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Sample records for mri fluoroscopic image

  1. Computerized tomography using video recorded fluoroscopic images

    NASA Technical Reports Server (NTRS)

    Kak, A. C.; Jakowatz, C. V., Jr.; Baily, N. A.; Keller, R. A.

    1975-01-01

    A computerized tomographic imaging system is examined which employs video-recorded fluoroscopic images as input data. By hooking the video recorder to a digital computer through a suitable interface, such a system permits very rapid construction of tomograms.

  2. Fluoroscopic image-guided intervention system for transbronchial localization

    NASA Astrophysics Data System (ADS)

    Rai, Lav; Keast, Thomas M.; Wibowo, Henky; Yu, Kun-Chang; Draper, Jeffrey W.; Gibbs, Jason D.

    2012-02-01

    Reliable transbronchial access of peripheral lung lesions is desirable for the diagnosis and potential treatment of lung cancer. This procedure can be difficult, however, because accessory devices (e.g., needle or forceps) cannot be reliably localized while deployed. We present a fluoroscopic image-guided intervention (IGI) system for tracking such bronchoscopic accessories. Fluoroscopy, an imaging technology currently utilized by many bronchoscopists, has a fundamental shortcoming - many lung lesions are invisible in its images. Our IGI system aligns a digitally reconstructed radiograph (DRR) defined from a pre-operative computed tomography (CT) scan with live fluoroscopic images. Radiopaque accessory devices are readily apparent in fluoroscopic video, while lesions lacking a fluoroscopic signature but identifiable in the CT scan are superimposed in the scene. The IGI system processing steps consist of: (1) calibrating the fluoroscopic imaging system; (2) registering the CT anatomy with its depiction in the fluoroscopic scene; (3) optical tracking to continually update the DRR and target positions as the fluoroscope is moved about the patient. The end result is a continuous correlation of the DRR and projected targets with the anatomy depicted in the live fluoroscopic video feed. Because both targets and bronchoscopic devices are readily apparent in arbitrary fluoroscopic orientations, multiplane guidance is straightforward. The system tracks in real-time with no computational lag. We have measured a mean projected tracking accuracy of 1.0 mm in a phantom and present results from an in vivo animal study.

  3. Fluoroscopic tumor tracking for image-guided lung cancer radiotherapy

    NASA Astrophysics Data System (ADS)

    Lin, Tong; Cerviño, Laura I.; Tang, Xiaoli; Vasconcelos, Nuno; Jiang, Steve B.

    2009-02-01

    Accurate lung tumor tracking in real time is a keystone to image-guided radiotherapy of lung cancers. Existing lung tumor tracking approaches can be roughly grouped into three categories: (1) deriving tumor position from external surrogates; (2) tracking implanted fiducial markers fluoroscopically or electromagnetically; (3) fluoroscopically tracking lung tumor without implanted fiducial markers. The first approach suffers from insufficient accuracy, while the second may not be widely accepted due to the risk of pneumothorax. Previous studies in fluoroscopic markerless tracking are mainly based on template matching methods, which may fail when the tumor boundary is unclear in fluoroscopic images. In this paper we propose a novel markerless tumor tracking algorithm, which employs the correlation between the tumor position and surrogate anatomic features in the image. The positions of the surrogate features are not directly tracked; instead, we use principal component analysis of regions of interest containing them to obtain parametric representations of their motion patterns. Then, the tumor position can be predicted from the parametric representations of surrogates through regression. Four regression methods were tested in this study: linear and two-degree polynomial regression, artificial neural network (ANN) and support vector machine (SVM). The experimental results based on fluoroscopic sequences of ten lung cancer patients demonstrate a mean tracking error of 2.1 pixels and a maximum error at a 95% confidence level of 4.6 pixels (pixel size is about 0.5 mm) for the proposed tracking algorithm.

  4. A novel marker enhancement filter (MEF) for fluoroscopic images

    NASA Astrophysics Data System (ADS)

    Peshko, Olesya; Davidson, Timothy N.; Modersitzki, Jan; Terlaky, Tamás; Moseley, Douglas J.

    2014-03-01

    To enhance the measurements of radio-opaque cylindrical fiducial markers in low contrast x-ray and fluoroscopic images, a novel nonlinear marker enhancement filter (MEF) has been designed. It was primarily developed to assist in automatic initialization of a tracking procedure for intra-fraction organ motion analysis in fluoroscopic sequences. Conventional procedures were not able to provide sufficient improvement due to the complications of noise, small marker size, cylindrical shape and multiple orientations, intensity variations of the background, and the presence of overlaying anatomical measurements in this application. The proposed MEF design is based on the principles of linear scale space. It includes measures that assess the probability of each pixel to belong to a marker measurement, morphological operations, and a novel contrast enhancement function for standardization of the filter output. The MEF was tested on fluoroscopic images of two phantoms and three prostate patients, and was shown to perform better or comparable to the existing filters in terms of marker enhancement and background suppression, while performing significantly better in marker shape preservation.

  5. Cryo-balloon catheter localization in fluoroscopic images

    NASA Astrophysics Data System (ADS)

    Kurzendorfer, Tanja; Brost, Alexander; Jakob, Carolin; Mewes, Philip W.; Bourier, Felix; Koch, Martin; Kurzidim, Klaus; Hornegger, Joachim; Strobel, Norbert

    2013-03-01

    Minimally invasive catheter ablation has become the preferred treatment option for atrial fibrillation. Although the standard ablation procedure involves ablation points set by radio-frequency catheters, cryo-balloon catheters have even been reported to be more advantageous in certain cases. As electro-anatomical mapping systems do not support cryo-balloon ablation procedures, X-ray guidance is needed. However, current methods to provide support for cryo-balloon catheters in fluoroscopically guided ablation procedures rely heavily on manual user interaction. To improve this, we propose a first method for automatic cryo-balloon catheter localization in fluoroscopic images based on a blob detection algorithm. Our method is evaluated on 24 clinical images from 17 patients. The method successfully detected the cryoballoon in 22 out of 24 images, yielding a success rate of 91.6 %. The successful localization achieved an accuracy of 1.00 mm +/- 0.44 mm. Even though our methods currently fails in 8.4 % of the images available, it still offers a significant improvement over manual methods. Furthermore, detecting a landmark point along the cryo-balloon catheter can be a very important step for additional post-processing operations.

  6. MRI (Magnetic Resonance Imaging)

    MedlinePlus

    ... and Procedures Medical Imaging MRI (Magnetic Resonance Imaging) MRI (Magnetic Resonance Imaging) Share Tweet Linkedin Pin it More sharing options ... usually given through an IV in the arm. MRI Research Programs at FDA Magnetic Resonance Imaging (MRI) ...

  7. Simulation system for understanding the lag effect in fluoroscopic images.

    PubMed

    Tanaka, Rie; Kawashima, Hiroki; Ichikawa, Katsuhiro; Matsubara, Kosuke; Iida, Hiroji; Sanada, Shigeru

    2013-07-01

    Real-time tumor tracking in external radiotherapy can be achieved by diagnostic (kV) X-ray imaging with a dynamic flat-panel detector (FPD). It is crucial to understand the effects of image lag for real-time tumor tracking. Our purpose in this study was to develop a lag simulation system based on the image lag properties of an FPD system. Image lag properties were measured on flat-field images both in direct- and indirect-conversion dynamic FPDs. A moving target with image lag was simulated based on the lag properties in all combinations of FPD types, imaging rates, exposure doses, and target speeds, and then compared with actual moving targets for investigation of the reproducibility of image lag. Image lag was simulated successfully and agreed well with the actual lag as well as with the predicted effect. In the indirect-conversion FPD, a higher dose caused greater image lag on images. In contrast, there were no significant differences among dose levels in a direct-conversion FPD. There were no relationships between target speed and amount of image blurring in either type of FPD. The maximum contour blurring and the rate of increase in pixel value due to image lag were 1.1 mm and 10.0 %, respectively, in all combinations of imaging parameters examined in this study. Blurred boundaries and changes in pixel value due to image lag were estimated under various imaging conditions with use of the simulation system. Our system would be helpful for a better understanding of the effects of image lag in fluoroscopic images.

  8. Combined MRI and Fluoroscopic Guided Radiofrequency Ablation of a Renal Tumor

    SciTech Connect

    Fotiadis, Nikolas I.; Sabharwal, Tarun; Gangi, Afshin; Adam, Andreas

    2009-01-15

    Percutaneous CT- and ultrasound-guided radiofrequency ablation of renal cell carcinoma (RCC) has been shown to have very promising medium-term results. We present a unique case of recurrent RCC after partial nephrectomy in a patient with a single kidney and impaired renal function. This tumor could not be visualized either with CT or with ultrasound. A combination of magnetic resonance imaging and fluoroscopic guidance was used, to the best of our knowledge for the first time, to ablate the tumor with radiofrequency. The patient was cancer-free and off dialysis at 30-month follow up.

  9. 3D fluoroscopic image estimation using patient-specific 4DCBCT-based motion models

    NASA Astrophysics Data System (ADS)

    Dhou, S.; Hurwitz, M.; Mishra, P.; Cai, W.; Rottmann, J.; Li, R.; Williams, C.; Wagar, M.; Berbeco, R.; Ionascu, D.; Lewis, J. H.

    2015-05-01

    3D fluoroscopic images represent volumetric patient anatomy during treatment with high spatial and temporal resolution. 3D fluoroscopic images estimated using motion models built using 4DCT images, taken days or weeks prior to treatment, do not reliably represent patient anatomy during treatment. In this study we developed and performed initial evaluation of techniques to develop patient-specific motion models from 4D cone-beam CT (4DCBCT) images, taken immediately before treatment, and used these models to estimate 3D fluoroscopic images based on 2D kV projections captured during treatment. We evaluate the accuracy of 3D fluoroscopic images by comparison to ground truth digital and physical phantom images. The performance of 4DCBCT-based and 4DCT-based motion models are compared in simulated clinical situations representing tumor baseline shift or initial patient positioning errors. The results of this study demonstrate the ability for 4DCBCT imaging to generate motion models that can account for changes that cannot be accounted for with 4DCT-based motion models. When simulating tumor baseline shift and patient positioning errors of up to 5 mm, the average tumor localization error and the 95th percentile error in six datasets were 1.20 and 2.2 mm, respectively, for 4DCBCT-based motion models. 4DCT-based motion models applied to the same six datasets resulted in average tumor localization error and the 95th percentile error of 4.18 and 5.4 mm, respectively. Analysis of voxel-wise intensity differences was also conducted for all experiments. In summary, this study demonstrates the feasibility of 4DCBCT-based 3D fluoroscopic image generation in digital and physical phantoms and shows the potential advantage of 4DCBCT-based 3D fluoroscopic image estimation when there are changes in anatomy between the time of 4DCT imaging and the time of treatment delivery.

  10. 3D fluoroscopic image estimation using patient-specific 4DCBCT-based motion models

    PubMed Central

    Dhou, Salam; Hurwitz, Martina; Mishra, Pankaj; Cai, Weixing; Rottmann, Joerg; Li, Ruijiang; Williams, Christopher; Wagar, Matthew; Berbeco, Ross; Ionascu, Dan; Lewis, John H.

    2015-01-01

    3D fluoroscopic images represent volumetric patient anatomy during treatment with high spatial and temporal resolution. 3D fluoroscopic images estimated using motion models built using 4DCT images, taken days or weeks prior to treatment, do not reliably represent patient anatomy during treatment. In this study we develop and perform initial evaluation of techniques to develop patient-specific motion models from 4D cone-beam CT (4DCBCT) images, taken immediately before treatment, and use these models to estimate 3D fluoroscopic images based on 2D kV projections captured during treatment. We evaluate the accuracy of 3D fluoroscopic images by comparing to ground truth digital and physical phantom images. The performance of 4DCBCT- and 4DCT- based motion models are compared in simulated clinical situations representing tumor baseline shift or initial patient positioning errors. The results of this study demonstrate the ability for 4DCBCT imaging to generate motion models that can account for changes that cannot be accounted for with 4DCT-based motion models. When simulating tumor baseline shift and patient positioning errors of up to 5 mm, the average tumor localization error and the 95th percentile error in six datasets were 1.20 and 2.2 mm, respectively, for 4DCBCT-based motion models. 4DCT-based motion models applied to the same six datasets resulted in average tumor localization error and the 95th percentile error of 4.18 and 5.4 mm, respectively. Analysis of voxel-wise intensity differences was also conducted for all experiments. In summary, this study demonstrates the feasibility of 4DCBCT-based 3D fluoroscopic image generation in digital and physical phantoms, and shows the potential advantage of 4DCBCT-based 3D fluoroscopic image estimation when there are changes in anatomy between the time of 4DCT imaging and the time of treatment delivery. PMID:25905722

  11. 21 CFR 892.1650 - Image-intensified fluoroscopic x-ray system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Image-intensified fluoroscopic x-ray system. 892.1650 Section 892.1650 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1650...

  12. 21 CFR 892.1650 - Image-intensified fluoroscopic x-ray system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Image-intensified fluoroscopic x-ray system. 892.1650 Section 892.1650 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1650...

  13. 21 CFR 892.1660 - Non-image-intensified fluoroscopic x-ray system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Non-image-intensified fluoroscopic x-ray system. 892.1660 Section 892.1660 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1660...

  14. 21 CFR 892.1650 - Image-intensified fluoroscopic x-ray system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Image-intensified fluoroscopic x-ray system. 892.1650 Section 892.1650 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1650...

  15. 21 CFR 892.1650 - Image-intensified fluoroscopic x-ray system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Image-intensified fluoroscopic x-ray system. 892.1650 Section 892.1650 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1650...

  16. 21 CFR 892.1650 - Image-intensified fluoroscopic x-ray system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Image-intensified fluoroscopic x-ray system. 892.1650 Section 892.1650 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1650...

  17. 21 CFR 892.1660 - Non-image-intensified fluoroscopic x-ray system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Non-image-intensified fluoroscopic x-ray system. 892.1660 Section 892.1660 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1660...

  18. 21 CFR 892.1660 - Non-image-intensified fluoroscopic x-ray system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Non-image-intensified fluoroscopic x-ray system. 892.1660 Section 892.1660 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1660...

  19. 21 CFR 892.1660 - Non-image-intensified fluoroscopic x-ray system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Non-image-intensified fluoroscopic x-ray system. 892.1660 Section 892.1660 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1660...

  20. 21 CFR 892.1660 - Non-image-intensified fluoroscopic x-ray system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Non-image-intensified fluoroscopic x-ray system. 892.1660 Section 892.1660 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1660...

  1. MR cone-beam CT fusion image overlay for fluoroscopically guided percutaneous biopsies in pediatric patients.

    PubMed

    Thakor, Avnesh S; Patel, Premal A; Gu, Richard; Rea, Vanessa; Amaral, Joao; Connolly, Bairbre L

    2016-03-01

    Lesions only visible on magnetic resonance (MR) imaging cannot easily be targeted for image-guided biopsy using ultrasound or X-rays but instead require MR guidance with MR-compatible needles and long procedure times (acquisition of multiple MR sequences). We developed an alternative method for performing these difficult biopsies in a standard interventional suite, by fusing MR with cone-beam CT images. The MR cone-beam CT fusion image is then used as an overlay to guide a biopsy needle to the target area under live fluoroscopic guidance. Advantages of this technique include (i) the ability for it to be performed in a conventional interventional suite, (ii) three-dimensional planning of the needle trajectory using cross-sectional imaging, (iii) real-time fluoroscopic guidance for needle trajectory correction and (iv) targeting within heterogeneous lesions based on MR signal characteristics to maximize the potential biopsy yield.

  2. 4DCBCT-based motion modeling and 3D fluoroscopic image generation for lung cancer radiotherapy

    NASA Astrophysics Data System (ADS)

    Dhou, Salam; Hurwitz, Martina; Mishra, Pankaj; Berbeco, Ross; Lewis, John

    2015-03-01

    A method is developed to build patient-specific motion models based on 4DCBCT images taken at treatment time and use them to generate 3D time-varying images (referred to as 3D fluoroscopic images). Motion models are built by applying Principal Component Analysis (PCA) on the displacement vector fields (DVFs) estimated by performing deformable image registration on each phase of 4DCBCT relative to a reference phase. The resulting PCA coefficients are optimized iteratively by comparing 2D projections captured at treatment time with projections estimated using the motion model. The optimized coefficients are used to generate 3D fluoroscopic images. The method is evaluated using anthropomorphic physical and digital phantoms reproducing real patient trajectories. For physical phantom datasets, the average tumor localization error (TLE) and (95th percentile) in two datasets were 0.95 (2.2) mm. For digital phantoms assuming superior image quality of 4DCT and no anatomic or positioning disparities between 4DCT and treatment time, the average TLE and the image intensity error (IIE) in six datasets were smaller using 4DCT-based motion models. When simulating positioning disparities and tumor baseline shifts at treatment time compared to planning 4DCT, the average TLE (95th percentile) and IIE were 4.2 (5.4) mm and 0.15 using 4DCT-based models, while they were 1.2 (2.2) mm and 0.10 using 4DCBCT-based ones, respectively. 4DCBCT-based models were shown to perform better when there are positioning and tumor baseline shift uncertainties at treatment time. Thus, generating 3D fluoroscopic images based on 4DCBCT-based motion models can capture both inter- and intra- fraction anatomical changes during treatment.

  3. Dynamic imaging of pulmonary ventilation. Description of a novel digital fluoroscopic system.

    PubMed

    Kiuru, A; Svedström, E; Kuuluvainen, I

    1991-03-01

    A new fluoroscopic imaging device consisting of an AT-microcomputer and a digital image memory unit has been used in experimental and clinical ventilation studies during a 2-year period. Digital images with 256 shades of gray were collected during one to 3 ventilation cycles at the rate of 6 to 25 images/s and stored on an optical laser disc. Both subtracted time interval difference (TID-) images and images relative, for example, to the mean image of the cycle (REL-images) were produced. The series of images could also be evaluated dynamically using animation sequences or analyzed using region of interest calculations. The method gave dynamic information with adequate spatial resolution and was easy to use in clinical practice. The radiation dose was kept low due to the high kilovoltage and heavy beam filtration technique. In experimental studies the software enabled flexible measurements of physiological pulmonary parameters.

  4. The Prognostic Value of Enhanced-MRI and Fluoroscopic Factors for Predicting the Effects of Transforaminal Steroid Injections on Lumbosacral Radiating Pain

    PubMed Central

    2016-01-01

    Objective To investigate the predictive value of enhanced-magnetic resonance imaging (MRI) and fluoroscopic factors regarding the effects of transforaminal epidural steroid injections (TFESIs) in low back pain (LBP) patients with lumbosacral radiating pain. Methods A total of 51 patients who had LBP with radiating pain were recruited between January 2011 and December 2012. The patient data were classified into the two groups ‘favorable group’ and ‘non-favorable group’ after 2 weeks of follow-up results. The favorable group was defined as those with a 50%, or more, reduction of pain severity according to the visual analogue scale (VAS) for back or leg pain. The clinical and radiological data were collected for univariate and multivariate analyses to determine the predictors of the effectiveness of TFESIs between the two groups. Results According to the back or the leg favorable-VAS group, the univariate analysis revealed that the corticosteroid approach for the enhanced nerve root, the proportion of the proximal flow, and the contrast dispersion of epidurography are respectively statistically significant relative to the other factors. Lastly, the multiple logistic regression analysis showed a significant association between the corticosteroid approach and the enhanced nerve root in the favorable VAS group. Conclusion Among the variables, MRI showed that the corticosteroid approach for the enhanced target root is the most important prognostic factor in the predicting of the clinical parameters of the favorable TFESIs group. PMID:28119838

  5. Real-time image-processing algorithm for markerless tumour tracking using X-ray fluoroscopic imaging

    PubMed Central

    2014-01-01

    Objective: To ensure accuracy in respiratory-gating treatment, X-ray fluoroscopic imaging is used to detect tumour position in real time. Detection accuracy is strongly dependent on image quality, particularly positional differences between the patient and treatment couch. We developed a new algorithm to improve the quality of images obtained in X-ray fluoroscopic imaging and report the preliminary results. Methods: Two oblique X-ray fluoroscopic images were acquired using a dynamic flat panel detector (DFPD) for two patients with lung cancer. The weighting factor was applied to the DFPD image in respective columns, because most anatomical structures, as well as the treatment couch and port cover edge, were aligned in the superior–inferior direction when the patient lay on the treatment couch. The weighting factors for the respective columns were varied until the standard deviation of the pixel values within the image region was minimized. Once the weighting factors were calculated, the quality of the DFPD image was improved by applying the factors to multiframe images. Results: Applying the image-processing algorithm produced substantial improvement in the quality of images, and the image contrast was increased. The treatment couch and irradiation port edge, which were not related to a patient's position, were removed. The average image-processing time was 1.1 ms, showing that this fast image processing can be applied to real-time tumour-tracking systems. Conclusion: These findings indicate that this image-processing algorithm improves the image quality in patients with lung cancer and successfully removes objects not related to the patient. Advances in knowledge: Our image-processing algorithm might be useful in improving gated-treatment accuracy. PMID:24661056

  6. Multiresolution parametric estimation of transparent motions and denoising of fluoroscopic images.

    PubMed

    Auvray, Vincent; Liénard, Jean; Bouthemy, Patrick

    2005-01-01

    We describe a novel multiresolution parametric framework to estimate transparent motions typically present in X-Ray exams. Assuming the presence if two transparent layers, it computes two affine velocity fields by minimizing an appropriate objective function with an incremental Gauss-Newton technique. We have designed a realistic simulation scheme of fluoroscopic image sequences to validate our method on data with ground truth and different levels of noise. An experiment on real clinical images is also reported. We then exploit this transparent-motion estimation method to denoise two layers image sequences using a motion-compensated estimation method. In accordance with theory, we show that we reach a denoising factor of 2/3 in a few iterations without bringing any local artifacts in the image sequence.

  7. Contrast changes in fluoroscopic imaging systems and statistical variations of these changes

    NASA Technical Reports Server (NTRS)

    Bailey, N. A.

    1973-01-01

    Experimental studies have indicated that: (1) The response of digitized fluoroscopic imaging systems is linear systems is linear with contrast over a rather wide range of absorber and cavity thicknesses. (2) Contrast changes associated with the addition of aluminum, iodine containing contrast agents and air of thicknesses 1mm or less can be detected with a 95% confidence level. (3) The standard deviation associated with such determination using clinically available X-ray generators and video disc recording is less than 1 percent. A large flat screen X-ray image intensifier has been constructed and some preliminary results obtained. Sensitivity achieved makes dose reduction a factor often greater than previously reported for a system using a conventional X-ray image intensifier.

  8. Accurate 3D kinematic measurement of temporomandibular joint using X-ray fluoroscopic images

    NASA Astrophysics Data System (ADS)

    Yamazaki, Takaharu; Matsumoto, Akiko; Sugamoto, Kazuomi; Matsumoto, Ken; Kakimoto, Naoya; Yura, Yoshiaki

    2014-04-01

    Accurate measurement and analysis of 3D kinematics of temporomandibular joint (TMJ) is very important for assisting clinical diagnosis and treatment of prosthodontics and orthodontics, and oral surgery. This study presents a new 3D kinematic measurement technique of the TMJ using X-ray fluoroscopic images, which can easily obtain the TMJ kinematic data in natural motion. In vivo kinematics of the TMJ (maxilla and mandibular bone) is determined using a feature-based 2D/3D registration, which uses beads silhouette on fluoroscopic images and 3D surface bone models with beads. The 3D surface models of maxilla and mandibular bone with beads were created from CT scans data of the subject using the mouthpiece with the seven strategically placed beads. In order to validate the accuracy of pose estimation for the maxilla and mandibular bone, computer simulation test was performed using five patterns of synthetic tantalum beads silhouette images. In the clinical applications, dynamic movement during jaw opening and closing was conducted, and the relative pose of the mandibular bone with respect to the maxilla bone was determined. The results of computer simulation test showed that the root mean square errors were sufficiently smaller than 1.0 mm and 1.0 degree. In the results of clinical application, during jaw opening from 0.0 to 36.8 degree of rotation, mandibular condyle exhibited 19.8 mm of anterior sliding relative to maxillary articular fossa, and these measurement values were clinically similar to the previous reports. Consequently, present technique was thought to be suitable for the 3D TMJ kinematic analysis.

  9. Fluoroscopic-guided radiofrequency ablation of the basivertebral nerve: application and analysis with multiple imaging modalities in an ovine model (Invited Paper)

    NASA Astrophysics Data System (ADS)

    Bergeron, Jeffrey A.; Eskey, Cliff J.; Attawia, Mohammed; Patel, Samit J.; Ryan, Thomas P.; Pellegrino, Richard; Sutton, Jeffrey; Crombie, John; Paul, B. T.; Hoopes, P. J.

    2005-04-01

    Pathologic involvement of the basivertebral nerve, an intraosseous vertebral nerve found in humans and most mammalian species, may play a role in some forms of back pain. This study was designed to assess the feasibility and effects of the percutaneous delivery of radiofrequency (RF) energy to thermally ablate the basivertebral nerve in the lumbar vertebrae of mature sheep. Using fluoroscopic guidance, a RF bipolar device was placed and a thermal dose delivered to lumbar vertebral bodies in sheep. Post-treatment assessment included multiple magnetic resonance imaging (MRI) techniques and computed tomography (CT). These data were analyzed and correlated to histopathology and morphometry findings to describe the cellular and boney structural changes resulting from the treatment. Imaging modalities MRI and CT can be implemented to non-invasively describe treatment region and volume, marrow cellular effects, and bone density alterations immediately following RF treatment and during convalescence. Such imaging can be utilized to assess treatment effects and refine the thermal dose to vertebral body volume ratio used in treatment planning. This information will be used to improve the therapeutic ratio and develop a treatment protocol for human applications.

  10. Optimization of multi-image pose recovery of fluoroscope tracking (FTRAC) fiducial in an image-guided femoroplasty system

    NASA Astrophysics Data System (ADS)

    Liu, Wen P.; Armand, Mehran; Otake, Yoshito; Taylor, Russell H.

    2011-03-01

    Percutaneous femoroplasty [1], or femoral bone augmentation, is a prospective alternative treatment for reducing the risk of fracture in patients with severe osteoporosis. We are developing a surgical robotics system that will assist orthopaedic surgeons in planning and performing a patient-specific, augmentation of the femur with bone cement. This collaborative project, sponsored by the National Institutes of Health (NIH), has been the topic of previous publications [2],[3] from our group. This paper presents modifications to the pose recovery of a fluoroscope tracking (FTRAC) fiducial during our process of 2D/3D registration of X-ray intraoperative images to preoperative CT data. We show improved automata of the initial pose estimation as well as lower projection errors with the advent of a multiimage pose optimization step.

  11. Magnetic Resonance Imaging (MRI)

    MedlinePlus

    ... problems (in men)Path to improved healthIf your primary care doctor determines that you should have an MRI, ... may not apply to everyone. Talk to your family doctor to find out if this information applies to ...

  12. A simple method for the generation of organ and vessel contours from roentgenographic or fluoroscopic images

    NASA Technical Reports Server (NTRS)

    Newell, J. D.; Keller, R. A.; Baily, N. A.

    1974-01-01

    A simple method for outlining or contouring any area defined by a change in film density or fluoroscopic screen intensity is described. The entire process, except for the positioning of an electronic window, is accomplished using a small computer having appropriate softwave. The electronic window is operator positioned over the area to be processed. The only requirement is that the window be large enough to encompass the total area to be considered.

  13. SU-E-J-01: 3D Fluoroscopic Image Estimation From Patient-Specific 4DCBCT-Based Motion Models

    SciTech Connect

    Dhou, S; Hurwitz, M; Lewis, J; Mishra, P

    2014-06-01

    Purpose: 3D motion modeling derived from 4DCT images, taken days or weeks before treatment, cannot reliably represent patient anatomy on the day of treatment. We develop a method to generate motion models based on 4DCBCT acquired at the time of treatment, and apply the model to estimate 3D time-varying images (referred to as 3D fluoroscopic images). Methods: Motion models are derived through deformable registration between each 4DCBCT phase, and principal component analysis (PCA) on the resulting displacement vector fields. 3D fluoroscopic images are estimated based on cone-beam projections simulating kV treatment imaging. PCA coefficients are optimized iteratively through comparison of these cone-beam projections and projections estimated based on the motion model. Digital phantoms reproducing ten patient motion trajectories, and a physical phantom with regular and irregular motion derived from measured patient trajectories, are used to evaluate the method in terms of tumor localization, and the global voxel intensity difference compared to ground truth. Results: Experiments included: 1) assuming no anatomic or positioning changes between 4DCT and treatment time; and 2) simulating positioning and tumor baseline shifts at the time of treatment compared to 4DCT acquisition. 4DCBCT were reconstructed from the anatomy as seen at treatment time. In case 1) the tumor localization error and the intensity differences in ten patient were smaller using 4DCT-based motion model, possible due to superior image quality. In case 2) the tumor localization error and intensity differences were 2.85 and 0.15 respectively, using 4DCT-based motion models, and 1.17 and 0.10 using 4DCBCT-based models. 4DCBCT performed better due to its ability to reproduce daily anatomical changes. Conclusion: The study showed an advantage of 4DCBCT-based motion models in the context of 3D fluoroscopic images estimation. Positioning and tumor baseline shift uncertainties were mitigated by the 4DCBCT

  14. Functional Imaging: CT and MRI

    PubMed Central

    van Beek, Edwin JR; Hoffman, Eric A

    2008-01-01

    Synopsis Numerous imaging techniques permit evaluation of regional pulmonary function. Contrast-enhanced CT methods now allow assessment of vasculature and lung perfusion. Techniques using spirometric controlled MDCT allow for quantification of presence and distribution of parenchymal and airway pathology, Xenon gas can be employed to assess regional ventilation of the lungs and rapid bolus injections of iodinated contrast agent can provide quantitative measure of regional parenchymal perfusion. Advances in magnetic resonance imaging (MRI) of the lung include gadolinium-enhanced perfusion imaging and hyperpolarized helium imaging, which can allow imaging of pulmonary ventilation and .measurement of the size of emphysematous spaces. PMID:18267192

  15. Magnetic Resonance Imaging (MRI): Brain (For Parents)

    MedlinePlus

    ... to 2-Year-Old Magnetic Resonance Imaging (MRI): Brain KidsHealth > For Parents > Magnetic Resonance Imaging (MRI): Brain ... child may be given headphones to listen to music or earplugs to block the noise, and will ...

  16. Magnetic Resonance Imaging (MRI) -- Head

    MedlinePlus

    ... provides detailed images of blood vessels in the brain—often without the need for contrast material. See the MRA page for more information. MRI can detect stroke at a very early stage by mapping the motion of water molecules in the tissue. ...

  17. Threshold contrast detail detectability measurement of the fluoroscopic image quality of a dynamic solid-state digital x-ray image detector.

    PubMed

    Davies, A G; Cowen, A R; Kengyelics, S M; Bury, R F; Bruijns, T J

    2001-01-01

    Solid-state digital x-ray imaging detectors of flat-panel construction will play an increasingly important role in future medical imaging facilities. Solid-state detectors that will support both dynamic (including fluoroscopic) and radiographic image recording are under active development. The image quality of an experimental solid-state digital x-ray image detector operating in a continuous fluoroscopy mode has been investigated. The threshold contrast detail detectability (TCDD) technique was used to compare the fluoroscopic imaging performance of an experimental dynamic solid-state digital x-ray image detector with that of a reference image intensifier television (IITV) fluoroscopy system. The reference system incorporated Plumbicon TV. Results were presented as a threshold detection index, or H(T)(A), curves. Measurements were made over a range of mean entrance air kerma (EAK) rates typically used in conventional IITV fluoroscopy. At the upper and mid EAK rate range (440 and 220 nGy/s) the solid-state detector outperformed the reference IITV fluoroscopy system as measured by TCDD performance. At the lowest measured EAK rate (104 nGy/s), the solid-state detector produces slightly inferior TCDD performance compared with the reference system. Although not statistically significant at this EAK rate, the difference will increase as EAK is lowered further. Overall the TCDD results and early clinical experiences support the proposition that a current design of dynamic solid-state detector produces image quality competitive with that of modern IITV fluoroscopy systems. These findings encourage the development of compact and versatile universal x-ray imaging systems based upon solid-state detector technology to support R & F and vascular/interventional applications.

  18. Investigation of first ray mobility during gait by kinematic fluoroscopic imaging-a novel method

    PubMed Central

    2012-01-01

    Background It is often suggested that sagittal instability at the first tarso-metatarsal joint level is a primary factor for hallux valgus and that sagittal instability increases with the progression of the deformity. The assessment of the degree of vertical instability is usually made by clinical evaluation while any measurements mostly refer to a static assessment of medial ray mobility (i.e. the plantar/dorsal flexion in the sagittal plane). Testing methods currently available cannot attribute the degree of mobility to the corresponding anatomical joints making up the medial column of the foot. The aim of this study was to develop a technique which allows for a quantification of the in-vivo sagittal mobility of the joints of the medial foot column during the roll-over process under full weight bearing. Methods Mobility of first ray bones was investigated by dynamic distortion-free fluoroscopy (25 frames/s) of 14 healthy volunteers and 8 patients with manifested clinical instability of the first ray. A CAD-based evaluation method allowed the determination of mobility and relative displacements and rotations of the first ray bones within the sagittal plane during the stance phase of gait. Results Total flexion of the first ray was found to be 13.63 (SD 6.14) mm with the healthy volunteers and 13.06 (SD 8.01) mm with the patients (resolution: 0.245 mm/pixel). The dorsiflexion angle was 5.27 (SD 2.34) degrees in the healthy volunteers and increased to 5.56 (SD 3.37) degrees in the patients. Maximum rotations were found at the naviculo-cuneiform joints and least at the first tarso-metatarsal joint level in both groups. Conclusions Dynamic fluoroscopic assessment has been shown to be a valuable tool for characterisation of the kinematics of the joints of the medial foot column during gait. A significant difference in first ray flexion and angular rotation between the patients and healthy volunteers however could not be found. PMID:22316084

  19. 21 CFR 1020.32 - Fluoroscopic equipment.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... fluoroscopic image receptor using photographic film or a video camera when the x-ray source is operated in a...-hold feature that are not recorded. (C) When a mode of operation has an optional high-level control...

  20. Three-dimensional kinematic estimation of mobile-bearing total knee arthroplasty from x-ray fluoroscopic images

    NASA Astrophysics Data System (ADS)

    Yamazaki, Takaharu; Futai, Kazuma; Tomita, Tetsuya; Sato, Yoshinobu; Yoshikawa, Hideki; Tamura, Shinichi; Sugamoto, Kazuomi

    2011-03-01

    To achieve 3D kinematic analysis of total knee arthroplasty (TKA), 2D/3D registration techniques, which use X-ray fluoroscopic images and computer-aided design (CAD) model of the knee implant, have attracted attention in recent years. These techniques could provide information regarding the movement of radiopaque femoral and tibial components but could not provide information of radiolucent polyethylene insert, because the insert silhouette on X-ray image did not appear clearly. Therefore, it was difficult to obtain 3D kinemaitcs of polyethylene insert, particularly mobile-bearing insert that move on the tibial component. This study presents a technique and the accuracy for 3D kinematic analysis of mobile-bearing insert in TKA using X-ray fluoroscopy, and finally performs clinical applications. For a 3D pose estimation technique of the mobile-bearing insert in TKA using X-ray fluoroscopy, tantalum beads and CAD model with its beads are utilized, and the 3D pose of the insert model is estimated using a feature-based 2D/3D registration technique. In order to validate the accuracy of the present technique, experiments including computer simulation test were performed. The results showed the pose estimation accuracy was sufficient for analyzing mobile-bearing TKA kinematics (the RMS error: about 1.0 mm, 1.0 degree). In the clinical applications, seven patients with mobile-bearing TKA in deep knee bending motion were studied and analyzed. Consequently, present technique enables us to better understand mobile-bearing TKA kinematics, and this type of evaluation was thought to be helpful for improving implant design and optimizing TKA surgical techniques.

  1. Functional MRI using regularized parallel imaging acquisition.

    PubMed

    Lin, Fa-Hsuan; Huang, Teng-Yi; Chen, Nan-Kuei; Wang, Fu-Nien; Stufflebeam, Steven M; Belliveau, John W; Wald, Lawrence L; Kwong, Kenneth K

    2005-08-01

    Parallel MRI techniques reconstruct full-FOV images from undersampled k-space data by using the uncorrelated information from RF array coil elements. One disadvantage of parallel MRI is that the image signal-to-noise ratio (SNR) is degraded because of the reduced data samples and the spatially correlated nature of multiple RF receivers. Regularization has been proposed to mitigate the SNR loss originating due to the latter reason. Since it is necessary to utilize static prior to regularization, the dynamic contrast-to-noise ratio (CNR) in parallel MRI will be affected. In this paper we investigate the CNR of regularized sensitivity encoding (SENSE) acquisitions. We propose to implement regularized parallel MRI acquisitions in functional MRI (fMRI) experiments by incorporating the prior from combined segmented echo-planar imaging (EPI) acquisition into SENSE reconstructions. We investigated the impact of regularization on the CNR by performing parametric simulations at various BOLD contrasts, acceleration rates, and sizes of the active brain areas. As quantified by receiver operating characteristic (ROC) analysis, the simulations suggest that the detection power of SENSE fMRI can be improved by regularized reconstructions, compared to unregularized reconstructions. Human motor and visual fMRI data acquired at different field strengths and array coils also demonstrate that regularized SENSE improves the detection of functionally active brain regions.

  2. Functional MRI Using Regularized Parallel Imaging Acquisition

    PubMed Central

    Lin, Fa-Hsuan; Huang, Teng-Yi; Chen, Nan-Kuei; Wang, Fu-Nien; Stufflebeam, Steven M.; Belliveau, John W.; Wald, Lawrence L.; Kwong, Kenneth K.

    2013-01-01

    Parallel MRI techniques reconstruct full-FOV images from undersampled k-space data by using the uncorrelated information from RF array coil elements. One disadvantage of parallel MRI is that the image signal-to-noise ratio (SNR) is degraded because of the reduced data samples and the spatially correlated nature of multiple RF receivers. Regularization has been proposed to mitigate the SNR loss originating due to the latter reason. Since it is necessary to utilize static prior to regularization, the dynamic contrast-to-noise ratio (CNR) in parallel MRI will be affected. In this paper we investigate the CNR of regularized sensitivity encoding (SENSE) acquisitions. We propose to implement regularized parallel MRI acquisitions in functional MRI (fMRI) experiments by incorporating the prior from combined segmented echo-planar imaging (EPI) acquisition into SENSE reconstructions. We investigated the impact of regularization on the CNR by performing parametric simulations at various BOLD contrasts, acceleration rates, and sizes of the active brain areas. As quantified by receiver operating characteristic (ROC) analysis, the simulations suggest that the detection power of SENSE fMRI can be improved by regularized reconstructions, compared to unregularized reconstructions. Human motor and visual fMRI data acquired at different field strengths and array coils also demonstrate that regularized SENSE improves the detection of functionally active brain regions. PMID:16032694

  3. Magnetic Resonance Imaging (MRI) - Spine

    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 ...

  4. Magnetic Resonance Imaging (MRI) -- Head

    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 ...

  5. Magnetic Resonance Imaging (MRI) Safety

    MedlinePlus

    ... radiation. Instead, MRI uses a powerful magnetic field, radio waves, rapidly changing magnetic fields, and a computer to ... in most of the body's tissues. The applied radio waves then cause these protons to produce signals that ...

  6. 4D flow imaging with MRI

    PubMed Central

    Stankovic, Zoran; Allen, Bradley D.; Garcia, Julio; Jarvis, Kelly B.

    2014-01-01

    Magnetic resonance imaging (MRI) has become an important tool for the clinical evaluation of patients with cardiovascular disease. Since its introduction in the late 1980s, 2-dimensional phase contrast MRI (2D PC-MRI) has become a routine part of standard-of-care cardiac MRI for the assessment of regional blood flow in the heart and great vessels. More recently, time-resolved PC-MRI with velocity encoding along all three flow directions and three-dimensional (3D) anatomic coverage (also termed ‘4D flow MRI’) has been developed and applied for the evaluation of cardiovascular hemodynamics in multiple regions of the human body. 4D flow MRI allows for the comprehensive evaluation of complex blood flow patterns by 3D blood flow visualization and flexible retrospective quantification of flow parameters. Recent technical developments, including the utilization of advanced parallel imaging techniques such as k-t GRAPPA, have resulted in reasonable overall scan times, e.g., 8-12 minutes for 4D flow MRI of the aorta and 10-20 minutes for whole heart coverage. As a result, the application of 4D flow MRI in a clinical setting has become more feasible, as documented by an increased number of recent reports on the utility of the technique for the assessment of cardiac and vascular hemodynamics in patient studies. A number of studies have demonstrated the potential of 4D flow MRI to provide an improved assessment of hemodynamics which might aid in the diagnosis and therapeutic management of cardiovascular diseases. The purpose of this review is to describe the methods used for 4D flow MRI acquisition, post-processing and data analysis. In addition, the article provides an overview of the clinical applications of 4D flow MRI and includes a review of applications in the heart, thoracic aorta and hepatic system. PMID:24834414

  7. Functional lung imaging using hyperpolarized gas MRI.

    PubMed

    Fain, Sean B; Korosec, Frank R; Holmes, James H; O'Halloran, Rafael; Sorkness, Ronald L; Grist, Thomas M

    2007-05-01

    The noninvasive assessment of lung function using imaging is increasingly of interest for the study of lung diseases, including chronic obstructive pulmonary disease (COPD) and asthma. Hyperpolarized gas MRI (HP MRI) has demonstrated the ability to detect changes in ventilation, perfusion, and lung microstructure that appear to be associated with both normal lung development and disease progression. The physical characteristics of HP gases and their application to MRI are presented with an emphasis on current applications. Clinical investigations using HP MRI to study asthma, COPD, cystic fibrosis, pediatric chronic lung disease, and lung transplant are reviewed. Recent advances in polarization, pulse sequence development for imaging with Xe-129, and prototype low magnetic field systems dedicated to lung imaging are highlighted as areas of future development for this rapidly evolving technology.

  8. Fluoroscopic x-ray imaging with amorphous silicon thin-film arrays

    NASA Astrophysics Data System (ADS)

    Schiebel, Ulrich W.; Conrads, Norbert; Jung, Norbert; Weibrecht, Martin; Wieczorek, Herfried K.; Zaengel, Thomas T.; Powell, M. J.; French, I. D.; Glasse, C.

    1994-05-01

    The dream of an all-solid state large area x-ray image sensor with digital readout and full dynamic performance will most probably find a first realization in 2D thin-film amorphous silicon arrays. In this paper we address in particular the evaluation of the limits of the signal/noise ratio in this concept. Using small prototype detectors measurements of MTF and noise power spectra have been made as a function of x-ray dose. The results are given in terms of the detective quantum efficiency as a function of dose and spatial frequency. We further present an analysis of the different noise sources and their dependence on the detector parameters, and we provide estimates on the maximum signals that may be achieved per unit dose. The intrinsic lag of the amorphous silicon photodiodes causes a second problem area with this type of x-ray detectors. Especially in radiography/fluoroscopy mixed applications, memory effects may not be negligible.

  9. Investigation on effect of image lag in fluoroscopic images obtained with a dynamic flat-panel detector (FPD) on accuracy of target tracking in radiotherapy.

    PubMed

    Tanaka, Rie; Ichikawa, Katsuhiro; Mori, Shinichiro; Dobashi, Suguru; Kumagai, Motoki; Kawashima, Hiroki; Minohara, Shinichi; Sanada, Sigeru

    2010-01-01

    Real-time tumor tracking in external radiotherapy can be achieved by diagnostic (kV) X-ray imaging with a dynamic flat-panel detector (FPD). The purpose of this study was to address image lag in target tracking and its influence on the accuracy of tumor tracking. Fluoroscopic images were obtained using a direct type of dynamic FPD. Image lag properties were measured without test devices according to IEC 62220-1. Modulation transfer function (MTF) and profile curves were measured on the edges of a moving tungsten plate at movement rate of 10 and 20 mm/s, covering lung tumor movement of normal breathing. A lung tumor and metal sphere with blurred edge due to image lag was simulated using the results and then superimposed on breathing chest radiographs of a patient. The moving target with and without image lag was traced using a template-matching technique. In the results, the image lag for the first frame after X-ray cutoff was 2.0% and decreased to less than 0.1% in the fifth frame. In the measurement of profile curves on the edges of static and moving tungsten material plates, the effect of image lag was seen as blurred edges of the plate. The blurred edges of a moving target were indicated as reduction of MTF. However, the target could be traced within an error of ± 5 mm. The results indicated that there was no effect of image lag on target tracking in usual breathing speed in a radiotherapy situation.

  10. Developments in boron magnetic resonance imaging (MRI)

    SciTech Connect

    Schweizer, M.

    1995-11-01

    This report summarizes progress during the past year on maturing Boron-11 magnetic resonance imaging (MRI) methodology for noninvasive determination of BNCT agents (BSH) spatially in time. Three major areas are excerpted: (1) Boron-11 MRI of BSH distributions in a canine intracranial tumor model and the first human glioblastoma patient, (2) whole body Boron-11 MRI of BSH pharmacokinetics in a rat flank tumor model, and (3) penetration of gadolinium salts through the BBB as a function of tumor growth in the canine brain.

  11. Magnetic Resonance Imaging (MRI): Lumbar Spine (For Parents)

    MedlinePlus

    ... If You Have Questions en español Resonancia magnética: columna lumbar What It Is Magnetic resonance imaging (MRI) ... MORE ON THIS TOPIC Magnetic Resonance Imaging (MRI): Cervical Spine Lumbar Puncture (Spinal Tap) Magnetic Resonance Imaging ( ...

  12. 21 CFR 1020.32 - Fluoroscopic equipment.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... images from the fluoroscopic image receptor, except computed tomography x-ray systems manufactured on or... section of the useful beam at any SID. The x-ray tube used for fluoroscopy shall not produce x-rays unless... manufactured after February 25, 1978, when the angle between the image receptor and the beam axis of the...

  13. 21 CFR 1020.32 - Fluoroscopic equipment.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... images from the fluoroscopic image receptor, except computed tomography x-ray systems manufactured on or... section of the useful beam at any SID. The x-ray tube used for fluoroscopy shall not produce x-rays unless... manufactured after February 25, 1978, when the angle between the image receptor and the beam axis of the...

  14. 21 CFR 1020.32 - Fluoroscopic equipment.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... images from the fluoroscopic image receptor, except computed tomography x-ray systems manufactured on or... section of the useful beam at any SID. The x-ray tube used for fluoroscopy shall not produce x-rays unless... manufactured after February 25, 1978, when the angle between the image receptor and the beam axis of the...

  15. 21 CFR 1020.32 - Fluoroscopic equipment.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... images from the fluoroscopic image receptor, except computed tomography x-ray systems manufactured on or... section of the useful beam at any SID. The x-ray tube used for fluoroscopy shall not produce x-rays unless... manufactured after February 25, 1978, when the angle between the image receptor and the beam axis of the...

  16. WE-G-207-06: 3D Fluoroscopic Image Generation From Patient-Specific 4DCBCT-Based Motion Models Derived From Physical Phantom and Clinical Patient Images

    SciTech Connect

    Dhou, S; Cai, W; Hurwitz, M; Rottmann, J; Myronakis, M; Cifter, F; Berbeco, R; Lewis, J; Williams, C; Mishra, P; Ionascu, D

    2015-06-15

    Purpose: Respiratory-correlated cone-beam CT (4DCBCT) images acquired immediately prior to treatment have the potential to represent patient motion patterns and anatomy during treatment, including both intra- and inter-fractional changes. We develop a method to generate patient-specific motion models based on 4DCBCT images acquired with existing clinical equipment and used to generate time varying volumetric images (3D fluoroscopic images) representing motion during treatment delivery. Methods: Motion models are derived by deformably registering each 4DCBCT phase to a reference phase, and performing principal component analysis (PCA) on the resulting displacement vector fields. 3D fluoroscopic images are estimated by optimizing the resulting PCA coefficients iteratively through comparison of the cone-beam projections simulating kV treatment imaging and digitally reconstructed radiographs generated from the motion model. Patient and physical phantom datasets are used to evaluate the method in terms of tumor localization error compared to manually defined ground truth positions. Results: 4DCBCT-based motion models were derived and used to generate 3D fluoroscopic images at treatment time. For the patient datasets, the average tumor localization error and the 95th percentile were 1.57 and 3.13 respectively in subsets of four patient datasets. For the physical phantom datasets, the average tumor localization error and the 95th percentile were 1.14 and 2.78 respectively in two datasets. 4DCBCT motion models are shown to perform well in the context of generating 3D fluoroscopic images due to their ability to reproduce anatomical changes at treatment time. Conclusion: This study showed the feasibility of deriving 4DCBCT-based motion models and using them to generate 3D fluoroscopic images at treatment time in real clinical settings. 4DCBCT-based motion models were found to account for the 3D non-rigid motion of the patient anatomy during treatment and have the potential

  17. Measuring glomerular number from kidney MRI images

    NASA Astrophysics Data System (ADS)

    Thiagarajan, Jayaraman J.; Natesan Ramamurthy, Karthikeyan; Kanberoglu, Berkay; Frakes, David; Bennett, Kevin; Spanias, Andreas

    2016-03-01

    Measuring the glomerular number in the entire, intact kidney using non-destructive techniques is of immense importance in studying several renal and systemic diseases. Commonly used approaches either require destruction of the entire kidney or perform extrapolation from measurements obtained from a few isolated sections. A recent magnetic resonance imaging (MRI) method, based on the injection of a contrast agent (cationic ferritin), has been used to effectively identify glomerular regions in the kidney. In this work, we propose a robust, accurate, and low-complexity method for estimating the number of glomeruli from such kidney MRI images. The proposed technique has a training phase and a low-complexity testing phase. In the training phase, organ segmentation is performed on a few expert-marked training images, and glomerular and non-glomerular image patches are extracted. Using non-local sparse coding to compute similarity and dissimilarity graphs between the patches, the subspace in which the glomerular regions can be discriminated from the rest are estimated. For novel test images, the image patches extracted after pre-processing are embedded using the discriminative subspace projections. The testing phase is of low computational complexity since it involves only matrix multiplications, clustering, and simple morphological operations. Preliminary results with MRI data obtained from five kidneys of rats show that the proposed non-invasive, low-complexity approach performs comparably to conventional approaches such as acid maceration and stereology.

  18. Magnetic Resonance Imaging (MRI) Safety

    MedlinePlus

    ... by a receiver within the MR scanner. The signals are specially characterized using the rapidly changing magnetic field, and, with the help of computer processing, images of tissues are created as "slices" that ...

  19. Percutaneous Cervical Vertebroplasty in a MultifunctionalImage-Guided Therapy Suite: Hybrid Lateral Approach to C1 andC4 Under CT and Fluoroscopic Guidance

    SciTech Connect

    Huegli, R.W. Schaeren, S.; Jacob, A.L.; Martin, J.B.; Wetzel, S.G.

    2005-06-15

    A 76-year-old patient suffering from two painful osteolytic metastases in C1 and C4 underwent percutaneous vertebroplasty by a hybrid technique in a multi-functional image-guided therapy suite (MIGTS). Two trocars were first placed into the respective bodies of C1 and C4 under fluoroscopic computed tomography guidance using a lateral approach. Thereafter, the patient was transferred on a moving table to the digital subtraction angiography unit in the same room for implant injection. Good pain relief was achieved by this minimally invasive procedure without complications. A hybrid approach for vertebroplasty in a MIGTS appears to be safe and feasible and might be indicated in selected cases for difficult accessible lesions.

  20. Magnetic Resonance Imaging (MRI) (For Teens)

    MedlinePlus

    ... the MRI table. A specially trained technician (or "tech") operates the MRI machine. He or she may ... can't stay still during MRI. Sometimes MRI techs sedate teens who have trouble relaxing inside the ...

  1. Radiation injuries after fluoroscopic procedures.

    PubMed

    Mettler, Fred A; Koenig, Titus R; Wagner, Louis K; Kelsey, Charles A

    2002-10-01

    Fluoroscopically guided diagnostic and interventional procedures have become much more commonplace over the last decade. Current fluoroscopes are easily capable of producing dose rates in the range of 0.2 Gy (20 rads) per minute. The dose rate often changes dramatically with patient positioning and size. Most machines currently in use have no method to display approximate patient dose other than the rough surrogate of total fluoroscopy time. This does not include patient dose incurred during fluorography (serial imaging or cine runs), which can be considerably greater than dose during fluoroscopy. There have been over 100 cases of documented radiation skin and underlying tissue injury, a large portion of which resulted in dermal necrosis. The true number of injuries is undoubtedly much higher. The highest dose procedures are complex interventions such as those involving percutaneous angioplasties, stent placements, embolizations, and TIPS. In some cases skin doses have been in excess of 60 Gy (6000 rads). In many instances the procedures have been performed by physicians with little training in radiation effects, little appreciation of the radiation injuries that are possible or the strategies that could have been used to reduce both patient and staff doses. Almost all of the severe injuries that have occurred were avoidable.

  2. Target image search using fMRI signals

    NASA Astrophysics Data System (ADS)

    Xiong, Shi; Song, Sutao; Zhan, Yu; Zhang, Jiacai

    2014-03-01

    Recent neural signal decoding studies based on functional magnetic resonance imaging (fMRI) have identified the specific image presenting to the subject from a set of potential images, and some studies extend neural decoding into image reconstruction, i.e. image contents that the subject perceived were decoded from the fMRI signals recorded during the subject looking at images. In this paper, we decoded the target images using fMRI signals and described a target image searching method based on the relationship between target image stimuli and fMRI activity. We recorded fMRI data during a serial visual stimuli image presentation task, some of the stimuli images were target images and the rest images were non-target ones. Our fMRI data analysis results showed that in the serial visual presentation task, target images elicited a stereotypical response in the fMRI, which can be detected by multi-voxel pattern analysis (MVPA). Classifiers designed with support vector machine (SVM) used this response to decipher target images from non-target images. The leave-one-run-out cross-validation showed that we can pick out the target images with a possibility far above the chance level, which indicate that there's a neural signatures correlated with the target image recognition process in the human systems.

  3. Clinical image: MRI during migraine with aura

    SciTech Connect

    McNeal, A.C.

    1996-03-01

    Migraine refers to severe headaches that are usually unilateral, throbbing, and associated with nausea, vomiting, photophobia, and phonophobia. Migraine with aura (formerly called {open_quotes}classic migraine{close_quotes}) consists of the headache preceded or accompanied by neurological dysfunction. This dysfunction (aura) usually involves visual and sensory symptoms. The patient described herein experienced migraine with aura. MRI during and after the attack showed a reversible abnormality of the right posterior cerebral artery, with no parenchymal lesions. This appears to be the first report of abnormal MR vascular imaging during migraine with aura. 10 refs., 2 figs.

