fMRI. A participant was trained in the DES method, followed by nine sessions of sampling within an MRI scanner. During moments where the DES interview revealed ongoing inner speaking, fMRI data reliably showed activation in classic speech processing areas including left inferior frontal gyrus. Further, the fMRI data validated the participant’s DES observations of the experiential distinction between inner speaking and innerly hearing her own voice. These results highlight the precision and validity of the DES method as a technique of exploring inner experience and the utility of combining such methods with fMRI. PMID:25538649

  20. Static field influences on transcranial magnetic stimulation: Considerations for TMS in the scanner environment

    PubMed Central

    Yau, Jeffrey M.; Jalinous, Reza; Cantarero, Gabriela L.; Desmond, John E.

    2014-01-01

    Background: Transcranial magnetic stimulation (TMS) can be combined with functional magnetic resonance imaging (fMRI) to simultaneously manipulate and monitor human cortical responses. Although tremendous efforts have been directed at characterizing the impact of TMS on image acquisition, the influence of the scanner’s static field on the TMS coil has received limited attention. Objective/Hypothesis: The aim of this study was to characterize the influence of the scanner’s static field on TMS. We hypothesized that spatial variations in the static field could account for TMS field variations in the scanner environment. Methods: Using a MRI-compatible TMS coil, we estimated TMS field strengths based on TMS-induced voltage changes measured in a search coil. We compared peak field strengths obtained with the TMS coil positioned at different locations (B0 field vs fringe field) and orientations in the static field. We also measured the scanner’s static field to derive a field map to account for TMS field variations. Results: TMS field strength scaled depending on coil location and orientation with respect to the static field. Larger TMS field variations were observed in fringe field regions near the gantry as compared to regions inside the bore or further removed from the bore. The scanner’s static field also exhibited the greatest spatial variations in fringe field regions near the gantry. Conclusions: The scanner’s static field influences TMS fields and spatial variations in the static field correlate with TMS field variations. TMS field variations can be minimized by delivering TMS in the bore or outside of the 0 - 70 cm region from the bore entrance. PMID:24656916

  1. Human brain diffusion tensor imaging at submillimeter isotropic resolution on a 3Tesla clinical MRI scanner.

    PubMed

    Chang, Hing-Chiu; Sundman, Mark; Petit, Laurent; Guhaniyogi, Shayan; Chu, Mei-Lan; Petty, Christopher; Song, Allen W; Chen, Nan-kuei

    2015-09-01

    The advantages of high-resolution diffusion tensor imaging (DTI) have been demonstrated in a recent post-mortem human brain study (Miller et al., NeuroImage 2011;57(1):167-181), showing that white matter fiber tracts can be much more accurately detected in data at a submillimeter isotropic resolution. To our knowledge, in vivo human brain DTI at a submillimeter isotropic resolution has not been routinely achieved yet because of the difficulty in simultaneously achieving high resolution and high signal-to-noise ratio (SNR) in DTI scans. Here we report a 3D multi-slab interleaved EPI acquisition integrated with multiplexed sensitivity encoded (MUSE) reconstruction, to achieve high-quality, high-SNR and submillimeter isotropic resolution (0.85×0.85×0.85mm(3)) in vivo human brain DTI on a 3Tesla clinical MRI scanner. In agreement with the previously reported post-mortem human brain DTI study, our in vivo data show that the structural connectivity networks of human brains can be mapped more accurately and completely with high-resolution DTI as compared with conventional DTI (e.g., 2×2×2mm(3)).

  2. Numerical evaluation of E-fields induced by body motion near high-field MRI scanner.

    PubMed

    Crozier, S; Liu, F

    2004-01-01

    In modern magnetic resonance imaging (MRI), both patients and radiologists are exposed to strong, nonuniform static magnetic fields inside or outside of the scanner, in which the body movement may be able to induce electric currents in tissues which could be possibly harmful. This paper presents theoretical investigations into the spatial distribution of induced E-fields in the human model when moving at various positions around the magnet. The numerical calculations are based on an efficient, quasistatic, finite-difference scheme and an anatomically realistic, full-body, male model. 3D field profiles from an actively-shielded 4 T magnet system are used and the body model projected through the field profile with normalized velocity. The simulation shows that it is possible to induce E-fields/currents near the level of physiological significance under some circumstances and provides insight into the spatial characteristics of the induced fields. The results are easy to extrapolate to very high field strengths for the safety evaluation at a variety of field strengths and motion velocities.

  3. Corticospinal Tract Tracing in the Marmoset with a Clinical Whole-Body 3T Scanner Using Manganese-Enhanced MRI.

    PubMed

    Demain, Boris; Davoust, Carole; Plas, Benjamin; Bolan, Faye; Boulanouar, Kader; Renaud, Luc; Darmana, Robert; Vaysse, Laurence; Vieu, Christophe; Loubinoux, Isabelle

    2015-01-01

    Manganese-enhanced MRI (MEMRI) has been described as a powerful tool to depict the architecture of neuronal circuits. In this study we investigated the potential use of in vivo MRI detection of manganese for tracing neuronal projections from the primary motor cortex (M1) in healthy marmosets (Callithrix Jacchus). We determined the optimal dose of manganese chloride (MnCl2) among 800, 400, 40 and 8 nmol that led to manganese-induced hyperintensity furthest from the injection site, as specific to the corticospinal tract as possible, and that would not induce motor deficit. A commonly available 3T human clinical MRI scanner and human knee coil were used to follow hyperintensity in the corticospinal tract 24h after injection. A statistical parametric map of seven marmosets injected with the chosen dose, 8 nmol, showed the corticospinal tract and M1 connectivity with the basal ganglia, substantia nigra and thalamus. Safety was determined for the lowest dose that did not induce dexterity and grip strength deficit, and no behavioral effects could be seen in marmosets who received multiple injections of manganese one month apart. In conclusion, our study shows for the first time in marmosets, a reliable and reproducible way to perform longitudinal ME-MRI experiments to observe the integrity of the marmoset corticospinal tract on a clinical 3T MRI scanner.

  4. Corticospinal Tract Tracing in the Marmoset with a Clinical Whole-Body 3T Scanner Using Manganese-Enhanced MRI

    PubMed Central

    Plas, Benjamin; Bolan, Faye; Boulanouar, Kader; Renaud, Luc; Darmana, Robert; Vaysse, Laurence; Vieu, Christophe; Loubinoux, Isabelle

    2015-01-01

    Manganese-enhanced MRI (MEMRI) has been described as a powerful tool to depict the architecture of neuronal circuits. In this study we investigated the potential use of in vivo MRI detection of manganese for tracing neuronal projections from the primary motor cortex (M1) in healthy marmosets (Callithrix Jacchus). We determined the optimal dose of manganese chloride (MnCl2) among 800, 400, 40 and 8nmol that led to manganese-induced hyperintensity furthest from the injection site, as specific to the corticospinal tract as possible, and that would not induce motor deficit. A commonly available 3T human clinical MRI scanner and human knee coil were used to follow hyperintensity in the corticospinal tract 24h after injection. A statistical parametric map of seven marmosets injected with the chosen dose, 8 nmol, showed the corticospinal tract and M1 connectivity with the basal ganglia, substantia nigra and thalamus. Safety was determined for the lowest dose that did not induce dexterity and grip strength deficit, and no behavioral effects could be seen in marmosets who received multiple injections of manganese one month apart. In conclusion, our study shows for the first time in marmosets, a reliable and reproducible way to perform longitudinal ME-MRI experiments to observe the integrity of the marmoset corticospinal tract on a clinical 3T MRI scanner. PMID:26398500

  5. Superparamagnetic MRI probes for in vivo tracking of dendritic cell migration with a clinical 3 T scanner.

    PubMed

    Xu, Ye; Wu, Changqiang; Zhu, Wencheng; Xia, Chunchao; Wang, Dan; Zhang, Houbin; Wu, Jun; Lin, Gan; Wu, Bing; Gong, Qiyong; Song, Bin; Ai, Hua

    2015-07-01

    Dendritic cell (DC) based vaccines have shown promising results in the immunotherapy of cancers and other diseases. How to track the in vivo fate of DC vaccines will provide important insights to the final therapeutic results. In this study, we chose magnetic resonance imaging (MRI) to track murine DCs migration to the draining lymph node under a clinical 3 T scanner. Different from labeling immature DCs usually reported in literature, this study instead labeled matured DC with superparamagnetic iron oxide (SPIO) nanoparticle based imaging probes. The labeling process did not show negative impacts on cell viability, morphology, and surface biomarker expression. To overcome the imaging challenges brought by the limitations of the scanner, the size of lymph node, and the number of labeled cell, we optimized MRI pulse sequences. As a result, the signal reduction, caused either by gelatin phantoms containing as low as 12 SPIO-laden cells in each voxel or by the homing SPIO-laden DCs within the draining nodes after footpad injection of only 1 × 10(5) cells, can be clearly depicted under a 3 T MR scanner. Overall, the MRI labeling probes offer a low-toxic and high-efficient MR imaging platform for the assessment of DC-based immunotherapies.

  6. Burns from ECG leads in an MRI scanner: Case series and discussion of mechanisms

    PubMed Central

    Abdel-Rehim, S.; Bagirathan, S.; Al-Benna, S.; O’Boyle, C.

    2014-01-01

    Summary Iatrogenic burns are rare and preventable. The authors present two cases of burns from ECG leads, sustained during magnetic resonance imaging (MRI). Common features included a long duration spinal MR scan (120 and 60 minutes) and high patient body mass index (BMI >30). Both patients were discharged within 24 hours of admission, but required a period of outpatient burn care. The causation of these injuries remains unclear but there are several possible mechanisms including: electromagnetic induction heating, antenna effects and closed-loop current induction. The authors provide a description of the injuries, discuss possible mechanisms that may lead to burn injury in the MRI environment and suggest ways to reduce the risks of such injuries. PMID:26336370

  7. Burns from ECG leads in an MRI scanner: Case series and discussion of mechanisms.

    PubMed

    Abdel-Rehim, S; Bagirathan, S; Al-Benna, S; O'Boyle, C

    2014-12-31

    Iatrogenic burns are rare and preventable. The authors present two cases of burns from ECG leads, sustained during magnetic resonance imaging (MRI). Common features included a long duration spinal MR scan (120 and 60 minutes) and high patient body mass index (BMI >30). Both patients were discharged within 24 hours of admission, but required a period of outpatient burn care. The causation of these injuries remains unclear but there are several possible mechanisms including: electromagnetic induction heating, antenna effects and closed-loop current induction. The authors provide a description of the injuries, discuss possible mechanisms that may lead to burn injury in the MRI environment and suggest ways to reduce the risks of such injuries.

  8. Occupational exposure of healthcare and research staff to static magnetic stray fields from 1.5–7 Tesla MRI scanners is associated with reporting of transient symptoms

    PubMed Central

    Schaap, Kristel; Christopher-de Vries, Yvette; Mason, Catherine K; de Vocht, Frank; Portengen, Lützen; Kromhout, Hans

    2014-01-01

    Objectives Limited data is available about incidence of acute transient symptoms associated with occupational exposure to static magnetic stray fields from MRI scanners. We aimed to assess the incidence of these symptoms among healthcare and research staff working with MRI scanners, and their association with static magnetic field exposure. Methods We performed an observational study among 361 employees of 14 clinical and research MRI facilities in The Netherlands. Each participant completed a diary during one or more work shifts inside and/or outside the MRI facility, reporting work activities and symptoms (from a list of potentially MRI-related symptoms, complemented with unrelated symptoms) experienced during a working day. We analysed 633 diaries. Exposure categories were defined by strength and type of MRI scanner, using non-MRI shifts as the reference category for statistical analysis. Non-MRI shifts originated from MRI staff who also participated on MRI days, as well as CT radiographers who never worked with MRI. Results Varying per exposure category, symptoms were reported during 16–39% of the MRI work shifts. We observed a positive association between scanner strength and reported symptoms among healthcare and research staff working with closed-bore MRI scanners of 1.5 Tesla (T) and higher (1.5 T OR=1.88; 3.0 T OR=2.14; 7.0 T OR=4.17). This finding was mainly driven by reporting of vertigo and metallic taste. Conclusions The results suggest an exposure-response association between exposure to strong static magnetic fields (and associated motion-induced time-varying magnetic fields) and reporting of transient symptoms on the same day of exposure. Trial registration number 11-032/C PMID:24714654

  9. Spatial distortion correction and crystal identification for MRI-compatible position-sensitive avalanche photodiode-based PET scanners.

    PubMed

    Chaudhari, Abhijit J; Joshi, Anand A; Wu, Yibao; Leahy, Richard M; Cherry, Simon R; Badawi, Ramsey D

    2009-06-01

    Position-sensitive avalanche photodiodes (PSAPDs) are gaining widespread acceptance in modern PET scanner designs, and owing to their relative insensitivity to magnetic fields, especially in those that are MRI-compatible. Flood histograms in PET scanners are used to determine the crystal of annihilation photon interaction and hence, for detector characterization and routine quality control. For PET detectors that use PSAPDs, flood histograms show a characteristic pincushion distortion when Anger logic is used for event positioning. A small rotation in the flood histogram is also observed when the detectors are placed in a magnetic field. We first present a general purpose automatic method for spatial distortion correction for flood histograms of PSAPD-based PET detectors when placed both inside and outside a MRI scanner. Analytical formulae derived for this scheme are based on a hybrid approach that combines desirable properties from two existing event positioning schemes. The rotation of the flood histogram due to the magnetic field is determined iteratively and is accounted for in the scheme. We then provide implementation details of a method for crystal identification we have previously proposed and evaluate it for cases when the PET detectors are both outside and in a magnetic field. In this scheme, Fourier analysis is used to generate a lower-order spatial approximation of the distortion-corrected PSAPD flood histogram, which we call the 'template'. The template is then registered to the flood histogram using a diffeomorphic iterative intensity-based warping scheme. The calculated deformation field is then applied to the segmentation of the template to obtain a segmentation of the flood histogram. A manual correction tool is also developed for exceptional cases. We present a quantitative assessment of the proposed distortion correction scheme and crystal identification method against conventional methods. Our results indicate that our proposed methods lead to

  10. Comparison of 1.5T and 3T MRI scanners in evaluation of acute bone stress in the foot.

    PubMed

    Sormaala, Markus J; Ruohola, Juha-Petri; Mattila, Ville M; Koskinen, Seppo K; Pihlajamäki, Harri K

    2011-06-06

    Bone stress injuries are common in athletes and military recruits. Only a minority of bone stress changes are available on plain radiographs. Acute bone stress is often visible on MRI as bone marrow edema, which is also seen in many other disease processes such as malignancies, inflammatory conditions and infections. The purpose of this study was to investigate the ability of radiographs, 1.5T and 3T MRI to identify acute bone marrow changes in the foot. Ten patients with 12 stress fractures seen on plain radiographs underwent MRI using 1.5T and 3T scanners. T1 FSE and STIR axial, sagittal, and coronal view sequences were obtained. Two musculoskeletal radiologists interpreted the images independently and by consensus in case of disagreement. Of the 63 acute bone stress changes seen on 3T images, 61 were also seen on 1.5T images. The sensitivity of 1.5T MRI was 97% (95% CI: 89%-99%) compared with 3T. The 3T MRI images where, therefore, at least equally sensitive to 1.5T scanners in detection of bone marrow edema. On T1-weighted sequences, 3T images were slightly superior to 1.5T images in visualizing the demarcation of the edema and bone trabeculae. The kappa-value for inter-observer variability was 0.86 in the MRI indicating substantial interobserver agreement. Owing to slightly better resolution of 3T images, edema characterization is easier, which might aid in the differential diagnosis of the bone marrow edema. There was, however, no noteworthy difference in the sensitivity of the 1.5T and 3T images to bone marrow edema. Routine identification of acute bone stress changes and suspected stress injuries can, therefore, be made with 1.5T field strength.

  11. A cradle-shaped gradient coil to expand the clear-bore width of an animal MRI scanner.

    PubMed

    Gilbert, K M; Gati, J S; Klassen, L M; Menon, R S

    2010-01-21

    The never ending quest for higher magnetic field strengths in MRI and MRS has led to small and medium bore scanners at 9.4 T and above for both human and animal use; however, these bore diameters restrict the size of object that can be accommodated when using a conventional gradient coil. By replacing a cylindrical gradient-coil insert with a single-sided gradient coil, the scanner's functionality can be extended to include localized imaging of wider samples. As a prototype, a three-axis, cradle-shaped gradient coil was designed, fabricated and implemented in a 9.4 T animal MRI scanner. Since gradient fields are required only to be monotonic over the desired field of view, the cradle gradient coil was designed to produce high gradient efficiencies (up to 2.25 mT m(-1) A(-1) over a 5 cm imaging region) at the expense of gradient linearity. A dedicated three-dimensional algorithm was developed to correct the resultant image distortion. Preliminary images of a grid phantom and a mouse demonstrated the fidelity of the algorithm in correcting image distortion of greater than 200%. Eddy currents were measured along each gradient axis. A large 65.2 (Hz mT(-1) m) B(0) eddy current was produced by the y-axis, suggesting potential limitations of single-sided gradient coils.

  12. Computational dosimetry of induced electric fields during realistic movements in the vicinity of a 3 T MRI scanner

    NASA Astrophysics Data System (ADS)

    Laakso, Ilkka; Kännälä, Sami; Jokela, Kari

    2013-04-01

    Medical staff working near magnetic resonance imaging (MRI) scanners are exposed both to the static magnetic field itself and also to electric currents that are induced in the body when the body moves in the magnetic field. However, there are currently limited data available on the induced electric field for realistic movements. This study computationally investigates the movement induced electric fields for realistic movements in the magnetic field of a 3 T MRI scanner. The path of movement near the MRI scanner is based on magnetic field measurements using a coil sensor attached to a human volunteer. Utilizing realistic models for both the motion of the head and the magnetic field of the MRI scanner, the induced fields are computationally determined using the finite-element method for five high-resolution numerical anatomical models. The results show that the time-derivative of the magnetic flux density (dB/dt) is approximately linearly proportional to the induced electric field in the head, independent of the position of the head with respect to the magnet. This supports the use of dB/dt measurements for occupational exposure assessment. For the path of movement considered herein, the spatial maximum of the induced electric field is close to the basic restriction for the peripheral nervous system and exceeds the basic restriction for the central nervous system in the international guidelines. The 99th percentile electric field is a considerably less restrictive metric for the exposure than the spatial maximum electric field; the former is typically 60-70% lower than the latter. However, the 99th percentile electric field may exceed the basic restriction for dB/dt values that can be encountered during tasks commonly performed by MRI workers. It is also shown that the movement-induced eddy currents may reach magnitudes that could electrically stimulate the vestibular system, which could play a significant role in the generation of vertigo-like sensations reported

  13. Computational dosimetry of induced electric fields during realistic movements in the vicinity of a 3 T MRI scanner.

    PubMed

    Laakso, Ilkka; Kännälä, Sami; Jokela, Kari

    2013-04-21

    Medical staff working near magnetic resonance imaging (MRI) scanners are exposed both to the static magnetic field itself and also to electric currents that are induced in the body when the body moves in the magnetic field. However, there are currently limited data available on the induced electric field for realistic movements. This study computationally investigates the movement induced electric fields for realistic movements in the magnetic field of a 3 T MRI scanner. The path of movement near the MRI scanner is based on magnetic field measurements using a coil sensor attached to a human volunteer. Utilizing realistic models for both the motion of the head and the magnetic field of the MRI scanner, the induced fields are computationally determined using the finite-element method for five high-resolution numerical anatomical models. The results show that the time-derivative of the magnetic flux density (dB/dt) is approximately linearly proportional to the induced electric field in the head, independent of the position of the head with respect to the magnet. This supports the use of dB/dt measurements for occupational exposure assessment. For the path of movement considered herein, the spatial maximum of the induced electric field is close to the basic restriction for the peripheral nervous system and exceeds the basic restriction for the central nervous system in the international guidelines. The 99th percentile electric field is a considerably less restrictive metric for the exposure than the spatial maximum electric field; the former is typically 60-70% lower than the latter. However, the 99th percentile electric field may exceed the basic restriction for dB/dt values that can be encountered during tasks commonly performed by MRI workers. It is also shown that the movement-induced eddy currents may reach magnitudes that could electrically stimulate the vestibular system, which could play a significant role in the generation of vertigo-like sensations reported

  14. PET performance evaluation of MADPET4: a small animal PET insert for a 7-Tesla MRI scanner.

    PubMed

    Omidvari, Negar; Cabello, Jorge; Topping, Geoffrey; Schneider, Florian Roland; Paul, Stephan; Schwaiger, Markus; Ziegler, Sibylle I

    2017-10-04

    MADPET4 is the first small animal PET insert with two layers of individually read out crystals in combination with silicon photomultiplier technology. It has a novel detector arrangement, in which all crystals face the center of field of view transaxially. In this work, the PET performance of MADPET4 was evaluated and compared to other preclinical PET scanners using the NEMA NU 4 measurements, followed by imaging a mouse-size hot-rod resolution phantom and two in vivo simultaneous PET/MRI scans in a 7-T MRI scanner. The insert had a peak sensitivity of 0.49%, using an energy threshold of 350 keV. A uniform transaxial resolution was obtained up to 15 mm radial offset from the axial center, using filtered back-projection with single-slice rebinning. The measured average radial and tangential resolutions (FWHM) were 1.38 mm and 1.39 mm, respectively. The 1.2 mm rods were separable in the hot-rod phantom using an iterative image reconstruction algorithm. The scatter fraction was 7.3% and peak noise equivalent count rate was 15.5 kcps at 65.1 MBq of activity. The FDG uptake in a mouse heart and brain were visible in the two in vivo simultaneous PET/MRI scans without applying image corrections. In conclusion, the insert demonstrated a good overall performance and can be used for small animal multi-modal research applications. © 2017 Institute of Physics and Engineering in Medicine.

  15. Force and torque effects of a 1.5-Tesla MRI scanner on cardiac pacemakers and ICDs.

    PubMed

    Luechinger, R; Duru, F; Scheidegger, M B; Boesiger, P; Candinas, R

    2001-02-01

    Magnetic resonance imaging (MRI) is a widely accepted tool for the diagnosis of a variety of disease states. However, the presence of an implanted pacemaker is considered to be a strict contraindication to MRI in a vast majority of centers due to safety concerns. In phantom studies, the authors investigated the force and torque effects of the static magnetic field of MRI on pacemakers and ICDs. Thirty-one pacemakers (15 dual chamber and 16 single chamber units) from eight manufacturers and 13 ICDs from four manufacturers were exposed to the static magnetic field of a 1.5-Tesla MRI scanner. Magnetic force and acceleration measurements were obtained quantitatively, and torque measurements were made qualitatively. For pacemakers, the measured magnetic force was in the range of 0.05-3.60 N. Pacemakers released after 1995 had low magnetic force values as compared to the older devices. For these devices, the measured acceleration was even lower than the gravity of the earth (< 9.81 N/kg). Likewise, the torque levels were significantly reduced in newer generation pacemakers (< or = 2 from a scale of 6). ICD devices, except for one recent model, showed higher force (1.03-5.85 N), acceleration 9.5-34.2 N/kg), and torque (5-6 out of 6) levels. In conclusion, modern pacemakers present no safety risk with respect to magnetic force and torque induced by the static magnetic field of a 1.5-Tesla MRI scanner. However, ICD devices, despite considerable reduction in size and weight, may still pose problems due to strong magnetic force and torque.

  16. Commissioning of a new wide-bore MRI scanner for radiotherapy planning of head and neck cancer.

    PubMed

    Liney, G P; Owen, S C; Beaumont, A K E; Lazar, V R; Manton, D J; Beavis, A W

    2013-07-01

    A combination of CT and MRI is recommended for radiotherapy planning of head and neck cancers, and optimal spatial co-registration is achieved by imaging in the treatment position using the necessary immobilisation devices on both occasions, something which requires wide-bore scanners. Quality assurance experiments were carried out to commission a newly installed 1.5-T wide-bore MRI scanner and a dedicated, flexible six-channel phased array head and neck coil. Signal-to-noise ratio (SNR) and spatial signal uniformity were quantified using a homogeneous aqueous phantom, and geometric distortion was quantified using a phantom with water-filled fiducials in a grid pattern. Volunteer scans were also used to determine the in vivo image quality. Clinically relevant T1 weighted and T2 weighted fat-suppressed sequences were assessed in multiple scan planes (both sequences fast spin echo based). The performance of two online signal uniformity correction schemes, one utilising low-resolution reference scans and the other not utilising low-resolution reference scans, was compared. Geometric distortions, for a ±35-kHz bandwidth, were <1 mm for locations within 10 cm of the isocentre rising to 1.8 mm at 18 cm away. SNR was above 50, and uniformity in the axial plane was 71% and 95% before and after uniformity correction, respectively. The combined performance of the wide-bore scanner and the dedicated coil was adjudged adequate, although superior-inferior spatial coverage was slightly limited in the lower neck. These results will be of interest to the increasing number of oncology centres that are seeking to incorporate MRI into planning practice using dedicated equipment.

  17. Integrating a 1.5 T MRI scanner with a 6 MV accelerator: proof of concept.

    PubMed

    Raaymakers, B W; Lagendijk, J J W; Overweg, J; Kok, J G M; Raaijmakers, A J E; Kerkhof, E M; van der Put, R W; Meijsing, I; Crijns, S P M; Benedosso, F; van Vulpen, M; de Graaff, C H W; Allen, J; Brown, K J

    2009-06-21

    At the UMC Utrecht, The Netherlands, we have constructed a prototype MRI accelerator. The prototype is a modified 6 MV Elekta (Crawley, UK) accelerator next to a modified 1.5 T Philips Achieva (Best, The Netherlands) MRI system. From the initial design onwards, modifications to both systems were aimed to yield simultaneous and unhampered operation of the MRI and the accelerator. Indeed, the simultaneous operation is shown by performing diagnostic quality 1.5 T MRI with the radiation beam on. No degradation of the performance of either system was found. The integrated 1.5 T MRI system and radiotherapy accelerator allow simultaneous irradiation and MR imaging. The full diagnostic imaging capacities of the MRI can be used; dedicated sequences for MRI-guided radiotherapy treatments will be developed. This proof of concept opens the door towards a clinical prototype to start testing MRI-guided radiation therapy (MRIgRT) in the clinic.

  18. Spatial distortion correction and crystal identification for MRI-compatible position-sensitive avalanche photodiode-based PET scanners

    PubMed Central

    Chaudhari, Abhijit J.; Joshi, Anand A.; Wu, Yibao; Leahy, Richard M.; Cherry, Simon R.; Badawi, Ramsey D.

    2009-01-01

    Position-sensitive avalanche photodiodes (PSAPDs) are gaining widespread acceptance in modern PET scanner designs, and owing to their relative insensitivity to magnetic fields, especially in those that are MRI-compatible. Flood histograms in PET scanners are used to determine the crystal of annihilation photon interaction and hence, for detector characterization and routine quality control. For PET detectors that use PSAPDs, flood histograms show a characteristic pincushion distortion when Anger logic is used for event positioning. A small rotation in the flood histogram is also observed when the detectors are placed in a magnetic field. We first present a general purpose automatic method for spatial distortion correction for flood histograms of PSAPD-based PET detectors when placed both inside and outside a MRI scanner. Analytical formulae derived for this scheme are based on a hybrid approach that combines desirable properties from two existing event positioning schemes. The rotation of the flood histogram due to the magnetic field is determined iteratively and is accounted for in the scheme. We then provide implementation details of a method for crystal identification we have previously proposed and evaluate it for cases when the PET detectors are both outside and in a magnetic field. In this scheme, Fourier analysis is used to generate a lower-order spatial approximation of the distortion-corrected PSAPD flood histogram, which we call the ‘template’. The template is then registered to the flood histogram using a diffeomorphic iterative intensity-based warping scheme. The calculated deformation field is then applied to the segmentation of the template to obtain a segmentation of the flood histogram. A manual correction tool is also developed for exceptional cases. We present a quantitative assessment of the proposed distortion correction scheme and crystal identification method against conventional methods. Our results indicate that our proposed methods lead

  19. [Prospects of the use of mobile MRI scanner in medical service of the Armed Forces].

    PubMed

    Troyan, V N; Dydykin, A V; Rikun, A O; Filisteev, P A; Zayats, V V; Zhigalov, A A

    2015-10-01

    Computed tomography is currently one of the most informative methods of diagnostics of a broad range of injuries and diseases, as well as an effective additional mean for various surgical interventions thank to intraoperative use. In this regard, the question of the necessity of the use of this diagnostic technology in mobile hospitals is one of the current tasks. The article analyses the experience of the use of mobile CT scanners at the medical service of the armed forces of foreign states and provides calculations indicating the necessity of the introduction of mobile CT scanners into the hospital link. The review and classification of mobile CT scanners have allowed to formulate technical requirements for their hardware capabilities, as well as to draw conclusions about the conditions of their effective use.

  20. Experimental MRI-SPECT insert system with Hybrid Semiconductor detectors Timepix for MR animal scanner Bruker 47/20

    NASA Astrophysics Data System (ADS)

    Zajicek, J.; Burian, M.; Soukup, P.; Novak, V.; Macko, M.; Jakubek, J.

    2017-01-01

    Multimodal medical imaging based on Magnetic Resonance is mainly combinated with one of the scintigraphic method like PET or SPECT. These methods provide functional information whereas magnetic resonance imaging provides high spatial resolution of anatomical information or complementary functional information. Fusion of imaging modalities allows researchers to obtain complimentary information in a single measurement. The combination of MRI with SPECT is still relatively new and challenging in many ways. The main complication of using SPECT in MRI systems is the presence of a high magnetic field therefore (ferro)magnetic materials have to be eliminated. Furthermore the application of radiofrequency fields within the MR gantry does not allow for the use of conductive structures such as the common heavy metal collimators. This work presents design and construction of an experimental MRI-SPECT insert system and its initial tests. This unique insert system consists of an MR-compatible SPECT setup with CdTe pixelated sensors Timepix tungsten collimators and a radiofrequency coil. Measurements were performed on a gelatine and tissue phantom with an embedded radioisotopic source (57Co 122 keV γ ray) inside the RF coil by the Bruker BioSpec 47/20 (4.7 T) MR animal scanner. The project was performed in the framework of the Medipix Collaboration.

  1. Virtual MRI: a PC-based simulation of a clinical MR scanner.

    PubMed

    Hackländer, Thomas; Mertens, Heinrich

    2005-01-01

    The aim of this project was to simulate the features and functions of a clinical or real-world MR scanner on a personal computer by means of a computer program. The users should be able to change all relevant settings of the virtual scanner and adapt them to the expected pathology. The algorithms of the simulation are based on parameter images of the three physical basic properties T1, T2, and proton density. From this, the synthetic images are calculated pixel by pixel on the basis of the well-known formulas of the pulse sequences chosen and modified by the user. The graphical user interface is oriented to a real-world MR scanner. The software is programmed in pure Java and is freely available under the GPL license. Besides spin echo pulse sequence, 6 other pulse sequence classes are implemented. Parameters like repetition time and echo time can be adjusted. The choice of parameters like matrix size, slice-thickness, and number of acquisitions has an impact on the signal-to-noise ratio of the images. In a first step, the simulation calculates the signal intensity in k-space. Wraparound and motion artifacts are simulated by modifying the data of k-space. In a last step, a 2D-Fourier transform of k-space data is performed. As the image calculation takes only a few seconds, an interactive manner of working is possible. The simulation has been used in the education of medical students and interns for more than 1 year and has gained widespread acceptance.

  2. New shielding configurations for a simultaneous PET/MRI scanner at 7T.

    PubMed

    Peng, Bo J; Wu, Yibao; Cherry, Simon R; Walton, Jeffrey H

    2014-02-01

    Understanding sources of electromagnetic interference are important in designing any electronic system. This is especially true when combining positron emission tomography (PET) and magnetic resonance imaging (MRI) in a multimodality system as coupling between the subsystems can degrade the performance of either modality. For this reason, eliminating radio frequency (RF) interference and gradient-induced eddy currents have been major challenges in building simultaneous hybrid PET/MRI systems. MRI requires negligible RF interference at the Larmor resonance frequency, while RF interference at almost any frequency may corrupt PET data. Moreover, any scheme that minimizes these interactions would, ideally, not compromise the performance of either subsystem. This paper lays out a plan to resolve these problems. A carbon fiber composite material is found to be a good RF shield at the Larmor frequency (300MHz in this work) while introducing negligible gradient eddy currents. This carbon fiber composite also provides excellent structural support for the PET detector components. Low frequency electromagnetic radiation (81kHz here) from the switching power supplies of the gradient amplifiers was also found to interfere with the PET detector. Placing the PET detector module between two carbon fiber tubes and grounding the inner carbon fiber tube to the PET detector module ground reduced this interference. Further reductions were achieved by adding thin copper (Cu) foil on the outer carbon fiber case and electrically grounding the PET detector module so that all 3 components had a common ground, i.e. with the PET detector in an electrostatic cage. Finally, gradient switching typical in MRI sequences can result in count losses in the particular PET detector design studied. Moreover, the magnitude of this effect depends on the location of the detector within the magnet bore and which MRI gradient is being switched. These findings have a bearing on future designs of PET/MRI

  3. New shielding configurations for a simultaneous PET/MRI scanner at 7T

    PubMed Central

    Peng, Bo J.; Wu, Yibao; Cherry, Simon R.; Walton, Jeffrey H.

    2014-01-01

    Understanding sources of electromagnetic interference are important in designing any electronic system. This is especially true when combining positron emission tomography (PET) and magnetic resonance imaging (MRI) in a multimodality system as coupling between the subsystems can degrade the performance of either modality. For this reason, eliminating radio frequency (RF) interference and gradient-induced eddy currents have been major challenges in building simultaneous hybrid PET/MRI systems. MRI requires negligible RF interference at the Larmor resonance frequency, while RF interference at almost any frequency may corrupt PET data. Moreover, any scheme that minimizes these interactions would, ideally, not compromise the performance of either subsystem. This paper lays out a plan to resolve these problems. A carbon fiber composite material is found to be a good RF shield at the Larmor frequency (300 MHz in this work) while introducing negligible gradient eddy currents. This carbon fiber composite also provides excellent structural support for the PET detector components. Low frequency electromagnetic radiation (81 kHz here) from the switching power supplies of the gradient amplifiers was also found to interfere with the PET detector. Placing the PET detector module between two carbon fiber tubes and grounding the inner carbon fiber tube to the PET detector module ground reduced this interference. Further reductions were achieved by adding thin copper (Cu) foil on the outer carbon fiber case and electrically grounding the PET detector module so that all 3 components had a common ground, i.e. with the PET detector in an electrostatic cage. Finally, gradient switching typical in MRI sequences can result in count losses in the particular PET detector design studied. Moreover, the magnitude of this effect depends on the location of the detector within the magnet bore and which MRI gradient is being switched. These findings have a bearing on future designs of PET/MRI

  4. Game controller modification for fMRI hyperscanning experiments in a cooperative virtual reality environment

    PubMed Central

    Trees, Jason; Snider, Joseph; Falahpour, Maryam; Guo, Nick; Lu, Kun; Johnson, Douglas C.; Poizner, Howard; Liu, Thomas T.

    2014-01-01

    Hyperscanning, an emerging technique in which data from multiple interacting subjects’ brains are simultaneously recorded, has become an increasingly popular way to address complex topics, such as “theory of mind.” However, most previous fMRI hyperscanning experiments have been limited to abstract social interactions (e.g. phone conversations). Our new method utilizes a virtual reality (VR) environment used for military training, Virtual Battlespace 2 (VBS2), to create realistic avatar-avatar interactions and cooperative tasks. To control the virtual avatar, subjects use a MRI compatible Playstation 3 game controller, modified by removing all extraneous metal components and replacing any necessary ones with 3D printed plastic models. Control of both scanners’ operation is initiated by a VBS2 plugin to sync scanner time to the known time within the VR environment. Our modifications include:•Modification of game controller to be MRI compatible.•Design of VBS2 virtual environment for cooperative interactions.•Syncing two MRI machines for simultaneous recording. PMID:26150964

  5. Evaluation of an independent linear model for acoustic noise on a conventional MRI scanner and implications for acoustic noise reduction.

    PubMed

    Wu, Ziyue; Kim, Yoon-Chul; Khoo, Michael C K; Nayak, Krishna S

    2014-04-01

    To evaluate an independent linear model for gradient acoustic noise on a conventional MRI scanner, and to explore implications for acoustic noise reduction in routine imaging. Acoustic noise generated from each physical gradient axis was modeled as the prescribed gradient waveform passed through a linear time-invariant system. Homogeneity and superposition properties were experimentally determined. We also developed a new method to correct relative time shifts between the measured impulse responses for different physical gradient axes. Model accuracy was determined by comparing predicted and measured sound using normalized energy difference. Transfer functions were also measured in subjects with different body habitus and at multiple microphone locations. Both superposition and homogeneity held for each physical gradient axis with errors less than 3%. When all gradients were on simultaneous sound prediction, error was reduced from 32% to 4% after time-shift correction. Transfer functions also showed high sensitivity to body habitus and microphone location. The independent linear model predicts MRI acoustic noise with less than 4% error. Acoustic transfer functions are highly sensitive to body habitus and position within the bore, making it challenging to produce a general approach to acoustic noise reduction based on avoiding system resonance peaks. Copyright © 2013 Wiley Periodicals, Inc.

  6. A fast multiparameter MRI approach for acute stroke assessment on a 3T clinical scanner: preliminary results in a non-human primate model with transient ischemic occlusion

    PubMed Central

    Tong, Frank; Li, Chun-Xia; Yan, Yumei; Nair, Govind; Nagaoka, Tsukasa; Tanaka, Yoji; Zola, Stuart; Howell, Leonard

    2014-01-01

    Many MRI parameters have been explored and demonstrated the capability or potential to evaluate acute stroke injury, providing anatomical, microstructural, functional, or neurochemical information for diagnostic purposes and therapeutic development. However, the application of multiparameter MRI approach is hindered in clinic due to the very limited time window after stroke insult. Parallel imaging technique can accelerate MRI data acquisition dramatically and has been incorporated in modern clinical scanners and increasingly applied for various diagnostic purposes. In the present study, a fast multiparameter MRI approach including structural T1-weighted imaging (T1W), T2-weighted imaging (T2W), diffusion tensor imaging (DTI), T2-mapping, proton magnetic resonance spectroscopy, cerebral blood flow (CBF), and magnetization transfer (MT) imaging, was implemented and optimized for assessing acute stroke injury on a 3T clinical scanner. A macaque model of transient ischemic stroke induced by a minimal interventional approach was utilized for evaluating the multiparameter MRI approach. The preliminary results indicate the surgical procedure successfully induced ischemic occlusion in the cortex and/or subcortex in adult macaque monkeys (n=4). Application of parallel imaging technique substantially reduced the scanning duration of most MRI data acquisitions, allowing for fast and repeated evaluation of acute stroke injury. Hence, the use of the multiparameter MRI approach with up to five quantitative measures can provide significant advantages in preclinical or clinical studies of stroke disease. PMID:24834423

  7. Development of a MPPC-based prototype gantry for future MRI-PET scanners

    NASA Astrophysics Data System (ADS)

    Kurei, Y.; Kataoka, J.; Kato, T.; Fujita, T.; Ohshima, T.; Taya, T.; Yamamoto, S.

    2014-12-01

    We have developed a high spatial resolution, compact Positron Emission Tomography (PET) module designed for small animals and intended for use in magnetic resonance imaging (MRI) systems. This module consists of large-area, 4 × 4 ch MPPC arrays (S11830-3344MF; Hamamatsu Photonics K.K.) optically coupled with Ce-doped (Lu,Y)2(SiO4)O (Ce:LYSO) scintillators fabricated into 16 × 16 matrices of 0.5 × 0.5 mm2 pixels. We set the temperature sensor (LM73CIMK-0; National Semiconductor Corp.) at the rear of the MPPC acceptance surface, and apply optimum voltage to maintain the gain. The eight MPPC-based PET modules and coincidence circuits were assembled into a gantry arranged in a ring 90 mm in diameter to form the MPPC-based PET system. We have developed two types PET gantry: one made of non-magnetic metal and the other made of acrylonitrile butadiene styrene (ABS) resins. The PET gantry was positioned around the RF coil of the 4.7 T MRI system. We took an image of a point }22Na source under fast spin echo (FSE) and gradient echo (GE), in order to measure the interference between the MPPC-based PET and MRI. The spatial resolution of PET imaging in a transaxial plane of about 1 mm (FWHM) was achieved in all cases. Operating with PET made of ABS has no effect on MR images, while operating with PET made of non-magnetic metal has a significant detrimental effect on MR images. This paper describes our quantitative evaluations of PET images and MR images, and presents a more advanced version of the gantry for future MRI/DOI-PET systems.

  8. Towards undistorted and noise-free speech in an MRI scanner: correlation subtraction followed by spectral noise gating.

    PubMed

    Inouye, Joshua M; Blemker, Silvia S; Inouye, David I

    2014-03-01

    Noise cancellation in an MRI environment is difficult due to the high noise levels that are in the spectral range of human speech. This paper describes a two-step method to cancel MRI noise that combines operations in both the time domain (correlation subtraction) and the frequency domain (spectral noise gating). The resulting filtered recording has a noise power suppression of over 100 dB, a significant improvement over previously described techniques on MRI noise cancellation. The distortion is lower and the noise suppression higher than using spectral noise gating in isolation. Implementation of this method will aid in detailed studies of speech in relation to vocal tract and velopharyngeal function.

  9. Quantification of AC electromagnetic tracking system accuracy in a CT scanner environment

    NASA Astrophysics Data System (ADS)

    Shen, Eric; Shechter, Guy; Kruecker, Jochen; Stanton, Douglas

    2007-03-01

    The purpose of this study was to quantify the effects of a computed tomography (CT) scanner environment on the positional accuracy of an AC electromagnetic tracking system, the second generation NDI Aurora. A three-axis positioning robot was used to move an electromagnetically tracked needle above the CT table throughout a 30cm by 30cm axial plane sampled in 2.5cm steps. The corresponding position data was captured from the Aurora and was registered to the positioning system data using a rigid body transformation minimizing the least squares L2-norm. Data was sampled at varying distances from the CT gantry (three feet, two feet, and one foot) and with the CT table in a nominal position and lowered by 10cm. A coordinate system was defined with the x axis normal to the CT table and the origin at the center of the CT table, and the z axis spanning the table in the lateral direction with the origin at the center of the CT table. In this coordinate system, the positional relationships of each sampled point, the CT table, and the Aurora field generator are clearly defined. This allows error maps to be displayed in accurate spatial relationship to the CT scanner as well as to a representative patient anatomy. By quantifying the distortions in relation to the position of CT scanner components and the Aurora field generator, the optimal working field of view and recommended guidelines for operation can be determined such that targeting inside human anatomy can be done with reasonable expectations of desired performance.

  10. An adaptive, individualized fMRI delay discounting procedure to increase flexibility and optimize scanner time.

    PubMed

    Koffarnus, Mikhail N; Deshpande, Harshawardhan U; Lisinski, Jonathan M; Eklund, Anders; Bickel, Warren K; LaConte, Stephen M

    2017-08-10

    Research on the rate at which people discount the value of future rewards has become increasingly prevalent as discount rate has been shown to be associated with many unhealthy patterns of behavior such as drug abuse, gambling, and overeating. fMRI research points to a fronto-parietal-limbic pathway that is active during decisions between smaller amounts of money now and larger amounts available after a delay. Researchers in this area have used different variants of delay discounting tasks and reported various contrasts between choice trials of different types from these tasks. For instance, researchers have compared 1) choices of delayed monetary amounts to choices of the immediate monetary amounts, 2) 'hard' choices made near one's point of indifference to 'easy' choices that require little thought, and 3) trials where an immediate choice is available versus trials where one is unavailable, regardless of actual eventual choice. These differences in procedure and analysis make comparison of results across studies difficult. In the present experiment, we designed a delay discounting task with the intended capability of being able to construct contrasts of all three comparisons listed above while optimizing scanning time to reduce costs and avoid participant fatigue. This was accomplished with an algorithm that customized the choice trials presented to each participant with the goal of equalizing choice trials of each type. We compared this task, which we refer to here as the individualized discounting task (IDT), to two other delay discounting tasks previously reported in the literature (McClure et al., 2004; Amlung et al., 2014) in 18 participants. Results show that the IDT can examine each of the three contrasts mentioned above, while yielding a similar degree of activation as the reference tasks. This suggests that this new task could be used in delay discounting fMRI studies to allow researchers to more easily compare their results to a majority of previous

  11. Talking about social conflict in the MRI scanner: neural correlates of being empathized with.

    PubMed

    Seehausen, Maria; Kazzer, Philipp; Bajbouj, Malek; Heekeren, Hauke R; Jacobs, Arthur M; Klann-Delius, Gisela; Menninghaus, Winfried; Prehn, Kristin

    2014-01-01

    This study investigated the emotional effects and neural correlates of being empathized with while speaking about a currently experienced real-life social conflict during fMRI. Specifically, we focused on the effects of cognitive empathy in the form of paraphrasing, a technique regularly used in conflict resolution. 22 participants underwent fMRI while being interviewed on their social conflict and receiving empathic or unempathic responses from the interviewer. Skin conductance response (SCR) and self-report ratings of feeling understood and emotional valence were used to assess emotional responses. Results confirm previous findings indicating that cognitive empathy exerts a positive short-term effect on emotions in social conflict, while at the same time increasing autonomic arousal reflected by SCR. Effects of paraphrasing and unempathic interventions as indicated by self-report ratings varied depending on self-esteem, pre-interview negative affect, and participants' empathy quotient. Empathic responses engaged a fronto-parietal network with activity in the right precentral gyrus (PrG), left middle frontal gyrus (MFG), left inferior parietal gyrus (IPG), and right postcentral gyrus (PoG). Processing unempathic responses involved a fronto-temporal network with clusters peaking in the left inferior frontal gyrus, pars triangularis (IFGTr), and right temporal pole (TP). A specific modeling of feeling misunderstood activated a network consisting of the IFG, left TP, left Heschl gyrus, IFGTr, and right precuneus, extending to several limbic regions, such as the insula, amygdala, putamen, and anterior cingulate cortex/right middle cingulum (ACC/MCC). The results support the effectiveness of a widely used conflict resolution technique, which may also be useful for professionals who regularly deal with and have to de-escalate situations highly charged with negative emotion, e.g. physicians or judges. © 2013 Elsevier Inc. All rights reserved.

  12. Combined MRI-PET scanner: A Monte Carlo evaluation of the improvements in PET resolution due to the effects of a static homogeneous magnetic field

    SciTech Connect

    Raylman, R.R.; Hammer, B.E.; Christensen, N.L.

    1996-08-01

    Positron emission tomography (PET) relies upon the detection of photons resulting from the annihilation of positrons emitted by a radiopharmaceutical. The combination of images obtained with PET and magnetic resonance imaging (MRI) have begun to greatly enhance the study of many physiological processes. A combined MRI-PET scanner could alleviate much of the spatial and temporal coregistration difficulties currently encountered in utilizing images from these complementary imaging modalities. In addition, the resolution of the PET scanner could be improved by the effects of the magnetic field. In this computer study, the utilization of a strong static homogeneous magnetic field to increase PET resolution by reducing the effects of positron range and photon noncollinearity was investigated. The results reveal that significant enhancement of resolution can be attained. For example, an approximately 27% increase in resolution is predicted for a PET scanner incorporating a 10-Tesla magnetic field. Most of this gain in resolution is due to magnetic confinement of the emitted positrons. Although the magnetic field does mix some positronium states resulting in slightly less photon noncollinearity, this reduction does not significantly affect resolution. Photon noncollinearity remains as the fundamental limiting factor of large PET scanner resolution.

  13. MR-guided percutaneous biopsy of solitary pulmonary lesions using a 1.0-T open high-field MRI scanner with respiratory gating.

    PubMed

    Liu, Ming; Huang, Jie; Xu, Yujun; He, Xiangmeng; Li, Lei; Lü, Yubo; Liu, Qiang; Sequeiros, Roberto Blanco; Li, Chengli

    2017-04-01

    To prospectively evaluate the feasibility, safety and accuracy of MR-guided percutaneous biopsy of solitary pulmonary lesions using a 1.0-T open MR scanner with respiratory gating. Sixty-five patients with 65 solitary pulmonary lesions underwent MR-guided percutaneous coaxial cutting needle biopsy using a 1.0-T open MR scanner with respiratory gating. Lesions were divided into two groups according to maximum lesion diameters: ≤2.0 cm (n = 31) and >2.0 cm (n = 34). The final diagnosis was established in surgery and subsequent histology. Diagnostic accuracy, sensitivity and specificity were compared between the groups using Fisher's exact test. Accuracy, sensitivity and specificity of MRI-guided percutaneous pulmonary biopsy in diagnosing malignancy were 96.9 %, 96.4 % and 100 %, respectively. Accuracy, sensitivity and specificity were 96.8 %, 96.3 % and 100 % for lesions 2.0 cm or smaller and 97.1 %, 96.4 % and 100 %, respectively, for lesions larger than 2.0 cm. There was no significant difference between the two groups (P > 0.05). Biopsy-induced complications encountered were pneumothorax in 12.3 % (8/65) and haemoptysis in 4.6 % (3/65). There were no serious complications. MRI-guided percutaneous biopsy using a 1.0-T open MR scanner with respiratory gating is an accurate and safe diagnostic technique in evaluation of pulmonary lesions. • MRI-guided percutaneous lung biopsy using a 1.0-T open MR scanner is feasibility. • 96.9 % differentiation accuracy of malignant and benign lung lesions is possible. • No serious complications occurred in MRI-guided lung biopsy.

  14. A job interview in the MRI scanner: How does indirectness affect addressees and overhearers?

    PubMed

    Bašnáková, Jana; van Berkum, Jos; Weber, Kirsten; Hagoort, Peter

    2015-09-01

    In using language, people not only exchange information, but also navigate their social world - for example, they can express themselves indirectly to avoid losing face. In this functional magnetic resonance imaging study, we investigated the neural correlates of interpreting face-saving indirect replies, in a situation where participants only overheard the replies as part of a conversation between two other people, as well as in a situation where the participants were directly addressed themselves. We created a fictional job interview context where indirect replies serve as a natural communicative strategy to attenuate one's shortcomings, and asked fMRI participants to either pose scripted questions and receive answers from three putative job candidates (addressee condition) or to listen to someone else interview the same candidates (overhearer condition). In both cases, the need to evaluate the candidate ensured that participants had an active interest in comprehending the replies. Relative to direct replies, face-saving indirect replies increased activation in medial prefrontal cortex, bilateral temporo-parietal junction (TPJ), bilateral inferior frontal gyrus and bilateral middle temporal gyrus, in active overhearers and active addressees alike, with similar effect size, and comparable to findings obtained in an earlier passive listening study (Bašnáková et al., 2014). In contrast, indirectness effects in bilateral anterior insula and pregenual ACC, two regions implicated in emotional salience and empathy, were reliably stronger in addressees than in active overhearers. Our findings indicate that understanding face-saving indirect language requires additional cognitive perspective-taking and other discourse-relevant cognitive processing, to a comparable extent in active overhearers and addressees. Furthermore, they indicate that face-saving indirect language draws upon affective systems more in addressees than in overhearers, presumably because the addressee

  15. Exposure to static and time-varying magnetic fields from working in the static magnetic stray fields of MRI scanners: a comprehensive survey in the Netherlands.

    PubMed

    Schaap, Kristel; Christopher-De Vries, Yvette; Crozier, Stuart; De Vocht, Frank; Kromhout, Hans

    2014-11-01

    Clinical and research staff who work around magnetic resonance imaging (MRI) scanners are exposed to the static magnetic stray fields of these scanners. Although the past decade has seen strong developments in the assessment of occupational exposure to electromagnetic fields from MRI scanners, there is insufficient insight into the exposure variability that characterizes routine MRI work practice. However, this is an essential component of risk assessment and epidemiological studies. This paper describes the results of a measurement survey of shift-based personal exposure to static magnetic fields (SMF) (B) and motion-induced time-varying magnetic fields (dB/dt) among workers at 15 MRI facilities in the Netherlands. With the use of portable magnetic field dosimeters, >400 full-shift and partial shift exposure measurements were collected among various jobs involved in clinical and research MRI. Various full-shift exposure metrics for B and motion-induced dB/dt exposure were calculated from the measurements, including instantaneous peak exposure and time-weighted average (TWA) exposures. We found strong correlations between levels of static (B) and time-varying (dB/dt) exposure (r = 0.88-0.92) and between different metrics (i.e. peak exposure, TWA exposure) to express full-shift exposure (r = 0.69-0.78). On average, participants were exposed to MRI-related SMFs during only 3.7% of their work shift. Average and peak B and dB/dt exposure levels during the work inside the MRI scanner room were highest among technical staff, research staff, and radiographers. Average and peak B exposure levels were lowest among cleaners, while dB/dt levels were lowest among anaesthesiology staff. Although modest exposure variability between workplaces and occupations was observed, variation between individuals of the same occupation was substantial, especially among research staff. This relatively large variability between workers with the same job suggests that exposure classification

  16. Feasibility and Success Rate of a Fetal MRI and MR Spectroscopy Research Protocol Performed at Term Using a 3.0-Tesla Scanner.

    PubMed

    Sanz Cortes, Magdalena; Bargallo, Nuria; Arranz, Angela; Simoes, Rui; Figueras, Francesc; Gratacos, Eduard

    2017-01-01

    To report the feasibility and main factors affecting the success of a fetal magnetic resonance imaging (MRI) and MR spectroscopy (MRS) research protocol performed at term using a 3-tesla scanner. Pregnant patients at term underwent an MRI. Specific measures were taken to prevent maternal discomfort and distress, such as detailed counseling and maternal repositioning if needed. MRS data were acquired from the frontal lobe and basal ganglia, and processed applying quality control criteria. The mean gestational age at MRI was 37.4 ± 0.9 weeks. From a total of 245 patients that showed up for the MRI, 11 referred claustrophobia which prevented the test from starting, and 30 patients started the test but decided to discontinue due to discomfort. Thus, the examination was complete in 204 patients. MRS data could be obtained in 170 cases from the frontal lobe and 165 cases from the basal ganglia, of which 52.4 and 68.6%, respectively, complied with our defined quality criteria. The mean scanning time was 34:16 ± 9:30 min:s after excluding those cases presenting initial intolerance to the test. Minor abnormalities were described in 11 MRI reports. The fetal MRI/MRS protocol was feasible and generally well tolerated at term on a 3-tesla scanner, but a significant number of cases were lost to analysis. The rate of patients that eventually provided usable research information was 95.5% for anatomical examination and 52.4-68.6% for MRS. This information should be taken into account in the design of fetal brain MRI studies. © 2016 S. Karger AG, Basel.

  17. Building virtual reality fMRI paradigms: a framework for presenting immersive virtual environments.

    PubMed

    Mueller, Charles; Luehrs, Michael; Baecke, Sebastian; Adolf, Daniela; Luetzkendorf, Ralf; Luchtmann, Michael; Bernarding, Johannes

    2012-08-15

    The advantage of using a virtual reality (VR) paradigm in fMRI is the possibility to interact with highly realistic environments. This extends the functions of standard fMRI paradigms, where the volunteer usually has a passive role, for example, watching a simple movie paradigm without any stimulus interactions. From that point of view the combined usage of VR and real-time fMRI offers great potential to identify underlying cognitive mechanisms such as spatial navigation, attention, semantic and episodic memory, as well as neurofeedback paradigms. However, the design and the implementation of a VR stimulus paradigm as well as the integration into an existing MR scanner framework are very complex processes. To support the modeling and usage of VR stimuli we developed and implemented a VR stimulus application based on C++. This software allows the fast and easy presentation of VR environments for fMRI studies without any additional expert knowledge. Furthermore, it provides for the reception of real-time data analysis values a bidirectional communication interface. In addition, the internal plugin interface enables users to extend the functionality of the software with custom programmed C++ plugins. The VR stimulus framework was tested in several performance tests and a spatial navigation study. According to the post-experimental interview, all subjects described immersive experiences and a high attentional load inside the artifical environment. Results from other VR spatial memory studies confirm the neuronal activation that was detected in parahippocampal areas, cuneus, and occipital regions. Copyright © 2012 Elsevier B.V. All rights reserved.

  18. Reproducibility of pulmonary blood flow measurements by phase-contrast MRI using different 1.5 T MR scanners at two institutions

    PubMed Central

    Iraha, Rin; Tsuchiya, Nanae; Yamashiro, Tsuneo; Iwasawa, Tae

    2017-01-01

    Background Magnetic resonance imaging (MRI) can be beneficial for diagnosis of disease by offering quantitative information. However, reproducibility can be a major problem when there is a numerical threshold in multi-institution, multi-vendor situations. Purpose To measure pulmonary blood flow with phase-contrast (PC) imaging using two different MR scanners (1.5 T) at different institutions in the same participants and to examine the reproducibility of the measurements. Material and Methods Participants were 10 healthy volunteers (5 men; age range, 27–36 years). The measurements included the mean and maximal blood velocities, the mean blood flow volume, and the acceleration time and volume (AT and AV), derived from the time-flow curve of the PC-MRI. Simultaneously obtained maximal, minimal, and mean areas from regions of interest set in the pulmonary artery were also calculated. In order to calculate the reproducibility of the quantitative variables, intra-class correlation coefficients (ICCs) were employed. When an adequate ICC was obtained, Bland–Altman analysis was conducted to identify any systematic bias. Results The ICCs were almost perfect for the mean blood flow volume and the AV (r = 0.82 and 0.80), and were substantial in the mean and maximal areas, and the AT (r = 0.63, 0.74, and 0.64, respectively). However, there was a fixed bias in the area measurement between the two scanners. Also, the AV had a proportional bias. Conclusion Our results reveal that various indices derived from PC-MRI on different MR scanners are promising as common indices for pulmonary flow assessment. Research and clinical use of PC-MRI for the pulmonary artery is expected to extend to multi-institution situations. PMID:28210495

  19. Assessment of a Static Multibeam Sonar Scanner for 3d Surveying in Confined Subaquatic Environments

    NASA Astrophysics Data System (ADS)

    Moisan, E.; Charbonnier, P.; Foucher, P.; Grussenmeyer, P.; Guillemin, S.; Samat, O.; Pagès, C.

    2016-06-01

    Mechanical Scanning Sonar (MSS) is a promising technology for surveying underwater environments. Such devices are comprised of a multibeam echosounder attached to a pan & tilt positioner, that allows sweeping the scene in a similar way as Terrestrial Laser Scanners (TLS). In this paper, we report on the experimental assessment of a recent MSS, namely, the BlueView BV5000, in a confined environment: lock number 50 on the Marne-Rhin canal (France). To this aim, we hung the system upside-down to scan the lock chamber from the surface, which allows surveying the scanning positions, up to an horizontal orientation. We propose a geometric method to estimate the remaining angle and register the scans in a coordinate system attached to the site. After reviewing the different errors that impair sonar data, we compare the resulting point cloud to a TLS model that was acquired the day before, while the lock was completely empty for maintenance. While the results exhibit a bias that can be partly explained by an imperfect setup, the maximum difference is less than 15 cm, and the standard deviation is about 3.5 cm. Visual inspection shows that coarse defects of the masonry, such as stone lacks or cavities, can be detected in the MSS point cloud, while smaller details, e.g. damaged joints, are harder to notice.

  20. Cylindrical Scanner

    SciTech Connect

    Hall, Thomas E.