  4. Hemorrhage detection in MRI brain images using images features

    NASA Astrophysics Data System (ADS)

    Moraru, Luminita; Moldovanu, Simona; Bibicu, Dorin; Stratulat (Visan), Mirela

    2013-11-01

    The abnormalities appear frequently on Magnetic Resonance Images (MRI) of brain in elderly patients presenting either stroke or cognitive impairment. Detection of brain hemorrhage lesions in MRI is an important but very time-consuming task. This research aims to develop a method to extract brain tissue features from T2-weighted MR images of the brain using a selection of the most valuable texture features in order to discriminate between normal and affected areas of the brain. Due to textural similarity between normal and affected areas in brain MR images these operation are very challenging. A trauma may cause microstructural changes, which are not necessarily perceptible by visual inspection, but they could be detected by using a texture analysis. The proposed analysis is developed in five steps: i) in the pre-processing step: the de-noising operation is performed using the Daubechies wavelets; ii) the original images were transformed in image features using the first order descriptors; iii) the regions of interest (ROIs) were cropped from images feature following up the axial symmetry properties with respect to the mid - sagittal plan; iv) the variation in the measurement of features was quantified using the two descriptors of the co-occurrence matrix, namely energy and homogeneity; v) finally, the meaningful of the image features is analyzed by using the t-test method. P-value has been applied to the pair of features in order to measure they efficacy.

  5. 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

  6. A theoretical and experimental evaluation of the microangiographic fluoroscope: A high-resolution region-of-interest x-ray imager

    SciTech Connect

    Jain, Amit; Bednarek, D. R.; Ionita, Ciprian; Rudin, S.

    2011-07-15

    Purpose: The increasing need for better image quality and high spatial resolution for successful endovascular image-guided interventions (EIGIs) and the inherent limitations of the state-of-the-art detectors provide motivation to develop a detector system tailored to the specific, demanding requirements of neurointerventional applications.Method: A microangiographic fluoroscope (MAF) was developed to serve as a high-resolution, region-of-interest (ROI) x-ray imaging detector in conjunction with large lower-resolution full field-of-view (FOV) state-of-the-art x-ray detectors. The newly developed MAF is an indirect x-ray imaging detector capable of providing real-time images (30 frames per second) with high-resolution, high sensitivity, no lag and low instrumentation noise. It consists of a CCD camera coupled to a Gen 2 dual-stage microchannel plate light image intensifier (LII) through a fiber-optic taper. A 300 {mu}m thick CsI(Tl) phosphor serving as the front end is coupled to the LII. The LII is the key component of the MAF and the large variable gain provided by it enables the MAF to operate as a quantum-noise-limited detector for both fluoroscopy and angiography. Results: The linear cascade model was used to predict the theoretical performance of the MAF, and the theoretical prediction showed close agreement with experimental findings. Linear system metrics such as MTF and DQE were used to gauge the detector performance up to 10 cycles/mm. The measured zero frequency DQE(0) was 0.55 for an RQA5 spectrum. A total of 21 stages were identified for the whole imaging chain and each stage was characterized individually. Conclusions: The linear cascade model analysis provides insight into the imaging chain and may be useful for further development of the MAF detector. The preclinical testing of the prototype detector in animal procedures is showing encouraging results and points to the potential for significant impact on EIGIs when used in conjunction with a state

  7. Current Status of Hybrid PET/MRI in Oncologic Imaging

    PubMed Central

    Rosenkrantz, Andrew B.; Friedman, Kent; Chandarana, Hersh; Melsaether, Amy; Moy, Linda; Ding, Yu-Shin; Jhaveri, Komal; Beltran, Luis; Jain, Rajan

    2016-01-01

    OBJECTIVE This review article explores recent advancements in PET/MRI for clinical oncologic imaging. CONCLUSION Radiologists should understand the technical considerations that have made PET/MRI feasible within clinical workflows, the role of PET tracers for imaging various molecular targets in oncology, and advantages of hybrid PET/MRI compared with PET/CT. To facilitate this understanding, we discuss clinical examples (including gliomas, breast cancer, bone metastases, prostate cancer, bladder cancer, gynecologic malignancy, and lymphoma) as well as future directions, challenges, and areas for continued technical optimization for PET/MRI. PMID:26491894

  8. A new tool for benchmarking cardiovascular fluoroscopes.

    PubMed

    Balter, S; Heupler, F A; Lin, P J; Wondrow, M H

    2001-01-01

    This article reports the status of a new cardiovascular fluoroscopy benchmarking phantom. A joint working group of the Society for Cardiac Angiography and Interventions (SCA&I) and the National Electrical Manufacturers Association (NEMA) developed the phantom. The device was adopted as NEMA standard XR 21-2000, "Characteristics of and Test Procedures for a Phantom to Benchmark Cardiac Fluoroscopic and Photographic Performance," in August 2000. The test ensemble includes imaging field geometry, spatial resolution, low-contrast iodine detectability, working thickness range, visibility of moving targets, and phantom entrance dose. The phantom tests systems under conditions simulating normal clinical use for fluoroscopically guided invasive and interventional procedures. Test procedures rely on trained human observers.

  9. 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.

  10. Generation of fluoroscopic 3D images with a respiratory motion model based on an external surrogate signal.

    PubMed

    Hurwitz, Martina; Williams, Christopher L; Mishra, Pankaj; Rottmann, Joerg; Dhou, Salam; Wagar, Matthew; Mannarino, Edward G; Mak, Raymond H; Lewis, John H

    2015-01-21

    Respiratory motion during radiotherapy can cause uncertainties in definition of the target volume and in estimation of the dose delivered to the target and healthy tissue. In this paper, we generate volumetric images of the internal patient anatomy during treatment using only the motion of a surrogate signal. Pre-treatment four-dimensional CT imaging is used to create a patient-specific model correlating internal respiratory motion with the trajectory of an external surrogate placed on the chest. The performance of this model is assessed with digital and physical phantoms reproducing measured irregular patient breathing patterns. Ten patient breathing patterns are incorporated in a digital phantom. For each patient breathing pattern, the model is used to generate images over the course of thirty seconds. The tumor position predicted by the model is compared to ground truth information from the digital phantom. Over the ten patient breathing patterns, the average absolute error in the tumor centroid position predicted by the motion model is 1.4 mm. The corresponding error for one patient breathing pattern implemented in an anthropomorphic physical phantom was 0.6 mm. The global voxel intensity error was used to compare the full image to the ground truth and demonstrates good agreement between predicted and true images. The model also generates accurate predictions for breathing patterns with irregular phases or amplitudes.

  11. Generation of fluoroscopic 3D images with a respiratory motion model based on an external surrogate signal

    NASA Astrophysics Data System (ADS)

    Hurwitz, Martina; Williams, Christopher L.; Mishra, Pankaj; Rottmann, Joerg; Dhou, Salam; Wagar, Matthew; Mannarino, Edward G.; Mak, Raymond H.; Lewis, John H.

    2015-01-01

    Respiratory motion during radiotherapy can cause uncertainties in definition of the target volume and in estimation of the dose delivered to the target and healthy tissue. In this paper, we generate volumetric images of the internal patient anatomy during treatment using only the motion of a surrogate signal. Pre-treatment four-dimensional CT imaging is used to create a patient-specific model correlating internal respiratory motion with the trajectory of an external surrogate placed on the chest. The performance of this model is assessed with digital and physical phantoms reproducing measured irregular patient breathing patterns. Ten patient breathing patterns are incorporated in a digital phantom. For each patient breathing pattern, the model is used to generate images over the course of thirty seconds. The tumor position predicted by the model is compared to ground truth information from the digital phantom. Over the ten patient breathing patterns, the average absolute error in the tumor centroid position predicted by the motion model is 1.4 mm. The corresponding error for one patient breathing pattern implemented in an anthropomorphic physical phantom was 0.6 mm. The global voxel intensity error was used to compare the full image to the ground truth and demonstrates good agreement between predicted and true images. The model also generates accurate predictions for breathing patterns with irregular phases or amplitudes.

  12. Graphics processing unit (GPU) implementation of image processing algorithms to improve system performance of the control acquisition, processing, and image display system (CAPIDS) of the micro-angiographic fluoroscope (MAF)

    NASA Astrophysics Data System (ADS)

    Swetadri Vasan, S. N.; Ionita, Ciprian N.; Titus, A. H.; Cartwright, A. N.; Bednarek, D. R.; Rudin, S.

    2012-03-01

    We present the image processing upgrades implemented on a Graphics Processing Unit (GPU) in the Control, Acquisition, Processing, and Image Display System (CAPIDS) for the custom Micro-Angiographic Fluoroscope (MAF) detector. Most of the image processing currently implemented in the CAPIDS system is pixel independent; that is, the operation on each pixel is the same and the operation on one does not depend upon the result from the operation on the other, allowing the entire image to be processed in parallel. GPU hardware was developed for this kind of massive parallel processing implementation. Thus for an algorithm which has a high amount of parallelism, a GPU implementation is much faster than a CPU implementation. The image processing algorithm upgrades implemented on the CAPIDS system include flat field correction, temporal filtering, image subtraction, roadmap mask generation and display window and leveling. A comparison between the previous and the upgraded version of CAPIDS has been presented, to demonstrate how the improvement is achieved. By performing the image processing on a GPU, significant improvements (with respect to timing or frame rate) have been achieved, including stable operation of the system at 30 fps during a fluoroscopy run, a DSA run, a roadmap procedure and automatic image windowing and leveling during each frame.

  13. Graphics Processing Unit (GPU) implementation of image processing algorithms to improve system performance of the Control, Acquisition, Processing, and Image Display System (CAPIDS) of the Micro-Angiographic Fluoroscope (MAF).

    PubMed

    Vasan, S N Swetadri; Ionita, Ciprian N; Titus, A H; Cartwright, A N; Bednarek, D R; Rudin, S

    2012-02-23

    We present the image processing upgrades implemented on a Graphics Processing Unit (GPU) in the Control, Acquisition, Processing, and Image Display System (CAPIDS) for the custom Micro-Angiographic Fluoroscope (MAF) detector. Most of the image processing currently implemented in the CAPIDS system is pixel independent; that is, the operation on each pixel is the same and the operation on one does not depend upon the result from the operation on the other, allowing the entire image to be processed in parallel. GPU hardware was developed for this kind of massive parallel processing implementation. Thus for an algorithm which has a high amount of parallelism, a GPU implementation is much faster than a CPU implementation. The image processing algorithm upgrades implemented on the CAPIDS system include flat field correction, temporal filtering, image subtraction, roadmap mask generation and display window and leveling. A comparison between the previous and the upgraded version of CAPIDS has been presented, to demonstrate how the improvement is achieved. By performing the image processing on a GPU, significant improvements (with respect to timing or frame rate) have been achieved, including stable operation of the system at 30 fps during a fluoroscopy run, a DSA run, a roadmap procedure and automatic image windowing and leveling during each frame.

  14. SU-E-I-37: Low-Dose Real-Time Region-Of-Interest X-Ray Fluoroscopic Imaging with a GPU-Accelerated Spatially Different Bilateral Filtering

    SciTech Connect

    Chung, H; Lee, J; Pua, R; Cho, S; Jung, W

    2014-06-01

    Purpose: The purpose of our study is to reduce imaging radiation dose while maintaining image quality of region of interest (ROI) in X-ray fluoroscopy. A low-dose real-time ROI fluoroscopic imaging technique which includes graphics-processing-unit- (GPU-) accelerated image processing for brightness compensation and noise filtering was developed in this study. Methods: In our ROI fluoroscopic imaging, a copper filter is placed in front of the X-ray tube. The filter contains a round aperture to reduce radiation dose to outside of the aperture. To equalize the brightness difference between inner and outer ROI regions, brightness compensation was performed by use of a simple weighting method that applies selectively to the inner ROI, the outer ROI, and the boundary zone. A bilateral filtering was applied to the images to reduce relatively high noise in the outer ROI images. To speed up the calculation of our technique for real-time application, the GPU-acceleration was applied to the image processing algorithm. We performed a dosimetric measurement using an ion-chamber dosimeter to evaluate the amount of radiation dose reduction. The reduction of calculation time compared to a CPU-only computation was also measured, and the assessment of image quality in terms of image noise and spatial resolution was conducted. Results: More than 80% of dose was reduced by use of the ROI filter. The reduction rate depended on the thickness of the filter and the size of ROI aperture. The image noise outside the ROI was remarkably reduced by the bilateral filtering technique. The computation time for processing each frame image was reduced from 3.43 seconds with single CPU to 9.85 milliseconds with GPU-acceleration. Conclusion: The proposed technique for X-ray fluoroscopy can substantially reduce imaging radiation dose to the patient while maintaining image quality particularly in the ROI region in real-time.

  15. Fluoroscopic studies of the upper gastrointestinal tract: techniques and indications.

    PubMed

    Sánchez-Carpintero de la Vega, M; García Villar, C

    2017-01-25

    Fluoroscopic studies of the gastrointestinal tract are becoming increasing less common due to the introduction of other imaging techniques such as computed tomography and magnetic resonance imaging and to the increased availability of endoscopy. Nevertheless, fluoroscopic studies of the gastrointestinal tract continue to appear in clinical guidelines and some of their indications are still valid. These studies are dynamic, operator-dependent examinations that require training to obtain the maximum diagnostic performance. This review aims to describe the technique and bring the indications for this imaging modality up to date.

  16. Inert fluorinated gas MRI: a new pulmonary imaging modality.

    PubMed

    Couch, Marcus J; Ball, Iain K; Li, Tao; Fox, Matthew S; Ouriadov, Alexei V; Biman, Birubi; Albert, Mitchell S

    2014-12-01

    Fluorine-19 ((19)F) MRI of the lungs using inhaled inert fluorinated gases can potentially provide high quality images of the lungs that are similar in quality to those from hyperpolarized (HP) noble gas MRI. Inert fluorinated gases have the advantages of being nontoxic, abundant, and inexpensive compared with HP gases. Due to the high gyromagnetic ratio of (19)F, there is sufficient thermally polarized signal for imaging, and averaging within a single breath-hold is possible due to short longitudinal relaxation times. Therefore, the gases do not need to be hyperpolarized prior to their use in MRI. This eliminates the need for an expensive polarizer and expensive isotopes. Inert fluorinated gas MRI of the lungs has been previously demonstrated in animals, and more recently in healthy volunteers and patients with lung diseases. The ongoing improvements in image quality demonstrate the potential of (19)F MRI for visualizing the distribution of ventilation in human lungs and detecting functional biomarkers. In this brief review, the development of inert fluorinated gas MRI, current progress, and future prospects are discussed. The current state of HP noble gas MRI is also briefly discussed in order to provide context to the development of this new imaging modality. Overall, this may be a viable clinical imaging modality that can provide useful information for the diagnosis and management of chronic respiratory diseases.

  17. [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.

  18. TH-A-BRF-11: Image Intensity Non-Uniformities Between MRI Simulation and Diagnostic MRI

    SciTech Connect

    Paulson, E

    2014-06-15

    Purpose: MRI simulation for MRI-based radiotherapy demands that patients be setup in treatment position, which frequently involves use of alternative radiofrequency (RF) coil configurations to accommodate immobilized patients. However, alternative RF coil geometries may exacerbate image intensity non-uniformities (IINU) beyond those observed in diagnostic MRI, which may challenge image segmentation and registration accuracy as well as confound studies assessing radiotherapy response when MR simulation images are used as baselines for evaluation. The goal of this work was to determine whether differences in IINU exist between MR simulation and diagnostic MR images. Methods: ACR-MRI phantom images were acquired at 3T using a spin-echo sequence (TE/TR:20/500ms, rBW:62.5kHz, TH/skip:5/5mm). MR simulation images were obtained by wrapping two flexible phased-array RF coils around the phantom. Diagnostic MR images were obtained by placing the phantom into a commercial phased-array head coil. Pre-scan normalization was enabled in both cases. Images were transferred offline and corrected for IINU using the MNI N3 algorithm. Coefficients of variation (CV=σ/μ) were calculated for each slice. Wilcoxon matched-pairs and Mann-Whitney tests compared CV values between original and N3 images and between MR simulation and diagnostic MR images. Results: Significant differences in CV were detected between original and N3 images in both MRI simulation and diagnostic MRI groups (p=0.010, p=0.010). In addition, significant differences in CV were detected between original MR simulation and original and N3 diagnostic MR images (p=0.0256, p=0.0016). However, no significant differences in CV were detected between N3 MR simulation images and original or N3 diagnostic MR images, demonstrating the importance of correcting MR simulation images beyond pre-scan normalization prior to use in radiotherapy. Conclusions: Alternative RF coil configurations used in MRI simulation can Result in

  19. Effects of Image Contrast on Functional MRI Image Registration

    PubMed Central

    Gonzalez-Castillo, Javier; Duthie, Kristen N.; Saad, Ziad S.; Chu, Carlton; Bandettini, Peter A.; Luh, Wen-Ming

    2012-01-01

    Lack of tissue contrast and existing inhomogeneous bias fields from multi-channel coils have the potential to degrade the output of registration algorithms; and consequently degrade group analysis and any attempt to accurately localize brain function. Non-invasive ways to improve tissue contrast in fMRI images include the use of low flip angles (FAs) well below the Ernst angle and longer repetition times (TR). Techniques to correct intensity inhomogeneity are also available in most mainstream fMRI data analysis packages; but are not used as part of the pre-processing pipeline in many studies. In this work, we use a combination of real data and simulations to show that simple-to-implement acquisition/pre-processing techniques can significantly improve the outcome of both functional-to-functional and anatomical-to-functional image registrations. We also emphasize the need of tissue contrast on EPI images to be able to appropriately evaluate the quality of the alignment. In particular, we show that the use of low FAs (e.g., θ≤40°), when physiological noise considerations permit such an approach, significantly improves accuracy, consistency and stability of registration for data acquired at relatively short TRs (TR≤2s). Moreover, we also show that the application of bias correction techniques significantly improves alignment both for array-coil data (known to contain high intensity inhomogeneity) as well as birdcage-coil data. Finally, improvements in alignment derived from the use of the first infinite-TR volumes (ITVs) as targets for registration are also demonstrated. For the purpose of quantitatively evaluating the different scenarios, two novel metrics were developed: Mean Voxel Distance (MVD) to evaluate registration consistency, and Deviation of Mean Voxel Distance (dMVD) to evaluate registration stability across successive alignment attempts. PMID:23128074

  20. Magnetic Resonance Imaging (MRI): Brain (For Parents)

    MedlinePlus

    ... cause a problem near a strong magnetic field. Electronic devices aren't permitted in the MRI room. ... child may be given headphones to listen to music or earplugs to block the noise, and will ...

  1. Magnetic Resonance Imaging (MRI) (For Parents)

    MedlinePlus

    ... such as eyeglasses, jewelry, belts, or credit cards. Electronic devices are not permitted in the MRI room. ... child may be given headphones to listen to music or earplugs to block the noise and will ...

  2. Magnetic Resonance Imaging (MRI): Dynamic Pelvic Floor

    MedlinePlus

    ... noninvasive test that 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. Prostate cancer magnetic resonance imaging (MRI): multidisciplinary standpoint.

    PubMed

    Li, Liang; Wang, Liang; Feng, Zhaoyan; Hu, Zhiquan; Wang, Guoping; Yuan, Xianglin; Wang, He; Hu, Daoyu

    2013-04-01

    Prostate cancer is the most common cancer diagnosed in men and a leading cause of death. Accurate assessment is a prerequisite for optimal clinical management and therapy selection of prostate cancer. There are several parameters and nomograms to differentiate between patients with clinically insignificant disease and patients in need of treatment. Magnetic resonance imaging (MRI) is a technique which provides more detailed anatomical images due to high spatial resolution, superior contrast resolution, and multiplanar capability. State-of-the-art MRI techniques, such as diffusion weighted imaging (DWI), MR spectroscopic imaging (MRSI), dynamic contrast enhanced MRI (DCE-MRI), improve interpretation of prostate cancer imaging. In this article, we review the major role of MRI in the advanced management of prostate cancer to noninvasively improve tumor staging, biologic potential, treatment planning, therapy response, local recurrence, and to guide target biopsy for clinical suspected cancer with previous negative biopsy. Finally, future challenges and opportunities in prostate cancer management in the area of functional MRI are discussed as well.

  4. Implementation of a high-sensitivity Micro-Angiographic Fluoroscope (HS-MAF) for in-vivo endovascular image guided interventions (EIGI) and region-of-interest computed tomography (ROI-CT).

    PubMed

    Ionita, C N; Keleshis, C; Patel, V; Yadava, G; Hoffmann, K R; Bednarek, D R; Jain, A; Rudin, S

    2008-01-01

    New advances in catheter technology and remote actuation for minimally invasive procedures are continuously increasing the demand for better x-ray imaging technology. The new x-ray high-sensitivity Micro-Angiographic Fluoroscope (HS-MAF) detector offers high resolution and real-time image-guided capabilities which are unique when compared with commercially available detectors. This detector consists of a 300 μm CsI input phosphor coupled to a dual stage GEN2 micro-channel plate light image intensifier (LII), followed by minifying fiber-optic taper coupled to a CCD chip. The HS-MAF detector image array is 1024×1024 pixels, with a 12 bit depth capable of imaging at 30 frames per second. The detector has a round field of view with 4 cm diameter and 35 microns pixels. The LII has a large variable gain which allows usage of the detector at very low exposures characteristic of fluoroscopic ranges while maintaining very good image quality. The custom acquisition program allows real-time image display and data storage. We designed a set of in-vivo experimental interventions in which placement of specially designed endovascular stents were evaluated with the new detector and with a standard x-ray image intensifier (XII). Capabilities such fluoroscopy, angiography and ROI-CT reconstruction using rotational angiography data were implemented and verified. The images obtained during interventions under radiographic control with the HS-MAF detector were superior to those with the XII. In general, the device feature markers, the device structures, and the vessel geometry were better identified with the new detector. High-resolution detectors such as HS-MAF can vastly improve the accuracy of localization and tracking of devices such stents or catheters.

  5. Fusion of PET and MRI for Hybrid Imaging

    NASA Astrophysics Data System (ADS)

    Cho, Zang-Hee; Son, Young-Don; Kim, Young-Bo; Yoo, Seung-Schik

    Recently, the development of the fusion PET-MRI system has been actively studied to meet the increasing demand for integrated molecular and anatomical imaging. MRI can provide detailed anatomical information on the brain, such as the locations of gray and white matter, blood vessels, axonal tracts with high resolution, while PET can measure molecular and genetic information, such as glucose metabolism, neurotransmitter-neuroreceptor binding and affinity, protein-protein interactions, and gene trafficking among biological tissues. State-of-the-art MRI systems, such as the 7.0 T whole-body MRI, now can visualize super-fine structures including neuronal bundles in the pons, fine blood vessels (such as lenticulostriate arteries) without invasive contrast agents, in vivo hippocampal substructures, and substantia nigra with excellent image contrast. High-resolution PET, known as High-Resolution Research Tomograph (HRRT), is a brain-dedicated system capable of imaging minute changes of chemicals, such as neurotransmitters and -receptors, with high spatial resolution and sensitivity. The synergistic power of the two, i.e., ultra high-resolution anatomical information offered by a 7.0 T MRI system combined with the high-sensitivity molecular information offered by HRRT-PET, will significantly elevate the level of our current understanding of the human brain, one of the most delicate, complex, and mysterious biological organs. This chapter introduces MRI, PET, and PET-MRI fusion system, and its algorithms are discussed in detail.

  6. Initial tests of a prototype MRI-compatible PET imager

    NASA Astrophysics Data System (ADS)

    Raylman, Raymond R.; Majewski, Stan; Lemieux, Susan; Velan, S. Sendhil; Kross, Brain; Popov, Vladimir; Smith, Mark F.; Weisenberger, Andrew G.; Wojcik, Randy

    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 (a collaboration of West Virginia University and Jefferson Lab) is developing a system to acquire MRI and PET images contemporaneously. The prototype device consists of two opposed detector heads, operating in coincidence mode with an active FOV of 5×5×4 cm 3. Each MRI-PET detector module consists of an array of LSO detector elements (2.5×2.5×15 mm 3) coupled through a long fiber optic light guide to a single Hamamatsu flat panel PSPMT. The fiber optic light guide is made of a glued assembly of 2 mm diameter acrylic fibers with a total length of 2.5 m. The use of a light guides allows the PSPMTs to be positioned outside the bore of the 3 T General Electric MRI scanner used in the tests. Photon attenuation in the light guides resulted in an energy resolution of ˜60% FWHM, interaction of the magnetic field with PSPMT further reduced energy resolution to ˜85% FWHM. Despite this effect, excellent multi-plane PET and MRI images of a simple disk phantom were acquired simultaneously. Future work includes improved light guides, optimized magnetic shielding for the PSPMTs, construction of specialized coils to permit high-resolution MRI imaging, and use of the system to perform simultaneous PET and MRI or MR-spectroscopy .

  7. Restriction spectrum imaging improves MRI-based prostate cancer detection

    PubMed Central

    McCammack, Kevin C.; Schenker-Ahmed, Natalie M.; White, Nathan S.; Best, Shaun R.; Marks, Robert M.; Heimbigner, Jared; Kane, Christopher J.; Parsons, J. Kellogg; Kuperman, Joshua M.; Bartsch, Hauke; Desikan, Rahul S.; Rakow-Penner, Rebecca A.; Liss, Michael A.; Margolis, Daniel J. A.; Raman, Steven S.; Shabaik, Ahmed; Dale, Anders M.; Karow, David S.

    2017-01-01

    Purpose To compare the diagnostic performance of restriction spectrum imaging (RSI), with that of conventional multi-parametric (MP) magnetic resonance imaging (MRI) for prostate cancer (PCa) detection in a blinded reader-based format. Methods Three readers independently evaluated 100 patients (67 with proven PCa) who underwent MP-MRI and RSI within 6 months of systematic biopsy (N = 67; 23 with targeting performed) or prostatectomy (N = 33). Imaging was performed at 3 Tesla using a phased-array coil. Readers used a five-point scale estimating the likelihood of PCa present in each prostate sextant. Evaluation was performed in two separate sessions, first using conventional MP-MRI alone then immediately with MP-MRI and RSI in the same session. Four weeks later, another scoring session used RSI and T2-weighted imaging (T2WI) without conventional diffusion-weighted or dynamic contrast-enhanced imaging. Reader interpretations were then compared to prostatectomy data or biopsy results. Receiver operating characteristic curves were performed, with area under the curve (AUC) used to compare across groups. Results MP-MRI with RSI achieved higher AUCs compared to MP-MRI alone for identifying high-grade (Gleason score greater than or equal to 4 + 3=7) PCa (0.78 vs. 0.70 at the sextant level; P < 0.001 and 0.85 vs. 0.79 at the hemigland level; P = 0.04). RSI and T2WI alone achieved AUCs similar to MP-MRI for high-grade PCa (0.71 vs. 0.70 at the sextant level). With hemigland analysis, high-grade disease results were similar when comparing RSI + T2WI with MP-MRI, although with greater AUCs compared to the sextant analysis (0.80 vs. 0.79). Conclusion Including RSI with MP-MRI improves PCa detection compared to MP-MRI alone, and RSI with T2WI achieves similar PCa detection as MP-MRI. PMID:26910114

  8. PCA-based groupwise image registration for quantitative MRI.

    PubMed

    Huizinga, W; Poot, D H J; Guyader, J-M; Klaassen, R; Coolen, B F; van Kranenburg, M; van Geuns, R J M; Uitterdijk, A; Polfliet, M; Vandemeulebroucke, J; Leemans, A; Niessen, W J; Klein, S

    2016-04-01

    Quantitative magnetic resonance imaging (qMRI) is a technique for estimating quantitative tissue properties, such as the T1 and T2 relaxation times, apparent diffusion coefficient (ADC), and various perfusion measures. This estimation is achieved by acquiring multiple images with different acquisition parameters (or at multiple time points after injection of a contrast agent) and by fitting a qMRI signal model to the image intensities. Image registration is often necessary to compensate for misalignments due to subject motion and/or geometric distortions caused by the acquisition. However, large differences in image appearance make accurate image registration challenging. In this work, we propose a groupwise image registration method for compensating misalignment in qMRI. The groupwise formulation of the method eliminates the requirement of choosing a reference image, thus avoiding a registration bias. The method minimizes a cost function that is based on principal component analysis (PCA), exploiting the fact that intensity changes in qMRI can be described by a low-dimensional signal model, but not requiring knowledge on the specific acquisition model. The method was evaluated on 4D CT data of the lungs, and both real and synthetic images of five different qMRI applications: T1 mapping in a porcine heart, combined T1 and T2 mapping in carotid arteries, ADC mapping in the abdomen, diffusion tensor mapping in the brain, and dynamic contrast-enhanced mapping in the abdomen. Each application is based on a different acquisition model. The method is compared to a mutual information-based pairwise registration method and four other state-of-the-art groupwise registration methods. Registration accuracy is evaluated in terms of the precision of the estimated qMRI parameters, overlap of segmented structures, distance between corresponding landmarks, and smoothness of the deformation. In all qMRI applications the proposed method performed better than or equally well as

  9. Functionality and operation of fluoroscopic automatic brightness control/automatic dose rate control logic in modern cardiovascular and interventional angiography systems: A Report of Task Group 125 Radiography/Fluoroscopy Subcommittee, Imaging Physics Committee, Science Council

    SciTech Connect

    Rauch, Phillip; Lin, Pei-Jan Paul; Balter, Stephen; Fukuda, Atsushi; Goode, Allen; Hartwell, Gary; LaFrance, Terry; Nickoloff, Edward; Shepard, Jeff; Strauss, Keith

    2012-05-15

    Task Group 125 (TG 125) was charged with investigating the functionality of fluoroscopic automatic dose rate and image quality control logic in modern angiographic systems, paying specific attention to the spectral shaping filters and variations in the selected radiologic imaging parameters. The task group was also charged with describing the operational aspects of the imaging equipment for the purpose of assisting the clinical medical physicist with clinical set-up and performance evaluation. Although there are clear distinctions between the fluoroscopic operation of an angiographic system and its acquisition modes (digital cine, digital angiography, digital subtraction angiography, etc.), the scope of this work was limited to the fluoroscopic operation of the systems studied. The use of spectral shaping filters in cardiovascular and interventional angiography equipment has been shown to reduce patient dose. If the imaging control algorithm were programmed to work in conjunction with the selected spectral filter, and if the generator parameters were optimized for the selected filter, then image quality could also be improved. Although assessment of image quality was not included as part of this report, it was recognized that for fluoroscopic imaging the parameters that influence radiation output, differential absorption, and patient dose are also the same parameters that influence image quality. Therefore, this report will utilize the terminology ''automatic dose rate and image quality'' (ADRIQ) when describing the control logic in modern interventional angiographic systems and, where relevant, will describe the influence of controlled parameters on the subsequent image quality. A total of 22 angiography units were investigated by the task group and of these one each was chosen as representative of the equipment manufactured by GE Healthcare, Philips Medical Systems, Shimadzu Medical USA, and Siemens Medical Systems. All equipment, for which measurement data were

  10. Functionality and operation of fluoroscopic automatic brightness control/automatic dose rate control logic in modern cardiovascular and interventional angiography systems: a report of Task Group 125 Radiography/Fluoroscopy Subcommittee, Imaging Physics Committee, Science Council.

    PubMed

    Rauch, Phillip; Lin, Pei-Jan Paul; Balter, Stephen; Fukuda, Atsushi; Goode, Allen; Hartwell, Gary; LaFrance, Terry; Nickoloff, Edward; Shepard, Jeff; Strauss, Keith

    2012-05-01

    Task Group 125 (TG 125) was charged with investigating the functionality of fluoroscopic automatic dose rate and image quality control logic in modern angiographic systems, paying specific attention to the spectral shaping filters and variations in the selected radiologic imaging parameters. The task group was also charged with describing the operational aspects of the imaging equipment for the purpose of assisting the clinical medical physicist with clinical set-up and performance evaluation. Although there are clear distinctions between the fluoroscopic operation of an angiographic system and its acquisition modes (digital cine, digital angiography, digital subtraction angiography, etc.), the scope of this work was limited to the fluoroscopic operation of the systems studied. The use of spectral shaping filters in cardiovascular and interventional angiography equipment has been shown to reduce patient dose. If the imaging control algorithm were programmed to work in conjunction with the selected spectral filter, and if the generator parameters were optimized for the selected filter, then image quality could also be improved. Although assessment of image quality was not included as part of this report, it was recognized that for fluoroscopic imaging the parameters that influence radiation output, differential absorption, and patient dose are also the same parameters that influence image quality. Therefore, this report will utilize the terminology "automatic dose rate and image quality" (ADRIQ) when describing the control logic in modern interventional angiographic systems and, where relevant, will describe the influence of controlled parameters on the subsequent image quality. A total of 22 angiography units were investigated by the task group and of these one each was chosen as representative of the equipment manufactured by GE Healthcare, Philips Medical Systems, Shimadzu Medical USA, and Siemens Medical Systems. All equipment, for which measurement data were

  11. Molecular Imaging with MRI: Potential Application in Pancreatic Cancer

    PubMed Central

    Chen, Chen; Wu, Chang Qiang; Chen, Tian Wu; Tang, Meng Yue; Zhang, Xiao Ming

    2015-01-01

    Despite the variety of approaches that have been improved to achieve a good understanding of pancreatic cancer (PC), the prognosis of PC remains poor, and the survival rates are dismal. The lack of early detection and effective interventions is the main reason. Therefore, considerable ongoing efforts aimed at identifying early PC are currently being pursued using a variety of methods. In recent years, the development of molecular imaging has made the specific targeting of PC in the early stage possible. Molecular imaging seeks to directly visualize, characterize, and measure biological processes at the molecular and cellular levels. Among different imaging technologies, the magnetic resonance (MR) molecular imaging has potential in this regard because it facilitates noninvasive, target-specific imaging of PC. This topic is reviewed in terms of the contrast agents for MR molecular imaging, the biomarkers related to PC, targeted molecular probes for MRI, and the application of MRI in the diagnosis of PC. PMID:26579537

  12. Clinical applications of magnetic resonance imaging (MRI) of the heart

    SciTech Connect

    Westcott, J.L.; Steiner, R.M.

    1986-01-01

    The rapid progress of MRI has been remarkable, and it is clear that it will become an important method for cardiac imaging. Its major advantages are the lack of ionizing radiation and the ability to obtain excellent global images of the cardiac walls and chambers without the need for contrast injection or cardiac catheterization. High resolution surface coil imaging, tissue spectroscopy, and other improvements and applications should be rapidly forthcoming.

  13. The physics of functional magnetic resonance imaging (fMRI)

    PubMed Central

    Buxton, Richard B

    2015-01-01

    Functional magnetic resonance imaging (fMRI) is a methodology for detecting dynamic patterns of activity in the working human brain. Although the initial discoveries that led to fMRI are only about 20 years old, this new field has revolutionized the study of brain function. The ability to detect changes in brain activity has a biophysical basis in the magnetic properties of deoxyhemoglobin, and a physiological basis in the way blood flow increases more than oxygen metabolism when local neural activity increases. These effects translate to a subtle increase in the local magnetic resonance signal, the blood oxygenation level dependent (BOLD) effect, when neural activity increases. With current techniques, this pattern of activation can be measured with resolution approaching 1 mm3 spatially and 1 s temporally. This review focuses on the physical basis of the BOLD effect, the imaging methods used to measure it, the possible origins of the physiological effects that produce a mismatch of blood flow and oxygen metabolism during neural activation, and the mathematical models that have been developed to understand the measured signals. An overarching theme is the growing field of quantitative fMRI, in which other MRI methods are combined with BOLD methods and analyzed within a theoretical modeling framework to derive quantitative estimates of oxygen metabolism and other physiological variables. That goal is the current challenge for fMRI: to move fMRI from a mapping tool to a quantitative probe of brain physiology. PMID:24006360

  14. MRI and PET image fusion using fuzzy logic and image local features.

    PubMed

    Javed, Umer; Riaz, Muhammad Mohsin; Ghafoor, Abdul; Ali, Syed Sohaib; Cheema, Tanveer Ahmed

    2014-01-01

    An image fusion technique for magnetic resonance imaging (MRI) and positron emission tomography (PET) using local features and fuzzy logic is presented. The aim of proposed technique is to maximally combine useful information present in MRI and PET images. Image local features are extracted and combined with fuzzy logic to compute weights for each pixel. Simulation results show that the proposed scheme produces significantly better results compared to state-of-art schemes.

  15. Prostate MRI for brachytherapists: Diagnosis, imaging pitfalls, and post-therapy assessment.

    PubMed

    Venkatesan, A M; Stafford, R J; Duran, C; Soni, P D; Berlin, A; McLaughlin, P W

    2017-01-27

    Optimal integration of multiparametric MRI (mp MRI) into prostate brachytherapy practice necessitates an understanding of imaging findings pertinent to prostate cancer detection and staging. This review will summarize prostate cancer imaging findings and tumor staging on mp MRI, including an overview of the Prostate Imaging Reporting and Data System (PIRADS)-structured reporting schema, mp MRI findings observed in the post-therapy setting including cases of post-treatment recurrence, and MRI concepts integral to successful salvage brachytherapy.

  16. Magnetic resonance imaging (MRI): A review of genetic damage investigations.

    PubMed

    Vijayalaxmi; Fatahi, Mahsa; Speck, Oliver

    2015-01-01

    Magnetic resonance imaging (MRI) is a powerful, non-invasive diagnostic medical imaging technique widely used to acquire detailed information about anatomy and function of different organs in the body, in both health and disease. It utilizes electromagnetic fields of three different frequency bands: static magnetic field (SMF), time-varying gradient magnetic fields (GMF) in the kHz range and pulsed radiofrequency fields (RF) in the MHz range. There have been some investigations examining the extent of genetic damage following exposure of bacterial and human cells to all three frequency bands of electromagnetic fields, as used during MRI: the rationale for these studies is the well documented evidence of positive correlation between significantly increased genetic damage and carcinogenesis. Overall, the published data were not sufficiently informative and useful because of the small sample size, inappropriate comparison of experimental groups, etc. Besides, when an increased damage was observed in MRI-exposed cells, the fate of such lesions was not further explored from multiple 'down-stream' events. This review provides: (i) information on the basic principles used in MRI technology, (ii) detailed experimental protocols, results and critical comments on the genetic damage investigations thus far conducted using MRI equipment and, (iii) a discussion on several gaps in knowledge in the current scientific literature on MRI. Comprehensive, international, multi-centered collaborative studies, using a common and widely used MRI exposure protocol (cardiac or brain scan) incorporating several genetic/epigenetic damage end-points as well as epidemiological investigations, in large number of individuals/patients are warranted to reduce and perhaps, eliminate uncertainties raised in genetic damage investigations in cells exposed in vitro and in vivo to MRI.

  17. Breast imaging with ultrasound tomography: a comparative study with MRI

    NASA Astrophysics Data System (ADS)

    Ranger, Bryan; Littrup, Peter; Duric, Neb; Li, Cuiping; Schmidt, Steven; Lupinacci, Jessica; Myc, Lukasz; Szczepanski, Amy; Rama, Olsi; Bey-Knight, Lisa

    2010-03-01

    The purpose of this study was to investigate the performance of an ultrasound tomography (UST) prototype relative to magnetic resonance (MR) for imaging overall breast anatomy and accentuating tumors relative to background tissue. The study was HIPAA compliant, approved by the Institutional Review Board, and performed after obtaining the requisite informed consent. Twenty-three patients were imaged with MR and the UST prototype. T1 weighted images with fat saturation, with and without gadolinium enhancement, were used to examine anatomical structures and tumors, while T2 weighted images were used to identify cysts. The UST scans generated sound speed, attenuation, and reflection images. A qualitative visual comparison of the MRI and UST images was then used to identify anatomical similarities. A more focused approach that involved a comparison of reported masses, lesion volumes, and breast density was used to quantify the findings from the visual assessment. Our acoustic tomography prototype imaged distributions of fibrous stroma, parenchyma, fatty tissues, and lesions in patterns similar to those seen in the MR images. The range of thresholds required to establish tumor volume equivalency between MRI and UST suggested that a universal threshold for isolating masses relative to background tissue is feasible with UST. UST has demonstrated the ability to visualize and characterize breast tissues in a manner comparable to MRI. Thresholding techniques accentuate masses relative to background anatomy, which may prove clinically useful for early cancer detection.

  18. Opening the black box: imaging nanoparticle transport with MRI

    NASA Astrophysics Data System (ADS)

    Phoenix, V.; Holmes, W. M.

    2009-12-01

    While most renown for its use in medicine, magnetic resonance imaging (MRI) has tremendous potential in the study of environmental processes. Its ability to non-invasively image inside materials that are opaque to other imaging methods (in particular light based techniques) is a particular strength. MRI has already been used, for example, to study fluid flow in rocks and image mass transport and biogeochemical processes in biofilms [1-4]. Here, we report of the use of MRI to image nanoparticle transport through porous geologic media (in this case packed gravel columns). Packed column experiments are key to understanding nanoparticulate transport in porous geologic media. Whilst highly informative, the data obtained can be a bulk average of a complex and heterogeneous array of interactions within the column. Natural environmental systems are often complex, displaying heterogeneity in geometry, hydrodynamics, geochemistry and microbiology throughout. MRI enables us to quantify better how this heterogeneity may influence nanoparticle transport and fate by enabling us to look inside the column and image the movement of nanoparticles within. To make the nanoparticle readily visible to MRI, it is labelled with a paramagnetic tag (commonly gadolinium). Indeed, a wide variety of off-the-shelf paramagnetically tagged nanoparticles and macromolecules are available, each with different properties enabling us to explore the impact of particle charge, size etc on their transport behaviour. In this preliminary study, packed columns of quartz or marble based gravels (approx 5 mm diameter) were first imaged to check their suitability for MR imaging. This was done as geologic material can contain sufficiently high concentrations of ferro- and paramagnetic ions to induce unwanted artefacts in the MR image. All gravels imaged (Rose quartz, Creswick quartz gravel and Ben Deulin white marble) produced minimal or no artefacts. A solution of the nanoparticle GadoCELLTrack (BioPAL), was

  19. Magnetic Particle Imaging (MPI) for NMR and MRI researchers

    NASA Astrophysics Data System (ADS)

    Saritas, Emine U.; Goodwill, Patrick W.; Croft, Laura R.; Konkle, Justin J.; Lu, Kuan; Zheng, Bo; Conolly, Steven M.

    2013-04-01

    Magnetic Particle Imaging (MPI) is a new tracer imaging modality that is gaining significant interest from NMR and MRI researchers. While the physics of MPI differ substantially from MRI, it employs hardware and imaging concepts that are familiar to MRI researchers, such as magnetic excitation and detection, pulse sequences, and relaxation effects. Furthermore, MPI employs the same superparamagnetic iron oxide (SPIO) contrast agents that are sometimes used for MR angiography and are often used for MRI cell tracking studies. These SPIOs are much safer for humans than iodine or gadolinium, especially for Chronic Kidney Disease (CKD) patients. The weak kidneys of CKD patients cannot safely excrete iodine or gadolinium, leading to increased morbidity and mortality after iodinated X-ray or CT angiograms, or after gadolinium-MRA studies. Iron oxides, on the other hand, are processed in the liver, and have been shown to be safe even for CKD patients. Unlike the “black blood” contrast generated by SPIOs in MRI due to increased T2∗ dephasing, SPIOs in MPI generate positive, “bright blood” contrast. With this ideal contrast, even prototype MPI scanners can already achieve fast, high-sensitivity, and high-contrast angiograms with millimeter-scale resolutions in phantoms and in animals. Moreover, MPI shows great potential for an exciting array of applications, including stem cell tracking in vivo, first-pass contrast studies to diagnose or stage cancer, and inflammation imaging in vivo. So far, only a handful of prototype small-animal MPI scanners have been constructed worldwide. Hence, MPI is open to great advances, especially in hardware, pulse sequence, and nanoparticle improvements, with the potential to revolutionize the biomedical imaging field.

  20. Integration of kerma-area product and cumulative air kerma determination into a skin dose tracking system for fluoroscopic imaging procedures

    NASA Astrophysics Data System (ADS)

    Vijayan, Sarath; Shankar, Alok; Rudin, Stephen; Bednarek, Daniel R.

    2016-03-01

    The skin dose tracking system (DTS) that we developed provides a color-coded mapping of the cumulative skin dose distribution on a 3D graphic of the patient during fluoroscopic procedures in real time. The DTS has now been modified to also calculate the kerma area product (KAP) and cumulative air kerma (CAK) for fluoroscopic interventions using data obtained in real-time from the digital bus on a Toshiba Infinix system. KAP is the integral of air kerma over the beam area and is typically measured with a large-area transmission ionization chamber incorporated into the collimator assembly. In this software, KAP is automatically determined for each x-ray pulse as the product of the air kerma/ mAs from a calibration file for the given kVp and beam filtration times the mAs per pulse times the length and width of the beam times a field nonuniformity correction factor. Field nonuniformity is primarily the result of the heel effect and the correction factor was determined from the beam profile measured using radio-chromic film. Dividing the KAP by the beam area at the interventional reference point provides the area averaged CAK. The KAP and CAK per x-ray pulse are summed after each pulse to obtain the total procedure values in real-time. The calculated KAP and CAK were compared to the values displayed by the fluoroscopy machine with excellent agreement. The DTS now is able to automatically calculate both KAP and CAK without the need for measurement by an add-on transmission ionization chamber.

  1. New insights on COPD imaging via CT and MRI

    PubMed Central

    Sverzellati, N; Molinari, F; Pirronti, T; Bonomo, L; Spagnolo, P; Zompatori, M

    2007-01-01

    Multidetector-row computed tomography (MDCT) can be used to quantify morphological features and investigate structure/function relationship in COPD. This approach allows a phenotypical definition of COPD patients, and might improve our understanding of disease pathogenesis and suggest new therapeutical options. In recent years, magnetic resonance imaging (MRI) has also become potentially suitable for the assessment of ventilation, perfusion and respiratory mechanics. This review focuses on the established clinical applications of CT, and novel CT and MRI techniques, which may prove valuable in evaluating the structural and functional damage in COPD. PMID:18229568

  2. 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

  3. MRI Image Processing Based on Fractal Analysis

    PubMed

    Marusina, Mariya Y; Mochalina, Alexandra P; Frolova, Ekaterina P; Satikov, Valentin I; Barchuk, Anton A; Kuznetcov, Vladimir I; Gaidukov, Vadim S; Tarakanov, Segrey A

    2017-01-01

    Background: Cancer is one of the most common causes of human mortality, with about 14 million new cases and 8.2 million deaths reported in in 2012. Early diagnosis of cancer through screening allows interventions to reduce mortality. Fractal analysis of medical images may be useful for this purpose. Materials and Methods: In this study, we examined magnetic resonance (MR) images of healthy livers and livers containing metastases from colorectal cancer. The fractal dimension and the Hurst exponent were chosen as diagnostic features for tomographic imaging using Image J software package for image processings FracLac for applied for fractal analysis with a 120x150 pixel area. Calculations of the fractal dimensions of pathological and healthy tissue samples were performed using the box-counting method. Results: In pathological cases (foci formation), the Hurst exponent was less than 0.5 (the region of unstable statistical characteristics). For healthy tissue, the Hurst index is greater than 0.5 (the zone of stable characteristics). Conclusions: The study indicated the possibility of employing fractal rapid analysis for the detection of focal lesions of the liver. The Hurst exponent can be used as an important diagnostic characteristic for analysis of medical images.

  4. Imaging tumour motion for radiotherapy planning using MRI

    PubMed Central

    Kauczor, Hans-Ulrich; Plathow, Christian

    2006-01-01

    Novel technology has made dynamic magnetic resonance imaging (MRI) of lung motion and lung tumour mobility during continuous respiration feasible. This might be beneficial for planning of radiotherapy of lung tumours, especially when using high precision techniques. This paper describes the recent developments to analyze and visualize pulmonary nodules during continuous respiration using MRI. Besides recent dynamic two-dimensional approaches to quantify motion of pulmonary nodules during respiration novel three-dimensional techniques are presented. Beyond good correlation to pulmonary function tests MRI also provides regional information about differences between tumour-bearing and non-tumour bearing lung and the restrictive effects of radiotherapy as well as the compensation by the contralateral lung. PMID:17114068

  5. The role of susceptibility weighted imaging in functional MRI.

    PubMed

    Haacke, E Mark; Ye, Yongquan

    2012-08-15

    The development of functional brain magnetic resonance imaging (fMRI) has been a boon for neuroscientists and radiologists alike. It provides for fundamental information on brain function and better diagnostic tools to study disease. In this paper, we will review some of the early concepts in high resolution gradient echo imaging with a particular emphasis on susceptibility weighted imaging (SWI) and MR angiography (MRA). We begin with the history of our own experience in this area, followed by a discussion of the role of high resolution in studying the vasculature of the brain and how this relates to the BOLD (blood oxygenation level dependent) signal. We introduce the role of SWI and susceptibility mapping (SWIM) in fMRI and close with recommendations for future high resolution experiments.

  6. [Brain development of infant and MRI by diffusion tensor imaging].

    PubMed

    Dubois, J; Dehaene-Lambertz, G; Mangin, J-F; Le Bihan, D; Hüppi, P S; Hertz-Pannier, L

    2012-01-01

    Studying how the brain develops and becomes functional is important to understand how the man has been able to develop specific cognitive abilities, and to comprehend the complexity of some developmental pathologies. Thanks to magnetic resonance imaging (MRI), it is now possible to image the baby's immature brain and to consider subtle correlations between the brain anatomical development and the early acquisition of cognitive functions. Dedicated methodologies for image acquisition and post-treatment must then be used because the size of cerebral structures and the image contrast are very different in comparison with the adult brain, and because the examination length is a major constraint. Two recent studies have evaluated the developing brain under an original perspective. The first one has focused on cortical folding in preterm newborns, from 6 to 8 months of gestational age, assessed with T2-weighted conventional MRI. The second study has mapped the organization and maturation of white matter fiber bundles in 1- to 4-month-old healthy infants with diffusion tensor imaging (DTI). Both studies have enabled to highlight spatio-temporal differences in the brain regions' maturation, as well as early anatomical asymmetries between cerebral hemispheres. These studies emphasize the potential of MRI to evaluate brain development compared with the infant's psychomotor acquisitions after birth.

  7. Development and evaluation of a new radiographic and fluoroscopic imager based on electron-multiplying CCDs: The solid state x-ray image intensifier

    NASA Astrophysics Data System (ADS)

    Kuhls-Gilcrist, Andrew Thomas

    A new dual detector system was developed which utilizes a low resolution, large field-of-view x-ray image intensifier (II) and a high resolution, region-of-interest microangiographic (MA) detector on the same c-arm gantry. With this new MA-II system, the larger field-of-view (FOV) II can be operated when the demands of the task are not as high, and a larger imaging area is desired. However, when a higher-resolution image with greater image quality is desired at a targeted region-of-interest (ROI), the MA can be deployed to take on these greater demands. To quantitatively and qualitatively assess the imaging performance of each detector under realistic conditions, angiographic images of simulated vessels and rabbit neurovasculature were acquired with both detectors under nearly identical conditions. With the MA detector deployed, vessels as small as 95 mum were visible, whereas the II could not detect vessels smaller than 235 mum. The ROI MA mode was also shown to provide sharper images with higher contrast-to-noise ratios and was four times as likely to successfully detect overlapping vessels as compared to the II. More accurate three-dimensional center lines of vasculature using multi-view reconstruction techniques were also obtained with the MA. The solid state x-ray image intensifier (SSXII) was developed to provide similar high-resolution imaging capabilities as the MA and a built in adjustable gain to provide high-sensitivity imaging capabilities for operation at all exposures used in medical x-ray imaging procedures. The imaging components used in construction of the prototype SSXII were selected based on a theoretical performance evaluation, using a Fourier-based linear-systems model analysis. The performance of the prototype SSXII was then extensively evaluated. Images of various objects and image comparisons with current state-of-the-art detectors qualitatively demonstrated that the SSXII is capable of providing substantial improvements. A quantitative

  8. Linking MRI Postprocessing with Magnetic Source Imaging in MRI-negative Epilepsy

    PubMed Central

    Wang, Zhong I.; Alexopoulos, Andreas V.; Jones, Stephen E.; Najm, Imad M.; Ristic, Aleksandar; Wong, Chong; Prayson, Richard; Schneider, Felix; Kakisaka, Yosuke; Wang, Shuang; Bingaman, William; Gonzalez-Martinez, Jorge A.; Burgess, Richard C.

    2015-01-01

    Objective MRI-negative (MRI–) pharmacoresistant focal epilepsy (PFE) patients are most challenging for epilepsy surgical management. This study utilizes a voxel-based MRI postprocessing technique, implemented using a morphometric analysis program (MAP), aiming to facilitate detection of subtle focal cortical dysplasia (FCD) in MRI– patients. Furthermore, the study examines the concordance between MAP-identified regions and localization from magnetic source imaging (MSI). Methods Included in this retrospective study were 25 MRI– surgical patients. MAP was performed on T1-weighted MRI, with comparison to a normal database. The pertinence of MAP+ areas was confirmed by MSI, surgical outcome and pathology. Analyses of MAP and MSI were performed blindly from patients' clinical information and independently from each other. Results The detection rate of subtle changes by MAP was 48% (12/25). Once MAP+ areas were resected, patients were more likely to be seizure-free (p = 0.02). There were no false positives in the 25 age-matched normal controls. Seven patients had a concordant MSI correlate. Patients in whom a concordant area was identified by both MAP and MSI had a significantly higher chance of achieving a seizure-free outcome following complete resection of this area (p = 0.008). In the 9 resected MAP+ areas, pathology revealed FCD type IA in 7 and type IIB in 2. Interpretation MAP shows promise in identifying subtle FCD abnormalities and increasing the diagnostic yield of conventional MRI visual analysis in presurgical evaluation of PFE. Concordant MRI postprocessing and MSI analyses may lead to the noninvasive identification of a structurally and electrically abnormal subtle lesion that can be surgically targeted. PMID:24777960

  9. Renal compartment segmentation in DCE-MRI images.

    PubMed

    Yang, Xin; Le Minh, Hung; Tim Cheng, Kwang-Ting; Sung, Kyung Hyun; Liu, Wenyu

    2016-08-01

    Renal compartment segmentation from Dynamic Contrast-Enhanced MRI (DCE-MRI) images is an important task for functional kidney evaluation. Despite advancement in segmentation methods, most of them focus on segmenting an entire kidney on CT images, there still lacks effective and automatic solutions for accurate segmentation of internal renal structures (i.e. cortex, medulla and renal pelvis) from DCE-MRI images. In this paper, we introduce a method for renal compartment segmentation which can robustly achieve high segmentation accuracy for a wide range of DCE-MRI data, and meanwhile requires little manual operations and parameter settings. The proposed method consists of five main steps. First, we pre-process the image time series to reduce the motion artifacts caused by the movement of the patients during the scans and enhance the kidney regions. Second, the kidney is segmented as a whole based on the concept of Maximally Stable Temporal Volume (MSTV). The proposed MSTV detects anatomical structures that are homogeneous in the spatial domain and stable in terms of temporal dynamics. MSTV-based kidney segmentation is robust to noises and does not require a training phase. It can well adapt to kidney shape variations caused by renal dysfunction. Third, voxels in the segmented kidney are described by principal components (PCs) to remove temporal redundancy and noises. And then k-means clustering of PCs is applied to separate voxels into multiple clusters. Fourth, the clusters are automatically labeled as cortex, medulla and pelvis based on voxels' geometric locations and intensity distribution. Finally, an iterative refinement method is introduced to further remove noises in each segmented compartment. Experiments on 14 real clinical kidney datasets and 12 synthetic dataset demonstrate that results produced by our method match very well with those segmented manually and the performance of our method is superior to the other five existing methods.

  10. Complete fourier direct magnetic resonance imaging (CFD-MRI) for diffusion MRI

    PubMed Central

    Özcan, Alpay

    2013-01-01

    The foundation for an accurate and unifying Fourier-based theory of diffusion weighted magnetic resonance imaging (DW–MRI) is constructed by carefully re-examining the first principles of DW–MRI signal formation and deriving its mathematical model from scratch. The derivations are specifically obtained for DW–MRI signal by including all of its elements (e.g., imaging gradients) using complex values. Particle methods are utilized in contrast to conventional partial differential equations approach. The signal is shown to be the Fourier transform of the joint distribution of number of the magnetic moments (at a given location at the initial time) and magnetic moment displacement integrals. In effect, the k-space is augmented by three more dimensions, corresponding to the frequency variables dual to displacement integral vectors. The joint distribution function is recovered by applying the Fourier transform to the complete high-dimensional data set. In the process, to obtain a physically meaningful real valued distribution function, phase corrections are applied for the re-establishment of Hermitian symmetry in the signal. Consequently, the method is fully unconstrained and directly presents the distribution of displacement integrals without any assumptions such as symmetry or Markovian property. The joint distribution function is visualized with isosurfaces, which describe the displacement integrals, overlaid on the distribution map of the number of magnetic moments with low mobility. The model provides an accurate description of the molecular motion measurements via DW–MRI. The improvement of the characterization of tissue microstructure leads to a better localization, detection and assessment of biological properties such as white matter integrity. The results are demonstrated on the experimental data obtained from an ex vivo baboon brain. PMID:23596401

  11. Photo-magnetic Imaging: Resolving Optical Contrast at MRI resolution

    PubMed Central

    Lin, Yuting; Gao, Hao; Thayer, David; Luk, Alex L.; Gulsen, Gultekin

    2014-01-01

    In this paper, we establish the mathematical framework of a novel imaging technique, namely Photo-magnetic Imaging (PMI). PMI uses laser to illuminate biological tissues and measure the induced temperature variations using magnetic resonance imaging (MRI). PMI overcomes the limitation of conventional optical imaging and allows imaging of optical contrast at MRI spatial resolution. The image reconstruction for PMI, using a finite element-based algorithm with iterative approach, is presented in this paper. The quantitative accuracy of PMI is investigated for various inclusion sizes, depths and absorption values. Then, a comparison between conventional Diffuse Optical Tomography (DOT) and PMI is carried out to illustrate the superior performance of PMI. An example is presented showing that two 2 mm diameter inclusions embedded 4.5 mm deep and located side by side in a 25 mm diameter circular geometry medium is recovered as a single 6 mm diameter object with DOT. However, these two objects are not only effectively resolved with PMI, but their true concentration are also recovered successfully. PMID:23640084

  12. Functional MRI studies of human vision on a clinical imager

    SciTech Connect

    George, J.S.; Lewine, J.D.; Aine, C.J.; van Hulsteyn, D.; Wood, C.C.; Sanders, J.; Maclin, E.; Belliveau, J.W.; Caprihan, A.

    1992-09-01

    During the past decade, Magnetic Resonance Imaging (MRI) has become the method of choice for imaging the anatomy of the human brain. Recently, Belliveau and colleagues have reported the use of echo planar magnetic resonance imaging (EPI) to image patterns of neural activity. Here, we report functional MR imaging in response to visual stimulation without the use of contrast agents, and without the extensive hardware modifications required for EPI. Regions of activity were observed near the expected locations of V1, V2 and possibly V3 and another active region was observed near the parietal-occipital sulcus on the superior surface of the cerebrum. These locations are consistent with sources observed in neuromagnetic studies of the human visual response.

  13. Functional MRI studies of human vision on a clinical imager

    SciTech Connect

    George, J.S.; Lewine, J.D.; Aine, C.J.; van Hulsteyn, D.; Wood, C.C. ); Sanders, J.; Maclin, E. ); Belliveau, J.W. ); Caprihan, A. )

    1992-01-01

    During the past decade, Magnetic Resonance Imaging (MRI) has become the method of choice for imaging the anatomy of the human brain. Recently, Belliveau and colleagues have reported the use of echo planar magnetic resonance imaging (EPI) to image patterns of neural activity. Here, we report functional MR imaging in response to visual stimulation without the use of contrast agents, and without the extensive hardware modifications required for EPI. Regions of activity were observed near the expected locations of V1, V2 and possibly V3 and another active region was observed near the parietal-occipital sulcus on the superior surface of the cerebrum. These locations are consistent with sources observed in neuromagnetic studies of the human visual response.

  14. Adaptive image guided brachytherapy for cervical cancer: A combined MRI-/CT-planning technique with MRI only at first fraction

    PubMed Central

    Nesvacil, Nicole; Pötter, Richard; Sturdza, Alina; Hegazy, Neamat; Federico, Mario; Kirisits, Christian

    2013-01-01

    Purpose To investigate and test the feasibility of adaptive 3D image based BT planning for cervix cancer patients in settings with limited access to MRI, using a combination of MRI for the first BT fraction and planning of subsequent fractions on CT. Material and methods For 20 patients treated with EBRT and HDR BT with tandem/ring applicators two sets of treatment plans were compared. Scenario one is based on the “gold standard” with individual MRI-based treatment plans (applicator reconstruction, target contouring and dose optimization) for two BT applications with two fractions each. Scenario two is based on one initial MRI acquisition with an applicator in place for the planning of the two fractions of the first BT application and reuse of the target contour delineated on MRI for subsequent planning of the second application on CT. Transfer of the target from MRI of the first application to the CT of the second one was accomplished by use of an automatic applicator-based image registration procedure. Individual dose optimization of the second BT application was based on the transferred MRI target volume and OAR structures delineated on CT. DVH parameters were calculated for transferred target structures (virtual dose from MRI/CT plan) and CT-based OAR. The quality of the MRI/CT combination method was investigated by evaluating the CT-based dose distributions on MRI-based target and OAR contours of the same application (real dose from MRI/CT plan). Results The mean difference between the MRI based target volumes (HR CTVMRI2) and the structures transferred from MRI to CT (HR CTVCT2) was −1.7 ± 6.6 cm3 (−2.9 ± 20.4%) with a median of −0.7 cm3. The mean difference between the virtual and the real total D90, based on the MRI/CT combination technique was −1.5 ± 4.3 Gy EQD2. This indicates a small systematic underestimation of the real D90. Conclusions A combination of MRI for first fraction and subsequent CT based planning is feasible and easy

  15. In vivo prostate cancer detection and grading using restriction spectrum imaging-MRI

    PubMed Central

    McCammack, KC; Kane, CJ; Parsons, JK; White, NS; Schenker-Ahmed, NM; Kuperman, JM; Bartsch, H; Desikan, RS; Rakow-Penner, RA; Adams, D; Liss, MA; Mattrey, RF; Bradley, WG; Margolis, DJA; Raman, SS; Shabaik, A; Dale, AM; Karow, DS

    2017-01-01

    BACKGROUND Magnetic resonance imaging (MRI) is emerging as a robust, noninvasive method for detecting and characterizing prostate cancer (PCa), but limitations remain in its ability to distinguish cancerous from non-cancerous tissue. We evaluated the performance of a novel MRI technique, restriction spectrum imaging (RSI-MRI), to quantitatively detect and grade PCa compared with current standard-of-care MRI. METHODS In a retrospective evaluation of 33 patients with biopsy-proven PCa who underwent RSI-MRI and standard MRI before radical prostatectomy, receiver-operating characteristic (ROC) curves were performed for RSI-MRI and each quantitative MRI term, with area under the ROC curve (AUC) used to compare each term’s ability to differentiate between PCa and normal prostate. Spearman rank-order correlations were performed to assess each term’s ability to predict PCa grade in the radical prostatectomy specimens. RESULTS RSI-MRI demonstrated superior differentiation of PCa from normal tissue, with AUC of 0.94 and 0.85 for RSI-MRI and conventional diffusion MRI, respectively (P = 0.04). RSI-MRI also demonstrated superior performance in predicting PCa aggressiveness, with Spearman rank-order correlation coefficients of 0.53 (P = 0.002) and − 0.42 (P = 0.01) for RSI-MRI and conventional diffusion MRI, respectively, with tumor grade. CONCLUSIONS RSI-MRI significantly improves upon current noninvasive PCa imaging and may potentially enhance its diagnosis and characterization. PMID:26754261

  16. A new paramagnetically shifted imaging probe for MRI

    PubMed Central

    Senanayake, P. Kanthi; Rogers, Nicola J.; Finney, Katie‐Louise N.A.; Harvey, Peter; Funk, Alexander M.; Wilson, J. Ian; O'Hogain, Dara; Maxwell, Ross; Parker, David

    2016-01-01

    Purpose To develop and characterize a new paramagnetic contrast agent for molecular imaging by MRI. Methods A contrast agent was developed for direct MRI detection through the paramagnetically shifted proton magnetic resonances of two chemically equivalent tert‐butyl reporter groups within a dysprosium(III) complex. The complex was characterized in phantoms and imaged in physiologically intact mice at 7 Tesla (T) using three‐dimensional (3D) gradient echo and spectroscopic imaging (MRSI) sequences to measure spatial distribution and signal frequency. Results The reporter protons reside ∼6.5 Å from the paramagnetic center, resulting in fast T 1 relaxation (T 1 = 8 ms) and a large paramagnetic frequency shift exceeding 60 ppm. Fast relaxation allowed short scan repetition times with high excitation flip angle, resulting in high sensitivity. The large dipolar shift allowed direct frequency selective excitation and acquisition of the dysprosium(III) complex, independent of the tissue water signal. The biokinetics of the complex were followed in vivo with a temporal resolution of 62 s following a single, low‐dose intravenous injection. The lower concentration limit for detection was ∼23 μM. Through MRSI, the temperature dependence of the paramagnetic shift (0.28 ppm.K−1) was exploited to examine tissue temperature variation. Conclusions These data demonstrate a new MRI agent with the potential for physiological monitoring by MRI. Magn Reson Med 77:1307–1317, 2017. © 2016 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:26922918

  17. Diffeomorphic Image Registration of Diffusion MRI Using Spherical Harmonics

    PubMed Central

    Geng, Xiujuan; Ross, Thomas J.; Gu, Hong; Shin, Wanyong; Zhan, Wang; Chao, Yi-Ping; Lin, Ching-Po; Schuff, Norbert; Yang, Yihong

    2013-01-01

    Non-rigid registration of diffusion MRI is crucial for group analyses and building white matter and fiber tract atlases. Most current diffusion MRI registration techniques are limited to the alignment of diffusion tensor imaging (DTI) data. We propose a novel diffeomorphic registration method for high angular resolution diffusion images by mapping their orientation distribution functions (ODFs). ODFs can be reconstructed using q-ball imaging (QBI) techniques and represented by spherical harmonics (SHs) to resolve intra-voxel fiber crossings. The registration is based on optimizing a diffeomorphic demons cost function. Unlike scalar images, deforming ODF maps requires ODF reorientation to maintain its consistency with the local fiber orientations. Our method simultaneously reorients the ODFs by computing a Wigner rotation matrix at each voxel, and applies it to the SH coefficients during registration. Rotation of the coefficients avoids the estimation of principal directions, which has no analytical solution and is time consuming. The proposed method was validated on both simulated and real data sets with various metrics, which include the distance between the estimated and simulated transformation fields, the standard deviation of the general fractional anisotropy and the directional consistency of the deformed and reference images. The registration performance using SHs with different maximum orders were compared using these metrics. Results show that the diffeomorphic registration improved the affine alignment, and registration using SHs with higher order SHs further improved the registration accuracy by reducing the shape difference and improving the directional consistency of the registered and reference ODF maps. PMID:21134814

  18. Whole-Body MRI in Children: Current Imaging Techniques and Clinical Applications

    PubMed Central

    2015-01-01

    Whole-body magnetic resonance imaging (MRI) is increasingly used in children to evaluate the extent and distribution of various neoplastic and non-neoplastic diseases. Not using ionizing radiation is a major advantage of pediatric whole-body MRI. Coronal and sagittal short tau inversion recovery imaging is most commonly used as the fundamental whole-body MRI protocol. Diffusion-weighted imaging and Dixon-based imaging, which has been recently incorporated into whole-body MRI, are promising pulse sequences, particularly for pediatric oncology. Other pulse sequences may be added to increase diagnostic capability of whole-body MRI. Of importance, the overall whole-body MRI examination time should be less than 30-60 minutes in children, regardless of the imaging protocol. Established and potentially useful clinical applications of pediatric whole-body MRI are described. PMID:26355493

  19. Validation of the hypercapnic calibrated fMRI method using DOT-fMRI fusion imaging

    PubMed Central

    Yücel, Meryem A.; Evans, Karleyton C.; Selb, Juliette; Huppert, Theodore J.; Boas, David A.; Gagnon, Louis

    2014-01-01

    Calibrated functional Magnetic Resonance Imaging (fMRI) is a widely used method to investigate brain function in terms of physiological quantities such as the cerebral metabolic rate of oxygen (CMRO2). The first and one of the most common methods of fMRI calibration is hypercapnic calibration. This is achieved via simultaneous measures of blood-oxygenation-level dependent (BOLD) and the arterial spin labeling (ASL) signals during a functional task that evokes regional changes in CMRO2. A subsequent acquisition is then required during which the subject inhales carbon dioxide for short periods of time. A calibration constant, typically labeled M, is then estimated from the hypercapnic data and is subsequently used together with the BOLD-ASL recordings to compute evoked changes in CMRO2 during the functional task. The computation of M assumes a constant CMRO2 during the CO2 inhalation, an assumption that has been questioned since the origin of calibrated fMRI. In this study we used Diffuse Optical Tomography (DOT) together with BOLD and ASL – an alternative calibration method that does not require any gas manipulation and therefore no constant CMRO2 assumption - to cross-validate the estimation of M obtained from a traditional hypercapnic calibration. We found a high correlation between the M values (R=0.87, p<0.01) estimated using these two approaches. The findings serve to validate the hypercapnic fMRI calibration technique and suggest that the inter-subject variability routinely obtained for M is reproducible with an alternative method and might therefore reflect inter-subject physiological variability. PMID:25196509

  20. Current status of magnetic resonance imaging (MRI) and ultrasonography fusion software platforms for guidance of prostate biopsies.

    PubMed

    Logan, Jennifer K; Rais-Bahrami, Soroush; Turkbey, Baris; Gomella, Andrew; Amalou, Hayet; Choyke, Peter L; Wood, Bradford J; Pinto, Peter A

    2014-11-01

    Prostate MRI is currently the best diagnostic imaging method for detecting PCa. Magnetic resonance imaging (MRI)/ultrasonography (US) fusion allows the sensitivity and specificity of MRI to be combined with the real-time capabilities of transrectal ultrasonography (TRUS). Multiple approaches and techniques exist for MRI/US fusion and include direct 'in bore' MRI biopsies, cognitive fusion, and MRI/US fusion via software-based image coregistration platforms.

  1. Ultrafast inverse imaging techniques for fMRI.

    PubMed

    Lin, Fa-Hsuan; Tsai, Kevin W K; Chu, Ying-Hua; Witzel, Thomas; Nummenmaa, Aapo; Raij, Tommi; Ahveninen, Jyrki; Kuo, Wen-Jui; Belliveau, John W

    2012-08-15

    Inverse imaging (InI) supercharges the sampling rate of traditional functional MRI 10-100 fold at a cost of a moderate reduction in spatial resolution. The technique is inspired by similarities between multi-sensor magnetoencephalography (MEG) and highly parallel radio-frequency (RF) MRI detector arrays. Using presently available 32-channel head coils at 3T, InI can be sampled at 10 Hz and provides about 5-mm cortical spatial resolution with whole-brain coverage. Here we discuss the present applications of InI, as well as potential future challenges and opportunities in further improving its spatiotemporal resolution and sensitivity. InI may become a helpful tool for clinicians and neuroscientists for revealing the complex dynamics of brain functions during task-related and resting states.

  2. Image quality transfer and applications in diffusion MRI.

    PubMed

    Alexander, Daniel C; Zikic, Darko; Ghosh, Aurobrata; Tanno, Ryutaro; Wottschel, Viktor; Zhang, Jiaying; Kaden, Enrico; Dyrby, Tim B; Sotiropoulos, Stamatios N; Zhang, Hui; Criminisi, Antonio

    2017-03-03

    This paper introduces a new computational imaging technique called image quality transfer (IQT). IQT uses machine learning to transfer the rich information available from one-off experimental medical imaging devices to the abundant but lower-quality data from routine acquisitions. The procedure uses matched pairs to learn mappings from low-quality to corresponding high-quality images. Once learned, these mappings then augment unseen low quality images, for example by enhancing image resolution or information content. Here, we demonstrate IQT using a simple patch-regression implementation and the uniquely rich diffusion MRI data set from the human connectome project (HCP). Results highlight potential benefits of IQT in both brain connectivity mapping and microstructure imaging. In brain connectivity mapping, IQT reveals, from standard data sets, thin connection pathways that tractography normally requires specialised data to reconstruct. In microstructure imaging, IQT shows potential in estimating, from standard "single-shell" data (one non-zero b-value), maps of microstructural parameters that normally require specialised multi-shell data. Further experiments show strong generalisability, highlighting IQT's benefits even when the training set does not directly represent the application domain. The concept extends naturally to many other imaging modalities and reconstruction problems.

  3. Multispectral optoacoustic and MRI coregistration for molecular imaging of orthotopic model of human glioblastoma.

    PubMed

    Attia, Amalina Binte Ebrahim; Ho, Chris Jun Hui; Chandrasekharan, Prashant; Balasundaram, Ghayathri; Tay, Hui Chien; Burton, Neal C; Chuang, Kai-Hsiang; Ntziachristos, Vasilis; Olivo, Malini

    2016-07-01

    Multi-modality imaging methods are of great importance in oncologic studies for acquiring complementary information, enhancing the efficacy in tumor detection and characterization. We hereby demonstrate a hybrid non-invasive in vivo imaging approach of utilizing magnetic resonance imaging (MRI) and Multispectral Optoacoustic Tomography (MSOT) for molecular imaging of glucose uptake in an orthotopic glioblastoma in mouse. The molecular and functional information from MSOT can be overlaid on MRI anatomy via image coregistration to provide insights into probe uptake in the brain, which is verified by ex vivo fluorescence imaging and histological validation. In vivo MSOT and MRI imaging of an orthotopic glioma mouse model injected with IRDye800-2DG. Image coregistration between MSOT and MRI enables multifaceted (anatomical, functional, molecular) information from MSOT to be overlaid on MRI anatomy images to derive tumor physiological parameters such as perfusion, haemoglobin and oxygenation.

  4. A paramagnetic CEST agent for imaging glucose by MRI.

    PubMed

    Zhang, Shanrong; Trokowski, Robert; Sherry, A Dean

    2003-12-17

    The europium(III) complex of a DOTA-tetraamide ligand (DOTA = 1,4,7,10-tetraazacyclododecane-N,N',N' ',N' ''-tetraacetic acids) containing two phenyl boronate pendent arms binds glucose reversibly with an association constant of 383 M-1 at pH 7. Glucose binding results in slowing of water exchange between a single Eu(III)-bound water molecule and bulk water, and this can be imaged by MRI using chemical exchange saturation transfer (CEST) imaging sequence. This metabolite-responsive paramagnetic CEST agent responds to changes in glucose over the physiologically important range (0-20 mM), and thus it offers the possibility of high-sensitivity MR imaging glucose in tissues using bulk water protons as antenna.

  5. CNS Animal fMRI imaging in Pain and Analgesia

    PubMed Central

    Borsook, David; Becerra, Lino

    2010-01-01

    Animal imaging of brain systems offers exciting opportunities to better understand the neurobiology of pain and analgesia. Overall functional studies have lagged behind human studies as a result of technical issues including the use of anesthesia. Now that many of these issues have been overcome including the possibility of imaging awake animals, there are new opportunities to study whole brain systems neurobiology of acute and chronic pain as well as analgesic effects on brain systems de novo (using pharmacological MRI) or testing in animal models of pain. Understanding brain networks in these areas may provide new insights into translational science, and use neural networks as a “language of translation” between preclinical to clinical models. In this review we evaluate the role of functional and anatomical imaging in furthering our understanding in pain and analgesia. PMID:21126534

  6. Brain Tumor Segmentation Using Convolutional Neural Networks in MRI Images.

    PubMed

    Pereira, Sergio; Pinto, Adriano; Alves, Victor; Silva, Carlos A

    2016-05-01

    Among brain tumors, gliomas are the most common and aggressive, leading to a very short life expectancy in their highest grade. Thus, treatment planning is a key stage to improve the quality of life of oncological patients. Magnetic resonance imaging (MRI) is a widely used imaging technique to assess these tumors, but the large amount of data produced by MRI prevents manual segmentation in a reasonable time, limiting the use of precise quantitative measurements in the clinical practice. So, automatic and reliable segmentation methods are required; however, the large spatial and structural variability among brain tumors make automatic segmentation a challenging problem. In this paper, we propose an automatic segmentation method based on Convolutional Neural Networks (CNN), exploring small 3 ×3 kernels. The use of small kernels allows designing a deeper architecture, besides having a positive effect against overfitting, given the fewer number of weights in the network. We also investigated the use of intensity normalization as a pre-processing step, which though not common in CNN-based segmentation methods, proved together with data augmentation to be very effective for brain tumor segmentation in MRI images. Our proposal was validated in the Brain Tumor Segmentation Challenge 2013 database (BRATS 2013), obtaining simultaneously the first position for the complete, core, and enhancing regions in Dice Similarity Coefficient metric (0.88, 0.83, 0.77) for the Challenge data set. Also, it obtained the overall first position by the online evaluation platform. We also participated in the on-site BRATS 2015 Challenge using the same model, obtaining the second place, with Dice Similarity Coefficient metric of 0.78, 0.65, and 0.75 for the complete, core, and enhancing regions, respectively.

  7. Brain Tumor Segmentation using Convolutional Neural Networks in MRI Images.

    PubMed

    Pereira, Sergio; Pinto, Adriano; Alves, Victor; Silva, Carlos A

    2016-03-04

    Among brain tumors, gliomas are the most common and aggressive, leading to a very short life expectancy in their highest grade. Thus, treatment planning is a key stage to improve the quality of life of oncological patients. Magnetic Resonance Imaging (MRI) is a widely used imaging technique to assess these tumors, but the large amount of data produced by MRI prevents manual segmentation in a reasonable time, limiting the use of precise quantitative measurements in the clinical practice. So, automatic and reliable segmentation methods are required; however, the large spatial and structural variability among brain tumors make automatic segmentation a challenging problem. In this paper, we propose an automatic segmentation method based on Convolutional Neural Networks (CNN), exploring small 33 kernels. The use of small kernels allows designing a deeper architecture, besides having a positive effect against overfitting, given the fewer number of weights in the network. We also investigated the use of intensity normalization as a pre-processing step, which though not common in CNN-based segmentation methods, proved together with data augmentation to be very effective for brain tumor segmentation in MRI images. Our proposal was validated in the Brain Tumor Segmentation Challenge 2013 database (BRATS 2013), obtaining simultaneously the first position for the complete, core, and enhancing regions in Dice Similarity Coefficient metric (0:88, 0:83, 0:77) for the Challenge data set. Also, it obtained the overall first position by the online evaluation platform. We also participated in the on-site BRATS 2015 Challenge using the same model, obtaining the second place, with Dice Similarity Coefficient metric of 0:78, 0:65, and 0:75 for the complete, core, and enhancing regions, respectively.

  8. Imaging of juvenile idiopathic arthritis. Part II: Ultrasonography and MRI

    PubMed Central

    Grochowska, Elżbieta; Gietka, Piotr; Płaza, Mateusz; Pracoń, Grzegorz; Saied, Fadhil; Walentowska-Janowicz, Marta

    2016-01-01

    Juvenile idiopathic arthritis is the most common autoimmune systemic disease of the connective tissue affecting individuals in the developmental age. Radiography, which was described in the first part of this publication, is the standard modality in the assessment of this condition. Ultrasound and magnetic resonance imaging enable early detection of the disease which affects soft tissues, as well as bones. Ultrasound assessment involves: joint cavities, tendon sheaths and bursae for the presence of synovitis, intraand extraarticular fat tissue to visualize signs of inflammation, hyaline cartilage, cartilaginous epiphysis and subchondral bone to detect cysts and erosions, and ligaments, tendons and their entheses for signs of enthesopathies and tendinopathies. Magnetic resonance imaging is indicated in children with juvenile idiopathic arthritis for assessment of inflammation in peripheral joints, tendon sheaths and bursae, bone marrow involvement and identification of inflammatory lesions in whole-body MRI, particularly when the clinical picture is unclear. Also, MRI of the spine and spinal cord is used in order to diagnose synovial joint inflammation, bone marrow edema and spondylodiscitis as well as to assess their activity, location, and complications (spinal canal stenosis, subluxation, e.g. in the atlantoaxial region). This article discusses typical pathological changes seen on ultrasound and magnetic resonance imaging. The role of these two methods for disease monitoring, its identification in the pre-clinical stage and establishing its remission are also highlighted. PMID:27679727

  9. The Efficiency of Diffusion Weighted MRI and MR Spectroscopy On Breast MR Imaging

    PubMed Central

    Altay, Canan; Balcı, Pınar

    2014-01-01

    The main purpose of breast magnetic resonance imaging (MRI) in radiologically routine is to establish an imaging protocol that will create high quality images with a short period of time. Fort this purpose, an imaging protocol should include a conventional breast MRI and contrast enhanced sequences. Proton MR spectroscopy (MRS) and diffusion weighted imaging (DWI) are important MR techniques for evaluation to complicated breast lesions. In this article, we will evaluate that technical properties of the MRS and DWI as additional MR imaging.

  10. Management of pediatric radiation dose using GE fluoroscopic equipment.

    PubMed

    Belanger, Barry; Boudry, John

    2006-09-01

    In this article, we present GE Healthcare's design philosophy and implementation of X-ray imaging systems with dose management for pediatric patients, as embodied in its current radiography and fluoroscopy and interventional cardiovascular X-ray product offerings. First, we present a basic framework of image quality and dose in the context of a cost-benefit trade-off, with the development of the concept of imaging dose efficiency. A set of key metrics of image quality and dose efficiency is presented, including X-ray source efficiency, detector quantum efficiency (DQE), detector dynamic range, and temporal response, with an explanation of the clinical relevance of each. Second, we present design methods for automatically selecting optimal X-ray technique parameters (kVp, mA, pulse width, and spectral filtration) in real time for various clinical applications. These methods are based on an optimization scheme where patient skin dose is minimized for a target desired image contrast-to-noise ratio. Operator display of skin dose and Dose-Area Product (DAP) is covered, as well. Third, system controls and predefined protocols available to the operator are explained in the context of dose management and the need to meet varying clinical procedure imaging demands. For example, fluoroscopic dose rate is adjustable over a range of 20:1 to adapt to different procedure requirements. Fourth, we discuss the impact of image processing techniques upon dose minimization. In particular, two such techniques, dynamic range compression through adaptive multiband spectral filtering and fluoroscopic noise reduction, are explored in some detail. Fifth, we review a list of system dose-reduction features, including automatic spectral filtration, virtual collimation, variable-rate pulsed fluoroscopic, grid and no-grid techniques, and fluoroscopic loop replay with store. In addition, we describe a new feature that automatically minimizes the patient-to-detector distance, along with an

  11. Imaging mouse lung allograft rejection with 1H MRI

    PubMed Central

    Guo, Jinbang; Huang, Howard J.; Wang, Xingan; Wang, Wei; Ellison, Henry; Thomen, Robert P.; Gelman, Andrew E.; Woods, Jason C.

    2014-01-01

    Purpose To demonstrate that longitudinal, non-invasive monitoring via MRI can characterize acute cellular rejection (ACR) in mouse orthotopic lung allografts. Methods Nineteen Balb/c donor to C57BL/6 recipient orthotopic left lung transplants were performed, further divided into control-Ig vs anti-CD4/anti-CD8 treated groups. A two-dimensional multi-slice gradient-echo pulse sequence synchronized with ventilation was used on a small-animal MR scanner to acquire proton images of lung at post-operative days 3, 7 and 14, just before sacrifice. Lung volume and parenchymal signal were measured, and lung compliance was calculated as volume change per pressure difference between high and low pressures. Results Normalized parenchymal signal in the control-Ig allograft increased over time, with statistical significance between day 14 and day 3 post transplantation (0.046→0.789, P < 0.05), despite large inter-mouse variations; this was consistent with histopathologic evidence of rejection. Compliance of the control-Ig allograft decreased significantly over time (0.013→0.003, P < 0.05), but remained constant in mice treated with anti-CD4/anti-CD8 antibodies. Conclusion Lung allograft rejection in individual mice can be monitored by lung parenchymal signal changes and by lung compliance through MRI. Longitudinal imaging can help us better understand the time course of individual lung allograft rejection and response to treatment. PMID:24954886

  12. Automated quantification of lumbar vertebral kinematics from dynamic fluoroscopic sequences

    NASA Astrophysics Data System (ADS)

    Camp, Jon; Zhao, Kristin; Morel, Etienne; White, Dan; Magnuson, Dixon; Gay, Ralph; An, Kai-Nan; Robb, Richard

    2009-02-01

    We hypothesize that the vertebra-to-vertebra patterns of spinal flexion and extension motion of persons with lower back pain will differ from those of persons who are pain-free. Thus, it is our goal to measure the motion of individual lumbar vertebrae noninvasively from dynamic fluoroscopic sequences. Two-dimensional normalized mutual information-based image registration was used to track frame-to-frame motion. Software was developed that required the operator to identify each vertebra on the first frame of the sequence using a four-point "caliper" placed at the posterior and anterior edges of the inferior and superior end plates of the target vertebrae. The program then resolved the individual motions of each vertebra independently throughout the entire sequence. To validate the technique, 6 cadaveric lumbar spine specimens were potted in polymethylmethacrylate and instrumented with optoelectric sensors. The specimens were then placed in a custom dynamic spine simulator and moved through flexion-extension cycles while kinematic data and fluoroscopic sequences were simultaneously acquired. We found strong correlation between the absolute flexionextension range of motion of each vertebra as recorded by the optoelectric system and as determined from the fluoroscopic sequence via registration. We conclude that this method is a viable way of noninvasively assessing twodimensional vertebral motion.

  13. Elasticity reconstructive imaging by means of stimulated echo MRI.

    PubMed

    Chenevert, T L; Skovoroda, A R; O'Donnell, M; Emelianov, S Y

    1998-03-01

    A method is introduced to measure internal mechanical displacement and strain by means of MRI. Such measurements are needed to reconstruct an image of the elastic Young's modulus. A stimulated echo acquisition sequence with additional gradient pulses encodes internal displacements in response to an externally applied differential deformation. The sequence provides an accurate measure of static displacement by limiting the mechanical transitions to the mixing period of the simulated echo. Elasticity reconstruction involves definition of a region of interest having uniform Young's modulus along its boundary and subsequent solution of the discretized elasticity equilibrium equations. Data acquisition and reconstruction were performed on a urethane rubber phantom of known elastic properties and an ex vivo canine kidney phantom using <2% differential deformation. Regional elastic properties are well represented on Young's modulus images. The long-term objective of this work is to provide a means for remote palpation and elasticity quantitation in deep tissues otherwise inaccessible to manual palpation.

  14. Imaging Modality of Choice for Pre-Operative Cochlear Imaging: HRCT vs. MRI Temporal Bone

    PubMed Central

    Solanki, Rajendra N.; Shah, Dipali C.; Vishwakarma, Rajesh; Kumar, Sandeep

    2016-01-01

    Introduction Congenital inner ear malformations occur as a result of the arrest or aberrance of inner ear development due to the heredity, gene mutation or other factors. Ever since the availability of cochlear implants, pre-operative evaluation by imaging of temporal bone has gained much attention. Precise selection of the candidate for cochlear implant dependent on preoperative radiological investigations. Only CT (Computed Tomography) and MRI (Magnetic Resonance Imaging) can provide a better picture of anatomy and pathology. Aim To compare pre-operative imaging findings of both MRI and High Resolution Computed Tomography (HRCT) temporal bone and to find the best modality of choice in patients with bilateral profound Sensorineural Hearing Loss (SNHL). Materials and Methods This was a prospective, longitudinal, observational study conducted between June 2010 to November 2012. A total of 144 temporal bones were evaluated in 72 children with bilateral profound SNHL with congenital inner ear malformations. Each temporal bone was considered as a single case (144 cases). All the patients underwent HRCT and high field MRI study. MRI study included T2 W axial 3D FIESTA (Fast Imaging Employing Steady-state Acquisition) sequence. Anatomic abnormalities in each temporal bone were described and noted. For complete and better evaluation of Vestibulo-Cochlear Nerve (VCN) additional 3D oblique parasagittal view was taken perpendicular to the internal auditory canal with a small Field Of View (FOV). Results HRCT and MRI allowed accurate detection of inner ear malformations in children with bilateral SNHL. Majority of the patients presented with multiple structural abnormalities of inner ear. The common pathologies detected in the study were semicircular canal abnormality (89/144) followed by cochlear abnormalities (39/144). Most common cochlear abnormality was Mondini’s deformity (14/144). MRI demonstrated absent of vestibulo-cochlear nerve in 15 cases. Conclusion Few

  15. Clinical Utility of Positron Emission Tomography Magnetic Resonance Imaging (PET-MRI) in Gastrointestinal Cancers.

    PubMed

    Matthews, Robert; Choi, Minsig

    2016-09-09

    Anatomic imaging utilizing both CT (computed tomography) and MRI (magnetic resonance imaging) limits the assessment of cancer metastases in lymph nodes and distant organs while functional imaging like PET (positron emission tomography) scan has its limitation in spatial resolution capacity. Hybrid imaging utilizing PET-CT and PET-MRI are novel imaging modalities that are changing the current landscape in cancer diagnosis, staging, and treatment response. MRI has shown to have higher sensitivity in soft tissue, head and neck pathology, and pelvic disease, as well as, detecting small metastases in the liver and bone compared to CT. Combining MRI with PET allows for detection of metastases that may have been missed with current imaging modalities. In this review, we will examine the clinical utility of FDG PET-MRI in the diagnosis and staging of gastrointestinal cancers with focus on esophageal, stomach, colorectal, and pancreatic cancers. We will also explore its role in treatment response and future directions associated with it.

  16. A novel approach to image neural activity directly by MRI

    NASA Astrophysics Data System (ADS)

    Singh, Manbir; Sungkarat, Witaya

    2005-04-01

    Though an approach to image the electrical activity of neurons directly by detecting phase shifts in MRI was first reported in 1991, results to-date remain equivocal due to the low signal-to-noise ratio. The objective of this work was to develop a stimulus-presentation and data acquisition strategy specially geared to detect phase-dispersion effects of neuronal currents within 10-100 ms following stimulation. The key feature is to set the repeated MR data acquisition time TR and the stimulus presentation interval (TI) slightly different from each other so that the time at which images are acquired shifts gradually from one acquisition to the next with respect to stimulus onset. For example, at TR=275ms and 4 Hz stimulus presentation (TI=250ms), initial synchronization of the stimulus onset and MR acquisition would result in the first image being acquired at a latency of 0+/- (temporal width of data acquisition window), second image at a latency of 25ms, third image at a latency of 50ms and so on up to a latency of 250ms, at which time the stimulus and data acquisition times would become re-synchronized to once again acquire an image at latency=0. Human data were acquired on a 1.5T GE EXCITE scanner from two 8mm thick contiguous slices bracketing the calcarine fissure during a checkerboard flashing at 4 Hz. Preliminary results show activity in the visual cortex at latencies consistent with EEG studies, suggesting the potential of this methodology to image neural activity directly.

  17. TH-A-BRF-08: Deformable Registration of MRI and CT Images for MRI-Guided Radiation Therapy

    SciTech Connect

    Zhong, H; Wen, N; Gordon, J; Movsas, B; Chetty, I

    2014-06-15

    Purpose: To evaluate the quality of a commercially available MRI-CT image registration algorithm and then develop a method to improve the performance of this algorithm for MRI-guided prostate radiotherapy. Methods: Prostate contours were delineated on ten pairs of MRI and CT images using Eclipse. Each pair of MRI and CT images was registered with an intensity-based B-spline algorithm implemented in Velocity. A rectangular prism that contains the prostate volume was partitioned into a tetrahedral mesh which was aligned to the CT image. A finite element method (FEM) was developed on the mesh with the boundary constraints assigned from the Velocity generated displacement vector field (DVF). The resultant FEM displacements were used to adjust the Velocity DVF within the prism. Point correspondences between the CT and MR images identified within the prism could be used as additional boundary constraints to enforce the model deformation. The FEM deformation field is smooth in the interior of the prism, and equal to the Velocity displacements at the boundary of the prism. To evaluate the Velocity and FEM registration results, three criteria were used: prostate volume conservation and center consistence under contour mapping, and unbalanced energy of their deformation maps. Results: With the DVFs generated by the Velocity and FEM simulations, the prostate contours were warped from MRI to CT images. With the Velocity DVFs, the prostate volumes changed 10.2% on average, in contrast to 1.8% induced by the FEM DVFs. The average of the center deviations was 0.36 and 0.27 cm, and the unbalance energy was 2.65 and 0.38 mJ/cc3 for the Velocity and FEM registrations, respectively. Conclusion: The adaptive FEM method developed can be used to reduce the error of the MIbased registration algorithm implemented in Velocity in the prostate region, and consequently may help improve the quality of MRI-guided radiation therapy.

  18. Framework for 2D-3D image fusion of infrared thermography with preoperative MRI.

    PubMed

    Hoffmann, Nico; Weidner, Florian; Urban, Peter; Meyer, Tobias; Schnabel, Christian; Radev, Yordan; Schackert, Gabriele; Petersohn, Uwe; Koch, Edmund; Gumhold, Stefan; Steiner, Gerald; Kirsch, Matthias

    2017-01-23

    Multimodal medical image fusion combines information of one or more images in order to improve the diagnostic value. While previous applications mainly focus on merging images from computed tomography, magnetic resonance imaging (MRI), ultrasonic and single-photon emission computed tomography, we propose a novel approach for the registration and fusion of preoperative 3D MRI with intraoperative 2D infrared thermography. Image-guided neurosurgeries are based on neuronavigation systems, which further allow us track the position and orientation of arbitrary cameras. Hereby, we are able to relate the 2D coordinate system of the infrared camera with the 3D MRI coordinate system. The registered image data are now combined by calibration-based image fusion in order to map our intraoperative 2D thermographic images onto the respective brain surface recovered from preoperative MRI. In extensive accuracy measurements, we found that the proposed framework achieves a mean accuracy of 2.46 mm.

  19. Testing the quality of images for permanent magnet desktop MRI systems using specially designed phantoms.

    PubMed

    Qiu, Jianfeng; Wang, Guozhu; Min, Jiao; Wang, Xiaoyan; Wang, Pengcheng

    2013-12-21

    Our aim was to measure the performance of desktop magnetic resonance imaging (MRI) systems using specially designed phantoms, by testing imaging parameters and analysing the imaging quality. We designed multifunction phantoms with diameters of 18 and 60 mm for desktop MRI scanners in accordance with the American Association of Physicists in Medicine (AAPM) report no. 28. We scanned the phantoms with three permanent magnet 0.5 T desktop MRI systems, measured the MRI image parameters, and analysed imaging quality by comparing the data with the AAPM criteria and Chinese national standards. Image parameters included: resonance frequency, high contrast spatial resolution, low contrast object detectability, slice thickness, geometrical distortion, signal-to-noise ratio (SNR), and image uniformity. The image parameters of three desktop MRI machines could be measured using our specially designed phantoms, and most parameters were in line with MRI quality control criterion, including: resonance frequency, high contrast spatial resolution, low contrast object detectability, slice thickness, geometrical distortion, image uniformity and slice position accuracy. However, SNR was significantly lower than in some references. The imaging test and quality control are necessary for desktop MRI systems, and should be performed with the applicable phantom and corresponding standards.

  20. 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

  1. Single-Step Assembly of Multimodal Imaging Nanocarriers: MRI and Long-Wavelength Fluorescence Imaging.

    PubMed

    Pinkerton, Nathalie M; Gindy, Marian E; Calero-DdelC, Victoria L; Wolfson, Theodore; Pagels, Robert F; Adler, Derek; Gao, Dayuan; Li, Shike; Wang, Ruobing; Zevon, Margot; Yao, Nan; Pacheco, Carlos; Therien, Michael J; Rinaldi, Carlos; Sinko, Patrick J; Prud'homme, Robert K

    2015-06-24

    Magnetic resonance imaging (MRI)- and near-infrared (NIR)-active, multimodal composite nanocarriers (CNCs) are prepared using a simple one-step process, flash nanoprecipitation (FNP). The FNP process allows for the independent control of the hydrodynamic diameter, co-core excipient and NIR dye loading, and iron oxide-based nanocrystal (IONC) content of the CNCs. In the controlled precipitation process, 10 nm IONCs are encapsulated into poly(ethylene glycol) (PEG) stabilized CNCs to make biocompatible T2 contrast agents. By adjusting the formulation, CNC size is tuned between 80 and 360 nm. Holding the CNC size constant at an intensity weighted average diameter of 99 ± 3 nm (PDI width 28 nm), the particle relaxivity varies linearly with encapsulated IONC content ranging from 66 to 533 × 10(-3) m(-1) s(-1) for CNCs formulated with 4-16 wt% IONC. To demonstrate the use of CNCs as in vivo MRI contrast agents, CNCs are surface functionalized with liver-targeting hydroxyl groups. The CNCs enable the detection of 0.8 mm(3) non-small cell lung cancer metastases in mice livers via MRI. Incorporating the hydrophobic, NIR dye tris-(porphyrinato)zinc(II) into CNCs enables complementary visualization with long-wavelength fluorescence at 800 nm. In vivo imaging demonstrates the ability of CNCs to act both as MRI and fluorescent imaging agents.

  2. Unsupervised segmentation of MRI knees using image partition forests

    NASA Astrophysics Data System (ADS)

    Marčan, Marija; Voiculescu, Irina

    2016-03-01

    Nowadays many people are affected by arthritis, a condition of the joints with limited prevention measures, but with various options of treatment the most radical of which is surgical. In order for surgery to be successful, it can make use of careful analysis of patient-based models generated from medical images, usually by manual segmentation. In this work we show how to automate the segmentation of a crucial and complex joint -- the knee. To achieve this goal we rely on our novel way of representing a 3D voxel volume as a hierarchical structure of partitions which we have named Image Partition Forest (IPF). The IPF contains several partition layers of increasing coarseness, with partitions nested across layers in the form of adjacency graphs. On the basis of a set of properties (size, mean intensity, coordinates) of each node in the IPF we classify nodes into different features. Values indicating whether or not any particular node belongs to the femur or tibia are assigned through node filtering and node-based region growing. So far we have evaluated our method on 15 MRI knee images. Our unsupervised segmentation compared against a hand-segmented gold standard has achieved an average Dice similarity coefficient of 0.95 for femur and 0.93 for tibia, and an average symmetric surface distance of 0.98 mm for femur and 0.73 mm for tibia. The paper also discusses ways to introduce stricter morphological and spatial conditioning in the bone labelling process.

  3. Image Registration for Targeted MRI-guided Transperineal Prostate Biopsy

    PubMed Central

    Fedorov, Andriy; Tuncali, Kemal; Fennessy, Fiona M.; Tokuda, Junichi; Hata, Nobuhiko; Wells, William M.; Kikinis, Ron; Tempany, Clare M.

    2012-01-01

    Purpose To develop and evaluate image registration methodology for automated re-identification of tumor-suspicious foci from pre-procedural MR exams during MR-guided transperineal prostate core biopsy. Materials and Methods A hierarchical approach for automated registration between planning and intra-procedural T2-weighted prostate MRI was developed and evaluated on the images acquired during 10 consecutive MR-guided biopsies. Registration accuracy was quantified at image-based landmarks and by evaluating spatial overlap for the manually segmented prostate and sub-structures. Registration reliability was evaluated by simulating initial mis-registration and analyzing the convergence behavior. Registration precision was characterized at the planned biopsy targets. Results The total computation time was compatible with a clinical setting, being at most 2 minutes. Deformable registration led to a significant improvement in spatial overlap of the prostate and peripheral zone contours compared to both rigid and affine registration. Average in-slice landmark registration error was 1.3±0.5 mm. Experiments simulating initial mis-registration resulted in an estimated average capture range of 6 mm and an average in-slice registration precision of ±0.3 mm. Conclusion Our registration approach requires minimum user interaction and is compatible with the time constraints of our interventional clinical workflow. The initial evaluation shows acceptable accuracy, reliability and consistency of the method. PMID:22645031

  4. Image to physical space registration of supine breast MRI for image guided breast surgery

    NASA Astrophysics Data System (ADS)

    Conley, Rebekah H.; Meszoely, Ingrid M.; Pheiffer, Thomas S.; Weis, Jared A.; Yankeelov, Thomas E.; Miga, Michael I.

    2014-03-01

    Breast conservation therapy (BCT) is a desirable option for many women diagnosed with early stage breast cancer and involves a lumpectomy followed by radiotherapy. However, approximately 50% of eligible women will elect for mastectomy over BCT despite equal survival benefit (provided margins of excised tissue are cancer free) due to uncertainty in outcome with regards to complete excision of cancerous cells, risk of local recurrence, and cosmesis. Determining surgical margins intraoperatively is difficult and achieving negative margins is not as robust as it needs to be, resulting in high re-operation rates and often mastectomy. Magnetic resonance images (MRI) can provide detailed information about tumor margin extents, however diagnostic images are acquired in a fundamentally different patient presentation than that used in surgery. Therefore, the high quality diagnostic MRIs taken in the prone position with pendant breast are not optimal for use in surgical planning/guidance due to the drastic shape change between preoperative images and the common supine surgical position. This work proposes to investigate the value of supine MRI in an effort to localize tumors intraoperatively using image-guidance. Mock intraoperative setups (realistic patient positioning in non-sterile environment) and preoperative imaging data were collected from a patient scheduled for a lumpectomy. The mock intraoperative data included a tracked laser range scan of the patient's breast surface, tracked center points of MR visible fiducials on the patient's breast, and tracked B-mode ultrasound and strain images. The preoperative data included a supine MRI with visible fiducial markers. Fiducial markers localized in the MRI were rigidly registered to their mock intraoperative counterparts using an optically tracked stylus. The root mean square (RMS) fiducial registration error using the tracked markers was 3.4mm. Following registration, the average closest point distance between the MR

  5. Micro-imaging of the Mouse Lung via MRI

    NASA Astrophysics Data System (ADS)

    Wang, Wei

    Quantitative measurement of lung microstructure is of great significance in assessment of pulmonary disease, particularly in the earliest stages. Conventional stereological assessment of ex-vivo fixed tissue specimens under the microscope has a long and successful tradition and is regarded as a gold standard, but the invasive nature limits its applications and the practicality of use in longitudinal studies. The technique for diffusion MRI-based 3He lung morphometry was previously developed and validated for human lungs, and was recently extended to ex-vivo mouse lungs. The technique yields accurate, quantitative information about the microstructure and geometry of acinar airways. In this dissertation, the 3He lung morphometry technique is for the first time successfully implemented for in-vivo studies of mice. It can generate spatially-resolved maps of parameters that reveal the microstructure of mouse lung. Results in healthy mice indicate excellent agreement between in-vivo morphometry via 3He MRI and microscopic morphometry after sacrifice. The implementation and validation of 3He morphometry in healthy mice open up new avenues for application of the technique as a precise, noninvasive, in-vivo biomarker of changes in lung microstructure, within various mouse models of lung disease. We have applied 3He morphometry to the Sendai mouse model of lung disease. Specifically, the Sendai-virus model of chronic obstructive lung disease has demonstrated an innate immune response in mouse airways that exhibits similarities to the chronic airway inflammation in human COPD and asthma, but the effect on distal lung parenchyma had not been investigated. We imaged the time course and regional distribution of mouse lung microstructural changes in vivo after Sendai virus (SeV) infection with 1H and 3He diffusion MRI. 1H MR images detected the SeV-induced pulmonary inflammation in vivo and 3He lung morphometry showed modest increase in alveolar duct radius distal to airway

  6. NOTE: A feasibility study of markerless fluoroscopic gating for lung cancer radiotherapy using 4DCT templates

    NASA Astrophysics Data System (ADS)

    Li, Ruijiang; Lewis, John H.; Cerviño, Laura I.; Jiang, Steve B.

    2009-10-01

    A major difficulty in conformal lung cancer radiotherapy is respiratory organ motion, which may cause clinically significant targeting errors. Respiratory-gated radiotherapy allows for more precise delivery of prescribed radiation dose to the tumor, while minimizing normal tissue complications. Gating based on external surrogates is limited by its lack of accuracy, while gating based on implanted fiducial markers is limited primarily by the risk of pneumothorax due to marker implantation. Techniques for fluoroscopic gating without implanted fiducial markers (markerless gating) have been developed. These techniques usually require a training fluoroscopic image dataset with marked tumor positions in the images, which limits their clinical implementation. To remove this requirement, this study presents a markerless fluoroscopic gating algorithm based on 4DCT templates. To generate gating signals, we explored the application of three similarity measures or scores between fluoroscopic images and the reference 4DCT template: un-normalized cross-correlation (CC), normalized cross-correlation (NCC) and normalized mutual information (NMI), as well as average intensity (AI) of the region of interest (ROI) in the fluoroscopic images. Performance was evaluated using fluoroscopic and 4DCT data from three lung cancer patients. On average, gating based on CC achieves the highest treatment accuracy given the same efficiency, with a high target coverage (average between 91.9% and 98.6%) for a wide range of nominal duty cycles (20-50%). AI works well for two patients out of three, but failed for the third patient due to interference from the heart. Gating based on NCC and NMI usually failed below 50% nominal duty cycle. Based on this preliminary study with three patients, we found that the proposed CC-based gating algorithm can generate accurate and robust gating signals when using 4DCT reference template. However, this observation is based on results obtained from a very limited

  7. Vision 20/20: Simultaneous CT-MRI--Next chapter of multimodality imaging.

    PubMed

    Wang, Ge; Kalra, Mannudeep; Murugan, Venkatesh; Xi, Yan; Gjesteby, Lars; Getzin, Matthew; Yang, Qingsong; Cong, Wenxiang; Vannier, Michael

    2015-10-01

    Multimodality imaging systems such as positron emission tomography-computed tomography (PET-CT) and MRI-PET are widely available, but a simultaneous CT-MRI instrument has not been developed. Synergies between independent modalities, e.g., CT, MRI, and PET/SPECT can be realized with image registration, but such postprocessing suffers from registration errors that can be avoided with synchronized data acquisition. The clinical potential of simultaneous CT-MRI is significant, especially in cardiovascular and oncologic applications where studies of the vulnerable plaque, response to cancer therapy, and kinetic and dynamic mechanisms of targeted agents are limited by current imaging technologies. The rationale, feasibility, and realization of simultaneous CT-MRI are described in this perspective paper. The enabling technologies include interior tomography, unique gantry designs, open magnet and RF sequences, and source and detector adaptation. Based on the experience with PET-CT, PET-MRI, and MRI-LINAC instrumentation where hardware innovation and performance optimization were instrumental to construct commercial systems, the authors provide top-level concepts for simultaneous CT-MRI to meet clinical requirements and new challenges. Simultaneous CT-MRI fills a major gap of modality coupling and represents a key step toward the so-called "omnitomography" defined as the integration of all relevant imaging modalities for systems biology and precision medicine.

  8. Vision 20/20: Simultaneous CT-MRI — Next chapter of multimodality imaging

    SciTech Connect

    Wang, Ge Xi, Yan; Gjesteby, Lars; Getzin, Matthew; Yang, Qingsong; Cong, Wenxiang; Vannier, Michael

    2015-10-15

    Multimodality imaging systems such as positron emission tomography-computed tomography (PET-CT) and MRI-PET are widely available, but a simultaneous CT-MRI instrument has not been developed. Synergies between independent modalities, e.g., CT, MRI, and PET/SPECT can be realized with image registration, but such postprocessing suffers from registration errors that can be avoided with synchronized data acquisition. The clinical potential of simultaneous CT-MRI is significant, especially in cardiovascular and oncologic applications where studies of the vulnerable plaque, response to cancer therapy, and kinetic and dynamic mechanisms of targeted agents are limited by current imaging technologies. The rationale, feasibility, and realization of simultaneous CT-MRI are described in this perspective paper. The enabling technologies include interior tomography, unique gantry designs, open magnet and RF sequences, and source and detector adaptation. Based on the experience with PET-CT, PET-MRI, and MRI-LINAC instrumentation where hardware innovation and performance optimization were instrumental to construct commercial systems, the authors provide top-level concepts for simultaneous CT-MRI to meet clinical requirements and new challenges. Simultaneous CT-MRI fills a major gap of modality coupling and represents a key step toward the so-called “omnitomography” defined as the integration of all relevant imaging modalities for systems biology and precision medicine.

  9. CT fluoroscopic guided insertion of inferior vena cava filters.

    PubMed

    Ignotus, P; Wetton, C; Berry, J

    2006-03-01

    The value and use of inferior vena cava (IVC) filters is well documented and has been growing since the first reported filter placement in 1973 and the first percutaneous insertion in 1982. Access routes now include both jugular veins, both ante-cubital veins and both femoral veins. However, all insertions require some form of imaging, usually fluoroscopy, to identify the location of the filter with respect to the IVC and the renal veins. We describe two cases where the patients' weight was significantly greater than the weight limit of the angiography table, necessitating insertion under CT fluoroscopic guidance.

  10. Association of multiparametric MRI quantitative imaging features with prostate cancer gene expression in MRI-targeted prostate biopsies

    PubMed Central

    Stoyanova, Radka; Pollack, Alan; Takhar, Mandeep; Lynne, Charles; Parra, Nestor; Lam, Lucia L.C.; Alshalalfa, Mohammed; Buerki, Christine; Castillo, Rosa; Jorda, Merce; Ashab, Hussam Al-deen; Kryvenko, Oleksandr N.; Punnen, Sanoj; Parekh, Dipen J.; Abramowitz, Matthew C.; Gillies, Robert J.; Davicioni, Elai; Erho, Nicholas; Ishkanian, Adrian

    2016-01-01

    Standard clinicopathological variables are inadequate for optimal management of prostate cancer patients. While genomic classifiers have improved patient risk classification, the multifocality and heterogeneity of prostate cancer can confound pre-treatment assessment. The objective was to investigate the association of multiparametric (mp)MRI quantitative features with prostate cancer risk gene expression profiles in mpMRI-guided biopsies tissues. Global gene expression profiles were generated from 17 mpMRI-directed diagnostic prostate biopsies using an Affimetrix platform. Spatially distinct imaging areas (‘habitats’) were identified on MRI/3D-Ultrasound fusion. Radiomic features were extracted from biopsy regions and normal appearing tissues. We correlated 49 radiomic features with three clinically available gene signatures associated with adverse outcome. The signatures contain genes that are over-expressed in aggressive prostate cancers and genes that are under-expressed in aggressive prostate cancers. There were significant correlations between these genes and quantitative imaging features, indicating the presence of prostate cancer prognostic signal in the radiomic features. Strong associations were also found between the radiomic features and significantly expressed genes. Gene ontology analysis identified specific radiomic features associated with immune/inflammatory response, metabolism, cell and biological adhesion. To our knowledge, this is the first study to correlate radiogenomic parameters with prostate cancer in men with MRI-guided biopsy. PMID:27438142

  11. Interhemispheric neuroplasticity following limb deafferentation detected by resting-state functional connectivity magnetic resonance imaging (fcMRI) and functional magnetic resonance imaging (fMRI)

    PubMed Central

    Pawela, Christopher P.; Biswal, Bharat B.; Hudetz, Anthony G.; Li, Rupeng; Jones, Seth R.; Cho, Younghoon R.; Matloub, Hani S.; Hyde, James S.