    1999-04-29

    The CS system is designed to provide a very fast imaging system in order to search for weapons on persons in an airport environment. The Cylindrical Scanner moves a vertical transceiver array rapidly around a person standing stationary. The software can be segmented in to three specific tasks. The first task is data acquisition and scanner control. At the operator's request, this task commands the scanner to move and the radar transceiver array to send data to the computer system in a known and well-ordered manner. The array is moved over the complete aperture in 10 to 12 seconds. At the completion of the array movement the second software task automatically reconstructs the high-resolution image from the radar data utilizing the integrated DSP boards. The third task displays the resulting images, as they become available, to the computer screen for user review and analysis.

  1. Gd-AAZTA-MADEC, an improved blood pool agent for DCE-MRI studies on mice on 1 T scanners.

    PubMed

    Longo, Dario Livio; Arena, Francesca; Consolino, Lorena; Minazzi, Paolo; Geninatti-Crich, Simonetta; Giovenzana, Giovanni Battista; Aime, Silvio

    2016-01-01

    A novel MRI blood-pool contrast agent (Gd-AAZTA-MADEC) has been compared with established blood pool agents for tumor contrast enhanced images and angiography. Synthesis, relaxometric properties, albumin binding affinity and pharmacokinetic profiles are reported. For in vivo studies, angiographic images and tumor contrast enhanced images were acquired on mice with benchtop 1T-MRI scanners and compared with MS-325, B22956/1 and B25716/1. The design of this contrast agent involved the elongation of the spacer between the targeting deoxycholic acid moiety and the Gd-AAZTA imaging reporting unit that drastically changed either the binding affinity to albumin (KA(HSA) = 8.3 × 10(5) M(-1)) and the hydration state of the Gd ion (q = 2) in comparison to the recently reported B25716/1. The very markedly high binding affinity towards mouse and human serum albumins resulted in peculiar pharmacokinetics and relaxometric properties. The NMRD profiles clearly indicated that maximum efficiency is attainable at magnetic field strength of 1 T. In vivo studies showed high enhancement of the vasculature and a prolonged accumulation inside tumor. The herein reported pre-clinical imaging studies show that a great benefit arises from the combination of a benchtop MRI scanner operating at 1 T and the albumin-binding Gd-AAZTA-MADEC complex, for pursuing enhanced angiography and improved characterization of tumor vascular microenvironment.

  2. Airborne laser scanner aided inertial for terrain referenced navigation in unknown environments

    NASA Astrophysics Data System (ADS)

    Vadlamani, Ananth Kalyan

    A dead-reckoning terrain referenced navigation (TRN) system that uses airborne laser ranging sensors to aid an aircraft inertial navigation system (INS) is presented. Improved navigation performance is achieved through estimation of vehicle velocity and position using terrain measurements. The system only uses aircraft sensors and simultaneously performs the dual functions of mapping and navigation in unknown environments. The theory, algorithms and results of the system performance are presented using simulations and flight test data. This dissertation focuses primarily on the use of dual airborne laser scanners (ALS) for aiding an INS. Dual ALS measurements are used to generate overlapping terrain models, which are then used to estimate the INS velocity and position errors and constrain its drift. By keeping track of its errors, a navigation-grade INS is aided in a feed-forward manner. This dead-reckoning navigation algorithm is generic enough to be easily extendable to use other optical sensors. Data integrity, sensor alignment and the effects of vegetation noise, attitude and heading accuracy are analyzed. Furthermore, a feedback coupled aiding scheme is presented in which a tactical-grade inertial measurement unit (IMU) is aided with dual ALS measurements by feeding the estimated velocity back into the IMU computations. The proposed system can potentially serve as a backup during temporary Global Positioning System (GPS) signal outages, or it can be used to coast for extended periods of time. Although it has elements of conventional TRN, this system does not require a terrain database since its in-flight mapping capability generates the terrain data for navigation. Hence, the system can be used in both non-GPS as well as unknown terrain environments. The navigation system is dead-reckoning in nature and errors accumulate over time, unless the system can be reset periodically by geo-referenced terrain data or a position estimate from another navigation aid.

  3. Real time speech enhancement for the noisy MRI environment.

    PubMed

    Pathak, Nishank; Panahi, Issa; Devineni, P; Briggs, Richard

    2009-01-01

    Performance of two Adaptive (nLMS and Normalized Sign-error LMS) and a single channel (LogMMSE) speech enhancement algorithms are tested on a floating point DSP to reveal their effectiveness in enhancing speech corrupted in noisy MRI environment with very low SNR. The purpose of experiments is to reduce the fatigue of the listener by eliminating the strong MRI noise. The experiments use actual data set collected from a 3-Tesla MRI machine. Results of the experiments and performance of the speech enhancement system are presented in this paper. The speech enhancement system is automated. Our experiments reveal that after enhancement of the speech signal using Sign-Error LMS, the residual noise shows characteristics of white noise in contrast to the residual noise of the other algorithms which is more structured. It is also shown that the Sign-Error LMS offers fast convergence in comparison to the other two methods.

  4. NOTE: Integrating a 1.5 T MRI scanner with a 6 MV accelerator: proof of concept

    NASA Astrophysics Data System (ADS)

    Raaymakers, B. W.; Lagendijk, J. J. W.; Overweg, J.; Kok, J. G. M.; Raaijmakers, A. J. E.; Kerkhof, E. M.; van der Put, R. W.; Meijsing, I.; Crijns, S. P. M.; Benedosso, F.; van Vulpen, M.; de Graaff, C. H. W.; Allen, J.; Brown, K. J.

    2009-06-01

    At the UMC Utrecht, The Netherlands, we have constructed a prototype MRI accelerator. The prototype is a modified 6 MV Elekta (Crawley, UK) accelerator next to a modified 1.5 T Philips Achieva (Best, The Netherlands) MRI system. From the initial design onwards, modifications to both systems were aimed to yield simultaneous and unhampered operation of the MRI and the accelerator. Indeed, the simultaneous operation is shown by performing diagnostic quality 1.5 T MRI with the radiation beam on. No degradation of the performance of either system was found. The integrated 1.5 T MRI system and radiotherapy accelerator allow simultaneous irradiation and MR imaging. The full diagnostic imaging capacities of the MRI can be used; dedicated sequences for MRI-guided radiotherapy treatments will be developed. This proof of concept opens the door towards a clinical prototype to start testing MRI-guided radiation therapy (MRIgRT) in the clinic.

  5. The use of a low-cost visible light 3D scanner to create virtual reality environment models of actors and objects

    NASA Astrophysics Data System (ADS)

    Straub, Jeremy

    2015-05-01

    A low-cost 3D scanner has been developed with a parts cost of approximately USD $5,000. This scanner uses visible light sensing to capture both structural as well as texture and color data of a subject. This paper discusses the use of this type of scanner to create 3D models for incorporation into a virtual reality environment. It describes the basic scanning process (which takes under a minute for a single scan), which can be repeated to collect multiple positions, if needed for actor model creation. The efficacy of visible light versus other scanner types is also discussed.

  6. Improving magnetic resonance imaging (MRI) examinations: Development and evaluation of an intervention to reduce movement in scanners and facilitate scan completion.

    PubMed

    Powell, Rachael; Ahmad, Mahadir; Gilbert, Fiona J; Brian, David; Johnston, Marie

    2015-09-01

    The movement of patients in magnetic resonance imaging (MRI) scanners results in motion artefacts which impair image quality. Non-completion of scans leads to delay in diagnosis and increased costs. This study aimed to develop and evaluate an intervention to enable patients to stay still in MRI scanners (reducing motion artefacts) and to enhance scan completion. Successful scan outcome was deemed to be completing the scan with no motion artefacts. Previous research indicated self-efficacy to predict successful scan outcome, and interviews with patients identified a need for procedural and sensory information to facilitate successful scan behaviour. A DVD intervention was developed which targeted self-efficacy and included procedural and sensory information. It was successfully piloted with 10 patients and then evaluated in a randomized controlled trial compared with the standard hospital information leaflet (intervention group N = 41; control group N = 42). The clinic radiographer, who was blind to group allocation, rated MRI scans for motion artefact and recorded whether the participant completed the scan; participants completed MRI self-efficacy and anxiety measures. Only one participant reported not finding the DVD useful. Thirty-five participants in the intervention group and 23 in the control group completed scans and had no motion artefacts, χ(2) (1, 83) = 7.84, p < .001 (relative risk of an unsatisfactory outcome in the control group/intervention group = 3.09). The intervention effect was mediated by self-efficacy. The DVD intervention was efficacious and warrants further research to examine generalizability. © 2015 The British Psychological Society.

  7. SU-F-R-08: Can Normalization of Brain MRI Texture Features Reduce Scanner-Dependent Effects in Unsupervised Machine Learning?

    SciTech Connect

    Ogden, K; O’Dwyer, R; Bradford, T; Cussen, L

    2016-06-15

    Purpose: To reduce differences in features calculated from MRI brain scans acquired at different field strengths with or without Gadolinium contrast. Methods: Brain scans were processed for 111 epilepsy patients to extract hippocampus and thalamus features. Scans were acquired on 1.5 T scanners with Gadolinium contrast (group A), 1.5T scanners without Gd (group B), and 3.0 T scanners without Gd (group C). A total of 72 features were extracted. Features were extracted from original scans and from scans where the image pixel values were rescaled to the mean of the hippocampi and thalami values. For each data set, cluster analysis was performed on the raw feature set and for feature sets with normalization (conversion to Z scores). Two methods of normalization were used: The first was over all values of a given feature, and the second by normalizing within the patient group membership. The clustering software was configured to produce 3 clusters. Group fractions in each cluster were calculated. Results: For features calculated from both the non-rescaled and rescaled data, cluster membership was identical for both the non-normalized and normalized data sets. Cluster 1 was comprised entirely of Group A data, Cluster 2 contained data from all three groups, and Cluster 3 contained data from only groups 1 and 2. For the categorically normalized data sets there was a more uniform distribution of group data in the three Clusters. A less pronounced effect was seen in the rescaled image data features. Conclusion: Image Rescaling and feature renormalization can have a significant effect on the results of clustering analysis. These effects are also likely to influence the results of supervised machine learning algorithms. It may be possible to partly remove the influence of scanner field strength and the presence of Gadolinium based contrast in feature extraction for radiomics applications.

  8. High-resolution small field-of-view magnetic resonance image acquisition system using a small planar coil and a pneumatic manipulator in an open MRI scanner.

    PubMed

    Miki, Kohei; Masamune, Ken

    2015-10-01

    Low-field open magnetic resonance imaging (MRI) is frequently used for performing image-guided neurosurgical procedures. Intraoperative magnetic resonance (MR) images are useful for tracking brain shifts and verifying residual tumors. However, it is difficult to precisely determine the boundary of the brain tumors and normal brain tissues because the MR image resolution is low, especially when using a low-field open MRI scanner. To overcome this problem, a high-resolution MR image acquisition system was developed and tested. An MR-compatible manipulator with pneumatic actuators containing an MR signal receiver with a small radiofrequency (RF) coil was developed. The manipulator had five degrees of freedom for position and orientation control of the RF coil. An 8-mm planar RF coil with resistance and inductance of 2.04 [Formula: see text] and 1.00 [Formula: see text] was attached to the MR signal receiver at the distal end of the probe. MR images of phantom test devices were acquired using the MR signal receiver and normal head coil for signal-to-noise ratio (SNR) testing. The SNR of MR images acquired using the MR signal receiver was 8.0 times greater than that of MR images acquired using the normal head coil. The RF coil was moved by the manipulator, and local MR images of a phantom with a 2-mm grid were acquired using the MR signal receiver. A wide field-of-view MR image was generated from a montage of local MR images. A small field-of-view RF system with a pneumatic manipulator was integrated in a low-field MRI scanner to allow acquisition of both wide field-of-view and high-resolution MR images. This system is promising for image-guided neurosurgery as it may allow brain tumors to be observed more clearly and removed precisely.

  9. Preliminary evaluation of a monolithic detector module for integrated PET/MRI scanner with high spatial resolution

    NASA Astrophysics Data System (ADS)

    Pani, R.; Gonzalez, A. J.; Bettiol, M.; Fabbri, A.; Cinti, M. N.; Preziosi, E.; Borrazzo, C.; Conde, P.; Pellegrini, R.; Di Castro, E.; Majewski, S.

    2015-06-01

    The proposal of Mindview European Project concerns with the development of a very high resolution and high efficiency brain dedicated PET scanner simultaneously working with a Magnetic Resonance scanner, that expects to visualize neurotransmitter pathways and their disruptions in the quest to better diagnose schizophrenia. On behalf of this project, we propose a low cost PET module for the first prototype, based on monolithic crystals, suitable to be integrated with a head Radio Frequency (RF) coil. The aim of the suggested module is to achieve high performances in terms of efficiency, planar spatial resolution (expected about 1 mm) and discrimination of gamma Depth Of Interaction (DOI) in order to reduce the parallax error. Our preliminary results are very promising: a DOI resolution of about 3 mm, a spatial resolution ranging from about 1 to 1.5 mm and a good position linearity.

  10. Graphical programming interface: A development environment for MRI methods.

    PubMed

    Zwart, Nicholas R; Pipe, James G

    2015-11-01

    To introduce a multiplatform, Python language-based, development environment called graphical programming interface for prototyping MRI techniques. The interface allows developers to interact with their scientific algorithm prototypes visually in an event-driven environment making tasks such as parameterization, algorithm testing, data manipulation, and visualization an integrated part of the work-flow. Algorithm developers extend the built-in functionality through simple code interfaces designed to facilitate rapid implementation. This article shows several examples of algorithms developed in graphical programming interface including the non-Cartesian MR reconstruction algorithms for PROPELLER and spiral as well as spin simulation and trajectory visualization of a FLORET example. The graphical programming interface framework is shown to be a versatile prototyping environment for developing numeric algorithms used in the latest MR techniques. © 2014 Wiley Periodicals, Inc.

  11. An approach for preoperative planning and performance of MR-guided interventions demonstrated with a manual manipulator in a 1.5T MRI scanner.

    PubMed

    Seimenis, Ioannis; Tsekos, Nikolaos V; Keroglou, Christoforos; Eracleous, Eleni; Pitris, Constantinos; Christoforou, Eftychios G

    2012-04-01

    The aim of this work was to develop and test a general methodology for the planning and performance of robot-assisted, MR-guided interventions. This methodology also includes the employment of software tools with appropriately tailored routines to effectively exploit the capabilities of MRI and address the relevant spatial limitations. The described methodology consists of: (1) patient-customized feasibility study that focuses on the geometric limitations imposed by the gantry, the robotic hardware, and interventional tools, as well as the patient; (2) stereotactic preoperative planning for initial positioning of the manipulator and alignment of its end-effector with a selected target; and (3) real-time, intraoperative tool tracking and monitoring of the actual intervention execution. Testing was performed inside a standard 1.5T MRI scanner in which the MR-compatible manipulator is deployed to provide the required access. A volunteer imaging study demonstrates the application of the feasibility stage. A phantom study on needle targeting is also presented, demonstrating the applicability and effectiveness of the proposed preoperative and intraoperative stages of the methodology. For this purpose, a manually actuated, MR-compatible robotic manipulation system was used to accurately acquire a prescribed target through alternative approaching paths. The methodology presented and experimentally examined allows the effective performance of MR-guided interventions. It is suitable for, but not restricted to, needle-targeting applications assisted by a robotic manipulation system, which can be deployed inside a cylindrical scanner to provide the required access to the patient facilitating real-time guidance and monitoring.

  12. Patient-induced susceptibility effect on geometric distortion of clinical brain MRI for radiation treatment planning on a 3T scanner

    NASA Astrophysics Data System (ADS)

    Wang, H.; Balter, J.; Cao, Y.

    2013-02-01

    Concerns about the geometric accuracy of MRI in radiation therapy (RT) have been present since its invention. Although modern scanners typically have system levels of geometric accuracy that meet requirements of RT, subject-specific distortion is variable, and methods to in vivo assess and control patient-induced geometric distortion are not yet resolved. This study investigated the nature and magnitude of the subject-induced susceptibility effect on geometric distortions in clinical brain MRI, and tested the feasibility of in vivo quality control using field inhomogeneity mapping. For 19 consecutive patients scanned on a dedicated 3T MR scanner, B0 field inhomogeneity maps were acquired and analyzed to determine subject-induced distortions. For 3D T1 weighted images frequency-encoded with a bandwidth of 180 Hz/pixel, 86.9% of the estimated displacements were <0.5 mm, 97.4% <1 mm, and only 0.1% of displacements > 2 mm. The maximum displacement was <4 mm. The greatest distortions were observed at the interfaces with air at the sinuses. Displacements decayed to less than 1 mm over a distance of 8 mm. Metal surgical wires generated smaller distortions, with an averaged maximum displacement of 0.76 mm. Repeat acquisition of the field maps in 17 patients revealed a within-subject standard deviation of 0.25 ppm, equivalent to 0.22 mm displacement in the frequency-encoding direction in the 3D T1 weighted images. Susceptibility-induced voxel displacements in the brain are generally small, but should be monitored for precision RT. These effects are manageable at 3T and lower fields, and the methods applied can be used to monitor for potential local errors in individual patients, as well as to correct for local distortions as needed.

  13. An Approach for Preoperative Planning and Performance of MR-guided Interventions Demonstrated With a Manual Manipulator in a 1.5T MRI Scanner

    SciTech Connect

    Seimenis, Ioannis; Tsekos, Nikolaos V.; Keroglou, Christoforos; Eracleous, Eleni; Pitris, Constantinos; Christoforou, Eftychios G.

    2012-04-15

    Purpose: The aim of this work was to develop and test a general methodology for the planning and performance of robot-assisted, MR-guided interventions. This methodology also includes the employment of software tools with appropriately tailored routines to effectively exploit the capabilities of MRI and address the relevant spatial limitations. Methods: The described methodology consists of: (1) patient-customized feasibility study that focuses on the geometric limitations imposed by the gantry, the robotic hardware, and interventional tools, as well as the patient; (2) stereotactic preoperative planning for initial positioning of the manipulator and alignment of its end-effector with a selected target; and (3) real-time, intraoperative tool tracking and monitoring of the actual intervention execution. Testing was performed inside a standard 1.5T MRI scanner in which the MR-compatible manipulator is deployed to provide the required access. Results: A volunteer imaging study demonstrates the application of the feasibility stage. A phantom study on needle targeting is also presented, demonstrating the applicability and effectiveness of the proposed preoperative and intraoperative stages of the methodology. For this purpose, a manually actuated, MR-compatible robotic manipulation system was used to accurately acquire a prescribed target through alternative approaching paths. Conclusions: The methodology presented and experimentally examined allows the effective performance of MR-guided interventions. It is suitable for, but not restricted to, needle-targeting applications assisted by a robotic manipulation system, which can be deployed inside a cylindrical scanner to provide the required access to the patient facilitating real-time guidance and monitoring.

  14. Cerebral correlates of heart rate variations during a spontaneous panic attack in the fMRI scanner.

    PubMed

    Spiegelhalder, Kai; Hornyak, Magdolna; Kyle, Simon David; Paul, Dominik; Blechert, Jens; Seifritz, Erich; Hennig, Jürgen; Tebartz van Elst, Ludger; Riemann, Dieter; Feige, Bernd

    2009-12-01

    We report the first published case study of a suddenly occurring panic attack in a patient with no prior history of panic disorder during combined functional magnetic resonance imaging (fMRI, 1.5 Tesla) and electrocardiogram (ECG) recording. The single case was a 46-year-old woman who developed a panic attack near the planned end of the fMRI acquisition session, which therefore had to be aborted. Correlational analysis of heart rate fluctuations and fMRI data revealed a significant negative association in the left middle temporal gyrus. Additionally, regions-of-interest (ROI) analyses indicated significant positive associations in the left amygdala, and trends towards significance in the right amygdala and left insula.

  15. Attenuation correction methods suitable for brain imaging with a PET/MRI scanner: a comparison of tissue atlas and template attenuation map approaches.

    PubMed

    Malone, Ian B; Ansorge, Richard E; Williams, Guy B; Nestor, Peter J; Carpenter, T Adrian; Fryer, Tim D

    2011-07-01

    Modeled attenuation correction (AC) will be necessary for combined PET/MRI scanners not equipped with transmission scanning hardware. We compared 2 modeled AC approaches that use nonrigid registration with rotating (68)Ge rod-based measured AC for 10 subjects scanned with (18)F-FDG. Two MRI and attenuation map pairs were evaluated: tissue atlas-based and measured templates. The tissue atlas approach used a composite of the BrainWeb and Zubal digital phantoms, whereas the measured templates were produced by averaging spatially normalized measured MR image and coregistered attenuation maps. The composite digital phantom was manually edited to include 2 additional tissue classes (paranasal sinuses, and ethmoidal air cells or nasal cavity). In addition, 3 attenuation values for bone were compared. The MRI and attenuation map pairs were used to generate subject-specific attenuation maps via nonrigid registration of the MRI to the MR image of the subject. SPM2 and a B-spline free-form deformation algorithm were used for the nonrigid registration. To determine the accuracy of the modeled AC approaches, radioactivity concentration was assessed on a voxelwise and regional basis. The template approach produced better spatial consistency than the phantom-based atlas, with an average percentage error in radioactivity concentration across the regions, compared with measured AC, of -1.2% ± 1.2% and -1.5% ± 1.9% for B-spline and SPM2 registration, respectively. In comparison, the tissue atlas method with B-spline registration produced average percentage errors of 0.0% ± 3.0%, 0.9% ± 2.9%, and 2.9% ± 2.8% for bone attenuation values of 0.143 cm(-1), 0.152 cm(-1), and 0.172 cm(-1), respectively. The largest errors for the template AC method were found in parts of the frontal cortex (-3%) and the cerebellar vermis (-5%). Intersubject variability was higher with SPM2 than with B-spline. Compared with measured AC, template AC with B-spline and SPM2 achieved a correlation

  16. The impact of simulated MRI scanner background noise on visual attention processes as measured by the EEG

    PubMed Central

    Kobald, S. Oliver; Getzmann, Stephan; Beste, Christian; Wascher, Edmund

    2016-01-01

    Environmental noise is known to affect personal well-being as well as cognitive processes. Besides daily life, environmental noise can also occur in experimental research settings, e.g. when being in a magnetic resonance scanner. Scanner background noise (SBN) might pose serious confounds for experimental findings, even when non-auditory settings are examined. In the current experiment we tested if SBN alters bottom-up and top-down related processes of selective visual attention mechanisms. Participants completed two blocks of a visual change detection task, one block in silence and one block under SBN exposure. SBN was found to decrease accuracy in measures of visual attention. This effect was modulated by the temporal occurrence of SBN. When SBN was encountered in the first block, it prevented a significant improvement of accuracy in the second block. When SBN appeared in the second block, it significantly decreased accuracy. Neurophysiological findings showed a strong frontal positivity shift only when SBN was present in the first block, suggesting an inhibitory process to counteract the interfering SBN. Common correlates of both top-down and bottom-up processes of selective visual attention were not specifically affected by SBN exposure. Further research appears necessary to entirely rule out confounds of SBN in assessing visual attention. PMID:27324456

  17. The impact of simulated MRI scanner background noise on visual attention processes as measured by the EEG.

    PubMed

    Kobald, S Oliver; Getzmann, Stephan; Beste, Christian; Wascher, Edmund

    2016-06-21

    Environmental noise is known to affect personal well-being as well as cognitive processes. Besides daily life, environmental noise can also occur in experimental research settings, e.g. when being in a magnetic resonance scanner. Scanner background noise (SBN) might pose serious confounds for experimental findings, even when non-auditory settings are examined. In the current experiment we tested if SBN alters bottom-up and top-down related processes of selective visual attention mechanisms. Participants completed two blocks of a visual change detection task, one block in silence and one block under SBN exposure. SBN was found to decrease accuracy in measures of visual attention. This effect was modulated by the temporal occurrence of SBN. When SBN was encountered in the first block, it prevented a significant improvement of accuracy in the second block. When SBN appeared in the second block, it significantly decreased accuracy. Neurophysiological findings showed a strong frontal positivity shift only when SBN was present in the first block, suggesting an inhibitory process to counteract the interfering SBN. Common correlates of both top-down and bottom-up processes of selective visual attention were not specifically affected by SBN exposure. Further research appears necessary to entirely rule out confounds of SBN in assessing visual attention.

  18. Three-dimensional ultrashort echo time imaging of solid polymers on a 3-Tesla whole-body MRI scanner.

    PubMed

    Springer, Fabian; Martirosian, Petros; Schwenzer, Nina F; Szimtenings, Michael; Kreisler, Peter; Claussen, Claus D; Schick, Fritz

    2008-11-01

    With the introduction of ultrashort echo time (UTE) sequences solid polymeric materials might become visible on clinical whole-body magnetic resonance (MR) scanners. The aim of this study was to characterize solid polymeric materials typically used for instruments in magnetic resonance guided interventions and implants. Relaxation behavior and signal yield were evaluated on a 3-Tesla whole-body MR unit. Nine different commonly used solid polymeric materials were investigated by means of a 3-dimensional (3D) UTE sequence with radial k-space sampling. The investigated polymeric samples with cylindrical shape (length, 150 mm; diameter, 30 mm) were placed in a commercial 8-channel knee coil. For assessment of transverse signal decay (T2*) images with variable echo times (TE) ranging from 0.07 milliseconds to 4.87 milliseconds were recorded. Spin-lattice relaxation time (T1) was calculated for all MR visible polymers with transverse relaxation times higher than T2* = 300 mus using an adapted method applying variable flip angles. Signal-to-noise ratio (SNR) was calculated at the shortest achievable echo time (TE = 0.07 milliseconds) for standardized sequence parameters. All relaxation times and SNR data are given as arithmetic mean values with standard deviations derived from 5 axially oriented slices placed around the isocenter of the coil and magnet. Six of the 9 investigated solid polymers were visible at TE = 0.07 milliseconds. Visible solid polymers showed markedly different SNR values, ie, polyethylene SNR = 1146 +/- 41, polypropylene SNR = 60 +/- 6. Nearly mono-exponential echo time dependent signal decay was observed: Transverse relaxation times differed from T2*=36 +/- 5 mus for polycarbonate to T2*=792 +/- 7 mus for polyvinylchloride (PVC). Two of the investigated solid polymers were applicable to T1 relaxation time calculation. Polyurethane had a spin-lattice relaxation time of T1 = 172 +/- 1 milliseconds, whereas PVC had T1 = 262 +/- 7 milliseconds

  19. Probabilistic atlas-based segmentation of combined T1-weighted and DUTE MRI for calculation of head attenuation maps in integrated PET/MRI scanners

    PubMed Central

    Poynton, Clare B; Chen, Kevin T; Chonde, Daniel B; Izquierdo-Garcia, David; Gollub, Randy L; Gerstner, Elizabeth R; Batchelor, Tracy T; Catana, Ciprian

    2014-01-01

    We present a new MRI-based attenuation correction (AC) approach for integrated PET/MRI systems that combines both segmentation- and atlas-based methods by incorporating dual-echo ultra-short echo-time (DUTE) and T1-weighted (T1w) MRI data and a probabilistic atlas. Segmented atlases were constructed from CT training data using a leave-one-out framework and combined with T1w, DUTE, and CT data to train a classifier that computes the probability of air/soft tissue/bone at each voxel. This classifier was applied to segment the MRI of the subject of interest and attenuation maps (μ-maps) were generated by assigning specific linear attenuation coefficients (LACs) to each tissue class. The μ-maps generated with this “Atlas-T1w-DUTE” approach were compared to those obtained from DUTE data using a previously proposed method. For validation of the segmentation results, segmented CT μ-maps were considered to the “silver standard”; the segmentation accuracy was assessed qualitatively and quantitatively through calculation of the Dice similarity coefficient (DSC). Relative change (RC) maps between the CT and MRI-based attenuation corrected PET volumes were also calculated for a global voxel-wise assessment of the reconstruction results. The μ-maps obtained using the Atlas-T1w-DUTE classifier agreed well with those derived from CT; the mean DSCs for the Atlas-T1w-DUTE-based μ-maps across all subjects were higher than those for DUTE-based μ-maps; the atlas-based μ-maps also showed a lower percentage of misclassified voxels across all subjects. RC maps from the atlas-based technique also demonstrated improvement in the PET data compared to the DUTE method, both globally as well as regionally. PMID:24753982

  20. Probabilistic atlas-based segmentation of combined T1-weighted and DUTE MRI for calculation of head attenuation maps in integrated PET/MRI scanners.

    PubMed

    Poynton, Clare B; Chen, Kevin T; Chonde, Daniel B; Izquierdo-Garcia, David; Gollub, Randy L; Gerstner, Elizabeth R; Batchelor, Tracy T; Catana, Ciprian

    2014-01-01

    We present a new MRI-based attenuation correction (AC) approach for integrated PET/MRI systems that combines both segmentation- and atlas-based methods by incorporating dual-echo ultra-short echo-time (DUTE) and T1-weighted (T1w) MRI data and a probabilistic atlas. Segmented atlases were constructed from CT training data using a leave-one-out framework and combined with T1w, DUTE, and CT data to train a classifier that computes the probability of air/soft tissue/bone at each voxel. This classifier was applied to segment the MRI of the subject of interest and attenuation maps (μ-maps) were generated by assigning specific linear attenuation coefficients (LACs) to each tissue class. The μ-maps generated with this "Atlas-T1w-DUTE" approach were compared to those obtained from DUTE data using a previously proposed method. For validation of the segmentation results, segmented CT μ-maps were considered to the "silver standard"; the segmentation accuracy was assessed qualitatively and quantitatively through calculation of the Dice similarity coefficient (DSC). Relative change (RC) maps between the CT and MRI-based attenuation corrected PET volumes were also calculated for a global voxel-wise assessment of the reconstruction results. The μ-maps obtained using the Atlas-T1w-DUTE classifier agreed well with those derived from CT; the mean DSCs for the Atlas-T1w-DUTE-based μ-maps across all subjects were higher than those for DUTE-based μ-maps; the atlas-based μ-maps also showed a lower percentage of misclassified voxels across all subjects. RC maps from the atlas-based technique also demonstrated improvement in the PET data compared to the DUTE method, both globally as well as regionally.

  1. A low-cost and versatile system for projecting wide-field visual stimuli within fMRI scanners

    PubMed Central

    Greco, V.; Frijia, F.; Mikellidou, K.; Montanaro, D.; Farini, A.; D’Uva, M.; Poggi, P.; Pucci, M.; Sordini, A.; Morrone, M. C.; Burr, D. C.

    2016-01-01

    We have constructed and tested a custom-made magnetic-imaging-compatible visual projection system designed to project on a very wide visual field (~80°). A standard projector was modified with a coupling lens, projecting images into the termination of an image fiber. The other termination of the fiber was placed in the 3-T scanner room with a projection lens, which projected the images relayed by the fiber onto a screen over the head coil, viewed by a participant wearing magnifying goggles. To validate the system, wide-field stimuli were presented in order to identify retinotopic visual areas. The results showed that this low-cost and versatile optical system may be a valuable tool to map visual areas in the brain that process peripheral receptive fields. PMID:26092392

  2. A low-cost and versatile system for projecting wide-field visual stimuli within fMRI scanners.

    PubMed

    Greco, V; Frijia, F; Mikellidou, K; Montanaro, D; Farini, A; D'Uva, M; Poggi, P; Pucci, M; Sordini, A; Morrone, M C; Burr, D C

    2016-06-01

    We have constructed and tested a custom-made magnetic-imaging-compatible visual projection system designed to project on a very wide visual field (~80°). A standard projector was modified with a coupling lens, projecting images into the termination of an image fiber. The other termination of the fiber was placed in the 3-T scanner room with a projection lens, which projected the images relayed by the fiber onto a screen over the head coil, viewed by a participant wearing magnifying goggles. To validate the system, wide-field stimuli were presented in order to identify retinotopic visual areas. The results showed that this low-cost and versatile optical system may be a valuable tool to map visual areas in the brain that process peripheral receptive fields.

  3. Integrating a MRI scanner with a 6 MV radiotherapy accelerator: dose deposition in a transverse magnetic field.

    PubMed

    Raaymakers, B W; Raaijmakers, A J E; Kotte, A N T J; Jette, D; Lagendijk, J J W

    2004-09-07

    Integrating magnetic resonance imaging (MRI) functionality with a radiotherapy accelerator can facilitate on-line, soft-tissue based, position verification. A technical feasibility study, in collaboration with Elekta Oncology Systems and Philips Medical Systems, led to the preliminary design specifications of a MRI accelerator. Basically the design is a 6 MV accelerator rotating around a 1.5 T MRI system. Several technical issues and the clinical rational are currently under investigation. The aim of this paper is to determine the impact of the transverse 1.5 T magnetic field on the dose deposition. Monte Carlo simulations were used to calculate the dose deposition kernel in the presence of 1.5 T. This kernel in turn was used to determine the dose deposition for larger fields. Also simulations and measurements were done in the presence of 1.1 T. The pencil beam dose deposition is asymmetric. For larger fields the asymmetry persists but decreases. For the latter the distance to dose maximum is reduced by approximately 5 mm, the penumbra is increased by approximately 1 mm, and the 50% isodose line is shifted approximately 1 mm. The dose deposition in the presence of 1.5 T is affected, but the effect can be taken into account in a conventional treatment planning procedure. The impact of the altered dose deposition for clinical IMRT treatments is the topic of further research.

  4. Aerial vehicle navigation over unknown terrain environments using inertial measurements and dual airborne laser scanners or flash ladar

    NASA Astrophysics Data System (ADS)

    Vadlamani, Ananth K.; Uijt de Haag, Maarten

    2007-04-01

    A precise navigation system for uninhabited or inhabited aerial vehicles is discussed in this paper. The navigational capability of an aerial vehicle must be robust and not easily influenced by external factors. Nowadays, many navigation systems rely somehow on the Global Positioning System (GPS), wherein the GPS signals may be rendered unusable due to unintentional interference caused by atmospheric effects, interference from communication equipment, as well as intentional jamming. The navigation method discussed in this paper integrates measurements from an Inertial Measurement Unit (IMU) with measurements from either two airborne laser scanners (ALS) or an airborne Flash LADAR (AFL) to provide autonomous navigational capability and a reliable alternative to GPS. The proposed system has applications in unknown or partially known terrain environments or it may also be used for autonomous landing systems in Lunar or Martian environments. Two approaches are described in this paper, one approach uses Dual Airborne Laser Scanners (DALS) (one pointing forward, the other pointing aft) and the other approach uses an AFL. Advantages and disadvantages of both approaches are discussed. The proposed navigation system uses strapdown IMU measurements to estimate the aerial vehicle position and attitude and to geo-reference the laser sensor data. It then uses the maps created from both the fore and aftpointing scanning LADARS or the consecutive Flash LADAR range-images to estimate systematic IMU errors such as position and velocity drifts. The proposed navigation algorithm is evaluated using flight test data from Ohio University's DC3 aircraft and synthesized ALS and AFL measurements. Initial results are observed to achieve meter level accuracies in the system's position drift performance.

  5. Evaluation of two-dimensional L-COSY and JPRESS using a 3 T MRI scanner: from phantoms to human brain in vivo.

    PubMed

    Thomas, M Albert; Hattori, Noriaki; Umeda, Masahiro; Sawada, Tohru; Naruse, Shoji

    2003-08-01

    Localized versions of two-dimensional (2D) magnetic resonance spectroscopic (MRS) sequences, namely JPRESS and L-COSY, have been implemented on a whole-body 3T MRI/MRS scanner. Volume selection was achieved using three slice-selective radio-frequency (RF) pulses: 90 degrees-180 degrees-180 degrees in JPRESS and 90 degrees-180 degrees-90 degrees in L-COSY with a CHESS sequence prior to voxel localization for global water suppression. The last 180 degrees RF pulse was used for resolving the J-coupled cross peaks in JPRESS, whereas the last 90 degrees RF pulse was used for coherence transfer between J-coupled metabolites in L-COSY. A head MRI coil for 'transmission' and a 4 inch receive surface coil for 'reception' or a head coil transmit/receive were used. A total of 16 healthy volunteers were investigated using these 2D MRS sequences. Voxel sizes of 18 and 27 ml were localized in the occipito-parietal gray and white matter regions and the total duration for each 2D signal acquisition was typically 35 min. Compared with 2D L-COSY, reduced spectral width along the second spectral dimension and shorter 2D spectral acquisition were the major advantages of 2D JPRESS. In contrast, increased spectral width along the new spectral dimension in L-COSY resulted in an improved spectral dispersion enabling the detection of several brain metabolites at low concentrations that have not been resolved using the conventional one-dimensional (1D) MRS techniques. Due to increased sampling rate, severe loss of metabolite signals due to T2 during t1 was a major drawback of 2D JPRESS in vivo. Copyright 2003 John Wiley & Sons, Ltd.

  6. MR Spectroscopic Imaging of Peripheral Zone in Prostate Cancer Using a 3T MRI Scanner: Endorectal versus External Phased Array Coils.

    PubMed

    Nagarajan, Rajakumar; Margolis, Daniel Ja; Raman, Steven S; Ouellette, David; Sarma, Manoj K; Reiter, Robert E; Thomas, M Albert

    2013-01-01

    Magnetic resonance spectroscopic imaging (MRSI) detects alterations in major prostate metabolites, such as citrate (Cit), creatine (Cr), and choline (Ch). We evaluated the sensitivity and accuracy of three-dimensional MRSI of prostate using an endorectal compared to an external phased array "receive" coil on a 3T MRI scanner. Eighteen patients with prostate cancer (PCa) who underwent endorectal MR imaging and proton (1H) MRSI were included in this study. Immediately after the endorectal MRSI scan, the PCa patients were scanned with the external phased array coil. The endorectal coil-detected metabolite ratio [(Ch+Cr)/Cit] was significantly higher in cancer locations (1.667 ± 0.663) compared to non-cancer locations (0.978 ± 0.420) (P < 0.001). Similarly, for the external phased array, the ratio was significantly higher in cancer locations (1.070 ± 0.525) compared to non-cancer locations (0.521 ± 0.310) (P < 0.001). The sensitivity and accuracy of cancer detection were 81% and 78% using the endorectal 'receive' coil, and 69% and 75%, respectively using the external phased array 'receive' coil.

  7. Integrating a MRI scanner with a 6 MV radiotherapy accelerator: dose increase at tissue-air interfaces in a lateral magnetic field due to returning electrons.

    PubMed

    Raaijmakers, A J E; Raaymakers, B W; Lagendijk, J J W

    2005-04-07

    In the framework of the development of the integration of a MRI-scanner with a linear accelerator, the influence of a lateral, magnetic field on the dose distribution has to be determined. Dose increase is expected at tissue-air boundaries, due to the electron return effect (ERE): electrons entering air will describe a circular path and return into the phantom causing extra dose deposition. Using IMRT with many beam directions, this exit dose will not constitute a problem. Dose levels behind air cavities will decrease because of the absence of electrons crossing the cavity. The ERE has been demonstrated both by simulation and experiment. Monte Carlo simulations are performed with GEANT4, irradiating a water-air-water phantom in a lateral magnetic field. Also an air tube in water has been simulated, resulting in slightly twisted regions of dose increase and decrease. Experimental demonstration is achieved by film measurement in a perspex-air-perspex phantom in an electromagnet. Although the ERE causes dose increase before air cavities, relatively flat dose profiles can be obtained for the investigated cases using opposite beam configurations. More research will be necessary whether this holds for more realistic geometries with the use of IMRT and whether the ERE can be turned to our advantage when treating small tumour sites at air cavities.

  8. Objective Bayesian fMRI analysis—a pilot study in different clinical environments

    PubMed Central

    Magerkurth, Joerg; Mancini, Laura; Penny, William; Flandin, Guillaume; Ashburner, John; Micallef, Caroline; De Vita, Enrico; Daga, Pankaj; White, Mark J.; Buckley, Craig; Yamamoto, Adam K.; Ourselin, Sebastien; Yousry, Tarek; Thornton, John S.; Weiskopf, Nikolaus

    2015-01-01

    Functional MRI (fMRI) used for neurosurgical planning delineates functionally eloquent brain areas by time-series analysis of task-induced BOLD signal changes. Commonly used frequentist statistics protect against false positive results based on a p-value threshold. In surgical planning, false negative results are equally if not more harmful, potentially masking true brain activity leading to erroneous resection of eloquent regions. Bayesian statistics provides an alternative framework, categorizing areas as activated, deactivated, non-activated or with low statistical confidence. This approach has not yet found wide clinical application partly due to the lack of a method to objectively define an effect size threshold. We implemented a Bayesian analysis framework for neurosurgical planning fMRI. It entails an automated effect-size threshold selection method for posterior probability maps accounting for inter-individual BOLD response differences, which was calibrated based on the frequentist results maps thresholded by two clinical experts. We compared Bayesian and frequentist analysis of passive-motor fMRI data from 10 healthy volunteers measured on a pre-operative 3T and an intra-operative 1.5T MRI scanner. As a clinical case study, we tested passive motor task activation in a brain tumor patient at 3T under clinical conditions. With our novel effect size threshold method, the Bayesian analysis revealed regions of all four categories in the 3T data. Activated region foci and extent were consistent with the frequentist analysis results. In the lower signal-to-noise ratio 1.5T intra-operative scanner data, Bayesian analysis provided improved brain-activation detection sensitivity compared with the frequentist analysis, albeit the spatial extents of the activations were smaller than at 3T. Bayesian analysis of fMRI data using operator-independent effect size threshold selection may improve the sensitivity and certainty of information available to guide neurosurgery

  9. Objective Bayesian fMRI analysis-a pilot study in different clinical environments.

    PubMed

    Magerkurth, Joerg; Mancini, Laura; Penny, William; Flandin, Guillaume; Ashburner, John; Micallef, Caroline; De Vita, Enrico; Daga, Pankaj; White, Mark J; Buckley, Craig; Yamamoto, Adam K; Ourselin, Sebastien; Yousry, Tarek; Thornton, John S; Weiskopf, Nikolaus

    2015-01-01

    Functional MRI (fMRI) used for neurosurgical planning delineates functionally eloquent brain areas by time-series analysis of task-induced BOLD signal changes. Commonly used frequentist statistics protect against false positive results based on a p-value threshold. In surgical planning, false negative results are equally if not more harmful, potentially masking true brain activity leading to erroneous resection of eloquent regions. Bayesian statistics provides an alternative framework, categorizing areas as activated, deactivated, non-activated or with low statistical confidence. This approach has not yet found wide clinical application partly due to the lack of a method to objectively define an effect size threshold. We implemented a Bayesian analysis framework for neurosurgical planning fMRI. It entails an automated effect-size threshold selection method for posterior probability maps accounting for inter-individual BOLD response differences, which was calibrated based on the frequentist results maps thresholded by two clinical experts. We compared Bayesian and frequentist analysis of passive-motor fMRI data from 10 healthy volunteers measured on a pre-operative 3T and an intra-operative 1.5T MRI scanner. As a clinical case study, we tested passive motor task activation in a brain tumor patient at 3T under clinical conditions. With our novel effect size threshold method, the Bayesian analysis revealed regions of all four categories in the 3T data. Activated region foci and extent were consistent with the frequentist analysis results. In the lower signal-to-noise ratio 1.5T intra-operative scanner data, Bayesian analysis provided improved brain-activation detection sensitivity compared with the frequentist analysis, albeit the spatial extents of the activations were smaller than at 3T. Bayesian analysis of fMRI data using operator-independent effect size threshold selection may improve the sensitivity and certainty of information available to guide neurosurgery.

  10. Response competition and response inhibition during different choice-discrimination tasks: evidence from ERP measured inside MRI scanner.

    PubMed

    Gonzalez-Rosa, Javier J; Inuggi, Alberto; Blasi, Valeria; Cursi, Marco; Annovazzi, Pietro; Comi, Giancarlo; Falini, Andrea; Leocani, Letizia

    2013-07-01

    We investigated the neural correlates underlying response inhibition and conflict detection processes using ERPs and source localization analyses simultaneously acquired during fMRI scanning. ERPs were elicited by a simple reaction time task (SRT), a Go/NoGo task, and a Stroop-like task (CST). The cognitive conflict was thus manipulated in order to probe the degree to which information processing is shared across cognitive systems. We proposed to dissociate inhibition and interference conflict effects on brain activity by using identical Stroop-like congruent/incongruent stimuli in all three task contexts and while varying the response required. NoGo-incongruent trials showed a larger N2 and enhanced activations of rostral anterior cingulate cortex (ACC) and pre-supplementary motor area, whereas Go-congruent trials showed a larger P3 and increased parietal activations. Congruent and incongruent conditions of the CST task also elicited similar N2, P3 and late negativity (LN) ERPs, though CST-incongruent trials revealed a larger LN and enhanced prefrontal and ACC activations. Considering the stimulus probability and experimental manipulation of our study, current findings suggest that NoGo N2 and frontal NoGo P3 appear to be more associated to response inhibition rather than a specific conflict monitoring, whereas occipito-parietal P3 of Go and CST conditions may be more linked to a planned response competition between the prepared and required response. LN, however, appears to be related to higher level conflict monitoring associated with response choice-discrimination but not when the presence of cognitive conflict is associated with response inhibition. Copyright © 2013. Published by Elsevier B.V.

  11. Can the Neural Basis of Repression Be Studied in the MRI Scanner? New Insights from Two Free Association Paradigms

    PubMed Central

    Kessler, Henrik; Do Lam, Anne T. A.; Fell, Juergen; Schmidt, Anna-Christine; Axmacher, Nikolai

    2013-01-01

    Background The psychodynamic theory of repression suggests that experiences which are related to internal conflicts become unconscious. Previous attempts to investigate repression experimentally were based on voluntary, intentional suppression of stimulus material. Unconscious repression of conflict-related material is arguably due to different processes, but has never been studied with neuroimaging methods. Methods We used functional magnetic resonance imaging (fMRI) in addition with skin conductance recordings during two free association paradigms to identify the neural mechanisms underlying forgetting of freely associated words according to repression theory. Results In the first experiment, free association to subsequently forgotten words was accompanied by increases in skin conductance responses (SCRs) and reaction times (RTs), indicating autonomic arousal, and by activation of the anterior cingulate cortex. These findings are consistent with the hypothesis that these associations were repressed because they elicited internal conflicts. To test this idea more directly, we conducted a second experiment in which participants freely associated to conflict-related sentences. Indeed, these associations were more likely to be forgotten than associations to not conflict-related sentences and were accompanied by increases in SCRs and RTs. Furthermore, we observed enhanced activation of the anterior cingulate cortex and deactivation of hippocampus and parahippocampal cortex during association to conflict-related sentences. Conclusions These two experiments demonstrate that high autonomic arousal during free association predicts subsequent memory failure, accompanied by increased activation of conflict-related and deactivation of memory-related brain regions. These results are consistent with the hypothesis that during repression, explicit memory systems are down-regulated by the anterior cingulate cortex. PMID:23638050

  12. Can the neural basis of repression be studied in the MRI scanner? New insights from two free association paradigms.

    PubMed

    Schmeing, Jo-Birger; Kehyayan, Aram; Kessler, Henrik; Do Lam, Anne T A; Fell, Juergen; Schmidt, Anna-Christine; Axmacher, Nikolai

    2013-01-01

    The psychodynamic theory of repression suggests that experiences which are related to internal conflicts become unconscious. Previous attempts to investigate repression experimentally were based on voluntary, intentional suppression of stimulus material. Unconscious repression of conflict-related material is arguably due to different processes, but has never been studied with neuroimaging methods. We used functional magnetic resonance imaging (fMRI) in addition with skin conductance recordings during two free association paradigms to identify the neural mechanisms underlying forgetting of freely associated words according to repression theory. In the first experiment, free association to subsequently forgotten words was accompanied by increases in skin conductance responses (SCRs) and reaction times (RTs), indicating autonomic arousal, and by activation of the anterior cingulate cortex. These findings are consistent with the hypothesis that these associations were repressed because they elicited internal conflicts. To test this idea more directly, we conducted a second experiment in which participants freely associated to conflict-related sentences. Indeed, these associations were more likely to be forgotten than associations to not conflict-related sentences and were accompanied by increases in SCRs and RTs. Furthermore, we observed enhanced activation of the anterior cingulate cortex and deactivation of hippocampus and parahippocampal cortex during association to conflict-related sentences. These two experiments demonstrate that high autonomic arousal during free association predicts subsequent memory failure, accompanied by increased activation of conflict-related and deactivation of memory-related brain regions. These results are consistent with the hypothesis that during repression, explicit memory systems are down-regulated by the anterior cingulate cortex.

  13. Induced magnetic moment in stainless steel components of orthodontic appliances in 1.5 T MRI scanners

    PubMed Central

    Rollins, Nancy K.; Liang, Hui; Park, Yong Jong

    2015-01-01

    Purpose: Most orthodontic appliances are made of stainless steel materials and induce severe magnetic susceptibility artifacts in brain MRI. In an effort for correcting these artifacts, it is important to know the value of induced magnetic moments in all parts of orthodontic appliances. In this study, the induced magnetic moment of stainless steel orthodontic brackets, molar bands, and arch-wires from several vendors is measured. Methods: Individual stainless steel brackets, molar bands, and short segments of arch-wire were positioned in the center of spherical flask filled with water through a thin plastic rod. The induced magnetic moment at 1.5 T was determined by fitting the B0 map to the z-component of the magnetic dipole field using a computer routine. Results: The induced magnetic moment at 1.5 T was dominated by the longitudinal component mz, with a small contribution from the transverse components. The mz was insensitive to the orientation of the metal parts. The orthodontic brackets collectively dominated the magnetic dipole moment in orthodontic appliances. In brackets from six vendors, the total induced mz from 20 brackets for nonmolar teeth ranged from 0.108 to 0.158 (median 0.122) A ⋅ m2. The mz in eight molar bands with bracket attachment from two vendors ranged from 0.0004 to 0.0166 (median 0.0035) A ⋅ m2. Several full length arch wires had induced magnetic moment in the range of 0.006–0.025 (median 0.015) A ⋅ m2. Conclusions: Orthodontic brackets collectively contributed most to the total magnetic moment. Different types of brackets, molar bands, and arch wires all exhibit substantial variability in the induced magnetic moment. PMID:26429261

  14. Scanner Art

    ERIC Educational Resources Information Center

    Jaworski, Joy; Murphy, Kris

    2009-01-01

    In this article, the authors describe how they incorporated environmental awareness into their art curriculum. Here, they describe a digital photography project in which their students used flatbed scanners as cameras. Their students composed their objects directly on the scanner. The lesson enabled students to realize that artists have voices…

  15. Scanner Art

    ERIC Educational Resources Information Center

    Jaworski, Joy; Murphy, Kris

    2009-01-01

    In this article, the authors describe how they incorporated environmental awareness into their art curriculum. Here, they describe a digital photography project in which their students used flatbed scanners as cameras. Their students composed their objects directly on the scanner. The lesson enabled students to realize that artists have voices…

  16. Skin and proximity effects in the conductors of split gradient coils for a hybrid Linac-MRI scanner

    NASA Astrophysics Data System (ADS)

    Tang, Fangfang; Lopez, Hector Sanchez; Freschi, Fabio; Smith, Elliot; Li, Yu; Fuentes, Miguel; Liu, Feng; Repetto, Maurizio; Crozier, Stuart

    2014-05-01

    In magnetic resonance imaging (MRI), rapidly changing gradient fields are applied to encode the magnetic resonance signal with spatial position; however eddy currents are induced in the surrounding conducting structures depending on the geometry of the conductor and the excitation waveform. These alternating fields change the spatial profile of the current density within the coil track with the applied frequencies of the input waveform and by their proximity to other conductors. In this paper, the impact of the conductor width and the excited frequency over the parameters that characterise the performance of split transverse and longitudinal gradient coils are studied. Thirty x-gradient coils were designed using a “free-surface” coil design method and the track width was varied from 1 mm to 30 mm with an increment value of 1 mm; a frequency sweep analysis in the range of 100 Hz to 10 kHz was performed using the multi-layer integral method (MIM) and parameters such as power loss produced by the coil and generated in the cryostat, inductance, coil efficiency (field strength/operating current), magnetic field profile produced by the coil and the eddy currents were studied. An experimental validation of the theoretical model was performed on an example coil. Coils with filamentary conductor segments were also studied to compare the simulated parameters with those produced by coils with a finite track. There was found to be a significant difference between the parameters calculated using filamentary coils and those obtained when the coil is simulated using finite size tracks. A wider track width produces coil with superior efficiency and low resistance; however, due to the skin effect, the power loss increases faster in wider tracks than in those generated in coils with narrow tracks. It was demonstrated that rapidly changing current paths must be avoided in order to mitigate the power loss and the spatial asymmetry in the current density profile. The decision of

  17. A cost-effective handheld breast scanner for use in low-resource environments: a validation study.

    PubMed

    Broach, Robyn B; Geha, Rula; Englander, Brian S; DeLaCruz, Lucy; Thrash, Holly; Brooks, Ari D

    2016-10-28

    With the incidence of breast cancer rising worldwide, we are evaluating the iBreastExam (iBE) (UE LifeSciences Inc.), a handheld breast scanning device that can be utilized by community health workers to screen for breast abnormalities. The purpose of this study is to determine the sensitivity of the iBE in a population undergoing diagnostic breast imaging. Adult patients presenting to a breast imaging center for a diagnostic workup were eligible. Patients underwent an iBE exam performed by a trained ultrasound technician followed by their indicated imaging. Demographic, imaging, and biopsy data were recorded. Seventy-eight iBE exams were completed, 77 females and one male with a mean age of 42 (21-79). All patients were evaluated by ultrasound, 52 had diagnostic mammography and 39 had biopsies. Imaging and/or biopsy confirmed a mass (fibroadenoma, cyst, papilloma, myofibroblastoma, fat necrosis, DCIS, or cancer) in 60 patients. Twelve patients had a cancer diagnosed. In total, 342 quadrants were scanned, 77 quadrants had lesions confirmed on imaging, and iBE correctly identified 66 lesions for a sensitivity of 86 % and specificity of 89 %. This validation study demonstrated excellent sensitivity of iBE for the identification of clinically significant lesions in patients presenting for diagnostic imaging. A Cost-Effective Handheld Breast Scanner for Use in Low Resource Environments: A Validation Study: NCT02814292 .

  18. Comparison of dynamic gadolinium-enhanced and ferumoxides-enhanced MRI of the liver on high- and low-field scanners.

    PubMed

    Limanond, Piyaporn; Raman, Steven S; Sayre, James; Lu, David S K

    2004-10-01

    To compare the performance of dynamic gadolinium-enhanced and ferumoxides-enhanced MRI in the detection and characterization of hepatic lesions, on 1.5-T and 0.2-T magnets In 41 patients (23 men, 18 women), 52 hepatic MR examinations were performed and retrospectively analyzed; 39 and 13 examinations were performed on 1.5-T and 0.2-T magnets, respectively. A total of 33 of 41 patients had known malignancies, and 31 of 33 patients had biopsy of at least one lesion. First, a combination of unenhanced T2-weighted sequences and gradient-echo T1-weighted sequences were performed. Then, dynamic gadolinium-enhanced (0.1 mmol/kg) T1 GRE sequences were obtained, followed by intravenous drip infusion of ferumoxides (10 micromol/kg). The T2-weighted sequences were then repeated. The unenhanced and gadolinium-enhanced images (the Gd set) were reviewed separately from the unenhanced and ferumoxides-enhanced images (the ferumoxides set) by two abdominal imagers. The reviewers were blinded to clinical history and reviewed the individual studies in each set randomly. Each detected lesion was scored on a five-point scale for characterization scores: nonsolid (1 or 2), indeterminate (3), or solid (4 or 5). A consensus review was then performed correlating all available pathology, imaging, clinical findings, and follow-up to act as a gold standard. Receiver-operating-characteristic (ROC) curves were generated and both area-under-the-curve (Az values) and sensitivity values were calculated. Significance of Az and sensitivity differences was assessed using standard Z-test and chi-square. Of 270 lesions detected by consensus, 211 were on 1.5-T and 59 were on 0.2-T scanners. The accuracy (Az values) of lesion detection overall, of both readers, was greater for the ferumoxides set than for the Gd set (reader 1: 0.95 vs. 0.89 (P < 0.05); reader 2: 0.91 vs. 0.78 (P < 0.05)). Az values for both readers were greater on the ferumoxides set for both the 1.5-T scans and the 0.2-T scans. Out of

  19. Within and between session changes in subjective and neuroendocrine stress parameters during magnetic resonance imaging: A controlled scanner training study.

    PubMed

    Lueken, Ulrike; Muehlhan, Markus; Evens, Ricarda; Wittchen, Hans-Ulrich; Kirschbaum, Clemens

    2012-08-01

    Accumulating evidence suggests that the magnetic resonance imaging (MRI) scanner can act as a stressor, eliciting subjective and neuroendocrine stress responses. Approaches to familiarize subjects with the scanner could help minimizing unintended effects on neural activation patterns of interest. Controlled studies on the effects of a scanner training are however missing. Using a comparative design, we analyzed within- and between session changes in subjective and neuroendocrine stress parameters in 63 healthy, scanner-naïve adults who participated in a two-day training protocol in an MRI, mock, or lab environment. A habituation task was used to assess within-session changes in subjective and neuroendocrine (cortisol) stress parameters; between-session changes were indicated by differences between days. MRI and mock, but not lab training were successful in reducing subjective distress towards the scanner. In contrast, cortisol reactivity towards the training environment generally increased during day 2, and the percentage of cortisol responders particularly rose in the mock and MRI groups. Within-session habituation of subjective arousal and anxiety was observed during both days and irrespective of training condition. Present findings demonstrate that training in a scanner environment successfully reduces subjective distress, but may also induce sensitization of endocrine stress levels during repeated scanning. Subjective distress can further be stabilized by acclimating subjects to the environment prior to the MRI assessment, including a short habituation phase into the assessment protocol. If replicated, present findings should be considered by researchers employing repeated measurement designs where subjects are exposed to a scanner more than once.

  20. Molecular imaging probes spy on the body's inner workings: miniaturized microscopes, microbubbles, 7- and 15-T scanners, diffusion-tensor MRI, and other molecular-imaging technologies are pushing molecular imaging into the future.

    PubMed

    Mertz, Leslie

    2013-01-01

    Molecular imaging is one of the hot-button areas within medical imaging. This technology employs imaging techniques in concert with molecular probes, or biomarkers, that together noninvasively spy on cellular function and molecular processes. In some cases, this technology may be able to detect the very earliest stages of diseases and eliminate them on the spot. This paper discusses how miniaturized microscopes, microbubbles, 7T and 15T scanners, diffusion-tensor MRI and other molecular imaging technologies are pushing molecular imaging into the future.

  1. The pattern of exposure to static magnetic field of nurses involved in activities related to contrast administration into patients diagnosed in 1.5 T MRI scanners.