    2009-01-01

    Functional connectivity magnetic resonance imaging (fcMRI) studies in rat brain show brain reorganization following peripheral nerve injury. Subacute neuroplasticity was observed two weeks following transection of the four major nerves of the brachial plexus. Direct functional magnetic resonance imaging (fMRI) stimulation of the intact radial nerve reveals an activation pattern in the forelimb regions of the sensory and motor cortices that is significantly different from that observed in normal rats. Results of this fMRI experiment were used to determine seed voxel regions for fcMRI analysis. Intrahemispheric connectivities in the sensorimotor forelimb representations in both hemispheres are largely unaffected by deafferentation, whereas substantial disruption of interhemispheric sensorimotor cortical connectivity occurs. In addition, significant intra- and interhemispheric changes in connectivities of thalamic nuclei were found. These are the central findings of the study. They could not have been obtained from fMRI studies alone—both fMRI and fcMRI are needed. The combination provides a general marker for brain plasticity. The rat visual system was studied in the same animals as a control. No neuroplastic changes in connectivities were found in the primary visual cortex upon forelimb deafferentation. Differences were noted in regions responsible for processing multisensory visual-motor information. This incidental discovery is considered to be significant. It may provide insight into phantom limb epiphenomena. PMID:19796693

  12. Three-dimensional curvilinear device reconstruction from two fluoroscopic views

    NASA Astrophysics Data System (ADS)

    Delmas, Charlotte; Berger, Marie-Odile; Kerrien, Erwan; Riddell, Cyril; Trousset, Yves; Anxionnat, René; Bracard, Serge

    2015-03-01

    In interventional radiology, navigating devices under the sole guidance of fluoroscopic images inside a complex architecture of tortuous and narrow vessels like the cerebral vascular tree is a difficult task. Visualizing the device in 3D could facilitate this navigation. For curvilinear devices such as guide-wires and catheters, a 3D reconstruction may be achieved using two simultaneous fluoroscopic views, as available on a biplane acquisition system. The purpose of this paper is to present a new automatic three-dimensional curve reconstruction method that has the potential to reconstruct complex 3D curves and does not require a perfect segmentation of the endovascular device. Using epipolar geometry, our algorithm translates the point correspondence problem into a segment correspondence problem. Candidate 3D curves can be formed and evaluated independently after identifying all possible combinations of compatible 3D segments. Correspondence is then inherently solved by looking in 3D space for the most coherent curve in terms of continuity and curvature. This problem can be cast into a graph problem where the most coherent curve corresponds to the shortest path of a weighted graph. We present quantitative results of curve reconstructions performed from numerically simulated projections of tortuous 3D curves extracted from cerebral vascular trees affected with brain arteriovenous malformations as well as fluoroscopic image pairs of a guide-wire from both phantom and clinical sets. Our method was able to select the correct 3D segments in 97.5% of simulated cases thus demonstrating its ability to handle complex 3D curves and can deal with imperfect 2D segmentation.

  13. Echo Planar Imaging before and after fMRI: A personal history

    PubMed Central

    Cohen, Mark S.; Schmitt, Franz

    2012-01-01

    Echo-planar imaging (EPI) plays a crucial role in functional MRI. Focusing especially on the period from 1988 to 1992, the authors offer personal recollections, on the development of practical means of deploying EPI, the people that participated, and its impact on MRI in general. PMID:22266173

  14. DCE-MRI, DW-MRI, and MRS in Cancer: Challenges and Advantages of Implementing Qualitative and Quantitative Multi-parametric Imaging in the Clinic

    PubMed Central

    Winfield, Jessica M.; Payne, Geoffrey S.; Weller, Alex; deSouza, Nandita M.

    2016-01-01

    Abstract Multi-parametric magnetic resonance imaging (mpMRI) offers a unique insight into tumor biology by combining functional MRI techniques that inform on cellularity (diffusion-weighted MRI), vascular properties (dynamic contrast-enhanced MRI), and metabolites (magnetic resonance spectroscopy) and has scope to provide valuable information for prognostication and response assessment. Challenges in the application of mpMRI in the clinic include the technical considerations in acquiring good quality functional MRI data, development of robust techniques for analysis, and clinical interpretation of the results. This article summarizes the technical challenges in acquisition and analysis of multi-parametric MRI data before reviewing the key applications of multi-parametric MRI in clinical research and practice. PMID:27748710

  15. New Jersey's Thomas Edison and the fluoroscope.

    PubMed

    Tselos, G D

    1995-11-01

    Thomas Edison played a major role in the development of early x-ray technology in 1896, notably increasing tube power and reliability and making the fluoroscope a practical instrument. Eventually, Edison would move x-ray technology from the laboratory to the marketplace.

  16. Delineating potential epileptogenic areas utilizing resting functional magnetic resonance imaging (fMRI) in epilepsy patients.

    PubMed

    Pizarro, Ricardo; Nair, Veena; Meier, Timothy; Holdsworth, Ryan; Tunnell, Evelyn; Rutecki, Paul; Sillay, Karl; Meyerand, Mary E; Prabhakaran, Vivek

    2016-08-01

    Seizure localization includes neuroimaging like electroencephalogram, and magnetic resonance imaging (MRI) with limited ability to characterize the epileptogenic network. Temporal clustering analysis (TCA) characterizes epileptogenic network congruent with interictal epileptiform discharges by clustering together voxels with transient signals. We generated epileptogenic areas for 12 of 13 epilepsy patients with TCA, congruent with different areas of seizure onset. Resting functional MRI (fMRI) scans are noninvasive, and can be acquired quickly, in patients with different levels of severity and function. Analyzing resting fMRI data using TCA is quick and can complement clinical methods to characterize the epileptogenic network.

  17. A study on the magnetic resonance imaging (MRI)-based radiation treatment planning of intracranial lesions

    NASA Astrophysics Data System (ADS)

    Stanescu, T.; Jans, H.-S.; Pervez, N.; Stavrev, P.; Fallone, B. G.

    2008-07-01

    The aim of this study is to develop a magnetic resonance imaging (MRI)-based treatment planning procedure for intracranial lesions. The method relies on (a) distortion correction of raw magnetic resonance (MR) images by using an adaptive thresholding and iterative technique, (b) autosegmentation of head structures relevant to dosimetric calculations (scalp, bone and brain) using an atlas-based software and (c) conversion of MR images into computed tomography (CT)-like images by assigning bulk CT values to organ contours and dose calculations performed in Eclipse (Philips Medical Systems). Standard CT + MRI-based and MRI-only plans were compared by means of isodose distributions, dose volume histograms and several dosimetric parameters. The plans were also ranked by using a tumor control probability (TCP)-based technique for heterogeneous irradiation, which is independent of radiobiological parameters. For our 3 T Intera MRI scanner (Philips Medical Systems), we determined that the total maximum image distortion corresponding to a typical brain study was about 4 mm. The CT + MRI and MRI-only plans were found to be in good agreement for all patients investigated. Following our clinical criteria, the TCP-based ranking tool shows no significant difference between the two types of plans. This indicates that the proposed MRI-based treatment planning procedure is suitable for the radiotherapy of intracranial lesions.

  18. Imaging in arthritis: quantifying effects of therapeutic intervention using MRI and molecular imaging.

    PubMed

    Cimmino, Marco A; Barbieri, Francesca; Zampogna, Giuseppe; Camellino, Dario; Paparo, Francesco; Parodi, Massimiliano

    2012-01-05

    Modern imaging techniques are becoming increasingly important in assessing the course of arthritis and in permitting measurement of response to treatment as part of the follow-up of patients. They include ultrasonography (US), MRI, PET/CT, and biofluorescence. In patients with rheumatoid arthritis, clinical evaluation is significantly less sensitive than either US or MRI in detecting synovitis. As a result, imaging is a useful alternative to achieving proper assessment of disease activity. The different areas in which the new imaging techniques could help practicing rheumatologists and internal physicians include the following: early and differential diagnosis of arthritis, evaluation of disease activity, prognosis, assessment of treatment efficacy, assessment of remission, and evaluation of subclinical disease. MRI is probably the best imaging method to study disease activity in RA, because it can study all the joints with similar efficacy, has been sufficiently standardised, and yields data on inflammation that can be quantified. Different methods, developed to score synovitis activity, are increasingly used in clinical trials. The main application of PET/CT in rheumatology is the diagnosis and follow-up of large vessel vasculitis. More recently, also RA disease activity has been evaluated, allowing a panoramic view of the patient. Molecular imaging studies molecular and cellular processes in intact living organisms in a non-invasive fashion. In fluorescence, dyes, that emit light upon excitation by a light source and are read by a camera, can be used to show inflamed areas where neoangiogenesis, vasodilatation, and increased vessel permeability are present. These dyes can be coupled with different compounds including antibodies and drugs.

  19. Rapid ex vivo imaging of PAIII prostate to bone tumor with SWIFT-MRI

    PubMed Central

    Luhach, Ihor; Idiyatullin, Djaudat; Lynch, Conor C.; Corum, Curt; Martinez, Gary V.; Garwood, Michael; Gillies, Robert J.

    2013-01-01

    Introduction The limiting factor for MRI of skeletal/mineralized tissue is fast transverse relaxation. A recent advancement in MRI technology, SWIFT (Sweep Imaging with Fourier Transform), is emerging as a new approach to overcome this difficulty. Among other techniques like UTE, ZTE and WASPI, the application of SWIFT technology has the strong potential to impact preclinical and clinical imaging, particularly in the context of primary or metastatic bone cancers since it has the added advantage of imaging water in mineralized tissues of bone allowing MRI images to be obtained of tissues previously visible only with modalities such as CT. The goal of the current study is to examine the feasibility of SWIFT for the assessment of the prostate cancer induced changes in bone formation (osteogenesis) and destruction (osteolysis) in ex vivo specimens. Methods A luciferase expressing prostate cancer cell line (PAIII) or saline control was inoculated directly into the tibia of 6-week old immunocompromised male mice. Tumor growth was assessed weekly for three weeks prior to euthanasia and dissection of the tumor bearing and sham tibias. The ex vivo mouse tibia specimens were imaged with a 9.4T and 7T MRI systems. SWIFT images are compared with traditional gradient-echo and spin-echo MRI images as well as CT and histological sections. Results SWIFT images with nominal resolution of 78 μm are obtained with the tumor and different bone structures identified. Prostate cancer induced changes in the bone microstructure are visible in SWIFT images, which is supported by spin-echo, high resolution CT and histological analysis. Conclusions SWIFT MRI is capable of high-quality high-resolution ex vivo imaging of bone tumor and surrounding bone and soft tissues. Furthermore, SWIFT MRI shows promise for in vivo bone tumor imaging, with the added benefits of non-exposure to ionizing radiation, quietness and speed. PMID:24155275

  20. Three-dimensional magnetic resonance imaging overlay to assist with percutaneous transhepatic access at the time of cardiac catheterization

    PubMed Central

    Whiteside, Wendy; Christensen, Jason; Zampi, Jeffrey D

    2015-01-01

    Multimodality image overlay is increasingly used for complex interventional procedures in the cardiac catheterization lab. We report a case in which three-dimensional magnetic resonance imaging (3D MRI) overlay onto live fluoroscopic imaging was utilized to safely obtain transhepatic access in a 12-year-old patient with prune belly syndrome, complex and distorted abdominal anatomy, and a vascular mass within the liver. PMID:26085770

  1. Structural Image Analysis of the Brain in Neuropsychology Using Magnetic Resonance Imaging (MRI) Techniques.

    PubMed

    Bigler, Erin D

    2015-09-01

    Magnetic resonance imaging (MRI) of the brain provides exceptional image quality for visualization and neuroanatomical classification of brain structure. A variety of image analysis techniques provide both qualitative as well as quantitative methods to relate brain structure with neuropsychological outcome and are reviewed herein. Of particular importance are more automated methods that permit analysis of a broad spectrum of anatomical measures including volume, thickness and shape. The challenge for neuropsychology is which metric to use, for which disorder and the timing of when image analysis methods are applied to assess brain structure and pathology. A basic overview is provided as to the anatomical and pathoanatomical relations of different MRI sequences in assessing normal and abnormal findings. Some interpretive guidelines are offered including factors related to similarity and symmetry of typical brain development along with size-normalcy features of brain anatomy related to function. The review concludes with a detailed example of various quantitative techniques applied to analyzing brain structure for neuropsychological outcome studies in traumatic brain injury.

  2. [The Diagnostic Value of Pre-Biopsy Magnetic Resonance Imaging (MRI) for Detecting Prostate Cancer].

    PubMed

    Mori, Kohei; Miyoshi, Yasuhide; Yoneyama, Shuko; Ishida, Hiroaki; Hattori, Yusuke; Teranishi, Jun-ichi; Kondo, Keiichi; Noguchi, Kazumi

    2016-01-01

    We examined the value of pre-biopsy magnetic resonance imaging (MRI) for detecting prostate cancer. We analyzed 267 men with prostate-specific antigen (PSA) levels of 3-10 ng/ml who underwent systematic prostate needle biopsy. From April 2009 to March 2011, a total of 98 male patients underwent 16-core prostatic biopsies without pre-biopsy magnetic resonance imaging (MRI) (nonenforcement group). From April 2011 to March 2013, 169 men underwent pre-biopsy MRI [T2-weighted imaging (T2WI) and diffusion-weighted imaging (DWI)] (enforcement group). When MRI findings indicated cancer in the latter group, in addition to the systematic 16-core biopsy one or two targeted biopsies were performed. Patients without suspicious MRI findings underwent only systematic 16-core biopsy. Cancer detection rates in the nonenforcement and enforcement groups were 42.9% (48/92) and 46. 2% (78/169), respectively. The difference did not reach significance (p=0.612). Although the cancer detection rates were 39.4% (41/104) in the MRI-negative group and 56. 9% (37/65) in the MRI-positive group (p=0.039), the sensitivity and specificity for cancer detection by MRI were relatively low: 47.4% and 69.2%, respectively. By receiver-operating curve analysis, the area under the curve for cancer detection by MRI was only 0.583. There were two study limitations. First, the patient sample size was small. Second, it is unclear whether an adequate sample of the suspicious lesion was obtained by biopsy. We thus demonstrated that it might be improper to base a diagnosis solely on pre-biopsy MRI (T2WI and DWI) findings in men with serum PSA levels of 3-10 ng/ml.

  3. MRI Safety during Pregnancy

    MedlinePlus

    ... News Physician Resources Professions Site Index A-Z MRI Safety During Pregnancy Magnetic resonance imaging (MRI) Illness ... during the exam? Contrast material MRI during pregnancy Magnetic resonance imaging (MRI) If you are pregnant and your doctor ...

  4. MRI-SPECT image registration using multiple MR pulse sequences to examine osteoarthritis of the knee

    NASA Astrophysics Data System (ADS)

    Lynch, John A.; Peterfy, Charles G.; White, David L.; Hawkins, Randall A.; Genant, Harry K.

    1999-05-01

    We have examined whether automated image registration can be used to combine metabolic information from SPECT knee scans with anatomical information from MRI. Ten patients, at risk of developing OA due to meniscal surgery, were examined. 99mTc methyldiphosphonate SPECT, T2-weighted fast spin echo (FSE) MRI, and T1-weighted, 3D fat-suppressed gradient recalled echo (SPGR) MRI images were obtained. Registration was performed using normalized mutual information. For each patient, FSE data was registered to SPGR data, providing a composite MRI image with each voxel represented by two intensities (ISPGR, IFSE). Modifications to the registration algorithm were made to allow registration of SPECT data (one intensity per voxel) to composite MRI data (2 intensities per voxel). Registration sources was assessed by visual inspection of uptake localization over expected anatomical locations, and the absence of uptake over unlikely sites. Three patients were discarded from SPECT-MRI registration tests since they had metallic artifacts that prevented co-registration of MR data. Registration of SPECT to SPGR or FSE data alone proved unreliable, with less than 50% of attempts succeeding. The modified algorithm, treating co-registered SPGR and FSE data as a two-value-per-voxel image, proved most reliable, allowing registration of all patients with no metallic artifacts on MRI.

  5. Magnetic Resonance Imaging (MRI): Lumbar Spine (For Parents)

    MedlinePlus

    ... cause a problem near a strong magnetic field. Electronic devices aren't permitted in the MRI room. ... child may be given headphones to listen to music or earplugs to block the noise, and will ...

  6. Reliability of Early Magnetic Resonance Imaging (MRI) and Necessity of Repeating MRI in Noncooled and Cooled Infants With Neonatal Encephalopathy.

    PubMed

    Chakkarapani, Elavazhagan; Poskitt, Kenneth J; Miller, Steven P; Zwicker, Jill G; Xu, Qi; Wong, Darren S T; Roland, Elke H; Hill, Alan; Chau, Vann

    2016-04-01

    In cooled newborns with encephalopathy, although late magnetic resonance imaging (MRI) scan (10-14 days of age) is reliable in predicting long-term outcome, it is unknown whether early scan (3-6 days of life) is. We compared the predominant pattern and extent of lesion between early and late MRI in 89 term neonates with neonatal encephalopathy. Forty-three neonates (48%) were cooled. The predominant pattern of lesions and the extent of lesion in the watershed region agreed near perfectly in noncooled (kappa = 0.94; k = 0.88) and cooled (k = 0.89; k = 0.87) infants respectively. There was perfect agreement in the extent of lesion in the basal nuclei in noncooled infants (k = 0.83) and excellent agreement in cooled infants (k = 0.67). Changes in extent of lesions on late MRI occurred in 19 of 89 infants, with higher risk in infants with hypoglycemia and moderate-severe lesions in basal nuclei. In most term neonates with neonatal encephalopathy, early MRI (relative to late scan) robustly predicts the predominant pattern and extent of injury.

  7. Order of magnitude reduction of fluoroscopic x-ray dose

    NASA Astrophysics Data System (ADS)

    Bal, Abhinav; Robert, Normand; Machan, Lindsay; Deutsch, Meir; Kisselgoff, David; Babyn, Paul; Rowlands, John A.

    2012-03-01

    The role of fluoroscopic imaging is critical for diagnostic and image guided therapy. However, fluoroscopic imaging can require significant radiation leading to increased cancer risk and non-stochastic effects such as radiation burns. Our purpose is to reduce the exposure and dose to the patient by an order of magnitude in these procedures by use of the region of interest method. Method and Materials: Region of interest fluoroscopy (ROIF) uses a partial attenuator. The central region of the image has full exposure while the image periphery, there to provide context only, has a reduced exposure rate. ROIF using a static partial attenuator has been shown in our previous studies to reduce the dose area product (DAP) to the patient by at least 2.5 times. Significantly greater reductions in DAP would require improvements in flat panel detectors performance at low x-ray exposures or a different x-ray attenuation strategy. Thus we have investigated a second, dynamic, approach. We have constructed an x-ray shutter system allowing a normal x-ray exposure in the region of interest while reducing the number of x-ray exposures in the periphery through the rapid introduction, positioning and removal of an x-ray attenuating shutter to block radiation only for selected frames. This dynamic approach eliminates the DQE(0) loss associated with the use of static partial attenuator applied to every frame thus permitting a greater reduction in DAP. Results: We have compared the two methods by modeling and determined their fundamental limits.

  8. An iterative reconstruction method of complex images using expectation maximization for radial parallel MRI

    NASA Astrophysics Data System (ADS)

    Choi, Joonsung; Kim, Dongchan; Oh, Changhyun; Han, Yeji; Park, HyunWook

    2013-05-01

    In MRI (magnetic resonance imaging), signal sampling along a radial k-space trajectory is preferred in certain applications due to its distinct advantages such as robustness to motion, and the radial sampling can be beneficial for reconstruction algorithms such as parallel MRI (pMRI) due to the incoherency. For radial MRI, the image is usually reconstructed from projection data using analytic methods such as filtered back-projection or Fourier reconstruction after gridding. However, the quality of the reconstructed image from these analytic methods can be degraded when the number of acquired projection views is insufficient. In this paper, we propose a novel reconstruction method based on the expectation maximization (EM) method, where the EM algorithm is remodeled for MRI so that complex images can be reconstructed. Then, to optimize the proposed method for radial pMRI, a reconstruction method that uses coil sensitivity information of multichannel RF coils is formulated. Experiment results from synthetic and in vivo data show that the proposed method introduces better reconstructed images than the analytic methods, even from highly subsampled data, and provides monotonic convergence properties compared to the conjugate gradient based reconstruction method.

  9. The Rightful Role of MRI after Negative Conventional Imaging in the Management of Bloody Nipple Discharge.

    PubMed

    Sanders, Linda M; Daigle, Megan

    2016-01-01

    Nipple discharge is a frequent presenting complaint at breast clinics. Bloody nipple discharge (BND) has the highest risk of malignancy, albeit low. If mammogram and ultrasound are unrevealing, central duct excision (CDE) has been considered the gold standard in its management. Magnetic resonance imaging (MRI) has been widely confirmed as a highly sensitive test for detection of breast cancer, with an accompanying high negative predictive value. This article presents a retrospective review of patients with BND and negative conventional imaging, comparing outcome of patients who went directly to CDE without MRI to those patients who underwent preoperative MRI. Of 115 patients who underwent mammography and US alone prior to CDE, eight cancers were detected (seven ductal carcinoma in situ [DCIS] and 1 IDC, 7 mm [T1b]; incidence: 7%). Of 85 patients who underwent conventional imaging followed by MRI prior to surgery, eight cancers were detected (all DCIS; incidence: 9.4%), seven of which were identified by MRI. The one false-negative MRI had subtle findings which, in retrospect, were misinterpreted; however, a clinically apparent nipple lesion prompted surgical biopsy. Of 56 patients with a negative or benign MRI, CDE was negative for malignancy in all but that one patient. Sensitivity and specificity were 87.5%/71.4%. Positive predictive value and negative predictive value (NPV) were 24.1%/98.2%. MRI should be performed in all patients with BND and negative conventional imaging. The extremely high NPV of MRI suggests that a negative study could obviate CDE in most patients unless overriding clinical factors prevail.

  10. Fluoroscopic chest tube insertion and patient care.

    PubMed Central

    Collins, J. D.; Shaver, M. L.; Disher, A. C.; Miller, T. Q.

    1992-01-01

    Catheters and chest tubes may be placed under fluoroscopic control to reduce pleural effusions. This procedure has been adopted as a routine procedure at the UCLA School of Medicine in Los Angeles, California to improve patient care. This technique was modified for the placement of large chest tubes, which can be placed by a radiologist without multiple attempts or complications. Our experience with 2234 patients who underwent this procedure between 1977 and 1990 is described. PMID:1404463

  11. Selecting magnetic resonance imaging (MRI) outcome measures for juvenile idiopathic arthritis (JIA) clinical trials: first report of the MRI in JIA special interest group.

    PubMed

    Hemke, Robert; Doria, Andrea S; Tzaribachev, Nikolay; Maas, Mario; van der Heijde, Désirée M F M; van Rossum, Marion A J

    2014-02-01

    Recent advances in magnetic resonance imaging (MRI) techniques have substantially improved the evaluation of joint pathologies in juvenile idiopathic arthritis (JIA). Because of the current availability of highly effective antirheumatic therapies and the unique and useful features of MRI, there is a growing need for an accurate and reproducible MRI assessment scoring system for JIA, such as the rheumatoid arthritis MRI Scoring (RAMRIS) for patients with rheumatoid arthritis (RA). To effectively evaluate the efficacy of treatment in clinical research trials, we need to develop and validate scoring methods to accurately measure joint outcomes, standardize imaging protocols for data acquisition and interpretation, and create imaging atlases to differentiate physiologic and pathologic joint findings in childhood and adolescence. Such a standardized, validated, JIA-MRI scoring method could be used as an outcome measure in clinical trials.

  12. SU-E-P-15: Technique Factor Modulation and Reference Plane Air Kerma Rates in Response to Simulated Patient Thickness Variations for a Sample of Current Generation Fluoroscopes

    SciTech Connect

    Wunderle, K; Rakowski, J; Dong, F

    2015-06-15

    Purpose: To evaluate and compare approaches to technique factor modulation and air kerma rates in response to simulated patient thickness variations for four state-of-the-art and one previous-generation interventional fluoroscopes. Methods: A polymethyl methacrylate (PMMA) phantom was used as a tissue surrogate for the purposes of determining fluoroscopic reference plane air kerma rates, kVp, mA, and spectral filtration over a wide range of simulated tissue thicknesses. Data were acquired for each fluoroscopic and acquisition dose curve within a default abdomen or body imaging protocol. Results: The data obtained indicated vendor- and model-specific variations in the approach to technique factor modulation and reference plane air kerma rates across a range of tissue thicknesses. Some vendors have made hardware advances increasing the radiation output capabilities of their fluoroscopes; this was evident in the acquisition air kerma rates. However, in the imaging protocol evaluated, all of the state-of-the-art systems had relatively low air kerma rates in the fluoroscopic low-dose imaging mode as compared to the previous-generation unit. Each of the newest-generation systems also employ copper filtration in the selected protocol in the acquisition mode of imaging; this is a substantial benefit, reducing the skin entrance dose to the patient in the highest dose-rate mode of fluoroscope operation. Conclusion: Understanding how fluoroscopic technique factors are modulated provides insight into the vendor-specific image acquisition approach and provides opportunities to optimize the imaging protocols for clinical practice. The enhanced radiation output capabilities of some of the fluoroscopes may, under specific conditions, may be beneficial; however, these higher output capabilities also have the potential to lead to unnecessarily high dose rates. Therefore, all parties involved in imaging, including the clinical team, medical physicists, and imaging vendors, must work

  13. Semi-automatic delineation using weighted CT-MRI registered images for radiotherapy of nasopharyngeal cancer

    SciTech Connect

    Fitton, I.; Cornelissen, S. A. P.; Duppen, J. C.; Rasch, C. R. N.; Herk, M. van; Steenbakkers, R. J. H. M.; Peeters, S. T. H.; Hoebers, F. J. P.; Kaanders, J. H. A. M.; Nowak, P. J. C. M.

    2011-08-15

    Purpose: To develop a delineation tool that refines physician-drawn contours of the gross tumor volume (GTV) in nasopharynx cancer, using combined pixel value information from x-ray computed tomography (CT) and magnetic resonance imaging (MRI) during delineation. Methods: Operator-guided delineation assisted by a so-called ''snake'' algorithm was applied on weighted CT-MRI registered images. The physician delineates a rough tumor contour that is continuously adjusted by the snake algorithm using the underlying image characteristics. The algorithm was evaluated on five nasopharyngeal cancer patients. Different linear weightings CT and MRI were tested as input for the snake algorithm and compared according to contrast and tumor to noise ratio (TNR). The semi-automatic delineation was compared with manual contouring by seven experienced radiation oncologists. Results: A good compromise for TNR and contrast was obtained by weighing CT twice as strong as MRI. The new algorithm did not notably reduce interobserver variability, it did however, reduce the average delineation time by 6 min per case. Conclusions: The authors developed a user-driven tool for delineation and correction based a snake algorithm and registered weighted CT image and MRI. The algorithm adds morphological information from CT during the delineation on MRI and accelerates the delineation task.

  14. Clinical Utility of Positron Emission Tomography Magnetic Resonance Imaging (PET-MRI) in Gastrointestinal Cancers

    PubMed Central

    Matthews, Robert; Choi, Minsig

    2016-01-01

    Anatomic imaging utilizing both CT (computed tomography) and MRI (magnetic resonance imaging) limits the assessment of cancer metastases in lymph nodes and distant organs while functional imaging like PET (positron emission tomography) scan has its limitation in spatial resolution capacity. Hybrid imaging utilizing PET-CT and PET-MRI are novel imaging modalities that are changing the current landscape in cancer diagnosis, staging, and treatment response. MRI has shown to have higher sensitivity in soft tissue, head and neck pathology, and pelvic disease, as well as, detecting small metastases in the liver and bone compared to CT. Combining MRI with PET allows for detection of metastases that may have been missed with current imaging modalities. In this review, we will examine the clinical utility of FDG PET-MRI in the diagnosis and staging of gastrointestinal cancers with focus on esophageal, stomach, colorectal, and pancreatic cancers. We will also explore its role in treatment response and future directions associated with it. PMID:27618106

  15. MRI

    MedlinePlus

    ... sweatpants and a t-shirt). Certain types of metal can cause blurry images. You will lie on ... placed artificial joints Vascular stents Worked with sheet metal in the past (you may need tests to ...

  16. PET-MRI: a review of challenges and solutions in the development of integrated multimodality imaging

    NASA Astrophysics Data System (ADS)

    Vandenberghe, Stefaan; Marsden, Paul K.

    2015-02-01

    The integration of positron emission tomography (PET) and magnetic resonance imaging (MRI) has been an ongoing research topic for the last 20 years. This paper gives an overview of the different developments and the technical problems associated with combining PET and MRI in one system. After explaining the different detector concepts for integrating PET-MRI and minimising interference the limitations and advantages of different solutions for the detector and system are described for preclinical and clinical imaging systems. The different integrated PET-MRI systems are described in detail. Besides detector concepts and system integration the challenges and proposed solutions for attenuation correction and the potential for motion correction and resolution recovery are also discussed in this topical review.

  17. Diagnoses in Pediatric Patients With Magnetic Resonance Imaging (MRI) Lesions Suspicious for Demyelination.

    PubMed

    Sweeney, Michael L; Kukreja, Marcia; Horn, Paul S; Standridge, Shannon M

    2015-10-01

    Magnetic resonance imaging (MRI) studies of the brain in pediatric patients frequently show abnormal white matter lesions, which may be concerning for demyelinating disease. This study aimed to determine the proportion of pediatric patients who have MRI lesions concerning for demyelinating disease at presentation and ultimately are diagnosed with a primary central nervous system demyelinating disease. A retrospective chart review was performed on MRI reports of patients who underwent imaging evaluation at a single tertiary pediatric hospital. Of 299 patients identified, 192 presented with acute neurologic complaints. In this group, ≥ 5 discrete lesions, African American race, and having brain stem, thalamic, cerebellar, or optic nerve lesions was associated with the patient being diagnosed with a disease that required further treatment. The other 107 patients underwent MRI for other indications. Among these subjects, having lesions within the corpus callosum or cerebellum was associated with being diagnosed with a disease requiring further treatment.

  18. Functional MRI and diffusion tensor imaging of brain reorganization after experimental stroke.

    PubMed

    Dijkhuizen, Rick M; van der Marel, Kajo; Otte, Willem M; Hoff, Erik I; van der Zijden, Jet P; van der Toorn, Annette; van Meer, Maurits P A

    2012-03-01

    The potential of the adult brain to reorganize after ischemic injury is critical for functional recovery and provides a significant target for therapeutic strategies to promote brain repair. Despite the accumulating evidence of brain plasticity, the interaction and significance of morphological and physiological modifications in post-stroke brain tissue remain mostly unclear. Neuroimaging techniques such as functional MRI (fMRI) and diffusion tensor imaging (DTI) enable in vivo assessment of the spatial and temporal pattern of functional and structural changes inside and outside ischemic lesion areas. This can contribute to the elucidation of critical aspects in post-stroke brain remodeling. Task/stimulus-related fMRI, resting-state fMRI, or pharmacological MRI enables direct or indirect measurement of neuronal activation, functional connectivity, or neurotransmitter system responses, respectively. DTI allows estimation of the structural integrity and connectivity of white matter tracts. Together, these MRI methods provide an unprecedented means to (a) measure longitudinal changes in tissue structure and function close by and remote from ischemic lesion areas, (b) evaluate the organizational profile of neural networks after stroke, and (c) identify degenerative and restorative processes that affect post-stroke functional outcome. Besides, the availability of MRI in clinical institutions as well as research laboratories provides an optimal basis for translational research on stroke recovery. This review gives an overview of the current status and perspectives of fMRI and DTI applications to study brain reorganization in experimental stroke models.

  19. Interpreting Intervention Induced Neuroplasticity with fMRI: The Case for Multimodal Imaging Strategies

    PubMed Central

    Reid, Lee B.; Boyd, Roslyn N.; Cunnington, Ross; Rose, Stephen E.

    2016-01-01

    Direct measurement of recovery from brain injury is an important goal in neurorehabilitation, and requires reliable, objective, and interpretable measures of changes in brain function, referred to generally as “neuroplasticity.” One popular imaging modality for measuring neuroplasticity is task-based functional magnetic resonance imaging (t-fMRI). In the field of neurorehabilitation, however, assessing neuroplasticity using t-fMRI presents a significant challenge. This commentary reviews t-fMRI changes commonly reported in patients with cerebral palsy or acquired brain injuries, with a focus on studies of motor rehabilitation, and discusses complexities surrounding their interpretations. Specifically, we discuss the difficulties in interpreting t-fMRI changes in terms of their underlying causes, that is, differentiating whether they reflect genuine reorganisation, neurological restoration, compensation, use of preexisting redundancies, changes in strategy, or maladaptive processes. Furthermore, we discuss the impact of heterogeneous disease states and essential t-fMRI processing steps on the interpretability of activation patterns. To better understand therapy-induced neuroplastic changes, we suggest that researchers utilising t-fMRI consider concurrently acquiring information from an additional modality, to quantify, for example, haemodynamic differences or microstructural changes. We outline a variety of such supplementary measures for investigating brain reorganisation and discuss situations in which they may prove beneficial to the interpretation of t-fMRI data. PMID:26839711

  20. 2D dose distribution images of a hybrid low field MRI-γ detector

    NASA Astrophysics Data System (ADS)

    Abril, A.; Agulles-Pedrós, L.

    2016-07-01

    The proposed hybrid system is a combination of a low field MRI and dosimetric gel as a γ detector. The readout system is based on the polymerization process induced by the gel radiation. A gel dose map is obtained which represents the functional part of hybrid image alongside with the anatomical MRI one. Both images should be taken while the patient with a radiopharmaceutical is located inside the MRI system with a gel detector matrix. A relevant aspect of this proposal is that the dosimetric gel has never been used to acquire medical images. The results presented show the interaction of the 99mTc source with the dosimetric gel simulated in Geant4. The purpose was to obtain the planar γ 2D-image. The different source configurations are studied to explore the ability of the gel as radiation detector through the following parameters; resolution, shape definition and radio-pharmaceutical concentration.

  1. Effects of magnetic resonance imaging (MRI) on the formation of mouse dentin and bone

    SciTech Connect

    Kwong-Hing, A.; Sandhu, H.S.; Prato, F.S.; Frappier, J.R.; Kavaliers, M. )

    1989-10-01

    The effects of magnetic resonance imaging (MRI) on dentin and bone formation in mice were examined using standard autoradiographic and liquid scintillation procedures. It was observed that exposure to a standard 23.2 min clinical multislice MRI (0.15T) procedure caused a significant increase in the synthesis of the collagenous matrix of dentin in the incisors of mice. There were no significant effects on alveolar and tibial bone matrix synthesis. These results suggest that the magnetic fields associated with MRI can affect the activity of cells and/or tissues that are involved in rapid synthetic activity.

  2. Isolated sixth cranial nerve aplasia visualized with Fast Imaging Employing Steady-State Acquisition (FIESTA) MRI.

    PubMed

    Pilyugina, Svetlana A; Fischbein, Nancy J; Liao, Y Joyce; McCulley, Timothy J

    2007-06-01

    An otherwise healthy 12-month-old girl presented for evaluation of reduced abduction of the left eye detected at 6 months of age. The remainder of the examination was unremarkable. A special MRI sequence-fast imaging employing steady-state acquisition (FIESTA)-visualized the right but not the left sixth nerve cisternal segment. This is the first reported use of the MRI FIESTA sequence to diagnose aplasia of the sixth cranial nerve.

  3. 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.

  4. Optimizing the imaging of the monkey auditory cortex: sparse vs. continuous fMRI.

    PubMed

    Petkov, Christopher I; Kayser, Christoph; Augath, Mark; Logothetis, Nikos K

    2009-10-01

    The noninvasive imaging of the monkey auditory system with functional magnetic resonance imaging (fMRI) can bridge the gap between electrophysiological studies in monkeys and imaging studies in humans. Some of the recent imaging of monkey auditory cortical and subcortical structures relies on a technique of "sparse imaging," which was developed in human studies to sidestep the negative influence of scanner noise by adding periods of silence in between volume acquisition. Among the various aspects that have gone into the ongoing optimization of fMRI of the monkey auditory cortex, replacing the more common continuous-imaging paradigm with sparse imaging seemed to us to make the most obvious difference in the amount of activity that we could reliably obtain from awake or anesthetized animals. Here, we directly compare the sparse- and continuous-imaging paradigms in anesthetized animals. We document a strikingly greater auditory response with sparse imaging, both quantitatively and qualitatively, which includes a more expansive and robust tonotopic organization. There were instances where continuous imaging could better reveal organizational properties that sparse imaging missed, such as aspects of the hierarchical organization of auditory cortex. We consider the choice of imaging paradigm as a key component in optimizing the fMRI of the monkey auditory cortex.

  5. MRI-guided brain PET image filtering and partial volume correction.

    PubMed

    Yan, Jianhua; Lim, Jason Chu-Shern; Townsend, David W

    2015-02-07

    Positron emission tomography (PET) image quantification is a challenging problem due to limited spatial resolution of acquired data and the resulting partial volume effects (PVE), which depend on the size of the structure studied in relation to the spatial resolution and which may lead to over or underestimation of the true tissue tracer concentration. In addition, it is usually necessary to perform image smoothing either during image reconstruction or afterwards to achieve a reasonable signal-to-noise ratio. Typically, an isotropic Gaussian filtering (GF) is used for this purpose. However, the noise suppression is at the cost of deteriorating spatial resolution. As hybrid imaging devices such as PET/MRI have become available, the complementary information derived from high definition morphologic images could be used to improve the quality of PET images. In this study, first of all, we propose an MRI-guided PET filtering method by adapting a recently proposed local linear model and then incorporate PVE into the model to get a new partial volume correction (PVC) method without parcellation of MRI. In addition, both the new filtering and PVC are voxel-wise non-iterative methods. The performance of the proposed methods were investigated with simulated dynamic FDG brain dataset and (18)F-FDG brain data of a cervical cancer patient acquired with a simultaneous hybrid PET/MR scanner. The initial simulation results demonstrated that MRI-guided PET image filtering can produce less noisy images than traditional GF and bias and coefficient of variation can be further reduced by MRI-guided PET PVC. Moreover, structures can be much better delineated in MRI-guided PET PVC for real brain data.

  6. MRI-guided brain PET image filtering and partial volume correction

    NASA Astrophysics Data System (ADS)

    Yan, Jianhua; Chu-Shern Lim, Jason; Townsend, David W.

    2015-02-01

    Positron emission tomography (PET) image quantification is a challenging problem due to limited spatial resolution of acquired data and the resulting partial volume effects (PVE), which depend on the size of the structure studied in relation to the spatial resolution and which may lead to over or underestimation of the true tissue tracer concentration. In addition, it is usually necessary to perform image smoothing either during image reconstruction or afterwards to achieve a reasonable signal-to-noise ratio. Typically, an isotropic Gaussian filtering (GF) is used for this purpose. However, the noise suppression is at the cost of deteriorating spatial resolution. As hybrid imaging devices such as PET/MRI have become available, the complementary information derived from high definition morphologic images could be used to improve the quality of PET images. In this study, first of all, we propose an MRI-guided PET filtering method by adapting a recently proposed local linear model and then incorporate PVE into the model to get a new partial volume correction (PVC) method without parcellation of MRI. In addition, both the new filtering and PVC are voxel-wise non-iterative methods. The performance of the proposed methods were investigated with simulated dynamic FDG brain dataset and 18F-FDG brain data of a cervical cancer patient acquired with a simultaneous hybrid PET/MR scanner. The initial simulation results demonstrated that MRI-guided PET image filtering can produce less noisy images than traditional GF and bias and coefficient of variation can be further reduced by MRI-guided PET PVC. Moreover, structures can be much better delineated in MRI-guided PET PVC for real brain data.

  7. MRI contrast agent for molecular imaging of the HER2/neu receptor using targeted magnetic nanoparticles

    NASA Astrophysics Data System (ADS)

    Rasaneh, Samira; Rajabi, Hossein; Babaei, Mohammad Hossein; Akhlaghpoor, Shahram

    2011-06-01

    In this study, Trastuzumab modified Magnetic Nanoparticles (TMNs) were prepared as a new contrast agent for detecting HER2 (Human epidermal growth factor receptor-2) expression tumors by magnetic resonance imaging (MRI). TMNs were prepared based on iron oxide nanoparticles core and Trastuzumab modified dextran coating. The TMNs core and hydrodynamic size were determined by transmission electron microscopy and dynamic light scattering. TMNs stability and cytotoxicity were investigated. The ability of TMNs for HER2 detection were evaluated in breast carcinoma cell lines (SKBr3 and MCF7 cells) and tumor-bearing mice by MRI and iron uptake determination. The particles core and hydrodynamic size were 9 ± 2.5 and 41 ± 15 nm (size range: 15-87 nm), respectively. The molar antibody/nanoparticle ratio was 3.1-3.5. TMNs were non-toxic to the cells below the 30 μg (Fe)/mL concentration and good stable up to 8 weeks in PBS buffer. TMNs could detect HER2 oncogenes in the cells surface with imagable contrast by MRI. The invivo study in mice bearing tumors indicated that TMNs possessed a good diagnostic ability as HER2 specific contrast agent by MRI. TMNs were demonstrated to be able to selectively accumulate in the tumor cells, with a proper signal enhancement in MRI T2 images. So, the complex may be considered for further investigations as an MRI contrast agent for detection of HER2 expression tumors in human.

  8. Imaging transplanted stem cells in real time using an MRI dual-contrast method

    PubMed Central

    Ngen, Ethel J.; Wang, Lee; Kato, Yoshinori; Krishnamachary, Balaji; Zhu, Wenlian; Gandhi, Nishant; Smith, Barbara; Armour, Michael; Wong, John; Gabrielson, Kathleen; Artemov, Dmitri

    2015-01-01

    Stem cell therapies are currently being investigated for the repair of brain injuries. Although exogenous stem cell labelling with superparamagnetic iron oxide nanoparticles (SPIONs) prior to transplantation provides a means to noninvasively monitor stem cell transplantation by magnetic resonance imaging (MRI), monitoring cell death is still a challenge. Here, we investigate the feasibility of using an MRI dual-contrast technique to detect cell delivery, cell migration and cell death after stem cell transplantation. Human mesenchymal stem cells were dual labelled with SPIONs and gadolinium-based chelates (GdDTPA). The viability, proliferation rate, and differentiation potential of the labelled cells were then evaluated. The feasibility of this MRI technique to distinguish between live and dead cells was next evaluated using MRI phantoms, and in vivo using both immune-competent and immune-deficient mice, following the induction of brain injury in the mice. All results were validated with bioluminescence imaging. In live cells, a negative (T2/T2*) MRI contrast predominates, and is used to track cell delivery and cell migration. Upon cell death, a diffused positive (T1) MRI contrast is generated in the vicinity of the dead cells, and serves as an imaging marker for cell death. Ultimately, this technique could be used to manage stem cell therapies. PMID:26330231

  9. Three-dimensional, in vivo MRI with self-gating and image coregistration in the mouse.

    PubMed

    Nieman, Brian J; Szulc, Kamila U; Turnbull, Daniel H

    2009-05-01

    Motion during magnetic resonance imaging (MRI) scans routinely results in undesirable image artifact or blurring. Since high-resolution, three-dimensional (3D) imaging of the mouse requires long scan times for satisfactory signal-to-noise ratio (SNR) and image quality, motion-related artifacts are likely over much of the body and limit applications of mouse MRI. In this investigation, we explored the use of self-gated imaging methods and image coregistration for improving image quality in the presence of motion. Self-gated signal results from a modified 3D gradient-echo sequence showed detection of periodic respiratory and cardiac motion in the adult mouse-with excellent comparison to traditional measurements, sensitivity to respiration-induced tissue changes in the brain, and even detection of embryonic cardiac motion in utero. Serial image coregistration with rapidly-acquired, low-SNR volumes further enabled detection and correction of bulk changes in embryo location during in utero imaging sessions and subsequent reconstruction of high-quality images. These methods, in combination, are shown to expand the range of applications for 3D mouse MRI, enabling late-stage embryonic heart imaging and introducing the possibility of longitudinal developmental studies from embryonic stages through adulthood.

  10. Comparison of Echo and MRI in the Imaging Evaluation of Intracardiac Masses

    SciTech Connect

    Gulati, G. Sharma, S.; Kothari, S.S.; Juneja, R.; Saxena, A.; Talwar, K.K.

    2004-09-15

    We compared the efficacy of echocardiography (ECHO) and magnetic resonance imaging (MRI) for evaluating intracardiac masses. Over an 8-yr period, 28 patients, 21 males, 7 females, 16 days-60 years of age (mean 25 years) with a suspected intracardiac mass on ECHO (transthoracic in all; transesophageal in 9) underwent an MRI examination. Five patients had a contrast-enhanced MRI. ECHO and MRI were compared with respect to their technical adequacy, ability to detect and suggest the likely etiology of the mass, and provide additional information (masses not seen with the other technique, inflow or outflow obstruction, and intramural component of an intracavitary mass). With MRI, the image morphology (including signal intensity changes on the various sequences) and extracardiac manifestations were also evaluated. The diagnosis was confirmed by histopathology in 18, surgical inspection in 4, by follow- up imaging on conservative management in 5, and by typical extracardiac manifestations of the disease in 1 patient.Fifteen (54%) patients had tumors (benign 12, malignant 3), 5 had a thrombus or hematoma, and 4 each had infective or vascular lesions. Thirty-four masses (13 in ventricle, 11 septal, 7 atrial, 2 on valve and 1 in pulmonary artery) were seen on MRI, 28 of which were detected by ECHO. Transthoracic ECHO (TTE) and MRI were technically optimal in 82% and 100% of cases, respectively. Nine patients needed an additional transesophageal ECHO (TEE). Overall, MRI showed a mass in all patients, whereas ECHO missed it in 2 cases. In cases with a mass on both modalities, MRI detected 4 additional masses not seen on ECHO. MRI suggested the etiology in 21 (75%) cases, while the same was possible with ECHO (TTE and TEE) in 8 (29%) cases. Intramural component, extension into the inflow or outflow, outflow tract obstruction, and associated pericardial or extracardiac masses were better depicted on MRI. We conclude that MRI is advantageous over a combination of TTE and TEE for

  11. gr-MRI: A software package for magnetic resonance imaging using software defined radios

    NASA Astrophysics Data System (ADS)

    Hasselwander, Christopher J.; Cao, Zhipeng; Grissom, William A.

    2016-09-01

    The goal of this work is to develop software that enables the rapid implementation of custom MRI spectrometers using commercially-available software defined radios (SDRs). The developed gr-MRI software package comprises a set of Python scripts, flowgraphs, and signal generation and recording blocks for GNU Radio, an open-source SDR software package that is widely used in communications research. gr-MRI implements basic event sequencing functionality, and tools for system calibrations, multi-radio synchronization, and MR signal processing and image reconstruction. It includes four pulse sequences: a single-pulse sequence to record free induction signals, a gradient-recalled echo imaging sequence, a spin echo imaging sequence, and an inversion recovery spin echo imaging sequence. The sequences were used to perform phantom imaging scans with a 0.5 Tesla tabletop MRI scanner and two commercially-available SDRs. One SDR was used for RF excitation and reception, and the other for gradient pulse generation. The total SDR hardware cost was approximately 2000. The frequency of radio desynchronization events and the frequency with which the software recovered from those events was also measured, and the SDR's ability to generate frequency-swept RF waveforms was validated and compared to the scanner's commercial spectrometer. The spin echo images geometrically matched those acquired using the commercial spectrometer, with no unexpected distortions. Desynchronization events were more likely to occur at the very beginning of an imaging scan, but were nearly eliminated if the user invoked the sequence for a short period before beginning data recording. The SDR produced a 500 kHz bandwidth frequency-swept pulse with high fidelity, while the commercial spectrometer produced a waveform with large frequency spike errors. In conclusion, the developed gr-MRI software can be used to develop high-fidelity, low-cost custom MRI spectrometers using commercially-available SDRs.

  12. gr-MRI: A software package for magnetic resonance imaging using software defined radios.

    PubMed

    Hasselwander, Christopher J; Cao, Zhipeng; Grissom, William A

    2016-09-01

    The goal of this work is to develop software that enables the rapid implementation of custom MRI spectrometers using commercially-available software defined radios (SDRs). The developed gr-MRI software package comprises a set of Python scripts, flowgraphs, and signal generation and recording blocks for GNU Radio, an open-source SDR software package that is widely used in communications research. gr-MRI implements basic event sequencing functionality, and tools for system calibrations, multi-radio synchronization, and MR signal processing and image reconstruction. It includes four pulse sequences: a single-pulse sequence to record free induction signals, a gradient-recalled echo imaging sequence, a spin echo imaging sequence, and an inversion recovery spin echo imaging sequence. The sequences were used to perform phantom imaging scans with a 0.5Tesla tabletop MRI scanner and two commercially-available SDRs. One SDR was used for RF excitation and reception, and the other for gradient pulse generation. The total SDR hardware cost was approximately $2000. The frequency of radio desynchronization events and the frequency with which the software recovered from those events was also measured, and the SDR's ability to generate frequency-swept RF waveforms was validated and compared to the scanner's commercial spectrometer. The spin echo images geometrically matched those acquired using the commercial spectrometer, with no unexpected distortions. Desynchronization events were more likely to occur at the very beginning of an imaging scan, but were nearly eliminated if the user invoked the sequence for a short period before beginning data recording. The SDR produced a 500kHz bandwidth frequency-swept pulse with high fidelity, while the commercial spectrometer produced a waveform with large frequency spike errors. In conclusion, the developed gr-MRI software can be used to develop high-fidelity, low-cost custom MRI spectrometers using commercially-available SDRs.

  13. Single element ultrasonic imaging of limb geometry: an in-vivo study with comparison to MRI

    NASA Astrophysics Data System (ADS)

    Zhang, Xiang; Fincke, Jonathan R.; Anthony, Brian W.

    2016-04-01

    Despite advancements in medical imaging, current prosthetic fitting methods remain subjective, operator dependent, and non-repeatable. The standard plaster casting method relies on prosthetist experience and tactile feel of the limb to design the prosthetic socket. Often times, many fitting iterations are required to achieve an acceptable fit. Use of improper socket fittings can lead to painful pathologies including neuromas, inflammation, soft tissue calcification, and pressure sores, often forcing the wearer to into a wheelchair and reducing mobility and quality of life. Computer software along with MRI/CT imaging has already been explored to aid the socket design process. In this paper, we explore the use of ultrasound instead of MRI/CT to accurately obtain the underlying limb geometry to assist the prosthetic socket design process. Using a single element ultrasound system, multiple subjects' proximal limbs were imaged using 1, 2.25, and 5 MHz single element transducers. Each ultrasound transducer was calibrated to ensure acoustic exposure within the limits defined by the FDA. To validate image quality, each patient was also imaged in an MRI. Fiducial markers visible in both MRI and ultrasound were used to compare the same limb cross-sectional image for each patient. After applying a migration algorithm, B-mode ultrasound cross-sections showed sufficiently high image resolution to characterize the skin and bone boundaries along with the underlying tissue structures.

  14. Reconstruction of 7T-Like Images From 3T MRI

    PubMed Central

    Bahrami, Khosro; Shi, Feng; Zong, Xiaopeng; Shin, Hae Won; An, Hongyu

    2016-01-01

    In the recent MRI scanning, ultra-high-field (7T) MR imaging provides higher resolution and better tissue contrast compared to routine 3T MRI, which may help in more accurate and early brain diseases diagnosis. However, currently, 7T MRI scanners are more expensive and less available at clinical and research centers. These motivate us to propose a method for the reconstruction of images close to the quality of 7T MRI, called 7T-like images, from 3T MRI, to improve the quality in terms of resolution and contrast. By doing so, the post-processing tasks, such as tissue segmentation, can be done more accurately and brain tissues details can be seen with higher resolution and contrast. To do this, we have acquired a unique dataset which includes paired 3T and 7T images scanned from same subjects, and then propose a hierarchical reconstruction based on group sparsity in a novel multi-level Canonical Correlation Analysis (CCA) space, to improve the quality of 3T MR image to be 7T-like MRI. First, overlapping patches are extracted from the input 3T MR image. Then, by extracting the most similar patches from all the aligned 3T and 7T images in the training set, the paired 3T and 7T dictionaries are constructed for each patch. It is worth noting that, for the training, we use pairs of 3T and 7T MR images from each training subject. Then, we propose multi-level CCA to map the paired 3T and 7T patch sets to a common space to increase their correlations. In such space, each input 3T MRI patch is sparsely represented by the 3T dictionary and then the obtained sparse coefficients are used together with the corresponding 7T dictionary to reconstruct the 7T-like patch. Also, to have the structural consistency between adjacent patches, the group sparsity is employed. This reconstruction is performed with changing patch sizes in a hierarchical framework. Experiments have been done using 13 subjects with both 3T and 7T MR images. The results show that our method outperforms previous

  15. Reconstruction of 7T-Like Images From 3T MRI.

    PubMed

    Bahrami, Khosro; Shi, Feng; Zong, Xiaopeng; Shin, Hae Won; An, Hongyu; Shen, Dinggang

    2016-09-01

    In the recent MRI scanning, ultra-high-field (7T) MR imaging provides higher resolution and better tissue contrast compared to routine 3T MRI, which may help in more accurate and early brain diseases diagnosis. However, currently, 7T MRI scanners are more expensive and less available at clinical and research centers. These motivate us to propose a method for the reconstruction of images close to the quality of 7T MRI, called 7T-like images, from 3T MRI, to improve the quality in terms of resolution and contrast. By doing so, the post-processing tasks, such as tissue segmentation, can be done more accurately and brain tissues details can be seen with higher resolution and contrast. To do this, we have acquired a unique dataset which includes paired 3T and 7T images scanned from same subjects, and then propose a hierarchical reconstruction based on group sparsity in a novel multi-level Canonical Correlation Analysis (CCA) space, to improve the quality of 3T MR image to be 7T-like MRI. First, overlapping patches are extracted from the input 3T MR image. Then, by extracting the most similar patches from all the aligned 3T and 7T images in the training set, the paired 3T and 7T dictionaries are constructed for each patch. It is worth noting that, for the training, we use pairs of 3T and 7T MR images from each training subject. Then, we propose multi-level CCA to map the paired 3T and 7T patch sets to a common space to increase their correlations. In such space, each input 3T MRI patch is sparsely represented by the 3T dictionary and then the obtained sparse coefficients are used together with the corresponding 7T dictionary to reconstruct the 7T-like patch. Also, to have the structural consistency between adjacent patches, the group sparsity is employed. This reconstruction is performed with changing patch sizes in a hierarchical framework. Experiments have been done using 13 subjects with both 3T and 7T MR images. The results show that our method outperforms previous

  16. Lung tumor tracking in fluoroscopic video based on optical flow.

    PubMed

    Xu, Qianyi; Hamilton, Russell J; Schowengerdt, Robert A; Alexander, Brian; Jiang, Steve B

    2008-12-01

    Respiratory gating and tumor tracking for dynamic multileaf collimator delivery require accurate and real-time localization of the lung tumor position during treatment. Deriving tumor position from external surrogates such as abdominal surface motion may have large uncertainties due to the intra- and interfraction variations of the correlation between the external surrogates and internal tumor motion. Implanted fiducial markers can be used to track tumors fluoroscopically in real time with sufficient accuracy. However, it may not be a practical procedure when implanting fiducials bronchoscopically. In this work, a method is presented to track the lung tumor mass or relevant anatomic features projected in fluoroscopic images without implanted fiducial markers based on an optical flow algorithm. The algorithm generates the centroid position of the tracked target and ignores shape changes of the tumor mass shadow. The tracking starts with a segmented tumor projection in an initial image frame. Then, the optical flow between this and all incoming frames acquired during treatment delivery is computed as initial estimations of tumor centroid displacements. The tumor contour in the initial frame is transferred to the incoming frames based on the average of the motion vectors, and its positions in the incoming frames are determined by fine-tuning the contour positions using a template matching algorithm with a small search range. The tracking results were validated by comparing with clinician determined contours on each frame. The position difference in 95% of the frames was found to be less than 1.4 pixels (approximately 0.7 mm) in the best case and 2.8 pixels (approximately 1.4 mm) in the worst case for the five patients studied.