    PubMed

    Karpowicz, Jolanta; Gryz, Krzysztof

    2013-06-01

    Static magnetic fields (SMFs) and time-varying electromagnetic fields exposure is necessary to obtain the diagnostic information regarding the structure of patient's tissues, by the use of magnetic resonance imaging (MRI) scanners. A diagnostic procedure may also include the administration of pharmaceuticals called contrast, which are to be applied to a patient during the examination. The nurses involved in administering contrast into a patient during the pause in examination are approaching permanently active magnets of MRI scanners and are exposed to SMF. There were performed measurements of spatial distribution of SMF in the vicinity of MRI magnets and parameters of personal exposure of nurses (i.e. individual exposimetric profiles of variability in time of SMF affecting the nurse who is performing tasks in the vicinity of magnet, characterized by statistical parameters of recorded magnetic flux density affecting the nurse). The SMF exposure in the vicinity of various MRI magnets depends on both magnetic flux density of the main field B 0 (applicable to a patient) and the construction of the scanner, but the most important factor determining the workers' exposure is the work practice. In the course of a patient's routine examination in scanners of B₀ = 1.5 T, the nurses are present over ∼0.4-2.9 min in SMF exceeding 0.03% of B₀ (i.e. 0.5 mT), but only sometimes they are present in SMF exceeding 5% of B 0 (i.e. 75 mT). When patients need more attention because of their health status/condition, the nurses' exposure may be significantly longer--it may even exceed 10 min and 30% of B 0 (i.e. 500 mT). We have found that the level of exposure of nurses to SMF may vary from < 5% of the main field (a median value: 0.5-1.5%; inter-quartile range: 0.04-8.8%; max value: 1.3-12% of B₀) when a patient is moved from the magnets bore before contrast administration, up to the main field level (B₀) when a patient stays in the magnets bore and nurse is crawling into the

  2. Simultaneous hyperpolarized 13C-pyruvate MRI and 18F-FDG-PET in cancer (hyperPET): feasibility of a new imaging concept using a clinical PET/MRI scanner

    PubMed Central

    Gutte, Henrik; Hansen, Adam E; Henriksen, Sarah T; Johannesen, Helle H; Ardenkjaer-Larsen, Jan; Vignaud, Alexandre; Hansen, Anders E; Børresen, Betina; Klausen, Thomas L; Wittekind, Anne-Mette N; Gillings, Nic; Kristensen, Annemarie T; Clemmensen, Andreas; Højgaard, Liselotte; Kjær, Andreas

    2015-01-01

    In this paper we demonstrate, for the first time, the feasibility of a new imaging concept - combined hyperpolarized 13C-pyruvate magnetic resonance spectroscopic imaging (MRSI) and 18F-FDG-PET imaging. This procedure was performed in a clinical PET/MRI scanner with a canine cancer patient. We have named this concept hyper PET. Intravenous injection of the hyperpolarized 13C-pyruvate results in an increase of 13C-lactate, 13C-alanine and 13C-CO2 (13C-HCO3) resonance peaks relative to the tissue, disease and the metabolic state probed. Accordingly, with dynamic nuclear polarization (DNP) and use of 13C-pyruvate it is now possible to directly study the Warburg Effect through the rate of conversion of 13C-pyruvate to 13C-lactate. In this study, we combined it with 18F-FDG-PET that studies uptake of glucose in the cells. A canine cancer patient with a histology verified local recurrence of a liposarcoma on the right forepaw was imaged using a combined PET/MR clinical scanner. PET was performed as a single-bed, 10 min acquisition, 107 min post injection of 310 MBq 18F-FDG. 13C-chemical shift imaging (CSI) was performed just after FDG-PET and 30 s post injection of 23 mL hyperpolarized 13C-pyruvate. Peak heights of 13C-pyruvate and 13C-lactate were quantified using a general linear model. Anatomic 1H-MRI included axial and coronal T1 vibe, coronal T2-tse and axial T1-tse with fat saturation following gadolinium injection. In the tumor we found clearly increased 13C-lactate production, which also corresponded to high 18F-FDG uptake on PET. This is in agreement with the fact that glycolysis and production of lactate are increased in tumor cells compared to normal cells. Yet, most interestingly, also in the muscle of the forepaw of the dog high 18F-FDG uptake was observed. This was due to activity in these muscles prior to anesthesia, which was not accompanied by a similarly high 13C-lactate production. Accordingly, this clearly demonstrates how the Warburg Effect directly

  3. Simultaneous hyperpolarized (13)C-pyruvate MRI and (18)F-FDG-PET in cancer (hyperPET): feasibility of a new imaging concept using a clinical PET/MRI scanner.

    PubMed

    Gutte, Henrik; Hansen, Adam E; Henriksen, Sarah T; Johannesen, Helle H; Ardenkjaer-Larsen, Jan; Vignaud, Alexandre; Hansen, Anders E; Børresen, Betina; Klausen, Thomas L; Wittekind, Anne-Mette N; Gillings, Nic; Kristensen, Annemarie T; Clemmensen, Andreas; Højgaard, Liselotte; Kjær, Andreas

    2015-01-01

    In this paper we demonstrate, for the first time, the feasibility of a new imaging concept - combined hyperpolarized (13)C-pyruvate magnetic resonance spectroscopic imaging (MRSI) and (18)F-FDG-PET imaging. This procedure was performed in a clinical PET/MRI scanner with a canine cancer patient. We have named this concept hyper PET. Intravenous injection of the hyperpolarized (13)C-pyruvate results in an increase of (13)C-lactate, (13)C-alanine and (13)C-CO2 ((13)C-HCO3) resonance peaks relative to the tissue, disease and the metabolic state probed. Accordingly, with dynamic nuclear polarization (DNP) and use of (13)C-pyruvate it is now possible to directly study the Warburg Effect through the rate of conversion of (13)C-pyruvate to (13)C-lactate. In this study, we combined it with (18)F-FDG-PET that studies uptake of glucose in the cells. A canine cancer patient with a histology verified local recurrence of a liposarcoma on the right forepaw was imaged using a combined PET/MR clinical scanner. PET was performed as a single-bed, 10 min acquisition, 107 min post injection of 310 MBq (18)F-FDG. (13)C-chemical shift imaging (CSI) was performed just after FDG-PET and 30 s post injection of 23 mL hyperpolarized (13)C-pyruvate. Peak heights of (13)C-pyruvate and (13)C-lactate were quantified using a general linear model. Anatomic (1)H-MRI included axial and coronal T1 vibe, coronal T2-tse and axial T1-tse with fat saturation following gadolinium injection. In the tumor we found clearly increased (13)C-lactate production, which also corresponded to high (18)F-FDG uptake on PET. This is in agreement with the fact that glycolysis and production of lactate are increased in tumor cells compared to normal cells. Yet, most interestingly, also in the muscle of the forepaw of the dog high (18)F-FDG uptake was observed. This was due to activity in these muscles prior to anesthesia, which was not accompanied by a similarly high (13)C-lactate production. Accordingly, this clearly

  4. Prolongation of ERP latency and reaction time (RT) in simultaneous EEG/fMRI data acquisition.

    PubMed

    Chun, Jinsoo; Peltier, Scott J; Yoon, Daehyun; Manschreck, Theo C; Deldin, Patricia J

    2016-08-01

    Recording EEG and fMRI data simultaneously inside a fully-operating scanner has been recognized as a novel approach in human brain research. Studies have demonstrated high concordance between the EEG signals and hemodynamic response. However, a few studies reported altered cognitive process inside the fMRI scanner such as delayed reaction time (RT) and reduced and/or delayed N100 and P300 event-related brain potential (ERP) components. The present study investigated the influence of electromagnetic field (static magnetic field, radio frequency (RF) pulse, and gradient switching) and experimental environment on posterior N100 and P300 ERP components in four different settings with six healthy subjects using a visual oddball task: (1) classic fMRI acquisition inside the scanner (e.g., supine position, mirror glasses for stimulus presentation), (2) standard behavioral experiment outside the scanner (e.g., seated position, keyboard response), (3) controlled fMRI acquisition inside the scanner (e.g., organic light-emitting diode (OLED) goggles for stimulus presentation) inside; and (4) modified behavioral experiment outside the scanner (e.g., supine position, OLED goggles). The study findings indicated that the experimental environment in simultaneous EEG/fMRI acquisition could substantially delay N1P, P300 latency, and RT inside the scanner, and was associated with a reduced N1P amplitude. There was no effect of electromagnetic field in the prolongation of RT, N1P and P300 latency inside the scanner. N1P, but not P300, latency was sensitive to stimulus presentation method inside the scanner. Future simultaneous EEG/fMRI data collection should consider experimental environment in both design and analysis. Copyright © 2016 Elsevier B.V. All rights reserved.

  5. Environment-responsive Nanophores for Therapy and Treatment Monitoring via Molecular MRI Quenching

    PubMed Central

    Kaittanis, Charalambos; Shaffer, Travis M.; Ogirala, Anuja; Santra, Santimukul; Perez, J. Manuel; Chiosis, Gabriela; Li, Yueming; Josephson, Lee; Grimm, Jan

    2014-01-01

    The effective delivery of therapeutics to disease sites significantly contributes to drug efficacy, toxicity and clearance. Here we demonstrate that clinically approved iron oxide nanoparticles (Ferumoxytol) can be utilized to carry one or multiple drugs. These so called ‘nanophores’ retain their cargo within their polymeric coating through weak electrostatic interactions and release it in slightly acidic conditions (pH 6.8 and below). The loading of drugs increases the nanophores’ transverse T2 and longitudinal T1 NMR proton relaxation times, which is proportional to amount of carried cargo. Chemotherapy with translational nanophores is more effective than the free drug in vitro and in vivo, without subjecting the drugs or the carrier nanoparticle to any chemical modification. Evaluation of cargo incorporation and payload levels in vitro and in vivo can be assessed via benchtop magnetic relaxometers, common NMR instruments or MRI scanners. PMID:24594970

  6. Low-Cost High-Performance MRI

    PubMed Central

    Sarracanie, Mathieu; LaPierre, Cristen D.; Salameh, Najat; Waddington, David E. J.; Witzel, Thomas; Rosen, Matthew S.

    2015-01-01

    Magnetic Resonance Imaging (MRI) is unparalleled in its ability to visualize anatomical structure and function non-invasively with high spatial and temporal resolution. Yet to overcome the low sensitivity inherent in inductive detection of weakly polarized nuclear spins, the vast majority of clinical MRI scanners employ superconducting magnets producing very high magnetic fields. Commonly found at 1.5–3 tesla (T), these powerful magnets are massive and have very strict infrastructure demands that preclude operation in many environments. MRI scanners are costly to purchase, site, and maintain, with the purchase price approaching $1 M per tesla (T) of magnetic field. We present here a remarkably simple, non-cryogenic approach to high-performance human MRI at ultra-low magnetic field, whereby modern under-sampling strategies are combined with fully-refocused dynamic spin control using steady-state free precession techniques. At 6.5 mT (more than 450 times lower than clinical MRI scanners) we demonstrate (2.5 × 3.5 × 8.5) mm3 imaging resolution in the living human brain using a simple, open-geometry electromagnet, with 3D image acquisition over the entire brain in 6 minutes. We contend that these practical ultra-low magnetic field implementations of MRI (<10 mT) will complement traditional MRI, providing clinically relevant images and setting new standards for affordable (<$50,000) and robust portable devices. PMID:26469756

  7. Low-Cost High-Performance MRI

    NASA Astrophysics Data System (ADS)

    Sarracanie, Mathieu; Lapierre, Cristen D.; Salameh, Najat; Waddington, David E. J.; Witzel, Thomas; Rosen, Matthew S.

    2015-10-01

    Magnetic Resonance Imaging (MRI) is unparalleled in its ability to visualize anatomical structure and function non-invasively with high spatial and temporal resolution. Yet to overcome the low sensitivity inherent in inductive detection of weakly polarized nuclear spins, the vast majority of clinical MRI scanners employ superconducting magnets producing very high magnetic fields. Commonly found at 1.5-3 tesla (T), these powerful magnets are massive and have very strict infrastructure demands that preclude operation in many environments. MRI scanners are costly to purchase, site, and maintain, with the purchase price approaching $1 M per tesla (T) of magnetic field. We present here a remarkably simple, non-cryogenic approach to high-performance human MRI at ultra-low magnetic field, whereby modern under-sampling strategies are combined with fully-refocused dynamic spin control using steady-state free precession techniques. At 6.5 mT (more than 450 times lower than clinical MRI scanners) we demonstrate (2.5 × 3.5 × 8.5) mm3 imaging resolution in the living human brain using a simple, open-geometry electromagnet, with 3D image acquisition over the entire brain in 6 minutes. We contend that these practical ultra-low magnetic field implementations of MRI (<10 mT) will complement traditional MRI, providing clinically relevant images and setting new standards for affordable (<$50,000) and robust portable devices.

  8. Dynamic contrast-enhanced susceptibility-weighted perfusion MRI (DSC-MRI) in a glioma model of the rat brain using a conventional receive-only surface coil with a inner diameter of 47 mm at a clinical 1.5 T scanner.

    PubMed

    Ulmer, Stephan; Reeh, Matthias; Krause, Joerg; Herdegen, Thomas; Heldt-Feindt, Janka; Jansen, Olav; Rohr, Axel

    2008-07-30

    Magnetic resonance (MR) imaging in animal models is usually performed in expensive dedicated small bore animal scanners of limited availability. In the present study a standard clinical 1.5 T MR scanner was used for morphometric and dynamic contrast-enhanced susceptibility-weighted MR imaging (DSC-MRI) of a glioma model of the rat brain. Ten male Wistar rats were examined with coronal T2-weighted, and T1-weighted images (matrix 128 x 128, FOV 64 mm) after implantation of an intracerebral tumor xenografts (C6) using a conventional surface coil. For DSC-MRI a T2*-weighted sequence (TR/TE=30/14 ms, matrix 64 x 64, FOV 90 mm; slice thickness of 1.5mm) was performed. Regions of interest were defined within the tumor and the non-affected contralateral hemisphere and the mean transit time (MTT) was determined. Tumor dimensions in MR predicted well its real size as proven by histology. The MTT of contrast agent passing through the brain was significantly decelerated in the tumor compared to the unaffected hemisphere (p<0.001, paired t-test), which is most likely due to the leakage of contrast agent through the disrupted blood brain barrier. This setup offers advanced MR imaging of small animals without the need for dedicated animal scanners or dedicated custom-made coils.

  9. Self-regulation strategy, feedback timing and hemodynamic properties modulate learning in a simulated fMRI neurofeedback environment.

    PubMed

    Oblak, Ethan F; Lewis-Peacock, Jarrod A; Sulzer, James S

    2017-07-01

    Direct manipulation of brain activity can be used to investigate causal brain-behavior relationships. Current noninvasive neural stimulation techniques are too coarse to manipulate behaviors that correlate with fine-grained spatial patterns recorded by fMRI. However, these activity patterns can be manipulated by having people learn to self-regulate their own recorded neural activity. This technique, known as fMRI neurofeedback, faces challenges as many participants are unable to self-regulate. The causes of this non-responder effect are not well understood due to the cost and complexity of such investigation in the MRI scanner. Here, we investigated the temporal dynamics of the hemodynamic response measured by fMRI as a potential cause of the non-responder effect. Learning to self-regulate the hemodynamic response involves a difficult temporal credit-assignment problem because this signal is both delayed and blurred over time. Two factors critical to this problem are the prescribed self-regulation strategy (cognitive or automatic) and feedback timing (continuous or intermittent). Here, we sought to evaluate how these factors interact with the temporal dynamics of fMRI without using the MRI scanner. We first examined the role of cognitive strategies by having participants learn to regulate a simulated neurofeedback signal using a unidimensional strategy: pressing one of two buttons to rotate a visual grating that stimulates a model of visual cortex. Under these conditions, continuous feedback led to faster regulation compared to intermittent feedback. Yet, since many neurofeedback studies prescribe implicit self-regulation strategies, we created a computational model of automatic reward-based learning to examine whether this result held true for automatic processing. When feedback was delayed and blurred based on the hemodynamics of fMRI, this model learned more reliably from intermittent feedback compared to continuous feedback. These results suggest that different

  10. Self-regulation strategy, feedback timing and hemodynamic properties modulate learning in a simulated fMRI neurofeedback environment

    PubMed Central

    Sulzer, James S.

    2017-01-01

    Direct manipulation of brain activity can be used to investigate causal brain-behavior relationships. Current noninvasive neural stimulation techniques are too coarse to manipulate behaviors that correlate with fine-grained spatial patterns recorded by fMRI. However, these activity patterns can be manipulated by having people learn to self-regulate their own recorded neural activity. This technique, known as fMRI neurofeedback, faces challenges as many participants are unable to self-regulate. The causes of this non-responder effect are not well understood due to the cost and complexity of such investigation in the MRI scanner. Here, we investigated the temporal dynamics of the hemodynamic response measured by fMRI as a potential cause of the non-responder effect. Learning to self-regulate the hemodynamic response involves a difficult temporal credit-assignment problem because this signal is both delayed and blurred over time. Two factors critical to this problem are the prescribed self-regulation strategy (cognitive or automatic) and feedback timing (continuous or intermittent). Here, we sought to evaluate how these factors interact with the temporal dynamics of fMRI without using the MRI scanner. We first examined the role of cognitive strategies by having participants learn to regulate a simulated neurofeedback signal using a unidimensional strategy: pressing one of two buttons to rotate a visual grating that stimulates a model of visual cortex. Under these conditions, continuous feedback led to faster regulation compared to intermittent feedback. Yet, since many neurofeedback studies prescribe implicit self-regulation strategies, we created a computational model of automatic reward-based learning to examine whether this result held true for automatic processing. When feedback was delayed and blurred based on the hemodynamics of fMRI, this model learned more reliably from intermittent feedback compared to continuous feedback. These results suggest that different

  11. Cortical and subcortical mapping of language areas: correlation of functional MRI and tractography in a 3T scanner with intraoperative cortical and subcortical stimulation in patients with brain tumors located in eloquent areas.

    PubMed

    Jiménez de la Peña, M; Gil Robles, S; Recio Rodríguez, M; Ruiz Ocaña, C; Martínez de Vega, V

    2013-01-01

    To describe the detection of cortical areas and subcortical pathways involved in language observed in MRI activation studies and tractography in a 3T MRI scanner and to correlate the findings of these functional studies with direct intraoperative cortical and subcortical stimulation. We present a series of 14 patients with focal brain tumors adjacent to eloquent brain areas. All patients underwent neuropsychological evaluation before and after surgery. All patients underwent MRI examination including structural sequences, perfusion imaging, spectroscopy, functional imaging to determine activation of motor and language areas, and 3D tractography. All patients underwent cortical mapping through cortical and subcortical stimulation during the operation to resect the tumor. Postoperative follow-up studies were done 24 hours after surgery. The correlation of motor function and of the corticospinal tract determined by functional MRI and tractography with intraoperative mapping of cortical and subcortical motor areas was complete. The eloquent brain areas of language expression and reception were strongly correlated with intraoperative cortical mapping in all but two cases (a high grade infiltrating glioma and a low grade glioma located in the frontal lobe). 3D tractography identified the arcuate fasciculus, the lateral part of the superior longitudinal fasciculus, the subcallosal fasciculus, the inferior fronto-occipital fasciculus, and the optic radiations, which made it possible to mark the limits of the resection. The correlation with the subcortical mapping of the anatomic arrangement of the fasciculi with respect to the lesions was complete. The best treatment for brain tumors is maximum resection without associated deficits, so high quality functional studies are necessary for preoperative planning. Copyright © 2011 SERAM. Published by Elsevier Espana. All rights reserved.

  12. Phantom haptic device upgrade for use in fMRI.

    PubMed

    Hribar, Ales; Koritnik, Blaz; Munih, Marko

    2009-06-01

    This paper presents an upgrade of a Phantom Premium 1.5 haptic device for use within a functional magnetic resonance imaging (fMRI) environment. A special mechanical extension that allows the haptic device to operate at a safe distance from the high-density magnetic field of an fMRI scanner has been developed. Extended haptic system was subjected to a series of tests to confirm electromagnetic compatibility with the fMRI scanner, for which key results are presented. With this fMRI compatible haptic platform a human brain activation during controlled upper limb movements can be studied. A simple virtual environment reaching task was programmed to study brain motor control functions. At the end preliminary results of an ongoing neurophysiological study are presented.

  13. Recording event-related activity under hostile magnetic resonance environment: Is multimodal EEG/ERP-MRI recording possible?

    PubMed

    Karakaş, H M; Karakaş, S; Ozkan Ceylan, A; Tali, E T

    2009-08-01

    Event-related potentials (ERPs) have high temporal resolution, but insufficient spatial resolution; the converse is true for the functional imaging techniques. The purpose of the study was to test the utility of a multimodal EEG/ERP-MRI technique which combines electroencephalography (EEG) and magnetic resonance imaging (MRI) for a simultaneously high temporal and spatial resolution. The sample consisted of 32 healthy young adults of both sexes. Auditory stimuli were delivered according to the active and passive oddball paradigms in the MRI environment (MRI-e) and in the standard conditions of the electrophysiology laboratory environment (Lab-e). Tasks were presented in a fixed order. Participants were exposed to the recording environments in a counterbalanced order. EEG data were preprocessed for MRI-related artifacts. Source localization was made using a current density reconstruction technique. The ERP waveforms for the MRI-e were morphologically similar to those for the Lab-e. The effect of the recording environment, experimental paradigm and electrode location were analyzed using a 2x2x3 analysis of variance for repeated measures. The ERP components in the two environments showed parametric variations and characteristic topographical distributions. The calculated sources were in line with the related literature. The findings indicated effortful cognitive processing in MRI-e. The study provided preliminary data on the feasibility of the multimodal EEG/ERP-MRI technique. It also indicated lines of research that are to be pursued for a decisive testing of this technique and its implementation to clinical practice.

  14. Interactive 3-dimensional segmentation of MRI data in personal computer environment.

    PubMed

    Yoo, S S; Lee, C U; Choi, B G; Saiviroonporn, P

    2001-11-15

    We describe a method of interactive three-dimensional segmentation and visualization for anatomical magnetic resonance imaging (MRI) data in a personal computer environment. The visual feedback necessary during 3-D segmentation was provided by a ray casting algorithm, which was designed to allow users to interactively decide the visualization quality depending on the task-requirement. Structures such as gray matter, white matter, and facial skin from T1-weighted high-resolution MRI data were segmented and later visualized with surface rendering. Personal computers with central processing unit (CPU) speeds of 266, 400, and 700 MHz, were used for the implementation. The 3-D visualization upon each execution of the segmentation operation was achieved in the order of 2 s with a 700 MHz CPU. Our results suggest that 3-D volume segmentation with semi real-time visual feedback could be effectively implemented in a PC environment without the need for dedicated graphics processing hardware.

  15. MRI renaissance.

    PubMed

    Hensley, S

    1997-12-01

    A few years ago, magnetic resonance imaging was healthcare's version of a foreign sports car-flashy, expensive and impractical. Now, after years in the doldrums, sales of MRI systems are roaring back. An aging fleet of MRI scanners due for replacement and a hearty increase in doctors' use of the versatile imaging tools are combining to fuel the surge in demand, vendors and customers say.

  16. Dynamic Contrast-Enhanced MRI Parameters as Biomarkers in Assessing Head and Neck Lesions After Chemoradiotherapy Using a Wide-Bore 3 Tesla Scanner.

    PubMed

    Lerant, Gergely; Sarkozy, Peter; Takacsi-Nagy, Zoltan; Polony, Gabor; Tamas, Laszlo; Toth, Erika; Boer, Andras; Javor, Laszlo; Godeny, Maria

    2015-09-01

    Pilot studies have shown promising results in characterizing head and neck tumors (HNT) using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI), differentiating between malignant and benign lesions and evaluating changes in response to chemoradiotherapy (CRT). Our aim was to find DCE-MRI parameters, biomarkers in evaluating the post-CRT status. Two hundred and five patients with head and neck lesions were examined with DCE-MRI sequences. The time intensity curves (TIC) were extracted and processed to acquire time-to-peak (TTP), relative maximum enhancement (RME), relative wash-out (RWO), and two new parameters attack and decay. These parameters were analyzed using univariate tests in SPSS (Statistical Package for the Social Sciences, version 17, SPSS Inc. Chicago, USA) to identify parameters that could be used to infer tumor malignancy and post-CRT changes. Multiple parameters of curve characteristics were significantly different between malignant tumors after CRT (MACRT) and changes caused by CRT. The best-performing biomarkers were the attack and the decay. We also found multiple significant (p < 0.05) parameters for both the benign and malignant status as well as pre- and post-CRT status. Our large cohort of data supports the increasing role of DCE-MRI in HNT differentiation, particularly for the assessment of post-CRT status along with accurate morphological imaging.

  17. Redox-Triggered Self-Assembly of Gadolinium-Based MRI Probes for Sensing Reducing Environment

    PubMed Central

    2014-01-01

    Controlled self-assembly of small molecule gadolinium (Gd) complexes into nanoparticles (GdNPs) is emerging as an effective approach to design activatable magnetic resonance imaging (MRI) probes and amplify the r1 relaxivity. Herein, we employ a reduction-controlled macrocyclization reaction and self-assembly to develop a redox activated Gd-based MRI probe for sensing a reducing environment. Upon disulfide reduction at physiological conditions, an acyclic contrast agent 1 containing dual Gd-chelates undergoes intramolecular macrocyclization to form rigid and hydrophobic macrocycles, which subsequently self-assemble into GdNPs, resulting in a ∼60% increase in r1 relaxivity at 0.5 T. Probe 1 has high r1 relaxivity (up to 34.2 mM–1 s–1 per molecule at 0.5 T) upon activation, and also shows a high sensitivity and specificity for MR detection of thiol-containing biomolecules. PMID:24992373

  18. MR-Guided Freehand Biopsy of Liver Lesions With Fast Continuous Imaging Using a 1.0-T Open MRI Scanner: Experience in 50 Patients

    SciTech Connect

    Fischbach, Frank; Bunke, Juergen; Thormann, Markus; Gaffke, Gunnar; Jungnickel, Kerstin; Smink, Jouke; Ricke, Jens

    2011-02-15

    The purpose of this study was to assess a new open system with a field-strength of 1.0 T for the feasibility of liver biopsy using the freehand technique with fast continuous imaging. Fifty patients with focal liver lesions measuring 5 to 30 mm in diameter were included in the study. Guidance and monitoring was performed using a 1.0-T open magnetic resonance (MR) scanner (Panorama HFO; Philips Healthcare, Best, The Netherlands). With fast continuous imaging using a T1-weighted (T1W) gradient echo (GRE) sequence after administration of gadolinium (Gd)-EOB-DTPA, the needle was placed into the lesion. An interface for interactive dynamic viewing in two perpendicular planes prevented needle deviations T2-weighted turbo spin echo (TSE) fat-suppressed sequence was added to rule out postinterventional hematoma or biloma. All lesions were visible on the interventional images. Biopsy was technically successful, and solid specimens were obtained in all cases. Forty-six patients showed a histopathologic pattern other than native liver tissue, thus confirming correct position of the needle. Time between determination of the lesion and performance of the control scan was on average 18 min. No major complications were recorded. MR guidance with the new 1-T open system must be considered an attractive alternative for liver punction. An interface for dynamic imaging of needle guidance and T1W-GRE imaging with administration of Gd-EOB-DTPA for contrast enhancement allows the pinpoint puncture of liver lesions.

  19. Vascular thoracic outlet syndrome: protocol design and diagnostic value of contrast-enhanced 3D MR angiography and equilibrium phase imaging on 1.5- and 3-T MRI scanners.

    PubMed

    Ersoy, Hale; Steigner, Michael L; Coyner, Karl B; Gerhard-Herman, Marie D; Rybicki, Frank J; Bueno, Raphael; Nguyen, Louis L

    2012-05-01

    The purpose of this article is to evaluate the efficiency and reproducibility of a contrast-enhanced 3D MR angiography (MRA) protocol, using the provocative arm position on 1.5- and 3-T MRI scanners, and to determine the frequency and distribution of vascular compression and vascular complications in the thoracic outlet. Seventy-eight consecutive patients with clinically suspected thoracic outlet syndrome (TOS) were included in the study. Two radiologists independently analyzed all eligible vessel segments, and interobserver agreement was determined using kappa statistics. The distribution of vascular compression with regard to the clinical presentation at referral was also analyzed. A venous component, which presented with mainly venous symptoms and findings, was confirmed in 85% of the subjects. An arterial component, which presented with clinical symptoms and findings of vascular TOS syndrome, was seen in 82% of the subjects. The vascular component of TOS, which presented with mainly neurogenic or indeterminate symptoms or findings, was excluded in 61% of the subjects. Contrast-enhanced 3D MRA using provocative arm positioning allows excellent imaging of the arteries and veins on both sides and thus provides a noninvasive imaging alternative to digital subtraction angiography in patients with suspected vascular TOS. Contrast-enhanced 3D MRA is also an ideal imaging modality for postsurgical follow-up for identifying restenosis or residual vascular compression. However, all imaging studies, including the contrast-enhanced 3D MRA protocol described here, should be treated as complementary tests for the diagnosis of TOS.

  20. Exploratory data analysis for robot perception of room environments by means of an in-air sonar scanner.

    PubMed

    Giannoccaro, Nicola Ivan; Spedicato, Luigi

    2013-08-01

    In this paper, the authors have developed a new method for reconstructing the boundary walls of a room environment by using a mechatronic device consisting of four ultrasonic sensors rotated by a servo modular actuator. This scanning system allows to measure the times of flight in each motor position so as to explore the surrounding space detecting reflections from the boundary walls and from other static obstacles. In addition to undesired reflections, due to non-target obstacles interposed between the sensors and the target surfaces, several spurious times are observed at the corners because of multiple reflections. The Fuzzy C-Means (FCM) algorithm is used for partitioning the obtained dataset in five clusters and some considerations on the output signal energy permit to select the two subsets concerned with multipath echoes. Each remaining cluster is associated to a set of three-dimensional points by considering the directivity of the wide beam propagated. In order to discard the observations that are numerically distant from the confidence data, the three sets are filtered by means of an ellipsoid defined by the Principal Component Analysis (PCA). The best-fit planes are obtained by testing the eigenvalues and relating eigenvectors of the covariance matrix of each filtered set. Several tests are shown and discussed for appreciating the effectiveness of the described approach and they are aimed at making a robot aware of its environment.

  1. A modular, computer-controlled system for olfactory stimulation in the MRI environment.

    PubMed

    Andrieu, Patrice; Bonnans, Vincent; Meneses, Jaime; Millot, Jean-Louis; Moulin, Thierry; Gharbi, Tijani

    2014-03-01

    Although the cerebral networks involved in sensory perception are of general interest in neuroscience, registration of the effects of olfactory stimulation, especially in a magnetic resonance imaging (MRI) environment, presents particular problems and constraints. This article presents details of a reliable and portable system for olfactory stimulation that is modular in design and based on microcontroller technology. It has the following characteristics: (1) It is under software control; (2) the presentation of olfactory stimulation can be synchronized with respiration; (3) it can be manually controlled; and (4) it is fully compatible with an MRI environment. The principle underlying this system is to direct an odor to the subject's nostrils by switching airflow to different odor diffusers. The characteristics of this system were established using (1) ultraviolet (UV) spectroscopy, to measure its response time, and (2) gas chromatography, to measure the repeatability of odor presentation in terms of gas concentration. A response time of 200 ± 25 ms was obtained for the system, and the standard deviations of the gas concentration delivered during stimulation ranged from 1.5% to 22%, depending on the odor, the airflow, and the dilution of the odor used. Since it is portable, controlled by software, and reliable, on the basis of the results we obtained, this system will lend itself to a wide range of applications in olfactory neuroscience.

  2. Multispectral scanner optical system

    NASA Technical Reports Server (NTRS)

    Stokes, R. C.; Koch, N. G. (Inventor)

    1980-01-01

    An optical system for use in a multispectral scanner of the type used in video imaging devices is disclosed. Electromagnetic radiation reflected by a rotating scan mirror is focused by a concave primary telescope mirror and collimated by a second concave mirror. The collimated beam is split by a dichroic filter which transmits radiant energy in the infrared spectrum and reflects visible and near infrared energy. The long wavelength beam is filtered and focused on an infrared detector positioned in a cryogenic environment. The short wavelength beam is dispersed by a pair of prisms, then projected on an array of detectors also mounted in a cryogenic environment and oriented at an angle relative to the optical path of the dispersed short wavelength beam.

  3. Integrating a MRI scanner with a 6 MV radiotherapy accelerator: impact of the surface orientation on the entrance and exit dose due to the transverse magnetic field.

    PubMed

    Raaijmakers, A J E; Raaymakers, B W; van der Meer, S; Lagendijk, J J W

    2007-02-21

    At the UMC Utrecht, in collaboration with Elekta and Philips Research Hamburg, we are developing a radiotherapy accelerator with integrated MRI functionality. The radiation dose will be delivered in the presence of a lateral 1.5 T field. Although the photon beam is not affected by the magnetic field, the actual dose deposition is done by a cascade of secondary electrons and these electrons are affected by the Lorentz force. The magnetic field causes a reduced build-up distance: because the trajectory of the electrons between collisions is curved, the entrance depth in tissue decreases. Also, at tissue-air interfaces an increased dose occurs due to the so-called electron return effect (ERE): electrons leaving tissue will describe a circular path in air and re-enter the tissue yielding a local dose increase. In this paper the impact of a 1.5 T magnetic field on both the build-up distance and the dose increase due to the ERE will be investigated as a function of the angle between the surface and the incident beam. Monte Carlo simulations demonstrate that in the presence of a 1.5 T magnetic field, the surface dose, the build-up distance and the exit dose depend more heavily on the surface orientation than in the case without magnetic field. This is caused by the asymmetrical pointspread kernel in the presence of 1.5 T and the directional behaviour of the re-entering electrons. Simulations on geometrical phantoms show that ERE dose increase at air cavities can be avoided using opposing beams, also when the air-tissue boundary is not perpendicular to the beam. For the more general case in patient anatomies, more problems may arise. Future work will address the possibilities and limitations of opposing beams in combination with IMRT in a magnetic field.

  4. Integrating a MRI scanner with a 6 MV radiotherapy accelerator: impact of the surface orientation on the entrance and exit dose due to the transverse magnetic field

    NASA Astrophysics Data System (ADS)

    Raaijmakers, A. J. E.; Raaymakers, B. W.; van der Meer, S.; Lagendijk, J. J. W.

    2007-02-01

    At the UMC Utrecht, in collaboration with Elekta and Philips Research Hamburg, we are developing a radiotherapy accelerator with integrated MRI functionality. The radiation dose will be delivered in the presence of a lateral 1.5 T field. Although the photon beam is not affected by the magnetic field, the actual dose deposition is done by a cascade of secondary electrons and these electrons are affected by the Lorentz force. The magnetic field causes a reduced build-up distance: because the trajectory of the electrons between collisions is curved, the entrance depth in tissue decreases. Also, at tissue-air interfaces an increased dose occurs due to the so-called electron return effect (ERE): electrons leaving tissue will describe a circular path in air and re-enter the tissue yielding a local dose increase. In this paper the impact of a 1.5 T magnetic field on both the build-up distance and the dose increase due to the ERE will be investigated as a function of the angle between the surface and the incident beam. Monte Carlo simulations demonstrate that in the presence of a 1.5 T magnetic field, the surface dose, the build-up distance and the exit dose depend more heavily on the surface orientation than in the case without magnetic field. This is caused by the asymmetrical pointspread kernel in the presence of 1.5 T and the directional behaviour of the re-entering electrons. Simulations on geometrical phantoms show that ERE dose increase at air cavities can be avoided using opposing beams, also when the air-tissue boundary is not perpendicular to the beam. For the more general case in patient anatomies, more problems may arise. Future work will address the possibilities and limitations of opposing beams in combination with IMRT in a magnetic field.

  5. Accurately decoding visual information from fMRI data obtained in a realistic virtual environment

    PubMed Central

    Floren, Andrew; Naylor, Bruce; Miikkulainen, Risto; Ress, David

    2015-01-01

    Three-dimensional interactive virtual environments (VEs) are a powerful tool for brain-imaging based cognitive neuroscience that are presently under-utilized. This paper presents machine-learning based methods for identifying brain states induced by realistic VEs with improved accuracy as well as the capability for mapping their spatial topography on the neocortex. VEs provide the ability to study the brain under conditions closer to the environment in which humans evolved, and thus to probe deeper into the complexities of human cognition. As a test case, we designed a stimulus to reflect a military combat situation in the Middle East, motivated by the potential of using real-time functional magnetic resonance imaging (fMRI) in the treatment of post-traumatic stress disorder. Each subject experienced moving through the virtual town where they encountered 1–6 animated combatants at different locations, while fMRI data was collected. To analyze the data from what is, compared to most studies, more complex and less controlled stimuli, we employed statistical machine learning in the form of Multi-Voxel Pattern Analysis (MVPA) with special attention given to artificial Neural Networks (NN). Extensions to NN that exploit the block structure of the stimulus were developed to improve the accuracy of the classification, achieving performances from 58 to 93% (chance was 16.7%) with six subjects. This demonstrates that MVPA can decode a complex cognitive state, viewing a number of characters, in a dynamic virtual environment. To better understand the source of this information in the brain, a novel form of sensitivity analysis was developed to use NN to quantify the degree to which each voxel contributed to classification. Compared with maps produced by general linear models and the searchlight approach, these sensitivity maps revealed a more diverse pattern of information relevant to the classification of cognitive state. PMID:26106315

  6. Haptic fMRI: combining functional neuroimaging with haptics for studying the brain's motor control representation.

    PubMed

    Menon, Samir; Brantner, Gerald; Aholt, Chris; Kay, Kendrick; Khatib, Oussama

    2013-01-01

    A challenging problem in motor control neuroimaging studies is the inability to perform complex human motor tasks given the Magnetic Resonance Imaging (MRI) scanner's disruptive magnetic fields and confined workspace. In this paper, we propose a novel experimental platform that combines Functional MRI (fMRI) neuroimaging, haptic virtual simulation environments, and an fMRI-compatible haptic device for real-time haptic interaction across the scanner workspace (above torso ∼ .65×.40×.20m(3)). We implement this Haptic fMRI platform with a novel haptic device, the Haptic fMRI Interface (HFI), and demonstrate its suitability for motor neuroimaging studies. HFI has three degrees-of-freedom (DOF), uses electromagnetic motors to enable high-fidelity haptic rendering (>350Hz), integrates radio frequency (RF) shields to prevent electromagnetic interference with fMRI (temporal SNR >100), and is kinematically designed to minimize currents induced by the MRI scanner's magnetic field during motor displacement (<2cm). HFI possesses uniform inertial and force transmission properties across the workspace, and has low friction (.05-.30N). HFI's RF noise levels, in addition, are within a 3 Tesla fMRI scanner's baseline noise variation (∼.85±.1%). Finally, HFI is haptically transparent and does not interfere with human motor tasks (tested for .4m reaches). By allowing fMRI experiments involving complex three-dimensional manipulation with haptic interaction, Haptic fMRI enables-for the first time-non-invasive neuroscience experiments involving interactive motor tasks, object manipulation, tactile perception, and visuo-motor integration.

  7. Measuring adult attachment representation in an fMRI environment: concepts and assessment.

    PubMed

    Buchheim, Anna; George, Carol; Kachele, Horst; Erk, Susanne; Walter, Henrik

    2006-01-01

    Human attachment is defined as a biologically based behavioral system that influences motivational, cognitive, emotional, and memory processes with respect to intimate relationships (parents, life partner, own children). Recent neurobiological studies in this field have in common that they investigated social relationships by examining fMRI neuroimaging patterns while individuals viewed pictures of their beloved relationship partner versus friends, acquaintances, strangers, or mothers' responses to their young children. The researchers showed that the neural underpinnings of these unique intimate emotional states are linked to functionally specialized areas in the brain. Conceptualizing this work from a behavioral systems-attachment theory perspective, these studies did not directly address the subject's attachment representational system. Traditional attachment theory and research has been built on the analysis of attachment narratives, called 'attachment representation'. The Adult Attachment Projective developed by George and West in 2001 is a set of attachment-based schematic pictures. It is constructed to increasingly activate the participant's attachment system in the course of the task, that is, by the introduction of increasingly stressful attachment scenes concluding with pictures of individuals facing death and potential abuse alone. The attachment patterns are evaluated based on individuals' overall verbal response to the picture set. This paper proposes that the AAP is a fruitful measure to use in an fMRI environment to examine brain activation patterns in adults while they are speaking overtly about attachment stories in a standardized setting.

  8. Intraoperative magnetic resonance imaging with the magnetom open scanner: concepts, neurosurgical indications, and procedures: a preliminary report.

    PubMed

    Steinmeier, R; Fahlbusch, R; Ganslandt, O; Nimsky, C; Buchfelder, M; Kaus, M; Heigl, T; Lenz, G; Kuth, R; Huk, W

    1998-10-01

    Intraoperative magnetic resonance imaging (MRI) is now available with the General Electric MRI system for dedicated intraoperative use. Alternatively, non-dedicated MRI systems require fewer specific adaptations of instrumentation and surgical techniques. In this report, clinical experiences with such a system are presented. All patients were surgically treated in a "twin operating theater," consisting of a conventional operating theater with complete neuronavigation equipment (StealthStation and MKM), which allowed surgery with magnetically incompatible instruments, conventional instrumentation and operating microscope, and a radiofrequency-shielded operating room designed for use with an intraoperative MRI scanner (Magnetom Open; Siemens AG, Erlangen, Germany). The Magnetom Open is a 0.2-T MRI scanner with a resistive magnet and specific adaptations that are necessary to integrate the scanner into the surgical environment. The operating theaters lie close together, and patients can be intraoperatively transported from one room to the other. This retrospective analysis includes 55 patients with cerebral lesions, all of whom were surgically treated between March 1996 and September 1997. Thirty-one patients with supratentorial tumors were surgically treated (with navigational guidance) in the conventional operating room, with intraoperative MRI for resection control. For 5 of these 31 patients, intraoperative resection control revealed significant tumor remnants, which led to further tumor resection guided by the information provided by intraoperative MRI. Intraoperative MRI resection control was performed in 18 transsphenoidal operations. In cases with suspected tumor remnants, the surgeon reexplored the sellar region; additional tumor tissue was removed in three of five cases. Follow-up scans were obtained for all patients 1 week and 2 to 3 months after surgery. For 14 of the 18 patients, the images obtained intraoperatively were comparable to those obtained after

  9. MRI simulator: a teaching tool for radiology

    NASA Astrophysics Data System (ADS)

    Rundle, Debra A.; Kishore, Sheel; Seshadri, Sridhar B.; Wehrli, Felix W.

    1990-08-01

    The increasing use of magnetic resonance imaging (MRI) as a clinical modality has put an enormous burden on medical institutions to cost-effectively teach Mill scanning techniques to technologists and physicians. Since MRI scanner time is a scarce resource, it would be ideal if the teaching could be effectively performed off-line. In order to meet this goal, the Radiology Department has designed and developed a Magnetic Resonance Imaging Simulator. The Simulator in its current implementation mimics the General Electric Signa scanner's user-interface for image acquisition. The design is general enough to be applied to other MRI scanners. One unique feature of the simulator is its incorporation of an image-synthesis module which permits the user to derive images for any arbitrary combination of pulsing parameters for spin-echo, gradient-echo, and inversion recovery pulse sequences. These images are computed in five seconds. The development platform chosen is a standard Apple Macintosh-Il computer with no specialized hardware peripherals. The user-interface is implemented in HyperCard. All other software development including synthesis and display functions are implemented under the MPW 'C' environment. The scan parameters, demographics and images are tracked using an Oracle database. Images are currently stored on magnetic disk but could be stored on optical media with minimal effort.

  10. RPV-800 Infrared Line Scanner

    NASA Astrophysics Data System (ADS)

    Stageberg, Dale L.

    1993-12-01

    This paper describes the RPV-800 Infrared Line Scanner, recently developed system that uses a unique split-image gallium arsenide scan element and production DoD common modules. This design reduces system size and weight, eliminates field optical alignments and contributes to a high predicted system mean time between failure. Small size, reduced power and lower life-cycle cost are critical decision elements in the unmanned aerial vehicle environment.

  11. Focusing laser scanner

    NASA Technical Reports Server (NTRS)

    Callen, W. R.; Weaver, J. E.

    1979-01-01

    Economical laser scanner assembled from commercially available components, modulates and scans focused laser beam over area up to 5.1 by 5.1 cm. Scanner gives resolution comparable to that of conventional television. Device is highly applicable to area of analog and digital storage and retrieval.

  12. Polygon scanners revisited

    NASA Astrophysics Data System (ADS)

    Sweeney, Michael N.

    1997-07-01

    The demands for increased throughput, pixel density, and format size in the laser beam imaging field continue to challenge opto-mechanical scanning products and the electronics that drive them. The polygon line scanner has superior scan rate and scan efficiency among candidate mechanical scanners but, historically, has had inferior cross- scan and in-scan accuracy. To date, due to cost considerations, these limitations have excluded the polygon scanner from practical use in high resolution, flat field, large format commercial applications. This paper illustrates the tradeoffs among the three most common mechanical scanners; single reflection rotary scanner, resonant galvanometric scanner, and polygon scanner. The purpose of this discussion is to illustrate that the polygon scanner holds the best promise of advancing the state-of-art in reasonable cost, large format, high resolution, flat field imaging once the problems of cross-scan and in-scan errors are reconciled in the design of the system. Also introduced is a polygon scanning system that fulfills the requirements of an advanced flat field, large format line imaging platform.

  13. MRI-Safe Robot for Endorectal Prostate Biopsy

    PubMed Central

    Stoianovici, Dan; Kim, Chunwoo; Srimathveeravalli, Govindarajan; Sebrecht, Peter; Petrisor, Doru; Coleman, Jonathan; Solomon, Stephen B.; Hricak, Hedvig

    2014-01-01

    This paper reports the development of an MRI-Safe robot for direct (interventional) MRI-guided endorectal prostate biopsy. The robot is constructed of nonmagnetic and electrically nonconductive materials, and is electricity free, using pneumatic actuation and optical sensors. Targeting biopsy lesions of MRI abnormality presents substantial clinical potential for the management of prostate cancer. The paper describes MRI-Safe requirements, presents the kinematic architecture, design and construction of the robot, and a comprehensive set of preclinical tests for MRI compatibility and needle targeting accuracy. The robot has a compact and simple 3 degree-of-freedom (DoF) structure, two for orienting a needle-guide and one to preset the depth of needle insertion. The actual insertion is performed manually through the guide and up to the preset depth. To reduce the complexity and size of the robot next to the patient, the depth setting DoF is remote. Experimental results show that the robot is safe to use in any MRI environment (MRI-Safe). Comprehensive MRI tests show that the presence and motion of the robot in the MRI scanner cause virtually no image deterioration or signal to noise ratio (SNR) change. Robot’s accuracy in bench test, CT-guided in-vitro, MRI-guided in-vitro and animal tests are 0.37mm, 1.10mm, 2.09mm, and 2.58mm respectively. These values are acceptable for clinical use. PMID:25378897

  14. Reproducibility of Quantitative Structural and Physiological MRI Measurements

    DTIC Science & Technology

    2017-08-09

    three times over 5 days on a Siemens 3T Verio scanner equipped with a 32-channel phase array coil. Structural (T1, T2-weighted, and diffusion-weighted...in healthy subjects while controlling physiological and technical parameters. Methods: Twenty- five subjects were imaged three times over 5 days on a...environment with a consistently maintained meal time, sleep/wake time, and exercise program. Commencing 7 days prior to the first MRI and continuing

  15. Using Magnetic Resonance Imaging (MRI) to Investigate Scalar Contaminant Dispersion in an Urban Environment

    NASA Astrophysics Data System (ADS)

    Cymerman, Joseph

    2016-11-01

    Research in the past few decades on the dispersion of a scalar contaminant through an urban environment, with testing occurring in multiple cities worldwide, has mostly relied on point measurement systems. These models, which are strongly affected by the orientation of the buildings and environmental conditions, obtain relatively few data points and fail to achieve a robust understanding of the complex flow fields from an experimental perspective. A time-averaged MRI-based experimental measurement of the complete three-dimensional flow field has analyzed an array of buildings at two orientations in fully turbulent flow. The Reynolds number and upstream development match a series of tests conducted by both the ARL Atmospheric Sciences Branch and the Los Alamos National Laboratory for comparison, with several million measurements of each of the three components of the mean velocity across the full field. The water-based experimental measurements allow for the assessment of the geometric dispersion of the streamlines and a comparison with several computational models as a means of validation.

  16. Tunable Resonant Scanners

    NASA Astrophysics Data System (ADS)

    Montagu, Jean I.

    1987-01-01

    The most attractive features of resonant scanners are high reliability and eternal life as well as extremely low wobble and jitter. Power consumption is also low, electronic drive is simple, and the device is capable of handling large beams. All of these features are delivered at a low cost in a small package. The resonant scanner's use in numerous high precision applications, however, has been limited because of the difficulty in controlling its phase and resonant frequency. This paper introduces the concept of tunable/controllable resonant scanners, discusses their features, and offers a number of tuning techniques. It describes two angular scanner designs and presents data on tunable range and life tests. It also reviews applications for these new tunable resonant scanners that preserve the desirable features of earlier models while removing the old problems with synchronization or time base flexibility. The three major types of raster scanning applications where the tunable resonant scanner may be of benefit are: 1. In systems with multiple time bases such as multiple scanner networks or with scanners keyed to a common clock (the line frequency or data source) or a machine with multiple resonant scanners. A typical application is image and text transmission, also a printer with a large data base where a buffer is uneconomical. 2. In systems sharing data processing or laser equipment for reasons of cost or capacity, typically multiple work station manufacturing processes or graphic processes. 3. In systems with extremely precise time bases where the frequency stability of conventional scanners cannot be relied upon.

  17. Resting-State fMRI Activity Predicts Unsupervised Learning and Memory in an Immersive Virtual Reality Environment

    PubMed Central

    Wong, Chi Wah; Olafsson, Valur; Plank, Markus; Snider, Joseph; Halgren, Eric; Poizner, Howard; Liu, Thomas T.

    2014-01-01

    In the real world, learning often proceeds in an unsupervised manner without explicit instructions or feedback. In this study, we employed an experimental paradigm in which subjects explored an immersive virtual reality environment on each of two days. On day 1, subjects implicitly learned the location of 39 objects in an unsupervised fashion. On day 2, the locations of some of the objects were changed, and object location recall performance was assessed and found to vary across subjects. As prior work had shown that functional magnetic resonance imaging (fMRI) measures of resting-state brain activity can predict various measures of brain performance across individuals, we examined whether resting-state fMRI measures could be used to predict object location recall performance. We found a significant correlation between performance and the variability of the resting-state fMRI signal in the basal ganglia, hippocampus, amygdala, thalamus, insula, and regions in the frontal and temporal lobes, regions important for spatial exploration, learning, memory, and decision making. In addition, performance was significantly correlated with resting-state fMRI connectivity between the left caudate and the right fusiform gyrus, lateral occipital complex, and superior temporal gyrus. Given the basal ganglia's role in exploration, these findings suggest that tighter integration of the brain systems responsible for exploration and visuospatial processing may be critical for learning in a complex environment. PMID:25286145

  18. Sodium MRI: Methods and applications

    PubMed Central

    Madelin, Guillaume; Lee, Jae-Seung; Regatte, Ravinder R.; Jerschow, Alexej

    2014-01-01

    Sodium NMR spectroscopy and MRI have become popular in recent years through the increased availability of high-field MRI scanners, advanced scanner hardware and improved methodology. Sodium MRI is being evaluated for stroke and tumor detection, for breast cancer studies, and for the assessment of osteoarthritis and muscle and kidney functions, to name just a few. In this article, we aim to present an up-to-date review of the theoretical background, the methodology, the challenges and limitations, and current and potential new applications of sodium MRI. PMID:24815363

  19. Effect of the static magnetic field of the MR-scanner on ERPs: evaluation of visual, cognitive and motor potentials.

    PubMed

    Assecondi, S; Vanderperren, K; Novitskiy, N; Ramautar, J R; Fias, W; Staelens, S; Stiers, P; Sunaert, S; Van Huffel, S; Lemahieu, I

    2010-05-01

    This work investigates the influence of the static magnetic field of the MR-scanner on ERPs extracted from simultaneous EEG-fMRI recordings. The quality of the ERPs after BallistoCardioGraphic (BCG) artifact removal, as well as the reproducibility of the waveforms in different environments is investigated. We consider a Detection, a Go-Nogo and a Motor task, eliciting peaks that differ in amplitude, latency and scalp topography, repeated in two situations: outside the scanner room (0T) and inside the MR-scanner but without gradients (3T). The BCG artifact is removed by means of three techniques: the Average Artifact Subtraction (AAS) method, the Optimal Basis Set (OBS) method and the Canonical Correlation Analysis (CCA) approach. The performance of the three methods depends on the amount of averaged trials. Moreover, differences are found on both amplitude and latency of ERP components recorded in two environments (0T vs 3T). We showed that, while ERPs can be extracted from simultaneous EEG-fMRI data at 3T, the static magnetic field might affect the physiological processes under investigation. The reproducibility of the ERPs in different recording environments (0T vs 3T) is a relevant issue that deserves further investigation to clarify the equivalence of cognitive processes in both behavioral and imaging studies. Copyright 2010 International Federation of Clinical Neurophysiology. Published by Elsevier Ireland Ltd. All rights reserved.

  20. (Don't) panic in the scanner! How panic patients with agoraphobia experience a functional magnetic resonance imaging session.

    PubMed

    Lueken, Ulrike; Muehlhan, Markus; Wittchen, Hans-Ulrich; Kellermann, Thilo; Reinhardt, Isabelle; Konrad, Carsten; Lang, Thomas; Wittmann, André; Ströhle, Andreas; Gerlach, Alexander L; Ewert, Adrianna; Kircher, Tilo

    2011-07-01

    Although functional magnetic resonance imaging (fMRI) has gained increasing importance in investigating neural substrates of anxiety disorders, less is known about the stress eliciting properties of the scanner environment itself. The aim of the study was to investigate feasibility, self-reported distress and anxiety management strategies during an fMRI experiment in a comprehensive sample of patients with panic disorder and agoraphobia (PD/AG). Within the national research network PANIC-NET, n=89 patients and n=90 controls participated in a multicenter fMRI study. Subjects completed a retrospective questionnaire on self-reported distress, including a habituation profile and exploratory questions about helpful strategies. Drop-out rates and fMRI quality parameters were employed as markers of study feasibility. Different anxiety measures were used to identify patients particularly vulnerable to increased scanner anxiety and impaired data quality. Three (3.5%) patients terminated the session prematurely. While drop-out rates were comparable for patients and controls, data quality was moderately impaired in patients. Distress was significantly elevated in patients compared to controls; claustrophobic anxiety was furthermore associated with pronounced distress and lower fMRI data quality in patients. Patients reported helpful strategies, including motivational factors and cognitive coping strategies. The feasibility of large-scale fMRI studies on PD/AG patients could be proved. Study designs should nevertheless acknowledge that the MRI setting may enhance stress reactions. Future studies are needed to investigate the relationship between self-reported distress and fMRI data in patient groups that are subject to neuroimaging research. Copyright © 2010 Elsevier B.V. All rights reserved.

  1. An operational multispectral scanner for bathymetric surveys - The ABS NORDA scanner

    NASA Technical Reports Server (NTRS)

    Haimbach, Stephen P.; Joy, Richard T.; Hickman, G. Daniel

    1987-01-01

    The Naval Ocean Research and Development Activity (NORDA) is developing the Airborne Bathymetric Survey (ABS) system, which will take shallow water depth soundings from a Navy P-3 aircraft. The system combines active and passive sensors to obtain optical measurements of water depth. The ABS NORDA Scanner is the systems passive multispectral scanner whose design goal is to provide 100 percent coverage of the seafloor, to depths of 20 m in average coastal waters. The ABS NORDA Scanner hardware and operational environment is discussed in detail. The optical model providing the basis for depth extraction is reviewed and the proposed data processing routine discussed.

  2. Enhanced contrast efficiency in MRI by PEGylated magnetoliposomes loaded with PEGylated SPION: effect of SPION coating and micro-environment.

    PubMed

    Carvalho, A; Martins, M B F; Corvo, M L; Feio, G

    2014-10-01

    Magnetic core coatings modify the efficiency of nanoparticles used as contrast agents for MRI. In studies of these phenomena, care should be given to take into account possible effects of the specific micro-environment where coated nanoparticles are embedded. In the present work, the longitudinal and transverse relaxivities of superparamagnetic iron oxide nanoparticles stabilized with short-chain polyethylene glycol molecules (PEGylated SPIONs) were measured in a 7T magnetic field. PEGylated SPIONs with two different diameters (5 and 10nm) were studied. Two different PEGylated magnetoliposomes having liposome bilayer membranes composed of egg-phosphatidylcholine, cholesterol and 1,2-distearoyl-sn-glycerol-3-phosphoethanolamine-N-[methoxy PEG-2000] were also studied for their relaxivities, after being loaded with the PEGylated SPION of 5 or 10nm. This type of liposomes is known to have long residence time in bloodstream that leads to an attractive option for therapeutic applications. The influence of the magnetic core coating on the efficiency of the nanosystem as a negative contrast agent for MRI was then compared to the cumulative effect of the coating plus the specific micro-environment components. As a result, it was found that the PEGylated magnetoliposomes present a 4-fold higher efficiency as negative contrast agents for MRI than the PEGylated SPION.

  3. Portable biochip scanner device

    DOEpatents

    Perov, Alexander; Sharonov, Alexei; Mirzabekov, Andrei D.

    2002-01-01

    A portable biochip scanner device used to detect and acquire fluorescence signal data from biological microchips (biochips) is provided. The portable biochip scanner device employs a laser for emitting an excitation beam. An optical fiber delivers the laser beam to a portable biochip scanner. A lens collimates the laser beam, the collimated laser beam is deflected by a dichroic mirror and focused by an objective lens onto a biochip. The fluorescence light from the biochip is collected and collimated by the objective lens. The fluorescence light is delivered to a photomultiplier tube (PMT) via an emission filter and a focusing lens. The focusing lens focuses the fluorescence light into a pinhole. A signal output of the PMT is processed and displayed.

  4. Biochip scanner device

    DOEpatents

    Perov, Alexander; Belgovskiy, Alexander I.; Mirzabekov, Andrei D.

    2001-01-01

    A biochip scanner device used to detect and acquire fluorescence signal data from biological microchips or biochips and method of use are provided. The biochip scanner device includes a laser for emitting a laser beam. A modulator, such as an optical chopper modulates the laser beam. A scanning head receives the modulated laser beam and a scanning mechanics coupled to the scanning head moves the scanning head relative to the biochip. An optical fiber delivers the modulated laser beam to the scanning head. The scanning head collects the fluorescence light from the biochip, launches it into the same optical fiber, which delivers the fluorescence into a photodetector, such as a photodiode. The biochip scanner device is used in a row scanning method to scan selected rows of the biochip with the laser beam size matching the size of the immobilization site.

  5. EEG/functional MRI in epilepsy: The Queen Square Experience.

    PubMed

    Hamandi, Khalid; Salek-Haddadi, Afraim; Fish, David R; Lemieux, Louis

    2004-01-01

    The recording of EEG during functional MRI scanning (EEG/fMRI) has opened up new dimensions in brain research. The simultaneous recording of EEG activity and its temparospatial haemodynamic correlates is a powerful tool in the non-invasive mapping of normal and pathological brain function. The technological constraints imposed by having a conductor (the EEG) within the magnetic environment of the MRI scanner have been sufficiently overcome for high quality EEG recording during MRI. The initial applications of EEG/fMRI were in the study of epileptiform discharges in epilepsy. This has been rapidly followed by studies of normal EEG rhythms and evoked response in healthy subjects. The ability to map brain areas involved in the generation of epileptiform discharges recorded on the surface EEG has been shown using EEG/fMRI in patients with epilepsy. This has potential clinical applications in providing additional localizing information in the pre-surgical workup of epilepsy patients and in gaining a greater understanding of the neurobiology of interictal epileptiform discharges and epileptic seizures. In this review we address the issues in recording EEG during fMRI and review the application of EEG/fMRI in the study of patients with epilepsy at our centre.