  17. Strain Rate Tensor Estimation in Cine Cardiac MRI Based on Elastic Image Registration

    NASA Astrophysics Data System (ADS)

    Sánchez-Ferrero, Gonzalo Vegas; Vega, Antonio Tristán; Grande, Lucilio Cordero; de La Higuera, Pablo Casaseca; Fernández, Santiago Aja; Fernández, Marcos Martín; López, Carlos Alberola

    In this work we propose an alternative method to estimate and visualize the Strain Rate Tensor (SRT) in Magnetic Resonance Images (MRI) when Phase Contrast MRI (PCMRI) and Tagged MRI (TMRI) are not available. This alternative is based on image processing techniques. Concretely, image registration algorithms are used to estimate the movement of the myocardium at each point. Additionally, a consistency checking method is presented to validate the accuracy of the estimates when no golden standard is available. Results prove that the consistency checking method provides an upper bound of the mean squared error of the estimate. Our experiments with real data show that the registration algorithm provides a useful deformation field to estimate the SRT fields. A classification between regional normal and dysfunctional contraction patterns, as compared with experts diagnosis, points out that the parameters extracted from the estimated SRT can represent these patterns. Additionally, a scheme for visualizing and analyzing the local behavior of the SRT field is presented.

  18. Identification and description of the axillary web syndrome (AWS) by clinical signs, MRI and US imaging.

    PubMed

    Leduc, O; Fumière, E; Banse, S; Vandervorst, C; Clément, A; Parijs, T; Wilputte, F; Maquerlot, F; Ezquer Echandia, M; Tinlot, A; Leduc, A

    2014-12-01

    The Axillary Web Syndrome (AWS) follows surgery for breast neoplasia and consists of one, or more frequently two or three, cords of subcutaneous tissue. Cords originate from the axilla, spread to the antero-medial surface of the arm down to the elbow and then move into the antero-medial aspect of the forearm and sometimes into the root of the thumb. The purpose of this study was to compare two techniques, ultrasound (US) and Magnetic Resonance Imaging (MRI) for their sensitivity and accuracy in identifying AWS cords and to provide insights to the origin of this pathology. US examinations were performed on fifteen patients using a high frequency probe (17 MHz). We first palpated and marked the cord with location aided by maximum abduction. To identify the cord with MRI (1.5 Tesla), a catheter filled with a gel detectable under MRI was placed on the skin at the site of the cord. We found that in some US cases, the dynamic abduction maneuver was essential to facilitate detection of the cord. This dynamic method on ultrasound confirmed the precise location of the cord even if it was located deeper in the hypodermis fascia junction. US and MRI images revealed features of the cords and surrounding tissues. Imaging the cords was difficult with either of the imaging modalities. However, US seemed to be more efficient than MRI and allowed dynamic evaluation. Overall analysis of our study results supports a lymphatic origin of the AWS cord.

  19. Multimodal imaging with hybrid semiconductor detectors Timepix for an experimental MRI-SPECT system

    NASA Astrophysics Data System (ADS)

    Zajicek, J.; Jakubek, J.; Burian, M.; Vobecky, M.; Fauler, A.; Fiederle, M.; Zwerger, A.

    2013-01-01

    An increasing number of clinical applications are being based on multimodal imaging systems (MIS), including anatomical (CT, MRI) and functional (PET, SPECT) techniques to provide complex information in a single image. CT with one of the scintigraphic methods (PET or SPECT) is nowadays a combination of choice for clinical practice and it is mostly used in cardiography and tumour diagnostics. Combination with MRI is also being implemented as no radiation dose is imparted to the patient and it is possible to gain higher structural resolution of soft tissues (brain imaging). A major disadvantage of such systems is inability to operate scintillators with photomultipliers (used for detection of γ rays) in presence of high magnetic fields. In this work we present the application of the semiconductor pixel detector for SPECT method in combination with MR imaging. We propose a novel approach based on MRI compatible setup with CdTe pixel sensor Timepix and non-conductive collimator. Measurements were performed on high proton-density (PD) phantom (1H) with an embedded radioisotopic source inside the shielded RF coil by MRI animal scanner (4.7 T). Our results pave the way for a combined MRI-SPECT system. The project was performed in the framework of the Medipix Collaboration.

  20. Plain radiography or magnetic resonance imaging (MRI): Which is better in assessing outcome in clinical trials of disease-modifying osteoarthritis drugs? Summary of a debate held at the World Congress of Osteoarthritis 2014.

    PubMed

    Eckstein, Felix; Le Graverand, Marie-Pierre Hellio

    2015-12-01

    Osteoarthritis (OA) is the most common disease of synovial joints and currently lacks treatment options that modify structural pathology. Imaging is ideally suited for directly evaluating efficacy of disease-modifying OA drugs (DMOADs) in clinical trials, with plain radiography and MRI being most often applied. The current article is based on a debate held on April 26, 2014, at the World Congress of Osteoarthritis: The authors were invited to contrast strengths and limitations of both methods, highlighting scientific evidence on reliability, construct-validity, and correlations with clinical outcome, and comparing their sensitivity to change in knee OA and sensitivity to DMOAD treatment. The authors concluded that MRI provides more comprehensive information on articular tissues pathology, and that implementation of radiography in clinical trials remains a challenge. However, neither technique has thus far been demonstrated to be strongly superior over the other; for the time being it therefore appears advisable to use both in parallel in clinical trials, to provide more evidence on their relative performance. Radiographic JSW strongly depends on adequate positioning; it is not specific to cartilage loss but also to the meniscus. MRI provides somewhat superior sensitivity to change compared with the commonly used non-fluoroscopic radiographic acquisition protocols, and has recently provided non-location-dependent measures of cartilage thickness loss and gain, which are potentially more sensitive in detecting DMOAD effects than radiographic JSW or region-specific MRI. Non-location-dependent measures of cartilage thickness change should thus be explored further in context of anabolic and anti-catabolic DMOADs.

  1. Evaluation of image quality of MRI data for brain tumor surgery

    NASA Astrophysics Data System (ADS)

    Heckel, Frank; Arlt, Felix; Geisler, Benjamin; Zidowitz, Stephan; Neumuth, Thomas

    2016-03-01

    3D medical images are important components of modern medicine. Their usefulness for the physician depends on their quality, though. Only high-quality images allow accurate and reproducible diagnosis and appropriate support during treatment. We have analyzed 202 MRI images for brain tumor surgery in a retrospective study. Both an experienced neurosurgeon and an experienced neuroradiologist rated each available image with respect to its role in the clinical workflow, its suitability for this specific role, various image quality characteristics, and imaging artifacts. Our results show that MRI data acquired for brain tumor surgery does not always fulfill the required quality standards and that there is a significant disagreement between the surgeon and the radiologist, with the surgeon being more critical. Noise, resolution, as well as the coverage of anatomical structures were the most important criteria for the surgeon, while the radiologist was mainly disturbed by motion artifacts.

  2. Fluoroscopic performance tests using a portable computer/frame grabber: Wiener spectra measurements.

    PubMed

    Goldman, L W

    1992-01-01

    Currently, routine tests of fluoroscopic image quality in common use are highly subjective. As part of an effort to develop more quantitative routine tests of fluoroscopic image quality, a method was developed to quickly and easily measure Wiener spectra (WS) of TV-viewed fluoroscopic systems that considers both spatial and temporal noise correlations. A PC-mounted frame grabber captures images at the TV frame rate to form a three-dimensional (3-D) array of pixels. Scans of a "two-dimensional slit" are then synthesized from which a one-dimensional central section of a 3-D WS is calculated. To avoid errors due to coarse (8-bit) quantization, a video amplifier is used to expand a portion of the signal to the full digitizer range. A reference signal (2 mm of aluminum) is then used to normalize image contrast. Ensemble averages of 250 spectra were obtained in approximately 1 min, including all processing. Results are presented to demonstrate reproducibility, sensitivity, and behavior of the WS. The eventual goal of this work is to use this method in conjunction with measurements of an MTF to calculate fundamental descriptors of image quality, such as SNR and NEQ.

  3. Accuracy of Percutaneous Lumbosacral Pedicle Screw Placement Using the Oblique Fluoroscopic View Based on Computed Tomography Evaluations

    PubMed Central

    Sato, Koji; Kanemura, Tokumi; Iwase, Toshiki; Togawa, Daisuke; Matsuyama, Yukihiro

    2016-01-01

    Study Design Retrospective. Purpose This study aims to investigate the accuracy of the oblique fluoroscopic view, based on preoperative computed tomography (CT) images for accurate placement of lumbosacral percutaneous pedicle screws (PPS). Overview of Literature Although PPS misplacement has been reported as one of the main complications in minimally invasive spine surgery, there is no comparative data on the misplacement rate among different fluoroscopic techniques, or comparing such techniques with open procedures. Methods We retrospectively selected 230 consecutive patients who underwent posterior spinal fusion with a pedicle screw construct for degenerative lumbar disease, and divided them into 3 groups, those who had undergone: minimally invasive percutaneous procedure using biplane (lateral and anterior-posterior views using a single C-arm) fluoroscope views (group M-1), minimally invasive percutaneous procedure using the oblique fluoroscopic view based on preoperative CT (group M-2), and conventional open procedure using a lateral fluoroscopic view (group O: controls). The relative position of the screw to the pedicle was graded for the pedicle breach as no breach, <2 mm, 2–4 mm, or >4 mm. Inaccuracy was calculated and assessed according to the spinal level, direction and neurological deficit. Inter-group radiation exposure was estimated using fluoroscopy time. Results Inaccuracy involved an incline toward L5, causing medial or lateral perforation of pedicles in group M-1, but it was distributed relatively equally throughout multiple levels in groups M-2 and controls. The mean fluoroscopy time/case ranged from 1.6 to 3.9 minutes. Conclusions Minimally invasive lumbosacral PPS placement using the conventional fluoroscopic technique carries an increased risk of inaccurate screw placement and resultant neurological deficits, compared with that of the open procedure. Inaccuracy tended to be distributed between medial and lateral perforations of the L5 pedicle

  4. Visualising uncertainty: Examining women's views on the role of Magnetic Resonance Imaging (MRI) in late pregnancy.

    PubMed

    Reed, Kate; Kochetkova, Inna; Whitby, Elspeth

    2016-09-01

    Prenatal screening occupies a prominent role within sociological debates on medical uncertainty. A particular issue concerns the limitations of routine screening which tends to be based on risk prediction. Computer assisted visual technologies such as Magnetic Resonance Imaging (MRI) are now starting to be applied to the prenatal realm to assist in the diagnosis of a range of fetal and maternal disorders (from problems with the fetal brain to the placenta). MRI is often perceived in popular and medical discourse as a technology of certainty and truth. However, little is known about the use of MRI as a tool to confirm or refute the diagnosis of a range of disorders in pregnancy. Drawing on qualitative research with pregnant women attending a fetal medicine clinic in the North of England this paper examines the potential role that MRI can play in mediating pregnancy uncertainty. The paper will argue that MRI can create and manage women's feelings of uncertainty during pregnancy. However, while MRI may not always provide women with unequivocal answers, the detailed information provided by MR images combined with the interpretation and communication skills of the radiologist in many ways enables women to navigate the issue. Our analysis of empirical data therefore highlights the value of this novel technological application for women and their partners. It also seeks to stress the merit of taking a productive approach to the study of diagnostic uncertainty, an approach which recognises the concepts dual nature.

  5. MRI reporter genes: applications for imaging of cell survival, proliferation, migration and differentiation.

    PubMed

    Vandsburger, Moriel H; Radoul, Marina; Cohen, Batya; Neeman, Michal

    2013-07-01

    Molecular imaging strives to detect molecular events at the level of the whole organism. In some cases, the molecule of interest can be detected either directly or with targeted contrast media. However many genes and proteins and particularly those located in intracellular compartments are not accessible for targeted agents. The transcriptional regulation of these genes can nevertheless be detected, although indirectly, using reporter gene encoding for readily detectable proteins. Such reporter proteins can be expressed in the tissue of interest by genetically introducing the reporter gene in the target cells. Imaging of reporter genes has become a powerful tool in modern biomedical research. Typically, expression of fluorescent and bioluminescent proteins and the reaction product of expressed enzymes and exogenous substrates were examined using in vitro histological methods and in vivo whole body imaging methods. Recent advances in MRI reporter gene methods raised the possibility that MRI could become a powerful tool for concomitant high-resolution anatomical and functional imaging and for imaging of reporter gene activity. An immediate application of MRI reporter gene methods was by monitoring gene expression patterns in gene therapy and in vivo imaging of the survival, proliferation, migration and differentiation of pluripotent and multipotent cells used in cell-based regenerative therapies for cancer, myocardial infarction and neural degeneration. In this review, we characterized a variety of MRI reporter gene methods based on their applicability to report cell survival/proliferation, migration and differentiation. In particular, we discussed which methods were best suited for translation to clinical use in regenerative therapies.

  6. Carotid plaque characterization using CT and MRI scans for synergistic image analysis

    NASA Astrophysics Data System (ADS)

    Getzin, Matthew; Xu, Yiqin; Rao, Arhant; Madi, Saaussan; Bahadur, Ali; Lennartz, Michelle R.; Wang, Ge

    2014-09-01

    Noninvasive determination of plaque vulnerability has been a holy grail of medical imaging. Despite advances in tomographic technologies , there is currently no effective way to identify vulnerable atherosclerotic plaques with high sensitivity and specificity. Computed tomography (CT) and magnetic resonance imaging (MRI) are widely used, but neither provides sufficient information of plaque properties. Thus, we are motivated to combine CT and MRI imaging to determine if the composite information can better reflect the histological determination of plaque vulnerability. Two human endarterectomy specimens (1 symptomatic carotid and 1 stable femoral) were imaged using Scanco Medical Viva CT40 and Bruker Pharmascan 16cm 7T Horizontal MRI / MRS systems. μCT scans were done at 55 kVp and tube current of 70 mA. Samples underwent RARE-VTR and MSME pulse sequences to measure T1, T2 values, and proton density. The specimens were processed for histology and scored for vulnerability using the American Heart Association criteria. Single modality-based analyses were performed through segmentation of key imaging biomarkers (i.e. calcification and lumen), image registration, measurement of fibrous capsule, and multi-component T1 and T2 decay modeling. Feature differences were analyzed between the unstable and stable controls, symptomatic carotid and femoral plaque, respectively. By building on the techniques used in this study, synergistic CT+MRI analysis may provide a promising solution for plaque characterization in vivo.

  7. An exploration of fluoroscopically guided spinal steroid injections in patients with non-specific exercise-related lower-limb pain

    PubMed Central

    Neve, Leon; Orchard, John; Gibbs, Nathan; van Mechelen, Willem; Verhagen, Evert; Sesel, Ken; Burgess, Ian; Hines, Brett

    2010-01-01

    Background Fluoroscopically guided lumbar cortisone injections have been proven useful in cases of lower-limb pain caused by lumbar disc prolapse (with evidence levels ll-1/ll-2). These injections are also sometimes used clinically in sports medicine for patients with non-specific exercise-related lower-limb pain, where no prolapse or other obvious cause of nerve-impingement is diagnosed via magnetic resonance imaging (MRI) or computed tomography (CT), even though this treatment scenario has not been adequately studied for this last diagnosis. Objectives To explore whether fluoroscopically guided transforaminal lumbar cortisone injections may be a valid treatment method for non-specific exercise-related lower-limb pain. Study design Retrospective case series. Methods Patients were selected from databases at two sports clinics and divided into two groups: Group D, with back-related lower-limb pain and disc prolapse proven on CT or MR; and Group N, with non-specific exercise-related lower-limb pain. Patients were sent a questionnaire regarding: symptoms, improvement, effect of injections, satisfaction, side effects and other used treatments. Outcomes were compared between Group D and N. Results 153 patients were eligible for the study (Group D: 93/Group N: 60). Eventually 110 patients responded (Group D: 67/Group N: 43). Twelve percent of Group D and 14% of Group N indicated that the injections had fully cured their symptoms. Altogether, 27% of Group D and 24% of Group N were certain the injections had improved their symptoms in the long term. A larger proportion however, indicated that the injection had certainly improved their symptoms in the short term, but noted that the effects were non-lasting (Group D: 28%/Group N: 30%). Two patients were certain the injections had actually worsened their symptoms. No significant differences in characteristics and outcomes between Group D and Group N were noted. Conclusions Outcomes of this study suggest fluoroscopically

  8. Midbrain and spinal cord magnetic resonance imaging (MRI) changes in poliomyelitis.

    PubMed

    Choudhary, Anita; Sharma, Suvasini; Sankhyan, Naveen; Gulati, Sheffali; Kalra, Veena; Banerjee, Bidisha; Kumar, Atin

    2010-04-01

    Poliomyelitis, though eradicated from most parts of the world, continues to occur in India. There is paucity of data on the magnetic resonance imaging (MRI) changes in poliomyelitis. We report a 3(1/2)-year-old boy who presented with subacute onset flaccid paralysis and altered sensorium. Stool culture was positive for wild polio virus type 3. Magnetic resonance imaging revealed signal changes in bilateral substantia nigra and anterior horns of the spinal cord. These MRI changes may be of potential diagnostic significance in a child with poliomyelitis.

  9. Imaging artifacts induced by electrical stimulation during conventional fMRI of the brain.

    PubMed

    Antal, Andrea; Bikson, Marom; Datta, Abhishek; Lafon, Belen; Dechent, Peter; Parra, Lucas C; Paulus, Walter

    2014-01-15

    Functional magnetic resonance imaging (fMRI) of brain activation during transcranial electrical stimulation is used to provide insight into the mechanisms of neuromodulation and targeting of particular brain structures. However, the passage of current through the body may interfere with the concurrent detection of blood oxygen level-dependent (BOLD) signal, which is sensitive to local magnetic fields. To test whether these currents can affect concurrent fMRI recordings we performed conventional gradient echo-planar imaging (EPI) during transcranial direct current (tDCS) and alternating current stimulation (tACS) on two post-mortem subjects. tDCS induced signals in both superficial and deep structures. The signal was specific to the electrode montage, with the strongest signal near cerebrospinal fluid (CSF) and scalp. The direction of change relative to non-stimulation reversed with tDCS stimulation polarity. For tACS there was no net effect of the MRI signal. High-resolution individualized modeling of current flow and induced static magnetic fields suggested a strong coincidence of the change EPI signal with regions of large current density and magnetic fields. These initial results indicate that (1) fMRI studies of tDCS must consider this potentially confounding interference from current flow and (2) conventional MRI imaging protocols can be potentially used to measure current flow during transcranial electrical stimulation. The optimization of current measurement and artifact correction techniques, including consideration of the underlying physics, remains to be addressed.

  10. 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

  11. Image manifold revealing for breast lesion segmentation in DCE-MRI.

    PubMed

    Hu, Liang; Cheng, Zhaoning; Wang, Manning; Song, Zhijian

    2015-01-01

    Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) is widely used for breast lesion differentiation. Manual segmentation in DCE-MRI is difficult and open to viewer interpretation. In this paper, an automatic segmentation method based on image manifold revealing was introduced to overcome the problems of the currently used method. First, high dimensional datasets were constructed from a dynamic image series. Next, an embedded image manifold was revealed in the feature image by nonlinear dimensionality reduction technique. In the last stage, k-means clustering was performed to obtain final segmentation results. The proposed method was applied in actual clinical cases and compared with the gold standard. Statistical analysis showed that the proposed method achieved an acceptable accuracy, sensitivity, and specificity rates.

  12. Various Imaging Manifestations of Posterior Reversible Encephalopathy Syndrome (PRES) on Magnetic Resonance Imaging (MRI)

    PubMed Central

    Raman, Rajesh; Devaramane, Radhika; Jagadish, Geetha Mukunda; Chowdaiah, Sanjana

    2017-01-01

    Summary Background Posterior reversible encephalopathy syndrome (PRES), also called the acute hypertensive encephalopathy and reversible posterior leukoencephalopathy syndrome (RPLS), is a neurotoxic syndrome of cerebral vasoregulation classically characterized by bilaterally symmetrical parieto-occipital edema. However, the imaging findings are variable and may occur in other locations such as the frontal lobes, thalami, basal ganglia and brainstem. Most commonly, PRES presents with hyperintense signals on T2 and FLAIR sequences. Restricted diffusion and hemorrhage are rare. This study presents the typical and atypical manifestations of PRES on 3T MR images. Material/Methods It is a retrospective study analyzing a radiology report database and MR images of 92 patients with a clinical and radiological diagnosis of PRES. The brain MRI images of these patients were evaluated. The regions involved and the signal intensity of the affected areas on T1, T2, FLAIR and DW sequences were recorded. The location of the abnormal signal intensity as well as the presence or absence of atypical features such as diffusion restriction and hemorrhage were also recorded. Results The most commonly affected region was the parieto-occipital lobes (100%), however, other atypical regions involved were the frontal lobes (30.4%), temporal lobes (8.69%), basal ganglia (22%), cerebellum(17.39%), brainstem(9%) and thalamus(4%). Some of the cases showed restricted diffusion (43%) and hemorrhage (9%). Conclusions The involvement of the parieto-occipital, frontal and temporal lobes is common in PRES. Occasionally, there may be an involvement of the basal ganglia, cerebellum and brainstem, with or without hemorrhage and restricted diffusion. Radiologists should be aware of the typical and atypical imaging manifestations of PRES in order to make an accurate diagnosis. PMID:28243339

  13. Motion Compensated Abdominal Diffusion Weighted MRI by Simultaneous Image Registration and Model Estimation (SIR-ME).

    PubMed

    Kurugol, Sila; Freiman, Moti; Afacan, Onur; Domachevsky, Liran; Perez-Rossello, Jeannette M; Callahan, Michael J; Warfield, Simon K

    2015-01-01

    Non-invasive characterization of water molecule's mobility variations by quantitative analysis of diffusion-weighted MRI (DW-MRI) signal decay in the abdomen has the potential to serve as a biomarker in gastrointestinal and oncological applications. Accurate and reproducible estimation of the signal decay model parameters is challenging due to the presence of respiratory, cardiac, and peristalsis motion. Independent registration of each b-value image to the b-value=0 s/mm(2) image prior to parameter estimation might be sub-optimal because of the low SNR and contrast difference between images of varying b-value. In this work, we introduce a motion-compensated parameter estimation framework that simultaneously solves image registration and model estimation (SIR-ME) problems by utilizing the interdependence of acquired volumes along the diffusion weighting dimension. We evaluated the improvement in model parameters estimation accuracy using 16 in-vivo DW-MRI data sets of Crohn's disease patients by comparing parameter estimates obtained using the SIR-ME model to the parameter estimates obtained by fitting the signal decay model to the acquired DW-MRI images. The proposed SIR-ME model reduced the average root-mean-square error between the observed signal and the fitted model by more than 50%. Moreover, the SIR-ME model estimates discriminate between normal and abnormal bowel loops better than the standard parameter estimates.

  14. Synchronized detection of minute electrical currents with MRI using Lorentz effect imaging

    NASA Astrophysics Data System (ADS)

    Truong, Trong-Kha; Wilbur, Jennifer L.; Song, Allen W.

    2006-03-01

    The blood oxygenation level-dependent (BOLD) effect is the most commonly used contrast mechanism in functional magnetic resonance imaging (fMRI), due to its relatively high spatial resolution and sensitivity. However, the ability of BOLD fMRI to accurately localize neuronal activation in space and time is limited by the inherent hemodynamic modulation. There is hence a need to develop alternative MRI methods that can directly image neuroelectric activity, thereby achieving both a high temporal resolution and spatial specificity as compared to conventional BOLD fMRI. In this paper, we extend the Lorentz effect imaging technique, which can detect spatially incoherent yet temporally synchronized minute electrical activity in a strong magnetic field, and demonstrate its feasibility for imaging randomly oriented electrical currents on the order of microamperes with a temporal resolution on the order of milliseconds in gel phantoms. This constitutes a promising step towards its application to direct imaging of neuroelectric activity in vivo, which has the same order of current density and temporal synchrony.

  15. Potential of PET-MRI for imaging of non-oncologic musculoskeletal disease

    PubMed Central

    Fan, Audrey P.; Gold, Garry E.

    2016-01-01

    Early detection of musculoskeletal disease leads to improved therapies and patient outcomes, and would benefit greatly from imaging at the cellular and molecular level. As it becomes clear that assessment of multiple tissues and functional processes are often necessary to study the complex pathogenesis of musculoskeletal disorders, the role of multi-modality molecular imaging becomes increasingly important. New positron emission tomography-magnetic resonance imaging (PET-MRI) systems offer to combine high-resolution MRI with simultaneous molecular information from PET to study the multifaceted processes involved in numerous musculoskeletal disorders. In this article, we aim to outline the potential clinical utility of hybrid PET-MRI to these non-oncologic musculoskeletal diseases. We summarize current applications of PET molecular imaging in osteoarthritis (OA), rheumatoid arthritis (RA), metabolic bone diseases and neuropathic peripheral pain. Advanced MRI approaches that reveal biochemical and functional information offer complementary assessment in soft tissues. Additionally, we discuss technical considerations for hybrid PET-MR imaging including MR attenuation correction, workflow, radiation dose, and quantification. PMID:28090451

  16. Imaging techniques: MRI illuminated by γ-rays

    NASA Astrophysics Data System (ADS)

    Bowtell, Richard

    2016-09-01

    A technique that combines magnetic resonance with nuclear medicine has been used to image the distribution of a radioactive tracer, potentially opening up a powerful and innovative approach to medical imaging. See Letter p.652

  17. Measurement of Strain in the Left Ventricle during Diastole withcine-MRI and Deformable Image Registration

    SciTech Connect

    Veress, Alexander I.; Gullberg, Grant T.; Weiss, Jeffrey A.

    2005-07-20

    The assessment of regional heart wall motion (local strain) can localize ischemic myocardial disease, evaluate myocardial viability and identify impaired cardiac function due to hypertrophic or dilated cardiomyopathies. The objectives of this research were to develop and validate a technique known as Hyperelastic Warping for the measurement of local strains in the left ventricle from clinical cine-MRI image datasets. The technique uses differences in image intensities between template (reference) and target (loaded) image datasets to generate a body force that deforms a finite element (FE) representation of the template so that it registers with the target image. To validate the technique, MRI image datasets representing two deformation states of a left ventricle were created such that the deformation map between the states represented in the images was known. A beginning diastoliccine-MRI image dataset from a normal human subject was defined as the template. A second image dataset (target) was created by mapping the template image using the deformation results obtained from a forward FE model of diastolic filling. Fiber stretch and strain predictions from Hyperelastic Warping showed good agreement with those of the forward solution. The technique had low sensitivity to changes in material parameters, with the exception of changes in bulk modulus of the material. The use of an isotropic hyperelastic constitutive model in the Warping analyses degraded the predictions of fiber stretch. Results were unaffected by simulated noise down to an SNR of 4.0. This study demonstrates that Warping in conjunction with cine-MRI imaging can be used to determine local ventricular strains during diastole.

  18. MR spectroscopy, functional MRI, and diffusion-tensor imaging in the aging brain: a conceptual review.

    PubMed

    Minati, L; Grisoli, M; Bruzzone, M G

    2007-03-01

    In vivo magnetic resonance spectroscopy (MRS), functional magnetic resonance imaging (fMRI), and diffusion-tensor imaging (DTI) have recently opened new possibilities for noninvasively assessing the metabolic, functional, and connectivity correlates of aging in research and clinical settings. The purpose of this article is to provide a conceptual review intended for a multidisciplinary audience, covering physical principles and main findings related to normal aging and senile cognitive impairment. This article is divided into 3 sections, dedicated to MRS, to fMRI, and to DTI. The spectroscopy section surveys physiological function of the observable metabolites, concentration changes in normal aging and their interpretation, and correlation with cognitive performance. The functional MRI section surveys the hemispheric asymmetry reduction model from compensation and de-differentiation viewpoints, memory encoding, retrieval and consolidation, inhibitory control, perception and action, resting-state networks, and functional deactivations. The DTI section surveys age-related changes, correlation with behavioral scores, and transition to cognitive impairment.

  19. Joint Segmentation of Anatomical and Functional Images: Applications in Quantification of Lesions from PET, PET-CT, MRI-PET, and MRI-PET-CT Images

    PubMed Central

    Bagci, Ulas; Udupa, Jayaram K.; Mendhiratta, Neil; Foster, Brent; Xu, Ziyue; Yao, Jianhua; Chen, Xinjian; Mollura, Daniel J.

    2013-01-01

    We present a novel method for the joint segmentation of anatomical and functional images. Our proposed methodology unifies the domains of anatomical and functional images, represents them in a product lattice, and performs simultaneous delineation of regions based on random walk image segmentation. Furthermore, we also propose a simple yet effective object/background seed localization method to make the proposed segmentation process fully automatic. Our study uses PET, PET-CT, MRI-PET, and fused MRI-PET-CT scans (77 studies in all) from 56 patients who had various lesions in different body regions. We validated the effectiveness of the proposed method on different PET phantoms as well as on clinical images with respect to the ground truth segmentation provided by clinicians. Experimental results indicate that the presented method is superior to threshold and Bayesian methods commonly used in PET image segmentation, is more accurate and robust compared to the other PET-CT segmentation methods recently published in the literature, and also it is general in the sense of simultaneously segmenting multiple scans in real-time with high accuracy needed in routine clinical use. PMID:23837967

  20. The capability of fluoroscopic systems to determine differential Roentgen-ray absorption

    NASA Technical Reports Server (NTRS)

    Baily, N. A.; Crepeau, R. L.

    1975-01-01

    A clinical fluoroscopic unit used in conjunction with a TV image digitization system was investigated to determine its capability to evaluate differential absorption between two areas in the same field. Fractional contrasts and minimum detectability for air, several concentrations of Renografin-60, and aluminum were studied using phantoms of various thicknesses. Results showed that the videometric response, when treated as contrast, shows a linear response with absorber thickness up to considerable thicknesses.

  1. FLUOROSCOPIC EVALUATION OF ORO-PHARYNGEAL DYSPHAGIA: ANATOMY, TECHNIQUE, AND COMMON ETIOLOGIES

    PubMed Central

    Edmund, Dr; Au, Frederick Wing-Fai; Steele, Catriona M.

    2015-01-01

    Target Audience Radiologists and other professionals involved in imaging of oropharyngeal swallowing Objectives To review anatomy of the upper GI tract To review techniques and contrast agents used in the fluoroscopic examination of the oropharynx and hypopharynx To provide a pictorial review of some important causes of oropharyngeal dysphagia, and to link these to key findings in the clinical history to assist in establishing a clinical diagnosis To provide self-assessment questions to reinforce key learning points PMID:25539237

  2. Philips 3T Intera Magnetic Resonance Imaging System and Upgrade of existing MRI equipment

    SciTech Connect

    Evanochko, William T

    2004-05-14

    The objective of this proposal was twofold. First, upgrade existing MRI equipment, specifically a research 4.1T whole-body system. Second, purchase a clinical, state-of-the-art 3T MRI system tailored specifically to cardiovascular and neurological applications. This project was within the guidelines of ''Medical Applications and Measurement Science''. The goals were: [1] to develop beneficial applications of magnetic resonance imaging; [2] discover new applications of MR strategies for medical research; and [2] apply them for clinical diagnosis. Much of this proposal searched for breakthroughs in this noninvasive and nondestructive imaging technology. Finally, this proposal's activities focused on research in the basic science of chemistry, biochemistry, physics, and engineering as applied to bioengineering. The centerpiece of this grant was our 4.1T ultra-high field whole-body nuclear magnetic resonance system and the newly acquired state-of-the-art, heart and head dedicated 3T clinical MRI system. We have successfully upgraded the equipment for the 4.1T system so that it is now state-of-the-art with new gradient and radio frequency amplifiers. We also purchase a unique In Vivo EKG monitoring unit that will permit tracking clinical quality EKG signals while the patient is in a high field MR scanner. Important upgrades of a peripheral vascular coil and a state-of-the-art clinical workstation for processing complex heart images were implemented. The most recent acquisition was the purchase of a state-of-the-art Philips 3T Intera clinical MRI system. This system is unique in that the magnet is only 5 1/2 feet long compare to over 12 feet long magnet of our 4.1T MRI system. The 3T MRI system is fully functional and its use and applications are already greatly benefiting the UAB with 200-300 micron resolution brain images and diagnostic quality MR angiography of coronary arteries in less than 5 minutes.

  3. The Iowa Gambling Task in fMRI Images

    PubMed Central

    Li, Xiangrui; Lu, Zhong-Lin; D'Argembeau, Arnaud; Ng, Marie; Bechara, Antoine

    2009-01-01

    The Iowa Gambling Task (IGT) is a sensitive test for the detection of decision-making impairments in several neurologic and psychiatric populations. Very few studies have employed the IGT in fMRI investigations, in part, because the task is cognitively complex. Here we report a method for exploring brain activity using fMRI during performance of the IGT. Decision-making during the IGT was associated with activity in several brain regions in a group of healthy individuals. The activated regions were consistent with the neural circuitry hypothesized to underlie somatic marker activation and decision-making. Specifically, a neural circuitry involving the dorsolateral prefrontal cortex (for working memory), the insula and posterior cingulate cortex (for representations of emotional states), the mesial orbitofrontal and ventromedial prefrontal cortex (for coupling the two previous processes), the ventral striatum and anterior cingulate/SMA (supplementary motor area) for implementing behavioral decisions was engaged. These results have implications for using the IGT to study abnormal mechanisms of decision making in a variety of clinical populations. PMID:19777556

  4. Optimal sampling with prior information of the image geometry in microfluidic MRI.

    PubMed

    Han, S H; Cho, H; Paulsen, J L

    2015-03-01

    Recent advances in MRI acquisition for microscopic flows enable unprecedented sensitivity and speed in a portable NMR/MRI microfluidic analysis platform. However, the application of MRI to microfluidics usually suffers from prolonged acquisition times owing to the combination of the required high resolution and wide field of view necessary to resolve details within microfluidic channels. When prior knowledge of the image geometry is available as a binarized image, such as for microfluidic MRI, it is possible to reduce sampling requirements by incorporating this information into the reconstruction algorithm. The current approach to the design of the partial weighted random sampling schemes is to bias toward the high signal energy portions of the binarized image geometry after Fourier transformation (i.e. in its k-space representation). Although this sampling prescription is frequently effective, it can be far from optimal in certain limiting cases, such as for a 1D channel, or more generally yield inefficient sampling schemes at low degrees of sub-sampling. This work explores the tradeoff between signal acquisition and incoherent sampling on image reconstruction quality given prior knowledge of the image geometry for weighted random sampling schemes, finding that optimal distribution is not robustly determined by maximizing the acquired signal but from interpreting its marginal change with respect to the sub-sampling rate. We develop a corresponding sampling design methodology that deterministically yields a near optimal sampling distribution for image reconstructions incorporating knowledge of the image geometry. The technique robustly identifies optimal weighted random sampling schemes and provides improved reconstruction fidelity for multiple 1D and 2D images, when compared to prior techniques for sampling optimization given knowledge of the image geometry.

  5. Functional Cardiac Magnetic Resonance Imaging (MRI) in the Assessment of Myocardial Viability and Perfusion

    PubMed Central

    2003-01-01

    Executive Summary Objective The objective of this health technology policy assessment was to determine the effectiveness safety and cost-effectiveness of using functional cardiac magnetic resonance imaging (MRI) for the assessment of myocardial viability and perfusion in patients with coronary artery disease and left ventricular dysfunction. Results Functional MRI has become increasingly investigated as a noninvasive method for assessing myocardial viability and perfusion. Most patients in the published literature have mild to moderate impaired LV function. It is possible that the severity of LV dysfunction may be an important factor that can alter the diagnostic accuracy of imaging techniques. There is some evidence of comparable or better performance of functional cardiac MRI for the assessment of myocardial viability and perfusion compared with other imaging techniques. However limitations to most of the studies included: Functional cardiac MRI studies that assess myocardial viability and perfusion have had small sample sizes. Some studies assessed myocardial viability/perfusion in patients who had already undergone revascularization, or excluded patients with a prior MI (Schwitter et al., 2001). Lack of explicit detail of patient recruitment. Patients with LVEF >35%. Interstudy variability in post MI imaging time(including acute or chronic MI), when patients with a prior MI were included. Poor interobserver agreement (kappa statistic) in the interpretation of the results. Traditionally, 0.80 is considered “good”. Cardiac MRI measurement of myocardial perfusion to as an adjunct tool to help diagnose CAD (prior to a definitive coronary angiography) has also been examined in some studies, with methodological limitations, yielding comparable results. Many studies examining myocardial viability and perfusion report on the accuracy of imaging methods with limited data on long-term patient outcome and management. Kim et al. (2000) revealed that the transmural

  6. Comparison of CT and MRI brain tumor imaging using a canine glioma model.

    PubMed

    Whelan, H T; Clanton, J A; Wilson, R E; Tulipan, N B

    1988-01-01

    A canine gliosarcoma model was used to study the effectiveness of magnetic resonance imaging (MRI) with gadolinium contrast enhancement in defining the histologic margins of brain tumors. The effectiveness of this technique was compared to conventional computed tomography (CT) using iodinated contrast enhancement. Cultured canine gliosarcoma cells were injected into the left hemisphere of adult mongrel dogs. The dogs developed brain tumors and progressive clinical signs. Serial MRI with and without gadolinium diethylene triamine penta-acetic acid was compared to serial CT with and without sodium iothalamate obtained on the same days. After the final scans, animals were sacrificed; the brains were removed and processed for routine histopathologic study. All tumors were visualized with contrast-enhanced MRI which proved most sensitive. Gadolinium di-ethylene triamine penta-acetic acid caused bright enhancement of tumors in a distribution that consistently corresponded to areas of pathologically proved tumor infiltration. Gross and microscopic autopsy findings correlated better with MRI than with CT which tended to produce poorer resolution and underrepresent the size of viable tumor. Gadolinium-enhanced MRI is more accurate than unenhanced MRI, unenhanced CT, or enhanced CT in defining the histologic margins of tumors.

  7. Investigating the feasibility of rapid MRI for image-guided motion management in lung cancer radiotherapy.

    PubMed

    Sawant, Amit; Keall, Paul; Pauly, Kim Butts; Alley, Marcus; Vasanawala, Shreyas; Loo, Billy W; Hinkle, Jacob; Joshi, Sarang

    2014-01-01

    Cycle-to-cycle variations in respiratory motion can cause significant geometric and dosimetric errors in the administration of lung cancer radiation therapy. A common limitation of the current strategies for motion management is that they assume a constant, reproducible respiratory cycle. In this work, we investigate the feasibility of using rapid MRI for providing long-term imaging of the thorax in order to better capture cycle-to-cycle variations. Two nonsmall-cell lung cancer patients were imaged (free-breathing, no extrinsic contrast, and 1.5 T scanner). A balanced steady-state-free-precession (b-SSFP) sequence was used to acquire cine-2D and cine-3D (4D) images. In the case of Patient 1 (right midlobe lesion, ~40 mm diameter), tumor motion was well correlated with diaphragmatic motion. In the case of Patient 2, (left upper-lobe lesion, ~60 mm diameter), tumor motion was poorly correlated with diaphragmatic motion. Furthermore, the motion of the tumor centroid was poorly correlated with the motion of individual points on the tumor boundary, indicating significant rotation and/or deformation. These studies indicate that image quality and acquisition speed of cine-2D MRI were adequate for motion monitoring. However, significant improvements are required to achieve comparable speeds for truly 4D MRI. Despite several challenges, rapid MRI offers a feasible and attractive tool for noninvasive, long-term motion monitoring.

  8. [Application of pharmacologic functional magnetic resonance imaging (phMRI) in the research of affective disorders].

    PubMed

    Édes, Andrea Edit; Gonda, Xénia; Bagdy, György; Juhász, Gabriella

    2014-06-01

    Many common psychiatric disorders such as depression and anxiety disorders are associated with dysfunction in the monoamine neurotransmission in the central nervous system. However, the investigation of these pathophysiological processes in the human living brain is difficult. In case of functional magnetic resonance imaging (fMRI), a non-invasive method for the examination of brain activity, the activity-inducing stimulus is generally a cognitive psychological test, while during pharmacological magnetic resonance imaging (phMRI) the activation is triggered by a specific pharmacon. In the present work we review the available scientific literature related to this method using literature search in PubMed. Through application of a selective pharmacon like the selective serotonine reuptake inhibitors (SSRIs) citalopram or escitalopram in a challenge phMRI study, the serotonergic neurotransmitter system can be examined specifically, the functioning brain areas involved in its effect become observable.. With modulation phMRI we can monitor the long-term effect of an antidepressant or we can examine the immediate effect of a single dose of the medication on congitive psychological functions like emotional processing. Thus, the application of phMRI methods may help deepen our understanding of serotonergic function in the living human brain as well as of diseases related to serotonergic neurotransmitter system dysfunction.

  9. Advantage of Adding Diffusion Weighted Imaging to Routine MRI Examinations in the Diagnostics of Scrotal Lesions

    PubMed Central

    Algebally, Ahmed Mohamed; Tantawy, Hazim Ibrahim; Yousef, Reda Ramadan Hussein; Szmigielski, Wojciech; Darweesh, Adham

    2015-01-01

    Summary Background The purpose of the study is to identify the diagnostic value of adding diffusion weighted images (DWI) to routine MRI examinations of the scrotum. Material/Methods The study included 100 testes of 50 patients with a unilateral testicular disease. Fifty normal contralateral testes were used as a control group. All patients underwent conventional MRI and DWI examinations of the scrotum. The results of MRI and DWI of the group of patients treated surgically were correlated with histopathological findings. The MRI and DWI results of non-surgical cases were correlated with the results of clinical, laboratory and other imaging studies. Comparison of the ADC value of normal and pathological tissues was carried out followed by a statistical analysis. Results There was a significant difference between ADC values of malignant testicular lesions and normal testicular tissues as well as benign testicular lesions (P=0.000). At a cut-off ADC value of ≤0.99, it had a sensitivity of 93.3%, specificity of 90%, positive predictive value of 87.5%, and negative predictive value of 94.7% in the characterization of intratesticular masses. Conclusions Inclusion of DWI to routine MRI has a substantial value in improving diagnosis in patients with scrotal lesions and consequently can reduce unnecessary radical surgical procedures in these patients. PMID:26491491

  10. Neonatal brain image segmentation in longitudinal MRI studies.

    PubMed

    Shi, Feng; Fan, Yong; Tang, Songyuan; Gilmore, John H; Lin, Weili; Shen, Dinggang

    2010-01-01

    In the study of early brain development, tissue segmentation of neonatal brain MR images remains challenging because of the insufficient image quality due to the properties of developing tissues. Among various brain tissue segmentation algorithms, atlas-based brain image segmentation can potentially achieve good segmentation results on neonatal brain images. However, their performances rely on both the quality of the atlas and the spatial correspondence between the atlas and the to-be-segmented image. Moreover, it is difficult to build a population atlas for neonates due to the requirement of a large set of tissue-segmented neonatal brain images. To combat these obstacles, we present a longitudinal neonatal brain image segmentation framework by taking advantage of the longitudinal data acquired at late time-point to build a subject-specific tissue probabilistic atlas. Specifically, tissue segmentation of the neonatal brain is formulated as two iterative steps of bias correction and probabilistic-atlas-based tissue segmentation, along with the longitudinal atlas reconstructed by the late time image of the same subject. The proposed method has been evaluated qualitatively through visual inspection and quantitatively by comparing with manual delineations and two population-atlas-based segmentation methods. Experimental results show that the utilization of a subject-specific probabilistic atlas can substantially improve tissue segmentation of neonatal brain images.

  11. Registration of 2D x-ray images to 3D MRI by generating pseudo-CT data

    NASA Astrophysics Data System (ADS)

    van der Bom, M. J.; Pluim, J. P. W.; Gounis, M. J.; van de Kraats, E. B.; Sprinkhuizen, S. M.; Timmer, J.; Homan, R.; Bartels, L. W.

    2011-02-01

    Spatial and soft tissue information provided by magnetic resonance imaging can be very valuable during image-guided procedures, where usually only real-time two-dimensional (2D) x-ray images are available. Registration of 2D x-ray images to three-dimensional (3D) magnetic resonance imaging (MRI) data, acquired prior to the procedure, can provide optimal information to guide the procedure. However, registering x-ray images to MRI data is not a trivial task because of their fundamental difference in tissue contrast. This paper presents a technique that generates pseudo-computed tomography (CT) data from multi-spectral MRI acquisitions which is sufficiently similar to real CT data to enable registration of x-ray to MRI with comparable accuracy as registration of x-ray to CT. The method is based on a k-nearest-neighbors (kNN)-regression strategy which labels voxels of MRI data with CT Hounsfield Units. The regression method uses multi-spectral MRI intensities and intensity gradients as features to discriminate between various tissue types. The efficacy of using pseudo-CT data for registration of x-ray to MRI was tested on ex vivo animal data. 2D-3D registration experiments using CT and pseudo-CT data of multiple subjects were performed with a commonly used 2D-3D registration algorithm. On average, the median target registration error for registration of two x-ray images to MRI data was approximately 1 mm larger than for x-ray to CT registration. The authors have shown that pseudo-CT data generated from multi-spectral MRI facilitate registration of MRI to x-ray images. From the experiments it could be concluded that the accuracy achieved was comparable to that of registering x-ray images to CT data.

  12. [From anatomy to image: the cranial nerves at MRI].

    PubMed

    Conforti, Renata; Marrone, Valeria; Sardaro, Angela; Faella, Pierluigi; Grassi, Roberta; Cappabianca, Salvatore

    2013-01-01

    In this article, we review the expected course of each of the 12 cranial nerves. Traditional magnetic resonance imaging depicts only the larger cranial nerves but SSFP sequences of magnetic resonance imaging are capable of depicting the cisternal segments of 12 cranial nerves and also provide submillimetric spatial resolution.

  13. MRI image characteristics of materials implanted at sellar region after transsphenoidal resection of pituitary tumours

    PubMed Central

    Bladowska, Joanna; Bednarek-Tupikowska, Grażyna; Sokolska, Violetta; Badowski, Roman; Moroń, Krzysztof; Bonicki, Wiesław; Sąsiadek, Marek

    2010-01-01

    Summary Background: Post-surgical evaluation of the pituitary gland in MRI is difficult because of a change in anatomical conditions. It depends also on numerous other factors, including: size and expansion of the tumour before surgery, type of surgical access, quality and volume of implanted materials and time of its resorption. The purpose was to demonstrate the characteristics of the implanted materials on MRI performed after transsphenoidal resection of pituitary tumours and to identify imaging criteria helpful in differential diagnosis of masses within the sellar region. Material/Methods: One hundred and fifty-four patients after transsphenoidal resection of pituitary tumours were included in the study. In general, 469 MRI examinations were performed with a 1.5T scanner. We obtained T1-weighted sagittal and coronal, enhanced and unenhanced images. In 102 cases, additional T2-weighted coronal, unenhanced images with 1.5 T unit were obtained as well. Results: The implanted materials appeared in 95 patient: fat in 86 and muscle with fascia in 3 patients. We could recognise implanted muscle and fascia in T2-weighted images, because of high signal intensity of the degenerating muscle and the line of low signal representing fascia. The implanted titanium mesh was found in 4 patients. Haemostatic materials were visible only in 2 patients in examinations performed at an early postoperative stage (1 month after the procedure). Conclusions: The knowledge of MRI characteristics of the materials implanted at the sellar region is very important in postoperative diagnosis of pituitary tumours and may help discriminate between tumorous and non-tumorous involvement of the sellar region. Some implanted materials, like fat, could be seen on MRI for as long as 10 years after the operation, others, like haemostatic materials, for only 1 month after surgery. T2-weighted imaging is a useful assessment method of the implanted muscle and fascia for a long time after surgery. PMID

  14. Activatable molecular MRI nanoprobe for tumor cell imaging based on gadolinium oxide and iron oxide nanoparticle.

    PubMed

    Li, Jingjing; Wang, Shan; Wu, Chen; Dai, Yue; Hou, Pingfu; Han, Cuiping; Xu, Kai

    2016-12-15

    Activatable molecular MRI nanoprobe for intracellular GSH sensing was designed. As an alternative to "always on" nanoprobe, activatable imaging nanoprobes which are designed to amplify or boost imaging signals only in response to the targets have attracted more and more attention. In this paper, we designed a novel activatable molecular magnetic resonance imaging (MRI) nanoprobe for tumor cell recognization based on a MRI signal variation induced by the distance change between T1 and T2 contrast agents (CAs) in the presence of glutathione (GSH). To achieve this aim, carboxyl group functionalized iron oxide nanoparticles (Fe3O4 NPs) and polyethylene glycol-coated gadolinium oxide (PEG-Gd2O3) NPs as T2 and T1 MRI CA were connected by cystamine which contains a disulfide linkage. Transmission electron microscopic (TEM), X-ray photoelectron spectroscopy (XPS), energy dispersive spectrometer (EDS), fourier transform infrared spectroscopy (FT-IR), mass spectra and (1)H nuclear magnetic resonance spectroscopy ((1)H NMR) were introduced for their characterizations. The formation of Fe3O4-cystamine-Gd2O3 (Fe3O4-SS-Gd2O3) nanocomplex resulted in a quenched T1 signal due to the near proximity of PEG-Gd2O3 NPs to Fe3O4 NPs and a "light-up" T1 signal with the cleavage of disulfide bond in the presence of GSH. These results provide not only an easy way to realize MRI of tumor cells based on the overexpressed intracellular GSH level, but also a new insight for the design of activatable MRI nanoprobe.

  15. Digital Subtraction Fluoroscopic System With Tandem Video Processing Units

    NASA Astrophysics Data System (ADS)

    Gould, Robert G.; Lipton, Martin J.; Mengers, Paul; Dahlberg, Roger

    1981-07-01

    A real-time digital fluoroscopic system utilizing two video processing units (Quantex) in tandem to produce continuous subtraction images of peripheral and internal vessels following intravenous contrast media injection has been inves-tigated. The first processor subtracts a mask image consisting of an exponentially weighted moving average of N1 frames (N1 = 2k where k = 0.7) from each incoming video frame, divides by N1, and outputs the resulting difference image to the second processor. The second unit continuously averages N2 incoming frames (N2 = 2k) and outputs to a video monitor and analog disc recorder. The contrast of the subtracted images can be manipulated by changing gain or by a non-linear output transform. After initial equipment adjustments, a subtraction sequence can be produced without operator interaction with the processors. Alternatively, the operator can freeze the mask and/or the subtracted output image at any time during the sequence. Raw data is preserved on a wide band video tape recorder permitting retrospective viewing of an injection sequence with different processor settings. The advantage of the tandem arrangement is that it has great flexibility in varying the duration and the time of both the mask and injection images thereby minimizing problems of registration between them. In addition, image noise is reduced by compiling video frames rather than by using a large radiation dose for a single frame, which requires a wide dynamic range video camera riot commonly available in diagnostic x-ray equipment. High quality subtraction images of arteries have been obtained in 15 anesthetized dogs using relatively low exposure rates (10-12 μR/video frame) modest volumes of contrast medium (0.5-1 ml/kg), and low injection flow rates (6-10 ml/sec). The results/ achieved so far suggest that this system has direct clinical applications.

  16. An Atlas-Based Electron Density Mapping Method for Magnetic Resonance Imaging (MRI)-Alone Treatment Planning and Adaptive MRI-Based Prostate Radiation Therapy

    SciTech Connect

    Dowling, Jason A.; Lambert, Jonathan; Parker, Joel; Salvado, Olivier; Fripp, Jurgen; Capp, Anne; Wratten, Chris; Denham, James W.; Greer, Peter B.

    2012-05-01

    Purpose: Prostate radiation therapy dose planning directly on magnetic resonance imaging (MRI) scans would reduce costs and uncertainties due to multimodality image registration. Adaptive planning using a combined MRI-linear accelerator approach will also require dose calculations to be performed using MRI data. The aim of this work was to develop an atlas-based method to map realistic electron densities to MRI scans for dose calculations and digitally reconstructed radiograph (DRR) generation. Methods and Materials: Whole-pelvis MRI and CT scan data were collected from 39 prostate patients. Scans from 2 patients showed significantly different anatomy from that of the remaining patient population, and these patients were excluded. A whole-pelvis MRI atlas was generated based on the manually delineated MRI scans. In addition, a conjugate electron-density atlas was generated from the coregistered computed tomography (CT)-MRI scans. Pseudo-CT scans for each patient were automatically generated by global and nonrigid registration of the MRI atlas to the patient MRI scan, followed by application of the same transformations to the electron-density atlas. Comparisons were made between organ segmentations by using the Dice similarity coefficient (DSC) and point dose calculations for 26 patients on planning CT and pseudo-CT scans. Results: The agreement between pseudo-CT and planning CT was quantified by differences in the point dose at isocenter and distance to agreement in corresponding voxels. Dose differences were found to be less than 2%. Chi-squared values indicated that the planning CT and pseudo-CT dose distributions were equivalent. No significant differences (p > 0.9) were found between CT and pseudo-CT Hounsfield units for organs of interest. Mean {+-} standard deviation DSC scores for the atlas-based segmentation of the pelvic bones were 0.79 {+-} 0.12, 0.70 {+-} 0.14 for the prostate, 0.64 {+-} 0.16 for the bladder, and 0.63 {+-} 0.16 for the rectum

  17. MRI Mode Programming for Safe Magnetic Resonance Imaging in Patients With a Magnetic Resonance Conditional Cardiac Device.

    PubMed

    Nakai, Toshiko; Kurokawa, Sayaka; Ikeya, Yukitoshi; Iso, Kazuki; Takahashi, Keiko; Sasaki, Naoko; Ashino, Sonoko; Okubo, Kimie; Okumura, Yasuo; Kunimoto, Satoshi; Watanabe, Ichiro; Hirayama, Atsushi

    2016-01-01

    Although diagnostically indispensable, magnetic resonance imaging (MRI) has been, until recently, contraindicated in patients with an implantable cardiac device. MR conditional cardiac devices are now widely used, but the mode programming needed for safe MRI has yet to be established. We reviewed the details of 41 MRI examinations of patients with a MR conditional device. There were no associated adverse events. However, in 3 cases, paced beats competed with the patient's own beats during the MRI examination. We describe 2 of the 3 specific cases because they illustrate these potentially risky situations: a case in which the intrinsic heart rate increased and another in which atrial fibrillation occurred. Safe MRI in patients with an MR conditional device necessitates detailed MRI mode programming. The MRI pacing mode should be carefully and individually selected.