  6. Effect of magnetic field fluctuation on ultra-low field MRI measurements in the unshielded laboratory environment.

    PubMed

    Liu, Chao; Chang, Baolin; Qiu, Longqing; Dong, Hui; Qiu, Yang; Zhang, Yi; Krause, Hans-Joachim; Offenhäusser, Andreas; Xie, Xiaoming

    2015-08-01

    Magnetic field fluctuations in our unshielded urban laboratory can reach hundreds of nT in the noisy daytime and is only a few nT in the quiet midnight. The field fluctuation causes the Larmor frequency fL to drift randomly for several Hz during the unshielded ultra-low field (ULF) nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) measurements, thus seriously spoiling the averaging effect and causing imaging artifacts. By using an active compensation (AC) technique based on the spatial correlation of the low-frequency magnetic field fluctuation, the field fluctuation can be suppressed to tens of nT, which is a moderate situation between the noisy daytime and the quiet midnight. In this paper, the effect of the field fluctuation on ULF MRI measurements was investigated. The 1D and 2D MRI signals of a water phantom were measured using a second-order low-Tc superconducting quantum interference device (SQUID) in three fluctuation cases: severe fluctuation (noisy daytime), moderate fluctuation (daytime with AC) and minute fluctuation (quiet midnight) when different gradient fields were applied. When the active compensation is applied or when the frequency encoding gradient field Gx reaches a sufficiently strong value in our measurements, the image artifacts become invisible in all three fluctuation cases. Therefore it is feasible to perform ULF-MRI measurements in unshielded urban environment without imaging artifacts originating from magnetic fluctuations by using the active compensation technique and/or strong gradient fields. Copyright © 2015 Elsevier Inc. All rights reserved.

  7. High Spatiotemporal Resolution Prostate MRI

    DTIC Science & Technology

    2016-09-01

    8 reconstruction of scans made of phantoms or of human subjects originating from multiple MRI scanners across Mayo. We are pleased with the...red lines are for the unenhanced test scans of the 32-Channel Prostate DCE- MRI June 1, 2016 Page 10 volunteer. The green shaded region shows...1 AD AWARD NUMBER: W81XWH-15-1-0341 TITLE: High Spatiotemporal Resolution Prostate MRI PRINCIPAL INVESTIGATOR: Stephen J. Riederer CONTRACTING

  8. Liquid-explosives scanners stand trial in airports

    SciTech Connect

    Matthews, Jermey N. A.

    2010-07-15

    Air passengers may once more be allowed to pack beverages, lotions, and hair spray in their carry-on luggage, if imaging technologies to detect liquid explosives can prove their worth. Several competing systems, including multi-energy x-ray systems and a low-field magnetic resonance imaging (MRI) scanner, are undergoing field tests at some airports worldwide.

  9. Hybrid Dispersion Laser Scanner

    PubMed Central

    Goda, K.; Mahjoubfar, A.; Wang, C.; Fard, A.; Adam, J.; Gossett, D. R.; Ayazi, A.; Sollier, E.; Malik, O.; Chen, E.; Liu, Y.; Brown, R.; Sarkhosh, N.; Di Carlo, D.; Jalali, B.

    2012-01-01

    Laser scanning technology is one of the most integral parts of today's scientific research, manufacturing, defense, and biomedicine. In many applications, high-speed scanning capability is essential for scanning a large area in a short time and multi-dimensional sensing of moving objects and dynamical processes with fine temporal resolution. Unfortunately, conventional laser scanners are often too slow, resulting in limited precision and utility. Here we present a new type of laser scanner that offers ∼1,000 times higher scan rates than conventional state-of-the-art scanners. This method employs spatial dispersion of temporally stretched broadband optical pulses onto the target, enabling inertia-free laser scans at unprecedented scan rates of nearly 100 MHz at 800 nm. To show our scanner's broad utility, we use it to demonstrate unique and previously difficult-to-achieve capabilities in imaging, surface vibrometry, and flow cytometry at a record 2D raster scan rate of more than 100 kHz with 27,000 resolvable points. PMID:22685627

  10. Hybrid dispersion laser scanner.

    PubMed

    Goda, K; Mahjoubfar, A; Wang, C; Fard, A; Adam, J; Gossett, D R; Ayazi, A; Sollier, E; Malik, O; Chen, E; Liu, Y; Brown, R; Sarkhosh, N; Di Carlo, D; Jalali, B

    2012-01-01

    Laser scanning technology is one of the most integral parts of today's scientific research, manufacturing, defense, and biomedicine. In many applications, high-speed scanning capability is essential for scanning a large area in a short time and multi-dimensional sensing of moving objects and dynamical processes with fine temporal resolution. Unfortunately, conventional laser scanners are often too slow, resulting in limited precision and utility. Here we present a new type of laser scanner that offers ∼1,000 times higher scan rates than conventional state-of-the-art scanners. This method employs spatial dispersion of temporally stretched broadband optical pulses onto the target, enabling inertia-free laser scans at unprecedented scan rates of nearly 100 MHz at 800 nm. To show our scanner's broad utility, we use it to demonstrate unique and previously difficult-to-achieve capabilities in imaging, surface vibrometry, and flow cytometry at a record 2D raster scan rate of more than 100 kHz with 27,000 resolvable points.

  11. Optical fuel pin scanner

    DOEpatents

    Kirchner, Tommy L.; Powers, Hurshal G.

    1983-01-01

    An optical scanner for indicia arranged in a focal plane at a cylindrical outside surface by use of an optical system including a rotatable dove prism. The dove prism transmits a rotating image of an encircled cylindrical surface area to a stationary photodiode array.

  12. Sound level dependence of auditory evoked potentials: simultaneous EEG recording and low-noise fMRI.

    PubMed

    Thaerig, Stefanie; Behne, Nicole; Schadow, Jeanette; Lenz, Daniel; Scheich, Henning; Brechmann, André; Herrmann, Christoph S

    2008-03-01

    The simultaneous recording of EEG and fMRI offers the advantage of combining precise spatial information about neuronal processing obtained by fMRI data with the high temporal resolution of EEG data. One problem for the analysis of auditory processing, however, is the noisy environment during fMRI measurements, especially when EPI sequences are employed. While EEG studies outside an MRI scanner repeatedly demonstrated a clear sound level-dependent increase of N1 amplitude, this finding was less obvious in simultaneous recordings inside a scanner. Based on the assumption that this inconsistency might be due to the confounding effect of the rather loud EPI noise, we employed a low-noise fMRI protocol. This method was previously used to reveal level-dependent fMRI activation in auditory cortex areas. We combined this method with simultaneous EEG recordings to investigate the effect of different sound intensities on the auditory evoked potentials. Eight participants without hearing deficits took part in our experiment. Frequency modulated tones (FM) were presented monaurally with two sound intensities (60 and 80 dB HL). The task of the participants was to categorize the FM-direction (rising vs. falling). Our results inside the scanner replicate the sound level dependence of AEPs from previous EEG studies outside the scanner. The data analysis revealed a significant shortening of N1 latency and an increase in the N1-P2 peak-to-peak amplitude for the higher sound intensity. On a descriptive level, the 80 dB HL stimulation yielded more activated voxels in fMRI and stronger activations. This effect was pronounced over the right hemisphere. Our results suggest that low-noise sequences might be advantageous for the examination of auditory processing in simultaneous EEG and fMRI recordings.

  13. Scanner calibration revisited

    PubMed Central

    2010-01-01

    Background Calibration of a microarray scanner is critical for accurate interpretation of microarray results. Shi et al. (BMC Bioinformatics, 2005, 6, Art. No. S11 Suppl. 2.) reported usage of a Full Moon BioSystems slide for calibration. Inspired by the Shi et al. work, we have calibrated microarray scanners in our previous research. We were puzzled however, that most of the signal intensities from a biological sample fell below the sensitivity threshold level determined by the calibration slide. This conundrum led us to re-investigate the quality of calibration provided by the Full Moon BioSystems slide as well as the accuracy of the analysis performed by Shi et al. Methods Signal intensities were recorded on three different microarray scanners at various photomultiplier gain levels using the same calibration slide from Full Moon BioSystems. Data analysis was conducted on raw signal intensities without normalization or transformation of any kind. Weighted least-squares method was used to fit the data. Results We found that initial analysis performed by Shi et al. did not take into account autofluorescence of the Full Moon BioSystems slide, which led to a grossly distorted microarray scanner response. Our analysis revealed that a power-law function, which is explicitly accounting for the slide autofluorescence, perfectly described a relationship between signal intensities and fluorophore quantities. Conclusions Microarray scanners respond in a much less distorted fashion than was reported by Shi et al. Full Moon BioSystems calibration slides are inadequate for performing calibration. We recommend against using these slides. PMID:20594322

  14. Scanner calibration revisited.

    PubMed

    Pozhitkov, Alexander E

    2010-07-01

    Calibration of a microarray scanner is critical for accurate interpretation of microarray results. Shi et al. (BMC Bioinformatics, 2005, 6, Art. No. S11 Suppl. 2.) reported usage of a Full Moon BioSystems slide for calibration. Inspired by the Shi et al. work, we have calibrated microarray scanners in our previous research. We were puzzled however, that most of the signal intensities from a biological sample fell below the sensitivity threshold level determined by the calibration slide. This conundrum led us to re-investigate the quality of calibration provided by the Full Moon BioSystems slide as well as the accuracy of the analysis performed by Shi et al. Signal intensities were recorded on three different microarray scanners at various photomultiplier gain levels using the same calibration slide from Full Moon BioSystems. Data analysis was conducted on raw signal intensities without normalization or transformation of any kind. Weighted least-squares method was used to fit the data. We found that initial analysis performed by Shi et al. did not take into account autofluorescence of the Full Moon BioSystems slide, which led to a grossly distorted microarray scanner response. Our analysis revealed that a power-law function, which is explicitly accounting for the slide autofluorescence, perfectly described a relationship between signal intensities and fluorophore quantities. Microarray scanners respond in a much less distorted fashion than was reported by Shi et al. Full Moon BioSystems calibration slides are inadequate for performing calibration. We recommend against using these slides.

  15. A novel, general-purpose, MR-compatible, manually actuated robotic manipulation system for minimally invasive interventions under direct MRI guidance.

    PubMed

    Christoforou, Eftychios G; Seimenis, Ioannis; Andreou, Eleni; Eracleous, Eleni; Tsekos, Nikolaos V

    2014-03-01

    Performing minimally invasive interventions under direct MRI guidance offers significant advantages. Required accessibility to the patient inside the MRI scanner is fairly limited, and employment of robotic assistance has been proposed. The development of MR-compatible robotic systems entails engineering challenges related to geometric constraints and the magnetic nature of the scanning environment. A novel, general-purpose, MR-compatible robotic manipulation system has been developed for the performance of minimally invasive interventions inside a cylindrical scanner under direct MRI guidance. The system is endowed with five degrees of freedom (DOF), is characterized by a unique kinematics structure and is manually actuated. The prototype system was shown to exhibit the required MR-compatibility characteristics and a task-space positioning ability of approximately 5 mm. Needle targeting testing demonstrated a 93% success rate in acquiring a 5 mm spherical target. Phantom testing was performed inside a 3 T scanner and results are reported for an experimental study simulating MRI-guided, manipulator-assisted, MR arthrography. Robotic assistance provided by the developed manipulator may effectively facilitate the performance of various MRI-guided, minimally invasive interventions inside a cylindrical scanner. Copyright © 2013 John Wiley & Sons, Ltd.

  16. A prototype manipulator for magnetic resonance-guided interventions inside standard cylindrical magnetic resonance imaging scanners.

    PubMed

    Tsekos, Nikolaos V; Ozcan, Alpay; Christoforou, Eftychios

    2005-11-01

    The aim of this work is to develop a remotely controlled manipulator to perform minimally invasive diagnostic and therapeutic interventions in the abdominal and thoracic cavities, with real-time magnetic resonance imaging (MRI) guidance inside clinical cylindrical MR scanners. The manipulator is composed of a three degree of freedom Cartesian motion system, which resides outside the gantry of the scanner, and serves as the holder and global positioner of a three degree of freedom arm which extends inside the gantry of the scanner At its distal end, the arm's end-effector can carry an interventional tool such as a biopsy needle, which can be advanced to a desired depth by means of a seventh degree of freedom. These seven degrees of freedom, provided by the entire assembly, offer extended manipulability to the device and a wide envelope of operation to the user, who can select a trajectory suitable for the procedure. The device is constructed of nonmagnetic and nonconductive fiberglass, and carbon fiber composite materials, to minimize artifacts and distortion on the MR images as well as eliminate effects on its operation from the high magnetic field and the fast switching magnetic field gradients used in MR imaging. A user interface was developed for man-in-the-loop control of the device using real-time MR images. The user interface fuses all sensor signals (MR and manipulator information) in a visualization, planning, and control command environment. Path planning is performed with graphical tools for setting the trajectory of insertion of the interventional tool using multislice and/or three dimensional MR images which are refreshed in real time. The device control is performed with an embedded computer which runs real-time control software. The manipulator compatibility with the MR environment and image-guided operation was tested on a 1.5 T MR scanner.

  17. Studying the neural bases of prism adaptation using fMRI: A technical and design challenge.

    PubMed

    Bultitude, Janet H; Farnè, Alessandro; Salemme, Romeo; Ibarrola, Danielle; Urquizar, Christian; O'Shea, Jacinta; Luauté, Jacques

    2016-12-30

    Prism adaptation induces rapid recalibration of visuomotor coordination. The neural mechanisms of prism adaptation have come under scrutiny since the observations that the technique can alleviate hemispatial neglect following stroke, and can alter spatial cognition in healthy controls. Relative to non-imaging behavioral studies, fMRI investigations of prism adaptation face several challenges arising from the confined physical environment of the scanner and the supine position of the participants. Any researcher who wishes to administer prism adaptation in an fMRI environment must adjust their procedures enough to enable the experiment to be performed, but not so much that the behavioral task departs too much from true prism adaptation. Furthermore, the specific temporal dynamics of behavioral components of prism adaptation present additional challenges for measuring their neural correlates. We developed a system for measuring the key features of prism adaptation behavior within an fMRI environment. To validate our configuration, we present behavioral (pointing) and head movement data from 11 right-hemisphere lesioned patients and 17 older controls who underwent sham and real prism adaptation in an MRI scanner. Most participants could adapt to prismatic displacement with minimal head movements, and the procedure was well tolerated. We propose recommendations for fMRI studies of prism adaptation based on the design-specific constraints and our results.

  18. Investigation on Laser Scanners

    SciTech Connect

    Fuss, B.

    2004-09-30

    The study and purchase of a three-dimensional laser scanner for a number of diverse metrology tasks at SLAC will be covered. Specifications including range, accuracy, scan density, resolution, field of view and more are discussed and the results of field tests and demonstrations by four potential vendors is covered. This will include details on the scanning of accelerator components in a now defunct ring on site and how the instruments compare.

  19. High throughput optical scanner

    SciTech Connect

    Basiji, David A.; van den Engh, Gerrit J.

    2001-01-01

    A scanning apparatus is provided to obtain automated, rapid and sensitive scanning of substrate fluorescence, optical density or phosphorescence. The scanner uses a constant path length optical train, which enables the combination of a moving beam for high speed scanning with phase-sensitive detection for noise reduction, comprising a light source, a scanning mirror to receive light from the light source and sweep it across a steering mirror, a steering mirror to receive light from the scanning mirror and reflect it to the substrate, whereby it is swept across the substrate along a scan arc, and a photodetector to receive emitted or scattered light from the substrate, wherein the optical path length from the light source to the photodetector is substantially constant throughout the sweep across the substrate. The optical train can further include a waveguide or mirror to collect emitted or scattered light from the substrate and direct it to the photodetector. For phase-sensitive detection the light source is intensity modulated and the detector is connected to phase-sensitive detection electronics. A scanner using a substrate translator is also provided. For two dimensional imaging the substrate is translated in one dimension while the scanning mirror scans the beam in a second dimension. For a high throughput scanner, stacks of substrates are loaded onto a conveyor belt from a tray feeder.

  20. MRI-powered Actuators for Robotic Interventions

    PubMed Central

    Vartholomeos, Panagiotis; Qin, Lei; Dupont, Pierre E.

    2012-01-01

    This paper presents a novel actuation technology for robotically assisted MRI-guided interventional procedures. Compact and wireless, the actuators are both powered and controlled by the MRI scanner. The design concept and performance limits are described and derived analytically. Simulation and experiments in a clinical MR scanner are used to validate the analysis and to demonstrate the capability of the approach for needle biopsies. The concepts of actuator locking mechanisms and multi-axis control are also introduced. PMID:22287082

  1. 51. View of upper radar scanner switch in radar scanner ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    51. View of upper radar scanner switch in radar scanner building 105 from upper catwalk level showing emanating waveguides from upper switch (upper one-fourth of photograph) and emanating waveguides from lower radar scanner switch in vertical runs. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  2. Heart MRI

    MedlinePlus

    Magnetic resonance imaging - cardiac; Magnetic resonance imaging - heart; Nuclear magnetic resonance - cardiac; NMR - cardiac; MRI of the heart; Cardiomyopathy - MRI; Heart failure - MRI; Congenital heart disease - MRI

  3. Integrated display scanner

    DOEpatents

    Veligdan, James T.

    2004-12-21

    A display scanner includes an optical panel having a plurality of stacked optical waveguides. The waveguides define an inlet face at one end and a screen at an opposite end, with each waveguide having a core laminated between cladding. A projector projects a scan beam of light into the panel inlet face for transmission from the screen as a scan line to scan a barcode. A light sensor at the inlet face detects a return beam reflected from the barcode into the screen. A decoder decodes the return beam detected by the sensor for reading the barcode. In an exemplary embodiment, the optical panel also displays a visual image thereon.

  4. Contrast-enhanced dynamic MRI protocol with improved spatial and time resolution for in vivo microimaging of the mouse with a 1.5-T body scanner and a superconducting surface coil.

    PubMed

    Ginefri, Jean-Christophe; Poirier-Quinot, Marie; Robert, Philippe; Darrasse, Luc

    2005-02-01

    Magnetic resonance imaging (MRI) is well suited for small animal model investigations to study various human pathologies. However, the assessment of microscopic information requires a high-spatial resolution (HSR) leading to a critical problem of signal-to-noise ratio limitations in standard whole-body imager. As contrast mechanisms are field dependent, working at high field do not allow to derive MRI criteria that may apply to clinical settings done in standard whole-body systems. In this work, a contrast-enhanced dynamic MRI protocol with improved spatial and time resolution was used to perform in vivo tumor model imaging on the mouse at 1.5 T. The needed sensitivity is provided by the use of a 12-mm superconducting surface coil operating at 77 K. High quality in vivo images were obtained and revealed well-defined internal structures of the tumor. A 3-D HSR sequence with voxels of 59x59x300 microm3 encoded within 6.9 min and a 2-D sequence with subsecond acquisition time and isotropic in-plane resolution of 234 microm were used to analyze the contrast enhancement kinetics in tumoral structures at long and short time scales. This work is a first step to better characterize and differentiate the dynamic behavior of tumoral heterogeneities.

  5. Advances in Clinical PET/MRI Instrumentation.

    PubMed

    Herzog, Hans; Lerche, Christoph

    2016-04-01

    In 2010, the first whole-body PET/MRI scanners installed for clinical use were the sequential Philips PET/MRI with PMT-based, TOF-capable technology and the integrated simultaneous Siemens PET/MRI. Avalanche photodiodes as non-magneto-sensitive readout electronics allowed PET integrated within the MRI. The experiences with these scanners showed that improvements of software aspects, such as attenuation correction, were necessary and that efficient protocols combining optimally PET and MRI must be still developed. In 2014, General Electric issued an integrated PET/MRI with SiPM-based PET detectors, allowing TOF-PET. Looking at the MRI components of current PET/MR imaging systems, primary improvements come from sequences and new coils.

  6. SERI laser scanner system

    SciTech Connect

    Matson, R.J.; Cannon, T.W.

    1980-10-01

    A Laser Scanner System (LSS) produces a photoresponse map and can be used for the nondestructive detection of nonuniformities in the photoresponse of a semiconductor device. At SERI the photoresponse maps are used to identify solar cell faults including microcracks, metallization breaks, regions of poor contact between metallization and the underlying emitter surface, and variations in emitter sheet resistance. The SERI LSS is patterned after the LSS unit documented in the NBS Special Publication 400-24 A Laser Scanner for Semiconductor Devices by D.E. Sawyer and D.W. Berning. Assuming reader familiarity with the above publication, the modifications introduced by SERI are specified with the intention that the two reports can be used to reproduce the SERI LSS. The optical and electronic systems are reviewed, briefly discussing the significant items of each. The most notable difference between the two systems is the SERI substitution of commercially available state-of-the-art modular electronics for the discreet component circuitry used in the NBS LSS.

  7. Brain Regions Involved in the Retrieval of Spatial and Episodic Details Associated with a Familiar Environment: An fMRI Study

    ERIC Educational Resources Information Center

    Hirshhorn, Marnie; Grady, Cheryl; Rosenbaum, R. Shayna; Winocur, Gordon; Moscovitch, Morris

    2012-01-01

    Functional magnetic resonance imaging (fMRI) was used to compare brain activity during the retrieval of coarse- and fine-grained spatial details and episodic details associated with a familiar environment. Long-time Toronto residents compared pairs of landmarks based on their absolute geographic locations (requiring either coarse or fine…

  8. Brain Regions Involved in the Retrieval of Spatial and Episodic Details Associated with a Familiar Environment: An fMRI Study

    ERIC Educational Resources Information Center

    Hirshhorn, Marnie; Grady, Cheryl; Rosenbaum, R. Shayna; Winocur, Gordon; Moscovitch, Morris

    2012-01-01

    Functional magnetic resonance imaging (fMRI) was used to compare brain activity during the retrieval of coarse- and fine-grained spatial details and episodic details associated with a familiar environment. Long-time Toronto residents compared pairs of landmarks based on their absolute geographic locations (requiring either coarse or fine…

  9. Nuclear magnetic resonance scanners

    SciTech Connect

    Danby, G.T.; Hsieh, H.C.H.; Jackson, J.W.; Damadian, R.V.

    1988-08-23

    This patent describes a medical NMR scanner comprising a primary field magnet assembly including: (a) a ferromagnetic frame defining a patient-receiving space adapted to receive a human body, the frame having a pair of opposed polar regions aligned on a polar axis and disposed on opposite sides of the patient-receiving space, and the frame including a substantially continuous ferro-magnetic flux return path extending between the polar regions remote from the patient-receiving space; (b) flux-generating means including superconductive windings and cryostat means for maintaining the windings at superconducting temperatures; and (c) support means for maintaining the windings in proximity to the frame so that when a current passes through the windings magnetic flux emanating from the windings produces a magnetic field within the patient-receiving space and at least a portion of the flux passes into the patient-receiving space by way of the polar regions.

  10. Laser Scanner Demonstration

    SciTech Connect

    Fuss, B.

    2005-09-06

    In the Summer of 2004 a request for proposals went out to potential vendors to offer a three-dimensional laser scanner for a number of unique metrology tasks at the Stanford Linear Accelerator Center (SLAC). Specifications were established including range, accuracy, scan density, resolution and field of view in consideration of anticipated department requirements. Four vendors visited the site to present their system and they were asked to perform three unique tests with their system on a two day visit to SLAC. Two of the three tests were created to emulate real-world applications at SLAC while the third was an accuracy and resolution series of experiments. The scope of these tests is presented and some of the vendor's results are included.

  11. A character string scanner

    NASA Technical Reports Server (NTRS)

    Enison, R. L.

    1971-01-01

    A computer program called Character String Scanner (CSS), is presented. It is designed to search a data set for any specified group of characters and then to flag this group. The output of the CSS program is a listing of the data set being searched with the specified group of characters being flagged by asterisks. Therefore, one may readily identify specific keywords, groups of keywords or specified lines of code internal to a computer program, in a program output, or in any other specific data set. Possible applications of this program include the automatic scan of an output data set for pertinent keyword data, the editing of a program to change the appearance of a certain word or group of words, and the conversion of a set of code to a different set of code.

  12. Dynamic Color Scanner System

    DTIC Science & Technology

    1974-05-01

    wm^^mrmm JlilJJLUJJ.l, UM *•* ". «^^~mw^-r mmmmmmmem DYNAMIC COLOR SCANNER SYSTEM L. T. Hunkler ITT Aerospaco/Gpticai Division S Fort Wayne ...Division, a division of International Telephone and Tele- graph Corporation, Fort Wayne , Indiana, under contract F33615-72- C-2071 for research and...iliKriiBiröfiiii-1, ■ ^ii ■"»*-—™""tWi "!—i^^^P«^ ^3 <o lil r^ ■ i u o o 0) (0 n •H Q (U ri 0) l-i 3 tP •H 20 SO-Z^H •— ■■■■I

  13. What Scanner products are available?

    Atmospheric Science Data Center

    2014-12-08

    ... and longwave estimate. ERBS covers all 24-hour local time, but only for regions between 60N and 60S. Scanner and Nonscanner ... algorithm. Because of these differences, it is best to work with these two data sets separately. ERBE/ERBS scanner operated ...

  14. Quantitative Tractography and Volumetric MRI in Blast and Blunt Force TBI: Predictors of Neurocognitive and Behavioral Outcome

    DTIC Science & Technology

    2013-10-01

    All participants underwent structural MRI and DTI on 3T General Electric MRI scanners housed within the UCSDFunctionalMagnetic Resonance Imaging (FMRI...Center on the UCSD La Jolla campus. Thirty-five par- ticipants (78%) were scanned with the scanner running the Excite HDx platform and, following the...FMRI Cen- ter’s scanner upgrade, data on 10 subjects were acquired with the scanner running the MR750 platform. Several studies support the

  15. Head MRI

    MedlinePlus

    ... the head; MRI - cranial; NMR - cranial; Cranial MRI; Brain MRI; MRI - brain; MRI - head ... the test, tell your provider if you have: Brain aneurysm clips An artificial heart valves Heart defibrillator ...

  16. Space-multiplexed optical scanner.

    PubMed

    Riza, Nabeel A; Yaqoob, Zahid

    2004-05-01

    A low-loss two-dimensional optical beam scanner that is capable of delivering large (e.g., > 10 degrees) angular scans along the elevation as well as the azimuthal direction is presented. The proposed scanner is based on a space-switched parallel-serial architecture that employs a coarse-scanner module and a fine-scanner module that produce an ultrahigh scan space-fill factor, e.g., 900 x 900 distinguishable beams in a 10 degrees (elevation) x 10 degrees (azimuth) scan space. The experimentally demonstrated one-dimensional version of the proposed scanner has a supercontinuous scan, 100 distinguishable beam spots in a 2.29 degrees total scan range, and 1.5-dB optical insertion loss.

  17. GRAPE: a graphical pipeline environment for image analysis in adaptive magnetic resonance imaging.

    PubMed

    Gabr, Refaat E; Tefera, Getaneh B; Allen, William J; Pednekar, Amol S; Narayana, Ponnada A

    2017-03-01

    We present a platform, GRAphical Pipeline Environment (GRAPE), to facilitate the development of patient-adaptive magnetic resonance imaging (MRI) protocols. GRAPE is an open-source project implemented in the Qt C++ framework to enable graphical creation, execution, and debugging of real-time image analysis algorithms integrated with the MRI scanner. The platform provides the tools and infrastructure to design new algorithms, and build and execute an array of image analysis routines, and provides a mechanism to include existing analysis libraries, all within a graphical environment. The application of GRAPE is demonstrated in multiple MRI applications, and the software is described in detail for both the user and the developer. GRAPE was successfully used to implement and execute three applications in MRI of the brain, performed on a 3.0-T MRI scanner: (i) a multi-parametric pipeline for segmenting the brain tissue and detecting lesions in multiple sclerosis (MS), (ii) patient-specific optimization of the 3D fluid-attenuated inversion recovery MRI scan parameters to enhance the contrast of brain lesions in MS, and (iii) an algebraic image method for combining two MR images for improved lesion contrast. GRAPE allows graphical development and execution of image analysis algorithms for inline, real-time, and adaptive MRI applications.

  18. Extraction of situational meaning by integrating multiple meanings in a complex environment: a functional MRI study.

    PubMed

    Sugiura, Motoaki; Wakusawa, Keisuke; Sekiguchi, Atsushi; Sassa, Yuko; Jeong, Hyeonjeong; Horie, Kaoru; Sato, Shigeru; Kawashima, Ryuta

    2009-08-01

    Humans extract behaviorally significant meaning from a situation by integrating meanings from multiple components of a complex daily environment. To determine the neural underpinnings of this ability, the authors performed functional magnetic resonance imaging of healthy subjects while the latter viewed naturalistic scenes of two people and an object, including a threatening situation of a person being attacked by an offender with an object. The authors used a two-factorial design: the object was either aversive or nonaversive, and the offender's action was either directed to the person or elsewhere. This allowed the authors to examine the neural response to object aversiveness and person-directed intention separately. A task unrelated to threat was also used to address incidental (i.e., subconscious or unintentional) detection. Assuming individual differences in incidental threat detection, the authors used a functional connectivity analysis using principal components analysis of intersubject variability. The left lateral orbitofrontal cortex and medial prefrontal cortex (MPFC) were specifically activated in response to a threatening situation. The threat-related component of intersubject variability was extracted from these data and showed a significant correlation with personality scores. There was also a correlation between threat-related intersubject variability and activation for object aversiveness in the left temporal pole and lateral orbitofrontal cortex; person-directed intention in the left superior frontal gyrus; threatening situations in the left MPFC; and independently for both factors in the right MPFC. Results demonstrate independent processing of object aversiveness and person-directed intention in the left temporal-orbitofrontal and superior frontal networks, respectively, and their integration into situational meaning in the MPFC.

  19. Side scanner for supermarkets: a new scanner design standard

    NASA Astrophysics Data System (ADS)

    Cheng, Charles K.; Cheng, J. K.

    1996-09-01

    High speed UPC bar code has become a standard mode of data capture for supermarkets in the US, Europe, and Japan. The influence of the ergonomics community on the design of the scanner is evident. During the past decade the ergonomic issues of cashier in check-outs has led to occupational hand-wrist cumulative trauma disorders, in most cases causing carpal tunnel syndrome, a permanent hand injury. In this paper, the design of a side scanner to resolve the issues is discussed. The complex optical module and the sensor for aforesaid side scanner is described. The ergonomic advantages offer the old counter mounted vertical scanner has been experimentally proved by the industrial funded study at an independent university.

  20. Intraoral 3D scanner

    NASA Astrophysics Data System (ADS)

    Kühmstedt, Peter; Bräuer-Burchardt, Christian; Munkelt, Christoph; Heinze, Matthias; Palme, Martin; Schmidt, Ingo; Hintersehr, Josef; Notni, Gunther

    2007-09-01

    Here a new set-up of a 3D-scanning system for CAD/CAM in dental industry is proposed. The system is designed for direct scanning of the dental preparations within the mouth. The measuring process is based on phase correlation technique in combination with fast fringe projection in a stereo arrangement. The novelty in the approach is characterized by the following features: A phase correlation between the phase values of the images of two cameras is used for the co-ordinate calculation. This works contrary to the usage of only phase values (phasogrammetry) or classical triangulation (phase values and camera image co-ordinate values) for the determination of the co-ordinates. The main advantage of the method is that the absolute value of the phase at each point does not directly determine the coordinate. Thus errors in the determination of the co-ordinates are prevented. Furthermore, using the epipolar geometry of the stereo-like arrangement the phase unwrapping problem of fringe analysis can be solved. The endoscope like measurement system contains one projection and two camera channels for illumination and observation of the object, respectively. The new system has a measurement field of nearly 25mm × 15mm. The user can measure two or three teeth at one time. So the system can by used for scanning of single tooth up to bridges preparations. In the paper the first realization of the intraoral scanner is described.

  1. Coastal Zone Color Scanner

    NASA Technical Reports Server (NTRS)

    Johnson, B.

    1988-01-01

    The Coastal Zone Color Scanner (CZCS) spacecraft ocean color instrument is capable of measuring and mapping global ocean surface chlorophyll concentration. It is a scanning radiometer with multiband capability. With new electronics and some mechanical, and optical re-work, it probably can be made flight worthy. Some additional components of a second flight model are also available. An engineering study and further tests are necessary to determine exactly what effort is required to properly prepare the instrument for spaceflight and the nature of interfaces to prospective spacecraft. The CZCS provides operational instrument capability for monitoring of ocean productivity and currents. It could be a simple, low cost alternative to developing new instruments for ocean color imaging. Researchers have determined that with global ocean color data they can: specify quantitatively the role of oceans in the global carbon cycle and other major biogeochemical cycles; determine the magnitude and variability of annual primary production by marine phytoplankton on a global scale; understand the fate of fluvial nutrients and their possible affect on carbon budgets; elucidate the coupling mechanism between upwelling and large scale patterns in ocean basins; answer questions concerning the large scale distribution and timing of spring blooms in the global ocean; acquire a better understanding of the processes associated with mixing along the edge of eddies, coastal currents, western boundary currents, etc., and acquire global data on marine optical properties.

  2. In-bore setup and Software for 3T MRI-guided Transperineal Prostate Biopsy

    PubMed Central

    Tokuda, Junichi; Tuncali, Kemal; Iordachita, Iulian; Song, Sang-Eun; Fedorov, Andriy; Oguro, Sota; Lasso, Andras; Fennessy, Fiona M; Tempany, Clare M; Hata, Nobuhiko

    2012-01-01

    MRI-guided prostate biopsy in conventional closed-bore scanners requires transferring the patient outside the bore during needle insertion due to the constrained in-bore space, causing a safety hazard and limiting image feedback. To address this issue, we present our custom-made in-bore setup and software to support MRI-guided transperineal prostate biopsy in a wide-bore 3 Tesla (T) MRI scanner. The setup consists of a specially designed tabletop and a needle-guiding template with Z-frame that give a physician access to the perineum of the patient at the imaging position and allow performance of MRI-guided transperineal biopsy without moving the patient out of the scanner. The software and Z-frame allow registration of the template, target planning, and biopsy guidance. Initially, we performed phantom experiments to assess the accuracy of template registration and needle placement in a controlled environment. Subsequently, we embarked on our clinical trial (N = 10). The phantom experiments showed that the translational errors of the template registration along the right-left (RP) and anterior-posterior (AP) axes were 1.1 ± 0.8 mm and 1.4 ± 1.1 mm respectively, while the rotational errors around the RL, AP, and superior-inferior axes were 0.8 ± 1.0 degrees, 1.7 ± 1.6 degrees, and 0.0 ± 0.0 degrees respectively. The 2D root-mean-square (RMS) needle placement error was 3.0 mm. The clinical biopsy procedures were safely carried out in all ten clinical cases with a needle placement error of 5.4 mm (2D RMS). In conclusion, transperineal prostate biopsy in a wide-bore 3T scanner is feasible using our custom-made tabletop set up and software, which supports manual needle placement without moving the patient out of the magnet. PMID:22951350

  3. In-bore setup and software for 3T MRI-guided transperineal prostate biopsy

    NASA Astrophysics Data System (ADS)

    Tokuda, Junichi; Tuncali, Kemal; Iordachita, Iulian; Song, Sang-Eun; Fedorov, Andriy; Oguro, Sota; Lasso, Andras; Fennessy, Fiona M.; Tempany, Clare M.; Hata, Nobuhiko

    2012-09-01

    MRI-guided prostate biopsy in conventional closed-bore scanners requires transferring the patient outside the bore during needle insertion due to the constrained in-bore space, causing a safety hazard and limiting image feedback. To address this issue, we present our custom-made in-bore setup and software to support MRI-guided transperineal prostate biopsy in a wide-bore 3 T MRI scanner. The setup consists of a specially designed tabletop and a needle-guiding template with a Z-frame that gives a physician access to the perineum of the patient at the imaging position and allows the physician to perform MRI-guided transperineal biopsy without moving the patient out of the scanner. The software and Z-frame allow registration of the template, target planning and biopsy guidance. Initially, we performed phantom experiments to assess the accuracy of template registration and needle placement in a controlled environment. Subsequently, we embarked on our clinical trial (N = 10). The phantom experiments showed that the translational errors of the template registration along the right-left (RP) and anterior-posterior (AP) axes were 1.1 ± 0.8 and 1.4 ± 1.1 mm, respectively, while the rotational errors around the RL, AP and superior-inferior axes were (0.8 ± 1.0)°, (1.7 ± 1.6)° and (0.0 ± 0.0)°, respectively. The 2D root-mean-square (RMS) needle-placement error was 3 mm. The clinical biopsy procedures were safely carried out in all ten clinical cases with a needle-placement error of 5.4 mm (2D RMS). In conclusion, transperineal prostate biopsy in a wide-bore 3T scanner is feasible using our custom-made tabletop setup and software, which supports manual needle placement without moving the patient out of the magnet.

  4. Design and Evaluation of a Cable-Driven fMRI-Compatible Haptic Interface to Investigate Precision Grip Control

    PubMed Central

    Vigaru, Bogdan; Sulzer, James; Gassert, Roger

    2016-01-01

    Our hands and fingers are involved in almost all activities of daily living and, as such, have a disproportionately large neural representation. Functional magnetic resonance imaging investigations into the neural control of the hand have revealed great advances, but the harsh MRI environment has proven to be a challenge to devices capable of delivering a large variety of stimuli necessary for well-controlled studies. This paper presents a fMRI-compatible haptic interface to investigate the neural mechanisms underlying precision grasp control. The interface, located at the scanner bore, is controlled remotely through a shielded electromagnetic actuation system positioned at the end of the scanner bed and then through a high stiffness, low inertia cable transmission. We present the system design, taking into account requirements defined by the biomechanics and dynamics of the human hand, as well as the fMRI environment. Performance evaluation revealed a structural stiffness of 3.3 N/mm, renderable forces up to 94 N, and a position control bandwidth of at least 19 Hz. MRI-compatibility tests showed no degradation in the operation of the haptic interface or the image quality. A preliminary fMRI experiment during a pilot study validated the usability of the haptic interface, illustrating the possibilities offered by this device. PMID:26441454

  5. Design and Evaluation of a Cable-Driven fMRI-Compatible Haptic Interface to Investigate Precision Grip Control.

    PubMed

    Vigaru, Bogdan; Sulzer, James; Gassert, Roger

    2015-10-01

    Our hands and fingers are involved in almost all activities of daily living and, as such, have a disproportionately large neural representation. Functional magnetic resonance imaging investigations into the neural control of the hand have revealed great advances, but the harsh MRI environment has proven to be a challenge to devices capable of delivering a large variety of stimuli necessary for well-controlled studies. This paper presents a fMRI-compatible haptic interface to investigate the neural mechanisms underlying precision grasp control. The interface, located at the scanner bore, is controlled remotely through a shielded electromagnetic actuation system positioned at the end of the scanner bed and then through a high stiffness, low inertia cable transmission. We present the system design, taking into account requirements defined by the biomechanics and dynamics of the human hand, as well as the fMRI environment. Performance evaluation revealed a structural stiffness of 3.3 N/mm, renderable forces up to 94 N, and a position control bandwidth of at least 19 Hz. MRI-compatibility tests showed no degradation in the operation of the haptic interface or the image quality. A preliminary fMRI experiment during a pilot study validated the usability of the haptic interface, illustrating the possibilities offered by this device.

  6. EU Directive 2004/40: field measurements of a 1.5 T clinical MR scanner.

    PubMed

    Riches, S F; Collins, D J; Scuffham, J W; Leach, M O

    2007-06-01

    The European Union (EU) Physical Agents (EMF) Directive [1] must be incorporated into UK law in 2008. The directive, which applies to employees working in MRI, sets legal exposure limits for two of the three types of EMF exposure employed in MRI; time-varying gradient fields and radiofrequency (RF) fields. Limits on the static field are currently not included but may be added at a later date. Conservative action values have been set for all three types of exposure including the static field. The absolute exposure limits will exclude staff from the scanner bore and adjacent areas during scanning, impacting on many clinical activities such as anaesthetic monitoring during sedated scans, paediatric scanning and interventional MRI. When the legislation comes into force, NHS Trusts, scanner companies and academic institutions will be required to show compliance with the law. We present results of initial measurements performed on a 1.5 T clinical MRI scanner. For the static field, the proposed action value is exceeded at 40 cm from the scanner bore and would be exceeded when positioning a patient for scanning. For the RF field, the action values were only exceeded within the bore at distances of 40 cm from the scanner ends during a very RF intensive sequence; MRI employees are unlikely to be in the bore during an acquisition. For the time-varying gradient fields the action values were exceeded 52 cm out from the mouth of the bore during two clinical sequences, and estimated current densities show the exposure limit to be exceeded at 40 cm for frequencies above 333 Hz. Limiting employees to distances greater than these from the scanner during acquisition will have a severe impact on the future use and development of MRI.

  7. Characterization of prostate cancer using T2 mapping at 3T: a multi-scanner study.

    PubMed

    Hoang Dinh, A; Souchon, R; Melodelima, C; Bratan, F; Mège-Lechevallier, F; Colombel, M; Rouvière, O

    2015-04-01

    To assess the prostate T2 value as a predictor of malignancy on two different 3T scanners. Eighty-three pre-prostatectomy multiparametric MRIs were retrospectively evaluated [67 obtained on a General Electric MRI (scanner 1) and 16 on a Philips MRI (scanner 2)]. After correlation with prostatectomy specimens, readers measured the T2 value of regions-of-interest categorized as "cancers", "false positive lesions", or "normal tissue". On scanner 1, in PZ, cancers had significantly lower T2 values than false positive lesions (P=0.02) and normal tissue (P=2×10(-9)). Gleason≥6 cancers had similar T2 values than false positive lesions and significantly higher T2 values than Gleason≥7 cancers (P=0.009). T2 values corresponding to a 25% and 75% risk of Gleason≥7 malignancy were respectively 132 ms (95% CI: 129-135 ms) and 77 ms (95% CI: 74-81 ms). In TZ, cancers had significantly lower T2 values than normal tissue (P=0.008), but not than false positive findings. Mean T2 values measured on scanner 2 were not significantly different than those measured on scanner 1 for all tissue classes. All tested tissue classes had similar mean T2 values on both scanners. In PZ, the T2 value was a significant predictor of Gleason≥7 cancers. Copyright © 2014 Éditions françaises de radiologie. Published by Elsevier Masson SAS. All rights reserved.

  8. MSS D Multispectral Scanner System

    NASA Technical Reports Server (NTRS)

    Lauletta, A. M.; Johnson, R. L.; Brinkman, K. L. (Principal Investigator)

    1982-01-01

    The development and acceptance testing of the 4-band Multispectral Scanners to be flown on LANDSAT D and LANDSAT D Earth resources satellites are summarized. Emphasis is placed on the acceptance test phase of the program. Test history and acceptance test algorithms are discussed. Trend data of all the key performance parameters are included and discussed separately for each of the two multispectral scanner instruments. Anomalies encountered and their resolutions are included.

  9. Multiple single-point imaging (mSPI) as a tool for capturing and characterizing MR signals and repetitive signal disturbances with high temporal resolution: the MRI scanner as a high-speed camera.

    PubMed

    Bakker, Chris J G; van Gorp, Jetse S; Verwoerd, Jan L; Westra, Albert H; Bouwman, Job G; Zijlstra, Frank; Seevinck, Peter R

    2013-09-01

    In this paper we aim to lay down and demonstrate the use of multiple single-point imaging (mSPI) as a tool for capturing and characterizing steady-state MR signals and repetitive disturbances thereof with high temporal resolution. To achieve this goal, various 2D mSPI sequences were derived from the nearest standard 3D imaging sequences by (i) replacing the excitation of a 3D slab by the excitation of a 2D slice orthogonal to the read axis, (ii) setting the readout gradient to zero, and (iii) leaving out the inverse Fourier transform in the read direction. The thus created mSPI sequences, albeit slow with regard to the spatial encoding part, were shown to result into a series of densely spaced 2D single-point images in the time domain enabling monitoring of the evolution of the magnetization with a high temporal resolution and without interference from any encoding gradients. The high-speed capabilities of mSPI were demonstrated by capturing and characterizing the free induction decays and spin echoes of substances with long T2s (>30 ms) and long and short T2*s (4 - >30 ms) and by monitoring the perturbation of the transverse magnetization by, respectively, a titanium cylinder, representing a static disturbance; a pulsed magnetic field gradient, representing a stimulus inherent to a conventional MRI experiment; and a pulsed electric current, representing an external stimulus. The results of the study indicate the potential of mSPI for assessing the evolution of the magnetization and, when properly synchronized with the acquisition, repeatable disturbances thereof with a temporal resolution that is ultimately limited by the bandwidth of the receiver, but in practice governed by the SNR of the experiment and the magnitude of the disturbance. Potential applications of mSPI can be envisaged in research areas that are concerned with MR signal behavior, MR system performance and MR evaluation of magnetically evoked responses.

  10. 3D ultrafast laser scanner

    NASA Astrophysics Data System (ADS)

    Mahjoubfar, A.; Goda, K.; Wang, C.; Fard, A.; Adam, J.; Gossett, D. R.; Ayazi, A.; Sollier, E.; Malik, O.; Chen, E.; Liu, Y.; Brown, R.; Sarkhosh, N.; Di Carlo, D.; Jalali, B.

    2013-03-01

    Laser scanners are essential for scientific research, manufacturing, defense, and medical practice. Unfortunately, often times the speed of conventional laser scanners (e.g., galvanometric mirrors and acousto-optic deflectors) falls short for many applications, resulting in motion blur and failure to capture fast transient information. Here, we present a novel type of laser scanner that offers roughly three orders of magnitude higher scan rates than conventional methods. Our laser scanner, which we refer to as the hybrid dispersion laser scanner, performs inertia-free laser scanning by dispersing a train of broadband pulses both temporally and spatially. More specifically, each broadband pulse is temporally processed by time stretch dispersive Fourier transform and further dispersed into space by one or more diffractive elements such as prisms and gratings. As a proof-of-principle demonstration, we perform 1D line scans at a record high scan rate of 91 MHz and 2D raster scans and 3D volumetric scans at an unprecedented scan rate of 105 kHz. The method holds promise for a broad range of scientific, industrial, and biomedical applications. To show the utility of our method, we demonstrate imaging, nanometer-resolved surface vibrometry, and high-precision flow cytometry with real-time throughput that conventional laser scanners cannot offer due to their low scan rates.

  11. Two-dimensional scanner apparatus

    NASA Astrophysics Data System (ADS)

    Kurtz, G. W.; Bankston, B. F.

    1984-03-01

    An X-Y scanner utilizes an eddy current or ultrasonic current test probe to detect surface defects in small flat plates and the like. The apparatus includes a scanner which travels on a pair of slide tubes in the X-direction. The scanner, carried on a carriage which slides in the Y-direction, is driven by a helix shaft with a closed-loop helix groove in which a follower pin carried by scanner rides. The carriage is moved incrementally in the Y-direction upon the completion of travel of the scanner back and forth in the X-direction by means of an indexing actuator and an indexing gear. The actuator is in the form of a ratchet which engages ratchet gear upon return of the scanner to the indexing position. The indexing gear is rotated a predetermined increment along a crack gear to move carriage incrementally in the Y-direction. Thus, simplified highly responsive mechanical motion may be had in a small lightweight portable unit for accurate scanning of small area.

  12. [Exposure to static magnetic field and health hazards during the operation of magnetic resonance scanners].

    PubMed

    Karpowicz, Jolanta; Gryz, Krzysztof; Politański, Piotr; Zmyślony, Marek

    2011-01-01

    Magnetic resonance imaging (MRI) scanners belong to the most modern imaging diagnostic devices, which involve workers' exposure to static magnetic fields (SMF) during the preparation and performance of MRI examinations. This paper presents the data on workers' exposure to SMF in the vicinity of MRI scanners and the analysis of SMF-related biological effects and health hazards to find out whether softening the legislative requirements concerning protection against SMF exposure of workers involved in MRI diagnostics is justified. Measurements in the vicinity of 1.5 T MRI magnets showed that exposure to SMF by various scanners depends on both SMF of magnets and scanners design, as well as on work organization. In a routine examination of one patient the radiographer is exposed to SMF exceeding 0.5 mT for app. 1.5-7 min, and up to 1.3 min to SMF exceeding 70 mT. In examinations of patients who need more attention, the duration of exposure may be significantly longer. The mean values (B mean) of exposure to SMF are 5.6-85 mT (mean 30 +/- 19 mT, N = 16). These data demonstrate that only well designed procedures, proper organization of workplace and awareness of workers how to attend the patients without being exposed to strong SMF allow for meeting the requirements of labor law concerning workers' exposure to SMF. The analysis of the available literature on biological effects of SMF has disclosed the lack of data on health effects of many years exposure of workers and the abundance of data demonstrating the biological activity of SMF. Therefore, a radical softening of legislative requirements concerning the exposure of workers' head or trunk is premature, and what is more, it is not indispensable for the development of MRI diagnostic. Such an action should be preceded by extensive international investigations on the health status of workers exposed to electromagnetic fields by MRI scanners.

  13. Novel magnetomechanical MR compatible vibrational device for producing kinesthetic illusion during fMRI

    PubMed Central

    Carr, Sarah J.; Borreggine, Kristin; Heilman, Jeremiah; Griswold, Mark; Walter, Benjamin L.

    2013-01-01

    Purpose: Functional MRI (fMRI) can provide insights into the functioning of the sensorimotor system, which is of particular interest in studying people with movement disorders or chronic pain conditions. This creates a demand for manipulanda that can fit and operate within the environment of a MRI scanner. Here, the authors present a magnetomechanical device that delivers a vibrotactile sensation to the skin with a force of approximately 9 N. Methods: MRI compatibility of the device was tested in a 3 T scanner using a phantom to simulate the head. Preliminary investigation into the effectiveness of the device at producing cortical and subcortical activity was also conducted with a group of seven healthy subjects. The vibration was applied to the right extensor carpi ulnaris tendon to induce a kinesthetic illusion of flexion and extension of the wrist. Results: The MRI compatibility tests showed the device did not produce image artifacts and the generated electromagnetic field did not disrupt the static magnetic field of the scanner or its operation. The subject group results showed activity in the contralateral putamen, premotor cortex, and dorsal lateral prefrontal cortex. Ipsilaterally, there was increased activity in the superior and inferior parietal lobules. Areas that activated bilaterally included the thalamus, anterior cingulate, secondary somatosensory areas (S2), temporal lobes, and visual association areas. Conclusions: This device offers an effective tool with precise control over the vibratory stimulus, delivering higher forces than some other types of devices (e.g., piezoelectric actuators). It can be useful for investigating sensory systems and sensorimotor integration. PMID:24320459

  14. Pulse Sequence Programming in a Dynamic Visual Environment: SequenceTree

    PubMed Central

    Magland, Jeremy F.; Li, Cheng; Langham, Michael C.; Wehrli, Felix W.

    2015-01-01

    Purpose To describe SequenceTree (ST), an open source. integrated software environment for implementing MRI pulse sequences, and ideally exported them to actual MRI scanners. The software is a user-friendly alternative to vendor-supplied pulse sequence design and editing tools and is suited for non-programmers and programmers alike. Methods The integrated user interface was programmed using the Qt4/C++ toolkit. As parameters and code are modified, the pulse sequence diagram is automatically updated within the user interface. Several aspects of pulse programming are handled automatically allowing users to focus on higher-level aspects of sequence design. Sequences can be simulated using a built-in Bloch equation solver and then exported for use on a Siemens MRI scanner. Ideally other types of scanners will be supported in the future. Results The software has been used for eight years in the authors’ laboratory and elsewhere and has been utilized in more than fifty peer-reviewed publications in areas such as cardiovascular imaging, solid state and non-proton NMR, MR elastography, and high resolution structural imaging. Conclusion ST is an innovative, open source, visual pulse sequence environment for MRI combining simplicity with flexibility and is ideal for both advanced users and those with limited programming experience. PMID:25754837

  15. Pulse sequence programming in a dynamic visual environment: SequenceTree.

    PubMed

    Magland, Jeremy F; Li, Cheng; Langham, Michael C; Wehrli, Felix W

    2016-01-01

    To describe SequenceTree, an open source, integrated software environment for implementing MRI pulse sequences and, ideally, exporting them to actual MRI scanners. The software is a user-friendly alternative to vendor-supplied pulse sequence design and editing tools and is suited for programmers and nonprogrammers alike. The integrated user interface was programmed using the Qt4/C++ toolkit. As parameters and code are modified, the pulse sequence diagram is automatically updated within the user interface. Several aspects of pulse programming are handled automatically, allowing users to focus on higher-level aspects of sequence design. Sequences can be simulated using a built-in Bloch equation solver and then exported for use on a Siemens MRI scanner. Ideally, other types of scanners will be supported in the future. SequenceTree has been used for 8 years in our laboratory and elsewhere and has contributed to more than 50 peer-reviewed publications in areas such as cardiovascular imaging, solid state and nonproton NMR, MR elastography, and high-resolution structural imaging. SequenceTree is an innovative, open source, visual pulse sequence environment for MRI combining simplicity with flexibility and is ideal both for advanced users and users with limited programming experience. © 2015 Wiley Periodicals, Inc.

  16. Scanner qualification with IntenCD based reticle error correction

    NASA Astrophysics Data System (ADS)

    Elblinger, Yair; Finders, Jo; Demarteau, Marcel; Wismans, Onno; Minnaert Janssen, Ingrid; Duray, Frank; Ben Yishai, Michael; Mangan, Shmoolik; Cohen, Yaron; Parizat, Ziv; Attal, Shay; Polonsky, Netanel; Englard, Ilan

    2010-03-01

    Scanner introduction into the fab production environment is a challenging task. An efficient evaluation of scanner performance matrices during factory acceptance test (FAT) and later on during site acceptance test (SAT) is crucial for minimizing the cycle time for pre and post production-start activities. If done effectively, the matrices of base line performance established during the SAT are used as a reference for scanner performance and fleet matching monitoring and maintenance in the fab environment. Key elements which can influence the cycle time of the SAT, FAT and maintenance cycles are the imaging, process and mask characterizations involved with those cycles. Discrete mask measurement techniques are currently in use to create across-mask CDU maps. By subtracting these maps from their final wafer measurement CDU map counterparts, it is possible to assess the real scanner induced printed errors within certain limitations. The current discrete measurement methods are time consuming and some techniques also overlook mask based effects other than line width variations, such as transmission and phase variations, all of which influence the final printed CD variability. Applied Materials Aera2TM mask inspection tool with IntenCDTM technology can scan the mask at high speed, offer full mask coverage and accurate assessment of all masks induced source of errors simultaneously, making it beneficial for scanner qualifications and performance monitoring. In this paper we report on a study that was done to improve a scanner introduction and qualification process using the IntenCD application to map the mask induced CD non uniformity. We will present the results of six scanners in production and discuss the benefits of the new method.

  17. Multispectral Scanner for Monitoring Plants

    NASA Technical Reports Server (NTRS)

    Gat, Nahum

    2004-01-01

    A multispectral scanner has been adapted to capture spectral images of living plants under various types of illumination for purposes of monitoring the health of, or monitoring the transfer of genes into, the plants. In a health-monitoring application, the plants are illuminated with full-spectrum visible and near infrared light and the scanner is used to acquire a reflected-light spectral signature known to be indicative of the health of the plants. In a gene-transfer- monitoring application, the plants are illuminated with blue or ultraviolet light and the scanner is used to capture fluorescence images from a green fluorescent protein (GFP) that is expressed as result of the gene transfer. The choice of wavelength of the illumination and the wavelength of the fluorescence to be monitored depends on the specific GFP.

  18. Choosing a Scanner: Points To Consider before Buying a Scanner.

    ERIC Educational Resources Information Center

    Raby, Chris

    1998-01-01

    Outlines ten factors to consider before buying a scanner: size of document; type of document; color; speed and volume; resolution; image enhancement; image compression; optical character recognition; scanning subsystem; and the option to use a commercial bureau service. The importance of careful analysis of requirements is emphasized. (AEF)

  19. Choosing a Scanner: Points To Consider before Buying a Scanner.

    ERIC Educational Resources Information Center

    Raby, Chris

    1998-01-01

    Outlines ten factors to consider before buying a scanner: size of document; type of document; color; speed and volume; resolution; image enhancement; image compression; optical character recognition; scanning subsystem; and the option to use a commercial bureau service. The importance of careful analysis of requirements is emphasized. (AEF)

  20. Design analysis of an MPI human functional brain scanner

    PubMed Central

    Mason, Erica E.; Cooley, Clarissa Z.; Cauley, Stephen F.; Griswold, Mark A.; Conolly, Steven M.; Wald, Lawrence L.

    2017-01-01

    MPI’s high sensitivity makes it a promising modality for imaging brain function. Functional contrast is proposed based on blood SPION concentration changes due to Cerebral Blood Volume (CBV) increases during activation, a mechanism utilized in fMRI studies. MPI offers the potential for a direct and more sensitive measure of SPION concentration, and thus CBV, than fMRI. As such, fMPI could surpass fMRI in sensitivity, enhancing the scientific and clinical value of functional imaging. As human-sized MPI systems have not been attempted, we assess the technical challenges of scaling MPI from rodent to human brain. We use a full-system MPI simulator to test arbitrary hardware designs and encoding practices, and we examine tradeoffs imposed by constraints that arise when scaling to human size as well as safety constraints (PNS and central nervous system stimulation) not considered in animal scanners, thereby estimating spatial resolutions and sensitivities achievable with current technology. Using a projection FFL MPI system, we examine coil hardware options and their implications for sensitivity and spatial resolution. We estimate that an fMPI brain scanner is feasible, although with reduced sensitivity (20×) and spatial resolution (5×) compared to existing rodent systems. Nonetheless, it retains sufficient sensitivity and spatial resolution to make it an attractive future instrument for studying the human brain; additional technical innovations can result in further improvements. PMID:28752130

  1. The hippocampus is involved in mental navigation for a recently learned, but not a highly familiar environment: a longitudinal fMRI study.

    PubMed

    Hirshhorn, Marnie; Grady, Cheryl; Rosenbaum, R Shayna; Winocur, Gordon; Moscovitch, Morris

    2012-04-01

    Functional magnetic resonance imaging (MRI) was used to investigate the hypothesis that memory for a large-scale environment is initially dependent on the hippocampus but is later supported by extra-hippocampal structures (e.g., precuneus, posterior parahippocampal cortex, and lingual gyrus) once the environment is well-learned. Participants were scanned during mental navigation tasks initially when they were newly arrived to the city of Toronto, and later after having lived and navigated within the city for 1 yr. In the first session, activation was observed in the right hippocampus, left precuneus, and postcentral gyrus. The second session revealed activation in the caudate and lateral temporal cortex, but not in the right hippocampus; additional activation was instead observed in the posterior parahippocampal cortex, lingual gyrus, and precuneus. These findings suggest that the right hippocampus is required for the acquisition of new spatial information but is not needed to represent this information when the environment is highly familiar.

  2. A case study in scanner optimisation.

    PubMed

    Dudley, N J; Gibson, N M

    2014-02-01

    Ultrasound scanner preset programmes are factory set or tailored to user requirements. Scanners may, therefore, have different settings for the same application, even on similar equipment in a single department. The aims of this study were: (1) to attempt to match the performance of two scanners, where one was preferred and (2) to assess differences between six scanners used for breast ultrasound within our organisation. The Nottingham Ultrasound Quality Assurance software was used to compare imaging performance. Images of a Gammex RMI 404GS test object were collected from six scanners, using default presets, factory presets and settings matched to a preferred scanner. Resolution, low contrast performance and high contrast performance were measured. The performance of two scanners was successfully matched, where one had been preferred. Default presets varied across the six scanners, three different presets being used. The most used preset differed in settings across the scanners, most notably in the use of different frequency modes. The factory preset was more consistent across the scanners, the main variation being in dynamic range (55-70 dB). Image comparisons showed significant differences, which were reduced or eliminated by adjustment of settings to match a reference scanner. It is possible to match scanner performance using the Nottingham Ultrasound Quality Assurance software as a verification tool. Ultrasound users should be aware that scanners may not behave in a similar fashion, even with apparently equivalent presets. It should be possible to harmonise presets by consensus amongst users.

  3. Scanner as a Fine Art

    ERIC Educational Resources Information Center

    Fontes, Kris

    2008-01-01

    Not every art department is fortunate enough to have access to digital cameras and image-editing software, but if a scanner, computer, and printer are available, students can create some imaginative and surreal work. This high-school level lesson begins with a discussion of self-portraits, and then moves to students creating images by scanning…

  4. Ultrasonic scanner for footprint identification

    NASA Technical Reports Server (NTRS)

    Derr, L. J.

    1974-01-01

    Scanner includes transducer, acoustical drive, acoustical receiver, X and Y position indicators, and cathode-ray tube. Transducer sends ultrasonic pulses into shoe sole or shoeprint. Reflected signals are picked up by acoustic receiver and fed to cathode-ray tube. Resulting display intensity is directly proportional to reflected signal magnitude.

  5. Scanner as a Fine Art

    ERIC Educational Resources Information Center

    Fontes, Kris

    2008-01-01

    Not every art department is fortunate enough to have access to digital cameras and image-editing software, but if a scanner, computer, and printer are available, students can create some imaginative and surreal work. This high-school level lesson begins with a discussion of self-portraits, and then moves to students creating images by scanning…

  6. MRI of the claustrophobic patient: interventionally configured magnets.

    PubMed

    Spouse, E; Gedroyc, W M

    2000-02-01

    The aim of this study was to determine whether or not claustrophobic patients would tolerate a scan in an open configuration interventional magnetic resonance (iMR) imaging unit, when they had failed to complete a diagnostic scan in a conventional MRI system. 50 claustrophobic subjects were entered into the study. Their response to the iMR environment was compared with their previous experience in an MRI scanner by means of a two-stage questionnaire. Part 1 was completed before their iMR scan and Part 2 following their attempt at imaging in the iMR unit. 60% (n = 30) of the participants were female and 40% (n = 20) were male, age range 25-71 years (mean 49.5 years). 48% (n = 24) were lumbar spine studies and 28% (n = 14) were studies of the head. 24% (n = 12) underwent scanning of other anatomical regions. 94% (n = 47) of participants underwent successful MRI in the interventional magnet without extra sedation. 6% (n = 3) failed to complete a diagnostic scan in the iMR machine. The GE Signa 0.5 T SP magnet allows successful MRI in 94% of the claustrophobic population who have failed to complete a scan in a conventional diagnostic machine.

  7. MRI Meets MPI: a bimodal MPI-MRI tomograph.

    PubMed

    Vogel, Patrick; Lother, Steffen; Rückert, Martin A; Kullmann, Walter H; Jakob, Peter M; Fidler, Florian; Behr, Volker C

    2014-10-01

    While magnetic particle imaging (MPI) constitutes a novel biomedical imaging technique for tracking superparamagnetic nanoparticles in vivo, unlike magnetic resonance imaging (MRI), it cannot provide anatomical background information. Until now these two modalities have been performed in separate scanners and image co-registration has been hampered by the need to reposition the sample in both systems as similarly as possible. This paper presents a bimodal MPI-MRI-tomograph that combines both modalities in a single system.MPI and MRI images can thus be acquired without moving the sample or replacing any parts in the setup. The images acquired with the presented setup show excellent agreement between the localization of the nanoparticles in MPI and the MRI background data. A combination of two highly complementary imaging modalities has been achieved.

  8. Improvements to Existing Jefferson Lab Wire Scanners

    SciTech Connect

    McCaughan, Michael D.; Tiefenback, Michael G.; Turner, Dennis L.

    2013-06-01

    This poster will detail the augmentation of selected existing CEBAF wire scanners with commercially available hardware, PMTs, and self created software in order to improve the scanners both in function and utility.

  9. A Magnetic Resonance Imaging-Conditional External Cardiac Defibrillator for Resuscitation Within the Magnetic Resonance Imaging Scanner Bore.

    PubMed

    Schmidt, Ehud J; Watkins, Ronald D; Zviman, Menekhem M; Guttman, Michael A; Wang, Wei; Halperin, Henry A

    2016-10-01

    Subjects undergoing cardiac arrest within a magnetic resonance imaging (MRI) scanner are currently removed from the bore and then from the MRI suite, before the delivery of cardiopulmonary resuscitation and defibrillation, potentially increasing the risk of mortality. This precludes many higher-risk (acute ischemic and acute stroke) patients from undergoing MRI and MRI-guided intervention. An MRI-conditional cardiac defibrillator should enable scanning with defibrillation pads attached and the generator ON, enabling application of defibrillation within the seconds of MRI after a cardiac event. An MRI-conditional external defibrillator may improve patient acceptance for MRI procedures. A commercial external defibrillator was rendered 1.5 Tesla MRI-conditional by the addition of novel radiofrequency filters between the generator and commercial disposable surface pads. The radiofrequency filters reduced emission into the MRI scanner and prevented cable/surface pad heating during imaging, while preserving all the defibrillator monitoring and delivery functions. Human volunteers were imaged using high specific absorption rate sequences to validate MRI image quality and lack of heating. Swine were electrically fibrillated (n=4) and thereafter defibrillated both outside and inside the MRI bore. MRI image quality was reduced by 0.8 or 1.6 dB, with the generator in monitoring mode and operating on battery or AC power, respectively. Commercial surface pads did not create artifacts deeper than 6 mm below the skin surface. Radiofrequency heating was within US Food and Drug Administration guidelines. Defibrillation was completely successful inside and outside the MRI bore. A prototype MRI-conditional defibrillation system successfully defibrillated in the MRI without degrading the image quality or increasing the time needed for defibrillation. It can increase patient acceptance for MRI procedures. © 2016 American Heart Association, Inc.

  10. An MRI-conditional motion phantom for the evaluation of high-intensity focused ultrasound protocols.

    PubMed

    Sagias, George; Yiallouras, Christos; Ioannides, Kleanthis; Damianou, Christakis

    2016-09-01

    The respiratory motion of abdominal organs is a serious obstacle in high-intensity focused ultrasound (HIFU) treatment with magnetic resonance imaging (MRI) guidance. In this study, a two-dimensional (2D) MRI-conditional motion phantom device was developed in order to evaluate HIFU protocols in synchronized and non-synchronized ablation of moving targets. The 2D phantom device simulates the respiratory motion of moving organs in both the left-right and craniocaudal directions. The device consists of MR-conditional materials which have been produced by a three-dimensional (3D) printer. The MRI compatibility of the motion phantom was tested successfully in an MRI scanner. In vitro experiments were carried out to evaluate HIFU ablation protocols that are minimally affected by target motion. It was shown that only in synchronized mode does HIFU produce thermal lesions, as tested on a gel phantom mimicking the moving target. The MRI-conditional phantom device was shown to be functional for its purpose and can be used as an evaluation tool for testing HIFU protocols for moving targets in an MRI environment. Copyright © 2015 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

  11. An MRI-Compatible Robotic System With Hybrid Tracking for MRI-Guided Prostate Intervention

    PubMed Central

    Krieger, Axel; Iordachita, Iulian I.; Guion, Peter; Singh, Anurag K.; Kaushal, Aradhana; Ménard, Cynthia; Pinto, Peter A.; Camphausen, Kevin; Fichtinger, Gabor

    2012-01-01

    This paper reports the development, evaluation, and first clinical trials of the access to the prostate tissue (APT) II system—a scanner independent system for magnetic resonance imaging (MRI)-guided transrectal prostate interventions. The system utilizes novel manipulator mechanics employing a steerable needle channel and a novel six degree-of-freedom hybrid tracking method, comprising passive fiducial tracking for initial registration and subsequent incremental motion measurements. Targeting accuracy of the system in prostate phantom experiments and two clinical human-subject procedures is shown to compare favorably with existing systems using passive and active tracking methods. The portable design of the APT II system, using only standard MRI image sequences and minimal custom scanner interfacing, allows the system to be easily used on different MRI scanners. PMID:22009867

  12. A Simple X-Y Scanner.

    ERIC Educational Resources Information Center

    Halse, M. R.; Hudson, W. J.

    1986-01-01

    Describes an X-Y scanner used to create acoustic holograms. Scanner is computer controlled and can be adapted to digitize pictures. Scanner geometry is discussed. An appendix gives equipment details. The control program in ATOM BASIC and 6502 machine code is available from the authors. (JM)

  13. Oceanographic scanner system design study, volume 1

    NASA Technical Reports Server (NTRS)

    1971-01-01

    The design is reported of a dual mode multispectral scanner, capable of satisfying both overland and oceanographic requirements. A complete system description and performance summary of the scanner are given. In addition, subsystem and component descriptions and performance analyses are treated in individual sections. The design of the scanner, with minimum modifications, interfaces to the ERTS spacecraft and the ground data handling system.

  14. [MRI-based radiotherapy planning].

    PubMed

    Largent, A; Nunes, J-C; Lafond, C; Périchon, N; Castelli, J; Rolland, Y; Acosta, O; de Crevoisier, R

    2017-07-06

    MRI-based radiotherapy planning is a topical subject due to the introduction of a new generation of treatment machines combining a linear accelerator and a MRI. One of the issues for introducing MRI in this task is the lack of information to provide tissue density information required for dose calculation. To cope with this issue, two strategies may be distinguished from the literature. Either a synthetic CT scan is generated from the MRI to plan the dose, or a dose is generated from the MRI based on physical underpinnings. Within the first group, three approaches appear: bulk density mapping assign a homogeneous density to different volumes of interest manually defined on a patient MRI; machine learning-based approaches model local relationship between CT and MRI image intensities from multiple data, then applying the model to a new MRI; atlas-based approaches use a co-registered training data set (CT-MRI) which are registered to a new MRI to create a pseudo CT from spatial correspondences in a final fusion step. Within the second group, physics-based approaches aim at computing the dose directly from the hydrogen contained within the tissues, quantified by MRI. Excepting the physics approach, all these methods generate a synthetic CT called "pseudo CT", on which radiotherapy planning will be finally realized. This literature review shows that atlas- and machine learning-based approaches appear more accurate dosimetrically. Bulk density approaches are not appropriate for bone localization. The fastest methods are machine learning and the slowest are atlas-based approaches. The less automatized are bulk density assignation methods. The physical approaches appear very promising methods. Finally, the validation of these methods is crucial for a clinical practice, in particular in the perspective of adaptive radiotherapy delivered by a linear accelerator combined with an MRI scanner. Copyright © 2017. Published by Elsevier SAS.

  15. Residual magnetism in an MRI suite after field-rampdown: what are the issues and experiences?

    PubMed

    Sammet, Steffen; Koch, Regina Maria; Aguila, Francisco; Knopp, Michael Vinzenz

    2010-05-01

    To investigate residual magnetization at different locations in the MRI suite at several time points prior, during and after field-rampdown with the goal to determine if the MRI suites could be reused in a clinical environment after the field-rampdown of MR scanners of different field strengths. Residual magnetism was measured with two gaussmeters in the MRI suites of an 8 Tesla (T) and a 0.7T whole body magnet at several time points prior, during and after field-rampdown. Residual magnetism, in the MRI suite after controlled rampdown of an 8T superconducting magnet, was not significantly elevated compared with magnetic fields in the environment. Through 40 days, no significant changes in magnetism could be seen compared with initial measurements directly after rampdown, as both gaussmeters consistently measured. Similar findings were also observed after the quenched shutdown of a 0.7T system but a remanence was observed. A controlled rampdown of even an ultrahigh field MR system does not lead to retained magnetic contamination, while forced quenched rampdown of a mid-field system revealed temporary remanence. There is no need to degauss an MRI suite when an appropriate steel composition has been used in the iron shield. Copyright 2010 Wiley-Liss, Inc.

  16. Quantitative Tractography and Volumetric MRI in Blast and Blunt Force TBI: Predictors of Neurocognitive and Behavioral Outcome

    DTIC Science & Technology

    2012-10-01

    MRI scanners 23 housed within the UCSD Functional Magnetic Resonance Imaging (FMRI) Center on the UCSD La Jolla 24 campus. Thirty-seven...participants were scanned on with the scanner equipped with the Excite HDx 25 19 mTBI White Matter 8 platform and, following the FMRI Center’s scanner upgrade...data on 10 subjects were acquired with the 1 scanner running the MR750 platform. There were no significant differences in regional FA values 2

  17. [Innovation and Future Technologies for PET Scanners].

    PubMed

    Yamaya, Taiga

    2015-01-01

    Positron emission tomography (PET) plays important roles in cancer diagnosis, neuroimaging and molecular imaging research; but potential points remain for which big improvements could be made, including spatial resolution, sensitivity and manufacturing costs. Higher spatial resolution is essential to enable earlier diagnosis, and improved sensitivity results in reduced radiation exposure and shortened measurement time. Therefore, research on next generation PET technologies remains a hot topic worldwide. In this paper, innovation and future technologies for the next generation PET scanners, such as time-of-flight measurement and simultaneous PET/MRI measurement, are described. Among them, depth-of-interaction (DOI) measurement in the radiation sensor will be a key technology to get any significant improvement in sensitivity while maintaining high spatial resolution. DOI measurement also has a potential to expand PET application fields because it allows for more flexible detector arrangement. As an example, the world's first, open-type PET geometry "OpenPET", which is expected to lead to PET imaging during treatment, is under development. The DOI detector itself continues to evolve with the help of recently developed semiconductor photodetectors, often referred to as silicon photomultipliers.

  18. Design of a Novel MRI Compatible Manipulator for Image Guided Prostate Interventions

    PubMed Central

    Krieger, Axel; Susil, Robert C.; Ménard, Cynthia; Coleman, Jonathan A.; Fichtinger, Gabor; Atalar, Ergin

    2012-01-01

    This paper reports a novel remotely actuated manipulator for access to prostate tissue under magnetic resonance imaging guidance (APT-MRI) device, designed for use in a standard high-field MRI scanner. The device provides three-dimensional MRI guided needle placement with millimeter accuracy under physician control. Procedures enabled by this device include MRI guided needle biopsy, fiducial marker placements, and therapy delivery. Its compact size allows for use in both standard cylindrical and open configuration MRI scanners. Preliminary in vivo canine experiments and first clinical trials are reported. PMID:15709668

  19. Large-area aircraft scanner

    NASA Astrophysics Data System (ADS)

    Iddings, Frank A.

    A program to determine the feasibility of present state-of-the-art NDI technology to produce a large-area scanner and to identify commercial equipment available to construct the desired system is presented. Work performed to attain these objectives is described, along with suggested modifications to the existing commercial equipment in order to meet the design criteria as closely as possible. Techniques that show the most promise at present are: D-sight, shearography, and pulse IR thermography (PIRT). D-sight is argued to be inadequate alone, but may well help form a system in conjunction with another technique. Shearography requires additional development in the area of stress application along with interpretation and overall application. PIRT is argued to be satisfactory as a large-area scanner system, at least for thin composite and metal panels.

  20. Vacuum Attachment for XRF Scanner

    NASA Technical Reports Server (NTRS)

    Schramm, Harry F.; Kaiser, Bruce

    2005-01-01

    Vacuum apparatuses have been developed for increasing the range of elements that can be identified by use of x-ray fluorescent (XRF) scanners of the type mentioned in the two immediately preceding articles. As a consequence of the underlying physical principles, in the presence of air, such an XRF scanner is limited to analysis of chlorine and elements of greater atomic number. When the XRF scanner is operated in a vacuum, it extends the range of analysis to lower atomic numbers - even as far as aluminum and sodium. Hence, more elements will be available for use in XRF labeling of objects as discussed in the two preceding articles. The added benefits of the extended capabilities also have other uses for NASA. Detection of elements of low atomic number is of high interest to the aerospace community. High-strength aluminum alloys will be easily analyzed for composition. Silicon, a major contaminant in certain processes, will be detectable before the process is begun, possibly eliminating weld or adhesion problems. Exotic alloys will be evaluated for composition prior to being placed in service where lives depend on them. And in the less glamorous applications, such as bolts and fasteners, substandard products and counterfeit items will be evaluated at the receiving function and never allowed to enter the operation

  1. IR line scanner on UAV

    NASA Astrophysics Data System (ADS)

    Liu, Shi-chao; Qin, Jie-xin; Qi, Hong-xing; Xiao, Gong-hai

    2011-08-01

    This paper introduces the designing principle and method of the IR line scanner on UAV in three aspects of optical-mechanical system, electronics system and processing software. It makes the system achieve good results in practical application that there are many features in the system such as light weight, small size, low power assumption, wide field of view, high instantaneous field of view, high noise equivalent temperature difference, wirelessly controlled and so on. The entire system is designed as follows: Multi-element scanner is put into use for reducing the electrical noise bandwidth, and then improving SNR; Square split aperture scanner is put into use for solving the image ratation distortion, besides fit for large velocity to height ratio; DSP is put into use for non-uniformity correction and background nosie subtraction, and then improving the imagery quality; SD card is put into use as image data storage media instead of the hard disk; The image data is stored in SD card in FAT32 file system, easily playbacked by processing software on Windows and Linux operating system; wireless transceiver module is put into use for wirelessly controlled.

  2. Microfabrication of fiber optic scanners

    NASA Astrophysics Data System (ADS)

    Fauver, Mark; Crossman-Bosworth, Janet L.; Seibel, Eric J.

    2002-06-01

    A cantilevered optical fiber is micromachined to function as a miniature resonant opto-mechanical scanner. By driving the base of the cantilevered fiber at a resonance frequency using a piezoelectric actuator, the free end of the cantilever beam becomes a scanned light source. The fiber scanners are designed to achieve wide field-of-view (FOV) and high scan frequency. We employ a non-linearly tapered profile fiber to achieve scan amplitudes of 1 mm at scan frequencies above 20 KHz. Scan angles of over 120 degree(s) (full angle) have been achieved. Higher order modes are also employed for scanning applications that require compactness while maintaining large angular FOV. Etching techniques are used to create the non-linearly tapered sections in single mode optical fiber. Additionally, micro-lenses are fabricated on the tips of the etched fibers, with lens diameters as small as 15 microns. Such lenses are capable of reducing the divergence angle of the emitted light to 5 degree(s) (full angle), with greater reduction expected by employing novel lens shaping techniques. Microfabricated optical fiber scanners have display applications ranging from micro-optical displays to larger panoramic displays. Applications for micro-image acquisition include small barcode readers to medical endoscopes.

  3. Design and Application of a New Automated Fluidic Visceral Stimulation Device for Human fMRI Studies of Interoception

    PubMed Central

    Gassert, Roger; Wanek, Johann; Michels, Lars; Mehnert, Ulrich; Kollias, Spyros S.

    2016-01-01

    Mapping the brain centers that mediate the sensory-perceptual processing of visceral afferent signals arising from the body (i.e., interoception) is useful both for characterizing normal brain activity and for understanding clinical disorders related to abnormal processing of visceral sensation. Here, we report a novel closed-system, electrohydrostatically driven master–slave device that was designed and constructed for delivering controlled fluidic stimulations of visceral organs and inner cavities of the human body within the confines of a 3T magnetic resonance imaging (MRI) scanner. The design concept and performance of the device in the MRI environment are described. In addition, the device was applied during a functional MRI (fMRI) investigation of visceral stimulation related to detrusor distention in two representative subjects to verify its feasibility in humans. System evaluation tests demonstrate that the device is MR-compatible with negligible impact on imaging quality [static signal-to-noise ratio (SNR) loss <2.5% and temporal SNR loss <3.5%], and has an accuracy of 99.68% for flow rate and 99.27% for volume delivery. A precise synchronization of the stimulus delivery with fMRI slice acquisition was achieved by programming the proposed device to detect the 5 V transistor–transistor logic (TTL) trigger signals generated by the MRI scanner. The fMRI data analysis using the general linear model analysis with the standard hemodynamic response function showed increased activations in the network of brain regions that included the insula, anterior and mid-cingulate and lateral prefrontal cortices, and thalamus in response to increased distension pressure on viscera. The translation from manually operated devices to an MR-compatible and MR-synchronized device under automatic control represents a useful innovation for clinical neuroimaging studies of human interoception. PMID:27551646

  4. A multichannel, real-time MRI RF power monitor for independent SAR determination

    PubMed Central

    El-Sharkawy, AbdEl-Monem M.; Qian, Di; Bottomley, Paul A.; Edelstein, William A.

    2012-01-01

    Purpose: Accurate measurements of the RF power delivered during clinical MRI are essential for safety and regulatory compliance, avoiding inappropriate restrictions on clinical MRI sequences, and for testing the MRI safety of peripheral and interventional devices at known RF exposure levels. The goal is to make independent RF power measurements to test the accuracy of scanner-reported specific absorption rate (SAR) over the extraordinary range of operating conditions routinely encountered in MRI. Methods: A six channel, high dynamic range, real-time power profiling system was designed and built for monitoring power delivery during MRI up to 440 MHz. The system was calibrated and used in two 3 T scanners to measure power applied to human subjects during MRI scans. The results were compared with the scanner-reported SAR. Results: The new power measurement system has highly linear performance over a 90 dB dynamic range and a wide range of MRI duty cycles. It has about 0.1 dB insertion loss that does not interfere with scanner operation. The measurements of whole-body SAR in volunteers showed that scanner-reported SAR was significantly overestimated by up to about 2.2 fold. Conclusions: The new power monitor system can accurately and independently measure RF power deposition over the wide range of conditions routinely encountered during MRI. Scanner-reported SAR values are not appropriate for setting exposure limits during device or pulse sequence testing. PMID:22559603

  5. A multichannel, real-time MRI RF power monitor for independent SAR determination

    SciTech Connect

    El-Sharkawy, AbdEl-Monem M.; Qian Di; Bottomley, Paul A.; Edelstein, William A.

    2012-05-15

    Purpose: Accurate measurements of the RF power delivered during clinical MRI are essential for safety and regulatory compliance, avoiding inappropriate restrictions on clinical MRI sequences, and for testing the MRI safety of peripheral and interventional devices at known RF exposure levels. The goal is to make independent RF power measurements to test the accuracy of scanner-reported specific absorption rate (SAR) over the extraordinary range of operating conditions routinely encountered in MRI. Methods: A six channel, high dynamic range, real-time power profiling system was designed and built for monitoring power delivery during MRI up to 440 MHz. The system was calibrated and used in two 3 T scanners to measure power applied to human subjects during MRI scans. The results were compared with the scanner-reported SAR. Results: The new power measurement system has highly linear performance over a 90 dB dynamic range and a wide range of MRI duty cycles. It has about 0.1 dB insertion loss that does not interfere with scanner operation. The measurements of whole-body SAR in volunteers showed that scanner-reported SAR was significantly overestimated by up to about 2.2 fold. Conclusions: The new power monitor system can accurately and independently measure RF power deposition over the wide range of conditions routinely encountered during MRI. Scanner-reported SAR values are not appropriate for setting exposure limits during device or pulse sequence testing.

  6. Cornice Monitoring with a Terrestrial Laser Scanner

    NASA Astrophysics Data System (ADS)

    Prokop, Alexander; Hancock, Holt

    2017-04-01

    Cornice failure poses a threat to infrastructure and human life in central Svalbard, where cornice fall avalanches comprise a significant portion of all observed avalanche activity. Cornice accretion occurs seasonally on the plateau edges of the mountains that border Longyearbyen - Svalbard's primary settlement - where snow entrained over the long fetches of the plateau summits is deposited by the prevailing winds. Here, we present the preliminary results from our first season regularly monitoring these cornice systems with the Riegl VZ-6000 terrestrial laser scanner. We demonstrate the applicability of TLS data acquisition for monitoring cornice system dynamics and discuss the utility of such measurements for hazard management purposes. Finally, we show how this unique high spatial resolution data will act as a reference dataset for modeling exercises to improve the process understanding of cornice development and failure - in arctic environments and throughout the world.

  7. Robust Object Segmentation Using a Multi-Layer Laser Scanner

    PubMed Central

    Kim, Beomseong; Choi, Baehoon; Yoo, Minkyun; Kim, Hyunju; Kim, Euntai

    2014-01-01

    The major problem in an advanced driver assistance system (ADAS) is the proper use of sensor measurements and recognition of the surrounding environment. To this end, there are several types of sensors to consider, one of which is the laser scanner. In this paper, we propose a method to segment the measurement of the surrounding environment as obtained by a multi-layer laser scanner. In the segmentation, a full set of measurements is decomposed into several segments, each representing a single object. Sometimes a ghost is detected due to the ground or fog, and the ghost has to be eliminated to ensure the stability of the system. The proposed method is implemented on a real vehicle, and its performance is tested in a real-world environment. The experiments show that the proposed method demonstrates good performance in many real-life situations. PMID:25356645

  8. Robust object segmentation using a multi-layer laser scanner.

    PubMed

    Kim, Beomseong; Choi, Baehoon; Yoo, Minkyun; Kim, Hyunju; Kim, Euntai

    2014-10-29

    The major problem in an advanced driver assistance system (ADAS) is the proper use of sensor measurements and recognition of the surrounding environment. To this end, there are several types of sensors to consider, one of which is the laser scanner. In this paper, we propose a method to segment the measurement of the surrounding environment as obtained by a multi-layer laser scanner. In the segmentation, a full set of measurements is decomposed into several segments, each representing a single object. Sometimes a ghost is detected due to the ground or fog, and the ghost has to be eliminated to ensure the stability of the system. The proposed method is implemented on a real vehicle, and its performance is tested in a real-world environment. The experiments show that the proposed method demonstrates good performance in many real-life situations.

  9. Design, operation, and safety of single-room interventional MRI suites: practical experience from two centers.

    PubMed

    White, Mark J; Thornton, John S; Hawkes, David J; Hill, Derek L G; Kitchen, Neil; Mancini, Laura; McEvoy, Andrew W; Razavi, Reza; Wilson, Sally; Yousry, Tarek; Keevil, Stephen F

    2015-01-01

    The design and operation of a facility in which a magnetic resonance imaging (MRI) scanner is incorporated into a room used for surgical or endovascular cardiac interventions presents several challenges. MR safety must be maintained in the presence of a much wider variety of equipment than is found in a diagnostic unit, and of staff unfamiliar with the MRI environment, without compromising the safety and practicality of the interventional procedure. Both the MR-guided cardiac interventional unit at Kings College London and the intraoperative imaging suite at the National Hospital for Neurology and Neurosurgery are single-room interventional facilities incorporating 1.5 T cylindrical-bore MRI scanners. The two units employ similar strategies to maintain MR safety, both in original design and day-to-day operational workflows, and between them over a decade of incident-free practice has been accumulated. This article outlines these strategies, highlighting both similarities and differences between the units, as well as some lessons learned and resulting procedural changes made in both units since installation. © 2014 Wiley Periodicals, Inc.

  10. A survey on abnormal uterine bleeding among radiographers with frequent MRI exposure using intrauterine contraceptive devices.

    PubMed

    Huss, A; Schaap, K; Kromhout, H

    2017-04-25

    Based on a previous case report of menometrorrhagia (prolonged/excessive uterine bleeding, occurring at irregular and/or frequent intervals) in MRI workers with intrauterine devices (IUDs), it was evaluated whether this association could be confirmed. A survey was performed among 381 female radiographers registered with their national association. Logistic regression was used to analyze associations of abnormal uterine bleeding with the frequency of working with MRI scanners, presence near the scanner/in the scanner room during image acquisition, and with scanner strength or type. A total of 68 women reported using IUDs, and 72 reported abnormal uterine bleeding. Compared with unexposed women not using IUDs, the odds ratio in women with IUDs working with MRI scanners was 2.09 (95% confidence interval 0.83-3.66). Associations were stronger if women working with MRI reported being present during image acquisition (odds ratio 3.43, 95% CI 1.26-9.34). Associations with scanner strength or type were not consistent. Radiographers using IUDs who are occupationally exposed to stray fields from MRI scanners report abnormal uterine bleeding more often than their co-workers without an IUD, or nonexposed co-workers with an IUD. In particular, radiographers present inside the scanner room during image acquisition showed an increased risk. Magn Reson Med, 2017. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

  11. A combined PET/CT scanner for clinical oncology.

    PubMed

    Beyer, T; Townsend, D W; Brun, T; Kinahan, P E; Charron, M; Roddy, R; Jerin, J; Young, J; Byars, L; Nutt, R

    2000-08-01

    The availability of accurately aligned, whole-body anatomical (CT) and functional (PET) images could have a significant impact on diagnosing and staging malignant disease and on identifying and localizing metastases. Computer algorithms to align CT and PET images acquired on different scanners are generally successful for the brain, whereas image alignment in other regions of the body is more problematic. A combined PET/CT tomograph with the unique capability of acquiring accurately aligned functional and anatomical images for any part of the human body has been designed and built. The PET/CT scanner was developed as a combination of a Siemens Somatom AR.SP spiral CT and a partial-ring, rotating ECAT ART PET scanner. All components are mounted on a common rotational support within a single gantry. The PET and CT components can be operated either separately, or in combined mode. In combined mode, the CT images are used to correct the PET data for scatter and attenuation. Fully quantitative whole-body images are obtained for an axial extent of 100 cm in an imaging time of less than 1 h. When operated in PET mode alone, transmission scans are acquired with dual 137Cs sources. The scanner is fully operational and the combined device has been operated successfully in a clinical environment. Over 110 patients have been imaged, covering a range of different cancers, including lung, esophageal, head and neck, melanoma, lymphoma, pancreas, and renal cell. The aligned PET and CT images are used both for diagnosing and staging disease and for evaluating response to therapy. We report the first performance measurements from the scanner and present some illustrative clinical studies acquired in cancer patients. A combined PET and CT scanner is a practical and effective approach to acquiring co-registered anatomical and functional images in a single scanning session.

  12. Comparison of three-dimensional scanner systems for craniomaxillofacial imaging.

    PubMed

    Knoops, Paul G M; Beaumont, Caroline A A; Borghi, Alessandro; Rodriguez-Florez, Naiara; Breakey, Richard W F; Rodgers, William; Angullia, Freida; Jeelani, N U Owase; Schievano, Silvia; Dunaway, David J

    2017-04-01

    Two-dimensional photographs are the standard for assessing craniofacial surgery clinical outcomes despite lacking three-dimensional (3D) depth and shape. Therefore, 3D scanners have been gaining popularity in various fields of plastic and reconstructive surgery, including craniomaxillofacial surgery. Head shapes of eight adult volunteers were acquired using four 3D scanners: 1.5T Avanto MRI, Siemens; 3dMDface System, 3dMD Inc.; M4D Scan, Rodin4D; and Structure Sensor, Occipital Inc. Accuracy was evaluated as percentage of data within a range of 2 mm from the 3DMDface System reconstruction, by surface-to-surface root mean square (RMS) distances, and with facial distance maps. Precision was determined by RMS. Relative to the 3dMDface System, accuracy was the highest for M4D Scan (90% within 2 mm; RMS of 0.71 mm ± 0.28 mm), followed by Avanto MRI (86%; 1.11 mm ± 0.33 mm) and Structure Sensor (80%; 1.33 mm ± 0.46). M4D Scan and Structure Sensor precision were 0.50 ± 0.04 mm and 0.51 ± 0.03 mm, respectively. Clinical and technical requirements govern scanner choice; however, 3dMDface System and M4D Scan provide high-quality results. It is foreseeable that compact, handheld systems will become more popular in the near future.

  13. MRI findings in Hirayama disease.

    PubMed

    Raval, Monali; Kumari, Rima; Dung, Aldrin Anthony Dung; Guglani, Bhuvnesh; Gupta, Nitij; Gupta, Rohit

    2010-11-01

    The objective of the study was to study the magnetic resonance imaging (MRI) features of Hirayama disease on a 3 Tesla MRI scanner. Nine patients with clinically suspected Hirayama disease were evaluated with neutral position, flexion, contrast-enhanced MRI and fast imaging employing steady-state acquisition (FIESTA) sequences. The spectrum of MRI features was evaluated and correlated with the clinical and electromyography findings. MRI findings of localized lower cervical cord atrophy (C5-C7), abnormal curvature, asymmetric cord flattening, loss of attachment of the dorsal dural sac and subjacent laminae in the neutral position, anterior displacement of the dorsal dura on flexion and a prominent epidural space were revealed in all patients on conventional MRI as well as with the dynamic 3D-FIESTA sequence. Intramedullary hyperintensity was seen in four patients on conventional MRI and on the 3D-FIESTA sequence. Flow voids were seen in four patients on conventional MRI sequences and in all patients with the 3D-FIESTA sequence. Contrast enhancement of the epidural component was noted in all the five patients with thoracic extensions. The time taken for conventional and contrast-enhanced MRI was about 30-40 min, while that for the 3D-FIESTA sequence was 6 min. Neutral and flexion position MRI and the 3D-FIESTA sequence compliment each other in displaying the spectrum of findings in Hirayama disease. A flexion study should form an essential part of the screening protocol in patients with suspected Hirayama disease. Newer sequences such as the 3D-FIESTA may help in reducing imaging time and obviating the need for contrast.

  14. Coastal zone color scanner retrospective

    NASA Astrophysics Data System (ADS)

    Mitchell, B. Greg

    1994-04-01

    The following special section of the Journal of Geophysical Research is dedicated to a retrospective of scientific studies using the coastal zone color scanner (CZCS) instrument. The CZCS was launched in late 1978 aboard the Nimbus 7 satellite as a "proof-of-concept" instrument to demonstrate the feasibility of using satellite platforms to monitor the distribution of oceanic phytoplankton in the world's oceans. It provided data until the middle of 1986. Phytoplankton primary production contributes approximately one half of the global biospheric fixation of organic matter by photosynthesis, thereby forming the base of the oceanic food web and providing a major sink for atmospheric CO2.

  15. Coastal Zone Color Scanner studies

    NASA Technical Reports Server (NTRS)

    Elrod, J.

    1988-01-01

    Activities over the past year have included cooperative work with a summer faculty fellow using the Coastal Zone Color Scanner (CZCS) imagery to study the effects of gradients in trophic resources on coral reefs in the Caribbean. Other research included characterization of ocean radiances specific to an acid-waste plume. Other activities include involvement in the quality control of imagery produced in the processing of the global CZCS data set, the collection of various other data global sets, and the subsequent data comparison and analysis.

  16. Design of an fMRI-compatible optical touch stripe based on frustrated total internal reflection.

    PubMed

    Jarrahi, Behnaz; Wanek, Johann

    2014-01-01

    Previously we developed a low-cost, multi-configurable handheld response system, using a reflective-type intensity modulated fiber-optic sensor (FOS) to accurately gather participants' behavioral responses during functional magnetic resonance imaging (fMRI). Inspired by the popularity and omnipresence of the fingertip-based touch sensing user interface devices, in this paper we present the design of a prototype fMRI-compatible optical touch stripe (OTS) as an alternative configuration. The prototype device takes advantage of a proven frustrated total internal reflection (FTIR) technique. By using a custom-built wedge-shaped optically transparent acrylic prism as an optical waveguide, and a plano-concave lens to provide the required light beam profile, the position of a fingertip touching the surface of the wedge prism can be determined from the deflected light beams that become trapped within the prism by total internal reflection. To achieve maximum sensitivity, the optical design of the wedge prism and lens were optimized through a series of light beam simulations using WinLens 3D Basic software suite. Furthermore, OTS performance and MRI-compatibility were assessed on a 3.0 Tesla MRI scanner running echo planar imaging (EPI) sequences. The results show that the OTS can detect a touch signal at high spatial resolution (about 0.5 cm), and is well suited for use within the MRI environment with average time-variant signal-to-noise ratio (tSNR) loss < 3%.

  17. High-precision GAFCHROMIC EBT film-based absolute clinical dosimetry using a standard flatbed scanner without the use of a scanner non-uniformity correction.

    PubMed

    Chung, Heeteak; Lynch, Bart; Samant, Sanjiv

    2010-04-17

    To report a study of the use of GAFCHROMIC EBT radiochromic film (RCF) digitized with a commercially available flatbed document scanner for accurate and reliable all-purpose two-dimensional (2D) absolute dosimetry within a clinical environment. We used a simplified methodology that yields high-precision dosimetry measurements without significant postirradiation correction. The Epson Expression 1680 Professional scanner and the Epson Expression 10000XL scanner were used to digitize the films. Both scanners were retrofitted with light-diffusing glass to minimize the effects of Newton rings. Known doses were delivered to calibration films. Flat and wedge fields were irradiated with variable depth of solid water and 5 cm back scatter solid water. No particular scanner nonuniformity effect corrections or significant post-scan image processing were carried out. The profiles were compared with CC04 ionization chamber profiles. The depth dose distribution was measured at a source-to-surface distance (SSD) of 100 cm with a field size of 10 x 10 cm2. Additionally, 22 IMRT fields were measured and evaluated using gamma index analysis. The overall accuracy of RCF with respect to CC04 was found to be 2%-4%. The overall accuracy of RCF was determined using the absolute mean of difference for all flat and wedge field profiles. For clinical IMRT fields, both scanners showed an overall gamma index passing rate greater than 90%. This work demonstrated that EBT films, in conjunction with a commercially available flatbed scanner, can be used as an accurate and precise absolute dosimeter. Both scanners showed that no significant scanner nonuniformity correction is necessary for accurate absolute dosimetry using the EBT films for field sizes smaller than or equal to 15 x 15 cm2.

  18. Design and Fabrication of an MRI-Compatible, Autonomous Incubation System.

    PubMed

    Khalilzad-Sharghi, Vahid; Xu, Huihui

    2015-10-01

    Tissue engineers have long sought access to an autonomous, imaging-compatible tissue incubation system that, with minimum operator handling, can provide real-time visualization and quantification of cells, tissue constructs, and organs. This type of screening system, capable of operating noninvasively to validate tissue, can overcome current limitations like temperature shock, unsustainable cellular environments, sample contamination, and handling/stress. However, this type of system has been a major challenge, until now. Here, we describe the design, fabrication, and characterization of an innovative, autonomous incubation system that is compatible with a 9.4 T magnetic resonance imaging (MRI) scanner. Termed the e-incubator (patent pending; application number: 13/953,984), this microcontroller-based system is integrated into an MRI scanner and noninvasively screens cells and tissue cultures in an environment where temperature, pH, and media/gas handling are regulated. The 4-week study discussed herein details the continuous operation of the e-incubator for a tissue-engineered osteogenic construct, validated by LIVE/DEAD(®) cell assays and histology. The evolving MR quantitative parameters of the osteogenic construct were used as biomarkers for bone tissue engineering and to further validate the quality of the product noninvasively before harvesting. Importantly, the e-incubator reliably facilitates culturing cells and tissue constructs to create engineered tissues and/or investigate disease therapies.

  19. Claustrophobia in MRI: the role of cognitions.

    PubMed

    Thorpe, Susan; Salkovskis, Paul M; Dittner, Antonia

    2008-10-01

    This study aimed to investigate the role of cognitive and behavioural factors in the experience of claustrophobia in the context of magnetic resonance imaging (MRI) scanners. One hundred and thirty outpatients attending an MRI unit completed questionnaires before and after their scans. Specific measures of experience in the scanner included subjective anxiety, panic symptoms, strategies used to stay calm and negative cognitions (such as 'I will suffocate' and 'I am going to faint in here'). Other general measures used included anxiety, depression, health anxiety and fears of restriction and suffocation. The amount of anxiety experienced during the scan was related to the perceived amount of time spent having physical symptoms of panic. Cognitions reported concerned the following: suffocation, harm caused by the machine and lack of perceived control. The number of strategies patients used to cope in the machine was also a related factor. Neither position in the scanner, nor head coil use nor previous experience of being in the scanner was related to levels of anxiety. The cognitions identified here may be used to construct a measure to identify those unable to enter the scanner or those most likely to become claustrophobic whilst undergoing the procedure and to further inform future brief, effective interventions.

  20. A radiation-hardened star scanner for spacecraft guidance and control

    NASA Technical Reports Server (NTRS)

    Birnbaum, M. M.; Bunker, R. L.; Tavolacci, J. T.

    1981-01-01

    A star scanner for the Galileo Project is described. Because it must function in the intense Jupiter radiation field, which consists primarily of high-energy electrons and protons, this star scanner is designed with radiation-hardness as a prime objective. The optics and the multiplier phototube are specially designed to minimize fluorescence and Cerenkov effects, and the electronic components to minimize ionization and displacement damage. The star-scanner layout provides maximum shielding for the optics and phototube. Test results predict successful operation in the expected Jovian radiation environment.

  1. A qualitative report on the subjective experience of intravenous psilocybin administered in an FMRI environment.

    PubMed

    Turton, S; Nutt, D J; Carhart-Harris, R L

    2014-01-01

    This report documents the phenomenology of the subjective experiences of 15 healthy psychedelic experienced volunteers who were involved in a functional magnetic resonance imaging (fMRI) study that was designed to image the brain effects of intravenous psilocybin. The participants underwent a semi-structured interview exploring the effects of psilocybin in the MRI scanner. These interviews were analysed by Interpretative Phenomenological Analysis. The resultant data is ordered in a detailed matrix, and presented in this paper. Nine broad categories of phenomenology were identified in the phenomenological analysis of the experience; perceptual changes including visual, auditory and somatosensory distortions, cognitive changes, changes in mood, effects of memory, spiritual or mystical type experiences, aspects relating to the scanner and research environment, comparisons with other experiences, the intensity and onset of effects, and individual interpretation of the experience. This article documents the phenomenology of psilocybin when given in a novel manner (intravenous injection) and setting (an MRI scanner). The findings of the analysis are consistent with previous published work regarding the subjective effects of psilocybin. There is much scope for further research investigating the phenomena identified in this paper.

  2. Exploiting Indoor Mobile Laser Scanner Trajectories for Semantic Interpretation of Point Clouds

    NASA Astrophysics Data System (ADS)

    Nikoohemat, S.; Peter, M.; Oude Elberink, S.; Vosselman, G.

    2017-09-01

    The use of Indoor Mobile Laser Scanners (IMLS) for data collection in indoor environments has been increasing in the recent years. These systems, unlike Terrestrial Laser Scanners (TLS), collect data along a trajectory instead of at discrete scanner positions. In this research, we propose several methods to exploit the trajectories of IMLS systems for the interpretation of point clouds. By means of occlusion reasoning and use of trajectory as a set of scanner positions, we are capable of detecting openings in cluttered indoor environments. In order to provide information about both the partitioning of the space and the navigable space, we use the voxel concept for point clouds. Furthermore, to reconstruct walls, floor and ceiling we exploit the indoor topology and plane primitives. The results show that the trajectory is a valuable source of data for feature detection and understanding of indoor MLS point clouds.

  3. MatMRI and MatHIFU: Matlab{trade mark, serif} toolboxes for real-time monitoring and control of MR-HIFU

    NASA Astrophysics Data System (ADS)

    Sinclair, Tony; Mougenot, Charles; Kivinen, Jon; Pichardo, Samuel

    2012-11-01

    Background. Availability of open tools is a key feature to facilitate the development of pre-clinical research of Magnetic Resonance-guided High Intensity Focused Ultrasound (MR-HIFU). MatMRI is a toolbox that allows direct communication with a Philips{trade mark, serif} MRI scanner in a Matlab{trade mark, serif} environment, which is well-known in many laboratories. MatMRI performs real-time acquisition of magnitude and phase images that can be processed to estimate changes of temperature. Available functionality of MatMRI includes acquisition of individual slices and volumetric data. Analogously to MatMRI, MatHIFU is a toolbox for the control of the Philips Sonalleve MR-HIFU system. MatHIFU allows the execution of user-defined treatment protocols such as thermal ablation, hyperthermia or drug delivery. MatMRI and MatHIFU can be used independently or in combination. Methods. MatMRI was based on the official tool for MRI data-dumping made by Philips Healthcare. Multi-threading capabilities were added to maximize real-time processing performance. Basic use of MatMRI involves four basic steps: initiate communication, subscribe to MRI data, query for new images and unsubscribe. If required, MatMRI can also pause/resume the scanning and update on real-time the location and orientation of the images. MatHIFU performs the execution of sonication protocols and allows real-time monitoring. Basic use of MatHIFU requires also four steps: preparation of sonication protocol, initiate communication, execute sonication protocol and monitor the state of execution. Results. MatMRI was integrated into existing software used to control a table designed for animal experimentation (FUS Instruments, Canada). The integration in the existing software was seamless and delivered real-time estimation of changes of temperature in a mouse model. Using MatHIFU and MatMRI, a complete new interface to control the Sonalleve system was developed to perform in vivo experiments allowing adapted

  4. In vivo cellular imaging with microscopes enabled by MEMS scanners

    NASA Astrophysics Data System (ADS)

    Ra, Hyejun

    High-resolution optical imaging plays an important role in medical diagnosis and biomedical research. Confocal microscopy is a widely used imaging method for obtaining cellular and sub-cellular images of biological tissue in reflectance and fluorescence modes. Its characteristic optical sectioning capability also enables three-dimensional (3-D) image reconstruction. However, its use has mostly been limited to excised tissues due to the requirement of high numerical aperture (NA) lenses for cellular resolution. Microscope miniaturization can enable in vivo imaging to make possible early cancer diagnosis and biological studies in the innate environment. In this dissertation, microscope miniaturization for in vivo cellular imaging is presented. The dual-axes confocal (DAC) architecture overcomes limitations of the conventional single-axis confocal (SAC) architecture to allow for miniaturization with high resolution. A microelectromechanical systems (MEMS) scanner is the central imaging component that is key in miniaturization of the DAC architecture. The design, fabrication, and characterization of the two-dimensional (2-D) MEMS scanner are presented. The gimbaled MEMS scanner is fabricated on a double silicon-on-insulator (SOI) wafer and is actuated by self-aligned vertical electrostatic combdrives. The imaging performance of the MEMS scanner in a DAC configuration is shown in a breadboard microscope setup, where reflectance and fluorescence imaging is demonstrated. Then, the MEMS scanner is integrated into a miniature DAC microscope. The whole imaging system is integrated into a portable unit for research in small animal models of human biology and disease. In vivo 3-D imaging is demonstrated on mouse skin models showing gene transfer and siRNA silencing. The siRNA silencing process is sequentially imaged in one mouse over time.

  5. Detection of Brain Reorganization in Pediatric Multiple Sclerosis Using Functional MRI

    DTIC Science & Technology

    2015-10-01

    delayed due to backlog in MRI scanning of patients and volunteers at our institution—we are behind schedule in recruiting and collecting data in 10 of...the MRI scanners at our institution, and slower than expected recruitment of eligible POMS patients from the MS clinic. Recruitment and fMRI scanning ...Page | 2 AWARD NUMBER: W81XWH-13-1-0464 TITLE: Detection of Brain Reorganization in Pediatric Multiple Sclerosis Using Functional MRI

  6. Laser Scanner For Automatic Storage

    NASA Astrophysics Data System (ADS)

    Carvalho, Fernando D.; Correia, Bento A.; Rebordao, Jose M.; Rodrigues, F. Carvalho

    1989-01-01

    The automated magazines are beeing used at industry more and more. One of the problems related with the automation of a Store House is the identification of the products envolved. Already used for stock management, the Bar Codes allows an easy way to identify one product. Applied to automated magazines, the bar codes allows a great variety of items in a small code. In order to be used by the national producers of automated magazines, a devoted laser scanner has been develloped. The Prototype uses an He-Ne laser whose beam scans a field angle of 75 degrees at 16 Hz. The scene reflectivity is transduced by a photodiode into an electrical signal, which is then binarized. This digital signal is the input of the decodifying program. The machine is able to see barcodes and to decode the information. A parallel interface allows the comunication with the central unit, which is responsible for the management of automated magazine.

  7. X-ray microtomographic scanners

    SciTech Connect

    Syryamkin, V. I. Klestov, S. A.

    2015-11-17

    The article studies the operating procedures of an X-ray microtomographic scanner and the module of reconstruction and analysis 3D-image of a test sample in particular. An algorithm for 3D-image reconstruction based on image shadow projections and mathematical methods of the processing are described. Chapter 1 describes the basic principles of X-ray tomography and general procedures of the device developed. Chapters 2 and 3 are devoted to the problem of resources saving by the system during the X-ray tomography procedure, which is achieved by preprocessing of the initial shadow projections. Preprocessing includes background noise removing from the images, which reduces the amount of shadow projections in general and increases the efficiency of the group shadow projections compression. In conclusion, the main applications of X-ray tomography are presented.

  8. Non-Destructive Testing Scanner

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Bio-Imaging Research's technology that originated in an aerospace program has come full circle with a new aerospace adaptation called the Advanced Computed Tomography Inspection System, or ACTIS. The medical version of CT scans the human body for tumors or other abnormalities, the ACTIS system finds imperfections in aerospace structures and components, such as castings, assemblies, rocket motors and nozzles. ACTIS is described by its developer as the most versatile CT scanner available for non-destructive testing applications. ACTIS is a variable geometry system. ACTIS source and detectors can be moved closer together or farther apart to optimize the geometry for different sizes of test objects. The combination of variable geometry, three sources, and focusing detectors makes ACTIS cost effective for a broad range of applications. System can scan anything from very small turbine blades to large rocket assemblies.

  9. Spaceborne scanner imaging system errors

    NASA Technical Reports Server (NTRS)

    Prakash, A.

    1982-01-01

    The individual sensor system design elements which are the priori components in the registration and rectification process, and the potential impact of error budgets on multitemporal registration and side-lap registration are analyzed. The properties of scanner, MLA, and SAR imaging systems are reviewed. Each sensor displays internal distortion properties which to varying degrees make it difficult to generate on orthophoto projection of the data acceptable for multiple pass registration or meeting national map accuracy standards and is also affected to varying degrees by relief displacements in moderate to hilly terrain. Nonsensor related distortions, associated with the accuracy of ephemeris determination and platform stability, have a major impact on local geometric distortions. Platform stability improvements expected from the new multi mission spacecraft series and improved ephemeris and ground control point determination from the NAVSTAR/global positioning satellite systems are reviewed.

  10. Evaluation of a commercial flatbed document scanner and radiographic film scanner for radiochromic EBT film dosimetry.

    PubMed

    Matney, Jason E; Parker, Brent C; Neck, Daniel W; Henkelmann, Greg; Rosen, Isaac I

    2010-04-19

    The purpose of this study was to quantify the performance and assess the utility of two different types of scanners for radiochromic EBT film dosimetry: a commercial flatbed document scanner and a widely used radiographic film scanner. We evaluated the Epson Perfection V700 Photo flatbed scanner and the Vidar VXR Dosimetry Pro Advantage scanner as measurement devices for radiochromic EBT film. Measurements were made of scan orientation effects, response uniformity, and scanner noise. Scanners were tested using films irradiated with eight separate 3x3cm2 fields to doses ranging from 0.115-5.119 Gy. ImageJ and RIT software was used for analyzing the Epson and Vidar scans, respectively. For repeated scans of a single film, the measurements in each dose region were reproducible to within +/- 0.3% standard deviation (SD) with both scanners. Film-to-film variations for corresponding doses were measured to be within +/- 0.4% SD for both Epson scanner and Vidar scanners. Overall, the Epson scanner showed a 10% smaller range of pixel value compared to the Vidar scanner. Scanner noise was small: +/- 0.3% SD for the Epson and +/- 0.2% for the Vidar. Overall measurement uniformity for blank film in both systems was better than +/- 2%, provided that the leading and trailing 2 cm film edges were neglected in the Vidar system. In this region artifacts are attributed to the film rollers. Neither system demonstrated a clear measurement advantage. The Epson scanner is a relatively inexpensive method for analyzing radiochromic film, but there is a lack of commercially available software. For a clinic already using a Vidar scanner, applying it to radiochromic film is attractive because commercial software is available. However, care must be taken to avoid using the leading and trailing film edges.

  11. 21 CFR 892.1220 - Fluorescent scanner.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Fluorescent scanner. 892.1220 Section 892.1220 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1220 Fluorescent scanner. (a) Identification....

  12. 21 CFR 892.1220 - Fluorescent scanner.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Fluorescent scanner. 892.1220 Section 892.1220 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1220 Fluorescent scanner. (a) Identification....

  13. 21 CFR 892.1220 - Fluorescent scanner.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Fluorescent scanner. 892.1220 Section 892.1220 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1220 Fluorescent scanner. (a) Identification....

  14. 21 CFR 892.1220 - Fluorescent scanner.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Fluorescent scanner. 892.1220 Section 892.1220 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1220 Fluorescent scanner. (a) Identification....

  15. 21 CFR 892.1220 - Fluorescent scanner.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Fluorescent scanner. 892.1220 Section 892.1220 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1220 Fluorescent scanner. (a) Identification....

  16. Scanner Art and Links to Physics

    ERIC Educational Resources Information Center

    Russell, David

    2005-01-01

    A photocopier or scanner can be used to produce not only the standard motion graphs of physics, but a variety of other graphs that resemble gravitational and electrical fields. This article presents a starting point for exploring scanner graphics, which brings together investigation in art and design, physics, mathematics, and information…

  17. Academic and Career Advising of Scanners

    ERIC Educational Resources Information Center

    Bloom, Arvid J.; Tripp, Philip R.; Shaffer, Leigh S.

    2011-01-01

    "Scanners" has become a common term for a recently identified category of people who find choosing just one interest or career path difficult (Sher, 2006). Academic and career advisors who work with scanners will likely find that these students have difficulty selecting an academic major or career path and that they seem to suffer anxiety and a…

  18. Discriminant analyses of Bendix scanner data

    NASA Technical Reports Server (NTRS)

    Richardson, A. J.; Wiegand, C. L.; Leamer, R. W.; Gerbermann, A. H.; Torline, R. J.

    1972-01-01

    Flights over Weslaco, Texas are discussed, using the 9-channel Bendix scanner, providing calibrated data in the 380 to 1000 nm wavelength interval. These flights were at 2000 ft. These data gave seasonal coverage from the time signals, representing mainly the soil background. The ground truth data are provided; signature processing studies relating scanner data to ground truth were also carried out.

  19. fMRI-compatible rehabilitation hand device

    PubMed Central

    Khanicheh, Azadeh; Muto, Andrew; Triantafyllou, Christina; Weinberg, Brian; Astrakas, Loukas; Tzika, Aria; Mavroidis, Constantinos

    2006-01-01

    Background Functional magnetic resonance imaging (fMRI) has been widely used in studying human brain functions and neurorehabilitation. In order to develop complex and well-controlled fMRI paradigms, interfaces that can precisely control and measure output force and kinematics of the movements in human subjects are needed. Optimized state-of-the-art fMRI methods, combined with magnetic resonance (MR) compatible robotic devices for rehabilitation, can assist therapists to quantify, monitor, and improve physical rehabilitation. To achieve this goal, robotic or mechatronic devices with actuators and sensors need to be introduced into an MR environment. The common standard mechanical parts can not be used in MR environment and MR compatibility has been a tough hurdle for device developers. Methods This paper presents the design, fabrication and preliminary testing of a novel, one degree of freedom, MR compatible, computer controlled, variable resistance hand device that may be used in brain MR imaging during hand grip rehabilitation. We named the device MR_CHIROD (Magnetic Resonance Compatible Smart Hand Interfaced Rehabilitation Device). A novel feature of the device is the use of Electro-Rheological Fluids (ERFs) to achieve tunable and controllable resistive force generation. ERFs are fluids that experience dramatic changes in rheological properties, such as viscosity or yield stress, in the presence of an electric field. The device consists of four major subsystems: a) an ERF based resistive element; b) a gearbox; c) two handles and d) two sensors, one optical encoder and one force sensor, to measure the patient induced motion and force. The smart hand device is designed to resist up to 50% of the maximum level of gripping force of a human hand and be controlled in real time. Results Laboratory tests of the device indicate that it was able to meet its design objective to resist up to approximately 50% of the maximum handgrip force. The detailed compatibility tests

  20. "MRI Stealth" robot for prostate interventions.

    PubMed

    Stoianovici, Dan; Song, Danny; Petrisor, Doru; Ursu, Daniel; Mazilu, Dumitru; Muntener, Michael; Mutener, Michael; Schar, Michael; Patriciu, Alexandru

    2007-01-01

    The paper reports an important achievement in MRI instrumentation, a pneumatic, fully actuated robot located within the scanner alongside the patient and operating under remote control based on the images. Previous MRI robots commonly used piezoelectric actuation limiting their compatibility. Pneumatics is an ideal choice for MRI compatibility because it is decoupled from electromagnetism, but pneumatic actuators were hardly controllable. This achievement was possible due to a recent technology breakthrough, the invention of a new type of pneumatic motor, PneuStep 1, designed for the robot reported here with uncompromised MRI compatibility, high-precision, and medical safety. MrBot is one of the "MRI stealth" robots today (the second is described in this issue by Zangos et al.). Both of these systems are also multi-imager compatible, being able to operate with the imager of choice or cross-imaging modalities. For MRI compatibility the robot is exclusively constructed of nonmagnetic and dielectric materials such as plastics, ceramics, crystals, rubbers and is electricity free. Light-based encoding is used for feedback, so that all electric components are distally located outside the imager's room. MRI robots are modern, digital medical instruments in line with advanced imaging equipment and methods. These allow for accessing patients within closed bore scanners and performing interventions under direct (in scanner) imaging feedback. MRI robots could allow e.g. to biopsy small lesions imaged with cutting edge cancer imaging methods, or precisely deploy localized therapy at cancer foci. Our robot is the first to show the feasibility of fully automated in-scanner interventions. It is customized for the prostate and operates transperineally for needle interventions. It can accommodate various needle drivers for different percutaneous procedures such as biopsy, thermal ablations, or brachytherapy. The first needle driver is customized for fully automated low

  1. A novel front-end chip for a human PET scanner based on monolithic detector blocks

    NASA Astrophysics Data System (ADS)

    Sarasola, I.; Rato Mendes, P.; Cuerdo, R.; García de Acilu, P.; Navarrete, J.; Cela, J. M.; Oller, J. C.; Romero, L.; Pérez, J. M.

    2011-01-01

    We are developing a positron emission tomography (PET) scanner based on avalanche photodiodes (APD), monolithic LYSO:Ce scintillator crystals and a dedicated readout chip. All these components allow operation inside a magnetic resonance imaging (MRI) scanner with the aim of building a PET/MRI hybrid imaging system for clinical human brain studies. Previous work verified the functional performance of our first chip (VATA240) based on a leading edge comparator and the principle of operation of our radiation sensors, which are capable of providing reconstructed images of positron point sources with spatial resolutions of 2.1 mm FWHM. The new VATA241 chip presented in this work has been designed with the aim of reducing the coincidence window of our final PET scanner by implementing an on-chip constant fraction discriminator (CFD), as well as providing a better robustness for its implementation in the full-scale PET scanner. Results from the characterization of the VATA241 chip are presented, together with the first results on coincidence performance, validating the new design for our application.

  2. Electrodynamic headphones and woofers for application in magnetic resonance imaging scanners.

    PubMed

    Baumgart, F; Kaulisch, T; Tempelmann, C; Gaschler-Markefski, B; Tegeler, C; Schindler, F; Stiller, D; Scheich, H

    1998-10-01

    Electrodynamic speakers compatible with (functional) magnetic resonance imaging (MRI) are described. The speakers magnets are removed, their function is replaced by the scanner's magnetic field, resulting in an uncommon but efficient operation. The method can be used with headphones as well as woofers. Functional MRI is not associated with any known biological risks, but as a method for visualization of task-specific activation of brain regions it is undesirably noisy. Thus, it requires both noise protection and efficient sound transmission systems for delivering acoustic stimuli to subjects. Woofers could possibly be used in active noise-control systems. The speakers described in this paper can be used for either task.