  18. Synergistic role of simultaneous PET/MRI-MRS in soft tissue sarcoma metabolism imaging.

    PubMed

    Zhang, Xiaomeng; Chen, Yen-Lin E; Lim, Ruth; Huang, Chuan; Chebib, Ivan A; El Fakhri, Georges

    2016-04-01

    The primary objective of this study was to develop and validate simultaneous PET/MRI-MRS as a novel biological image-guided approach to neoadjuvant radiotherapy (RT) and/or chemoradiation (chemoRT) in soft tissue sarcomas (STS). A patient with sarcoma of the right thigh underwent PET/MRI scan before and after neoadjuvant (preoperative) radiotherapy. The magnetic resonance imaging (MRI) and 2-deoxy-2-[fluorine-18]-fluoro-D-glucose-Positron Emission Tomography ((18)F-FDG-PET) scans were performed simultaneously. In the post-radiation scan, magnetic resonance spectroscopy (MRS) was subsequently acquired with volume of interest positioned in a residual hyper-metabolic region detected by PET. Post-radiation PET/MRI showed a residual T2-hyperintense mass with significantly reduced (18)F-FDG-uptake, compatible with near complete response to radiotherapy. However, a small region of residual high (18)F-FDG uptake was detected at the tumor margin. MRS of this region had similar metabolite profile as normal tissue, and was thus considered false positive on PET scan. Pathology results were obtained after surgery for confirmation of imaging findings.

  19. Real-time 3D imaging of microstructure growth in battery cells using indirect MRI

    PubMed Central

    Ilott, Andrew J.; Mohammadi, Mohaddese; Chang, Hee Jung; Grey, Clare P.; Jerschow, Alexej

    2016-01-01

    Lithium metal is a promising anode material for Li-ion batteries due to its high theoretical specific capacity and low potential. The growth of dendrites is a major barrier to the development of high capacity, rechargeable Li batteries with lithium metal anodes, and hence, significant efforts have been undertaken to develop new electrolytes and separator materials that can prevent this process or promote smooth deposits at the anode. Central to these goals, and to the task of understanding the conditions that initiate and propagate dendrite growth, is the development of analytical and nondestructive techniques that can be applied in situ to functioning batteries. MRI has recently been demonstrated to provide noninvasive imaging methodology that can detect and localize microstructure buildup. However, until now, monitoring dendrite growth by MRI has been limited to observing the relatively insensitive metal nucleus directly, thus restricting the temporal and spatial resolution and requiring special hardware and acquisition modes. Here, we present an alternative approach to detect a broad class of metallic dendrite growth via the dendrites’ indirect effects on the surrounding electrolyte, allowing for the application of fast 3D 1H MRI experiments with high resolution. We use these experiments to reconstruct 3D images of growing Li dendrites from MRI, revealing details about the growth rate and fractal behavior. Radiofrequency and static magnetic field calculations are used alongside the images to quantify the amount of the growing structures. PMID:27621444

  20. MRI in Dentistry- A Future Towards Radiation Free Imaging – Systematic Review

    PubMed Central

    Patthi, Basavaraj; Singla, Ashish; Gupta, Ritu; Ali, Irfan; Dhama, Kuldeep; Kumar, Jishnu Krishna; Prasad, Monika

    2016-01-01

    Introduction Magnetic Resonance Imaging (MRI), being a technique with huge potential, has become the primary diagnostic investigation for many clinical problems. Its application now has been successfully used in dentistry to maximize the diagnostic certainty. Aim The present review aims to analyze the applicability, feasibility and efficacy of MRI in the field of dentistry. Materials and Methods A literature search was performed in main databases like Pub Med Central, Cochrane Library, Embase and Google Scholar from 1970 up to December 2015. The 2672 titles that appeared, 25 fulfilled the criteria and were included in the review. Two articles were hand searched and three articles through e-mail were also included. Results The review highlights the increasing role of MRI in dentistry. In the available literature, it was found that T1 and T2 weighted images were the acceptable diagnostic images for detection of dental related diseases. Conclusion MRI can be used in diagnosis and treatment planning of implants, jaw lesions, diseases of Temporomandibular Joints (TMJ), orthodontic treatment, endodontic treatment etc., to achieve better prognosis. PMID:27891491

  1. A small, battery-operated fluoroscopic system - Lixiscope with X-ray generator

    NASA Technical Reports Server (NTRS)

    Yin, L. I.; Trombka, J. I.; Ruitberg, A. P.; Seltzer, S. M.

    1983-01-01

    A small, battery-operated X-ray generator has been developed to be used as part of a small-format fluoroscopic system, the Lixiscope (Low Intensity X-ray Imaging Scope). The X-ray generator consists of a grounded rod-anode X-ray tube with a 0.2 mm focal spot and a specially designed, battery-operated, 0 to -80 kV high-voltge supply. Total power consumption is about 10 W. The fine focal spot, in conjunction with the continuously variable X-ray intensity and spectral distribution, helps to extend both the versatility and the performance of the Lixiscope toward a much wider range of terrestrial and spacecraft applications. The complete fluoroscopic system is described, and some examples of possible applications are shown.

  2. Visualization of human prenatal development by magnetic resonance imaging (MRI).

    PubMed

    Shiota, Kohei; Yamada, Shigehito; Nakatsu-Komatsu, Tomoko; Uwabe, Chigako; Kose, Katsumi; Matsuda, Yoshimasa; Haishi, Tomoyuki; Mizuta, Shinobu; Matsuda, Tetsuya

    2007-12-15

    It is essential to visualize the structures of embryos and their internal organs three-dimensionally to analyze morphogenesis; this used to rely solely on serial histological sectioning and solid reconstruction, which were tedious and time-consuming. We have applied imaging with a magnetic resonance (MR) microscope equipped with a 2.35 T superconducting magnet to visualize human embryos; we were successful in acquiring high-resolution sectional images and in identifying the detailed structures of major organs. The imaging process was facilitated by using a super-parallel MR microscope. A dataset of MR images of more than 1,000 human embryos, now collected, will be important for future biomedical research and for education.

  3. Four-dimensional magnetic resonance imaging (4D-MRI) using image-based respiratory surrogate: A feasibility study

    PubMed Central

    Cai, Jing; Chang, Zheng; Wang, Zhiheng; Paul Segars, William; Yin, Fang-Fang

    2011-01-01

    Purpose: Four-dimensional computed tomography (4D-CT) has been widely used in radiation therapy to assess patient-specific breathing motion for determining individual safety margins. However, it has two major drawbacks: low soft-tissue contrast and an excessive imaging dose to the patient. This research aimed to develop a clinically feasible four-dimensional magnetic resonance imaging (4D-MRI) technique to overcome these limitations. Methods: The proposed 4D-MRI technique was achieved by continuously acquiring axial images throughout the breathing cycle using fast 2D cine-MR imaging, and then retrospectively sorting the images by respiratory phase. The key component of the technique was the use of body area (BA) of the axial MR images as an internal respiratory surrogate to extract the breathing signal. The validation of the BA surrogate was performed using 4D-CT images of 12 cancer patients by comparing the respiratory phases determined using the BA method to those determined clinically using the Real-time position management (RPM) system. The feasibility of the 4D-MRI technique was tested on a dynamic motion phantom, the 4D extended Cardiac Torso (XCAT) digital phantom, and two healthy human subjects. Results: Respiratory phases determined from the BA matched closely to those determined from the RPM: mean (±SD) difference in phase: −3.9% (±6.4%); mean (±SD) absolute difference in phase: 10.40% (±3.3%); mean (±SD) correlation coefficient: 0.93 (±0.04). In the motion phantom study, 4D-MRI clearly showed the sinusoidal motion of the phantom; image artifacts observed were minimal to none. Motion trajectories measured from 4D-MRI and 2D cine-MRI (used as a reference) matched excellently: the mean (±SD) absolute difference in motion amplitude: −0.3 (±0.5) mm. In the 4D-XCAT phantom study, the simulated “4D-MRI” images showed good consistency with the original 4D-XCAT phantom images. The motion trajectory of the hypothesized “tumor” matched

  4. Image homogenization using pre-emphasis method for high field MRI.

    PubMed

    Li, Ye; Wang, Chunsheng; Yu, Baiying; Vigneron, Daniel; Chen, Wei; Zhang, Xiaoliang

    2013-08-01

    Radiofrequency (RF) field (B 1) inhomogeneity due to shortened wavelength at high field is a major cause of magnetic resonance imaging (MRI) nonuniformity in high dielectric biological samples (e.g., human body). In this work, we propose a method to improve the B 1 and MRI homogeneity by using pre-emphasized non-uniform B 1 distribution. The intrinsic B 1 distribution that could be generated by a RF volume coil, specifically a microstrip transmission line (MTL) coil used in this work, was pre-emphasized in the sample's periphery region of interest to compensate for the central brightness induced by high frequency interference effect due to shortened wave length. This pre-emphasized non-uniform B 1 can be realized by varying the parameters of microstrip elements, such as the substrate thickness of MTL volume coil. Both numerical simulation and phantom MR imaging studies were carried out to investigate the feasibility and merit of the proposed method in achieving homogeneous MR images. The simulation results demonstrate that by using a pre-emphasized B 1 distribution generated by the MTL volume coil, relatively uniform B 1 distribution and homogeneous MR image (98% homogeneity) within the spherical phantom (15 cm diameter) were achieved with 4.5 mm thickness. The B 1 and MRI intensity distributions of a 16-element MTL volume coil with fixed substrate thickness and five varied saline loads were modeled and experimentally tested. Similar results from both simulation and experiments were obtained, suggesting substantial improvements of B 1 and MRI homogeneities within the phantom containing 125 mM saline. The overall results demonstrate an efficient B 1 shimming approach for improving high field MRI.

  5. Quantitative evaluation of brain development using anatomical MRI and diffusion tensor imaging.

    PubMed

    Oishi, Kenichi; Faria, Andreia V; Yoshida, Shoko; Chang, Linda; Mori, Susumu

    2013-11-01

    The development of the brain is structure-specific, and the growth rate of each structure differs depending on the age of the subject. Magnetic resonance imaging (MRI) is often used to evaluate brain development because of the high spatial resolution and contrast that enable the observation of structure-specific developmental status. Currently, most clinical MRIs are evaluated qualitatively to assist in the clinical decision-making and diagnosis. The clinical MRI report usually does not provide quantitative values that can be used to monitor developmental status. Recently, the importance of image quantification to detect and evaluate mild-to-moderate anatomical abnormalities has been emphasized because these alterations are possibly related to several psychiatric disorders and learning disabilities. In the research arena, structural MRI and diffusion tensor imaging (DTI) have been widely applied to quantify brain development of the pediatric population. To interpret the values from these MR modalities, a "growth percentile chart," which describes the mean and standard deviation of the normal developmental curve for each anatomical structure, is required. Although efforts have been made to create such a growth percentile chart based on MRI and DTI, one of the greatest challenges is to standardize the anatomical boundaries of the measured anatomical structures. To avoid inter- and intra-reader variability about the anatomical boundary definition, and hence, to increase the precision of quantitative measurements, an automated structure parcellation method, customized for the neonatal and pediatric population, has been developed. This method enables quantification of multiple MR modalities using a common analytic framework. In this paper, the attempt to create an MRI- and a DTI-based growth percentile chart, followed by an application to investigate developmental abnormalities related to cerebral palsy, Williams syndrome, and Rett syndrome, have been introduced. Future

  6. Reprint of "Quantitative evaluation of brain development using anatomical MRI and diffusion tensor imaging".

    PubMed

    Oishi, Kenichi; Faria, Andreia V; Yoshida, Shoko; Chang, Linda; Mori, Susumu

    2014-02-01

    The development of the brain is structure-specific, and the growth rate of each structure differs depending on the age of the subject. Magnetic resonance imaging (MRI) is often used to evaluate brain development because of the high spatial resolution and contrast that enable the observation of structure-specific developmental status. Currently, most clinical MRIs are evaluated qualitatively to assist in the clinical decision-making and diagnosis. The clinical MRI report usually does not provide quantitative values that can be used to monitor developmental status. Recently, the importance of image quantification to detect and evaluate mild-to-moderate anatomical abnormalities has been emphasized because these alterations are possibly related to several psychiatric disorders and learning disabilities. In the research arena, structural MRI and diffusion tensor imaging (DTI) have been widely applied to quantify brain development of the pediatric population. To interpret the values from these MR modalities, a "growth percentile chart," which describes the mean and standard deviation of the normal developmental curve for each anatomical structure, is required. Although efforts have been made to create such a growth percentile chart based on MRI and DTI, one of the greatest challenges is to standardize the anatomical boundaries of the measured anatomical structures. To avoid inter- and intra-reader variability about the anatomical boundary definition, and hence, to increase the precision of quantitative measurements, an automated structure parcellation method, customized for the neonatal and pediatric population, has been developed. This method enables quantification of multiple MR modalities using a common analytic framework. In this paper, the attempt to create an MRI- and a DTI-based growth percentile chart, followed by an application to investigate developmental abnormalities related to cerebral palsy, Williams syndrome, and Rett syndrome, have been introduced. Future

  7. Low-Functioning Autism and Nonsyndromic Intellectual Disability: Magnetic Resonance Imaging (MRI) Findings.

    PubMed

    Erbetta, Alessandra; Bulgheroni, Sara; Contarino, Valeria Elisa; Chiapparini, Luisa; Esposito, Silvia; Annunziata, Silvia; Riva, Daria

    2015-10-01

    Previous neuroradiologic studies reported a high incidence of abnormalities in low-functioning autistic children. In this population, it is difficult to know which abnormality depends on autism itself and which is related to intellectual disability associated with autism. The aim of this study was to evaluate the frequency of neuroradiologic abnormalities in low-functioning autistic children compared to Intellectual Quotient and age-matched nonsyndromic children, using the same set of magnetic resonance imaging (MRI) sequences. MRI was rated as abnormal in 44% of autistic and 54% of children with intellectual disability. The main results were mega cisterna magna in autism and hypoplastic corpus callosum in intellectual disability. These abnormalities are morphologically visible signs of altered brain development. These findings, more frequent than expected, are not specific to the 2 conditions. Although MRI cannot be considered mandatory, it allows an in-depth clinical assessment in nonsyndromic intellectual-disabled and autistic children.

  8. Tissue Necrosis Monitoring for HIFU Ablation with T1 Contrast MRI Imaging

    NASA Astrophysics Data System (ADS)

    Hwang, San-Chao; Yao, Ching; Kuo, Ih-Yuan; Tsai, Wei-Cheng; Chang, Hsu

    2011-09-01

    In MR-guided HIFU ablation, MTC (Magnetization Transfer Contrast) or perfusion imaging is usually used after ablation to evaluate the ablated area based on the thermally induced necrosis contrast. In our MR-guided HIFU ablation study, a T1 contrast MRI scan sequence has been used to distinguish between necrotic and non-necrotic tissue. The ablation of porcine meat in-vitro and in-vivo pig leg muscle show that the necrotic area of T1 contrast MRI image coincides with the photographs of sliced specimen. The sequence is considerably easier to apply than MTC or perfusion imaging, while giving good necrosis contrast. In addition, no injection of contrast agent is needed, allowing multiple scans to be applied throughout the entire ablation procedure.

  9. Segmentation of MRI Brain Images with an Improved Harmony Searching Algorithm

    PubMed Central

    Yang, Zhang; Li, Guo; Weifeng, Ding

    2016-01-01

    The harmony searching (HS) algorithm is a kind of optimization search algorithm currently applied in many practical problems. The HS algorithm constantly revises variables in the harmony database and the probability of different values that can be used to complete iteration convergence to achieve the optimal effect. Accordingly, this study proposed a modified algorithm to improve the efficiency of the algorithm. First, a rough set algorithm was employed to improve the convergence and accuracy of the HS algorithm. Then, the optimal value was obtained using the improved HS algorithm. The optimal value of convergence was employed as the initial value of the fuzzy clustering algorithm for segmenting magnetic resonance imaging (MRI) brain images. Experimental results showed that the improved HS algorithm attained better convergence and more accurate results than those of the original HS algorithm. In our study, the MRI image segmentation effect of the improved algorithm was superior to that of the original fuzzy clustering method. PMID:27403428

  10. Segmentation of MRI Brain Images with an Improved Harmony Searching Algorithm.

    PubMed

    Yang, Zhang; Shufan, Ye; Li, Guo; Weifeng, Ding

    2016-01-01

    The harmony searching (HS) algorithm is a kind of optimization search algorithm currently applied in many practical problems. The HS algorithm constantly revises variables in the harmony database and the probability of different values that can be used to complete iteration convergence to achieve the optimal effect. Accordingly, this study proposed a modified algorithm to improve the efficiency of the algorithm. First, a rough set algorithm was employed to improve the convergence and accuracy of the HS algorithm. Then, the optimal value was obtained using the improved HS algorithm. The optimal value of convergence was employed as the initial value of the fuzzy clustering algorithm for segmenting magnetic resonance imaging (MRI) brain images. Experimental results showed that the improved HS algorithm attained better convergence and more accurate results than those of the original HS algorithm. In our study, the MRI image segmentation effect of the improved algorithm was superior to that of the original fuzzy clustering method.

  11. Normalization of T2W-MRI prostate images using Rician a priori

    NASA Astrophysics Data System (ADS)

    Lemaître, Guillaume; Rastgoo, Mojdeh; Massich, Joan; Vilanova, Joan C.; Walker, Paul M.; Freixenet, Jordi; Meyer-Baese, Anke; Mériaudeau, Fabrice; Martí, Robert

    2016-03-01

    Prostate cancer is reported to be the second most frequently diagnosed cancer of men in the world. In practise, diagnosis can be affected by multiple factors which reduces the chance to detect the potential lesions. In the last decades, new imaging techniques mainly based on MRI are developed in conjunction with Computer-Aided Diagnosis (CAD) systems to help radiologists for such diagnosis. CAD systems are usually designed as a sequential process consisting of four stages: pre-processing, segmentation, registration and classification. As a pre-processing, image normalization is a critical and important step of the chain in order to design a robust classifier and overcome the inter-patients intensity variations. However, little attention has been dedicated to the normalization of T2W-Magnetic Resonance Imaging (MRI) prostate images. In this paper, we propose two methods to normalize T2W-MRI prostate images: (i) based on a Rician a priori and (ii) based on a Square-Root Slope Function (SRSF) representation which does not make any assumption regarding the Probability Density Function (PDF) of the data. A comparison with the state-of-the-art methods is also provided. The normalization of the data is assessed by comparing the alignment of the patient PDFs in both qualitative and quantitative manners. In both evaluation, the normalization using Rician a priori outperforms the other state-of-the-art methods.

  12. Repeated BOLD-fMRI Imaging of Deep Brain Stimulation Responses in Rats

    PubMed Central

    Chao, Tzu-Hao Harry; Chen, Jyh-Horng; Yen, Chen-Tung

    2014-01-01

    Functional magnetic resonance imaging (fMRI) provides a picture of the global spatial activation pattern of the brain. Interest is growing regarding the application of fMRI to rodent models to investigate adult brain plasticity. To date, most rodent studies used an electrical forepaw stimulation model to acquire fMRI data, with α-chloralose as the anesthetic. However, α-chloralose is harmful to animals, and not suitable for longitudinal studies. Moreover, peripheral stimulation models enable only a limited number of brain regions to be studied. Processing between peripheral regions and the brain is multisynaptic, and renders interpretation difficult and uncertain. In the present study, we combined the medetomidine-based fMRI protocol (a noninvasive rodent fMRI protocol) with chronic implantation of an MRI-compatible stimulation electrode in the ventroposterior (VP) thalamus to repetitively sample thalamocortical responses in the rat brain. Using this model, we scanned the forebrain responses evoked by the VP stimulation repeatedly of individual rats over 1 week. Cortical BOLD responses were compared between the 2 profiles obtained at day1 and day8. We discovered reproducible frequency- and amplitude-dependent BOLD responses in the ipsilateral somatosensory cortex (S1). The S1 BOLD responses during the 2 sessions were conserved in maximal response amplitude, area size (size ratio from 0.88 to 0.91), and location (overlap ratio from 0.61 to 0.67). The present study provides a long-term chronic brain stimulation protocol for studying the plasticity of specific neural circuits in the rodent brain by BOLD-fMRI. PMID:24825464

  13. Visualizing arthritic inflammation and therapeutic response by fluorine-19 magnetic resonance imaging (19F MRI)

    PubMed Central

    2012-01-01

    Background Non-invasive imaging of inflammation to measure the progression of autoimmune diseases, such as rheumatoid arthritis (RA), and to monitor responses to therapy is critically needed. V-Sense, a perfluorocarbon (PFC) contrast agent that preferentially labels inflammatory cells, which are then recruited out of systemic circulation to sites of inflammation, enables detection by 19F MRI. With no 19F background in the host, detection is highly-specific and can act as a proxy biomarker of the degree of inflammation present. Methods Collagen-induced arthritis in rats, a model with many similarities to human RA, was used to study the ability of the PFC contrast agent to reveal the accumulation of inflammation over time using 19F MRI. Disease progression in the rat hind limbs was monitored by caliper measurements and 19F MRI on days 15, 22 and 29, including the height of clinically symptomatic disease. Naïve rats served as controls. The capacity of the PFC contrast agent and 19F MRI to assess the effectiveness of therapy was studied in a cohort of rats administered oral prednisolone on days 14 to 28. Results Quantification of 19F signal measured by MRI in affected limbs was linearly correlated with disease severity. In animals with progressive disease, increases in 19F signal reflected the ongoing recruitment of inflammatory cells to the site, while no increase in 19F signal was observed in animals receiving treatment which resulted in clinical resolution of disease. Conclusion These results indicate that 19F MRI may be used to quantitatively and qualitatively evaluate longitudinal responses to a therapeutic regimen, while additionally revealing the recruitment of monocytic cells involved in the inflammatory process to the anatomical site. This study may support the use of 19F MRI to clinically quantify and monitor the severity of inflammation, and to assess the effectiveness of treatments in RA and other diseases with an inflammatory component. PMID:22721447

  14. MRI-PET image fusion based on NSCT transform using local energy and local variance fusion rules.

    PubMed

    Amini, Nasrin; Fatemizadeh, E; Behnam, Hamid

    2014-05-01

    Image fusion means to integrate information from one image to another image. Medical images according to the nature of the images are divided into structural (such as CT and MRI) and functional (such as SPECT, PET). This article fused MRI and PET images and the purpose is adding structural information from MRI to functional information of PET images. The images decomposed with Nonsubsampled Contourlet Transform and then two images were fused with applying fusion rules. The coefficients of the low frequency band are combined by a maximal energy rule and coefficients of the high frequency bands are combined by a maximal variance rule. Finally, visual and quantitative criteria were used to evaluate the fusion result. In visual evaluation the opinion of two radiologists was used and in quantitative evaluation the proposed fusion method was compared with six existing methods and used criteria were entropy, mutual information, discrepancy and overall performance.

  15. Calibration standard of body tissue with magnetic nanocomposites for MRI and X-ray imaging

    NASA Astrophysics Data System (ADS)

    Rahn, Helene; Woodward, Robert; House, Michael; Engineer, Diana; Feindel, Kirk; Dutz, Silvio; Odenbach, Stefan; StPierre, Tim

    2016-05-01

    We present a first study of a long-term phantom for Magnetic Resonance Imaging (MRI) and X-ray imaging of biological tissues with magnetic nanocomposites (MNC) suitable for 3-dimensional and quantitative imaging of tissues after, e.g. magnetically assisted cancer treatments. We performed a cross-calibration of X-ray microcomputed tomography (XμCT) and MRI with a joint calibration standard for both imaging techniques. For this, we have designed a phantom for MRI and X-ray computed tomography which represents biological tissue enriched with MNC. The developed phantoms consist of an elastomer with different concentrations of multi-core MNC. The matrix material is a synthetic thermoplastic gel, PermaGel (PG). The developed phantoms have been analyzed with Nuclear Magnetic Resonance (NMR) Relaxometry (Bruker minispec mq 60) at 1.4 T to obtain R2 transverse relaxation rates, with SQUID (Superconducting QUantum Interference Device) magnetometry and Inductively Coupled Plasma Mass Spectrometry (ICP-MS) to verify the magnetite concentration, and with XμCT and 9.4 T MRI to visualize the phantoms 3-dimensionally and also to obtain T2 relaxation times. A specification of a sensitivity range is determined for standard imaging techniques X-ray computed tomography (XCT) and MRI as well as with NMR. These novel phantoms show a long-term stability over several months up to years. It was possible to suspend a particular MNC within the PG reaching a concentration range from 0 mg/ml to 6.914 mg/ml. The R2 relaxation rates from 1.4 T NMR-relaxometry show a clear connection (R2=0.994) with MNC concentrations between 0 mg/ml and 4.5 mg/ml. The MRI experiments have shown a linear correlation of R2 relaxation and MNC concentrations as well but in a range between MNC concentrations of 0 mg/ml and 1.435 mg/ml. It could be shown that XμCT displays best moderate and high MNC concentrations. The sensitivity range for this particular XμCT apparatus yields from 0.569 mg/ml to 6.914 mg/ml. The

  16. Image guidance based on MRI for spinal interstitial laser thermotherapy: technical aspects and accuracy.

    PubMed

    Tatsui, Claudio E; Nascimento, Clarissa N G; Suki, Dima; Amini, Behrang; Li, Jing; Ghia, Amol J; Thomas, Jonathan G; Stafford, R Jason; Rhines, Laurence D; Cata, Juan P; Kumar, Ashok J; Rao, Ganesh

    2017-02-10

    OBJECTIVE Image guidance for spinal procedures is based on 3D-fluoroscopy or CT, which provide poor visualization of soft tissues, including the spinal cord. To overcome this limitation, the authors developed a method to register intraoperative MRI (iMRI) of the spine into a neuronavigation system, allowing excellent visualization of the spinal cord. This novel technique improved the accuracy in the deployment of laser interstitial thermal therapy probes for the treatment of metastatic spinal cord compression. METHODS Patients were positioned prone on the MRI table under general anesthesia. Fiducial markers were applied on the skin of the back, and a plastic cradle was used to support the MRI coil. T2-weighted MRI sequences of the region of interest were exported to a standard navigation system. A reference array was sutured to the skin, and surface matching of the fiducial markers was performed. A navigated Jamshidi needle was advanced until contact was made with the dorsal elements; its position was confirmed with intraoperative fluoroscopy prior to advancement into a target in the epidural space. A screenshot of its final position was saved, and then the Jamshidi needle was exchanged for an MRI-compatible access cannula. MRI of the exact axial plane of each access cannula was obtained and compared with the corresponding screenshot saved during positioning. The discrepancy in millimeters between the trajectories was measured to evaluate accuracy of the image guidance RESULTS Thirteen individuals underwent implantation of 47 laser probes. The median absolute value of the discrepancy between the location predicted by the navigation system and the actual position of the access cannulas was 0.7 mm (range 0-3.2 mm). No injury or adverse event occurred during the procedures. CONCLUSIONS This study demonstrates the feasibility of image guidance based on MRI to perform laser interstitial thermotherapy of spinal metastasis. The authors' method permits excellent

  17. Simultaneous imaging of locus coeruleus and substantia nigra with a quantitative neuromelanin MRI approach.

    PubMed

    Chen, Xiangchuan; Huddleston, Daniel E; Langley, Jason; Ahn, Sinyeob; Barnum, Christopher J; Factor, Stewart A; Levey, Allan I; Hu, Xiaoping

    2014-12-01

    Quantitative MRI of neuromelanin (NM) containing structures (referred to as NM-MRI) in the brainstem, namely the locus coeruleus (LC) and substantia nigra (SN), may assist with the early detection of Parkinson's disease (PD) and Alzheimer's disease (AD) as well as differential diagnosis in the early disease stages. In this study, two gradient echo (GRE) sequences with magnetization transfer contrast (MTC) preparation pulses were developed to simultaneously image the LC and SN. This has been a challenge with NM-MRI techniques used in previous studies due to the relatively high specific absorption rate (SAR) induced by these techniques. In addition, a semi-automated quantitative analysis scheme was applied to estimate volumes and contrast-to-noise ratios (CNR) of the LC and SN based on segmentation of both structures. Compared to a T1-weighted turbo spin echo (TSE) sequence typically used for simultaneous imaging of the LC and SN, the two GRE-MTC sequences exhibited improved performance in terms of higher sensitivity (in CNR) in imaging the SN and lower SAR during the scans. A multiple-measurement protocol was adopted as well so that motion degraded measurements could be removed and artifacts associated with motion could be corrected. The present approach has demonstrated advantages in image acquisition (lower SAR and higher sensitivity), image pre-processing (with motion correction) and quantitative image analysis (segmentation-based estimation of volume and CNR) when compared with existing NM-MRI approaches. This approach has potential for detection and monitoring of neurodegeneration in LC and SN in disease states including AD and PD.

  18. MRI Reporter Genes: Application to Imaging of Cell Survival, Proliferation, Migration, and Differentiation

    PubMed Central

    Vandsburger, Moriel H; Radoul, Marina; Cohen, Batya; Neeman, Michal

    2013-01-01

    Molecular imaging strives to detect molecular events at the level of the whole organism. In some cases, the molecule of interest can be detected either directly, or through the use of targeted contrast media. However many genes and proteins, and particularly those located in intracellular compartments, are not accessible for targeted agents. The transcriptional regulation of these genes can never the less be detected, though indirectly, through the use of reporter genes encoding for readily detectable proteins. Such reporter proteins can be expressed in the tissue of interest by genetically introducing the reporter gene in the target cells. Imaging of reporter genes has become a powerful tool in modern biomedical research. Typically, expression of fluorescent or bioluminescent proteins, or the reaction product of expressed enzymes and exogenous substrates, are examined using in vitro histological methods, or in vivo whole body imaging methods. Recent advances in MRI reporter gene methods raise the possibility that MRI could become a powerful tool for concomitant high resolution anatomical and functional imaging and for imaging of reporter gene activity. An immediate application of MRI reporter gene methods is for monitoring gene expression patterns in gene therapy and for in vivo imaging of the survival, proliferation, migration, and differentiation of pluripotent or multipotent cells used in cell based regenerative therapies for cancer, myocardial infarction, and neural degeneration. In this review, we characterize the variety of MRI reporter gene methods based on their applicability to report cell survival/proliferation, cell migration, and cell differentiation. In particular, we discuss which methods are best suited for translation to clinical use in regenerative therapies. PMID:23225197

  19. Measuring Pain for Patients Seeking Physical Therapy: Can Functional Magnetic Resonance Imaging (fMRI) Help?

    PubMed

    Elliott, James M; Owen, Meriel; Bishop, Mark D; Sparks, Cheryl; Tsao, Henry; Walton, David M; Weber, Kenneth A; Wideman, Timothy H

    2016-07-28

    In the multidisciplinary fields of pain medicine and rehabilitation, advancing techniques such as functional magnetic resonance imaging (fMRI) are used to enhance our understanding of the pain experience. Given that such measures, in some circles, are expected to help us understand the brain in pain, future research in pain measurement is undeniably rich with possibility. However, pain remains intensely personal and represents a multifaceted experience, unique to each individual; no single measure in isolation, fMRI included, can prove or quantify its magnitude beyond the patient self-report. Physical therapists should be aware of cutting-edge advances in measuring the patient's pain experience, and they should work closely with professionals in other disciplines (eg, magnetic resonance physicists, biomedical engineers, radiologists, psychologists) to guide the exploration and development of multimodal pain measurement and management on a patient-by-patient basis. The primary purpose of this perspective article is to provide a brief overview of fMRI and inform physical therapist clinicians of the pros and cons when utilized as a measure of the patient's perception of pain. A secondary purpose is to describe current known factors that influence the quality of fMRI data and its analyses, as well as the potential for future clinical applications relevant to physical therapist practice. Lastly, the interested reader is introduced and referred to existing guidelines and recommendations for reporting fMRI research.

  20. Robust Fluoroscopic Tracking of Fiducial Markers: Exploiting the Spatial Constraints

    PubMed Central

    Li, Rui; Sharp, Gregory

    2013-01-01

    Two new fluoroscopic fiducial tracking methods that exploit the spatial relationship among the multiple implanted fiducial to achieve fast, accurate and robust tracking are proposed in this paper. The spatial relationship between multiple implanted markers are modeled as Gaussian distributions of their pairwise distances over time. The means and standard deviations of these distances are learned from training sequences, and pairwise distances that deviate from these learned distributions are assigned a low spatial matching score. The spatial constraints are incorporated in two different algorithms: a stochastic tracking method and a detection based method. In the stochastic method, hypotheses of the “true” fiducial position are sampled from a pre-trained respiration motion model. Each hypothesis is assigned an importance value based on image matching score and spatial matching score. Learning the parameters of the motion model is needed in addition to the learning the distribution parameters of the pairwise distances in the proposed stochastic tracking approach. In the detection based method, a set of possible marker locations are identified by using a template matching based fiducial detector. The best location is obtained by optimizing the image matching score and spatial matching score through non-serial dynamic programming. In this detection based approach, there is no need to learn the respiration motion model. The two proposed algorithms are compared with a recent work using multiple hypothesis tracking algorithm which is denoted by MHT[19]. Phantom experiments were performed using fluoroscopic videos captured with known motion relative to an anthropomorphic phantom. The patient experiments were performed using a retrospective study of 16 fluoroscopic videos of liver cancer patients with implanted fiducials. For the motion phantom data sets, the detection based approach has the smallest tracking error (μerr: 0.78 – 1.74 mm, σerr: 0.39 – 1.16 mm) for

  1. Automated localization of vertebra landmarks in MRI images

    NASA Astrophysics Data System (ADS)

    Pai, Akshay; Narasimhamurthy, Anand; Rao, V. S. Veeravasarapu; Vaidya, Vivek

    2011-03-01

    The identification of key landmark points in an MR spine image is an important step for tasks such as vertebra counting. In this paper, we propose a template matching based approach for automatic detection of two key landmark points, namely the second cervical vertebra (C2) and the sacrum from sagittal MR images. The approach is comprised of an approximate localization of vertebral column followed by matching with appropriate templates in order to detect/localize the landmarks. A straightforward extension of the work described here is an automated classification of spine section(s). It also serves as a useful building block for further automatic processing such as extraction of regions of interest for subsequent image processing and also in aiding the counting of vertebra.

  2. Skin age testing criteria: characterization of human skin structures by 500 MHz MRI multiple contrast and image processing.

    PubMed

    Sharma, Rakesh

    2010-07-21

    Ex vivo magnetic resonance microimaging (MRM) image characteristics are reported in human skin samples in different age groups. Human excised skin samples were imaged using a custom coil placed inside a 500 MHz NMR imager for high-resolution microimaging. Skin MRI images were processed for characterization of different skin structures. Contiguous cross-sectional T1-weighted 3D spin echo MRI, T2-weighted 3D spin echo MRI and proton density images were compared with skin histopathology and NMR peaks. In all skin specimens, epidermis and dermis thickening and hair follicle size were measured using MRM. Optimized parameters TE and TR and multicontrast enhancement generated better MRI visibility of different skin components. Within high MR signal regions near to the custom coil, MRI images with short echo time were comparable with digitized histological sections for skin structures of the epidermis, dermis and hair follicles in 6 (67%) of the nine specimens. Skin % tissue composition, measurement of the epidermis, dermis, sebaceous gland and hair follicle size, and skin NMR peaks were signatures of skin type. The image processing determined the dimensionality of skin tissue components and skin typing. The ex vivo MRI images and histopathology of the skin may be used to measure the skin structure and skin NMR peaks with image processing may be a tool for determining skin typing and skin composition.

  3. Skin age testing criteria: characterization of human skin structures by 500 MHz MRI multiple contrast and image processing

    NASA Astrophysics Data System (ADS)

    Sharma, Rakesh

    2010-07-01

    Ex vivo magnetic resonance microimaging (MRM) image characteristics are reported in human skin samples in different age groups. Human excised skin samples were imaged using a custom coil placed inside a 500 MHz NMR imager for high-resolution microimaging. Skin MRI images were processed for characterization of different skin structures. Contiguous cross-sectional T1-weighted 3D spin echo MRI, T2-weighted 3D spin echo MRI and proton density images were compared with skin histopathology and NMR peaks. In all skin specimens, epidermis and dermis thickening and hair follicle size were measured using MRM. Optimized parameters TE and TR and multicontrast enhancement generated better MRI visibility of different skin components. Within high MR signal regions near to the custom coil, MRI images with short echo time were comparable with digitized histological sections for skin structures of the epidermis, dermis and hair follicles in 6 (67%) of the nine specimens. Skin % tissue composition, measurement of the epidermis, dermis, sebaceous gland and hair follicle size, and skin NMR peaks were signatures of skin type. The image processing determined the dimensionality of skin tissue components and skin typing. The ex vivo MRI images and histopathology of the skin may be used to measure the skin structure and skin NMR peaks with image processing may be a tool for determining skin typing and skin composition.

  4. Prioritization of brain MRI volumes using medical image perception model and tumor region segmentation.

    PubMed

    Mehmood, Irfan; Ejaz, Naveed; Sajjad, Muhammad; Baik, Sung Wook

    2013-10-01

    The objective of the present study is to explore prioritization methods in diagnostic imaging modalities to automatically determine the contents of medical images. In this paper, we propose an efficient prioritization of brain MRI. First, the visual perception of the radiologists is adapted to identify salient regions. Then this saliency information is used as an automatic label for accurate segmentation of brain lesion to determine the scientific value of that image. The qualitative and quantitative results prove that the rankings generated by the proposed method are closer to the rankings created by radiologists.

  5. Ultra-Fast MRI of the Human Brain with Simultaneous Multi-Slice Imaging

    PubMed Central

    Feinberg, David A.; Setsompop, Kawin

    2013-01-01

    The recent advancement of simultaneous multi-slice imaging using multiband excitation has dramatically reduced the scan time of the brain. The evolution of this parallel imaging technique began over a decade ago and through recent sequence improvements has reduced the acquisition time of multi-slice EPI by over ten fold. This technique has recently become extremely useful for i) functional MRI studies for improving the statistical definition of neuronal networks, and ii) diffusion based fiber tractography for improving the ability to visualize structural connections in the human brain. Several applications and evaluations are underway which show promise for this family of fast imaging sequences. PMID:23473893

  6. Microcomputer-based image processing system for CT/MRI scans: II. Expert system

    NASA Astrophysics Data System (ADS)

    Kwok, John C. K.; Yu, Peter K. N.; Cheng, Andrew Y. S.; Ho, Wai-Chin

    1991-06-01

    A microcomputer-based image processing system is used to digitize and process serial sections of CT/MRI scan and reconstruct three-dimensional images of brain structures and brain lesions. The images grabbed also serve as templates and different vital regions with different risk values are also traced out for 3D reconstruction. A knowledge-based system employing rule-based programming has been built to help identifying brain lesions and to help planning trajectory for operations. The volumes of the lesions are also automatically determined. Such system is very useful for medical skills archival, tumor size monitoring, survival and outcome forecasting, and consistent neurosurgical planning.

  7. Segmentation and length measurement of the abdominal blood vessels in 3-D MRI images.

    PubMed

    Babin, Danilo; Vansteenkiste, Ewout; Pizurica, Aleksandra; Philips, Wilfried

    2009-01-01

    In diagnosing diseases and planning surgeries the structure and length of blood vessels is of great importance. In this research we develop a novel method for the segmentation of 2-D and 3-D images with an application to blood vessel length measurements in 3-D abdominal MRI images. Our approach is robust to noise and does not require contrast-enhanced images for segmentation. We use an effective algorithm for skeletonization, graph construction and shortest path estimation to measure the length of blood vessels of interest.

  8. Magnetic Resonance Imaging (MRI) Markers for MRI-Guided High-Dose-Rate Brachytherapy: Novel Marker-Flange for Cervical Cancer and Marker Catheters for Prostate Cancer

    SciTech Connect

    Schindel, Joshua; Muruganandham, Manickam; Pigge, F. Christopher; Anderson, James; Kim, Yusung

    2013-06-01

    Purpose: To present a novel marker-flange, addressing source-reconstruction uncertainties due to the artifacts of a titanium intracavitary applicator used for magnetic resonance imaging (MRI)-guided high-dose-rate (HDR) brachytherapy (BT); and to evaluate 7 different MRI marker agents used for interstitial prostate BT and intracavitary gynecologic HDR BT when treatment plans are guided by MRI. Methods and Materials: Seven MRI marker agents were analyzed: saline solution, Conray-60, copper sulfate (CuSO{sub 4}) (1.5 g/L), liquid vitamin E, fish oil, 1% agarose gel (1 g agarose powder per 100 mL distilled water), and a cobalt–chloride complex contrast (C4) (CoCl{sub 2}/glycine = 4:1). A plastic, ring-shaped marker-flange was designed and tested on both titanium and plastic applicators. Three separate phantoms were designed to test the marker-flange, interstitial catheters for prostate BT, and intracavitary catheters for gynecologic HDR BT. T1- and T2-weighted MRI were analyzed for all markers in each phantom and quantified as percentages compared with a 3% agarose gel background. The geometric accuracy of the MR signal for the marker-flange was measured using an MRI-CT fusion. Results: The CuSO{sub 4} and C4 markers on T1-weighted MRI and saline on T2-weighted MRI showed the highest signals. The marker-flange showed hyper-signals of >500% with CuSO{sub 4} and C4 on T1-weighted MRI and of >400% with saline on T2-weighted MRI on titanium applicators. On T1-weighted MRI, the MRI signal inaccuracies of marker-flanges were measured <2 mm, regardless of marker agents, and that of CuSO{sub 4} was 0.42 ± 0.14 mm. Conclusion: The use of interstitial/intracavitary markers for MRI-guided prostate/gynecologic BT was observed to be feasible, providing accurate source pathway reconstruction. The novel marker-flange can produce extremely intense, accurate signals, demonstrating its feasibility for gynecologic HDR BT.

  9. Gray matter myelination of 1555 human brains using partial volume corrected MRI images

    PubMed Central

    Shafee, Rebecca; Buckner, Randy L.; Fischl, Bruce

    2014-01-01

    The myelin content of the cortex changes over the human lifetime and aberrant cortical myelination is associated with diseases such as schizophrenia and multiple sclerosis. Recently magnetic resonance imaging (MRI) techniques have shown potential in differentiating between myeloarchitectonically distinct cortical regions in vivo. Here we introduce a new algorithm for correcting partial volume effects present in mm-scale MRI images which was used to investigate the myelination pattern of the cerebral cortex in 1555 clinically normal subjects using the ratio of T1-weighted (T1w) and T2-weighted (T2w) MRI images. A significant linear cross-sectional age increase in T1w/T2w estimated myelin was detected across an 18 to 35 year age span (highest value of ~ 1%/year compared to mean T1w/T2w myelin value at 18 years). The cortex was divided at mid-thickness and the value of T1w/T2w myelin calculated for the inner and the outer layers separately. The increase in T1w/T2w estimated myelin occurs predominantly in the inner layer for most cortical regions. The ratio of the inner and outer layer T1w/T12w myelin was further validated using high-resolution in vivo MRI scans and also a high-resolution MRI scan of a postmortem brain. Additionally, the relationships between cortical thickness, curvature and T1w/T2w estimated myelin were found to be significant, although the relationships varied across the cortex. We discuss these observations as well as limitations of using the T1w/T2w ratio as an estimate of cortical myelin. PMID:25449739

  10. Review of MRI technique and imaging findings in athletic pubalgia and the "sports hernia".

    PubMed

    Mullens, Frank E; Zoga, Adam C; Morrison, William B; Meyers, William C

    2012-12-01

    The clinical syndrome of athletic pubalgia has prematurely ended many promising athletic careers, has made many active, fitness conscious adults more sedentary, and has served as a diagnostic and therapeutic conundrum for innumerable trainers and physicians worldwide for decades. This diagnosis actually arises from one or more lesions within a spectrum of musculoskeletal and visceral injuries. In recent years, MRI has helped define many of these syndromes, and has proven to be both sensitive and specific for numerous potential causes of athletic pubalgia. This text will provide a comprehensive, up to date review of expected and sometimes unexpected MRI findings in the setting of athletic pubalgia, and will delineate an imaging algorithm and MRI protocol to help guide radiologists and other clinicians dealing with refractory, activity related groin pain in an otherwise young, healthy patient. There is still more to be learned about prevention and treatment plans for athletic pubalgia lesions, but accurate diagnosis should be much less nebulous and difficult with the use of MRI as a primary imaging modality.

  11. Single-Step Assembly of Multi-Modal Imaging Nanocarriers: MRI and Long-Wavelength Fluorescence Imaging

    PubMed Central

    Pinkerton, Nathalie M.; Gindy, Marian E.; Calero-DdelC, Victoria L.; Wolfson, Theodore; Pagels, Robert F.; Adler, Derek; Gao, Dayuan; Li, Shike; Wang, Ruobing; Zevon, Margot; Yao, Nan; Pacheco, Carlos; Therien, Michael J.; Rinaldi, Carlos; Sinko, Patrick J.

    2015-01-01

    MRI and NIR-active, multi-modal Composite NanoCarriers (CNCs) are prepared using a simple, one-step process, Flash NanoPrecipitation (FNP). The FNP process allows for the independent control of the hydrodynamic diameter, co-core excipient and NIR dye loading, and iron oxide-based nanocrystal (IONC) content of the CNCs. In the controlled precipitation process, 10 nm IONCs are encapsulated into poly(ethylene glycol) stabilized CNCs to make biocompatible T2 contrast agents. By adjusting the formulation, CNC size is tuned between 80 and 360 nm. Holding the CNC size constant at an intensity weighted average diameter of 99 ± 3 nm (PDI width 28 nm), the particle relaxivity varies linearly with encapsulated IONC content ranging from 66 to 533 mM-1s-1 for CNCs formulated with 4 to 16 wt% IONC. To demonstrate the use of CNCs as in vivo MRI contrast agents, CNCs are surface functionalized with liver targeting hydroxyl groups. The CNCs enable the detection of 0.8 mm3 non-small cell lung cancer metastases in mice livers via MRI. Incorporating the hydrophobic, NIR dye PZn3 into CNCs enables complementary visualization with long-wavelength fluorescence at 800 nm. In vivo imaging demonstrates the ability of CNCs to act both as MRI and fluorescent imaging agents. PMID:25925128

  12. Clinical cell therapy imaging using a perfluorocarbon tracer and fluorine-19 MRI

    PubMed Central

    Ahrens, Eric T; Helfer, Brooke M; O'Hanlon, Charles F; Schirda, Claudiu

    2014-01-01

    Purpose Cellular therapeutics are emerging as a treatment option for a host of serious human diseases. To accelerate clinical translation, noninvasive imaging of cell grafts in clinical trials can potentially be used to assess the initial delivery and behavior of cells. Methods The use of a perfluorocarbon (PFC) tracer agent for clinical fluorine-19 (19F) MRI cell detection is described. This technology was used to detect immunotherapeutic dendritic cells (DCs) delivered to colorectal adenocarcinoma patients. Autologous DC vaccines were labeled with a PFC MRI agent ex vivo. Patients received DCs intradermally, and 19F spin-density-weighted MRI at 3 Tesla (T) was used to observe cells. Results Spin-density-weighted 19F images at the injection site displayed DCs as background-free “hot-spot” images. 19F images were acquired in clinically relevant scan times (<10 min). Apparent DC numbers could be quantified in two patients from the 19F hot-spots and were observed to decrease by ∼50% at injection site by 24 h. From 3T phantom studies, the sensitivity limit for DC detection is estimated to be on the order of ∼105 cells/voxel in this study. Conclusion These results help to establish a clinically applicable means to track a broad range of cell types used in cell therapy. Magn Reson Med 72:1696–1701, 2014. © 2014 The Authors. Magnetic Resonance in Medicine Published by Wiley Periodicals, Inc. on behalf of International Society of Medicine in Resonance. PMID:25241945

  13. Evaluation of congenital heart disease by cine magnetic resonance imaging (MRI)

    SciTech Connect

    Feiglin, D.H.I.; Moodie, D.S.; O'Donnell, J.K.; Go, R.T.; Sterba, R.; MacIntyre, W.J.

    1985-05-01

    The authors studied 11 adult patients (pts) with atrial septal defect (ASD) and 4 adult pts with ventricular septal defect (VSD) using cine magnetic resonance. All studies were performed using a .6T superconducting magnet with ECG gating and electronic axial rotation when appropriate. Repeated multislice image with no change in physiologic delay of the spin echo pulse sequence, but varying the time by offsetting one slice at each imaging stage allowed for an N x N collection of data where N is the number of slices in one collection set and is equal to the number of sets collected. Algebraic manipulation of the T1 weighted images (TE=30mSec TRimaging of the atrial septum than does conventional MRI. Using this technique, the authors have identified both atrial and ventricular septal defects in all pts preoperatively and have noted an intact atrial septum following surgery. Standard MRI produced 4 false positive studies postoperatively because only 1 phase of the cardiac cycle was reviewed. Cine MRI allows better identification of septal defects than standard static acquisitions. The cine technique also provides better definition and delineation of right sided abnormalities which are maximized when viewed in a cardiac major axis obtained by electronic axial rotation.

  14. 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

  15. 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.

  16. Multimodality Functional Imaging in Radiation Therapy Planning: Relationships between Dynamic Contrast-Enhanced MRI, Diffusion-Weighted MRI, and 18F-FDG PET

    PubMed Central

    Mera Iglesias, Moisés; Aramburu Núñez, David; del Olmo Claudio, José Luis; Salvador Gómez, Francisco; Driscoll, Brandon; Coolens, Catherine; Alba Castro, José L.; Muñoz, Victor

    2015-01-01

    Objectives. Biologically guided radiotherapy needs an understanding of how different functional imaging techniques interact and link together. We analyse three functional imaging techniques that can be useful tools for achieving this objective. Materials and Methods. The three different imaging modalities from one selected patient are ADC maps, DCE-MRI, and 18F-FDG PET/CT, because they are widely used and give a great amount of complementary information. We show the relationship between these three datasets and evaluate them as markers for tumour response or hypoxia marker. Thus, vascularization measured using DCE-MRI parameters can determine tumour hypoxia, and ADC maps can be used for evaluating tumour response. Results. ADC and DCE-MRI include information from 18F-FDG, as glucose metabolism is associated with hypoxia and tumour cell density, although 18F-FDG includes more information about the malignancy of the tumour. The main disadvantage of ADC maps is the distortion, and we used only low distorted regions, and extracellular volume calculated from DCE-MRI can be considered equivalent to ADC in well-vascularized areas. Conclusion. A dataset for achieving the biologically guided radiotherapy must include a tumour density study and a hypoxia marker. This information can be achieved using only MRI data or only PET/CT studies or mixing both datasets. PMID:25788972

  17. Automatic localization of the left ventricle in cardiac MRI images using deep learning.

    PubMed

    Emad, Omar; Yassine, Inas A; Fahmy, Ahmed S

    2015-08-01

    Automatic localization of the left ventricle (LV) in cardiac MRI images is an essential step for automatic segmentation, functional analysis, and content based retrieval of cardiac images. In this paper, we introduce a new approach based on deep Convolutional Neural Network (CNN) to localize the LV in cardiac MRI in short axis views. A six-layer CNN with different kernel sizes was employed for feature extraction, followed by Softmax fully connected layer for classification. The pyramids of scales analysis was introduced in order to take account of the different sizes of the heart. A publically-available database of 33 patients was used for learning and testing. The proposed method was able it localize the LV with 98.66%, 83.91% and 99.07% for accuracy, sensitivity and specificity respectively.

  18. SU-E-J-257: Image Artifacts Caused by Implanted Calypso Beacons in MRI Studies

    SciTech Connect

    Amro, H; Chetty, I; Gordon, J; Wen, N

    2014-06-01

    Purpose: The presence of Calypso Beacon-transponders in patients can cause artifacts during MRI imaging studies. This could be a problem for post-treatment follow up of cancer patients using MRI studies to evaluate metastasis and for functional imaging studies.This work assesses (1) the volume immediately surrounding the transponders that will not be visualized by the MRI due to the beacons, and (2) the dependence of the non-visualized volume on beacon orientation, and scanning techniques. Methods: Two phantoms were used in this study (1) water filled box, (2) and a 2300 cc block of pork meat. Calypso beacons were implanted in the phantoms both in parallel and perpendicular orientations with respect to the MR scanner magnetic field. MR image series of the phantom were obtained with on a 1.0T high field open MR-SIM with multiple pulse sequences, for example, T1-weighted fast field echo and T2-weighted turbo spin echo. Results: On average, a no-signal region with 2 cm radius and 3 cm length was measured. Image artifacts are more significant when beacons are placed parallel to scanner magnetic field; the no-signal area around the beacon was about 0.5 cm larger in orthogonal orientation. The no-signal region surrounding the beacons slightly varies in dimension for the different pulse sequences. Conclusion: The use of Calypso beacons can prohibit the use of MRI studies in post-treatment assessments, especially in the immediate region surrounding the implanted beacon. A characterization of the MR scanner by identifying the no-signal regions due to implanted beacons is essential. This may render the use of Calypso beacons useful for some cases and give the treating physician a chance to identify those patients prior to beacon implantation.

  19. Local experience in cervical cancer imaging: Comparison in tumour assessment between TRUS and MRI

    PubMed Central

    Ordeanu, Claudia; Pop, Diana Cristina; Badea, Radu; Csutak, Csaba; Todor, Nicolae; Ordeanu, Calin; Kerekes, Reka; Coza, Ovidiu; Nagy, Viorica; Achimas-Cadariu, Patriciu; Irimie, Alexandru

    2015-01-01

    Objective The aim of study was to analyze the accuracy of TRUS (transrectal ultrasound) vs. MRI (magnetic resonance imaging) and clinical gynecological examination estimation in the evaluation of tumor dimensions. Methods The patients inclusion criterion included primarily pathologically squamous cell carcinoma, but excluded were patients who had not undergone BT (brachytherapy) and treated with palliative intent. We offer two types of treatment for locally advanced cervical cancer: (a) radiochemotherapy followed by surgery and (b) exclusive radiochemotherapy. Imaging tests follow the presence of tumor and tumor size (width and thickness). Each examination was performed by a different physician who had no knowledge of the others’ findings. All patients underwent MRI prior to EBRT (external beam radiation therapy) while 18 of them also at the time of the first brachytherapy application. For the analysis we used the r-Pearson correlation coefficient. Results In 2013, 26 patients with cervical cancer were included. A total of 44 gynecological examinations were performed, 44 MRIs and 18 TRUSs. For the comparisons prior to EBRT the correlation coefficient between TRUS vs. MRI was r = 0.79 for AP and r = 0.83 for LL, for GYN vs. MRI was r = 0.6 for AP and r = 0.75 for LL. Prior to BT for GYN vs. MRI, r values were 0.60 and 0.63 for AP and LL, respectively; for GYN vs. TRUS, r values were 0.56 and 0.78 for AP and LL, respectively. Conclusions A high correlation between the three examinations was obtained. As such, TRUS can be considered a suitable method in the evaluation of tumor dimensions. PMID:25949227

  20. MRI-based biomechanical imaging: initial study on early plaque progression and vessel remodeling

    PubMed Central

    Zheng, Jie; Abendschein, Dana R.; Okamoto, Ruth J.; Yang, Deshan; McCommis, Kyle S.; Misselwitz, Bernd; Gropler, Robert J.; Tang, Dalin

    2010-01-01

    The goal of the study is to develop a noninvasive magnetic resonance imaging (MRI)-based biomechanical imaging technique to address biomechanical pathways of atherosclerotic progression and regression in vivo using a 3D fluid-structure interaction (FSI) model. Initial in vivo study was carried out in an early plaque model in pigs that underwent balloon-overstretch injury to the left carotid arteries. Consecutive MRI scans were performed while the pigs were maintained on high cholesterol (progression) or normal chow (regression), with an injection of a plaque-targeted contrast agent, Gadofluorine M. At the end of study, the specimens of carotid arterial segments were dissected and underwent dedicated mechanical testing to determine their material properties. 3D FSI computational model was applied to calculate structure stress and strain distribution. The plaque structure resembles early plaque with thickened intima. Lower maximal flow shear stress correlates with the growth of plaque volume during progression, but not during regression. In contrast, maximal principle structure stress/stain (stress-P1 and strain-P1) were shown to correlate strongly with the change in the plaque dimension during regression, but moderately during progression. This MRI-based biomechanical imaging method may allow for noninvasive dynamic assessment of local hemodynamic forces on the development of atherosclerotic plaques in vivo. PMID:19559552

  1. Development of Laser-Polarized Noble Gas Magnetic Resonance Imaging (MRI) Technology

    NASA Technical Reports Server (NTRS)

    Walsworth, Ronald L.