  3. MRI Magnet for Human Brain

    NASA Astrophysics Data System (ADS)

    Urayama, Shin-Ichi

    Recent rapid demand increase and supply decrease for helium has raised the price in these years. Superconducting magnetic resonance imaging (MRI) magnets, which consume 20% of global production of helium as the cryogen, are therefore expected to be helium-free and high-temperature superconducting (HTS) materials are potent candidates to realize this. Because of the reason, we developed a cryogen-free 3T-MRI scanner for human brain research using Bi-2223 tapes. For scanning a subject in sitting position, a vertical bore was adopted. The magnet was designed for operating temperature of 20 K and for driven mode. Both target homogeneity and stability of the magnetic field in field of view (FOV) region were within 1 ppm. Not only the magnet but also the other important hard/softwares were produced by us. After the assembly, adjustments and imaging experiments with the scanner were carried out at 1.5 T successfully. Although ramp-up to 3 T succeeded three times, successive abnormal events happened for longer than ten minutes during the third ramp-down time, and finally the magnet got fatal damages. Here, we introduce the system and discuss on problems and potentials of HTS-MRI magnets.

  4. A quality improvement project to reduce hypothermia in infants undergoing MRI scanning.

    PubMed

    Dalal, Priti G; Porath, Janelle; Parekh, Uma; Dhar, Padmani; Wang, Ming; Hulse, Michael; Mujsce, Dennis; McQuillan, Patrick M

    2016-07-01

    Hypothermia prevention strategies during MRI scanning under general anesthesia in infants may pose a challenge due to the MRI scanner's technical constraints. Previous studies have demonstrated conflicting results related to increase or decrease in post-scan temperatures in children. We noted occurrences of post-scan hypothermia in anesthetized infants despite the use of routine passive warming techniques. The aims of our quality improvement project were (a) to identify variables associated with post-scan hypothermia in infants and (b) to develop and implement processes to reduce occurrence of hypothermia in neonatal intensive care unit (NICU) infants undergoing MRI. One hundred sixty-four infants undergoing MRI scanning were prospectively audited for post-scan body temperatures. A multidisciplinary team identified potential variables associated with post-scan hypothermia and designed preventative strategies: protocol development, risk factor identification, vigilance and use of a vacuum immobilizer. Another audit was performed, specifically focusing on NICU infants. In the initial phase, we found that younger age (P = 0.002), lower weight (P = 0.005), lower pre-scan temperature (P < 0.01), primary anesthetic technique with propofol (P < 0.01), advanced airway devices (P = 0.02) and being in the NICU (P < 0.01) were associated with higher odds for developing post-scan decrease in body temperature. Quality improvement processes decreased the occurrence of hypothermia in NICU infants undergoing MRI scanning from 65% to 18% (95% confidence interval for the difference, 26-70%, P < 0.001). Several variables, including being in the NICU, are associated with a decrease in post-scan temperature in infants undergoing MRI scanning under sedation/general anesthesia. Implementation of strategies to prevent hypothermia in infants may be challenging in the high-risk MRI environment. We were able to minimize this problem in clinical practice by

  5. The PRESTO technique for fMRI.

    PubMed

    van Gelderen, P; Duyn, J H; Ramsey, N F; Liu, G; Moonen, C T W

    2012-08-15

    In the early days of BOLD fMRI, the acquisition of T(2)(*) weighted data was greatly facilitated by rapid scan techniques such as EPI. The latter, however, was only available on a few MRI systems that were equipped with specialized hardware that allowed rapid switching of the imaging gradients. For this reason, soon after the invention of fMRI, the scan technique PRESTO was developed to make rapid T(2)(*) weighted scanning available on standard clinical scanners. This method combined echo shifting, which allows for echo times longer than the sequence repetition time, with acquisition of multiple k-space lines per excitation. These two concepts were combined in order to achieve a method fast enough for fMRI, while maintaining a sufficiently long echo time for optimal contrast. PRESTO has been primarily used for 3D scanning, which minimized the contribution of large vessels due to inflow effects. Although PRESTO is still being used today, its appeal has lessened somewhat due to increased gradient performance of modern MRI scanners. Compared to 2D EPI, PRESTO may have somewhat reduced temporal stability, which is a disadvantage for fMRI that may not outweigh the advantage of reduced inflow effects provided by 3D scanning. In this overview, the history of the development of the PRESTO is presented, followed by a qualitative comparison with EPI. Published by Elsevier Inc.

  6. Object 3D surface reconstruction approach using portable laser scanner

    NASA Astrophysics Data System (ADS)

    Xu, Ning; Zhang, Wei; Zhu, Liye; Li, Changqing; Wang, Shifeng

    2017-06-01

    The environment perception plays the key role for a robot system. The 3D surface of the objects can provide essential information for the robot to recognize objects. This paper present an approach to reconstruct objects' 3D surfaces using a portable laser scanner we designed which consists of a single-layer laser scanner, an encoder, a motor, power supply and mechanical components. The captured point cloud data is processed to remove the discrete points, denoise filtering, stitching and registration. Then the triangular mesh generation of point cloud is accomplished by using Gaussian bilateral filtering, ICP real-time registration and greedy triangle projection algorithm. The experiment result shows the feasibility of the device designed and the algorithm proposed.

  7. MRI in guiding and assessing intramyocardial therapy.

    PubMed

    Saeed, M; Saloner, D; Weber, O; Martin, A; Henk, C; Higgins, C

    2005-05-01

    Cardiovascular intervention, using MRI guidance, is challenging for clinical applications. Real-time imaging sequences with high spatial resolution are needed for monitoring intramyocardial delivery of drug, gene, or stem cell therapies. New generation MR scanners make local intramyocardial and vascular wall therapies feasible. Contrast-enhanced MRI is used for assessing myocardial ischemia, infarction, and scar tissue. Active (microcoils) and passive (T1 and T2* mechanisms) tracking methods have been used for visualization of endovascular catheters. Safety issues related to potential heating of endovascular devices is still a major obstacle for MRI-guided interventions. Fabrication of MRI-compatible interventional devices is limited. Noninvasive imaging strategies will be critical in defining spatial and temporal characteristics of angiogenesis and myocardial repair as well as in assessing the efficacy of new therapies in ischemic heart disease. MRI contrast media improve the capability of MRI by delineating the target and vascular tree. Labeling stem cells enables MRI to trace distribution, differentiation, and survival in myocardium and vascular wall. In the long term, MRI in guiding and assessing intramyocardial therapy may circumvent the limitations of peripherally administered cell therapy, X-ray angiography, and nuclear imaging. MRI represents a highly attractive discipline whose systematic development will foster the implementation of new cardiac and vascular therapies.

  8. 16. SITE BUILDING 002 SCANNER BUILDING FRONT LOBBY ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    16. SITE BUILDING 002 - SCANNER BUILDING - FRONT LOBBY VIEW. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  9. 17. SITE BUILDING 002 SCANNER BUILDING COMMANDER'S OFFICE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    17. SITE BUILDING 002 - SCANNER BUILDING - COMMANDER'S OFFICE VIEW. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  10. Eddy current X-Y scanner system

    NASA Technical Reports Server (NTRS)

    Kurtz, G. W.

    1983-01-01

    The Nondestructive Evaluation Branch of the Materials and Processes Laboratory became aware of a need for a miniature, portable X-Y scanner capable of performing eddy current or other nondestructive testing scanning operations such as ultrasonic, or small areas of flat plate. The technical description and operational theory of the X-Y scanner system designed and built to fulfill this need are covered. The scanner was given limited testing and performs according to its design intent, which is to scan flat plate areas of approximately 412 sq cm (64 sq in) during each complete cycle of scanning.

  11. Pulsed Doppler lidar airborne scanner

    NASA Technical Reports Server (NTRS)

    Dimarzio, C. A.; Mcvicker, D. B.; Morrow, C. E.; Negus, C. C.

    1985-01-01

    This report covers the work accomplished during the reporting period on Pulsed Doppler Lidar Airborne Scanner and describes plans for the next reporting period. The objectives during the current phase of the contract are divided into four phases. Phase 1 includes ground testing of the system and analysis of data from the 1981 Severe Storms Test Flights. Phase 2 consists of preflight preparation and planning for the 1983 flight series. The flight test itself will be performed during Phase 3, and Phase 4 consists of post-flight analysis and operation of the system after that flight test. The range profile from five samples taken during Flight 10, around 1700 Z is given. The lowest curve is taken from data collected upwind of Mt. Shasta at about 10,000 feet of altitude, in a clear atmosphere, where no signals were observed. It thus is a good representation of the noise level as a function of range. The next curve was taken downwind of the mountain, and shows evidence of atmospheric returns. There is some question as to whether the data are valid at all ranges, or some ranges are contaminated by the others.

  12. Miniaturized micro-optical scanners

    NASA Astrophysics Data System (ADS)

    Motamedi, M. Edward; Andrews, Angus P.; Gunning, William J.; Khoshnevisan, Moshen

    1994-11-01

    Optical beam scanners are critical components for airborne and space-based laser radar, on- machine-inspection systems, factory automation systems, and optical communication systems. We describe here a laser beam steering system based on dithering two complementary (positive and negative) microlens arrays. When the two microlens arrays are translated relative to one another in the plane parallel to their surfaces, the transmitted light beam is scanned in two directions. We have demonstrated scanning speeds up to 300 Hz with a pair of 6-mm- aperture microlens arrays designed for input from a HeNe laser. The output beam covers a discrete 16 X 16 spot scan pattern with about 3.6 mrad separation and only 400 (mu) rad of beam divergence, in close agreement with design predictions. This demo system is relatively compact; less than 2 in. on a side. We also describe several near-term applications, some critical design trade-offs, and important fabrication and design issues.

  13. MR-compatibility assessment of the first preclinical PET-MRI insert equipped with digital silicon photomultipliers

    NASA Astrophysics Data System (ADS)

    Wehner, J.; Weissler, B.; Dueppenbecker, P. M.; Gebhardt, P.; Goldschmidt, B.; Schug, D.; Kiessling, F.; Schulz, V.

    2015-03-01

    PET (positron emission tomography) with its high sensitivity in combination with MRI (magnetic resonance imaging) providing anatomic information with good soft-tissue contrast is considered to be a promising hybrid imaging modality. However, the integration of a PET detector into an MRI system is a challenging task since the MRI system is a sensitive device for external disturbances and provides a harsh environment for electronic devices. Consequently, the PET detector has to be transparent for the MRI system and insensitive to electromagnetic disturbances. Due to the variety of MRI protocols imposing a wide range of requirements regarding the MR-compatibility, an extensive study is mandatory to reliably assess worst-case interference phenomena between the PET detector and the MRI scanner. We have built the first preclinical PET insert, designed for a clinical 3 T MRI, using digital silicon photomultipliers (digital SiPM, type DPC 3200-22, Philips Digital Photon Counting). Since no thorough interference investigation with this new digital sensor has been reported so far, we present in this work such a comprehensive MR-compatibility study. Acceptable distortion of the B0 field homogeneity (volume RMS = 0.08 ppm, peak-to-peak value = 0.71 ppm) has been found for the PET detector installed. The signal-to-noise ratio degradation stays between 2-15% for activities up to 21 MBq. Ghosting artifacts were only found for demanding EPI (echo planar imaging) sequences with read-out gradients in Z direction caused by additional eddy currents originated from the PET detector. On the PET side, interference mainly between the gradient system and the PET detector occurred: extreme gradient tests were executed using synthetic sequences with triangular pulse shape and maximum slew rate. Under this condition, a relative degradation of the energy (⩽10%) and timing (⩽15%) resolution was noticed. However, barely measurable performance deterioration occurred when morphological MRI

  14. MR-compatibility assessment of the first preclinical PET-MRI insert equipped with digital silicon photomultipliers.

    PubMed

    Wehner, J; Weissler, B; Dueppenbecker, P M; Gebhardt, P; Goldschmidt, B; Schug, D; Kiessling, F; Schulz, V

    2015-03-21

    PET (positron emission tomography) with its high sensitivity in combination with MRI (magnetic resonance imaging) providing anatomic information with good soft-tissue contrast is considered to be a promising hybrid imaging modality. However, the integration of a PET detector into an MRI system is a challenging task since the MRI system is a sensitive device for external disturbances and provides a harsh environment for electronic devices. Consequently, the PET detector has to be transparent for the MRI system and insensitive to electromagnetic disturbances. Due to the variety of MRI protocols imposing a wide range of requirements regarding the MR-compatibility, an extensive study is mandatory to reliably assess worst-case interference phenomena between the PET detector and the MRI scanner. We have built the first preclinical PET insert, designed for a clinical 3 T MRI, using digital silicon photomultipliers (digital SiPM, type DPC 3200-22, Philips Digital Photon Counting). Since no thorough interference investigation with this new digital sensor has been reported so far, we present in this work such a comprehensive MR-compatibility study. Acceptable distortion of the B0 field homogeneity (volume RMS = 0.08 ppm, peak-to-peak value = 0.71 ppm) has been found for the PET detector installed. The signal-to-noise ratio degradation stays between 2-15% for activities up to 21 MBq. Ghosting artifacts were only found for demanding EPI (echo planar imaging) sequences with read-out gradients in Z direction caused by additional eddy currents originated from the PET detector. On the PET side, interference mainly between the gradient system and the PET detector occurred: extreme gradient tests were executed using synthetic sequences with triangular pulse shape and maximum slew rate. Under this condition, a relative degradation of the energy (⩽10%) and timing (⩽15%) resolution was noticed. However, barely measurable performance deterioration occurred when morphological MRI

  15. Imaging industry expectations for compressed sensing in MRI

    NASA Astrophysics Data System (ADS)

    King, Kevin F.; Kanwischer, Adriana; Peters, Rob

    2015-09-01

    Compressed sensing requires compressible data, incoherent acquisition and a nonlinear reconstruction algorithm to force creation of a compressible image consistent with the acquired data. MRI images are compressible using various transforms (commonly total variation or wavelets). Incoherent acquisition of MRI data by appropriate selection of pseudo-random or non-Cartesian locations in k-space is straightforward. Increasingly, commercial scanners are sold with enough computing power to enable iterative reconstruction in reasonable times. Therefore integration of compressed sensing into commercial MRI products and clinical practice is beginning. MRI frequently requires the tradeoff of spatial resolution, temporal resolution and volume of spatial coverage to obtain reasonable scan times. Compressed sensing improves scan efficiency and reduces the need for this tradeoff. Benefits to the user will include shorter scans, greater patient comfort, better image quality, more contrast types per patient slot, the enabling of previously impractical applications, and higher throughput. Challenges to vendors include deciding which applications to prioritize, guaranteeing diagnostic image quality, maintaining acceptable usability and workflow, and acquisition and reconstruction algorithm details. Application choice depends on which customer needs the vendor wants to address. The changing healthcare environment is putting cost and productivity pressure on healthcare providers. The improved scan efficiency of compressed sensing can help alleviate some of this pressure. Image quality is strongly influenced by image compressibility and acceleration factor, which must be appropriately limited. Usability and workflow concerns include reconstruction time and user interface friendliness and response. Reconstruction times are limited to about one minute for acceptable workflow. The user interface should be designed to optimize workflow and minimize additional customer training. Algorithm

  16. MRI Interscanner Agreement of the Association between the Susceptibility Vessel Sign and Histologic Composition of Thrombi.

    PubMed

    Bourcier, Romain; Détraz, Lili; Serfaty, Jean Michel; Delasalle, Beatrice Guyomarch; Mirza, Mahmood; Derraz, Imad; Toulgoat, Frédérique; Naggara, Olivier; Toquet, Claire; Desal, Hubert

    2017-08-03

    The susceptibility vessel sign (SVS) on magnetic resonance imaging (MRI) is related to thrombus location, composition, and size in acute stroke. No previous study has determined its inter-MRI scanner variability. We aimed to compare the diagnostic accuracy in-vitro of four different MRI scanners for the characterization of histologic thrombus composition. Thirty-five manufactured thrombi analogs of different composition that were histologically categorized as fibrin-dominant, mixed, or red blood cell (RBC)-dominant were scanned on four different MRI units with T2* sequence. Nine radiologists, blinded to thrombus composition and MRI scanner model, classified twice, in a 2-week interval, the SVS of each thrombus as absent, questionable, or present. We calculated the weighted kappa with 95% confidence interval (CI), sensitivity, specificity and accuracy of the SVS on each MRI scanner to detect RBC-dominant thrombi. The SVS was present in 42%, absent in 33%, and questionable in 25% of thrombi. The interscanner agreement was moderate to good, ranging from .45 (CI: .37-.52) to .67 (CI: .61-.74). The correlation between the SVS and the thrombus composition was moderate (κ: .50 [CI: .44-.55]) to good κ: .76 ([CI: .72-.80]). Sensitivity, specificity, and accuracy to identify RBC-dominant clots were significantly different between MRI scanners (P < .001). The diagnostic accuracy of SVS to determine thrombus composition varies significantly among MRI scanners. Normalization of T2*sequences between scanners may be needed to better predict thrombus composition in multicenter studies. Copyright © 2017 by the American Society of Neuroimaging.

  17. Development and testing of laser Doppler system components for wake vortex monitoring. Volume 2: Scanner operations manual

    NASA Technical Reports Server (NTRS)

    Edwards, B. B.; Coffey, E. W.

    1974-01-01

    The theory and operation of the scanner portion of the laser Doppler system for detecting and monitoring aircraft trailing vortices in an airport environment are discussed. Schematics, wiring diagrams, component values, and operation and checkout procedures are included.

  18. Information extraction techniques for multispectral scanner data

    NASA Technical Reports Server (NTRS)

    Malila, W. A.; Crane, R. B.; Turner, R. E.

    1972-01-01

    The applicability of recognition-processing procedures for multispectral scanner data from areas and conditions used for programming the recognition computers to other data from different areas viewed under different measurement conditions was studied. The reflective spectral region approximately 0.3 to 3.0 micrometers is considered. A potential application of such techniques is in conducting area surveys. Work in three general areas is reported: (1) Nature of sources of systematic variation in multispectral scanner radiation signals, (2) An investigation of various techniques for overcoming systematic variations in scanner data; (3) The use of decision rules based upon empirical distributions of scanner signals rather than upon the usually assumed multivariate normal (Gaussian) signal distributions.

  19. Hand-held optical fuel pin scanner

    DOEpatents

    Kirchner, T.L.; Powers, H.G.

    1980-12-07

    An optical scanner for indicia arranged in a focal plane perpendicular to an optical system including a rotatable dove prism. The dove prism transmits a rotating image to a stationary photodiode array.

  20. High voltage battery cell scanner development

    NASA Technical Reports Server (NTRS)

    Lepisto, J. W.; Decker, D. K.; Graves, J.

    1983-01-01

    Battery cell voltage scanners have been previously used in low voltage spacecraft applications. In connection with future missions involving an employment of high-power high voltage power subsystems and/or autonomous power subsystem management for unattended operation, it will be necessary to utilize battery cell voltage scanners to provide battery cell voltage information for early detection of impending battery cell degradation/failures. In preparation for such missions, a novel battery cell voltage scanner design has been developed. The novel design makes use of low voltage circuit modules which can be applied to high voltage batteries in a building block fashion. A description is presented of the design concept and test results of the high voltage battery cell scanner, and its operation with an autonomously managed power subsystem is discussed.

  1. Hand-held optical fuel pin scanner

    DOEpatents

    Kirchner, Tommy L.; Powers, Hurshal G.

    1987-01-01

    An optical scanner for indicia arranged in a focal plane perpendicular to an optical system including a rotatable dove prism. The dove prism transmits a rotating image to a stationary photodiode array.

  2. Advanced optical 3D scanners using DMD technology

    NASA Astrophysics Data System (ADS)

    Muenstermann, P.; Godding, R.; Hermstein, M.

    2017-02-01

    Optical 3D measurement techniques are state-of-the-art for highly precise, non-contact surface scanners - not only in industrial development, but also in near-production and even in-line configurations. The need for automated systems with very high accuracy and clear implementation of national precision standards is growing extremely due to expanding international quality guidelines, increasing production transparency and new concepts related to the demands of the fourth industrial revolution. The presentation gives an overview about the present technical concepts for optical 3D scanners and their benefit for customers and various different applications - not only in quality control, but also in design centers or in medical applications. The advantages of DMD-based systems will be discussed and compared to other approaches. Looking at today's 3D scanner market, there is a confusing amount of solutions varying from lowprice solutions to high end systems. Many of them are linked to a very special target group or to special applications. The article will clarify the differences of the approaches and will discuss some key features which are necessary to render optical measurement systems suitable for industrial environments. The paper will be completed by examples for DMDbased systems, e. g. RGB true-color systems with very high accuracy like the StereoScan neo of AICON 3D Systems. Typical applications and the benefits for customers using such systems are described.

  3. Measuring CT scanner variability of radiomics features

    PubMed Central

    Mackin, Dennis; Fave, Xenia; Zhang, Lifei; Fried, David; Yang, Jinzhong; Taylor, Brian; Rodriguez-Rivera, Edgardo; Dodge, Cristina; Jones, A. Kyle; Court, Laurence

    2015-01-01

    Objectives The purpose of this study was to determine the significance of inter-scanner variability in CT image radiomics studies. Materials and Methods We compared the radiomics features calculated for non-small cell lung cancer (NSCLC) tumors from 20 patients with those calculated for 17 scans of a specially designed radiomics phantom. The phantom comprised 10 cartridges, each filled with different materials to produce a wide range of radiomics feature values. The scans were acquired using General Electric, Philips, Siemens, and Toshiba scanners from four medical centers using their routine thoracic imaging protocol. The radiomics feature studied included the mean and standard deviations of the CT numbers as well as textures derived from the neighborhood gray-tone difference matrix. To quantify the significance of the inter-scanner variability, we introduced the metric feature noise. To look for patterns in the scans, we performed hierarchical clustering for each cartridge. Results The mean CT numbers for the 17 CT scans of the phantom cartridges spanned from -864 to 652 Hounsfield units compared with a span of -186 to 35 Hounsfield units for the CT scans of the NSCLC tumors, showing that the phantom’s dynamic range includes that of the tumors. The inter-scanner variability of the feature values depended on both the cartridge material and the feature, and the variability was large relative to the inter-patient variability in the NSCLC tumors for some features. The feature inter-scanner noise was greatest for busyness and least for texture strength. Hierarchical clustering produced different clusters of the phantom scans for each cartridge, although there was some consistent clustering by scanner manufacturer. Conclusions The variability in the values of radiomics features calculated on CT images from different CT scanners can be comparable to the variability in these features found in CT images of NSCLC tumors. These inter-scanner differences should be

  4. How flatbed scanners upset accurate film dosimetry.

    PubMed

    van Battum, L J; Huizenga, H; Verdaasdonk, R M; Heukelom, S

    2016-01-21

    Film is an excellent dosimeter for verification of dose distributions due to its high spatial resolution. Irradiated film can be digitized with low-cost, transmission, flatbed scanners. However, a disadvantage is their lateral scan effect (LSE): a scanner readout change over its lateral scan axis. Although anisotropic light scattering was presented as the origin of the LSE, this paper presents an alternative cause. Hereto, LSE for two flatbed scanners (Epson 1680 Expression Pro and Epson 10000XL), and Gafchromic film (EBT, EBT2, EBT3) was investigated, focused on three effects: cross talk, optical path length and polarization. Cross talk was examined using triangular sheets of various optical densities. The optical path length effect was studied using absorptive and reflective neutral density filters with well-defined optical characteristics (OD range 0.2-2.0). Linear polarizer sheets were used to investigate light polarization on the CCD signal in absence and presence of (un)irradiated Gafchromic film. Film dose values ranged between 0.2 to 9 Gy, i.e. an optical density range between 0.25 to 1.1. Measurements were performed in the scanner's transmission mode, with red-green-blue channels. LSE was found to depend on scanner construction and film type. Its magnitude depends on dose: for 9 Gy increasing up to 14% at maximum lateral position. Cross talk was only significant in high contrast regions, up to 2% for very small fields. The optical path length effect introduced by film on the scanner causes 3% for pixels in the extreme lateral position. Light polarization due to film and the scanner's optical mirror system is the main contributor, different in magnitude for the red, green and blue channel. We concluded that any Gafchromic EBT type film scanned with a flatbed scanner will face these optical effects. Accurate dosimetry requires correction of LSE, therefore, determination of the LSE per color channel and dose delivered to the film.

  5. MRI of neuronal plasticity in rodent models.

    PubMed

    Pelled, Galit

    2011-01-01

    Modifications in the behavior and architecture of neuronal networks are well documented to occur in association with learning and memory, as well as following injury. These plasticity mechanisms are crucial to ensure adequate processing of stimuli, and they also dictate the degree of recovery following peripheral or central nervous system injury. Nevertheless, the underlying neuronal mechanisms that determine the degree of plasticity of neuronal pathways are not fully understood. Recent developments in animal-dedicated magnetic resonance imaging (MRI) scanners and related hardware afford a high spatial and temporal resolution, making functional MRI and manganese-enhanced MRI emerging tools for studying reorganization of neuronal pathways in rodent models. Many of the observed changes in neuronal functions in rodent's brains following injury discussed here agree with clinical human fMRI findings. This demonstrates that animal model imaging can have a significant clinical impact in the neuronal plasticity and rehabilitation arenas.

  6. Competitive advantage of PET/MRI.

    PubMed

    Jadvar, Hossein; Colletti, Patrick M

    2014-01-01

    Multimodality imaging has made great strides in the imaging evaluation of patients with a variety of diseases. Positron emission tomography/computed tomography (PET/CT) is now established as the imaging modality of choice in many clinical conditions, particularly in oncology. While the initial development of combined PET/magnetic resonance imaging (PET/MRI) was in the preclinical arena, hybrid PET/MR scanners are now available for clinical use. PET/MRI combines the unique features of MRI including excellent soft tissue contrast, diffusion-weighted imaging, dynamic contrast-enhanced imaging, fMRI and other specialized sequences as well as MR spectroscopy with the quantitative physiologic information that is provided by PET. Most evidence for the potential clinical utility of PET/MRI is based on studies performed with side-by-side comparison or software-fused MRI and PET images. Data on distinctive utility of hybrid PET/MRI are rapidly emerging. There are potential competitive advantages of PET/MRI over PET/CT. In general, PET/MRI may be preferred over PET/CT where the unique features of MRI provide more robust imaging evaluation in certain clinical settings. The exact role and potential utility of simultaneous data acquisition in specific research and clinical settings will need to be defined. It may be that simultaneous PET/MRI will be best suited for clinical situations that are disease-specific, organ-specific, related to diseases of the children or in those patients undergoing repeated imaging for whom cumulative radiation dose must be kept as low as reasonably achievable. PET/MRI also offers interesting opportunities for use of dual modality probes. Upon clear definition of clinical utility, other important and practical issues related to business operational model, clinical workflow and reimbursement will also be resolved. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  7. Uncertainty Propagation for Terrestrial Mobile Laser Scanner

    NASA Astrophysics Data System (ADS)

    Mezian, c.; Vallet, Bruno; Soheilian, Bahman; Paparoditis, Nicolas

    2016-06-01

    Laser scanners are used more and more in mobile mapping systems. They provide 3D point clouds that are used for object reconstruction and registration of the system. For both of those applications, uncertainty analysis of 3D points is of great interest but rarely investigated in the literature. In this paper we present a complete pipeline that takes into account all the sources of uncertainties and allows to compute a covariance matrix per 3D point. The sources of uncertainties are laser scanner, calibration of the scanner in relation to the vehicle and direct georeferencing system. We suppose that all the uncertainties follow the Gaussian law. The variances of the laser scanner measurements (two angles and one distance) are usually evaluated by the constructors. This is also the case for integrated direct georeferencing devices. Residuals of the calibration process were used to estimate the covariance matrix of the 6D transformation between scanner laser and the vehicle system. Knowing the variances of all sources of uncertainties, we applied uncertainty propagation technique to compute the variance-covariance matrix of every obtained 3D point. Such an uncertainty analysis enables to estimate the impact of different laser scanners and georeferencing devices on the quality of obtained 3D points. The obtained uncertainty values were illustrated using error ellipsoids on different datasets.

  8. Experimental characterization of the Clear-PEM scanner spectrometric performance

    NASA Astrophysics Data System (ADS)

    Bugalho, R.; Carriço, B.; Ferreira, C. S.; Frade, M.; Ferreira, M.; Moura, R.; Ortigão, C.; Pinheiro, J. F.; Rodrigues, P.; Rolo, I.; Silva, J. C.; Trindade, A.; Varela, J.

    2009-10-01

    In the framework of the Clear-PEM project for the construction of a high-resolution and high-specificity scanner for breast cancer imaging, a Positron Emission Mammography tomograph has been developed and installed at the Instituto Português de Oncologia do Porto hospital. The Clear-PEM scanner is mainly composed by two planar detector heads attached to a robotic arm, trigger/data acquisition electronics system and computing servers. The detector heads hold crystal matrices built from 2 × 2 × 20 mm3 LYSO:Ce crystals readout by Hamamatsu S8550 APD arrays. The APDs are optically coupled to both ends of the 6144 crystals in order to extract the DOI information for each detected event. Each one of 12288 APD's pixels is read and controlled by Application Specific Integrated Circuits water-cooled by an external cooling unit. The Clear-PEM frontend boards innovative design results in a unprecedented integration of the crystal matrices, APDs and ASICs, making Clear-PEM the PET scanner with the highest number of APD pixels ever integrated so far. In this paper, the scanner's main technical characteristics, calibration strategies and the first spectrometric performance evaluation in a clinical environment are presented. The first commissioning results show 99.7% active channels, which, after calibration, have inter-pixel and absolute gain distributions with dispersions of, respectively, 12.2% and 15.3%, demonstrating that despite the large number of channels, the system is uniform. The mean energy resolution at 511 keV is of 15.9%, with a 8.8% dispersion, and the mean CDOI-1 is 5.9%/mm, with a 7.8% dispersion. The coincidence time resolution, at 511 keV, for a energy window between 400 and 600 keV, is 5.2 ns FWHM.

  9. Monte Carlo-based noise compensation in coil intensity corrected endorectal MRI.

    PubMed

    Lui, Dorothy; Modhafar, Amen; Haider, Masoom A; Wong, Alexander

    2015-10-12

    Prostate cancer is one of the most common forms of cancer found in males making early diagnosis important. Magnetic resonance imaging (MRI) has been useful in visualizing and localizing tumor candidates and with the use of endorectal coils (ERC), the signal-to-noise ratio (SNR) can be improved. The coils introduce intensity inhomogeneities and the surface coil intensity correction built into MRI scanners is used to reduce these inhomogeneities. However, the correction typically performed at the MRI scanner level leads to noise amplification and noise level variations. In this study, we introduce a new Monte Carlo-based noise compensation approach for coil intensity corrected endorectal MRI which allows for effective noise compensation and preservation of details within the prostate. The approach accounts for the ERC SNR profile via a spatially-adaptive noise model for correcting non-stationary noise variations. Such a method is useful particularly for improving the image quality of coil intensity corrected endorectal MRI data performed at the MRI scanner level and when the original raw data is not available. SNR and contrast-to-noise ratio (CNR) analysis in patient experiments demonstrate an average improvement of 11.7 and 11.2 dB respectively over uncorrected endorectal MRI, and provides strong performance when compared to existing approaches. Experimental results using both phantom and patient data showed that ACER provided strong performance in terms of SNR, CNR, edge preservation, subjective scoring when compared to a number of existing approaches. A new noise compensation method was developed for the purpose of improving the quality of coil intensity corrected endorectal MRI data performed at the MRI scanner level. We illustrate that promising noise compensation performance can be achieved for the proposed approach, which is particularly important for processing coil intensity corrected endorectal MRI data performed at the MRI scanner level and when the

  10. [MRI of the prostate: optimization of imaging protocols].

    PubMed

    Rouvière, O

    2006-02-01

    This article details the imaging protocols for prostate MRI and the influence on image quality of each particular setting: type of coils to be used (endorectal or external phased-array coils?), patient preparation, type of sequences, spatial resolution parameters. The principle and technical constraints of dynamic contrast-enhanced MRI are also presented, as well as the predictable changes due to the introduction of high-field strength (3T) scanners.

  11. Computed Tomography and MRI of the Hepatobiliary System and Pancreas.

    PubMed

    Marolf, Angela J

    2016-05-01

    MRI and computed tomographic (CT) imaging are becoming more common in the diagnosis of hepatobiliary and pancreatic disorders in small animals. With the advent of multislice CT scanners, sedated examinations in veterinary patients are feasible increasing the use of this imaging modality. CT and MRI provide additional information for dogs and cats with hepatobiliary and pancreatic diseases because of lack of superimposition of structures, operator dependence, and through intravenous contrast administration. This added value provides more information for diagnosis, prognosis, and surgical planning.

  12. MRI Compatibility of Microfabricated Magnetic Actuators for Implantable Catheters: Mechanical Evaluations

    PubMed Central

    Lee, Hyowon; Xu, Qing; Ephrati, Jeremy; Bergsneider, Marvin; Judy, Jack W.

    2017-01-01

    Here we demonstrate the mechanical robustness of microfabricated torsional magnetic actuators in withstanding the magnetic fields produced by a 7 T MRI magnet. The static and dynamic mechanical characteristics of 30 devices were quantitatively measured before and after exposure to both uniform and non-uniform magnetic fields. The results show no statistically significant change in both the static and dynamic mechanical performance, which mitigates concerns about the mechanical compatibility of our devices with MRI scanners. Additional experiments are required to quantify the potential image-artifact size and radio-frequency-induced heating caused by the magnetic microactuators inside an MRI scanner. PMID:21096979

  13. A PDMS-Based 2-Axis Waterproof Scanner for Photoacoustic Microscopy

    PubMed Central

    Kim, Jin Young; Lee, Changho; Park, Kyungjin; Lim, Geunbae; Kim, Chulhong

    2015-01-01

    Optical-resolution photoacoustic microscopy (OR-PAM) is an imaging tool to provide in vivo optically sensitive images in biomedical research. To achieve a small size, fast imaging speed, wide scan range, and high signal-to-noise ratios (SNRs) in a water environment, we introduce a polydimethylsiloxane (PDMS)-based 2-axis scanner for a flexible and waterproof structure. The design, theoretical background, fabrication process and performance of the scanner are explained in details. The designed and fabricated scanner has dimensions of 15 × 15 × 15 mm along the X, Y and Z axes, respectively. The characteristics of the scanner are tested under DC and AC conditions. By pairing with electromagnetic forces, the maximum scanning angles in air and water are 18° and 13° along the X and Y axes, respectively. The measured resonance frequencies in air and water are 60 and 45 Hz along the X axis and 45 and 30 Hz along the Y axis, respectively. Finally, OR-PAM with high SNRs is demonstrated using the fabricated scanner, and the PA images of micro-patterned samples and microvasculatures of a mouse ear are successfully obtained with high-resolution and wide-field of view. OR-PAM equipped with the 2-axis PDMS based waterproof scanner has lateral and axial resolutions of 3.6 μm and 26 μm, respectively. This compact OR-PAM system could potentially and widely be used in preclinical and clinical applications. PMID:25923931

  14. Three-dimensional surface scanners compared with standard anthropometric measurements for head shape.

    PubMed

    Beaumont, Caroline A A; Knoops, Paul G M; Borghi, Alessandro; Jeelani, N U Owase; Koudstaal, Maarten J; Schievano, Silvia; Dunaway, David J; Rodriguez-Florez, Naiara

    2017-06-01

    Three-dimensional (3D) surface imaging devices designed to capture and quantify craniofacial surface morphology are becoming more common in clinical environments. Such scanners overcome the limitations of two-dimensional photographs while avoiding the ionizing radiation of computed tomography. The purpose of this study was to compare standard anthropometric cranial measurements with measurements taken from images acquired with 3D surface scanners. Two 3D scanners of different cost were used to acquire head shape data from thirteen adult volunteers: M4D scan and Structure Sensor. Head circumference and cephalic index were measured directly on the patients as well as on 3D scans acquired with the two scanners. To compare head volume measurements with a gold standard, magnetic resonance imaging scans were used. Repeatability and accuracy of both devices were evaluated. Intra-rater repeatability for both scanners was excellent (intraclass correlation coefficients > 0.99, p < 0.001). Direct and digital measures of head circumference, cephalic index and head volume were strongly correlated (0.85 < r < 0.91, p < 0.001). Compared to direct measurements, accuracy was highest for M4D scan. Both 3D scanners provide reproducible data of head circumference, cephalic index and head volume and show a strong correlation with traditional measurements. However, care must be taken when using absolute values. Copyright © 2017 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

  15. MEMS temperature scanner: principles, advances, and applications

    NASA Astrophysics Data System (ADS)

    Otto, Thomas; Saupe, Ray; Stock, Volker; Gessner, Thomas

    2010-02-01

    Contactless measurement of temperatures has gained enormous significance in many application fields, ranging from climate protection over quality control to object recognition in public places or military objects. Thereby measurement of linear or spatially temperature distribution is often necessary. For this purposes mostly thermographic cameras or motor driven temperature scanners are used today. Both are relatively expensive and the motor drive devices are limited regarding to the scanning rate additionally. An economic alternative are temperature scanner devices based on micro mirrors. The micro mirror, attached in a simple optical setup, reflects the emitted radiation from the observed heat onto an adapted detector. A line scan of the target object is obtained by periodic deflection of the micro scanner. Planar temperature distribution will be achieved by perpendicularly moving the target object or the scanner device. Using Planck radiation law the temperature of the object is calculated. The device can be adapted to different temperature ranges and resolution by using different detectors - cooled or uncooled - and parameterized scanner parameters. With the basic configuration 40 spatially distributed measuring points can be determined with temperatures in a range from 350°C - 1000°C. The achieved miniaturization of such scanners permits the employment in complex plants with high building density or in direct proximity to the measuring point. The price advantage enables a lot of applications, especially new application in the low-price market segment This paper shows principle, setup and application of a temperature measurement system based on micro scanners working in the near infrared range. Packaging issues and measurement results will be discussed as well.

  16. TU-G-201-02: An MRI Simulator From Proposal to Operation

    SciTech Connect

    Cao, Y.

    2015-06-15

    This session will update therapeutic physicists on technological advancements and radiation oncology features of commercial CT, MRI, and PET/CT imaging systems. Also described are physicists’ roles in every stage of equipment selection, purchasing, and operation, including defining specifications, evaluating vendors, making recommendations, and optimal and safe use of imaging equipment in radiation oncology environment. The first presentation defines important terminology of CT and PET/CT followed by a review of latest innovations, such as metal artifact reduction, statistical iterative reconstruction, radiation dose management, tissue classification by dual energy CT and spectral CT, improvement in spatial resolution and sensitivity in PET, and potentials of PET/MR. We will also discuss important technical specifications and items in CT and PET/CT purchasing quotes and their impacts. The second presentation will focus on key components in the request for proposal for a MRI simulator and how to evaluate vendor proposals. MRI safety issues in radiation Oncology, including MRI scanner Zones (4-zone design), will be discussed. Basic MR terminologies, important functionalities, and advanced features, which are relevant to radiation therapy, will be discussed. In the third presentation, justification of imaging systems for radiation oncology, considerations in room design and construction in a RO department, shared use with diagnostic radiology, staffing needs and training, clinical/research use cases and implementation, will be discussed. The emphasis will be on understanding and bridging the differences between diagnostic and radiation oncology installations, building consensus amongst stakeholders for purchase and use, and integrating imaging technologies into the radiation oncology environment. Learning Objectives: Learn the latest innovations of major imaging systems relevant to radiation therapy Be able to describe important technical specifications of CT, MRI

  17. MRI compatibility of robot actuation techniques--a comparative study.

    PubMed

    Fischer, Gregory S; Krieger, Axel; Iordachita, Iulian; Csoma, Csaba; Whitcomb, Louis L; Gabor, Fichtinger

    2008-01-01

    This paper reports an experimental evaluation of the following three different MRI-compatible actuators: a Shinsei ultrasonic motor a Nanomotion ultrasonic motor and a pneumatic cylinder actuator. We report the results of a study comparing the effect of these actuators on the signal to noise ratio (SNR) of MRJ images under a variety of experimental conditions. Evaluation was performed with the controller inside and outside the scanner room and with both 1.5T and 3T MRI scanners. Pneumatic cylinders function with no loss of SNR with controller both inside and outside of the scanner room. The Nanomotion motor performs with moderate loss of SNR when moving during imaging. The Shinsei is unsuitable for motion during imaging. All may be used when motion is appropriately interleaved with imaging cycles.

  18. Auditory intensity processing: Effect of MRI background noise.

    PubMed

    Angenstein, Nicole; Stadler, Jörg; Brechmann, André

    2016-03-01

    Studies on active auditory intensity discrimination in humans showed equivocal results regarding the lateralization of processing. Whereas experiments with a moderate background found evidence for right lateralized processing of intensity, functional magnetic resonance imaging (fMRI) studies with background scanner noise suggest more left lateralized processing. With the present fMRI study, we compared the task dependent lateralization of intensity processing between a conventional continuous echo planar imaging (EPI) sequence with a loud background scanner noise and a fast low-angle shot (FLASH) sequence with a soft background scanner noise. To determine the lateralization of the processing, we employed the contralateral noise procedure. Linearly frequency modulated (FM) tones were presented monaurally with and without contralateral noise. During both the EPI and the FLASH measurement, the left auditory cortex was more strongly involved than the right auditory cortex while participants categorized the intensity of FM tones. This was shown by a strong effect of the additional contralateral noise on the activity in the left auditory cortex. This means a massive reduction in background scanner noise still leads to a significant left lateralized effect. This suggests that the reversed lateralization in fMRI studies with loud background noise in contrast to studies with softer background cannot be fully explained by the MRI background noise. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Knee MRI

    MedlinePlus

    ... magnetic field of the MRI unit, metal and electronic items are not allowed in the exam room. ... tell the technologist if you have medical or electronic devices in your body. These objects may interfere ...

  20. Shoulder MRI

    MedlinePlus

    ... magnetic field of the MRI unit, metal and electronic items are not allowed in the exam room. ... tell the technologist if you have medical or electronic devices in your body. These objects may interfere ...

  1. Shoulder MRI

    MedlinePlus

    ... of the shoulder uses a powerful magnetic field, radio waves and a computer to produce detailed pictures of ... scans, MRI does not utilize ionizing radiation. Instead, radio waves redirect alignment of hydrogen atoms that naturally exist ...

  2. Knee MRI

    MedlinePlus

    ... of the knee uses a powerful magnetic field, radio waves and a computer to produce detailed pictures of ... scans, MRI does not utilize ionizing radiation. Instead, radio waves redirect alignment of hydrogen atoms that naturally exist ...

  3. LANSCE-R WIRE-SCANNER SYSTEM

    SciTech Connect

    Gruchalla, Michael E.

    2011-01-01

    The National Instruments cRIO platform is used for the new LANSCE-R wire-scanner systems. All wire-scanner electronics are integrated into a single BiRa BiRIO 4U cRIO chassis specifically designed for the cRIO crate and all interface electronics. The BiRIO chassis, actuator and LabVIEW VIs provide a complete wire-scanner system integrated with EPICS. The new wire-scanner chassis includes an 8-slot cRIO crate with Virtex-5 LX 110 FPGA and Power-PC real-time controller, the LANL-developed cRIO 2-axis wire-sensor analog interface module (AFE), NI9222 cRIO 4-channel 16-bit digitizer, cRIO resolver demodulator, cRIO event receiver, front-panel touch panel display, motor driver, and all necessary software, interface wiring, connectors and ancillary components. This wirescanner system provides a complete, turn-key, 2-axis wire-scanner system including 2-channel low-noise sensewire interface with variable DC wire bias and wireintegrity monitor, 16-bit signal digitizers, actuator motor drive and control, actuator position sensing, limit-switch interfaces, event receiver, LabVIEW and EPICS interface, and both remote operation and full stand-alone operation using the touch panel.

  4. Cognition for robot scanner based remote welding

    NASA Astrophysics Data System (ADS)

    Thombansen, U.; Ungers, Michael

    2014-02-01

    The effort for reduced cycle times in manufacturing has supported the development of remote welding systems which use a combination of scanners for beam delivery and robots for scanner positioning. Herein, close coupling of both motions requires a precise command of the robot trajectory and the scanner positioning to end up with a combined beam delivery. Especially the path precision of the robot plays a vital role in this kinematic chain. In this paper, a sensor system is being presented which allows tracking the motion of the laser beam against the work piece. It is based on a camera system which is coaxially connected to the scanner thus observing the relative motion of the laser beam relative to the work piece. The acquired images are processed with computer vision algorithms from the field of motion detection. The suitability of the algorithms is being demonstrated with a motion tracking tool which visualizes the homogeneity of the tracking result. The reported solution adds cognitive capabilities to manufacturing systems for robot scanner based materials processing. It allows evaluation of the relative motion between work piece and the laser beam. Moreover, the system can be used to adapt system programming during set-up of a manufacturing task or to evaluate the functionality of a manufacturing system during production. The presented sensor system will assist in optimizing manufacturing processes.

  5. Multichannel Compressive Sensing MRI Using Noiselet Encoding

    PubMed Central

    Pawar, Kamlesh; Egan, Gary; Zhang, Jingxin

    2015-01-01

    The incoherence between measurement and sparsifying transform matrices and the restricted isometry property (RIP) of measurement matrix are two of the key factors in determining the performance of compressive sensing (CS). In CS-MRI, the randomly under-sampled Fourier matrix is used as the measurement matrix and the wavelet transform is usually used as sparsifying transform matrix. However, the incoherence between the randomly under-sampled Fourier matrix and the wavelet matrix is not optimal, which can deteriorate the performance of CS-MRI. Using the mathematical result that noiselets are maximally incoherent with wavelets, this paper introduces the noiselet unitary bases as the measurement matrix to improve the incoherence and RIP in CS-MRI. Based on an empirical RIP analysis that compares the multichannel noiselet and multichannel Fourier measurement matrices in CS-MRI, we propose a multichannel compressive sensing (MCS) framework to take the advantage of multichannel data acquisition used in MRI scanners. Simulations are presented in the MCS framework to compare the performance of noiselet encoding reconstructions and Fourier encoding reconstructions at different acceleration factors. The comparisons indicate that multichannel noiselet measurement matrix has better RIP than that of its Fourier counterpart, and that noiselet encoded MCS-MRI outperforms Fourier encoded MCS-MRI in preserving image resolution and can achieve higher acceleration factors. To demonstrate the feasibility of the proposed noiselet encoding scheme, a pulse sequences with tailored spatially selective RF excitation pulses was designed and implemented on a 3T scanner to acquire the data in the noiselet domain from a phantom and a human brain. The results indicate that noislet encoding preserves image resolution better than Fouirer encoding. PMID:25965548

  6. Multichannel compressive sensing MRI using noiselet encoding.

    PubMed

    Pawar, Kamlesh; Egan, Gary; Zhang, Jingxin

    2015-01-01

    The incoherence between measurement and sparsifying transform matrices and the restricted isometry property (RIP) of measurement matrix are two of the key factors in determining the performance of compressive sensing (CS). In CS-MRI, the randomly under-sampled Fourier matrix is used as the measurement matrix and the wavelet transform is usually used as sparsifying transform matrix. However, the incoherence between the randomly under-sampled Fourier matrix and the wavelet matrix is not optimal, which can deteriorate the performance of CS-MRI. Using the mathematical result that noiselets are maximally incoherent with wavelets, this paper introduces the noiselet unitary bases as the measurement matrix to improve the incoherence and RIP in CS-MRI. Based on an empirical RIP analysis that compares the multichannel noiselet and multichannel Fourier measurement matrices in CS-MRI, we propose a multichannel compressive sensing (MCS) framework to take the advantage of multichannel data acquisition used in MRI scanners. Simulations are presented in the MCS framework to compare the performance of noiselet encoding reconstructions and Fourier encoding reconstructions at different acceleration factors. The comparisons indicate that multichannel noiselet measurement matrix has better RIP than that of its Fourier counterpart, and that noiselet encoded MCS-MRI outperforms Fourier encoded MCS-MRI in preserving image resolution and can achieve higher acceleration factors. To demonstrate the feasibility of the proposed noiselet encoding scheme, a pulse sequences with tailored spatially selective RF excitation pulses was designed and implemented on a 3T scanner to acquire the data in the noiselet domain from a phantom and a human brain. The results indicate that noislet encoding preserves image resolution better than Fouirer encoding.

  7. Scanner identification with extension to forgery detection

    NASA Astrophysics Data System (ADS)

    Khanna, Nitin; Chiu, George T. C.; Allebach, Jan P.; Delp, Edward J.

    2008-02-01

    Digital images can be obtained through a variety of sources including digital cameras and scanners. With rapidly increasing functionality and ease of use of image editing software, determining authenticity and identifying forged regions, if any, is becoming crucial for many applications. This paper presents methods for authenticating and identifying forged regions in images that have been acquired using flatbed scanners. The methods are based on using statistical features of imaging sensor pattern noise as a fingerprint for the scanner. An anisotropic local polynomial estimator is used for obtaining the noise patterns. A SVM classifier is trained for using statistical features of pattern noise for classifying smaller blocks of an image. This feature vector based approach is shown to identify the forged regions with high accuracy.

  8. CT densitometry of the lungs: Scanner performance

    SciTech Connect

    Kemerink, G.J.; Lamers, R.J.S.; Thelissen, G.R.P.; Engelshoven, J.M.A. van

    1996-01-01

    Our goal was to establish the reproducibility and accuracy of the CT scanner in densitometry of the lungs. Scanner stability was assessed by analysis of daily quality checks. Studies using a humanoid phantom and polyethylene foams for lung were performed to measure reproducibility and accuracy. The dependence of the CT-estimated density on reconstruction filter, zoom factor, slice thickness, table height, data truncation, and objects outside the scan field was determined. Stability of the system at air density was within {approx}1 HU and at water density within {approx}2 HU. Reproducibility and accuracy for densities found for lung were within 2-3%. Dependence on the acquisition and reconstruction parameters was neglible, with the exceptions of the ultra high resolution reconstruction algorithm in the case of emphysema, and objects outside the scan field. The performance of the CT scanner tested is quite adequate for densitometry of the lungs. 26 refs., 5 figs., 4 tabs.

  9. A flexible and wearable terahertz scanner

    NASA Astrophysics Data System (ADS)

    Suzuki, D.; Oda, S.; Kawano, Y.

    2016-12-01

    Imaging technologies based on terahertz (THz) waves have great potential for use in powerful non-invasive inspection methods. However, most real objects have various three-dimensional curvatures and existing THz technologies often encounter difficulties in imaging such configurations, which limits the useful range of THz imaging applications. Here, we report the development of a flexible and wearable THz scanner based on carbon nanotubes. We achieved room-temperature THz detection over a broad frequency band ranging from 0.14 to 39 THz and developed a portable THz scanner. Using this scanner, we performed THz imaging of samples concealed behind opaque objects, breakages and metal impurities of a bent film and multi-view scans of a syringe. We demonstrated a passive biometric THz scan of a human hand. Our results are expected to have considerable implications for non-destructive and non-contact inspections, such as medical examinations for the continuous monitoring of health conditions.

  10. How flatbed scanners upset accurate film dosimetry

    NASA Astrophysics Data System (ADS)

    van Battum, L. J.; Huizenga, H.; Verdaasdonk, R. M.; Heukelom, S.

    2016-01-01

    Film is an excellent dosimeter for verification of dose distributions due to its high spatial resolution. Irradiated film can be digitized with low-cost, transmission, flatbed scanners. However, a disadvantage is their lateral scan effect (LSE): a scanner readout change over its lateral scan axis. Although anisotropic light scattering was presented as the origin of the LSE, this paper presents an alternative cause. Hereto, LSE for two flatbed scanners (Epson 1680 Expression Pro and Epson 10000XL), and Gafchromic film (EBT, EBT2, EBT3) was investigated, focused on three effects: cross talk, optical path length and polarization. Cross talk was examined using triangular sheets of various optical densities. The optical path length effect was studied using absorptive and reflective neutral density filters with well-defined optical characteristics (OD range 0.2-2.0). Linear polarizer sheets were used to investigate light polarization on the CCD signal in absence and presence of (un)irradiated Gafchromic film. Film dose values ranged between 0.2 to 9 Gy, i.e. an optical density range between 0.25 to 1.1. Measurements were performed in the scanner’s transmission mode, with red-green-blue channels. LSE was found to depend on scanner construction and film type. Its magnitude depends on dose: for 9 Gy increasing up to 14% at maximum lateral position. Cross talk was only significant in high contrast regions, up to 2% for very small fields. The optical path length effect introduced by film on the scanner causes 3% for pixels in the extreme lateral position. Light polarization due to film and the scanner’s optical mirror system is the main contributor, different in magnitude for the red, green and blue channel. We concluded that any Gafchromic EBT type film scanned with a flatbed scanner will face these optical effects. Accurate dosimetry requires correction of LSE, therefore, determination of the LSE per color channel and dose delivered to the film.

  11. Miniature rotating transmissive optical drum scanner

    NASA Technical Reports Server (NTRS)

    Lewis, Robert (Inventor); Parrington, Lawrence (Inventor); Rutberg, Michael (Inventor)

    2013-01-01

    A miniature rotating transmissive optical scanner system employs a drum of small size having an interior defined by a circumferential wall rotatable on a drum axis, an optical element positioned within the interior of the drum, and a light-transmissive lens aperture provided at an angular position in the circumferential wall of the drum for scanning a light beam to or from the optical element in the drum along a beam azimuth angle as the drum is rotated. The miniature optical drum scanner configuration obtains a wide scanning field-of-view (FOV) and large effective aperture is achieved within a physically small size.

  12. Multispectral scanner imagery for plant community classification.

    NASA Technical Reports Server (NTRS)

    Driscoll, R. S.; Spencer, M. M.

    1973-01-01

    Optimum channel selection among 12 channels of multispectral scanner imagery identified six as providing the best information for computerized classification of 11 plant communities and two nonvegetation classes. Intensive preprocessing of the spectral data was required to eliminate bidirectional reflectance effects of the spectral imagery caused by scanner view angle and varying geometry of the plant canopy. Generalized plant community types - forest, grassland, and hydrophytic systems - were acceptably classified based on ecological analysis. Serious, but soluble, errors occurred with attempts to classify specific community types within the grassland system. However, special clustering analyses provided for improved classification of specific grassland communities.

  13. Bone mineral computation with a rectilinear scanner

    NASA Technical Reports Server (NTRS)

    Ullman, J.; Brown, S.; Silverstein, A.; Vogel, J. M.

    1974-01-01

    A portable rectilinear transmission scanner and associated computerized data reduction techniques for estimating bone mineral content are described. This unit can be easily disassembled for transport to various measurement sites and has been used to estimate the bone mineral content of the os calcis, radius, and ulna in the Apollo and Skylab astronauts. The scanner is used to obtain multiple rows of data from which a bone profile is derived. Bone edges are determined with the aid of a digital computer program which employs an algorithm that determines the greatest rate of change of the counting rate.

  14. Multispectral scanner imagery for plant community classification.

    NASA Technical Reports Server (NTRS)

    Driscoll, R. S.; Spencer, M. M.

    1973-01-01

    Optimum channel selection among 12 channels of multispectral scanner imagery identified six as providing the best information for computerized classification of 11 plant communities and two nonvegetation classes. Intensive preprocessing of the spectral data was required to eliminate bidirectional reflectance effects of the spectral imagery caused by scanner view angle and varying geometry of the plant canopy. Generalized plant community types - forest, grassland, and hydrophytic systems - were acceptably classified based on ecological analysis. Serious, but soluble, errors occurred with attempts to classify specific community types within the grassland system. However, special clustering analyses provided for improved classification of specific grassland communities.

  15. Experiment research on orthogonal tilting scanner

    NASA Astrophysics Data System (ADS)

    Li, Anhu; Liu, Liren; Sun, Jianfeng; Zhong, Xianghong; Luan, Zhu

    2007-09-01

    The original scanner of tilting orthogonal double prisms is studied for testing the tracking performance in inter-satellite laser communications. Two prisms respectively rotate around the horizontal axle and the vertical one within the admissible range to determine the corresponding orientation and position of the passing beam, therefore the high accuracy deviation angle of passing beam can be performed. The test experiments performed with autocollimator and interferometer, as well as the theoretical analysis, indicates that the scanner can meet the requirements of the deviation accuracy superior to 0.5 μrad with the deviation range greater than 500 μrad, which accords to our design requirements.

  16. LANSCE Wire Scanner System Prototype: Switchyard Test

    SciTech Connect

    Sedillo, James D

    2012-04-11

    On November 19, 2011, the beam diagnostics team of Los Alamos National Laboratory's LANSCE accelerator facility conducted a test of a prototype wire scanner system for future deployment within the accelerator's switchyard area. The primary focus of this test was to demonstrate the wire scanner control system's ability to extend its functionality beyond acquiring lower energy linac beam profile measurements to acquiring data in the switchyard. This study summarizes the features and performance characteristics of the electronic and mechanical implementation of this system with details focusing on the test results.

  17. Infrared scanner concept verification test report

    NASA Technical Reports Server (NTRS)

    Bachtel, F. D.

    1980-01-01

    The test results from a concept verification test conducted to assess the use of an infrared scanner as a remote temperature sensing device for the space shuttle program are presented. The temperature and geometric resolution limits, atmospheric attenuation effects including conditions with fog and rain, and the problem of surface emissivity variations are included. It is concluded that the basic concept of using an infrared scanner to determine near freezing surface temperatures is feasible. The major problem identified is concerned with infrared reflections which result in significant errors if not controlled. Action taken to manage these errors result in design and operational constraints to control the viewing angle and surface emissivity.

  18. The conical scanner evaluation system design

    NASA Technical Reports Server (NTRS)

    Cumella, K. E.; Bilanow, S.; Kulikov, I. B.

    1982-01-01

    The software design for the conical scanner evaluation system is presented. The purpose of this system is to support the performance analysis of the LANDSAT-D conical scanners, which are infrared horizon detection attitude sensors designed for improved accuracy. The system consists of six functionally independent subsystems and five interface data bases. The system structure and interfaces of each of the subsystems is described and the content, format, and file structure of each of the data bases is specified. For each subsystem, the functional logic, the control parameters, the baseline structure, and each of the subroutines are described. The subroutine descriptions include a procedure definition and the input and output parameters.

  19. Function biomedical informatics research network recommendations for prospective multicenter functional MRI studies.

    PubMed

    Glover, Gary H; Mueller, Bryon A; Turner, Jessica A; van Erp, Theo G M; Liu, Thomas T; Greve, Douglas N; Voyvodic, James T; Rasmussen, Jerod; Brown, Gregory G; Keator, David B; Calhoun, Vince D; Lee, Hyo Jong; Ford, Judith M; Mathalon, Daniel H; Diaz, Michele; O'Leary, Daniel S; Gadde, Syam; Preda, Adrian; Lim, Kelvin O; Wible, Cynthia G; Stern, Hal S; Belger, Aysenil; McCarthy, Gregory; Ozyurt, Burak; Potkin, Steven G

    2012-07-01

    This report provides practical recommendations for the design and execution of multicenter functional MRI (MC-fMRI) studies based on the collective experience of the Function Biomedical Informatics Research Network (FBIRN). The study was inspired by many requests from the fMRI community to FBIRN group members for advice on how to conduct MC-fMRI studies. The introduction briefly discusses the advantages and complexities of MC-fMRI studies. Prerequisites for MC-fMRI studies are addressed before delving into the practical aspects of carefully and efficiently setting up a MC-fMRI study. Practical multisite aspects include: (i) establishing and verifying scan parameters including scanner types and magnetic fields, (ii) establishing and monitoring of a scanner quality program, (iii) developing task paradigms and scan session documentation, (iv) establishing clinical and scanner training to ensure consistency over time, (v) developing means for uploading, storing, and monitoring of imaging and other data, (vi) the use of a traveling fMRI expert, and (vii) collectively analyzing imaging data and disseminating results. We conclude that when MC-fMRI studies are organized well with careful attention to unification of hardware, software and procedural aspects, the process can be a highly effective means for accessing a desired participant demographics while accelerating scientific discovery.