    2004-01-01

    We are developing technology for laser-polarized noble gas nuclear magnetic resonance (NMR), with the aim of enabling it as a novel biomedical imaging tool for ground-based and eventually space-based application. This emerging multidisciplinary technology enables high-resolution gas-space magnetic resonance imaging (MRI)-e.g., of lung ventilation, perfusion, and gas-exchange. In addition, laser-polarized noble gases (3He and 1BXe) do not require a large magnetic field for sensitive NMR detection, opening the door to practical MRI with novel, open-access magnet designs at very low magnetic fields (and hence in confined spaces). We are pursuing two specific aims in this technology development program. The first aim is to develop an open-access, low-field (less than 0.01 T) instrument for MRI studies of human gas inhalation as a function of subject orientation, and the second aim is to develop functional imaging of the lung using laser-polarized He-3 and Xe-129.

  2. Non-cryogenic anatomical imaging in ultra-low field regime: hand MRI demonstration.

    PubMed

    Savukov, I; Karaulanov, T; Castro, A; Volegov, P; Matlashov, A; Urbatis, A; Gomez, J; Espy, M

    2011-08-01

    Ultra-low field (ULF) MRI with a pulsed prepolarization is a promising method with potential for applications where conventional high-, mid-, and low-field medical MRI cannot be used due to cost, weight, or other restrictions. Previously, successful ULF demonstrations of anatomical imaging were made using liquid helium-cooled SQUIDs and conducted inside a magnetically shielded room. The Larmor frequency for these demonstrations was ∼3 kHz. In order to make ULF MRI more accessible, portable, and inexpensive, we have recently developed a non-cryogenic system. To eliminate the requirement for a magnetically shielded room and improve the detection sensitivity, we increased the frequency to 83.6 kHz. While the background noise at these frequencies is greatly reduced, this is still within the ULF regime and most of its advantages such as simplicity in magnetic field generation hardware, and less stringent requirements for uniform fields, remaining. In this paper we demonstrate use of this system to image a human hand with up to 1.5mm resolution. The signal-to-noise ratio was sufficient to reveal anatomical features within a scan time of less than 7 min. This prototype can be scaled up for constructing head and full body scanners, and work is in progress toward demonstration of head imaging.

  3. Atlas-guided generation of pseudo-CT images for MRI-only and hybrid PET-MRI-guided radiotherapy treatment planning.

    PubMed

    Arabi, Hossein; Koutsouvelis, Nikolaos; Rouzaud, Michel; Miralbell, Raymond; Zaidi, Habib

    2016-09-07

    Magnetic resonance imaging (MRI)-guided attenuation correction (AC) of positron emission tomography (PET) data and/or radiation therapy (RT) treatment planning is challenged by the lack of a direct link between MRI voxel intensities and electron density. Therefore, even if this is not a trivial task, a pseudo-computed tomography (CT) image must be predicted from MRI alone. In this work, we propose a two-step (segmentation and fusion) atlas-based algorithm focusing on bone tissue identification to create a pseudo-CT image from conventional MRI sequences and evaluate its performance against the conventional MRI segmentation technique and a recently proposed multi-atlas approach. The clinical studies consisted of pelvic CT, PET and MRI scans of 12 patients with loco-regionally advanced rectal disease. In the first step, bone segmentation of the target image is optimized through local weighted atlas voting. The obtained bone map is then used to assess the quality of deformed atlases to perform voxel-wise weighted atlas fusion. To evaluate the performance of the method, a leave-one-out cross-validation (LOOCV) scheme was devised to find optimal parameters for the model. Geometric evaluation of the produced pseudo-CT images and quantitative analysis of the accuracy of PET AC were performed. Moreover, a dosimetric evaluation of volumetric modulated arc therapy photon treatment plans calculated using the different pseudo-CT images was carried out and compared to those produced using CT images serving as references. The pseudo-CT images produced using the proposed method exhibit bone identification accuracy of 0.89 based on the Dice similarity metric compared to 0.75 achieved by the other atlas-based method. The superior bone extraction resulted in a mean standard uptake value bias of  -1.5  ±  5.0% (mean  ±  SD) in bony structures compared to  -19.9  ±  11.8% and  -8.1  ±  8.2% achieved by MRI segmentation-based (water

  4. Atlas-guided generation of pseudo-CT images for MRI-only and hybrid PET-MRI-guided radiotherapy treatment planning

    NASA Astrophysics Data System (ADS)

    Arabi, Hossein; Koutsouvelis, Nikolaos; Rouzaud, Michel; Miralbell, Raymond; Zaidi, Habib

    2016-09-01

    Magnetic resonance imaging (MRI)-guided attenuation correction (AC) of positron emission tomography (PET) data and/or radiation therapy (RT) treatment planning is challenged by the lack of a direct link between MRI voxel intensities and electron density. Therefore, even if this is not a trivial task, a pseudo-computed tomography (CT) image must be predicted from MRI alone. In this work, we propose a two-step (segmentation and fusion) atlas-based algorithm focusing on bone tissue identification to create a pseudo-CT image from conventional MRI sequences and evaluate its performance against the conventional MRI segmentation technique and a recently proposed multi-atlas approach. The clinical studies consisted of pelvic CT, PET and MRI scans of 12 patients with loco-regionally advanced rectal disease. In the first step, bone segmentation of the target image is optimized through local weighted atlas voting. The obtained bone map is then used to assess the quality of deformed atlases to perform voxel-wise weighted atlas fusion. To evaluate the performance of the method, a leave-one-out cross-validation (LOOCV) scheme was devised to find optimal parameters for the model. Geometric evaluation of the produced pseudo-CT images and quantitative analysis of the accuracy of PET AC were performed. Moreover, a dosimetric evaluation of volumetric modulated arc therapy photon treatment plans calculated using the different pseudo-CT images was carried out and compared to those produced using CT images serving as references. The pseudo-CT images produced using the proposed method exhibit bone identification accuracy of 0.89 based on the Dice similarity metric compared to 0.75 achieved by the other atlas-based method. The superior bone extraction resulted in a mean standard uptake value bias of  -1.5  ±  5.0% (mean  ±  SD) in bony structures compared to  -19.9  ±  11.8% and  -8.1  ±  8.2% achieved by MRI segmentation-based (water

  5. Generalized INverse imaging (GIN): ultrafast fMRI with physiological noise correction.

    PubMed

    Boyacioğlu, Rasim; Barth, Markus

    2013-10-01

    An ultrafast functional magnetic resonance imaging (fMRI) technique, called generalized inverse imaging (GIN), is proposed, which combines inverse imaging with a phase constraint-leading to a less underdetermined reconstruction-and physiological noise correction. A single 3D echo planar imaging (EPI) prescan is sufficient to obtain the necessary coil sensitivity information and reference images that are used to reconstruct standard images, so that standard analysis methods are applicable. A moving dots stimulus paradigm was chosen to assess the performance of GIN. We find that the spatial localization of activation for GIN is comparable to an EPI protocol and that maximum z-scores increase significantly. The high temporal resolution of GIN (50 ms) and the acquisition of the phase information enable unaliased sampling and regression of physiological signals. Using the phase time courses obtained from the 32 channels of the receiver coils as nuisance regressors in a general linear model results in significant improvement of the functional activation, rendering the acquisition of external physiological signals unnecessary. The proposed physiological noise correction can in principle be used for other fMRI protocols, such as simultaneous multislice acquisitions, which acquire the phase information sufficiently fast and sample physiological signals unaliased.

  6. Manifold learning for image-based breathing gating in ultrasound and MRI.

    PubMed

    Wachinger, Christian; Yigitsoy, Mehmet; Rijkhorst, Erik-Jan; Navab, Nassir

    2012-05-01

    Respiratory motion is a challenging factor for image acquisition and image-guided procedures in the abdominal and thoracic region. In order to address the issues arising from respiratory motion, it is often necessary to detect the respiratory signal. In this article, we propose a novel, purely image-based retrospective respiratory gating method for ultrasound and MRI. Further, we apply this technique to acquire breathing-affected 4D ultrasound with a wobbler probe and, similarly, to create 4D MR with a slice stacking approach. We achieve the gating with Laplacian eigenmaps, a manifold learning technique, to determine the low-dimensional manifold embedded in the high-dimensional image space. Since Laplacian eigenmaps assign to each image frame a coordinate in low-dimensional space by respecting the neighborhood relationship, they are well suited for analyzing the breathing cycle. We perform the image-based gating on several 2D and 3D ultrasound datasets over time, and quantify its very good performance by comparing it to measurements from an external gating system. For MRI, we perform the manifold learning on several datasets for various orientations and positions. We achieve very high correlations by a comparison to an alternative gating with diaphragm tracking.

  7. Polyaspartic acid coated iron oxide nanoprobes for PET/MRI imaging.

    PubMed

    Cowger, Taku; Xie, Jin

    2013-01-01

    Iron oxide nanoparticles, due to their exceptional magnetic property, biocompatibility, and biodegradability, have long been studied as contrast agents for magnetic resonance imaging (Xie et al., Curr Med Chem 16(10):1278-1294, 2009; Xie et al., Adv Drug deliv Rev 62(11):1064-1079, 2010). While previous applications mostly target reticuloendothelial system (RES) organs such as liver and lymph nodes, recent efforts have been made to impart targeting peptides or antibodies onto particle surface to enable site-specific targeting after systemic administration (Xie et al., Adv Drug Deliv Rev 62(11):1064-1079, 2010; Cai and Chen, Small 3(11):1840-1854, 2007; Corot et al., Adv Drug Deliv Rev 58 (14):1471-1504, 2006; Xie et al., Acc Chem Res 44(10):883-892). Moreover, other imaging functionalities can be loaded onto nanoparticles to achieve multimodality imaging probes (Cai and Chen, Small 3(11):1840-1854, 2007; Lee et al., J Nucl Med Soc Nucl Med 49(8):1371-1379, 2008). In this protocol, we describe the procedure of constructing an iron oxide nanoparticle (IONP)-based probe with high affinity towards integrin αvβ3 for positron emission tomography (PET) and magnetic resonance imaging (MRI) dual modality imaging. The related characterizations and validation experiments, including particle concentration determination, Prussian blue staining, animal model preparation, and in vivo PET/MRI imaging will also be discussed.

  8. In Vivo Molecular MRI Imaging of Prostate Cancer by Targeting PSMA with Polypeptide-Labeled Superparamagnetic Iron Oxide Nanoparticles

    PubMed Central

    Zhu, Yunkai; Sun, Ying; Chen, Yaqing; Liu, Weiyong; Jiang, Jun; Guan, Wenbin; Zhang, Zhongyang; Duan, Yourong

    2015-01-01

    The prostate specific membrane antigen (PSMA) is broadly overexpressed on prostate cancer (PCa) cell surfaces. In this study, we report the synthesis, characterization, in vitro binding assay, and in vivo magnetic resonance imaging (MRI) evaluation of PSMA targeting superparamagnetic iron oxide nanoparticles (SPIONs). PSMA-targeting polypeptide CQKHHNYLC was conjugated to SPIONs to form PSMA-targeting molecular MRI contrast agents. In vitro studies demonstrated specific uptake of polypeptide-SPIONs by PSMA expressing cells. In vivo MRI studies found that MRI signals in PSMA-expressing tumors could be specifically enhanced with polypeptide-SPION, and further Prussian blue staining showed heterogeneous deposition of SPIONs in the tumor tissues. Taken altogether, we have developed PSMA-targeting polypeptide-SPIONs that could specifically enhance MRI signal in tumor-bearing mice, which might provide a new strategy for the molecular imaging of PCa. PMID:25927579

  9. NIFTY (NeuroImaging Functional Toolkit): an interactive program for functional MRI data processing and visualization

    NASA Astrophysics Data System (ADS)

    Arnholt, Jeff C.; Hanson, Dennis P.; Robb, Richard A.

    1995-05-01

    NIFTY (NeuroImaging Functional Toolkit) is a tool designed to perform quantitative analysis and visualization of neurofunctional magnetic resonance image (fMRI) data sets. NIFTY is an OSF/Motif application which utilizes the AVW (a visualization workshop) imaging library developed in our laboratory and includes algorithms for robust image registration, statistical analysis, and mapping of neurofunctional data sets. Anisotropic diffusion routines can be used to enhance the signal-to-noise- ratio of these images. Tools capable of histogram equalization, thresholding, volume rendering, atlas matching, and a large number of other functions can then be used to visualize the data. NIFTY's development will offer a robust and flexible system of essential functions integrated into an interactive, graphically-oriented program, allowing neuroscientists the means by which to process, visualize, and interpret their data.

  10. MRI of hand and wrist with a dedicated low field mini imager: preliminary report.

    PubMed

    Constantinesco, A; Brunot, B; Foucher, G

    1992-01-01

    In this paper we describe the development and the early results of an MRI system designed specifically for imaging of the hand and wrist. The imager takes up little space, uses a small 0.1 Tesla water-cooled electro-magnet with a vertical magnetic field and a 15 cm air gap. The system is based on a PC micro-computer and an integrated image processing board. There is no need for a Faraday cage. The image resolution is less than 1 mm using a 128 x 128 matrix format for a typical slice thickness of 3 mm. It is possible to achieve a 0.2 mm per pixel spatial resolution when imaging the fingers.

  11. Vision 20/20: Magnetic resonance imaging-guided attenuation correction in PET/MRI: Challenges, solutions, and opportunities

    SciTech Connect

    Mehranian, Abolfazl; Arabi, Hossein; Zaidi, Habib

    2016-03-15

    Attenuation correction is an essential component of the long chain of data correction techniques required to achieve the full potential of quantitative positron emission tomography (PET) imaging. The development of combined PET/magnetic resonance imaging (MRI) systems mandated the widespread interest in developing novel strategies for deriving accurate attenuation maps with the aim to improve the quantitative accuracy of these emerging hybrid imaging systems. The attenuation map in PET/MRI should ideally be derived from anatomical MR images; however, MRI intensities reflect proton density and relaxation time properties of biological tissues rather than their electron density and photon attenuation properties. Therefore, in contrast to PET/computed tomography, there is a lack of standardized global mapping between the intensities of MRI signal and linear attenuation coefficients at 511 keV. Moreover, in standard MRI sequences, bones and lung tissues do not produce measurable signals owing to their low proton density and short transverse relaxation times. MR images are also inevitably subject to artifacts that degrade their quality, thus compromising their applicability for the task of attenuation correction in PET/MRI. MRI-guided attenuation correction strategies can be classified in three broad categories: (i) segmentation-based approaches, (ii) atlas-registration and machine learning methods, and (iii) emission/transmission-based approaches. This paper summarizes past and current state-of-the-art developments and latest advances in PET/MRI attenuation correction. The advantages and drawbacks of each approach for addressing the challenges of MR-based attenuation correction are comprehensively described. The opportunities brought by both MRI and PET imaging modalities for deriving accurate attenuation maps and improving PET quantification will be elaborated. Future prospects and potential clinical applications of these techniques and their integration in commercial

  12. Vision 20/20: Magnetic resonance imaging-guided attenuation correction in PET/MRI: Challenges, solutions, and opportunities.

    PubMed

    Mehranian, Abolfazl; Arabi, Hossein; Zaidi, Habib

    2016-03-01

    Attenuation correction is an essential component of the long chain of data correction techniques required to achieve the full potential of quantitative positron emission tomography (PET) imaging. The development of combined PET/magnetic resonance imaging (MRI) systems mandated the widespread interest in developing novel strategies for deriving accurate attenuation maps with the aim to improve the quantitative accuracy of these emerging hybrid imaging systems. The attenuation map in PET/MRI should ideally be derived from anatomical MR images; however, MRI intensities reflect proton density and relaxation time properties of biological tissues rather than their electron density and photon attenuation properties. Therefore, in contrast to PET/computed tomography, there is a lack of standardized global mapping between the intensities of MRI signal and linear attenuation coefficients at 511 keV. Moreover, in standard MRI sequences, bones and lung tissues do not produce measurable signals owing to their low proton density and short transverse relaxation times. MR images are also inevitably subject to artifacts that degrade their quality, thus compromising their applicability for the task of attenuation correction in PET/MRI. MRI-guided attenuation correction strategies can be classified in three broad categories: (i) segmentation-based approaches, (ii) atlas-registration and machine learning methods, and (iii) emission/transmission-based approaches. This paper summarizes past and current state-of-the-art developments and latest advances in PET/MRI attenuation correction. The advantages and drawbacks of each approach for addressing the challenges of MR-based attenuation correction are comprehensively described. The opportunities brought by both MRI and PET imaging modalities for deriving accurate attenuation maps and improving PET quantification will be elaborated. Future prospects and potential clinical applications of these techniques and their integration in commercial

  13. The role of MRI in image-guided needle biopsy of focal bone and soft tissue neoplasms.

    PubMed

    Khoo, M M Y; Saifuddin, A

    2013-07-01

    Magnetic resonance imaging (MRI) plays a critical role in the management pathway of both soft tissue and bone neoplasms, from diagnosis through to post-treatment follow-up. There are a wide range of surgical, oncological, and combined treatment regimes but these rely on accurate histopathological diagnosis. This article reviews the role of MRI in the planning of image-guided needle biopsy for suspected soft tissue and bone tumors.

  14. Graph-based retrospective 4D image construction from free-breathing MRI slice acquisitions

    NASA Astrophysics Data System (ADS)

    Tong, Yubing; Udupa, Jayaram K.; Ciesielski, Krzysztof C.; McDonough, Joseph M.; Mong, Andrew; Campbell, Robert M.

    2014-03-01

    4D or dynamic imaging of the thorax has many potential applications [1, 2]. CT and MRI offer sufficient speed to acquire motion information via 4D imaging. However they have different constraints and requirements. For both modalities both prospective and retrospective respiratory gating and tracking techniques have been developed [3, 4]. For pediatric imaging, x-ray radiation becomes a primary concern and MRI remains as the de facto choice. The pediatric subjects we deal with often suffer from extreme malformations of their chest wall, diaphragm, and/or spine, as such patient cooperation needed by some of the gating and tracking techniques are difficult to realize without causing patient discomfort. Moreover, we are interested in the mechanical function of their thorax in its natural form in tidal breathing. Therefore free-breathing MRI acquisition is the ideal modality of imaging for these patients. In our set up, for each coronal (or sagittal) slice position, slice images are acquired at a rate of about 200-300 ms/slice over several natural breathing cycles. This produces typically several thousands of slices which contain both the anatomic and dynamic information. However, it is not trivial to form a consistent and well defined 4D volume from these data. In this paper, we present a novel graph-based combinatorial optimization solution for constructing the best possible 4D scene from such data entirely in the digital domain. Our proposed method is purely image-based and does not need breath holding or any external surrogates or instruments to record respiratory motion or tidal volume. Both adult and children patients' data are used to illustrate the performance of the proposed method. Experimental results show that the reconstructed 4D scenes are smooth and consistent spatially and temporally, agreeing with known shape and motion of the lungs.

  15. Iron-Loaded Magnetic Nanocapsules for pH-Triggered Drug Release and MRI Imaging

    PubMed Central

    2014-01-01

    Magnetic nanocapsules were synthesized for controlled drug release, magnetically assisted delivery, and MRI imaging. These magnetic nanocapsules, consisting of a stable iron nanocore and a mesoporous silica shell, were synthesized by controlled encapsulation of ellipsoidal hematite in silica, partial etching of the hematite core in acid, and reduction of the core by hydrogen. The iron core provided a high saturation magnetization and was stable against oxidation for at least 6 months in air and 1 month in aqueous solution. The hollow space between the iron core and mesoporous silica shell was used to load anticancer drug and a T1-weighted MRI contrast agent (Gd-DTPA). These multifunctional monodispersed magnetic “nanoeyes” were coated by multiple polyelectrolyte layers of biocompatible poly-l-lysine and sodium alginate to control the drug release as a function of pH. We studied pH-controlled release, magnetic hysteresis curves, and T1/T2 MRI contrast of the magnetic nanoeyes. They also served as MRI contrast agents with relaxivities of 8.6 mM–1 s–1 (r1) and 285 mM–1 s–1 (r2). PMID:24748722

  16. Dynamic Contrast-Enhanced MRI Perfusion Parameters as Imaging Biomarkers of Angiogenesis

    PubMed Central

    2016-01-01

    Hypoxia in the tumor microenvironment is the leading factor in angiogenesis. Angiogenesis can be identified by dynamic contrast-enhanced breast MRI (DCE MRI). Here we investigate the relationship between perfusion parameters on DCE MRI and angiogenic and prognostic factors in patients with invasive ductal carcinoma (IDC). Perfusion parameters (Ktrans, kep and ve) of 81 IDC were obtained using histogram analysis. Twenty-fifth, 50th and 75th percentile values were calculated and were analyzed for association with microvessel density (MVD), vascular endothelial growth factor (VEGF) and conventional prognostic factors. Correlation between MVD and ve50 was positive (r = 0.33). Ktrans50 was higher in tumors larger than 2 cm than in tumors smaller than 2 cm. In multivariate analysis, Ktrans50 was affected by tumor size and MVD with 12.8% explanation. There was significant association between Ktrans50 and tumor size and MVD. Therefore we conclude that DCE MRI perfusion parameters are potential imaging biomarkers for prediction of tumor angiogenesis and aggressiveness. PMID:28036342

  17. Synthesis of Gd2O3:Eu nanoplatelets for MRI and fluorescence imaging.

    PubMed

    Maalej, Nabil M; Qurashi, Ahsanulhaq; Assadi, Achraf Amir; Maalej, Ramzi; Shaikh, Mohammed Nasiruzzaman; Ilyas, Muhammad; Gondal, Mohammad A

    2015-01-01

    We synthesized Gd2O3 and Gd2O3 doped by europium (Eu) (2% to 10%) nanoplatelets using the polyol chemical method. The synthesized nanoplatelets were characterized by X-ray diffraction (XRD), FESEM, TEM, and EDX techniques. The optical properties of the synthesized nanoplatelets were investigated by photoluminescence spectroscopy. We also studied the magnetic resonance imaging (MRI) contrast enhancement of T1 relaxivity using 3 T MRI. The XRD for Gd2O3 revealed a cubic crystalline structure. The XRD of Gd2O3:Eu(3+) nanoplatelets were highly consistent with Gd2O3 indicating the total incorporation of the Eu(3+) ions in the Gd2O3 matrix. The Eu doping of Gd2O3 produced red luminescence around 612 nm corresponding to the radiative transitions from the Eu-excited state (5)D0 to the (7)F2. The photoluminescence was maximal at 5% Eu doping concentration. The stimulated CIE chromaticity coordinates were also calculated. Judd-Ofelt analysis was used to obtain the radiative properties of the sample from the emission spectra. The MRI contrast enhancement due to Gd2O3 was compared to DOTAREM commercial contrast agent at similar concentration of gadolinium oxide and provided similar contrast enhancement. The incorporation of Eu, however, decreased the MRI contrast due to replacement of gadolinium by Eu.

  18. Synthesis of Gd2O3:Eu nanoplatelets for MRI and fluorescence imaging

    NASA Astrophysics Data System (ADS)

    Maalej, Nabil M.; Qurashi, Ahsanulhaq; Assadi, Achraf Amir; Maalej, Ramzi; Shaikh, Mohammed Nasiruzzaman; Ilyas, Muhammad; Gondal, Mohammad A.

    2015-05-01

    We synthesized Gd2O3 and Gd2O3 doped by europium (Eu) (2% to 10%) nanoplatelets using the polyol chemical method. The synthesized nanoplatelets were characterized by X-ray diffraction (XRD), FESEM, TEM, and EDX techniques. The optical properties of the synthesized nanoplatelets were investigated by photoluminescence spectroscopy. We also studied the magnetic resonance imaging (MRI) contrast enhancement of T1 relaxivity using 3 T MRI. The XRD for Gd2O3 revealed a cubic crystalline structure. The XRD of Gd2O3:Eu3+ nanoplatelets were highly consistent with Gd2O3 indicating the total incorporation of the Eu3+ ions in the Gd2O3 matrix. The Eu doping of Gd2O3 produced red luminescence around 612 nm corresponding to the radiative transitions from the Eu-excited state 5D0 to the 7F2. The photoluminescence was maximal at 5% Eu doping concentration. The stimulated CIE chromaticity coordinates were also calculated. Judd-Ofelt analysis was used to obtain the radiative properties of the sample from the emission spectra. The MRI contrast enhancement due to Gd2O3 was compared to DOTAREM commercial contrast agent at similar concentration of gadolinium oxide and provided similar contrast enhancement. The incorporation of Eu, however, decreased the MRI contrast due to replacement of gadolinium by Eu.

  19. Automated Robust Image Segmentation: Level Set Method Using Nonnegative Matrix Factorization with Application to Brain MRI.

    PubMed

    Dera, Dimah; Bouaynaya, Nidhal; Fathallah-Shaykh, Hassan M

    2016-07-01

    We address the problem of fully automated region discovery and robust image segmentation by devising a new deformable model based on the level set method (LSM) and the probabilistic nonnegative matrix factorization (NMF). We describe the use of NMF to calculate the number of distinct regions in the image and to derive the local distribution of the regions, which is incorporated into the energy functional of the LSM. The results demonstrate that our NMF-LSM method is superior to other approaches when applied to synthetic binary and gray-scale images and to clinical magnetic resonance images (MRI) of the human brain with and without a malignant brain tumor, glioblastoma multiforme. In particular, the NMF-LSM method is fully automated, highly accurate, less sensitive to the initial selection of the contour(s) or initial conditions, more robust to noise and model parameters, and able to detect as small distinct regions as desired. These advantages stem from the fact that the proposed method relies on histogram information instead of intensity values and does not introduce nuisance model parameters. These properties provide a general approach for automated robust region discovery and segmentation in heterogeneous images. Compared with the retrospective radiological diagnoses of two patients with non-enhancing grade 2 and 3 oligodendroglioma, the NMF-LSM detects earlier progression times and appears suitable for monitoring tumor response. The NMF-LSM method fills an important need of automated segmentation of clinical MRI.

  20. Automatic image-driven segmentation of cardiac ventricles in cine anatomical MRI

    NASA Astrophysics Data System (ADS)

    Cocosco, Chris A.; Niessen, Wiro J.; Netsch, Thomas; Vonken, Evert-jan P. A.; Viergever, Max A.

    2005-08-01

    The automatic segmentation of the heart's two ventricles from dynamic ("cine") cardiac anatomical images, such as 3D+time short-axis MRI, is of significant clinical importance. Previously published automated methods have various disadvantages for routine clinical use. This work reports about a novel automatic segmentation method that is very fast, and robust against anatomical variability and image contrast variations. The method is mostly image-driven: it fully exploits the information provided by modern 4D (3D+time) balanced Fast Field Echo (bFFE) cardiac anatomical MRI, and makes only few and plausible assumptions about the images and the imaged heart. Specifically, the method does not need any geometrical shape models nor complex gray-level appearance models. The method simply uses the two ventricles' contraction-expansion cycle, as well as the ventricles' spatial coherence along the time dimension. The performance of the cardiac ventricles segmentation method was demonstrated through a qualitative visual validation on 32 clinical exams: no gross failures for the left-ventricle (right-ventricle) on 32 (30) of the exams were found. Also, a clinical validation of resulting quantitative cardiac functional parameters was performed against a manual quantification of 18 exams; the automatically computed Ejection Fraction (EF) correlated well to the manually computed one: linear regression with RMS=3.7% (RMS expressed in EF units).

  1. Combination of Compressed Sensing and Parallel Imaging for Highly Accelerated First-Pass Cardiac Perfusion MRI

    PubMed Central

    Otazo, Ricardo; Kim, Daniel; Axel, Leon; Sodickson, Daniel K.

    2010-01-01

    First-pass cardiac perfusion MRI is a natural candidate for compressed sensing acceleration since its representation in the combined temporal Fourier and spatial domain is sparse and the required incoherence can be effectively accomplished by k-t random undersampling. However, the required number of samples in practice (three to five times the number of sparse coefficients) limits the acceleration for compressed sensing alone. Parallel imaging may also be used to accelerate cardiac perfusion MRI, with acceleration factors ultimately limited by noise amplification. In this work, compressed sensing and parallel imaging are combined by merging the k-t SPARSE technique with SENSE reconstruction to substantially increase the acceleration rate for perfusion imaging. We also present a new theoretical framework for understanding the combination of k-t SPARSE with SENSE based on distributed compressed sensing theory. This framework, which identifies parallel imaging as a distributed multisensor implementation of compressed sensing, enables an estimate of feasible acceleration for the combined approach. We demonstrate feasibility of 8-fold acceleration in vivo with whole-heart coverage and high spatial and temporal resolution using standard coil arrays. The method is relatively insensitive to respiratory motion artifacts and presents similar temporal fidelity and image quality when compared to GRAPPA with 2-fold acceleration. PMID:20535813

  2. Characterizing growth patterns in longitudinal MRI using image contrast

    NASA Astrophysics Data System (ADS)

    Vardhan, Avantika; Prastawa, Marcel; Vachet, Clement; Piven, Joseph; Gerig, Guido

    2014-03-01

    Understanding the growth patterns of the early brain is crucial to the study of neuro-development. In the early stages of brain growth, a rapid sequence of biophysical and chemical processes take place. A crucial component of these processes, known as myelination, consists of the formation of a myelin sheath around a nerve fiber, enabling the effective transmission of neural impulses. As the brain undergoes myelination, there is a subsequent change in the contrast between gray matter and white matter as observed in MR scans. In this work, gray-white matter contrast is proposed as an effective measure of appearance which is relatively invariant to location, scanner type, and scanning conditions. To validate this, contrast is computed over various cortical regions for an adult human phantom. MR (Magnetic Resonance) images of the phantom were repeatedly generated using different scanners, and at different locations. Contrast displays less variability over changing conditions of scan compared to intensity-based measures, demonstrating that it is less dependent than intensity on external factors. Additionally, contrast is used to analyze longitudinal MR scans of the early brain, belonging to healthy controls and Down's Syndrome (DS) patients. Kernel regression is used to model subject-specific trajectories of contrast changing with time. Trajectories of contrast changing with time, as well as time-based biomarkers extracted from contrast modeling, show large differences between groups. The preliminary applications of contrast based analysis indicate its future potential to reveal new information not covered by conventional volumetric or deformation-based analysis, particularly for distinguishing between normal and abnormal growth patterns.

  3. Functional imaging of murine hearts using accelerated self-gated UTE cine MRI.

    PubMed

    Motaal, Abdallah G; Noorman, Nils; de Graaf, Wolter L; Hoerr, Verena; Florack, Luc M J; Nicolay, Klaas; Strijkers, Gustav J

    2015-01-01

    We introduce a fast protocol for ultra-short echo time (UTE) Cine magnetic resonance imaging (MRI) of the beating murine heart. The sequence involves a self-gated UTE with golden-angle radial acquisition and compressed sensing reconstruction. The self-gated acquisition is performed asynchronously with the heartbeat, resulting in a randomly undersampled kt-space that facilitates compressed sensing reconstruction. The sequence was tested in 4 healthy rats and 4 rats with chronic myocardial infarction, approximately 2 months after surgery. As a control, a non-accelerated self-gated multi-slice FLASH sequence with an echo time (TE) of 2.76 ms, 4.5 signal averages, a matrix of 192 × 192, and an acquisition time of 2 min 34 s per slice was used to obtain Cine MRI with 15 frames per heartbeat. Non-accelerated UTE MRI was performed with TE = 0.29 ms, a reconstruction matrix of 192 × 192, and an acquisition time of 3 min 47 s per slice for 3.5 averages. Accelerated imaging with 2×, 4× and 5× undersampled kt-space data was performed with 1 min, 30 and 15 s acquisitions, respectively. UTE Cine images up to 5× undersampled kt-space data could be successfully reconstructed using a compressed sensing algorithm. In contrast to the FLASH Cine images, flow artifacts in the UTE images were nearly absent due to the short echo time, simplifying segmentation of the left ventricular (LV) lumen. LV functional parameters derived from the control and the accelerated Cine movies were statistically identical.

  4. An image acquisition and registration strategy for the fusion of hyperpolarized helium-3 MRI and x-ray CT images of the lung

    NASA Astrophysics Data System (ADS)

    Ireland, Rob H.; Woodhouse, Neil; Hoggard, Nigel; Swinscoe, James A.; Foran, Bernadette H.; Hatton, Matthew Q.; Wild, Jim M.

    2008-11-01

    The purpose of this ethics committee approved prospective study was to evaluate an image acquisition and registration protocol for hyperpolarized helium-3 magnetic resonance imaging (3He-MRI) and x-ray computed tomography. Nine patients with non-small cell lung cancer (NSCLC) gave written informed consent to undergo a free-breathing CT, an inspiration breath-hold CT and a 3D ventilation 3He-MRI in CT position using an elliptical birdcage radiofrequency (RF) body coil. 3He-MRI to CT image fusion was performed using a rigid registration algorithm which was assessed by two observers using anatomical landmarks and a percentage volume overlap coefficient. Registration of 3He-MRI to breath-hold CT was more accurate than to free-breathing CT; overlap 82.9 ± 4.2% versus 59.8 ± 9.0% (p < 0.001) and mean landmark error 0.75 ± 0.24 cm versus 1.25 ± 0.60 cm (p = 0.002). Image registration is significantly improved by using an imaging protocol that enables both 3He-MRI and CT to be acquired with similar breath holds and body position through the use of a birdcage 3He-MRI body RF coil and an inspiration breath-hold CT. Fusion of 3He-MRI to CT may be useful for the assessment of patients with lung diseases.

  5. MRI-guided fiber-based fluorescence molecular tomography for preclinical atherosclerosis imaging

    NASA Astrophysics Data System (ADS)

    Li, Baoqiang; Pouliot, Philippe; Lesage, Frederic

    2014-09-01

    Multi-modal imaging combining fluorescent molecular tomography (FMT) with MRI could provide information in these two modalities as well as optimize the recovery of functional information with MR-guidance. Here, we present a MRI-guided FMT system. An optical probe was designed consisting of a fiber plate on the top and bottom sides of the animal bed, respectively. In experiment, animal was installed between the two plates. Mounting fibers on each plate, transmission measuring could be conducted from both sides of the animal. Moreover, an accurate fluorescence reconstruction was achieved with MRI-derived anatomical guidance. The sensitivity of the FMT system was evaluated with a phantom showing that with long fibers, it was sufficient to detect 10nM Cy5.5 solution with ~28.5 dB in the phantom. The system was eventually used to image MMP activity involved in atherosclerosis with two ATX mice and two control mice. The reconstruction results were in agreement with ex vivo measurement.

  6. Simultaneous Quantitative Imaging of Electrical Properties and Proton Density from B1 Maps Using MRI.

    PubMed

    Liu, Jiaen; Van de Moortele, Pierre-Francois; Zhang, Xiaotong; Wang, Yicun; He, Bin

    2016-03-29

    Electrical conductivity and permittivity of biological tissues are important diagnostic parameters and are useful for calculating subject-specific specific absorption rate distribution. On the other hand, water proton density also has clinical relevance for diagnosis purposes. These two kinds of tissue properties are inevitably associated in the technique of electrical properties tomography (EPT), which can be used to map in vivo electrical properties based on the measured B1 field distribution at Larmor frequency using magnetic resonance imaging (MRI). The signal magnitude in MR images is locally proportional to both the proton density of tissue and the receive B1 field; this is a source of artifact in receive B1-based EPT reconstruction because these two quantities cannot easily be disentangled. In this study, a new method was proposed for simultaneously extracting quantitative conductivity, permittivity and proton density from the measured magnitude of transmit B1 field, proton density-weighted receive B1 field, and transceiver phase, in a multi-channel radiofrequency (RF) coil using MRI, without specific assumptions to derive the proton density distribution. We evaluated the spatial resolution, sensitivity to contrast, and accuracy of the method using numerical simulations of B1 field in a phantom and in a realistic human head model. Using the proposed method, conductivity, permittivity and proton density were then experimentally obtained ex vivo in a pork tissue sample on a 7T MRI scanner equipped with a 16-channel microstrip transceiver RF coil.

  7. Simultaneous Quantitative Imaging of Electrical Properties and Proton Density From B1 Maps Using MRI.

    PubMed

    Jiaen Liu; Van de Moortele, Pierre-Francois; Xiaotong Zhang; Yicun Wang; Bin He

    2016-09-01

    Electrical conductivity and permittivity of biological tissues are important diagnostic parameters and are useful for calculating subject-specific specific absorption rate distribution. On the other hand, water proton density also has clinical relevance for diagnosis purposes. These two kinds of tissue properties are inevitably associated in the technique of electrical properties tomography (EPT), which can be used to map in vivo electrical properties based on the measured B1 field distribution at Larmor frequency using magnetic resonance imaging (MRI). The signal magnitude in MR images is locally proportional to both the proton density of tissue and the receive B1 field; this is a source of artifact in receive B1-based EPT reconstruction because these two quantities cannot easily be disentangled. In this study, a new method was proposed for simultaneously extracting quantitative conductivity, permittivity and proton density from the measured magnitude of transmit B1 field, proton density-weighted receive B1 field, and transceiver phase, in a multi-channel radiofrequency (RF) coil using MRI, without specific assumptions to derive the proton density distribution. We evaluated the spatial resolution, sensitivity to contrast, and accuracy of the method using numerical simulations of B1 field in a phantom and in a realistic human head model. Using the proposed method, conductivity, permittivity and proton density were then experimentally obtained ex vivo in a pork tissue sample on a 7T MRI scanner equipped with a 16-channel microstrip transceiver RF coil.

  8. Imaging the accumulation and suppression of tau pathology using multiparametric MRI

    PubMed Central

    Holmes, Holly E.; Colgan, Niall; Ismail, Ozama; Ma, Da; Powell, Nick M.; O'Callaghan, James M.; Harrison, Ian F.; Johnson, Ross A.; Murray, Tracey K.; Ahmed, Zeshan; Heggenes, Morton; Fisher, Alice; Cardoso, M.J.; Modat, Marc; Walker-Samuel, Simon; Fisher, Elizabeth M.C.; Ourselin, Sebastien; O'Neill, Michael J.; Wells, Jack A.; Collins, Emily C.; Lythgoe, Mark F.

    2016-01-01

    Mouse models of Alzheimer's disease have served as valuable tools for investigating pathogenic mechanisms relating to neurodegeneration, including tau-mediated and neurofibrillary tangle pathology—a major hallmark of the disease. In this work, we have used multiparametric magnetic resonance imaging (MRI) in a longitudinal study of neurodegeneration in the rTg4510 mouse model of tauopathy, a subset of which were treated with doxycycline at different time points to suppress the tau transgene. Using this paradigm, we investigated the sensitivity of multiparametric MRI to both the accumulation and suppression of pathologic tau. Tau-related atrophy was discernible from 5.5 months within the cortex and hippocampus. We observed markedly less atrophy in the treated rTg4510 mice, which was enhanced after doxycycline intervention from 3.5 months. We also observed differences in amide proton transfer, cerebral blood flow, and diffusion tensor imaging parameters in the rTg4510 mice, which were significantly less altered after doxycycline treatment. We propose that these non-invasive MRI techniques offer insight into pathologic mechanisms underpinning Alzheimer's disease that may be important when evaluating emerging therapeutics targeting one of more of these processes. PMID:26923415

  9. Evaluating kurtosis-based diffusion MRI tissue models for white matter with fiber ball imaging.

    PubMed

    Jensen, Jens H; McKinnon, Emilie T; Glenn, G Russell; Helpern, Joseph A

    2017-01-13

    In order to quantify well-defined microstructural properties of brain tissue from diffusion MRI (dMRI) data, tissue models are typically employed that relate biological features, such as cell morphology and cell membrane permeability, to the diffusion dynamics. A variety of such models have been proposed for white matter, and their validation is a topic of active interest. In this paper, three different tissue models are tested by comparing their predictions for a specific microstructural parameter to a value measured independently with a recently proposed dMRI method known as fiber ball imaging (FBI). The three tissue models are all constructed with the diffusion and kurtosis tensors, and they are hence compatible with diffusional kurtosis imaging. Nevertheless, the models differ significantly in their details and predictions. For voxels with fractional anisotropies (FAs) exceeding 0.5, all three are reasonably consistent with FBI. However, for lower FA values, one of these, called the white matter tract integrity (WMTI) model, is found to be in much better accord with FBI than the other two, suggesting that the WMTI model has a broader range of applicability.

  10. Masking Level Differences – A Diffusion Tensor Imaging and Functional MRI Study

    PubMed Central

    Wack, David S.; Polak, Paul; Furuyama, Jon; Burkard, Robert F.

    2014-01-01

    In our previous study we investigated Masking Level Differences (MLD) using functional Magnetic Resonance Imaging (fMRI), but were unable to confirm neural correlations for the MLD within the auditory cortex and inferior colliculus. Here we have duplicated conditions from our previous study, but have included more participants and changed the study site to a new location with a newer scanner and presentation system. Additionally, Diffusion Tensor Imaging (DTI) is included to allow investigation of fiber tracts that may be involved with MLDs. Twenty participants were included and underwent audiometric testing and MRI scanning. The current study revealed regions of increased and decreased activity within the auditory cortex when comparing the combined noise and signal of the dichotic MLD stimuli (N0Sπ and NπS0) with N0S0. Furthermore, we found evidence of inferior colliculus involvement. Our DTI findings show strong correlations between DTI measures within the brainstem and signal detection threshold levels. Patterns of correlation when the signal was presented only to the right ear showed an extensive network in the left hemisphere; however, the opposite was not true for the signal presented only to the left ear. Our current study was able to confirm what we had previously hypothesized using fMRI, while extending our investigation of MLDs to include the characteristics of connecting neural pathways. PMID:24558392

  11. Imaging of acute myocardial infarction in pigs with Indium-111 monoclonal antimyosin scintigraphy and MRI

    SciTech Connect

    ten Kate, C.I.; van Kroonenburgh, M.J.; Schipperheyn, J.J.; Doornbos, J.; Hoedemaeker, P.J.; Maes, A.; v.d. Nat, K.H.; Camps, J.A.; Huysmans, H.A.; Pauwels, E.K. )

    1990-07-01

    Indium-111 antimyosin F(ab')2 was used in a series of scintigraphic studies on experimentally induced myocardial infarctions in pigs. Antimyosin distribution recorded by planar images of in vivo pigs and by single photon emission computed tomography (SPECT) of excised hearts delineated areas of myocardial necrosis if infarct volume exceeded 3.3 cm3. Scintigraphic images were compared with magnetic resonance images (MRI) obtained from excised hearts and with photographs of slices of the hearts. Infarct size and localization determined with antimyosin were compared. The MR images, with or without gadolinium-DTPA (Gd-DTPA), of the in vivo pigs were all false-negative; some myocardial wall thinning and high bloodpool signals were visible. Results show that both the antimyosin and the MR technique are specific methods for the visualization of induced myocardial necrosis in this animal model. However, the use of antimyosin is limited to a period ranging from 24 to 72 hours after infarction.

  12. Voltage-based Device Tracking in a 1.5 Tesla MRI during Imaging: Initial validation in swine models

    PubMed Central

    Schmidt, Ehud J; Tse, Zion TH; Reichlin, Tobias R; Michaud, Gregory F; Watkins, Ronald D; Butts-Pauly, Kim; Kwong, Raymond Y; Stevenson, William; Schweitzer, Jeffrey; Byrd, Israel; Dumoulin, Charles L

    2013-01-01

    Purpose Voltage-based device-tracking (VDT) systems are commonly used for tracking invasive devices in electrophysiological (EP) cardiac-arrhythmia therapy. During EP procedures, electro-anatomic-mapping (EAM) workstations provide guidance by integrating VDT location and intra-cardiac-ECG information with X-ray, CT, Ultrasound, and MR images. MR assists navigation, mapping and radio-frequency-ablation. Multi-modality interventions require multiple patient transfers between an MRI and the X-ray/ultrasound EP suite, increasing the likelihood of patient-motion and image mis-registration. An MRI-compatible VDT system may increase efficiency, since there is currently no single method to track devices both inside and outside the MRI scanner. Methods An MRI-compatible VDT system was constructed by modifying a commercial system. Hardware was added to reduce MRI gradient-ramp and radio-frequency-unblanking-pulse interference. VDT patches and cables were modified to reduce heating. Five swine cardiac VDT EAM-mapping interventions were performed, navigating inside and thereafter outside the MRI. Results Three-catheter VDT interventions were performed at >12 frames-per-second both inside and outside the MRI scanner with <3mm error. Catheters were followed on VDT- and MRI-derived maps. Simultaneous VDT and imaging was possible in repetition-time (TR) >32 msec sequences with <0.5mm errors, and <5% MRI SNR loss. At shorter TRs, only intra-cardiac-ECG was reliable. RF Heating was <1.5C°. Conclusion An MRI-compatible VDT system is feasible. PMID:23580479

  13. Glucosamine and N-acetyl glucosamine as new CEST MRI agents for molecular imaging of tumors

    PubMed Central

    Rivlin, Michal; Navon, Gil

    2016-01-01

    The efficacy of glucosamine (GlcN) and N-acetyl glucosamine (GlcNAc) as agents for chemical exchange saturation transfer (CEST) magnetic resonance molecular imaging of tumors is demonstrated. Both agents reflect the metabolic activity and malignancy of the tumors. The method was tested in two types of tumors implanted orthotopically in mice: 4T1 (mouse mammary cancer cells) and MCF7 (human mammary cancer cells). 4T1 is a more aggressive type of tumor than MCF7 and exhibited a larger CEST effect. Two methods of administration of the agents, intravenous (IV) and oral (PO), gave similar results. The CEST MRI observation of lung metastasis was confirmed by histology. The potential of the clinical application of CEST MRI with these agents for cancer diagnosis is strengthened by their lack of toxicity as can be indicated from their wide use as food supplements. PMID:27600054

  14. Liquid-state carbon-13 hyperpolarization generated in an MRI system for fast imaging

    PubMed Central

    Schmidt, A. B.; Berner, S.; Schimpf, W.; Müller, C.; Lickert, T.; Schwaderlapp, N.; Knecht, S.; Skinner, J. G.; Dost, A.; Rovedo, P.; Hennig, J.; von Elverfeldt, D.; Hövener, J. -B.

    2017-01-01

    Hyperpolarized (HP) tracers dramatically increase the sensitivity of magnetic resonance imaging (MRI) to monitor metabolism non-invasively and in vivo. Their production, however, requires an extra polarizing device (polarizer) whose complexity, operation and cost can exceed that of an MRI system itself. Furthermore, the lifetime of HP tracers is short and some of the enhancement is lost during transfer to the application site. Here, we present the production of HP tracers in water without an external polarizer: by Synthesis Amid the Magnet Bore, A Dramatically Enhanced Nuclear Alignment (SAMBADENA) is achieved within seconds, corresponding to a hyperpolarization of ∼20%. As transfer of the tracer is no longer required, SAMBADENA may permit a higher polarization at the time of detection at a fraction of the cost and complexity of external polarizers. This development is particularly promising in light of the recently extended portfolio of biomedically relevant para-hydrogen-tracers and may lead to new diagnostic applications. PMID:28262691

  15. MRI 3D CISS– A Novel Imaging Modality in Diagnosing Trigeminal Neuralgia – A Review

    PubMed Central

    Besta, Radhika; Shankar, Y. Uday; Kumar, Ashwini; Prakash, S. Bhanu

    2016-01-01

    Trigeminal Neuralgia (TN) is considered as one of the most painful neurologic disorders affecting oro-facial region. TN is often diagnosed clinically based on the patients complete history of pain (severity, duration, episodes etc), relief of pain on test dose of Carbamazepine, regional block of long acting anaesthetic. However, Magnetic Resonance Imaging (MRI) plays an important and confirmatory role in showing Neuro Vascular Conflict (NVC) which is the commonest causative factor for TN. This article reviews the effectiveness of three-dimensional constructive interference in steady-state (3D-CISS) MRI in diagnosing the exact location, degree of neurovascular conflict responsible for classical as well as atypical TN and possible pre-treatment evaluation and treatment outcome. PMID:27135019

  16. Liquid-state carbon-13 hyperpolarization generated in an MRI system for fast imaging

    NASA Astrophysics Data System (ADS)

    Schmidt, A. B.; Berner, S.; Schimpf, W.; Müller, C.; Lickert, T.; Schwaderlapp, N.; Knecht, S.; Skinner, J. G.; Dost, A.; Rovedo, P.; Hennig, J.; von Elverfeldt, D.; Hövener, J.-B.

    2017-03-01

    Hyperpolarized (HP) tracers dramatically increase the sensitivity of magnetic resonance imaging (MRI) to monitor metabolism non-invasively and in vivo. Their production, however, requires an extra polarizing device (polarizer) whose complexity, operation and cost can exceed that of an MRI system itself. Furthermore, the lifetime of HP tracers is short and some of the enhancement is lost during transfer to the application site. Here, we present the production of HP tracers in water without an external polarizer: by Synthesis Amid the Magnet Bore, A Dramatically Enhanced Nuclear Alignment (SAMBADENA) is achieved within seconds, corresponding to a hyperpolarization of ~20%. As transfer of the tracer is no longer required, SAMBADENA may permit a higher polarization at the time of detection at a fraction of the cost and complexity of external polarizers. This development is particularly promising in light of the recently extended portfolio of biomedically relevant para-hydrogen-tracers and may lead to new diagnostic applications.