  20. Slice profile distortions in single slice continuously moving table MRI

    NASA Astrophysics Data System (ADS)

    Sengupta, Saikat; Smith, David S.; Welch, E. B.

    2015-03-01

    Continuously Moving Table (CMT) MRI is a rapid imaging technique that allows scanning of extended fields of view (FOVs) such as the whole-body in a single continuous scan.1 A highly efficient approach to CMT MRI is single slice imaging, where data are continuously acquired from a single axial slice at isocenter with concurrent movement of the patient table.2 However, the continuous motion of the scanner table and supply of fresh magnetization into the excited slice can introduce deviations in the slice magnetization profile. The goal of this work is to investigate and quantify the distortion in the slice profile in CMT MRI. CMT MRI with a table speed of 20 mm/s was implemented on a 3 Tesla whole-body MRI scanner, with continuous radial data acquisition. Simulations were performed to characterize the transient and steady state slice profiles and magnetization effects. Simulated slice profiles were compared to actual slice profile measurements performed in the scanner. Both simulations and experiments revealed an asymmetric slice profile characterized by a skew towards the lagging edge of the moving table, in contrast to the nominal profiles associated with scanning a stationary object. The true excited slice width (FWHM) and pitch of the acquisition was observed to be dependent on table velocity, with larger table speeds resulting in larger slice profile deviations from the nominal shape.

  1. Women are more strongly affected by dizziness in static magnetic fields of magnetic resonance imaging scanners.

    PubMed

    Heinrich, Angela; Szostek, Anne; Meyer, Patric; Reinhard, Iris; Gilles, Maria; Paslakis, Georgios; Rauschenberg, Jaane; Gröbner, Jens; Semmler, Wolfhard; Deuschle, Michael; Meyer-Lindenberg, Andreas; Flor, Herta; Nees, Frauke

    2014-10-01

    Increasing field strengths in MRI necessitate the examination of potential side effects. Previously reported results have been contradictory, possibly caused by imbalanced samples. We aimed to examine whether special groups of people are more prone to develop side effects that might have led to contradictory results in previous studies. We examined the occurrence of sensory side effects in static magnetic fields of MRI scanners of 1.5, 3, and 7 T and a mock scanner in 41 healthy participants. The contribution of field strength, sex, age, and attention to bodily processes, and stress hormone levels to the sensation of dizziness was examined in separate univariate analyses and in a joint analysis that included all variables. Field strength and sex were significant factors in the joint analysis (P=0.001), with women being more strongly affected than men by dizziness in higher static magnetic fields. This effect was not mediated by the other variables such as attention to bodily symptoms or stress hormones. Further research needs to elucidate the underlying factors of increased dizziness in women in static magnetic fields in MRI. We hypothesize that imbalanced samples of earlier studies might be one reason for previous contradictory results on the side effects of static magnetic fields.

  2. Calorimetric calibration of head coil SAR estimates displayed on a clinical MR scanner.

    PubMed

    Gorny, Krzysztof R; Bernstein, Matt A; Felmlee, Joel P; Ward, Heidi A; McGee, Kiaran P; Lanners, Diana M; Lee, Kendall H

    2008-05-21

    Calorimetric measurements were performed to determine the average specific absorption rates (SAR) resulting from MRI head examinations. The data were compared with average head coil SAR estimates displayed by the MR scanner in order to refine the imaging protocols used in imaging patients with implanted deep brain stimulators (DBS). The experiments were performed using transmit-receive (TR) head coil on clinical 1.5 T General Electric MR scanners running 11.0 M4 revision software. The average applied SAR was derived from temperature increases measured inside a head phantom, due to deposition of RF energy during MRI scanning with a spin echo imaging sequence. The measurements were repeated for varied levels of RF transmit gain (TG) and analyzed with a range of entered patient weights. The measurements demonstrate that the ratio of the actual average head SAR to the scanner-displayed value (coil correction factor) decreases for decreasing TG or for increasing patient weight and may vary between 0.3 and 2.1. An additional retrospective patient study, however, shows that not all combinations of TG and patient weight are encountered clinically and, instead, TG generally increases with the patient weight. As a result, a much narrower range of coil correction factors (e.g., typically 0.5-1.0) will be encountered in practice. The calorimetric method described in this work could aid the physicians and technologists in refinement of the model-dependent SAR estimates displayed by the MR scanner, and in selection of imaging parameters for MR head examinations within allowable SAR safety levels.

  3. Portable MRI

    SciTech Connect

    Espy, Michelle A.

    2012-06-29

    This project proposes to: (1) provide the power of MRI to situations where it presently isn't available; (2) perform the engineering required to move from lab to a functional prototype; and (3) leverage significant existing infrastructure and capability in ultra-low field MRI. The reasons for doing this: (1) MRI is the most powerful tool for imaging soft-tissue (e.g. brain); (2) Billions don't have access due to cost or safety issues; (3) metal will heat/move in high magnetic fields; (4) Millions of cases of traumatic brain injury in US alone; (5) even more of non-traumatic brain injury; (6) (e.g. stroke, infection, chemical exposure); (7) Need for early diagnostic; (8) 'Signature' wound of recent conflicts; (9) 22% of injuries; (10) Implications for post-traumatic stress disorder; and (11) chronic traumatic encephalopathy.

  4. Towards Truly Quiet MRI: animal MRI magnetic field gradients as a test platform for acoustic noise reduction

    NASA Astrophysics Data System (ADS)

    Edelstein, William; El-Sharkawy, Abdel-Monem

    2013-03-01

    Clinical MRI acoustic noise, often substantially exceeding 100 dB, causes patient anxiety and discomfort and interferes with functional MRI (fMRI) and interventional MRI. MRI acoustic noise reduction is a long-standing and difficult technical challenge. The noise is basically caused by large Lorentz forces on gradient windings--surrounding the patient bore--situated in strong magnetic fields (1.5 T, 3 T or higher). Pulsed currents of 300 A or more are switched through the gradient windings in sub-milliseconds. Experimenting with hardware noise reduction on clinical scanners is difficult and expensive because of the large scale and weight of clinical scanner components (gradient windings ~ 1000 kg) that require special handling equipment in large engineering test facilities. Our approach is to produce a Truly Quiet (<70 dB) small-scale animal imager. Results serve as a test platform for acoustic noise reduction measures that can be implemented in clinical scanners. We have so far decreased noise in an animal scale imager from 108 dB to 71 dB, a 37 dB reduction. Our noise reduction measures include: a gradient container that can be evacuated; inflatable antivibration mounts to prevent transmission of vibrations from gradient winding to gradient container; vibration damping of wires going from gradient to the outside world via the gradient container; and a copper passive shield to prevent the generation of eddy currents in the metal cryostat inner bore, which in turn can vibrate and produce noise.

  5. Miniature 'Wearable' PET Scanner Ready for Use

    ScienceCinema

    Paul Vaska

    2016-07-12

    Scientists from BNL, Stony Brook University, and collaborators have demonstrated the efficacy of a "wearable," portable PET scanner they've developed for rats. The device will give neuroscientists a new tool for simultaneously studying brain function and behavior in fully awake, moving animals.

  6. Ultrasonic Scanner Control and Data Acquisition

    NASA Technical Reports Server (NTRS)

    Hemann, John

    2002-01-01

    The research accomplishments under this grant were very extensive in the areas of ULTRASONIC SCANNER CONTROL AND DATA ACQUISITION. Rather than try to summarize all this research I have enclosed research papers and reports which were completed with the hnding provided by the grant. These papers and reports are listed below:

  7. Biomedical imaging and sensing using flatbed scanners.

    PubMed

    Göröcs, Zoltán; Ozcan, Aydogan

    2014-09-07

    In this Review, we provide an overview of flatbed scanner based biomedical imaging and sensing techniques. The extremely large imaging field-of-view (e.g., ~600-700 cm(2)) of these devices coupled with their cost-effectiveness provide unique opportunities for digital imaging of samples that are too large for regular optical microscopes, and for collection of large amounts of statistical data in various automated imaging or sensing tasks. Here we give a short introduction to the basic features of flatbed scanners also highlighting the key parameters for designing scientific experiments using these devices, followed by a discussion of some of the significant examples, where scanner-based systems were constructed to conduct various biomedical imaging and/or sensing experiments. Along with mobile phones and other emerging consumer electronics devices, flatbed scanners and their use in advanced imaging and sensing experiments might help us transform current practices of medicine, engineering and sciences through democratization of measurement science and empowerment of citizen scientists, science educators and researchers in resource limited settings.

  8. Miniature 'Wearable' PET Scanner Ready for Use

    SciTech Connect

    Paul Vaska

    2011-03-09

    Scientists from BNL, Stony Brook University, and collaborators have demonstrated the efficacy of a "wearable," portable PET scanner they've developed for rats. The device will give neuroscientists a new tool for simultaneously studying brain function and behavior in fully awake, moving animals.

  9. Wire scanner software and firmware issues

    SciTech Connect

    Gilpatrick, John Doug

    2008-01-01

    The Los Alamos Neutron Science Center facility presently has 110 slow wire scanning profile measurement instruments located along its various beam lines. These wire scanners were developed and have been operating for at least 30 years. While the wire scanners solved many problems to operate and have served the facility well they have increasingly suffered from several problems or limitations, such as maintenance and reliability problems, antiquated components, slow data acquisition, and etc. In order to refurbish these devices, these wire scanners will be replaced with newer versions. The replacement will consist of a completely new beam line actuator, new cables, new electronics and brand new software and firmware. This note describes the functions and modes of operation that LabVIEW VI software on the real time controller and FPGA LabVIEW firmware will be required. It will be especially interesting to understand the overall architecture of these LabVIEW VIs. While this note will endeavor to describe all of the requirements and issues for the wire scanners, undoubtedly, there will be missing details that will be added as time progresses.

  10. Rail profile control using laser triangulation scanners

    NASA Astrophysics Data System (ADS)

    Boronahin, Ð. ńlexandr M.; Larionov, Daniil Yu.; Podgornaya, Liudmila N.; Shalymov, Roman V.; Filatov, Yuri V.; Bokhman, Evgueny D.

    2016-11-01

    Rail track geometric parameters measurement requires knowledge of left and right rail head location in each section. First of all displacement in transverse plane of rail head point located at a distance of 14 mm below the running surface, must be controlled [1]. It is carried out by detecting of each rail profile using triangulation laser scanners. Optical image recognition is carried out successfully in the laboratory, approaches used for this purpose are widely known. However, laser scanners operation has several features on railways leading to necessity of traditional approaches adaptation for solving these particular problems. The most significant problem is images noisiness due to the solar flashes and the effect of "Moon path" on the smooth rail surface. Using of optical filters gives inadequate result, because scanner laser diodes radiation frequency varies with temperature changes that forbid the use of narrow-band filters. Consideration of these features requires additional constructive and algorithmic solutions, including involvement of information from other sensors of the system. The specific usage of optical scanners for rail profiles control is the subject of the paper.

  11. Dedicated PET scanners for breast imaging.

    PubMed

    Freifelder, R; Karp, J S

    1997-12-01

    We have used computer simulations to compare two designs for a PET scanner dedicated to breast imaging with a whole-body PET scanner. The new designs combine high spatial resolution, high sensitivity, and good energy resolution to detect small, low-contrast masses. The detectors are position sensitive NaI(Tl) scintillators. The first design is a ring scanner surrounding the breast and the second consists of two planar detectors placed on opposite sides of the breast. We have employed standard performance measures to compare the different designs: contrast, percentage standard deviation of the background, and signal-to-noise ratios of reconstructed images. The results of the simulations show that both of the proposed designs have better lesion detectability than a whole-body scanner. The results also show that contrast is higher in the ring breast system but that the noise is lower in the planar breast system. Overall, the ring system yields images with the best signal-to-noise ratios, although the planar system offers practical advantages for imaging the breast and axilla.

  12. Dedicated PET scanners for breast imaging

    NASA Astrophysics Data System (ADS)

    Freifelder, Richard; Karp, Joel S.

    1997-12-01

    We have used computer simulations to compare two designs for a PET scanner dedicated to breast imaging with a whole-body PET scanner. The new designs combine high spatial resolution, high sensitivity, and good energy resolution to detect small, low-contrast masses. The detectors are position sensitive NaI(Tl) scintillators. The first design is a ring scanner surrounding the breast and the second consists of two planar detectors placed on opposite sides of the breast. We have employed standard performance measures to compare the different designs: contrast, percentage standard deviation of the background, and signal-to-noise ratios of reconstructed images. The results of the simulations show that both of the proposed designs have better lesion detectability than a whole-body scanner. The results also show that contrast is higher in the ring breast system but that the noise is lower in the planar breast system. Overall, the ring system yields images with the best signal-to-noise ratios, although the planar system offers practical advantages for imaging the breast and axilla.

  13. Precision Digital Position Encoding For Resonant Scanners

    NASA Astrophysics Data System (ADS)

    Reich, Stanley; Tuchman, Israel

    1984-11-01

    Presented is a versatile precision digital encoding technique for mechanical resonant scanners. Described is it's application to electronic correction of the sinusoidal scan pattern traced. To contrast the flexibility of the electronic encoding technique a number of direct correction methods are described.

  14. Learning and Teaching with a Computer Scanner

    ERIC Educational Resources Information Center

    Planinsic, G.; Gregorcic, B.; Etkina, E.

    2014-01-01

    This paper introduces the readers to simple inquiry-based activities (experiments with supporting questions) that one can do with a computer scanner to help students learn and apply the concepts of relative motion in 1 and 2D, vibrational motion and the Doppler effect. We also show how to use these activities to help students think like…

  15. Bottled liquid explosive scanner by near infrared

    NASA Astrophysics Data System (ADS)

    Itozaki, Hideo

    2016-05-01

    A bottled liquid explosive scanner has been developed using near infrared technology for glass or PET bottles and ultrasound technology for metal cans. It has database of near infrared absorbance spectra and sound velocities of various liquids. Scanned liquids can be identified by using this database. This device has been certified by ECAC and installed at Japanese international airport.

  16. Learning and Teaching with a Computer Scanner

    ERIC Educational Resources Information Center

    Planinsic, G.; Gregorcic, B.; Etkina, E.

    2014-01-01

    This paper introduces the readers to simple inquiry-based activities (experiments with supporting questions) that one can do with a computer scanner to help students learn and apply the concepts of relative motion in 1 and 2D, vibrational motion and the Doppler effect. We also show how to use these activities to help students think like…

  17. Semantic divergence and creative story generation: an fMRI investigation.

    PubMed

    Howard-Jones, Paul A; Blakemore, Sarah-Jayne; Samuel, Elspeth A; Summers, Ian R; Claxton, Guy

    2005-09-01

    The aim of this fMRI investigation was to identify those areas of the brain associated with approaching a story generation task creatively and to investigate the effects upon these correlates of incorporating a set of words that were unrelated to each other-a strategy considered to encourage semantic divergence. Preliminary experiments were undertaken to investigate the possible confounding effects of the scanner environment upon creativity and to reveal the effects of creative effort and word relatedness upon the creativity of those who would be participating in the fMRI scan. In the final part of the investigation, a factorial fMRI design was used to elucidate brain regions involved in increased creative effort and also the effect upon activity in these regions when participants incorporated words that bore little semantic relationship with each other. Results support the notion that areas of the right prefrontal cortex are critical to the types of divergent semantic processing involved with creativity in this context.

  18. Navigation of a telepresence robot via covert visuospatial attention and real-time fMRI.

    PubMed

    Andersson, Patrik; Pluim, Josien P W; Viergever, Max A; Ramsey, Nick F

    2013-01-01

    Brain-computer interfaces (BCIs) allow people with severe neurological impairment and without ability to control their muscles to regain some control over their environment. The BCI user performs a mental task to regulate brain activity, which is measured and translated into commands controlling some external device. We here show that healthy participants are capable of navigating a robot by covertly shifting their visuospatial attention. Covert Visuospatial Attention (COVISA) constitutes a very intuitive brain function for spatial navigation and does not depend on presented stimuli or on eye movements. Our robot is equipped with motors and a camera that sends visual feedback to the user who can navigate it from a remote location. We used an ultrahigh field MRI scanner (7 Tesla) to obtain fMRI signals that were decoded in real time using a support vector machine. Four healthy subjects with virtually no training succeeded in navigating the robot to at least three of four target locations. Our results thus show that with COVISA BCI, realtime robot navigation can be achieved. Since the magnitude of the fMRI signal has been shown to correlate well with the magnitude of spectral power changes in the gamma frequency band in signals measured by intracranial electrodes, the COVISA concept may in future translate to intracranial application in severely paralyzed people.

  19. Simultaneous MRI and PET imaging of a rat brain

    NASA Astrophysics Data System (ADS)

    Raylman, Raymond R.; Majewski, Stan; Lemieux, Susan K.; Sendhil Velan, S.; Kross, Brian; Popov, Vladimir; Smith, Mark F.; Weisenberger, Andrew G.; Zorn, Carl; Marano, Gary D.

    2006-12-01

    Multi-modality imaging is rapidly becoming a valuable tool in the diagnosis of disease and in the development of new drugs. Functional images produced with PET fused with anatomical structure images created by MRI will allow the correlation of form with function. Our group is developing a system to acquire MRI and PET images contemporaneously. The prototype device consists of two opposed detector heads, operating in coincidence mode. Each MRI-PET detector module consists of an array of LSO detector elements coupled through a long fibre optic light guide to a single Hamamatsu flat panel position-sensitive photomultiplier tube (PSPMT). The use of light guides allows the PSPMTs to be positioned outside the bore of a 3T MRI scanner where the magnetic field is relatively small. To test the device, simultaneous MRI and PET images of the brain of a male Sprague Dawley rat injected with FDG were successfully obtained. The images revealed no noticeable artefacts in either image set. Future work includes the construction of a full ring PET scanner, improved light guides and construction of a specialized MRI coil to permit higher quality MRI imaging.

  20. People counting and re-identification using fusion of video camera and laser scanner

    NASA Astrophysics Data System (ADS)

    Ling, Bo; Olivera, Santiago; Wagley, Raj

    2016-05-01

    We present a system for people counting and re-identification. It can be used by transit and homeland security agencies. Under FTA SBIR program, we have developed a preliminary system for transit passenger counting and re-identification using a laser scanner and video camera. The laser scanner is used to identify the locations of passenger's head and shoulder in an image, a challenging task in crowed environment. It can also estimate the passenger height without prior calibration. Various color models have been applied to form color signatures. Finally, using a statistical fusion and classification scheme, passengers are counted and re-identified.

  1. 22. SITE BUILDING 002 SCANNER BUILDING RADAR CONTROL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    22. SITE BUILDING 002 - SCANNER BUILDING - RADAR CONTROL ROOM. RECEIVER EQUIPMENT ON RIGHT WITH RF RADIATION MONITOR CABINET. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  2. 13. SITE BUILDING 002 SCANNER BUILDING "B" FACE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    13. SITE BUILDING 002 - SCANNER BUILDING - "B" FACE LOADING DOCK AND PERSONNEL ACCESS RAMP TO FALLOUT SHELTER. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  3. 28. SITE BUILDING 002 SCANNER BUILDING AT INTERIOR ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    28. SITE BUILDING 002 - SCANNER BUILDING - AT INTERIOR OF LEVEL 5, FACE A - SHOWS ANTENNA RECEIVERS, EMITTERS/RECEIVERS, IN GENERAL ARRANGEMENT. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  4. 32. SITE BUILDING 002 SCANNER BUILDING MECHANICAL ROOM ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    32. SITE BUILDING 002 - SCANNER BUILDING - MECHANICAL ROOM 105, VIEW OF OPERATIONAL SCHEMATIC OF COOLING SYSTEM LOOPS. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  5. 3. SITE BUILDING 002 SCANNER BUILDING VIEW IS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. SITE BUILDING 002 - SCANNER BUILDING - VIEW IS LOOKING NORTH 30° WEST AT "A" FACE. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  6. 1. SITE BUILDING 022 SCANNER BUILDING VIEW IS LOOKING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    1. SITE BUILDING 022- SCANNER BUILDING - VIEW IS LOOKING NORTH 70°WEST AT "B" AND "A" FACES. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  7. 4. SITE BUILDING 002 SCANNER BUILDING SOUTH 30° ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. SITE BUILDING 002 - SCANNER BUILDING - SOUTH 30° WEST - VIEW IS LOOKING AT "B" FACE. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  8. 23. SITE BUILDING 002 SCANNER BUILDING RADAR CONTROL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    23. SITE BUILDING 002 - SCANNER BUILDING - RADAR CONTROL INTERFACE "RCL NO. 2" WITH COMPUTER CONTROL DISC DRIVE UNITS IN FOREGROUND. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  9. 31. SITE BUILDING 002 SCANNER BUILDING AT INTERIOR ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    31. SITE BUILDING 002 - SCANNER BUILDING AT INTERIOR - BACK OF POWER SUPPLY UNITS 3045-17 AND 3046-29. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  10. 24. SITE BUILDING 002 SCANNER BUILDING OPERATIONS CENTER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    24. SITE BUILDING 002 - SCANNER BUILDING - OPERATIONS CENTER -- MWOC IN OPEARATION AT 1924 ZULU TIME. 26 OCTOBER, 1999. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  11. 11. SITE BUILDING 002 SCANNER BUILDING EVAPORATIVE COOLING ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    11. SITE BUILDING 002 - SCANNER BUILDING - EVAPORATIVE COOLING TOWER SYSTEM IN FOREGROUND. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  12. 18. SITE BUILDING 002 SCANNER BUILDING VIEW OF ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    18. SITE BUILDING 002 - SCANNER BUILDING - VIEW OF SITE SECURITY OFFICE ACCESS DOOR FROM EXTERIOR OF OFFICE. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  13. 33. SITE BUILDING 002 SCANNER BUILDING MECHANICAL ROOM ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    33. SITE BUILDING 002 - SCANNER BUILDING - MECHANICAL ROOM 105, VIEW OF CHILLER ROOM MOTOR CONTROL CENTER. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  14. 2. SITE BUILDING 002 SCANNER BUILDING VIEW IS ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    2. SITE BUILDING 002 - SCANNER BUILDING - VIEW IS LOOKING NORTH 80° WEST "B" FACE ALONG BUILDING "A" FACE. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  15. Occurrence and characteristics of mutual interference between LIDAR scanners

    NASA Astrophysics Data System (ADS)

    Kim, Gunzung; Eom, Jeongsook; Park, Seonghyeon; Park, Yongwan

    2015-05-01

    The LIDAR scanner is at the heart of object detection of the self-driving car. Mutual interference between LIDAR scanners has not been regarded as a problem because the percentage of vehicles equipped with LIDAR scanners was very rare. With the growing number of autonomous vehicle equipped with LIDAR scanner operated close to each other at the same time, the LIDAR scanner may receive laser pulses from other LIDAR scanners. In this paper, three types of experiments and their results are shown, according to the arrangement of two LIDAR scanners. We will show the probability that any LIDAR scanner will interfere mutually by considering spatial and temporal overlaps. It will present some typical mutual interference scenario and report an analysis of the interference mechanism.

  16. Chest MRI

    MedlinePlus

    ... as the contrast dye is injected. The MRI machine is a large, tunnel-like machine that has a table. You will lie still ... table, and the table will slide into the machine. You will hear loud humming, tapping, and buzzing ...

  17. Cardiac MRI

    MedlinePlus

    ... as the contrast dye is injected. The MRI machine is a large, tunnel-like machine that has a table. You will lie still ... table and the table will slide into the machine. You will hear loud humming, tapping, and buzzing ...

  18. The PRESTO technique for fMRI

    PubMed Central

    van Gelderen, P.; Duyn, J.H.; Ramsey, N.F.; Liu, G.; Moonen, C.T.W.

    2012-01-01

    In the early days of BOLD fMRI, the acquisition of T2* weighted data was greatly facilitated by rapid scan techniques such as EPI. The latter, however, was only available on a few MRI systems that were equipped with specialized hardware that allowed rapid switching of the imaging gradients. For this reason, soon after the invention of fMRI, the scan technique PRESTO was developed to make rapid T2* weighted scanning available on standard clinical scanning. This method combined echo shifting, which allows for echo times longer than the sequence repetition time, with acquisition of multiple k-space lines per excitation. These two concepts were combined in order to achieve a method fast enough for fMRI, while maintaining a sufficiently long echo time for optimal contrast. PRESTO has been primarily used for 3D scanning, which minimized the contribution of large vessels due to inflow effects. Although PRESTO is still being used today, its appeal has lessened somewhat due to increased gradient performance of modern MRI scanners. Compared to 2D EPI, PRESTO may have somewhat reduced temporal stability, which is a disadvantage for fMRI that may not outweigh the advantage of reduced inflow effects provided by 3D scanning. In this overview, the history of the development of the PRESTO is presented, followed by a qualitative comparison with EPI. PMID:22245350

  19. Diffusion MRI and its Role in Neuropsychology.

    PubMed

    Mueller, Bryon A; Lim, Kelvin O; Hemmy, Laura; Camchong, Jazmin

    2015-09-01

    Diffusion Magnetic Resonance Imaging (dMRI) is a popular method used by neuroscientists to uncover unique information about the structural connections within the brain. dMRI is a non-invasive imaging methodology in which image contrast is based on the diffusion of water molecules in tissue. While applicable to many tissues in the body, this review focuses exclusively on the use of dMRI to examine white matter in the brain. In this review, we begin with a definition of diffusion and how diffusion is measured with MRI. Next we introduce the diffusion tensor model, the predominant model used in dMRI. We then describe acquisition issues related to acquisition parameters and scanner hardware and software. Sources of artifacts are then discussed, followed by a brief review of analysis approaches. We provide an overview of the limitations of the traditional diffusion tensor model, and highlight several more sophisticated non-tensor models that better describe the complex architecture of the brain's white matter. We then touch on reliability and validity issues of diffusion measurements. Finally, we describe examples of ways in which dMRI has been applied to studies of brain disorders and how identified alterations relate to symptomatology and cognition.

  20. Diffusion MRI and its role in neuropsychology

    PubMed Central

    Mueller, Bryon A; Lim, Kelvin O; Hemmy, Laura; Camchong, Jazmin

    2015-01-01

    Diffusion Magnetic Resonance Imaging (dMRI) is a popular method used by neuroscientists to uncover unique information about the structural connections within the brain. dMRI is a non-invasive imaging methodology in which image contrast is based on the diffusion of water molecules in tissue. While applicable to many tissues in the body, this review focuses exclusively on the use of dMRI to examine white matter in the brain. In this review, we begin with a definition of diffusion and how diffusion is measured with MRI. Next we introduce the diffusion tensor model, the predominant model used in dMRI. We then describe acquisition issues related to acquisition parameters and scanner hardware and software. Sources of artifacts are then discussed, followed by a brief review of analysis approaches. We provide an overview of the limitations of the traditional diffusion tensor model, and highlight several more sophisticated non-tensor models that better describe the complex architecture of the brain’s white matter. We then touch on reliability and validity issues of diffusion measurements. Finally, we describe examples of ways in which dMRI has been applied to studies of brain disorders and how identified alterations relate to symptomatology and cognition. PMID:26255305

  1. Management of a sandbag accident in an MRI unit.

    PubMed

    Lee, Chee Hwee; Lin, Ming-Fang; Chan, Wing P

    2015-11-01

    Our aim is to report the cause and management of a ferromagnetic sandbag accident that occurred when an unconscious patient was sent for brain MRI. A 2-kg sandbag had been placed in the vicinity of his right groin to aid hemostasis after a femoral venous puncture for thrombocytopenia. His clothing and blanket had not been examined thoroughly before he was moved to the scanner and the sandbag went unnoticed. Its attraction to the scanner and adherence to the scanner rim resulted in a minor abrasion and bruise on the patient's face. We decided to manually remove some of the pellets from the sandbag after cutting the vinyl bag at one corner with a nonferromagnetic screwdriver. Piece-meal removal of about two-thirds of the pellets facilitated removal of the remaining pellets and the sandbag as a whole. The word "sandbag" is misleading and led to a lack of communication between the clinical team and the MRI staff and failure by the MRI staff to recognize a sandbag as a ferromagnetic object. Careful manual removal of small amounts of pellets can be used to avoid more time- and labor-intensive strategies to deal with a sandbag accident (e.g., magnet quench or ramp-down). Installation of a ferromagnetic material detector to screen patients before entering the scanner room is recommended.

  2. A Novel MRI Marker for Prostate Brachytherapy

    SciTech Connect

    Frank, Steven J. Stafford, R. Jason; Bankson, James A.; Li Chun; Swanson, David A.; Kudchadker, Rajat J.; Martirosyan, Karen S.

    2008-05-01

    Purpose: Magnetic resonance imaging (MRI) is the optimal imaging modality for the prostate and surrounding critical organ structures. However, on MRI, the titanium radioactive seeds used for brachytherapy appear as black holes (negative contrast) and cannot be accurately localized. We sought to develop an encapsulated contrast agent marker (ECAM) with high-signal intensity on MRI to permit accurate localization of radioactive seeds with MRI during and after prostate brachytherapy. Methods and Materials: We investigated several agents with paramagnetic and superparamagnetic properties. The agents were injected into titanium, acrylic, and glass seeds, which were linked together in various combinations and imaged with MRI. The agent with the greatest T1-weighted signal was tested further in a canine prostate and agarose phantom. Studies were performed on a 1.5-T clinical MRI scanner. Results: The cobalt-chloride complex contrast (C4) agent with stoichiometry (CoCl{sub 2}){sub 0.8}(C{sub 2}H{sub 5}NO{sub 2}){sub 0.2} had the greatest T1-weighted signal (positive contrast) with a relaxivity ratio >1 (r{sub 2}/r{sub 1} = 1.21 {+-} 0.29). Acrylic-titanium and glass-titanium seed strands were clearly visualized with the encapsulated contrast agent marker. Conclusion: We have developed a novel ECAM that permits positive identification of the radioactive seeds used for prostate brachytherapy on MRI. Preclinical in vitro phantom studies and in vivo canine studies are needed to further optimize MRI sequencing techniques to facilitate MRI-based dosimetry.

  3. 21 CFR 892.1300 - Nuclear rectilinear scanner.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Nuclear rectilinear scanner. 892.1300 Section 892...) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1300 Nuclear rectilinear scanner. (a) Identification. A nuclear rectilinear scanner is a device intended to image the distribution of radionuclides...

  4. 21 CFR 892.1330 - Nuclear whole body scanner.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Nuclear whole body scanner. 892.1330 Section 892...) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1330 Nuclear whole body scanner. (a) Identification. A nuclear whole body scanner is a device intended to measure and image the distribution...

  5. 21 CFR 882.1925 - Ultrasonic scanner calibration test block.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Ultrasonic scanner calibration test block. 882... Ultrasonic scanner calibration test block. (a) Identification. An ultrasonic scanner calibration test block is a block of material with known properties used to calibrate ultrasonic scanning devices (e.g.,...

  6. 21 CFR 882.1925 - Ultrasonic scanner calibration test block.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Ultrasonic scanner calibration test block. 882... Ultrasonic scanner calibration test block. (a) Identification. An ultrasonic scanner calibration test block is a block of material with known properties used to calibrate ultrasonic scanning devices (e.g.,...

  7. Applications of Optical Scanners in an Academic Center.

    ERIC Educational Resources Information Center

    Molinari, Carol; Tannenbaum, Robert S.

    1995-01-01

    Describes optical scanners, including how the technology works; applications in data management and research; development of instructional materials; and providing community services. Discussion includes the three basic types of optical scanners: optical character recognition (OCR), optical mark readers (OMR), and graphic scanners. A sidebar…

  8. MAPS – a Magic Angle Positioning System for Enhanced Imaging in High-Field Small-Bore MRI

    PubMed Central

    Squires, Alexander; Chan, Kevin C.; Ho, Leon C.; Sigal, Ian A.; Jan, Ning-Jiun

    2016-01-01

    The “magic angle” MRI effect can enhance signal intensity in aligned collagenous structures oriented at approximately 55° with respect to the main magnetic field. The difficulty of positioning tissue inside closed-bore scanners has hampered magic angle use in research and clinics. An MRI-conditional mechatronic system has been developed to control sample orientation inside a 9.4T small bore MRI scanner. The system orients samples to within 0.5° and enables a 600% increase in tendon signal intensity. PMID:28713864

  9. MAPS - a Magic Angle Positioning System for Enhanced Imaging in High-Field Small-Bore MRI.

    PubMed

    Squires, Alexander; Chan, Kevin C; Ho, Leon C; Sigal, Ian A; Jan, Ning-Jiun; Tse, Zion Tsz Ho

    2016-03-01

    The "magic angle" MRI effect can enhance signal intensity in aligned collagenous structures oriented at approximately 55° with respect to the main magnetic field. The difficulty of positioning tissue inside closed-bore scanners has hampered magic angle use in research and clinics. An MRI-conditional mechatronic system has been developed to control sample orientation inside a 9.4T small bore MRI scanner. The system orients samples to within 0.5° and enables a 600% increase in tendon signal intensity.

  10. MRI Stealth” robot for prostate interventions

    PubMed Central

    STOIANOVICI, DAN; SONG, DANNY; PETRISOR, DORU; URSU, DANIEL; MAZILU, DUMITRU; MUTENER, MICHAEL; SCHAR, MICHAEL; PATRICIU, ALEXANDRU

    2011-01-01

    The paper reports an important achievement in MRI instrumentation, a pneumatic, fully actuated robot located within the scanner alongside the patient and operating under remote control based on the images. Previous MRI robots commonly used piezoelectric actuation limiting their compatibility. Pneumatics is an ideal choice for MRI compatibility because it is decoupled from electromagnetism, but pneumatic actuators were hardly controllable. This achievement was possible due to a recent technology breakthrough, the invention of a new type of pneumatic motor, PneuStep (1), designed for the robot reported here with uncompromised MRI compatibility, high-precision, and medical safety. MrBot is one of the “MRI stealth” robots today (the second is described in this issue by Zangos et al.). Both of these systems are also multi-imager compatible, being able to operate with the imager of choice or cross-imaging modalities. For MRI compatibility the robot is exclusively constructed of nonmagnetic and dielectric materials such as plastics, ceramics, crystals, rubbers and is electricity free. Light-based encoding is used for feedback, so that all electric components are distally located outside the imager’s room. MRI robots are modern, digital medical instruments in line with advanced imaging equipment and methods. These allow for accessing patients within closed bore scanners and performing interventions under direct (in scanner) imaging feedback. MRI robots could allow e.g. to biopsy small lesions imaged with cutting edge cancer imaging methods, or precisely deploy localized therapy at cancer foci. Our robot is the first to show the feasibility of fully automated in-scanner interventions. It is customized for the prostate and operates transperineally for needle interventions. It can accommodate various needle drivers for different percutaneous procedures such as biopsy, thermal ablations, or brachytherapy. The first needle driver is customized for fully automated low

  11. Optimized magnetic resonance diffusion protocol for ex-vivo whole human brain imaging with a clinical scanner

    NASA Astrophysics Data System (ADS)

    Scherrer, Benoit; Afacan, Onur; Stamm, Aymeric; Singh, Jolene; Warfield, Simon K.

    2015-03-01

    Diffusion-weighted magnetic resonance imaging (DW-MRI) provides a novel insight into the brain to facilitate our understanding of the brain connectivity and microstructure. While in-vivo DW-MRI enables imaging of living patients and longitudinal studies of brain changes, post-mortem ex-vivo DW-MRI has numerous advantages. Ex-vivo imaging benefits from greater resolution and sensitivity due to the lack of imaging time constraints; the use of tighter fitting coils; and the lack of movement artifacts. This allows characterization of normal and abnormal tissues with unprecedented resolution and sensitivity, facilitating our ability to investigate anatomical structures that are inaccessible in-vivo. This also offers the opportunity to develop today novel imaging biomarkers that will, with tomorrow's MR technology, enable improved in-vivo assessment of the risk of disease in an individual. Post-mortem studies, however, generally rely on the fixation of specimen to inhibit tissue decay which starts as soon as tissue is deprived from its blood supply. Unfortunately, fixation of tissues substantially alters tissue diffusivity profiles. In addition, ex-vivo DW-MRI requires particular care when packaging the specimen because the presence of microscopic air bubbles gives rise to geometric and intensity image distortion. In this work, we considered the specific requirements of post-mortem imaging and designed an optimized protocol for ex-vivo whole brain DW-MRI using a human clinical 3T scanner. Human clinical 3T scanners are available to a large number of researchers and, unlike most animal scanners, have a bore diameter large enough to image a whole human brain. Our optimized protocol will facilitate widespread ex-vivo investigations of large specimen.

  12. Compact conscious animal positron emission tomography scanner

    DOEpatents

    Schyler, David J.; O'Connor, Paul; Woody, Craig; Junnarkar, Sachin Shrirang; Radeka, Veljko; Vaska, Paul; Pratte, Jean-Francois; Volkow, Nora

    2006-10-24

    A method of serially transferring annihilation information in a compact positron emission tomography (PET) scanner includes generating a time signal for an event, generating an address signal representing a detecting channel, generating a detector channel signal including the time and address signals, and generating a composite signal including the channel signal and similarly generated signals. The composite signal includes events from detectors in a block and is serially output. An apparatus that serially transfers annihilation information from a block includes time signal generators for detectors in a block and an address and channel signal generator. The PET scanner includes a ring tomograph that mounts onto a portion of an animal, which includes opposing block pairs. Each of the blocks in a block pair includes a scintillator layer, detection array, front-end array, and a serial encoder. The serial encoder includes time signal generators and an address signal and channel signal generator.

  13. Ghost signals in Allison emittance scanners

    SciTech Connect

    Stockli, Martin P.; Leitner, M.; Moehs, D.P.; Keller, R.; Welton, R.F.; /SNS Project, Oak Ridge /Tennessee U.

    2004-12-01

    For over 20 years, Allison scanners have been used to measure emittances of low-energy ion beams. We show that scanning large trajectory angles produces ghost signals caused by the sampled beamlet impacting on an electric deflection plate. The ghost signal strength is proportional to the amount of beam entering the scanner. Depending on the ions, and their velocity, the ghost signals can have the opposite or the same polarity as the main beam signals. The ghost signals cause significant errors in the emittance estimates because they appear at large trajectory angles. These ghost signals often go undetected because they partly overlap with the real signals, are mostly below the 1% level, and often hide in the noise. A simple deflection plate modification is shown to reduce the ghost signal strength by over 99%.

  14. Electrothermal MEMS fiber scanner for optical endomicroscopy.

    PubMed

    Seo, Yeong-Hyeon; Hwang, Kyungmin; Park, Hyeon-Cheol; Jeong, Ki-Hun

    2016-02-22

    We report a novel MEMS fiber scanner with an electrothermal silicon microactuator and a directly mounted optical fiber. The microactuator comprises double hot arm and cold arm structures with a linking bridge and an optical fiber is aligned along a silicon fiber groove. The unique feature induces separation of resonant scanning frequencies of a single optical fiber in lateral and vertical directions, which realizes Lissajous scanning during the resonant motion. The footprint dimension of microactuator is 1.28 x 7 x 0.44 mm3. The resonant scanning frequencies of a 20 mm long optical fiber are 239.4 Hz and 218.4 Hz in lateral and vertical directions, respectively. The full scanned area indicates 451 μm x 558 μm under a 16 Vpp pulse train. This novel laser scanner can provide many opportunities for laser scanning endomicroscopic applications.

  15. The Galileo star scanner observations at Amalthea

    NASA Astrophysics Data System (ADS)

    Fieseler, Paul D.; Adams, Olen W.; Vandermey, Nancy; Theilig, E. E.; Schimmels, Kathryn A.; Lewis, George D.; Ardalan, Shadan M.; Alexander, Claudia J.

    2004-06-01

    In November of 2002, the Galileo spacecraft passed within 250 km of Jupiter's moon Amalthea. An onboard telescope, the star scanner, observed a series of bright flashes near the moon. It is believed that these flashes represent sunlight reflected from 7 to 9 small moonlets located within about 3000 km of Amalthea. From star scanner geometry considerations and other arguments, we can constrain the diameter of the observed bodies to be between 0.5 m to several tens of kilometers. In September of 2003, while crossing Amalthea's orbit just prior to Galileo's destruction in the jovian atmosphere, a single additional body seems to have been observed. It is suspected that these bodies are part of a discrete rocky ring embedded within Jupiter's Gossamer ring system.

  16. Scanners for analytic print measurement: the devil in the details

    NASA Astrophysics Data System (ADS)

    Zeise, Eric K.; Williams, Don; Burns, Peter D.; Kress, William C.

    2007-01-01

    Inexpensive and easy-to-use linear and area-array scanners have frequently substituted as colorimeters and densitometers for low-frequency (i.e., large area) hard copy image measurement. Increasingly, scanners are also being used for high spatial frequency, image microstructure measurements, which were previously reserved for high performance microdensitometers. In this paper we address characteristics of flatbed reflection scanners in the evaluation of print uniformity, geometric distortion, geometric repeatability and the influence of scanner MTF and noise on analytic measurements. Suggestions are made for the specification and evaluation of scanners to be used in print image quality standards that are being developed.

  17. A compact vertical scanner for atomic force microscopes.

    PubMed

    Park, Jae Hong; Shim, Jaesool; Lee, Dong-Yeon

    2010-01-01

    A compact vertical scanner for an atomic force microscope (AFM) is developed. The vertical scanner is designed to have no interference with the optical microscope for viewing the cantilever. The theoretical stiffness and resonance of the scanner are derived and verified via finite element analysis. An optimal design process that maximizes the resonance frequency is performed. To evaluate the scanner's performance, experiments are performed to evaluate the travel range, resonance frequency, and feedback noise level. In addition, an AFM image using the proposed vertical scanner is generated.

  18. Ground location of satellite scanner data

    NASA Technical Reports Server (NTRS)

    Puccinelli, E. F.

    1976-01-01

    This paper presents simple and accurate mathematical formulation for determining the ground location of remote sensor data. The techniques used are based on elementary concepts of differential geometry and lead to the development of a relation that gives location as a function of surface ellipticity, satellite position, velocity, attitude, and scanner orientation. The formula lends itself to simply computer coding and will hopefully lead to a standardization of the various techniques which have been developed to solve this problem.

  19. Point Relay Scanner Utilizing Ellipsoidal Mirrors

    NASA Technical Reports Server (NTRS)

    Manhart, Paul K. (Inventor); Pagano, Robert J. (Inventor)

    1997-01-01

    A scanning system uses a polygonal mirror assembly with each facet of the polygon having an ellipsoidal mirror located thereon. One focal point of each ellipsoidal mirror is located at a common point on the axis of rotation of the polygonal mirror assembly. As the mirror assembly rotates. a second focal point of the ellipsoidal mirrors traces out a scan line. The scanner can be utilized for scanned output display of information or for scanning information to be detected.

  20. Learning and teaching with a computer scanner

    NASA Astrophysics Data System (ADS)

    Planinsic, G.; Gregorcic, B.; Etkina, E.

    2014-09-01

    This paper introduces the readers to simple inquiry-based activities (experiments with supporting questions) that one can do with a computer scanner to help students learn and apply the concepts of relative motion in 1 and 2D, vibrational motion and the Doppler effect. We also show how to use these activities to help students think like scientists. They will conduct simple experiments, construct different explanations for their observations, test their explanations in new experiments and represent their ideas in multiple ways.

  1. Reliability evaluation of a MEMS scanner

    NASA Astrophysics Data System (ADS)

    Lani, S.; Marozau, Y.; Dadras, M.

    2017-02-01

    Previously, the realization and closed loop control of a MEMS scanner integrating position sensors made with piezoresistive sensors was presented. It consisted of a silicon compliant membrane with integrated position sensors, on which a mirror and a magnet were assembled. This device was mounted on a PCB containing coils for electromagnetic actuation. In this work, the reliability of such system was evaluated through thermal and mechanical analysis. The objective of thermal analysis was to evaluate the lifetime of the MEMS scanner and is consisting of temperature cycling (-40°C to 100°C) and accelerated electrical endurance (100°C with power supplied to all electrical components). The objective of mechanical analysis was to assess the resistance of the system to mechanical stress and is consisting of mechanical shock and vibration. A high speed camera has been used to observe the behavior of the MEMS scanner. The use of shock stopper to improve the mechanical resistance has been evaluated and had demonstrated a resistance increase from 250g to 900g. The minimum shock resistance required for the system is 500g for transportation and 1000g for portative devices.

  2. Techniques for Fast Stereoscopic MRI

    PubMed Central

    Guttman, Michael A.; McVeigh, Elliot R.

    2007-01-01

    Stereoscopic MRI can impart 3D perception with only two image acquisitions. This economy over standard multiplanar 3D volume renderings allows faster frame rates, which are needed for real-time imaging applications. Real-time 3D perception may enhance the appreciation of complex anatomical structures, and may improve hand-eye coordination while manipulating a medical device during an image-guided interventional procedure. To this goal, a system is being developed to acquire and display stereoscopic MR images in real-time. A clinically used, fast gradient-recalled echo-train sequence has been modified to produce stereo image pairs. Features have been added for depth cueing, view sharing, and bulk signal suppression. A workstation was attached to a clinical MR scanner for fast data extraction, image reconstruction and stereoscopic image display. PMID:11477636

  3. Battlefield MRI

    SciTech Connect

    Espy, Michelle

    2015-06-01

    Magnetic Resonance Imaging is the best method for non-invasive imaging of soft tissue anatomy, saving countless lives each year. It is regarded as the gold standard for diagnosis of mild to moderate traumatic brain injuries. Furthermore, conventional MRI relies on very high, fixed strength magnetic fields (> 1.5 T) with parts-per-million homogeneity, which requires very large and expensive magnets.

  4. Towards automatic quantitative quality control for MRI

    NASA Astrophysics Data System (ADS)

    Lauzon, Carolyn B.; Caffo, Brian C.; Landman, Bennett A.

    2012-02-01

    Quality and consistency of clinical and research data collected from Magnetic Resonance Imaging (MRI) scanners may become suspect due to a wide variety of common factors including, experimental changes, hardware degradation, hardware replacement, software updates, personnel changes, and observed imaging artifacts. Standard practice limits quality analysis to visual assessment by a researcher/clinician or a quantitative quality control based upon phantoms which may not be timely, cannot account for differing experimental protocol (e.g. gradient timings and strengths), and may not be pertinent to the data or experimental question at hand. This paper presents a parallel processing pipeline developed towards experiment specific automatic quantitative quality control of MRI data using diffusion tensor imaging (DTI) as an experimental test case. The pipeline consists of automatic identification of DTI scans run on the MRI scanner, calculation of DTI contrasts from the data, implementation of modern statistical methods (wild bootstrap and SIMEX) to assess variance and bias in DTI contrasts, and quality assessment via power calculations and normative values. For this pipeline, a DTI specific power calculation analysis is developed as well as the first incorporation of bias estimates in DTI data to improve statistical analysis.

  5. MRI: are you playing your system like a fiddle or a Stradivarius? Where we are headed and how to keep up.

    PubMed

    Carroll-Callahan, Catherine M; Andersson, Lars A

    2004-01-01

    Dr. Raymond Damadian performed the first human magnetic resonance imaging (MRI) scan in 1977. Unveiled from behind the research curtain, MRI technology was introduced to the clinical environment by the mid 1980s. Most academic and largehospitals lined up right away and purchased their first scanners as soon as they became available. The race began, and the MRI learning process at radiology departments all over the world started. As with any growing technology, came a surge of competition--manufacturers as well as imaging facilities. MRI technology flooded the medical community, since it provided enormous benefits for patients and doctors. It was like a rocket launching with scientists and original equipment manufacturers (OEMs) researching, creating and contributing to the advancement of clinical science and forever improved diagnoses. Radiologists at UCLA predict that most of today's procedures currently falling under research will flourish in the clinical setting within the next 5 years. The rise of PET technology and the ability to fuse metabolic images with an anatomical MRI map will undoubtedly prove invaluable for staging of pathology, treatment planning and tracking, especially when the disease is present within soft tissue, like the brain. Another sign that MRI is a healthy addition to medical imaging is the increasing number of MRI reimbursement codes. However, Medicare, Medicaid and private insurance companies are also scrutinizing more and paying less today than they did yesterday. There will always be certain myths about how bigger is always better. That's not to say system enhancements and advancements are not essential to medical imaging, but the needs and budgets differ for each facility. Regardless of site needs or budget, it is imperative that all facilities utilize the equipment they have to their maximum potential. The new "bells and whistles" might not be needed to stay competitive. Innovative technology continues to be available as long as

  6. Sodium MRI.

    PubMed

    Ouwerkerk, Ronald

    2011-01-01

    Sodium ((23)Na) imaging has a place somewhere between (1)H-MRI and MR spectroscopy (MRS). Like MRS it potentially provides information on metabolic processes, but only one single resonance of ionic (23)Na is observed. Therefore pulse sequences do not need to code for a chemical shift dimension, allowing (23)Na images to be obtained at high resolutions as compared to MRS. In this chapter the biological significance of sodium in the brain will be discussed, as well as methods for observing it with (23)Na-MRI. Many vital cellular processes and interactions in excitable tissues depend on the maintenance of a low intracellular and high extracellular sodium concentration. Healthy cells maintain this concentration gradient at the cost of energy. Leaky cell membranes or an impaired energy metabolism immediately leads to an increase in cytosolic total tissue sodium. This makes sodium a biomarker for ischemia, cancer, excessive tissue activation, or tissue damage as might be caused by ablation therapy. Special techniques allow quantification of tissue sodium for the monitoring of disease or therapy in longitudinal studies or preferential observation of the intracellular component of the tissue sodium. New methods and high-field magnet technology provide new opportunities for (23)Na-MRI in clinical and biomedical research.

  7. Telescope with a wide field of view internal optical scanner

    NASA Technical Reports Server (NTRS)

    Degnan, III, John James (Inventor); Zheng, Yunhui (Inventor)

    2012-01-01

    A telescope with internal scanner utilizing either a single optical wedge scanner or a dual optical wedge scanner and a controller arranged to control a synchronous rotation of the first and/or second optical wedges, the wedges constructed and arranged to scan light redirected by topological surfaces and/or volumetric scatterers. The telescope with internal scanner further incorporates a first converging optical element that receives the redirected light and transmits the redirected light to the scanner, and a second converging optical element within the light path between the first optical element and the scanner arranged to reduce an area of impact on the scanner of the beam collected by the first optical element.

  8. Integration of Diagnostic and Interventional MRI for the Study of Persistent Prostate Cancer after External Beam Radiotherapy

    DTIC Science & Technology

    2009-10-01

    Interventional MRI for the Study of Persistent Prostate Cancer after External Beam Radiotherapy PRINCIPAL INVESTIGATOR: Cynthia Ménard, M.D...2009 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Integration of Diagnostic and Interventional MRI for the Study of Persistent Prostate Cancer after...clinical testing of a novel technique for magnetic resonance imaging ( MRI ) guided prostate biopsy in a 1.5T horizontal bore scanner using a dedicated

  9. Color influence on accuracy of 3D scanners based on structured light

    NASA Astrophysics Data System (ADS)

    Voisin, Sophie; Page, David L.; Foufou, Sebti; Truchetet, Frédéric; Abidi, Mongi A.

    2006-02-01

    The characterization of commercial 3D scanners allows acquiring precise and useful data. The accuracy of range and, more recently, color for 3D scanners is usually studied separately, but when the 3D scanner is based on structured light with a color coding pattern, color influence on range accuracy should be investigated. The commercial product that we have tested has the particularity that it can acquire data under ambient light instead of a controlled environment as it is with most available scanners. Therefore, based on related work in the literature and on experiments we have done on a variety of standard illuminants, we have designed an interesting setup to control illuminant interference. Basically, the setup consists of acquiring the well-known Macbeth ColorChecker under a controlled environment and also ambient daylight. The results have shown variations with respect to the color. We have performed several statistical studies to show how the range results evolve with respect to the RGB and the HSV channels. In addition, a systematic noise error has also been identified. This noise depends on the object color. A subset of colors shows strong noise errors while other colors have minimal or even no systematic error under the same illuminant.

  10. Design of a Second Generation Firewire Based Data Acquisition System for Small Animal PET Scanners.

    PubMed

    Lewellen, T K; Miyaoka, R S; Macdonald, L R; Haselman, M; Dewitt, D; Hunter, William; Hauck, S

    2008-10-19

    The University of Washington developed a Firewire based data acquisition system for the MiCES small animal PET scanner. Development work has continued on new imaging scanners that require more data channels and need to be able to operate within a MRI imaging system. To support these scanners, we have designed a new version of our data acquisition system that leverages the capabilities of modern field programmable gate arrays (FPGA). The new design preserves the basic approach of the original system, but puts almost all functions into the FPGA, including the Firewire elements, the embedded processor, and pulse timing and pulse integration. The design has been extended to support implementation of the position estimation and DOl algorithms developed for the cMiCE detector module. The design is centered around an acquisition node board (ANB) that includes 65 ADC channels, Firewire 1394b support, the FPGA, a serial command bus and signal lines to support a rough coincidence window implementation to reject singles events from being sent on the Firewire bus. Adapter boards convert detector signals into differential paired signals to connect to the ANB.

  11. PET and MRI: The Odd Couple or a Match Made in Heaven?

    PubMed Central

    Catana, Ciprian; Guimaraes, Alexander R.; Rosen, Bruce R.

    2013-01-01

    Positron emission tomography (PET) and magnetic resonance imaging (MRI) are imaging modalities routinely used for clinical and research applications. Integrated scanners capable of acquiring PET and MRI data in the same imaging session, sequentially or simultaneously, have recently become available for human use. In this manuscript, we describe some of the technical advances that allowed the development of human PET/MR scanners, briefly discuss methodological challenges and opportunities provided by this novel technology and present potential oncologic, cardiac, and neuro-psychiatric applications. These examples range from studies that might immediately benefit from PET/MR to more advanced applications where future development might have an even broader impact. PMID:23492887

  12. Diffeomorphic Anatomical Registration Through Exponentiated Lie Algebra provides reduced effect of scanner for cortex volumetry with atlas-based method in healthy subjects.

    PubMed

    Goto, Masami; Abe, Osamu; Aoki, Shigeki; Hayashi, Naoto; Miyati, Tosiaki; Takao, Hidemasa; Iwatsubo, Takeshi; Yamashita, Fumio; Matsuda, Hiroshi; Mori, Harushi; Kunimatsu, Akira; Ino, Kenji; Yano, Keiichi; Ohtomo, Kuni

    2013-07-01

    This study aimed to investigate whether the effect of scanner for cortex volumetry with atlas-based method is reduced using Diffeomorphic Anatomical Registration Through Exponentiated Lie Algebra (DARTEL) normalization compared with standard normalization. Three-dimensional T1-weighted magnetic resonance images (3D-T1WIs) of 21 healthy subjects were obtained and evaluated for effect of scanner in cortex volumetry. 3D-T1WIs of the 21 subjects were obtained with five MRI systems. Imaging of each subject was performed on each of five different MRI scanners. We used the Voxel-Based Morphometry 8 tool implemented in Statistical Parametric Mapping 8 and WFU PickAtlas software (Talairach brain atlas theory). The following software default settings were used as bilateral region-of-interest labels: "Frontal Lobe," "Hippocampus," "Occipital Lobe," "Orbital Gyrus," "Parietal Lobe," "Putamen," and "Temporal Lobe." Effect of scanner for cortex volumetry using the atlas-based method was reduced with DARTEL normalization compared with standard normalization in Frontal Lobe, Occipital Lobe, Orbital Gyrus, Putamen, and Temporal Lobe; was the same in Hippocampus and Parietal Lobe; and showed no increase with DARTEL normalization for any region of interest (ROI). DARTEL normalization reduces the effect of scanner, which is a major problem in multicenter studies.

  13. Replication of Functional MRI Detection of Deception

    PubMed Central

    Kozel, F. Andrew; Laken, Steven J.; Johnson, Kevin A.; Boren, Bryant; Mapes, Kimberly S.; Morgan, Paul S.; George, Mark S.

    2009-01-01

    Background Several studies support the use of fMRI for detecting deception. There have been, however, no reported replications on different scanners or at different locations. In a previous study, deception was accurately detected in at least 90% of the participants in two independent cohorts. This study attempted to replicate those findings using a different scanner and location. Methods Healthy participants 18–50 years of age were recruited from the local community. After providing written informed consent, participants were screened to ensure that they were healthy, not taking any medications, and safe to have an MRI. For the testing paradigm, subjects chose one of two objects (ring or watch) to “steal” and placed it in their locker. Participants were then scanned while being visually presented with a series of questions. Functional MRI analysis was performed in the same manner as described in Kozel et al. 2005. A Chi-Squared test was used to test for a significant difference between the results in the previous study and in this replication study. Results Thirty subjects (20 women, mean age 29.0±6.5 years) were scanned with one subject being noncompliant with the protocol. Twenty-five of twenty-nine (86%) participants were correctly identified when being deceptive. There was no statistical difference between the accuracy rate obtained in this study (25/29) versus the previous study (28/31) (Chi-Squared, χ2=0.246, p=0.6197). Conclusions Our methodology for detecting deception was successfully replicated at a different site suggesting that this methodology is robust and independent of both scanner and location. PMID:19844599

  14. Exposure to MRI-related magnetic fields and vertigo in MRI workers.

    PubMed

    Schaap, Kristel; Portengen, Lützen; Kromhout, Hans

    2016-03-01

    Vertigo has been reported by people working around magnetic resonance imaging (MRI) scanners and was found to increase with increasing strength of scanner magnets. This suggests an association with exposure to static magnetic fields (SMF) and/or motion-induced time-varying magnetic fields (TVMF). This study assessed the association between various metrics of shift-long exposure to SMF and TVMF and self-reported vertigo among MRI workers. We analysed 358 shifts from 234 employees at 14 MRI facilities in the Netherlands. Participants used logbooks to report vertigo experienced during the work day at the MRI facility. In addition, personal exposure to SMF and TVMF was measured during the same shifts, using portable magnetic field dosimeters. Vertigo was reported during 22 shifts by 20 participants and was significantly associated with peak and time-weighted average (TWA) metrics of SMF as well as TVMF exposure. Associations were most evident with full-shift TWA TVMF exposure. The probability of vertigo occurrence during a work shift exceeded 5% at peak exposure levels of 409 mT and 477 mT/s and at full-shift TWA levels of 3 mT and 0.6 mT/s. These results confirm the hypothesis that vertigo is associated with exposure to MRI-related SMF and TVMF. Strong correlations between various metrics of shift-long exposure make it difficult to disentangle the effects of SMF and TVMF exposure, or identify the most relevant exposure metric. On the other hand, this also implies that several metrics of shift-long exposure to SMF and TVMF should perform similarly in epidemiological studies on MRI-related vertigo. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  15. Measuring eye states in functional MRI.

    PubMed

    Brodoehl, Stefan; Witte, Otto W; Klingner, Carsten M

    2016-07-13

    In many functional magnetic resonance imaging (fMRI) studies, experimental design often depends on the eye state (i.e., whether the participants had their eyes open or closed). Closed eyes during an fMRI is the general convention, particularly when patients are in a resting-state, but the eye state is difficult to verify. Although knowledge of the impact of the eye state on brain activity is steadily growing, only a few research groups have implemented standardized procedures to monitor eye movements and eye state. These procedures involve advanced methods that are costly (e.g., fMRI-compatible cameras) and often time-consuming (e.g., EEG/EOG). We present a simple method that distinguishes open from closed eyes utilizing functional MR images alone. The utility of this method was demonstrated on fMRI data from 14 healthy subjects who had to open and close their eyes according to a predetermined protocol (3.0 T MRI scanner, EPI sequence with 3 × 3 × 3 mm voxels, TR 2.52 s). The method presented herein is capable of extracting the movement direction of the eyes. All described methods are applicable for pre- and post-normalized MR images and are freely available through a MATLAB toolbox.

  16. Biomedical Applications of Sodium MRI In Vivo

    PubMed Central

    Madelin, Guillaume; Regatte, Ravinder R.

    2013-01-01

    In this article, we present an up-to-date overview of the potential biomedical applications of sodium MRI in vivo. Sodium MRI is a subject of increasing interest in translational imaging research as it can give some direct and quantitative biochemical information on the tissue viability, cell integrity and function, and therefore not only help the diagnosis but also the prognosis of diseases and treatment outcomes. It has already been applied in vivo in most of human tissues, such as brain for stroke or tumor detection and therapeutic response, in breast cancer, in articular cartilage, in muscle and in kidney, and it was shown in some studies that it could provide very useful new information not available through standard proton MRI. However, this technique is still very challenging due to the low detectable sodium signal in biological tissue with MRI and hardware/software limitations of the clinical scanners. The article is divided in three parts: (1) the role of sodium in biological tissues, (2) a short review on sodium magnetic resonance, and (3) a review of some studies on sodium MRI on different organs/diseases to date. PMID:23722972

  17. Design and control of a nanoprecision XYΘ scanner

    NASA Astrophysics Data System (ADS)

    Choi, Young-Man; Kim, Jung Jae; Kim, Jinwoo; Gweon, Dae-Gab

    2008-04-01

    This paper describes the design and control of a nanoprecision XYΘ scanner consisting of voice coil motors and air bearing guides. The proposed scanner can be installed on a conventional XY stage with long strokes to improve the positioning accuracy and settling performance. Major design considerations in developing a high precision scanner are sensor accuracy, actuator properties, structural stability, guide friction, and thermal expansion. Considering these factors, the proposed scanner is made of invar, which has a small thermal expansion coefficient and good structural stiffness. Four voice coil motors drive the scanner, which is suspended by four air bearing pads, in the x, y, and θ directions. The scanner's position is measured by three laser interferometers which decouple the scanner from the conventional stage. The mirror blocks reflecting the laser beams are fixed using viscoelastic sheets, ensuring that the scanner has a well-damped structural mode. A time delay control algorithm is implemented on the real-time controller to control the scanner. The effectiveness of the proposed scanner is verified experimentally.

  18. Recent micro-CT scanner developments at UGCT

    NASA Astrophysics Data System (ADS)

    Dierick, Manuel; Van Loo, Denis; Masschaele, Bert; Van den Bulcke, Jan; Van Acker, Joris; Cnudde, Veerle; Van Hoorebeke, Luc

    2014-04-01

    This paper describes two X-ray micro-CT scanners which were recently developed to extend the experimental possibilities of microtomography research at the Centre for X-ray Tomography (www.ugct.ugent.be) of the Ghent University (Belgium). The first scanner, called Nanowood, is a wide-range CT scanner with two X-ray sources (160 kVmax) and two detectors, resolving features down to 0.4 μm in small samples, but allowing samples up to 35 cm to be scanned. This is a sample size range of 3 orders of magnitude, making this scanner well suited for imaging multi-scale materials such as wood, stone, etc. Besides the traditional cone-beam acquisition, Nanowood supports helical acquisition, and it can generate images with significant phase-contrast contributions. The second scanner, known as the Environmental micro-CT scanner (EMCT), is a gantry based micro-CT scanner with variable magnification for scanning objects which are not easy to rotate in a standard micro-CT scanner, for example because they are physically connected to external experimental hardware such as sensor wiring, tubing or others. This scanner resolves 5 μm features, covers a field-of-view of about 12 cm wide with an 80 cm vertical travel range. Both scanners will be extensively described and characterized, and their potential will be demonstrated with some key application results.

  19. Simultaneous EEG-fMRI at ultra-high field: artifact prevention and safety assessment.

    PubMed

    Jorge, João; Grouiller, Frédéric; Ipek, Özlem; Stoermer, Robert; Michel, Christoph M; Figueiredo, Patrícia; van der Zwaag, Wietske; Gruetter, Rolf

    2015-01-15

    The simultaneous recording of scalp electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) can provide unique insights into the dynamics of human brain function, and the increased functional sensitivity offered by ultra-high field fMRI opens exciting perspectives for the future of this multimodal approach. However, simultaneous recordings are susceptible to various types of artifacts, many of which scale with magnetic field strength and can seriously compromise both EEG and fMRI data quality in recordings above 3T. The aim of the present study was to implement and characterize an optimized setup for simultaneous EEG-fMRI in humans at 7 T. The effects of EEG cable length and geometry for signal transmission between the cap and amplifiers were assessed in a phantom model, with specific attention to noise contributions from the MR scanner coldheads. Cable shortening (down to 12 cm from cap to amplifiers) and bundling effectively reduced environment noise by up to 84% in average power and 91% in inter-channel power variability. Subject safety was assessed and confirmed via numerical simulations of RF power distribution and temperature measurements on a phantom model, building on the limited existing literature at ultra-high field. MRI data degradation effects due to the EEG system were characterized via B0 and B1(+) field mapping on a human volunteer, demonstrating important, although not prohibitive, B1 disruption effects. With the optimized setup, simultaneous EEG-fMRI acquisitions were performed on 5 healthy volunteers undergoing two visual paradigms: an eyes-open/eyes-closed task, and a visual evoked potential (VEP) paradigm using reversing-checkerboard stimulation. EEG data exhibited clear occipital alpha modulation and average VEPs, respectively, with concomitant BOLD signal changes. On a single-trial level, alpha power variations could be observed with relative confidence on all trials; VEP detection was more limited, although

  20. Autism spectrum disorder, functional MRI and MR spectroscopy: possibilities and challenges

    PubMed Central

    Hugdahl, Kenneth; Beyer, Mona K.; Brix, Maiken; Ersland, Lars

    2012-01-01

    Background In this article we provide an overview of the use of the functional magnetic resonance imaging (fMRI) and MR spectroscopy (MRS) in studies of autism spectrum disorders (ASD). We moreover provide preliminary data using these measures in cases of children with ASD and healthy controls. A hypothesis was that ASD children would show aberrant brain activation in the prefrontal and parietal cortex in an oddball stimulus situation, with predictable and unpredictable deviant tone stimuli, as an index of resistance to change in the ASD children. We also hypothesized that glutamate and GABA metabolite levels would differ between the two groups. Methods fMRI images were acquired from a GE Signa HDx 3T MR scanner, as were the MRS data. Behavioral data were acquired as response accuracy to the deviant tone stimulus. The tone stimuli were presented in a standard fMRI ON-OFF box-car paradigim. Results The fMRI results showed reduced brain activation in the ASD cases compared to the controls, preferably in the inferior and superior frontal gyrus, posterior temporal lobe, and superior and inferior parietal lobule. These areas make up an effort mode network (EMN), being activated in response to cognitive effort. The MRS results also showed differences between the groups. Discussion The results are discussed in a theoretical framework of resistance to unexpected changes in the environment in ASD children, and how this could have a neurobiological underpinning. The results are also discussed in relation to the brain-gut link, and the possibility that ASD may have a microbial link. A limitation with the study is the few cases reported and the preliminary quality of the results. PMID:23990828

  1. Radiofrequency artefacts in echoplanar imaging induced by two 1.5 T MR scanners in close proximity

    PubMed Central

    Li, X; Cui, J; Christopasak, S P; Kumar, A

    2014-01-01

    Objective: The purpose of this study was to assess radio frequency (RF) artefacts in echoplanar imaging (EPI) induced by two 1.5 T MR scanners in close proximity and to find an effective method to correct them. Methods: Based on the intact shielding of rooms, experiments were performed by two MR scanners with similar centre frequencies. Phantom A (PA) was scanned in one scanner by EPI at different bandwidths (BWs). Simultaneously, phantom B was scanned in a fixed sequence for scanning with the other scanner. RF artefact gaps of PA, scanning time and the image signal–noise ratio (SNR) were measured and recorded. Statistical analysis was performed with the repeated-measures analysis of variance test. Based on findings obtained from PA, three healthy volunteers were studied at a conventional BW and a lower BW to observe the artefact variance. Results: EPI RF artefacts were symmetrically situated in both sides of the image following the phase-encoding direction. The gap size of the artefact became larger and the SNR was significantly improved with a narrower BW. RF artefacts with a lower BW in volunteers presented the same characteristic as PA. Conclusion: For EPI RF artefacts produced by two 1.5 T MR scanners with approximately similar centre frequencies, we can reduce BWs in a suitable range to minimize the effect on MRI. Advances in knowledge: MR scanners with the same field strength installed in the same vicinity might produce RF artefacts in the sequence at larger BWs. Reducing BWs properly is effective to control the position of artefacts and improve the image quality. PMID:24712321

  2. Breast MRI scan

    MedlinePlus

    MRI - breast; Magnetic resonance imaging - breast; Breast cancer - MRI; Breast cancer screening - MRI ... the same breast or the other breast after breast cancer has been diagnosed Distinguish between scar tissue and ...

  3. MRI (Magnetic Resonance Imaging)

    MedlinePlus

    ... Procedures Medical Imaging MRI (Magnetic Resonance Imaging) MRI (Magnetic Resonance Imaging) Share Tweet Linkedin Pin it More sharing options Linkedin Pin it Email Print Magnetic Resonance Imaging (MRI) is a medical imaging procedure for making ...

  4. Ocean color imagery: Coastal zone color scanner

    NASA Technical Reports Server (NTRS)

    Hovis, W. A.

    1975-01-01

    Investigations into the feasibility of sensing ocean color from high altitude for determination of chlorophyll and sediment distributions were carried out using sensors on NASA aircraft, coordinated with surface measurements carried out by oceanographic vessels. Spectrometer measurements in 1971 and 1972 led to development of an imaging sensor now flying on a NASA U-2 and the Coastal Zone Color Scanner to fly on Nimbus G in 1978. Results of the U-2 effort show the imaging sensor to be of great value in sensing pollutants in the ocean.

  5. LAPR: An experimental aircraft pushbroom scanner

    NASA Technical Reports Server (NTRS)

    Wharton, S. W.; Irons, J. I.; Heugel, F.

    1980-01-01

    A three band Linear Array Pushbroom Radiometer (LAPR) was built and flown on an experimental basis by NASA at the Goddard Space Flight Center. The functional characteristics of the instrument and the methods used to preprocess the data, including radiometric correction, are described. The radiometric sensitivity of the instrument was tested and compared to that of the Thematic Mapper and the Multispectral Scanner. The radiometric correction procedure was evaluated quantitatively, using laboratory testing, and qualitatively, via visual examination of the LAPR test flight imagery. Although effective radiometric correction could not yet be demonstrated via laboratory testing, radiometric distortion did not preclude the visual interpretation or parallel piped classification of the test imagery.

  6. A laser scanner for 35mm film

    NASA Technical Reports Server (NTRS)

    Callen, W. R.; Weaver, J. E.

    1977-01-01

    The design, construction, and testing of a laser scanning system is described. The scanner was designed to deliver a scanned beam over a 2.54 cm by 2.54 cm or a 5.08 cm by 5.08 cm format. In order to achieve a scan resolution and rate comparable to that of standard television, an acousto-optic deflector was used for one axis of the scan, and a light deflecting galvanometer for deflection along the other axis. The acoustic optic deflector has the capability of random access scan controlled by a digital computer.

  7. Fast wire scanner for intense electron beams

    NASA Astrophysics Data System (ADS)

    Moore, T.; Agladze, N. I.; Bazarov, I. V.; Bartnik, A.; Dobbins, J.; Dunham, B.; Full, S.; Li, Y.; Liu, X.; Savino, J.; Smolenski, K.

    2014-02-01

    We have developed a cost-effective, fast rotating wire scanner for use in accelerators where high beam currents would otherwise melt even carbon wires. This new design uses a simple planetary gear setup to rotate a carbon wire, fixed at one end, through the beam at speeds in excess of 20 m/s. We present results from bench tests, as well as transverse beam profile measurements taken at Cornell's high-brightness energy recovery linac photoinjector, for beam currents up to 35 mA.

  8. A volume scanner for diffuse imaging

    NASA Astrophysics Data System (ADS)

    Vafa, Elham; Roberts, Nicolas; Sharafutdinova, Galiya; Holdsworth, John

    2016-11-01

    Non-invasive optical screening mammography has a significant barrier in the extreme scatter of human tissue at optical wavelengths. A volume scanner suited for high numerical aperture capture of scattered light from diffuse media has been designed, modelled using Trace Pro software and experimentally constructed. Modelling results indicate the presence of an embedded volume with different scatter properties from the bulk yields a measurable difference in the overall scatter pattern and intensity recorded. Work towards a full tomographic reconstruction from scattered light recorded on the two dimensional array detector is currently underway.

  9. Positron Scanner for Locating Brain Tumors

    DOE R&D Accomplishments Database

    Rankowitz, S.; Robertson, J. S.; Higinbotham, W. A.; Rosenblum, M. J.

    1962-03-01

    A system is described that makes use of positron emitting isotopes for locating brain tumors. This system inherently provides more information about the distribution of radioactivity in the head in less time than existing scanners which use one or two detectors. A stationary circular array of 32 scintillation detectors scans a horizontal layer of the head from many directions simultaneously. The data, consisting of the number of counts in all possible coincidence pairs, are coded and stored in the memory of a Two-Dimensional Pulse-Height Analyzer. A unique method of displaying and interpreting the data is described that enables rapid approximate analysis of complex source distribution patterns. (auth)

  10. The Lick Observatory image-dissector scanner.

    NASA Technical Reports Server (NTRS)

    Robinson, L. B.; Wampler, E. J.

    1972-01-01

    A scanner that uses an image dissector to scan the output screen of an image tube has proven to be a sensitive and linear detector for faint astronomical spectra. The image-tube phosphor screen acts as a short-term storage element and allows the system to approach the performance of an ideal multichannel photon counter. Pulses resulting from individual photons, emitted from the output phosphor and detected by the image dissector, trigger an amplifier-discriminator and are counted in a 24-bit, 4096-word circulating memory. Aspects of system performance are discussed, giving attention to linearity, dynamic range, sensitivity, stability, and scattered light properties.

  11. Chitosan-triphosphate nanoparticles for encapsulation of super-paramagnetic iron oxide as an MRI contrast agent.

    PubMed

    Sanjai, Chutimon; Kothan, Suchart; Gonil, Pattarapond; Saesoo, Somsak; Sajomsang, Warayuth

    2014-04-15

    Super-paramagnetic iron oxide nanoparticles (SPIONPs) were encapsulated at various concentrations within chitosan-triphosphate (SPIONPs-CS) nanoparticles using an ionotropic gelation method. The encapsulation of SPIONPs within CS nanoparticles enhanced their dispersion ability in aqueous solution, with all particles being lower than 130 nm in size and having highly positive surface charge. The SPIONPs-CS nanoparticles exhibited crystalline structure and super-paramagnetic behavior, as seen in non-encapsulated SPIONPs. The morphology of SPIONPs-CS nanoparticles showed that they almost spherical in shape. The effect of phantom environments (culture medium and 3% agar solution) on either T1 or T2 weighted MRI was investigated using a clinical 1.5T MRI scanner. The results revealed that 3% agar solution showed relaxation values higher than the culture medium, leading to a significant decrease in the MR image intensity. Our results demonstrated that the SPIONPs-CS nanoparticles can be applied as tissue-specific MRI contrast agents.

  12. Automatic fusion of photogrammetric imagery and laser scanner point clouds

    NASA Astrophysics Data System (ADS)

    Forkuo, Eric Kwabena

    Close-range photogrammetry and the relatively new technology of terrestrial laser scanning can be considered as complementary rather than competitive technologies. For instance, terrestrial laser scanners (TLS) have the ability to rapidly collect high-resolution 3D surface information about an object. The same type of data can be generated using close-range photogrammetric (CRP) techniques, but image disparities common to close-range scenes makes this an operator intensive task. The imaging systems of some TLSs do not have very high radiometric resolution whereas high-resolution digital cameras used in modern CRP do. Finally, TLSs are essentially earth-bound whereas cameras can be moved at will around the object being imaged. This thesis, therefore, explores and attempts to provide a solution to the problems of developing a methodology to fuse terrestrial laser scanner generated 3D data and high-resolution digital images. Four phases of the methodology have been investigated: data pre-processing (fusion of data from the two sensors), automatic measurements (feature detection and correspondence matching), mapping (creation of point cloud visual index), and orientation (calculation of exterior orientation parameters). Individual phases were initially investigated in a manually controlled environment, typically using commercial photogrammetric software, and then combined in a completely automated system. Focusing on the amount of geometric primitives, three different scenes (data set A, data set B, and data set C) representing three levels of complexity (low, medium and high) were scanned with the laser scanner, and for each scan, a 2D photographic image was taken with a digital camera. To overcome the differences in datasets, a hybrid matching (both feature and area-based) algorithm was successfully developed and implemented. The fidelity of the concept of generating synthetic camera images has been tested by determining the exterior orientation of the synthetic

  13. Physics of MRI: a primer.

    PubMed

    Plewes, Donald B; Kucharczyk, Walter

    2012-05-01

    This article is based on an introductory lecture given for the past many years during the "MR Physics and Techniques for Clinicians" course at the Annual Meeting of the ISMRM. This introduction is not intended to be a comprehensive overview of the field, as the subject of magnetic resonance imaging (MRI) physics is large and complex. Rather, it is intended to lay a conceptual foundation by which magnetic resonance image formation can be understood from an intuitive perspective. The presentation is nonmathematical, relying on simple models that take the reader progressively from the basic spin physics of nuclei, through descriptions of how the magnetic resonance signal is generated and detected in an MRI scanner, the foundations of nuclear magnetic resonance (NMR) relaxation, and a discussion of the Fourier transform and its relation to MR image formation. The article continues with a discussion of how magnetic field gradients are used to facilitate spatial encoding and concludes with a development of basic pulse sequences and the factors defining image contrast. Copyright © 2012 Wiley Periodicals, Inc.

  14. 52. View from ground level showing lower radar scanner switch ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    52. View from ground level showing lower radar scanner switch with open port door in radar scanner building 105 showing emanating waveguides from lower switch in vertical run; photograph also shows catwalk to upper scanner switch in upper left side of photograph and structural supports. - Clear Air Force Station, Ballistic Missile Early Warning System Site II, One mile west of mile marker 293.5 on Parks Highway, 5 miles southwest of Anderson, Anderson, Denali Borough, AK

  15. Integrated Electro-optical Laser-Beam Scanners

    NASA Technical Reports Server (NTRS)

    Boord, Warren T.

    1990-01-01

    Scanners using solid-state devices compact, consume little power, and have no moving parts. Integrated electro-optical laser scanner, in conjunction with external lens, points outgoing beam of light in any number of different directions, depending on number of upper electrodes. Offers beam-deflection angles larger than those of acousto-optic scanners. Proposed for such diverse applications as nonimpact laser printing, color imaging, ranging, barcode reading, and robotic vision.

  16. Integrated Electro-optical Laser-Beam Scanners

    NASA Technical Reports Server (NTRS)

    Boord, Warren T.

    1990-01-01

    Scanners using solid-state devices compact, consume little power, and have no moving parts. Integrated electro-optical laser scanner, in conjunction with external lens, points outgoing beam of light in any number of different directions, depending on number of upper electrodes. Offers beam-deflection angles larger than those of acousto-optic scanners. Proposed for such diverse applications as nonimpact laser printing, color imaging, ranging, barcode reading, and robotic vision.

  17. The use of mobile 3D scanners in maxillofacial surgery.

    PubMed

    Peters, Florian; Möhlhenrich, Stephan Christian; Ayoub, Nassim; Goloborodko, Evgeny; Ghassemi, Alireza; Lethaus, Bernd; Hölzle, Frank; Modabber, Ali

    There are many possibilities for the use of three-dimensional (3D) scanners in maxillofacial surgery. This study aimed to investigate whether the bundling and syncing of two 3D scanners has advantages over single-scanner acquisition in terms of scan quality and the time required to scan an object. Therefore, the speed and precision of 3D data acquisition with one scanner versus two synced scanners was measured in 30 subjects. This was done by analyzing the results obtained by scanning test objects attached to the forehead and cheeks of the subjects. Statistical methods included the Student t test for paired samples. Single-scanner recording resulted in significantly lower mean error of measurement than synced recording with two scanners for length (P < 0.001), all frontal/lateral plane angles (P = 0.034, P < 0.001, P = 0.002, P = 0.003), and side/side plane angles (P = 0.014, P < 0.001, P = 0.015, P = 0.011) of the test object on the cheek. Likewise, the single-scanner method resulted in a significantly lowermean error of measurement than the two-scanner method for frontal/lower plane angles (P < 0.001), right/lower plane angles (P < 0.001), and left/lower plane angles (P = 0.002). Conversely, synced recording of data with two scanners resulted in a significant reduction of scanning time (P < 0.001). Compared to data acquisition with a single 3D scanner, the bundling of two 3D scanners resulted in faster scanning times but lower scan quality.

  18. Magnetic resonance imaging: Clinical experience with an open low-field-strength scanner in a resource challenged African state

    PubMed Central

    Ogbole, GI; Adeleye, AO; Adeyinka, AO; Ogunseyinde, OA

    2012-01-01

    Introduction: Despite the fact that an magnetic resonance imaging (MRI) has been in clinical use for over 20 years, its use and availability in Nigeria, a West African state, is still extremely low. Hence, only few publications are available on the clinical experience with MRI from Nigeria. We set out to evaluate our initial clinical experience with a low-field-strength MRI in a Nigeria's foremost university hospital. Materials and Methods: A retrospective review of all studies, performed with an open 0.2 Tesla MAGNETOM Concerto (Siemens Medical) MRI scanner over a 5-year period (2006 - 2010) was conducted. All patients with complete records were evaluated for their clinical and demographic characteristics. Results: The records of 799 MRI studies were available. Patients’ ages ranged from 1 day to 90 years, with a mean of 40.1 years (± 20.7 SD). There were 463 (57.9%) males and 336 (42.1%) females. Over 90% of the studies were requested to evaluate brain or spine lesions. Low back pain represented the commonest (161/799, 20.7%) clinical indication for MRI. The largest number of patients was referred by physicians from surgical specialties (65.6%). Conclusion: The awareness and competence for proper use of MRI in Nigeria appears high. Low back pain is the commonest indication for MRI in our institution, and surgeons make a greater use of the facility. The provision of high-signal strength MRI may be beneficial in making a wider range of applications available to clinicians. PMID:22865963

  19. [How do metallic middle ear implants behave in the MRI?].

    PubMed

    Kwok, P; Waldeck, A; Strutz, J

    2003-01-01

    Magnetic resonance imaging (MRI) has gained in frequency and importance as a diagnostic procedure. In respect to the close anatomical relationship in the temporal bone it is necessary to know whether it is hazardous to patients with metallic middle ear implants regarding displacement and rise in temperature. For the MR image quality artefacts caused by metallic prostheses should be low. Four different stapes prostheses made from titanium, gold, teflon/platinum and teflon/steel, a titanium total ossicular reconstruction prosthesis (TORP) and two ventilation tubes (made from titanium and gold) were tested in a 1.5 Tesla MRI machine regarding their displacement. All objects were first placed in a petri dish, then suspended from a thread and finally immersed in a dish filled with Gadolinium. Temperature changes of the implants were recorded by a pyrometer. None of the implants moved when they were placed in the petri dish or suspended from the thread. On the water surface the teflon/platinum and the teflon/steel pistons adjusted their direction with their axis longitudinally to the MRI scanner opening and the teflon/steel piston floated towards the MRI-machine when put close enough to the scanner opening. No rise in temperature was recorded. All implants showed as little artefacts that would still make an evaluation of the surrounding tissue possible. Patients with any of the metallic middle ear implants that were examined in this study may undergo MRI-investigations without significant adverse effects.

  20. New Methods of Low-Field MRI for Application to Traumatic Brain Injury

    DTIC Science & Technology

    2014-04-01

    TITLE: New Methods of Low-Field MRI for Application to Traumatic Brain Injury PRINCIPAL INVESTIGATOR: Matthew S. Rosen, Ph.D...SUBTITLE New Methods of Low-Field MRI for Application to TBI 5a. CONTRACT NUMBER 5b. GRANT NUMBER W81XWH-11-2-0076 5c. PROGRAM...imaging in a 100 lb scanner based on a rotating permanent magnet array, and free-radical imaging ex vivo as a path toward in vivo applications

  1. Ratiometric MRI sensors based on core-shell nanoparticles for quantitative pH imaging.

    PubMed

    Okada, Satoshi; Mizukami, Shin; Sakata, Takao; Matsumura, Yutaka; Yoshioka, Yoshichika; Kikuchi, Kazuya

    2014-05-21

    Ratiometric MRI sensors consist of paramagnetic cores and pH-sensitive polymer shells. The core-shell nanostructure enables the coexistence of two incompatible NMR relaxation properties in one particle. The sensors show pH sensitivity in transverse relaxivity (r2 ), but not in longitudinal relaxivity (r1 ). Quantitative pH imaging is achieved by measuring the r2 /r1 value with a clinical 3 T MRI scanner.

  2. Data collection and analysis strategies for phMRI.

    PubMed

    Mandeville, Joseph B; Liu, Christina H; Vanduffel, Wim; Marota, John J A; Jenkins, Bruce G

    2014-09-01

    Although functional MRI traditionally has been applied mainly to study changes in task-induced brain function, evolving acquisition methodologies and improved knowledge of signal mechanisms have increased the utility of this method for studying responses to pharmacological stimuli, a technique often dubbed "phMRI". The proliferation of higher magnetic field strengths and the use of exogenous contrast agent have boosted detection power, a critical factor for successful phMRI due to the restricted ability to average multiple stimuli within subjects. Receptor-based models of neurovascular coupling, including explicit pharmacological models incorporating receptor densities and affinities and data-driven models that incorporate weak biophysical constraints, have demonstrated compelling descriptions of phMRI signal induced by dopaminergic stimuli. This report describes phMRI acquisition and analysis methodologies, with an emphasis on data-driven analyses. As an example application, statistically efficient data-driven regressors were used to describe the biphasic response to the mu-opioid agonist remifentanil, and antagonism using dopaminergic and GABAergic ligands revealed modulation of the mesolimbic pathway. Results illustrate the power of phMRI as well as our incomplete understanding of mechanisms underlying the signal. Future directions are discussed for phMRI acquisitions in human studies, for evolving analysis methodologies, and for interpretative studies using the new generation of simultaneous PET/MRI scanners. This article is part of the Special Issue Section entitled 'Neuroimaging in Neuropharmacology'.

  3. An empirical study of scanner system parameters

    NASA Technical Reports Server (NTRS)

    Landgrebe, D.; Biehl, L.; Simmons, W.

    1976-01-01

    The selection of the current combination of parametric values (instantaneous field of view, number and location of spectral bands, signal-to-noise ratio, etc.) of a multispectral scanner is a complex problem due to the strong interrelationship these parameters have with one another. The study was done with the proposed scanner known as Thematic Mapper in mind. Since an adequate theoretical procedure for this problem has apparently not yet been devised, an empirical simulation approach was used with candidate parameter values selected by the heuristic means. The results obtained using a conventional maximum likelihood pixel classifier suggest that although the classification accuracy declines slightly as the IFOV is decreased this is more than made up by an improved mensuration accuracy. Further, the use of a classifier involving both spatial and spectral features shows a very substantial tendency to resist degradation as the signal-to-noise ratio is decreased. And finally, further evidence is provided of the importance of having at least one spectral band in each of the major available portions of the optical spectrum.

  4. Antenna Near-Field Probe Station Scanner

    NASA Technical Reports Server (NTRS)

    Zaman, Afroz J. (Inventor); Lee, Richard Q. (Inventor); Darby, William G. (Inventor); Barr, Philip J. (Inventor); Lambert, Kevin M (Inventor); Miranda, Felix A. (Inventor)

    2011-01-01

    A miniaturized antenna system is characterized non-destructively through the use of a scanner that measures its near-field radiated power performance. When taking measurements, the scanner can be moved linearly along the x, y and z axis, as well as rotationally relative to the antenna. The data obtained from the characterization are processed to determine the far-field properties of the system and to optimize the system. Each antenna is excited using a probe station system while a scanning probe scans the space above the antenna to measure the near field signals. Upon completion of the scan, the near-field patterns are transformed into far-field patterns. Along with taking data, this system also allows for extensive graphing and analysis of both the near-field and far-field data. The details of the probe station as well as the procedures for setting up a test, conducting a test, and analyzing the resulting data are also described.

  5. A study of artefacts in simultaneous PET and MR imaging using a prototype MR compatible PET scanner.

    PubMed

    Slates, R B; Farahani, K; Shao, Y; Marsden, P K; Taylor, J; Summers, P E; Williams, S; Beech, J; Cherry, S R

    1999-08-01

    We have assessed the possibility of artefacts that can arise in attempting to perform simultaneous positron emission tomography (PET) and magnetic resonance imaging (MRI) using a small prototype MR compatible PET scanner (McPET). In these experiments, we examine MR images for any major artefacts or loss in image quality due to inhomogeneities in the magnetic field, radiofrequency interference or susceptibility effects caused by operation of the PET system inside the MR scanner. In addition, possible artefacts in the PET images caused by the static and time-varying magnetic fields or radiofrequency interference from the MR system were investigated. Biological tissue and a T2-weighted spin echo sequence were used to examine susceptibility artefacts due to components of the McPET scanner (scintillator, optical fibres) situated in the MR field of view. A range of commonly used MR pulse sequences was studied while acquiring PET data to look for possible artefacts in either the PET or MR images. Other than a small loss in signal-to-noise using gradient echo sequences, there was no significant interaction between the two imaging systems. Simultaneous PET and MR imaging of simple phantoms was also carried out in different MR systems with field strengths ranging from 0.2 to 4.7 T. The results of these studies demonstrate that it is possible to acquire PET and MR images simultaneously, without any significant artefacts or loss in image quality, using our prototype MR compatible PET scanner.

  6. Was the Scanner Calibration Slide used for its intended purpose?

    PubMed Central

    2011-01-01

    In the article, Scanner calibration revisited, BMC Bioinformatics 2010, 11:361, Dr. Pozhitkov used the Scanner Calibration Slide, a key product of Full Moon BioSystems to generate data in his study of microarray scanner PMT response and proposed a mathematic model for PMT response [1]. In the end, the author concluded that "Full Moon BioSystems calibration slides are inadequate for performing calibration," and recommended "against using these slides." We found these conclusions are seriously flawed and misleading, and his recommendation against using the Scanner Calibration Slide was not properly supported. PMID:21510874

  7. A Compact Vertical Scanner for Atomic Force Microscopes

    PubMed Central

    Park, Jae Hong; Shim, Jaesool; Lee, Dong-Yeon

    2010-01-01

    A compact vertical scanner for an atomic force microscope (AFM) is developed. The vertical scanner is designed to have no interference with the optical microscope for viewing the cantilever. The theoretical stiffness and resonance of the scanner are derived and verified via finite element analysis. An optimal design process that maximizes the resonance frequency is performed. To evaluate the scanner’s performance, experiments are performed to evaluate the travel range, resonance frequency, and feedback noise level. In addition, an AFM image using the proposed vertical scanner is generated. PMID:22163492

  8. Correction of MRI-induced geometric distortions in whole-body small animal PET-MRI

    SciTech Connect

    Frohwein, Lynn J. Schäfers, Klaus P.; Hoerr, Verena; Faber, Cornelius

    2015-07-15

    Purpose: The fusion of positron emission tomography (PET) and magnetic resonance imaging (MRI) data can be a challenging task in whole-body PET-MRI. The quality of the registration between these two modalities in large field-of-views (FOV) is often degraded by geometric distortions of the MRI data. The distortions at the edges of large FOVs mainly originate from MRI gradient nonlinearities. This work describes a method to measure and correct for these kind of geometric distortions in small animal MRI scanners to improve the registration accuracy of PET and MRI data. Methods: The authors have developed a geometric phantom which allows the measurement of geometric distortions in all spatial axes via control points. These control points are detected semiautomatically in both PET and MRI data with a subpixel accuracy. The spatial transformation between PET and MRI data is determined with these control points via 3D thin-plate splines (3D TPS). The transformation derived from the 3D TPS is finally applied to real MRI mouse data, which were acquired with the same scan parameters used in the phantom data acquisitions. Additionally, the influence of the phantom material on the homogeneity of the magnetic field is determined via field mapping. Results: The spatial shift according to the magnetic field homogeneity caused by the phantom material was determined to a mean of 0.1 mm. The results of the correction show that distortion with a maximum error of 4 mm could be reduced to less than 1 mm with the proposed correction method. Furthermore, the control point-based registration of PET and MRI data showed improved congruence after correction. Conclusions: The developed phantom has been shown to have no considerable negative effect on the homogeneity of the magnetic field. The proposed method yields an appropriate correction of the measured MRI distortion and is able to improve the PET and MRI registration. Furthermore, the method is applicable to whole-body small animal

  9. Defect tracking for nanoimprint lithography using optical surface scanner and scanning electron microscope

    NASA Astrophysics Data System (ADS)

    Yu, Zhaoning; Kurataka, Nobuo; Tran, Hieu; Gauzner, Gene

    2016-09-01

    Fast optical surface scanners are used in combination with high-resolution scanning electron microscopes to facilitate the identification and tracking of nanoimprint defects. We have confirmed that hard particles cause permanent template damages during imprint, resulting in repeating imprint defects. Since contaminants encountered during imprint are dominated by hard metal oxide particles capable of causing such damage, stringent pre-imprint substrate screening is a critical requirement in a manufacturing environment.

  10. A novel manipulation method of human body ownership using an fMRI-compatible master-slave system.

    PubMed

    Hara, Masayuki; Salomon, Roy; van der Zwaag, Wietske; Kober, Tobias; Rognini, Giulio; Nabae, Hiroyuki; Yamamoto, Akio; Blanke, Olaf; Higuchi, Toshiro

    2014-09-30

    Bodily self-consciousness has become an important topic in cognitive neuroscience aiming to understand how the brain creates a unified sensation of the self in a body. Specifically, full body illusion (FBI) in which changes in bodily self-consciousness are experimentally introduced by using visual-tactile stimulation has led to improve understanding of these mechanisms. This paper introduces a novel approach to the classic FBI paradigm using a robotic master-slave system which allows us to examine interactions between action and the sense of body ownership in behavioral and MRI experiments. In the proposed approach, the use of the robotic master-slave system enables unique stimulation in which experimental participants can administer tactile cues on their own back using active self-touch. This active self-touch has never been employed in FBI experiments and it allows to test the role of sensorimotor integration and agency (the feeling of control over our actions) in FBI paradigms. The objective of this study is to propose a robotic-haptic platform allowing a new FBI paradigm including the active self-touch in MRI environments. This paper, first, describes the design concept and the performance of the prototype device in the fMRI environment (for 3T and 7T MRI scanners). In addition, the prototype device is applied to a classic FBI experiment, and we verify that the use of the prototype device succeeded in inducing the FBI. These results indicate that the proposed approach has a potential to drive advances in our understanding of human body ownership and agency by allowing novel manipulation and paradigms.

  11. Reproducibility of Brain Morphometry from Short-Term Repeat Clinical MRI Examinations: A Retrospective Study

    PubMed Central

    Liu, Hon-Man; Chen, Shan-Kai; Chen, Ya-Fang; Lee, Chung-Wei; Yeh, Lee-Ren

    2016-01-01

    Purpose To assess the inter session reproducibility of automatic segmented MRI-derived measures by FreeSurfer in a group of subjects with normal-appearing MR images. Materials and Methods After retrospectively reviewing a brain MRI database from our institute consisting of 14,758 adults, those subjects who had repeat scans and had no history of neurodegenerative disorders were selected for morphometry analysis using FreeSurfer. A total of 34 subjects were grouped by MRI scanner model. After automatic segmentation using FreeSurfer, label-wise comparison (involving area, thickness, and volume) was performed on all segmented results. An intraclass correlation coefficient was used to estimate the agreement between sessions. Wilcoxon signed rank test was used to assess the population mean rank differences across sessions. Mean-difference analysis was used to evaluate the difference intervals across scanners. Absolute percent difference was used to estimate the reproducibility errors across the MRI models. Kruskal-Wallis test was used to determine the across-scanner effect. Results The agreement in segmentation results for area, volume, and thickness measurements of all segmented anatomical labels was generally higher in Signa Excite and Verio models when compared with Sonata and TrioTim models. There were significant rank differences found across sessions in some labels of different measures. Smaller difference intervals in global volume measurements were noted on images acquired by Signa Excite and Verio models. For some brain regions, significant MRI model effects were observed on certain segmentation results. Conclusions Short-term scan-rescan reliability of automatic brain MRI morphometry is feasible in the clinical setting. However, since repeatability of software performance is contingent on the reproducibility of the scanner performance, the scanner performance must be calibrated before conducting such studies or before using such software for retrospective

  12. Velocity Measurement in Carotid Artery: Quantitative Comparison of Time-Resolved 3D Phase-Contrast MRI and Image-based Computational Fluid Dynamics

    PubMed Central

    Sarrami-Foroushani, Ali; Nasr Esfahany, Mohsen; Nasiraei Moghaddam, Abbas; Saligheh Rad, Hamidreza; Firouznia, Kavous; Shakiba, Madjid; Ghanaati, Hossein; Wilkinson, Iain David; Frangi, Alejandro Federico

    2015-01-01

    Background: Understanding hemodynamic environment in vessels is important for realizing the mechanisms leading to vascular pathologies. Objectives: Three-dimensional velocity vector field in carotid bifurcation is visualized using TR 3D phase-contrast magnetic resonance imaging (TR 3D PC MRI) and computational fluid dynamics (CFD). This study aimed to present a qualitative and quantitative comparison of the velocity vector field obtained by each technique. Subjects and Methods: MR imaging was performed on a 30-year old male normal subject. TR 3D PC MRI was performed on a 3 T scanner to measure velocity in carotid bifurcation. 3D anatomical model for CFD was created using images obtained from time-of-flight MR angiography. Velocity vector field in carotid bifurcation was predicted using CFD and PC MRI techniques. A statistical analysis was performed to assess the agreement between the two methods. Results: Although the main flow patterns were the same for the both techniques, CFD showed a greater resolution in mapping the secondary and circulating flows. Overall root mean square (RMS) errors for all the corresponding data points in PC MRI and CFD were 14.27% in peak systole and 12.91% in end diastole relative to maximum velocity measured at each cardiac phase. Bland-Altman plots showed a very good agreement between the two techniques. However, this study was not aimed to validate any of methods, instead, the consistency was assessed to accentuate the similarities and differences between Time-resolved PC MRI and CFD. Conclusion: Both techniques provided quantitatively consistent results of in vivo velocity vector fields in right internal carotid artery (RCA). PC MRI represented a good estimation of main flow patterns inside the vasculature, which seems to be acceptable for clinical use. However, limitations of each technique should be considered while interpreting results. PMID:26793288

  13. Journal Club: Shoulder MRI utilization: relationship of physician MRI equipment ownership to negative study frequency.

    PubMed

    Amrhein, Timothy J; Lungren, Matthew P; Paxton, Ben E; Srinivasan, Ramesh; Jung, Sin-Ho; Yu, Miao; Eastwood, James D; Kilani, Ramsey K

    2013-09-01

    The purpose of this article is to determine whether ownership of MRI equipment by ordering physicians influences the frequency of negative shoulder MRI scans. A retrospective review was performed of 1140 consecutive shoulder MRI scans ordered by two separate referring physician groups serving the same geographic community. The first group (financially incentivized) owned the scanners used and received technical fees for their use. The second group (non-financially incentivized) did not own the scanners used and had no direct financial interest. All examinations were performed with identical protocols and were interpreted by a single radiologist group without financial interest in the imaging equipment used. The frequency of negative examinations and the number of abnormalities in each positive study was tabulated for each group. A total of 1140 shoulder MRI scans met inclusion criteria; 255 were negative (142 for the financially incentivized group and 113 for the non-financially incentivized group). There were 25.6% more negative scans in the financially incentivized group (p=0.047). There was no statistically significant difference in the average number of lesions per positive scan (1.67 for the financially incentivized group and 1.71 for the non-financially incentivized group; p=0.34). No statistically significant difference was found in the frequency of 19 of 20 examined lesions. Shoulder MRI examinations referred by physicians with a financial interest in the imaging equipment used were significantly more likely to be negative. Positive examinations exhibited no statistically significant difference in the number of lesions per scan or in the frequency of 19 of 20 lesion subtypes. This finding suggests a highly similar distribution and severity of disease among the two patient groups.

  14. High-Dimensional Medial Lobe Morphometry: An Automated MRI Biomarker for the New AD Diagnostic Criteria

    PubMed Central

    Valdivia, Fernando

    2014-01-01

    Introduction. Medial temporal lobe atrophy assessment via magnetic resonance imaging (MRI) has been proposed in recent criteria as an in vivo diagnostic biomarker of Alzheimer's disease (AD). However, practical application of these criteria in a clinical setting will require automated MRI analysis techniques. To this end, we wished to validate our automated, high-dimensional morphometry technique to the hypothetical prediction of future clinical status from baseline data in a cohort of subjects in a large, multicentric setting, compared to currently known clinical status for these subjects. Materials and Methods. The study group consisted of 214 controls, 371 mild cognitive impairment (147 having progressed to probable AD and 224 stable), and 181 probable AD from the Alzheimer's Disease Neuroimaging Initiative, with data acquired on 58 different 1.5 T scanners. We measured the sensitivity and specificity of our technique in a hierarchical fashion, first testing the effect of intensity standardization, then between different volumes of interest, and finally its generalizability for a large, multicentric cohort. Results. We obtained 73.2% prediction accuracy with 79.5% sensitivity for the prediction of MCI progression to clinically probable AD. The positive predictive value was 81.6% for MCI progressing on average within 1.5 (0.3 s.d.) year. Conclusion. With high accuracy, the technique's ability to identify discriminant medial temporal lobe atrophy has been demonstrated in a large, multicentric environment. It is suitable as an aid for clinical diagnostic of AD. PMID:25254139

  15. Neurodevelopmental aspects of spatial navigation: a virtual reality fMRI study.

    PubMed

    Pine, Daniel S; Grun, Joseph; Maguire, Eleanor A; Burgess, Neil; Zarahn, Eric; Koda, Vivian; Fyer, Abby; Szeszko, Philip R; Bilder, Robert M

    2002-02-01

    Navigation in spatial contexts has been studied in diverse species, yielding insights into underlying neural mechanisms and their phylogenetic progression. Spatial navigation in humans is marked by age-related changes that may carry important implications for understanding cortical development. The emergence of "allocentric" processing, reflecting that ability to use viewer-independent spatial abstractions, represents an important developmental change. We used fMRI to map brain regions engaged during memory-guided navigation in a virtual reality environment in adolescents and adults. Blood oxygen level-dependent (BOLD) signal was monitored in eight adolescents and eight adults in a 1.5-T MRI scanner during three conditions: (1) memory-guided navigation (NAV); (2) arrow-guided navigation (ARROW); and (3) fixation (FIX). We quantified navigation ability during scanning and allocentric memory after scanning, based on subjects' ability to label a previously unseen, aerial view of the town. Adolescents and adults exhibited similar memory-guided navigation ability, but adults exhibited superior allocentric memory ability. Memory-guided navigation ability during scanning correlated with BOLD change between NAV/ARROWS in various regions, including a right frontal and right-anterior medial temporal lobe region. Age group and allocentric memory together explained significant variance in BOLD change in temporoparietal association cortex and the cerebellum, particularly in the left hemisphere. Consistent with developmental models, these findings relate maturation in the coding of spatial information to functional changes in a distributed, left-lateralized neural network.

  16. CONSIDERATIONS FOR MRI STUDY DESIGN AND IMPLEMENTATION IN PEDIATRIC AND CLINICAL POPULATIONS

    PubMed Central

    Greene, Deanna J.; Black, Kevin J.; Schlaggar, Bradley L.

    2016-01-01

    Human neuroimaging, specifically magnetic resonance imaging (MRI), is being used with increasing popularity to study brain structure and function in development and disease. When applying these methods to developmental and clinical populations, careful consideration must be taken with regard to study design and implementation. In this article, we discuss two major considerations particularly pertinent to brain research in special populations. First, we discuss considerations for subject selection and characterization, including issues related to comorbid conditions, medication status, and clinical assessment. Second, we discuss methods and considerations for acquisition of adequate, useable MRI data. Given that children and patients may experience anxiety with the scanner environment, preventing participation, and that they have a higher risk of motion artifact, resulting in data loss, successful subject compliance and data acquisition are not trivial tasks. We conclude that, as researchers, we must consider a number of issues when using neuroimaging tools to study children and patients, and we should thoughtfully justify our choices of methods and study design. PMID:26754461

  17. Scanner OPC signatures: automatic vendor-to-vendor OPE matching

    NASA Astrophysics Data System (ADS)

    Renwick, Stephen P.

    2009-03-01

    As 193nm lithography continues to be stretched and the k1 factor decreases, optical proximity correction (OPC) has become a vital part of the lithographer's tool kit. Unfortunately, as is now well known, the design variations of lithographic scanners from different vendors cause them to have slightly different optical-proximity effect (OPE) behavior, meaning that they print features through pitch in distinct ways. This in turn means that their response to OPC is not the same, and that an OPC solution designed for a scanner from Company 1 may or may not work properly on a scanner from Company 2. Since OPC is not inexpensive, that causes trouble for chipmakers using more than one brand of scanner. Clearly a scanner-matching procedure is needed to meet this challenge. Previously, automatic matching has only been reported for scanners of different tool generations from the same manufacturer. In contrast, scanners from different companies have been matched using expert tuning and adjustment techniques, frequently requiring laborious test exposures. Automatic matching between scanners from Company 1 and Company 2 has remained an unsettled problem. We have recently solved this problem and introduce a novel method to perform the automatic matching. The success in meeting this challenge required three enabling factors. First, we recognized the strongest drivers of OPE mismatch and are thereby able to reduce the information needed about a tool from another supplier to that information readily available from all modern scanners. Second, we developed a means of reliably identifying the scanners' optical signatures, minimizing dependence on process parameters that can cloud the issue. Third, we carefully employed standard statistical techniques, checking for robustness of the algorithms used and maximizing efficiency. The result is an automatic software system that can predict an OPC matching solution for scanners from different suppliers without requiring expert intervention.

  18. In Amnio MRI of Mouse Embryos

    PubMed Central

    Roberts, Thomas A.; Norris, Francesca C.; Carnaghan, Helen; Savery, Dawn; Wells, Jack A.; Siow, Bernard; Scambler, Peter J.; Pierro, Agostino; De Coppi, Paolo; Eaton, Simon; Lythgoe, Mark F.

    2014-01-01

    Mouse embryo imaging is conventionally carried out on ex vivo embryos excised from the amniotic sac, omitting vital structures and abnormalities external to the body. Here, we present an in amnio MR imaging methodology in which the mouse embryo is retained in the amniotic sac and demonstrate how important embryonic structures can be visualised in 3D with high spatial resolution (100 µm/px). To illustrate the utility of in amnio imaging, we subsequently apply the technique to examine abnormal mouse embryos with abdominal wall defects. Mouse embryos at E17.5 were imaged and compared, including three normal phenotype embryos, an abnormal embryo with a clear exomphalos defect, and one with a suspected gastroschisis phenotype. Embryos were excised from the mother ensuring the amnion remained intact and stereo microscopy was performed. Embryos were next embedded in agarose for 3D, high resolution MRI on a 9.4T scanner. Identification of the abnormal embryo phenotypes was not possible using stereo microscopy or conventional ex vivo MRI. Using in amnio MRI, we determined that the abnormal embryos had an exomphalos phenotype with varying severities. In amnio MRI is ideally suited to investigate the complex relationship between embryo and amnion, together with screening for other abnormalities located outside of the mouse embryo, providing a valuable complement to histology and existing imaging methods available to the phenotyping community. PMID:25330230

  19. In amnio MRI of mouse embryos.

    PubMed

    Roberts, Thomas A; Norris, Francesca C; Carnaghan, Helen; Savery, Dawn; Wells, Jack A; Siow, Bernard; Scambler, Peter J; Pierro, Agostino; De Coppi, Paolo; Eaton, Simon; Lythgoe, Mark F

    2014-01-01

    Mouse embryo imaging is conventionally carried out on ex vivo embryos excised from the amniotic sac, omitting vital structures and abnormalities external to the body. Here, we present an in amnio MR imaging methodology in which the mouse embryo is retained in the amniotic sac and demonstrate how important embryonic structures can be visualised in 3D with high spatial resolution (100 µm/px). To illustrate the utility of in amnio imaging, we subsequently apply the technique to examine abnormal mouse embryos with abdominal wall defects. Mouse embryos at E17.5 were imaged and compared, including three normal phenotype embryos, an abnormal embryo with a clear exomphalos defect, and one with a suspected gastroschisis phenotype. Embryos were excised from the mother ensuring the amnion remained intact and stereo microscopy was performed. Embryos were next embedded in agarose for 3D, high resolution MRI on a 9.4T scanner. Identification of the abnormal embryo phenotypes was not possible using stereo microscopy or conventional ex vivo MRI. Using in amnio MRI, we determined that the abnormal embryos had an exomphalos phenotype with varying severities. In amnio MRI is ideally suited to investigate the complex relationship between embryo and amnion, together with screening for other abnormalities located outside of the mouse embryo, providing a valuable complement to histology and existing imaging methods available to the phenotyping community.

  20. Influence of MRI field strength on clinical decision making in knee cartilage injury - A case study.

    PubMed

    Cashman, Glenn; Attariwala, Raj

    2014-12-01

    To increase clinicians' awareness of the differences in image resolution and potential diagnostic accuracy between small and large-field MR Scanners. To present an example of a clinical decision making challenge in how to proceed when knee MRI and clinical findings don't agree. A 38 year old female mountain biker presented with knee pain and clinical features strongly suggestive of a torn meniscus or loose bodies. An initial MRI using a small field strength (0.18T) scanner was reported as normal. Her clinical presentation was suspicious enough that a repeat MRI on a high-field (1.5T) scanner was ordered. The second MRI included high resolution 3D volumetric imaging which revealed cartilage damage and loose bodies. The patient was treated with arthroscopic surgery which confirmed the presence of meniscal and chondral injury and resulted in notable improvement in the patient's symptoms. Clinicians should consider scanner quality and diagnostic accuracy before discounting strongly suggestive clinical history and examination findings when MRIs are reported as normal.

  1. Quantitative Clinical Evaluation of a Simultaneous PETI MRI Breast Imaging System

    SciTech Connect

    Schlyer D. J.; Schlyer, D.J.

    2013-04-03

    A prototype simultaneous PET-MRI breast scanner has been developed for conducting clinical studies with the goal of obtaining high resolution anatomical and functional information in the same scan which can lead to faster and better diagnosis, reduction of unwanted biopsies, and better patient care.

  2. A Forced-Attention Dichotic Listening fMRI Study on 113 Subjects

    ERIC Educational Resources Information Center

    Kompus, Kristiina; Specht, Karsten; Ersland, Lars; Juvodden, Hilde T.; van Wageningen, Heidi; Hugdahl, Kenneth; Westerhausen, Rene

    2012-01-01

    We report fMRI and behavioral data from 113 subjects on attention and cognitive control using a variant of the classic dichotic listening paradigm with pairwise presentations of consonant-vowel syllables. The syllable stimuli were presented in a block-design while subjects were in the MR scanner. The subjects were instructed to pay attention to…

  3. A Forced-Attention Dichotic Listening fMRI Study on 113 Subjects

    ERIC Educational Resources Information Center

    Kompus, Kristiina; Specht, Karsten; Ersland, Lars; Juvodden, Hilde T.; van Wageningen, Heidi; Hugdahl, Kenneth; Westerhausen, Rene

    2012-01-01

    We report fMRI and behavioral data from 113 subjects on attention and cognitive control using a variant of the classic dichotic listening paradigm with pairwise presentations of consonant-vowel syllables. The syllable stimuli were presented in a block-design while subjects were in the MR scanner. The subjects were instructed to pay attention to…

  4. Temporal analysis of multispectral scanner data.

    NASA Technical Reports Server (NTRS)

    Richardson, A. J.; Wiegand, C. L.; Torline, R. J.

    1973-01-01

    Multispectral scanner reflectance data were sampled for bare soil, cotton, sorghum, corn, and citrus at four dates during a growing season (April, May, June, and July 1969) to develop a time-dependent signature for crop and soil discrimination. Discrimination tests were conducted for single-date and multidate formats using training and test data sets. For classifications containing several crops, the multidate or temporal approach improved discrimination compared with the single-date approach. The multidate approach also preserved recognition accuracy better in going from training fields to test fields than the single-date analysis. The spectral distinctiveness of bare soil versus vegetation resulted in essentially equal discrimination using single-date versus multidate data for those two categories.

  5. Quadrupole resonance scanner for narcotics detection

    NASA Astrophysics Data System (ADS)

    Shaw, Julian D.; Moeller, C. R.; Magnuson, Erik E.; Sheldon, Alan G.

    1994-10-01

    Interest in non-invasive, non-hazardous, bulk detection technologies for narcotics interdiction has risen over the last few years. As part of our continuing research and development programs in detection of narcotics and explosives using sensitive magnetic measuring devices, we present the first commercially available prototype Quadrupole Resonance (QR) scanner for narcotics detection. The portable narcotics detection system was designed in modular form such that a single QR base system could be easily used with a variety of custom detection heads. The QR system presented in this paper is suitable for scanning items up to 61 X 35 X 13 cm in size, and was designed to scan mail packages and briefcase-sized items for the presence of narcotics. System tests have shown that detection sensitivity is comparable that obtained in laboratory systems.

  6. Temporal analysis of multispectral scanner data.

    NASA Technical Reports Server (NTRS)

    Richardson, A. J.; Wiegand, C. L.; Torline, R. J.

    1973-01-01

    Multispectral scanner reflectance data were sampled for bare soil, cotton, sorghum, corn, and citrus at four dates during a growing season (April, May, June, and July 1969) to develop a time-dependent signature for crop and soil discrimination. Discrimination tests were conducted for single-date and multidate formats using training and test data sets. For classifications containing several crops, the multidate or temporal approach improved discrimination compared with the single-date approach. The multidate approach also preserved recognition accuracy better in going from training fields to test fields than the single-date analysis. The spectral distinctiveness of bare soil versus vegetation resulted in essentially equal discrimination using single-date versus multidate data for those two categories.

  7. Laser excited confocal microscope fluorescence scanner and method

    DOEpatents

    Mathies, R.A.; Peck, K.

    1992-02-25

    A fluorescent scanner is designed for scanning the fluorescence from a fluorescence labeled separated sample on a sample carrier. The scanner includes a confocal microscope for illuminating a predetermined volume of the sample carrier and/or receiving and processing fluorescence emissions from the volume to provide a display of the separated sample. 8 figs.

  8. 5. SITE BUILDING 002 SCANNER BUILDING AT "A" ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    5. SITE BUILDING 002 - SCANNER BUILDING - AT "A" FACE (ON SOUTH SIDE) LOOKING DIRECTLY UP RADAR SYSTEM EMITTER/ANTENNA ARRAY FACE WITH 90MM STANDARD LENS. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  9. 6. SITE BUILDING 002 SCANNER BUILDING AT "A" ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. SITE BUILDING 002 - SCANNER BUILDING - AT "A" FACE (ON SOUTH SIDE) LOOKING DIRECTLY UP RADAR SYSTEM EMITTER/ANTENNA ARRAY FACE WITH 65MM WIDE ANGLE LENS. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  10. 9. SITE BUILDING 002 SCANNER BUILDING LOOKING AT ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    9. SITE BUILDING 002 - SCANNER BUILDING - LOOKING AT "C" FACE RADAR SYSTEM EMITTER/ANTENNA. VIEW IS LOOKING SOUTH 30° EAST (NOTE: "C" FACE NOT IN USE AT FACILITY). - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  11. 34. SITE BUILDING 002 SCANNER BUILDING ROOM 105 ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    34. SITE BUILDING 002 - SCANNER BUILDING - ROOM 105 - CHILLER ROOM, SHOWING SINGLE COMPRESSOR, LIQUID CHILLERS AND "CHILLED WATER RETURN", COOLING TOWER 'TOWER WATER RETURN" AND 'TOWER WATER SUPPLY" LINES. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  12. 10. SITE BUILDING 002 SCANNER BUILDING LOOKING AT ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    10. SITE BUILDING 002 - SCANNER BUILDING - LOOKING AT SOUTHWEST CORNER "B" FACE AND "C" FACE ON WEST AND EVAPORATIVE COOLING TOWER AT NORTH. VIEW IS LOOKING NORTH 45° EAST. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  13. 25. SITE BUILDING 002 SCANNER BUILDING OPERATIONS CENTER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    25. SITE BUILDING 002 - SCANNER BUILDING - OPERATIONS CENTER - MWOC IN OPERATION AT 1930 ZULU TIME, 26 OCTOBER, 1999. MWOC SCREEN ALSO SHOWS RADAR "FACE A" AND "FACE B" ACTIVE STATUS. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  14. 21. SITE BUILDING 002 SCANNER BUILDING LOOKING AT ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    21. SITE BUILDING 002 - SCANNER BUILDING - LOOKING AT DISC STORAGE SYSTEMS A AND B (A OR B ARE REDUNDANT SYSTEMS), ONE MAINFRAME COMPUTER ON LINE, ONE ON STANDBY WITH STORAGE TAPE, ONE ON STANDBY WITHOUT TAPE INSTALLED. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  15. 27. SITE BUILDING 002 SCANNER BUILDING OPERATIONS CENTER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    27. SITE BUILDING 002 - SCANNER BUILDING - OPERATIONS CENTER - MWOC MONITOR NO. 4 IN OPERATION AT 2002 ZULU, OCTOBER 26, 1999 CAPE COD, AS PAVE PAWS. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  16. 20. SITE BUILDING 002 SCANNER BUILDING IN COMPUTER ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    20. SITE BUILDING 002 - SCANNER BUILDING - IN COMPUTER ROOM LOOKING AT "CONSOLIDATED MAINTENANCE OPERATIONS CENTER" JOB AREA AND OPERATION WORK CENTER. TASKS INCLUDE RADAR MAINTENANCE, COMPUTER MAINTENANCE, CYBER COMPUTER MAINTENANCE AND RELATED ACTIVITIES. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  17. 12. SITE BUILDING 002 SCANNER BUILDING MAIN ENTRANCE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    12. SITE BUILDING 002 - SCANNER BUILDING - MAIN ENTRANCE LOOKING AT MAIN ENTRANCE TO TECHNICAL FACILITY, GROUND LEVEL. VIEW IS LOOKING SOUTH 20° EAST. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  18. 19. SITE BUILDING 002 SCANNER BUILDING AIR POLICE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    19. SITE BUILDING 002 - SCANNER BUILDING - AIR POLICE SITE SECURITY OFFICE WITH "SITE PERIMETER STATUS PANEL" AND REAL TIME VIDEO DISPLAY OUTPUT FROM VIDEO CAMERA SYSTEM AT SECURITY FENCE LOCATIONS. - Cape Cod Air Station, Technical Facility-Scanner Building & Power Plant, Massachusetts Military Reservation, Sandwich, Barnstable County, MA

  19. 21 CFR 892.1300 - Nuclear rectilinear scanner.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Nuclear rectilinear scanner. 892.1300 Section 892.1300 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1300 Nuclear rectilinear scanner. (a...

  20. 21 CFR 892.1300 - Nuclear rectilinear scanner.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Nuclear rectilinear scanner. 892.1300 Section 892.1300 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1300 Nuclear rectilinear scanner. (a...