  17. Breast density quantification using magnetic resonance imaging (MRI) with bias field correction: A postmortem study

    SciTech Connect

    Ding, Huanjun; Johnson, Travis; Lin, Muqing; Le, Huy Q.; Ducote, Justin L.; Su, Min-Ying; Molloi, Sabee

    2013-12-15

    Purpose: Quantification of breast density based on three-dimensional breast MRI may provide useful information for the early detection of breast cancer. However, the field inhomogeneity can severely challenge the computerized image segmentation process. In this work, the effect of the bias field in breast density quantification has been investigated with a postmortem study. Methods: T1-weighted images of 20 pairs of postmortem breasts were acquired on a 1.5 T breast MRI scanner. Two computer-assisted algorithms were used to quantify the volumetric breast density. First, standard fuzzy c-means (FCM) clustering was used on raw images with the bias field present. Then, the coherent local intensity clustering (CLIC) method estimated and corrected the bias field during the iterative tissue segmentation process. Finally, FCM clustering was performed on the bias-field-corrected images produced by CLIC method. The left–right correlation for breasts in the same pair was studied for both segmentation algorithms to evaluate the precision of the tissue classification. Finally, the breast densities measured with the three methods were compared to the gold standard tissue compositions obtained from chemical analysis. The linear correlation coefficient, Pearson'sr, was used to evaluate the two image segmentation algorithms and the effect of bias field. Results: The CLIC method successfully corrected the intensity inhomogeneity induced by the bias field. In left–right comparisons, the CLIC method significantly improved the slope and the correlation coefficient of the linear fitting for the glandular volume estimation. The left–right breast density correlation was also increased from 0.93 to 0.98. When compared with the percent fibroglandular volume (%FGV) from chemical analysis, results after bias field correction from both the CLIC the FCM algorithms showed improved linear correlation. As a result, the Pearson'sr increased from 0.86 to 0.92 with the bias field correction

  18. Breast density quantification using magnetic resonance imaging (MRI) with bias field correction: A postmortem study

    PubMed Central

    Ding, Huanjun; Johnson, Travis; Lin, Muqing; Le, Huy Q.; Ducote, Justin L.; Su, Min-Ying; Molloi, Sabee

    2013-01-01

    Purpose: Quantification of breast density based on three-dimensional breast MRI may provide useful information for the early detection of breast cancer. However, the field inhomogeneity can severely challenge the computerized image segmentation process. In this work, the effect of the bias field in breast density quantification has been investigated with a postmortem study. Methods: T1-weighted images of 20 pairs of postmortem breasts were acquired on a 1.5 T breast MRI scanner. Two computer-assisted algorithms were used to quantify the volumetric breast density. First, standard fuzzy c-means (FCM) clustering was used on raw images with the bias field present. Then, the coherent local intensity clustering (CLIC) method estimated and corrected the bias field during the iterative tissue segmentation process. Finally, FCM clustering was performed on the bias-field-corrected images produced by CLIC method. The left–right correlation for breasts in the same pair was studied for both segmentation algorithms to evaluate the precision of the tissue classification. Finally, the breast densities measured with the three methods were compared to the gold standard tissue compositions obtained from chemical analysis. The linear correlation coefficient, Pearson's r, was used to evaluate the two image segmentation algorithms and the effect of bias field. Results: The CLIC method successfully corrected the intensity inhomogeneity induced by the bias field. In left–right comparisons, the CLIC method significantly improved the slope and the correlation coefficient of the linear fitting for the glandular volume estimation. The left–right breast density correlation was also increased from 0.93 to 0.98. When compared with the percent fibroglandular volume (%FGV) from chemical analysis, results after bias field correction from both the CLIC the FCM algorithms showed improved linear correlation. As a result, the Pearson's r increased from 0.86 to 0.92 with the bias field correction

  19. Imaging of prostate cancer: a platform for 3D co-registration of in-vivo MRI ex-vivo MRI and pathology

    NASA Astrophysics Data System (ADS)

    Orczyk, Clément; Mikheev, Artem; Rosenkrantz, Andrew; Melamed, Jonathan; Taneja, Samir S.; Rusinek, Henry

    2012-02-01

    Objectives: Multi-parametric MRI is emerging as a promising method for prostate cancer diagnosis. prognosis and treatment planning. However, the localization of in-vivo detected lesions and pathologic sites of cancer remains a significant challenge. To overcome this limitation we have developed and tested a system for co-registration of in-vivo MRI, ex-vivo MRI and histology. Materials and Methods: Three men diagnosed with localized prostate cancer (ages 54-72, PSA levels 5.1-7.7 ng/ml) were prospectively enrolled in this study. All patients underwent 3T multi-parametric MRI that included T2W, DCEMRI, and DWI prior to robotic-assisted prostatectomy. Ex-vivo multi-parametric MRI was performed on fresh prostate specimen. Excised prostates were then sliced at regular intervals and photographed both before and after fixation. Slices were perpendicular to the main axis of the posterior capsule, i.e., along the direction of the rectal wall. Guided by the location of the urethra, 2D digital images were assembled into 3D models. Cancer foci, extra-capsular extensions and zonal margins were delineated by the pathologist and included in 3D histology data. A locally-developed software was applied to register in-vivo, ex-vivo and histology using an over-determined set of anatomical landmarks placed in anterior fibro-muscular stroma, central. transition and peripheral zones. The mean root square distance across corresponding control points was used to assess co-registration error. Results: Two specimens were pT3a and one pT2b (negative margin) at pathology. The software successfully fused invivo MRI. ex-vivo MRI fresh specimen and histology using appropriate (rigid and affine) transformation models with mean square error of 1.59 mm. Coregistration accuracy was confirmed by multi-modality viewing using operator-guided variable transparency. Conclusion: The method enables successful co-registration of pre-operative MRI, ex-vivo MRI and pathology and it provides initial evidence

  20. Prediction of standard-dose brain PET image by using MRI and low-dose brain [{sup 18}F]FDG PET images

    SciTech Connect

    Kang, Jiayin; Gao, Yaozong; Shi, Feng; Lalush, David S.; Lin, Weili; Shen, Dinggang

    2015-09-15

    Purpose: Positron emission tomography (PET) is a nuclear medical imaging technology that produces 3D images reflecting tissue metabolic activity in human body. PET has been widely used in various clinical applications, such as in diagnosis of brain disorders. High-quality PET images play an essential role in diagnosing brain diseases/disorders. In practice, in order to obtain high-quality PET images, a standard-dose radionuclide (tracer) needs to be used and injected into a living body. As a result, it will inevitably increase the patient’s exposure to radiation. One solution to solve this problem is predicting standard-dose PET images using low-dose PET images. As yet, no previous studies with this approach have been reported. Accordingly, in this paper, the authors propose a regression forest based framework for predicting a standard-dose brain [{sup 18}F]FDG PET image by using a low-dose brain [{sup 18}F]FDG PET image and its corresponding magnetic resonance imaging (MRI) image. Methods: The authors employ a regression forest for predicting the standard-dose brain [{sup 18}F]FDG PET image by low-dose brain [{sup 18}F]FDG PET and MRI images. Specifically, the proposed method consists of two main steps. First, based on the segmented brain tissues (i.e., cerebrospinal fluid, gray matter, and white matter) in the MRI image, the authors extract features for each patch in the brain image from both low-dose PET and MRI images to build tissue-specific models that can be used to initially predict standard-dose brain [{sup 18}F]FDG PET images. Second, an iterative refinement strategy, via estimating the predicted image difference, is used to further improve the prediction accuracy. Results: The authors evaluated their algorithm on a brain dataset, consisting of 11 subjects with MRI, low-dose PET, and standard-dose PET images, using leave-one-out cross-validations. The proposed algorithm gives promising results with well-estimated standard-dose brain [{sup 18}F]FDG PET

  1. Noninvasive MRI-SERS Imaging in Living Mice Using an Innately Bimodal Nanomaterial

    PubMed Central

    Yigit, Mehmet V.; Zhu, Leyun; Ifediba, Marytheresa A.; Zhang, Yong; Carr, Kevin; Moore, Anna; Medarova, Zdravka

    2011-01-01

    We report a novel nanomaterial (AuMN-DTTC) that can be used as a bimodal contrast agent for in vivo magnetic resonance imaging (MRI) and Raman spectroscopy. The probe consists of MRI-active superparamagnetic iron oxide nanoparticles, stably complexed with gold nanostructures. The gold component serves as a substrate for a Raman active dye molecule to generate a surface-enhanced Raman scattering (SERS) effect. The synthesized probe produces T2 weighted contrast and can be used as a SERS active material both in silico (in aqueous solution) and in vivo. A quantitative assessment of T2 relaxation times was obtained using multiecho MRI analysis. The T2 relaxation times of AuMN-DTTC and MN (dextran-coated iron oxide nanoparticles) were 29.23 + 1.45, and 31.58 + 1.7 msec, respectively. The SERS signature of AuMN-DTTC revealed peaks at 508, 629, 782, 844, 1080, 1108, 1135, and 1242 cm−1. Intramuscular administration of the probe resulted in a decrease of the T2 relaxation time of muscle from 33.4 + 2.5 msec to 20.3 + 2.2. SERS peaks were observed at 508, 629, 782, 844, 1080, 1108, 1135, and 1242 cm−1, consistent with the in silico results. Our studies illustrate for the first time the design and in vivo application of a contrast agent, whose component modalities include MRI and SERS. The value of this agent lies in its innately bimodal nature and its application in vivo for molecular imaging applications. PMID:21194236

  2. Magnetic Resonance Imaging (MRI) Evaluation for Anterior Disc Displacement of the Temporomandibular Joint

    PubMed Central

    Yang, Zhongjun; Wang, Mingguo; Ma, Yingwei; Lai, Qingguo; Tong, Dongdong; Zhang, Fenghe; Dong, Lili

    2017-01-01

    Background Magnetic resonance imaging (MRI) is the criterion standard imaging technique for visualization of the temporomandibular joint (TMJ) region, and is currently considered the optimum modality for comprehensive evaluation in patients with temporomandibular joint disorder (TMD). This study was aimed at finding the value of MRI in pre-clinical diagnosis of TMJ disc displacement. Material/Methods Patients primarily diagnosed as having anterior disc displacement by clinical symptoms and X-ray were selected in the present study. MRI was used to evaluate surrounding anatomical structures and position, as well as morphological and signal intensity change between patients and normal controls. Results Posterior band position was significantly different between the patient group and control group. At the maximum opened-mouth position, the location of disc intermediate zone returned to normal. At closed-mouth position, the thickness of anterior and middle, but not posterior, band increased. The motion range of the condyle in the anterior disc displacement without reduction (ADDWR) patient group was significantly less than the value in the anterior disc displacement with reduction (ADDR) patient group and the control group. Whether at closed-mouth position or maximum opened-mouth position, the exudate volume in the patient group was greater than in the normal group. Conclusions MRI can be successfully used to evaluate multiple morphological changes at different mouth positions of normal volunteers and patients. The disc-condyle relationship can serve as an important indicator in assessing anterior disc displacement, and can be used to distinguish disc displacement with or without reduction. PMID:28176754

  3. Categorization of Pathology Causing Low Back Pain using Magnetic Resonance Imaging (MRI)

    PubMed Central

    Nadhamuni, Kulasekaran; Karthikeyan, T.

    2015-01-01

    Background: Low backache is the most common ailment flooding the orthopaedic clinic. Most of the population at least once seek medical attention for low back ache. Magnetic Resonance Imaging (MRI) is a non invasive, commonly used diagnosing modality and accurate in diagnosing pathology causing low back ache. Aim: To classify and quantify the causes of low back pain referred to radiology department by MRI. Materials and Methods: Patients with back pain referred to radiology department were subjected to single MRI scan after ruling out any contraindications using the following sequences: T1W Turbo Spin Echo, T2W Turbo Spin Echo, Gradient-echo, Myelogram and short TI inversion recovery (STIR), in all imaging planes. Gadolinium enhanced T1W turbo spin echo sequence was used wherever necessary. Results: Data were analysed using Excel 2007, SPSS 14, Students t-test. Degenerative disc diseases were the commonest pathology followed by congenital and traumatic lesions. Neoplastic lesions were the least common. Commonest herniation type being the disc bulge (79%) followed by disc protrusion (15%), disc extrusion (6%) and disc sequestration (<1%). The posterolateral disc herniation as the commonest and foraminal the least. Sacralisation was the most common congenital spinal anomaly, followed by lumbar scoliosis and perineural cyst. There is no sex difference in disc protrusion but male preponderance in disc extrusion with subligmentous extrusion. Conclusion: MRI is useful in classifying the spinal lesions which again influences the treatment modality and clinical outcome. Degenerative disc disease is the single most common category which accounts for most the Low Back Ache for which a preventing strategy should be drafted. PMID:25738056

  4. Photoacoustic imaging of breast tumor vascularization: a comparison with MRI and histopathology

    NASA Astrophysics Data System (ADS)

    Heijblom, Michelle; Piras, Daniele; van den Engh, Frank M.; Klaase, Joost M.; Brinkhuis, Mariël.; Steenbergen, Wiendelt; Manohar, Srirang

    2013-06-01

    Breast cancer is the most common form of cancer and the leading cause of cancer death among females. Early diagnosis improves the survival chances for the disease and that is why there is an ongoing search for improved methods for visualizing breast cancer. One of the hallmarks of breast cancer is the increase in tumor vascularization that is associated with angiogenesis: a crucial factor for survival of malignancies. Photoacoustic imaging can visualize the malignancyassociated increased hemoglobin concentration with optical contrast and ultrasound resolution, without the use of ionizing radiation or contrast agents and is therefore theoretically an ideal method for breast imaging. Previous clinical studies using the Twente Photoacoustic Mammoscope (PAM), which works in forward mode using a single wavelength (1064 nm), showed that malignancies can indeed be identified in the photoacoustic imaging volume as high contrast areas. However, the specific appearance of the malignancies led to questions about the contrast mechanism in relation to tumor vascularization. In this study, the photoacoustic lesion appearance obtained with an updated version of PAM is compared with the lesion appearance on Magnetic Resonance Imaging (MRI), both in general (19 patients) and on an individual basis (7 patients). Further, in 3 patients an extended histopathology protocol is being performed in which malignancies are stained for vascularity using an endothelial antibody: CD31. The correspondence between PAM and MRI and between PAM and histopathology makes it likely that the high photoacoustic contrast at 1064 nm is indeed largely the consequence of the increased tumor vascularization.

  5. Identifying quantitative imaging features of posterior fossa syndrome in longitudinal MRI

    PubMed Central

    Spiteri, Michaela; Windridge, David; Avula, Shivaram; Kumar, Ram; Lewis, Emma

    2015-01-01

    Abstract. Up to 25% of children who undergo brain tumor resection surgery in the posterior fossa develop posterior fossa syndrome (PFS). This syndrome is characterized by mutism and disturbance in speech. Our hypothesis is that there is a correlation between PFS and the occurrence of hypertrophic olivary degeneration (HOD) in structures within the posterior fossa, known as the inferior olivary nuclei (ION). HOD is exhibited as an increase in size and intensity of the ION on an MR image. Longitudinal MRI datasets of 28 patients were acquired consisting of pre-, intra-, and postoperative scans. A semiautomated segmentation process was used to segment the ION on each MR image. A full set of imaging features describing the first- and second-order statistics and size of the ION were extracted for each image. Feature selection techniques were used to identify the most relevant features among the MRI features, demographics, and data based on neuroradiological assessment. A support vector machine was used to analyze the discriminative features selected by a generative k-nearest neighbor algorithm. The results indicate the presence of hyperintensity in the left ION as the most diagnostically relevant feature, providing a statistically significant improvement in the classification of patients (p=0.01) when using this feature alone. PMID:26835496

  6. Sodium and T1ρ MRI for molecular and diagnostic imaging of articular cartilage†

    PubMed Central

    Borthakur, Arijitt; Mellon, Eric; Niyogi, Sampreet; Witschey, Walter; Kneeland, J. Bruce; Reddy, Ravinder

    2010-01-01

    In this article, both sodium magnetic resonance (MR) and T1ρ relaxation mapping aimed at measuring molecular changes in cartilage for the diagnostic imaging of osteoarthritis are reviewed. First, an introduction to structure of cartilage, its degeneration in osteoarthritis (OA) and an outline of diagnostic imaging methods in quantifying molecular changes and early diagnostic aspects of cartilage degeneration are described. The sodium MRI section begins with a brief overview of the theory of sodium NMR of biological tissues and is followed by a section on multiple quantum filters that can be used to quantify both bi-exponential relaxation and residual quadrupolar interaction. Specifically, (i) the rationale behind the use of sodium MRI in quantifying proteoglycan (PG) changes, (ii) validation studies using biochemical assays, (iii) studies on human OA specimens, (iv) results on animal models and (v) clinical imaging protocols are reviewed. Results demonstrating the feasibility of quantifying PG in OA patients and comparison with that in healthy subjects are also presented. The section concludes with the discussion of advantages and potential issues with sodium MRI and the impact of new technological advancements (e.g. ultra-high field scanners and parallel imaging methods). In the theory section on T1ρ, a brief description of (i) principles of measuring T1ρ relaxation, (ii) pulse sequences for computing T1ρ relaxation maps, (iii) issues regarding radio frequency power deposition, (iv) mechanisms that contribute to T1ρ in biological tissues and (v) effects of exchange and dipolar interaction on T1ρ dispersion are discussed. Correlation of T1ρ relaxation rate with macromolecular content and biomechanical properties in cartilage specimens subjected to trypsin and cytokine-induced glycosaminoglycan depletion and validation against biochemical assay and histopathology are presented. Experimental T1ρ data from osteoarthritic specimens, animal models, healthy human

  7. Feasibility of magnetic resonance imaging (MRI) in obtaining nucleus pulposus (NP) water content with changing postures.

    PubMed

    Nazari, Jalil; Pope, Malcolm H; Graveling, Richard A

    2015-05-01

    Opportunities to evaluate spinal loading in vivo are limited and a large majority of studies on the mechanical functions of the spine have been in vitro cadaveric studies and/or models based on many assumptions that are difficult to validate. The purpose of this study was to investigate the feasibility of magnetic resonance imaging (MRI) in obtaining nucleus pulposus (NP) water content measurements with changing postures. MRI studies were conducted on 25 healthy males with no history of low back pain (age 20-38). The L1 to S1 intradiscal levels were imaged in supine, sitting and standing postures using an upright 0.6 Tesla magnet, where a set of H2O: D2O7 phantoms were mounted on the back of the subjects. A calibration curve, provided from these phantoms, was applied to the absolute proton density image, yielding a pixel-by-pixel map of the water content of the NP. The NP at all levels showed a highly significant water loss (p<0.001) in sitting and standing postures compared with the supine posture. A trend towards higher levels of water was observed at all levels in the standing posture relative to sitting postures, however statistically significant differences were found only at L4-L5 and L5-S1 levels. This study demonstrates that variations in water content of the NP in different postures are in agreement with those determined from published invasive disc pressure measurements. The result of study demonstrates the feasibility of using MRI to determine the water content of the NP with changing postures and to use these data to evaluate spinal loading in these postures. This measurement method of water content by quantitative MR imaging could become a powerful tool for both clinical and ergonomic applications. The proposed methodology does not require invasive pressure measurement techniques.

  8. Three-Dimensional Assessment of Temporomandibular Joint Using MRI-CBCT Image Registration

    PubMed Central

    Lagravere, Manuel; Boulanger, Pierre; Jaremko, Jacob L.; Major, Paul W.

    2017-01-01

    Purpose To introduce a new approach to reconstruct a 3D model of the TMJ using magnetic resonance imaging (MRI) and cone-beam computed tomography (CBCT) registered images, and to evaluate the intra-examiner reproducibility values of reconstructing the 3D models of the TMJ. Methods MRI and CBCT images of five patients (10 TMJs) were obtained. Multiple MRIs and CBCT images were registered using a mutual information based algorithm. The articular disc, condylar head and glenoid fossa were segmented at two different occasions, at least one-week apart, by one investigator, and 3D models were reconstructed. Differences between the segmentation at two occasions were automatically measured using the surface contours (Average Perpendicular Distance) and the volume overlap (Dice Similarity Index) of the 3D models. Descriptive analysis of the changes at 2 occasions, including means and standard deviation (SD) were reported to describe the intra-examiner reproducibility. Results The automatic segmentation of the condyle revealed maximum distance change of 1.9±0.93 mm, similarity index of 98% and root mean squared distance of 0.1±0.08 mm, and the glenoid fossa revealed maximum distance change of 2±0.52 mm, similarity index of 96% and root mean squared distance of 0.2±0.04 mm. The manual segmentation of the articular disc revealed maximum distance change of 3.6±0.32 mm, similarity index of 80% and root mean squared distance of 0.3±0.1 mm. Conclusion The MRI-CBCT registration provides a reliable tool to reconstruct 3D models of the TMJ’s soft and hard tissues, allows quantification of the articular disc morphology and position changes with associated differences of the condylar head and glenoid fossa, and facilitates measuring tissue changes over time. PMID:28095486

  9. Ultra-high magnetic resonance imaging (MRI): a potential examination for deep brain stimulation devices and the limitation study concerning MRI-related heating injury.

    PubMed

    Chen, Ying-Chuan; Li, Jun-Ju; Zhu, Guan-Yu; Shi, Lin; Yang, An-Chao; Jiang, Yin; Zhang, Xin; Zhang, Jian-Guo

    2017-03-01

    Nowadays, the patients with deep brain stimulation (DBS) devices are restricted to undertake 1.5T magnetic resonance imaging (MRI) according to the guideline. Nevertheless, we conducted an experiment to test pathological change near the leads in different field-strength MRI. Twenty-four male New Zealand rabbits were assigned to Group 1 (G1, n = 6, 7.0T, DBS), Group 2 (G2, n = 6, 3.0T, DBS), Group 3 (G3, n = 6, 1.5T, DBS), and Group 4 (G4, n = 6, 1.5T, paracentesis). DBS leads were implanted in G1, G2 and G3, targeting left nucleus ventralis posterior thalami. Paracentesis was performed in G4. 24 h after MRI scan, all animals were killed for examining pathological alternation (at different distance from lead) via transmission electron microscopy. Our results suggest that the severity of tissue injury correlates with the distance to electrode instead of field strength of MRI. Up to now, the reason for the restriction of MRI indicated no significantly different pathological change.

  10. Audiovisual biofeedback improves image quality and reduces scan time for respiratory-gated 3D MRI

    NASA Astrophysics Data System (ADS)

    Lee, D.; Greer, P. B.; Arm, J.; Keall, P.; Kim, T.

    2014-03-01

    The purpose of this study was to test the hypothesis that audiovisual (AV) biofeedback can improve image quality and reduce scan time for respiratory-gated 3D thoracic MRI. For five healthy human subjects respiratory motion guidance in MR scans was provided using an AV biofeedback system, utilizing real-time respiratory motion signals. To investigate the improvement of respiratory-gated 3D MR images between free breathing (FB) and AV biofeedback (AV), each subject underwent two imaging sessions. Respiratory-related motion artifacts and imaging time were qualitatively evaluated in addition to the reproducibility of external (abdominal) motion. In the results, 3D MR images in AV biofeedback showed more anatomic information such as a clear distinction of diaphragm, lung lobes and sharper organ boundaries. The scan time was reduced from 401±215 s in FB to 334±94 s in AV (p-value 0.36). The root mean square variation of the displacement and period of the abdominal motion was reduced from 0.4±0.22 cm and 2.8±2.5 s in FB to 0.1±0.15 cm and 0.9±1.3 s in AV (p-value of displacement <0.01 and p-value of period 0.12). This study demonstrated that audiovisual biofeedback improves image quality and reduces scan time for respiratory-gated 3D MRI. These results suggest that AV biofeedback has the potential to be a useful motion management tool in medical imaging and radiation therapy procedures.

  11. MRI Inner Ear Imaging and Tone Burst Electrocochleography in the Diagnosis of Ménière’s Disease

    PubMed Central

    Hornibrook, Jeremy; Flook, Edward; Greig, Sam; Babbage, Melissa; Goh, Tony; Coates, Mark; Care, Rachel; Bird, Philip

    2015-01-01

    Objective To compare the sensitivity of gadolinium MRI inner imaging with tone burst electrocochleography (EcochG) for diagnosing endolymphatic hydrops. Study Design A prospective study on patients who were to have an MRI scan to exclude retrocochlear pathology. Setting Tertiary care center. Patients One hundred and two patients: 57 patients with Possible, Probable, or Definite Ménière’s Disease, 25 with asymmetrical hearing loss, 18 with sudden sensorineural hearing loss, and 2 with unilateral tinnitus had additional MRI inner ear imaging and click and tone burst stimulus EcochG testing. Intervention Diagnostic. Main Outcome Measure To compare the sensitivity of the two techniques. Results In 30 patients with symptom-based Definite Ménière’s Disease, tone burst EcochG was positive in 25 (83%) and the click EcochG was positive in 9/30 (30%), and gadolinium MRI imaging diagnosed hydrops in 14 (47%). A positive result for either MRI imaging or tone burst EcochG was seen in 26 patients (87%). In 14 subjects with symptom-based Probable Ménière’s Disease, 10 (71%) had either a positive EcochG or MRI. In 13 with Possible Ménière’s Disease, four (31%) had a positive EcochG or MRI. Conclusion This study confirms the greatly enhanced diagnostic sensitivity of tone burst EcochG over click response in diagnosing endolymphatic hydrops in Ménière’s disease. Even though adequate MRI imaging was achieved in 90%, tone burst EcochG was a more sensitive test. PMID:25985318

  12. Simultaneous steering and imaging of magnetic particles using MRI toward delivery of therapeutics

    PubMed Central

    Felfoul, Ouajdi; Becker, Aaron T.; Fagogenis, Georgios; Dupont, Pierre E.

    2016-01-01

    Magnetic resonance navigation (MRN) offers the potential for real-time steering of drug particles and cells to targets throughout the body. In this technique, the magnetic gradients of an MRI scanner perform image-based steering of magnetically-labelled therapeutics through the vasculature and into tumours. A major challenge of current techniques for MRN is that they alternate between pulse sequences for particle imaging and propulsion. Since no propulsion occurs while imaging the particles, this results in a significant reduction in imaging frequency and propulsive force. We report a new approach in which an imaging sequence is designed to simultaneously image and propel particles. This sequence provides a tradeoff between maximum propulsive force and imaging frequency. In our reported example, the sequence can image at 27 Hz while still generating 95% of the force produced by a purely propulsive pulse sequence. We implemented our pulse sequence on a standard clinical scanner using millimetre-scale particles and demonstrated high-speed (74 mm/s) navigation of a multi-branched vascular network phantom. Our study suggests that the magnetic gradient magnitudes previously demonstrated to be sufficient for pure propulsion of micron-scale therapeutics in magnetic resonance targeting (MRT) could also be sufficient for real-time steering of these particles. PMID:27666666

  13. Simultaneous steering and imaging of magnetic particles using MRI toward delivery of therapeutics

    NASA Astrophysics Data System (ADS)

    Felfoul, Ouajdi; Becker, Aaron T.; Fagogenis, Georgios; Dupont, Pierre E.

    2016-09-01

    Magnetic resonance navigation (MRN) offers the potential for real-time steering of drug particles and cells to targets throughout the body. In this technique, the magnetic gradients of an MRI scanner perform image-based steering of magnetically-labelled therapeutics through the vasculature and into tumours. A major challenge of current techniques for MRN is that they alternate between pulse sequences for particle imaging and propulsion. Since no propulsion occurs while imaging the particles, this results in a significant reduction in imaging frequency and propulsive force. We report a new approach in which an imaging sequence is designed to simultaneously image and propel particles. This sequence provides a tradeoff between maximum propulsive force and imaging frequency. In our reported example, the sequence can image at 27 Hz while still generating 95% of the force produced by a purely propulsive pulse sequence. We implemented our pulse sequence on a standard clinical scanner using millimetre-scale particles and demonstrated high-speed (74 mm/s) navigation of a multi-branched vascular network phantom. Our study suggests that the magnetic gradient magnitudes previously demonstrated to be sufficient for pure propulsion of micron-scale therapeutics in magnetic resonance targeting (MRT) could also be sufficient for real-time steering of these particles.

  14. Cilengitide inhibits progression of experimental breast cancer bone metastases as imaged noninvasively using VCT, MRI and DCE-MRI in a longitudinal in vivo study.

    PubMed

    Bäuerle, Tobias; Komljenovic, Dorde; Merz, Maximilian; Berger, Martin R; Goodman, Simon L; Semmler, Wolfhard

    2011-05-15

    The aim of this study was to investigate the effect of inhibiting αvβ(3)/α(v) β(5) integrins by cilengitide in experimentally induced breast cancer bone metastases using noninvasive imaging techniques. For this purpose, nude rats bearing established breast cancer bone metastases were treated with cilengitide, a small molecule inhibitor of αvβ(3) and αvβ(5) integrins (75 mg/kg, five days per week; n = 12 rats) and compared to vehicle-treated control rats (n = 12). In a longitudinal study, conventional magnetic resonance imaging (MRI) and flat panel volumetric computed tomography were used to assess the volume of the soft tissue tumor and osteolysis, respectively, and dynamic contrast-enhanced (DCE-) MRI was performed to determine functional parameters of the tumor vasculature reflecting blood volume and blood vessel permeability. In rats treated with cilengitide, VCT and MRI showed that osteolytic lesions and the respective bone metastatic soft tissue tumors progressed more slowly than in vehicle-treated controls. DCE-MRI indicated a decrease in blood volume and an increase in vessel permeability and immunohistology revealed increased numbers of immature vessels in cilengitide-treated rats compared to vehicle controls. In conclusion, treatment of experimental breast cancer bone metastases with cilengitide resulted in pronounced antiresorptive and antitumor effects, suggesting that αvβ(3)/αvβ(5) inhibition may be a promising therapeutic approach for bone metastases.

  15. MRI Based Preterm White Matter Injury Classification: The Importance of Sequential Imaging in Determining Severity of Injury

    PubMed Central

    Martinez-Biarge, Miriam; Groenendaal, Floris; Kersbergen, Karina J.; Benders, Manon J. N. L.; Foti, Francesca; Cowan, Frances M.; de Vries, Linda S.

    2016-01-01

    Background The evolution of non-hemorrhagic white matter injury (WMI) based on sequential magnetic resonance imaging (MRI) has not been well studied. Our aim was to describe sequential MRI findings in preterm infants with non-hemorrhagic WMI and to develop an MRI classification system for preterm WMI based on these findings. Methods Eighty-two preterm infants (gestation ≤35 weeks) were retrospectively included. WMI was diagnosed and classified based on sequential cranial ultrasound (cUS) and confirmed on MRI. Results 138 MRIs were obtained at three time-points: early (<2 weeks; n = 32), mid (2–6 weeks; n = 30) and term equivalent age (TEA; n = 76). 63 infants (77%) had 2 MRIs during the neonatal period. WMI was non-cystic in 35 and cystic in 47 infants. In infants with cystic-WMI early MRI showed extensive restricted diffusion abnormalities, cysts were already present in 3 infants; mid MRI showed focal or extensive cysts, without acute diffusion changes. A significant reduction in the size and/or extent of the cysts was observed in 32% of the infants between early/mid and TEA MRI. In 4/9 infants previously seen focal cysts were no longer identified at TEA. All infants with cystic WMI showed ≥2 additional findings at TEA: significant reduction in WM volume, mild-moderate irregular ventriculomegaly, several areas of increased signal intensity on T1-weighted-images, abnormal myelination of the PLIC, small thalami. Conclusion In infants with extensive WM cysts at 2–6 weeks, cysts may be reduced in number or may even no longer be seen at TEA. A single MRI at TEA, without taking sequential cUS data and pre-TEA MRI findings into account, may underestimate the extent of WMI; based on these results we propose a new MRI classification for preterm non-hemorrhagic WMI. PMID:27257863

  16. Evaluating pH in the Extracellular Tumor Microenvironment Using CEST MRI and Other Imaging Methods

    PubMed Central

    Chen, Liu Qi; Pagel, Mark D.

    2016-01-01

    Tumor acidosis is a consequence of altered metabolism, which can lead to chemoresistance and can be a target of alkalinizing therapies. Noninvasive measurements of the extracellular pH (pHe) of the tumor microenvironment can improve diagnoses and treatment decisions. A variety of noninvasive imaging methods have been developed for measuring tumor pHe. This review provides a detailed description of the advantages and limitations of each method, providing many examples from previous research reports. A substantial emphasis is placed on methods that use MR spectroscopy and MR imaging, including recently developed methods that use chemical exchange saturation transfer MRI that combines some advantages of MR spectroscopy and imaging. Together, this review provides a comprehensive overview of methods for measuring tumor pHe, which may facilitate additional creative approaches in this research field. PMID:27761517

  17. Photouncaging nanoparticles for MRI and fluorescence imaging in vitro and in vivo.

    PubMed

    Shibu, Edakkattuparambil S; Ono, Kenji; Sugino, Sakiko; Nishioka, Ayami; Yasuda, Akikazu; Shigeri, Yasushi; Wakida, Shin-Ichi; Sawada, Makoto; Biju, Vasudevanpillai

    2013-11-26

    Multimodal and multifunctional nanomaterials are promising candidates for bioimaging and therapeutic applications in the nanomedicine settings. Here we report the preparation of photouncaging nanoparticles with fluorescence and magnetic modalities and evaluation of their potentials for in vitro and in vivo bioimaging. Photoactivation of such bimodal nanoparticles prepared using photouncaging ligands, CdSe/ZnS quantum dots, and super paramagnetic iron oxide nanoparticles results in the systematic uncaging of the particles, which is correlated with continuous changes in the absorption, mass and NMR spectra of the ligands. Fluorescence and magnetic components of the bimodal nanoparticles are characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), and elemental analyses using energy dispersive X-ray (EDX) spectroscopy and X-ray photoelectron spectroscopy (XPS). Bioconjugation of the nanoparticles with peptide hormones renders them with biocompatibility and efficient intracellular transport as seen in the fluorescence and MRI images of mouse melanoma cells (B16) or human lung epithelial adenocarcinoma cells (H1650). Biocompatibility of the nanoparticles is evaluated using MTT cytotoxicity assays, which show cell viability over 90%. Further, we combine MRI and NIR fluorescence imaging in C57BL/6 (B6) mice subcutaneously or intravenously injected with the photouncaging nanoparticles and follow the in vivo fate of the nanoparticles. Interestingly, the intravenously injected nanoparticles initially accumulate in the liver within 30 min post injection and subsequently clear by the renal excretion within 48 h as seen in the time-dependent MRI and fluorescence images of the liver, urinary bladder, and urine samples. Photouncaging ligands such as the ones reported in this article are promising candidates for not only the site-specific delivery of nanomaterials-based contrast agents and drugs but also the systematic uncaging and renal

  18. A case of catastrophic antiphospholipid syndrome: first report with advanced cardiac imaging using MRI.

    PubMed

    Rosenbaum, A N; Anavekar, N S; Ernste, F C; Mankad, S V; Le, R J; Manocha, K K; Barsness, G W

    2015-10-01

    This present case pertains to a 48-year-old woman with a history of antiphospholipid syndrome, who presented with progressive fatigue, generalized weakness, and orthopnea acutely. She had a prior diagnosis of antiphospholipid syndrome with recurrent deep vein thromboses (DVTs) and repeated demonstration of lupus anticoagulants. She presented in cardiogenic shock with markedly elevated troponin and global myocardial dysfunction on echocardiography, and cardiac catheterization revealed minimal disease. Cardiac magnetic resonance imaging was performed, which revealed findings of perfusion defects and microvascular obstruction, consistent with the pathophysiology of catastrophic antiphospholipid syndrome (CAPS). Diagnosis was made based on supportive imaging, including head magnetic resonance imaging (MRI) revealing multifocal, acute strokes; microvascular thrombosis in the dermis; and subacute renal infarctions. The patient was anticoagulated with intravenous unfractionated heparin and received high-dose methylprednisolone, plasmapheresis, intravenous immunoglobulin, and one dose each of rituximab and cyclophosphamide. She convalesced with eventual myocardial recovery after a complicated course. The diagnosis of CAPS relies on the presence of (1) antiphospholipid antibodies and (2) involvement of multiple organs in a microangiopathic thrombotic process with a close temporal association. The myocardium is frequently affected, and heart failure, either as the presenting symptom or cause of death, is common. Despite echocardiographic evidence of myocardial dysfunction in such patients, MRIs of CAPS have not previously been reported. This case highlights the utility in assessing the involvement of the myocardium by the microangiopathic process with MRI. Because the diagnosis of CAPS requires involvement in multiple organ systems, cardiac MRI is likely an underused tool that not only reaffirms the pathophysiology of CAPS, but could also clue clinicians in to the

  19. Effect of Imaging Parameter Thresholds on MRI Prediction of Neoadjuvant Chemotherapy Response in Breast Cancer Subtypes

    PubMed Central

    Jones, Ella F.; Newitt, David C.; Kornak, John; Wilmes, Lisa J.; Esserman, Laura J.; Hylton, Nola M.

    2016-01-01

    The purpose of this study is to evaluate the predictive performance of magnetic resonance imaging (MRI) markers in breast cancer patients by subtype. Sixty-four patients with locally advanced breast cancer undergoing neoadjuvant chemotherapy were enrolled in this study. Each patient received a dynamic contrast-enhanced (DCE-MRI) at baseline, after 1 cycle of chemotherapy and before surgery. Functional tumor volume (FTV), the imaging marker measured by DCE-MRI, was computed at various thresholds of percent enhancement (PEt) and signal-enhancement ratio (SERt). Final FTV before surgery and percent changes of FTVs at the early and final treatment time points were used to predict patients’ recurrence-free survival. The full cohort and each subtype defined by the status of hormone receptor and human epidermal growth factor receptor 2 (HR+/HER2-, HER2+, triple negative) were analyzed. Predictions were evaluated using the Cox proportional hazard model when PEt changed from 30% to 200% in steps of 10% and SERt changed from 0 to 2 in steps of 0.2. Predictions with high hazard ratios and low p-values were considered as strong. Different profiles of FTV as predictors for recurrence-free survival were observed in each breast cancer subtype and strong associations with survival were observed at different PEt/SERt combinations that resulted in different FTVs. Findings from this retrospective study suggest that the predictive performance of imaging markers based on FTV may be improved with enhancement thresholds being optimized separately for clinically-relevant subtypes defined by HR and HER2 receptor expression. PMID:26886725

  20. Controlling RNA Expression in Cancer Using Iron Oxide Nanoparticles Detectable by MRI and In Vivo Optical Imaging.

    PubMed

    Medarova, Zdravka; Balcioglu, Mustafa; Yigit, Mehmet V

    2016-01-01

    Herein, we describe a protocol for the preparation of iron oxide nanoparticle-based contrast agents and drug delivery vehicles for noninvasive cancer imaging and therapy. In the first part of the chapter we describe the details of the contrast agent synthesis, functionalization, and characterization. In the second part we describe the methods for tumor imaging using the synthesized particles with noninvasive T2-weighted magnetic resonance imaging (MRI) and in vivo near infrared optical imaging.

  1. Fat Imaging via Magnetic Resonance Imaging (MRI) in Young Children (Ages 1-4 Years) without Sedation

    PubMed Central

    Shearrer, Grace E.; House, Benjamin T.; Gallas, Michelle C.; Luci, Jeffrey J.; Davis, Jaimie N.

    2016-01-01

    Introduction This pilot study developed techniques to perform Magnetic Resonance Imaging (MRI) of specific fat deposition in 18 children (age 18 months to 4 years). Methods The children engaged in a series of practice tests to become acclimated to the scanner noises, reduce claustrophobia, and rehearse holding still for a set time. The practice tests assessed if the child could remain still for two minutes while watching a video, first while lying on a blanket, second, on the blanket with headphones, and third, in the mock scanner. The children who passed the three practice tests were then scanned with a 3T Siemens Skyra magnet. Abdominal fat distribution (region of interest (ROI) from the top of the ileac crest to the bottom of the ribcage) volume was measured using 2-point DIXON technique. This region was chosen to give an indication of the body composition around the liver. Results Twelve out of eighteen participants successfully completed the actual MRI scan. Chi-squared test showed no significant difference between male and female pass-fail rates. The median age of completed scans was 36 months, whereas the median age for children unable to complete a scan was 28 months. The average total trunk fat was 240.9±85.2mL and the average total VAT was 37.7±25.9mLand liver fat was not quantifiable due to physiological motion. Several strategies (modeling, videos, and incentives) were identified to improve pediatric imaging in different age ranges. Conclusion Using an age-specific and tailored protocol, we were able to successfully use MRI for fat imaging in a majority of young children. Development of such protocols enables researchers to better understand the etiology of fat deposition in young children, which can be used to aid in the prevention and treatment of adiposity. PMID:26901881

  2. Imaging features in conventional MRI, spectroscopy and diffusion weighted images of hereditary diffuse leukoencephalopathy with axonal spheroids (HDLS).

    PubMed

    Bender, Benjamin; Klose, Uwe; Lindig, Tobias; Biskup, Saskia; Nägele, Thomas; Schöls, Ludger; Karle, Kathrin N

    2014-12-01

    Hereditary diffuse leukoencephalopathy with axonal spheroids (HDLS) is a rare autosomal dominant disease caused by mutations within the colony stimulating factor 1 receptor (CSF1R) gene. While a small number of reports on imaging findings in routine MRI exist, reported imaging findings in DWI and spectroscopy are scarce, and limited to not genetically proven case reports. We assessed MRI including DWI and MR spectroscopy in six patients with HDLS and two asymptomatic mutation carriers. A total of 13 MRIs were evaluated and a score of the white-matter lesion (WML) load was calculated. The course of MR abnormalities was followed for 6-19 months in four patients and 95 months in one carrier. MRI revealed widespread white-matter lesions of patchy or confluent pattern especially in the frontal and occipital lobe. The pyramidal tract was less affected than the surrounding tissue in all symptomatic patients on conventional T2WI. Three of four cases with DWI showed small dots of diffusion restriction within WML. Spectroscopy showed increased levels of mIns, Cho and lactate while NAA was decreased. Asymptomatic mutation carriers had, for the age of the patients, unusually pronounced unspecific WMLs. No diffusion restriction or alterations in metabolite levels could be detected in asymptomatic mutation carriers. Microbleeds were not found in any patient. Diffusion restriction seems to be a typical imaging pattern visible in patients with active disease progression in HDLS. Spectroscopic findings and the absence of microbleeds differ clearly from reported findings in CADASIL and subcortical arteriosclerotic encephalopathy. While the distribution and character of WMLs in asymptomatic cases remain unspecific they are likely to represent subclinical markers of HDLS.

  3. Microstructure Imaging of Crossing (MIX) White Matter Fibers from diffusion MRI

    PubMed Central

    Farooq, Hamza; Xu, Junqian; Nam, Jung Who; Keefe, Daniel F.; Yacoub, Essa; Georgiou, Tryphon; Lenglet, Christophe

    2016-01-01

    Diffusion MRI (dMRI) reveals microstructural features of the brain white matter by quantifying the anisotropic diffusion of water molecules within axonal bundles. Yet, identifying features such as axonal orientation dispersion, density, diameter, etc., in complex white matter fiber configurations (e.g. crossings) has proved challenging. Besides optimized data acquisition and advanced biophysical models, computational procedures to fit such models to the data are critical. However, these procedures have been largely overlooked by the dMRI microstructure community and new, more versatile, approaches are needed to solve complex biophysical model fitting problems. Existing methods are limited to models assuming single fiber orientation, relevant to limited brain areas like the corpus callosum, or multiple orientations but without the ability to extract detailed microstructural features. Here, we introduce a new and versatile optimization technique (MIX), which enables microstructure imaging of crossing white matter fibers. We provide a MATLAB implementation of MIX, and demonstrate its applicability to general microstructure models in fiber crossings using synthetic as well as ex-vivo and in-vivo brain data. PMID:27982056

  4. A robust independent component analysis (ICA) model for functional magnetic resonance imaging (fMRI) data

    NASA Astrophysics Data System (ADS)

    Ao, Jingqi; Mitra, Sunanda; Liu, Zheng; Nutter, Brian

    2011-03-01

    The coupling of carefully designed experiments with proper analysis of functional magnetic resonance imaging (fMRI) data provides us with a powerful as well as noninvasive tool to help us understand cognitive processes associated with specific brain regions and hence could be used to detect abnormalities induced by a diseased state. The hypothesisdriven General Linear Model (GLM) and the data-driven Independent Component Analysis (ICA) model are the two most commonly used models for fMRI data analysis. A hybrid ICA-GLM model combines the two models to take advantages of benefits from both models to achieve more accurate mapping of the stimulus-induced activated brain regions. We propose a modified hybrid ICA-GLM model with probabilistic ICA that includes a noise model. In this modified hybrid model, a probabilistic principle component analysis (PPCA)-based component number estimation is used in the ICA stage to extract the intrinsic number of original time courses. In addition, frequency matching is introduced into the time course selection stage, along with temporal correlation, F-test based model fitting estimation, and time course combination, to produce a more accurate design matrix for GLM. A standard fMRI dataset is used to compare the results of applying GLM and the proposed hybrid ICA-GLM in generating activation maps.

  5. Computational imaging reveals shape differences between normal and malignant prostates on MRI

    PubMed Central

    Rusu, Mirabela; Purysko, Andrei S.; Verma, Sadhna; Kiechle, Jonathan; Gollamudi, Jay; Ghose, Soumya; Herrmann, Karin; Gulani, Vikas; Paspulati, Raj; Ponsky, Lee; Böhm, Maret; Haynes, Anne-Maree; Moses, Daniel; Shnier, Ron; Delprado, Warick; Thompson, James; Stricker, Phillip; Madabhushi, Anant

    2017-01-01

    We seek to characterize differences in the shape of the prostate and the central gland (combined central and transitional zones) between men with biopsy confirmed prostate cancer and men who were identified as not having prostate cancer either on account of a negative biopsy or had pelvic imaging done for a non-prostate malignancy. T2w MRI from 70 men were acquired at three institutions. The cancer positive group (PCa+) comprised 35 biopsy positive (Bx+) subjects from three institutions (Gleason scores: 6–9, Stage: T1–T3). The negative group (PCa−) combined 24 biopsy negative (Bx−) from two institutions and 11 subjects diagnosed with rectal cancer but with no clinical or MRI indications of prostate cancer (Cl−). The boundaries of the prostate and central gland were delineated on T2w MRI by two expert raters and were used to construct statistical shape atlases for the PCa+, Bx− and Cl− prostates. An atlas comparison was performed via per-voxel statistical tests to localize shape differences (significance assessed at p < 0.05). The atlas comparison revealed central gland hypertrophy in the Bx− subpopulation, resulting in significant volume and posterior side shape differences relative to PCa+ group. Significant differences in the corresponding prostate shapes were noted at the apex when comparing the Cl− and PCa+ prostates. PMID:28145532

  6. Targeted Multifunctional Nanoparticles cure and image Brain Tumors: Selective MRI Contrast Enhancement and Photodynamic Therapy

    NASA Astrophysics Data System (ADS)

    Kopelman, Raoul

    2008-03-01

    Aimed at targeted therapy and imaging of brain tumors, our approach uses targeted, multi-functional nano-particles (NP). A typical nano-particle contains a biologically inert, non-toxic matrix, biodegradable and bio-eliminable over a long time period. It also contains active components, such as fluorescent chemical indicators, photo-sensitizers, MRI contrast enhancement agents and optical imaging dyes. In addition, its surface contains molecular targeting units, e.g. peptides or antibodies, as well as a cloaking agent, to prevent uptake by the immune system, i.e. enabling control of the plasma residence time. These dynamic nano-platforms (DNP) contain contrast enhancement agents for the imaging (MRI, optical, photo-acoustic) of targeted locations, i.e. tumors. Added to this are targeted therapy agents, such as photosensitizers for photodynamic therapy (PDT). A simple protocol, for rats implanted with human brain cancer, consists of tail injection with DNPs, followed by 5 min red light illumination of the tumor region. It resulted in excellent cure statistics for 9L glioblastoma.

  7. 1.5 Tesla MRI-Conditional 12-lead ECG for MR Imaging and Intra-MR Intervention

    PubMed Central

    Tse, Zion Tsz Ho; Dumoulin, Charles L.; Clifford, Gari D.; Schweitzer, Jeff; Qin, Lei; Oster, Julien; Jerosch-Herold, Michael; Kwong, Raymond Y.; Michaud, Gregory; Stevenson, William G.; Schmidt, Ehud J.

    2013-01-01

    Propose High-fidelity 12-lead Electrocardiogram (ECG) is important for physiological monitoring of patients during MR-guided intervention and cardiac MR imaging. Issues in obtaining non-corrupted ECGs inside MRI include a superimposed Magneto-Hydro-Dynamic (MHD) voltage, gradient-switching induced-voltages, and radiofrequency (RF) heating. These problems increase with magnetic field. We intended to develop and clinically validate a 1.5T MRI-conditional 12-lead ECG system. Methods The system was constructed, including transmission-lines to reduce radio-frequency induction, and switching-circuits to remove induced voltages. Adaptive filters, trained by 12-lead measurements outside MRI and in two orientations inside MRI, were used to remove MHD. The system was tested on ten (one exercising) volunteers and four arrhythmia patients. Results Switching circuits removed most imaging-induced voltages (residual noise <3% of the R-wave). MHD removal provided intra-MRI ECGs that varied by <3.8% from those outside the MRI, preserving the true ST segment. In premature-ventricular-contraction (PVC) patients, clean ECGs separated PVC and sinus-rhythm beats. Measured heating was <1.5 C0. The system reliably acquired multiphase (SSFP) wall-motion-cine and phase-contrast-cine scans, including in subjects where 4-lead gating failed. The system required a minimum TR of 4ms to allow robust ECG processing. Conclusion High-fidelity intra-MRI 12-lead ECG is possible. PMID:23580148

  8. High-Relaxivity MRI Contrast Agents: Where Coordination Chemistry Meets Medical Imaging

    SciTech Connect

    Werner, Eric J.; Datta, Ankona; Jocher, Christoph J.; Raymond, Kenneth N.

    2008-01-15

    The desire to improve and expand the scope of clinical magnetic resonance imaging (MRI) has prompted the search for contrast agents of higher efficiency. The development of better agents requires consideration of the fundamental coordination chemistry of the gadolinium(III) ion and the parameters that affect its efficacy as a proton relaxation agent. In optimizing each parameter, other practical issues such as solubility and in vivo toxicity must also be addressed, making the attainment of safe, high-relaxivity agents a challenging goal. Here we present recent advances in the field, with an emphasis on the hydroxypyridinone family of Gd{sup III} chelates.

  9. Genetic engineered molecular imaging probes for applications in cell therapy: emphasis on MRI approach

    PubMed Central

    Cho, In K; Wang, Silun; Mao, Hui; Chan, Anthony WS

    2016-01-01

    Recent advances in stem cell-based regenerative medicine, cell replacement therapy, and genome editing technologies (i.e. CRISPR-Cas 9) have sparked great interest in in vivo cell monitoring. Molecular imaging promises a unique approach to noninvasively monitor cellular and molecular phenomena, including cell survival, migration, proliferation, and even differentiation at the whole organismal level. Several imaging modalities and strategies have been explored for monitoring cell grafts in vivo. We begin this review with an introduction describing the progress in stem cell technology, with a perspective toward cell replacement therapy. The importance of molecular imaging in reporting and assessing the status of cell grafts and their relation to the local microenvironment is highlighted since the current knowledge gap is one of the major obstacles in clinical translation of stem cell therapy. Based on currently available imaging techniques, we provide a brief discussion on the pros and cons of each imaging modality used for monitoring cell grafts with particular emphasis on magnetic resonance imaging (MRI) and the reporter gene approach. Finally, we conclude with a comprehensive discussion of future directions of applying molecular imaging in regenerative medicine to emphasize further the importance of correlating cell graft conditions and clinical outcomes to advance regenerative medicine. PMID:27766183

  10. [MRI image reconstruction using polar-coordinates conversion of k-space data].

    PubMed

    Tachibana, Atsushi; Hashimoto, Takeyuki; Sakaguchi, Kazuya; Obata, Takayuki; Shinohara, Hiroyuki

    2012-01-01

    In this study, we proposed the new reconstruction techniques for magnetic resonance imaging (MRI) using filtered back projection (FBP) or simultaneous reconstruction technique (SIRT). We converted the k-space which was acquired by conventional phase-encoding schemes from Cartesian coordinates to polar coordinates and created the projection. The linear interpolation and the sinc interpolation were used in the conversion. The accuracy of the reconstructed image using projection was evaluated by the relative error in comparison with the standard image which was reconstructed by the two-dimensional Fourier transform (2DFT) with conventional Cartesian k-space. The relative error reconstructed both FBP and SIRT from projection with sinc interpolation is 0.013. The maximum value of standard image is 1.501451, FBP is 1.47921, and SIRT with iteration 100 is 1.44858 and with iteration 200 is 1.579442. The minimum value of both the standard image and the others is about 0. Visually, there is no margin between the standard image and the reconstructed image from projection with FBP or SIRT.

  11. The role of magnetic resonance imaging (MRI) in focal therapy for prostate cancer: recommendations from a consensus panel

    PubMed Central

    Muller, Berrend G.; Fütterer, Jurgen J.; Gupta, Rajan T.; Katz, Aaron; Kirkham, Alexander; Kurhanewicz, John; Moul, Judd W.; Pinto, Peter A.; Rastinehad, Ardeshir R.; Robertson, Cary; de la Rosette, Jean; Sanchez-Salas, Rafael; Jones, J. Stephen; Ukimura, Osamu; Verma, Sadhna; Wijkstra, Hessel; Marberger, Michael

    2014-01-01

    Objective To establish a consensus on the utility of multiparametric magnetic resonance imaging (mpMRI) to identify patients for focal therapy. Methods Urological surgeons, radiologists, and basic researchers, from Europe and North America participated in a consensus meeting about the use of mpMRI in focal therapy of prostate cancer.The consensus process was face-to-face and specific clinical issues were raised and discussed with agreement sought when possible. All participants are listed among the authors.Topics specifically did not include staging of prostate cancer, but rather identifying the optimal requirements for performing MRI, and the current status of optimally performed mpMRI to (i) determine focality of prostate cancer (e.g. localising small target lesions of ≥0.5 mL), (ii) to monitor and assess the outcome of focal ablation therapies, and (iii) to identify the diagnostic advantages of new MRI methods.In addition, the need for transperineal template saturation biopsies in selecting patients for focal therapy was discussed, if a high quality mpMRI is available. In other words, can mpMRI replace the role of transperineal saturation biopsies in patient selection for focal therapy? Results Consensus was reached on most key aspects of the meeting; however, on definition of the optimal requirements for mpMRI, there was one dissenting voice.mpMRI is the optimum approach to achieve the objectives needed for focal therapy, if made on a high quality machine (3T with/without endorectal coil or 1.5T with endorectal coil) and judged by an experienced radiologist.Structured and standardised reporting of prostate MRI is paramount.State of the art mpMRI is capable of localising small tumours for focal therapy.State of the art mpMRI is the technique of choice for follow-up of focal ablation. Conclusions The present evidence for MRI in focal therapy is limited.mpMRI is not accurate enough to consistently grade tumour aggressiveness.Template-guided saturation biopsies

  12. Methods of MRI-Based Structural Imaging in the Aging Monkey

    PubMed Central

    Makris, N.; Kennedy, D. N.; Boriel, D.L.; Rosene, D. L.

    2013-01-01

    Rhesus monkeys, whose typical lifespan can be as long as 30 years in the presence of veterinary care, undergo a cognitive decline as a function of age. While cortical neurons are largely preserved in the cerebral cortex, including primary motor and visual cortex as well as prefrontal association cortex there is marked breakdown of axonal myelin and an overall reduction in white matter predominantly in the frontal and temporal lobes. Whether the myelin breakdown is diffuse or specific to individual white matter fiber pathways is important to be known with certainty. To this end the delineation and quantification of specific frontotemporal fiber pathways within the frontal and temporal lobes is essential to determine which structures are altered and the extent to which these alterations correlate with behavioral findings. The capability of studying the living brain non-invasively with MRI opens up a new window in structural-functional and anatomic-clinical relationships allowing the integration of information derived from different scanning modalities in the same subject. For instance, for any particular voxel in the cerebrum we can obtain structural T1-, diffusion- and magnetization transfer-magnetic resonance imaging (MRI) based information. Moreover, it is thus possible to follow any observed changes longitudinally over time. These acquisitions of multidimensional data in the same individual within the same MRI experimental setting would enable the creation of a data base of integrated structural MRI-behavioral correlations for normal aging monkeys to elucidate the underlying neurobiological mechanisms of functional senescence in the aging non-human primate. PMID:19577648

  13. Diagnostic Performance of Dual-Energy CT Stress Myocardial Perfusion Imaging: Direct Comparison With Cardiovascular MRI

    PubMed Central

    Ko, Sung Min; Song, Meong Gun; Chee, Hyun Kun; Hwang, Hweung Kon; Feuchtner, Gudrun Maria; Min, James K.

    2014-01-01

    OBJECTIVE The purpose of this study was to assess the diagnostic performance of stress perfusion dual-energy CT (DECT) and its incremental value when used with coronary CT angiography (CTA) for identifying hemodynamically significant coronary artery disease. SUBJECTS AND METHODS One hundred patients with suspected or known coronary artery disease without chronic myocardial infarction detected with coronary CTA underwent stress perfusion DECT, stress cardiovascular perfusion MRI, and invasive coronary angiography (ICA). Stress perfusion DECT and cardiovascular stress perfusion MR images were used for detecting perfusion defects. Coronary CTA and ICA were evaluated in the detection of ≥ 50% coronary stenosis. The diagnostic performance of coronary CTA for detecting hemodynamically significant stenosis was assessed before and after stress perfusion DECT on a pervessel basis with ICA and cardiovascular stress perfusion MRI as the reference standard. RESULTS The performance of stress perfusion DECT compared with cardiovascular stress perfusion MRI on a per-vessel basis in the detection of perfusion defects was sensitivity, 89%; specificity, 74%; positive predictive value, 73%; negative predictive value, 90%. Per segment, these values were sensitivity, 76%; specificity, 80%; positive predictive value, 63%; and negative predictive value, 88%. Compared with ICA and cardiovascular stress perfusion MRI per vessel territory the sensitivity, specificity, positive predictive value, and negative predictive value of coronary CTA were 95%, 61%, 61%, and 95%. The values for stress perfusion DECT were 92%, 72%, 68%, and 94%. The values for coronary CTA and stress perfusion DECT were 88%, 79%, 73%, and 91%. The ROC AUC increased from 0.78 to 0.84 (p = 0.02) with the use of coronary CTA and stress perfusion DECT compared with coronary CTA alone. CONCLUSION Stress perfusion DECT plays a complementary role in enhancing the accuracy of coronary CTA for identifying hemodynamically

  14. Incidental Memory Encoding Assessed with Signal Detection Theory and Functional Magnetic Resonance Imaging (fMRI)

    PubMed Central

    Clemens, Benjamin; Regenbogen, Christina; Koch, Kathrin; Backes, Volker; Romanczuk-Seiferth, Nina; Pauly, Katharina; Shah, N. Jon; Schneider, Frank; Habel, Ute; Kellermann, Thilo

    2015-01-01

    In functional magnetic resonance imaging (fMRI) studies that apply a “subsequent memory” approach, successful encoding is indicated by increased fMRI activity during the encoding phase for hits vs. misses, in areas underlying memory encoding such as the hippocampal formation. Signal-detection theory (SDT) can be used to analyze memory-related fMRI activity as a function of the participant’s memory trace strength (d′). The goal of the present study was to use SDT to examine the relationship between fMRI activity during incidental encoding and participants’ recognition performance. To implement a new approach, post-experimental group assignment into High- or Low Performers (HP or LP) was based on 29 healthy participants’ recognition performance, assessed with SDT. The analyses focused on the interaction between the factors group (HP vs. LP) and recognition performance (hits vs. misses). A whole-brain analysis revealed increased activation for HP vs. LP during incidental encoding for remembered vs. forgotten items (hits > misses) in the insula/temporo-parietal junction (TPJ) and the fusiform gyrus (FFG). Parameter estimates in these regions exhibited a significant positive correlation with d′. As these brain regions are highly relevant for salience detection (insula), stimulus-driven attention (TPJ), and content-specific processing of mnemonic stimuli (FFG), we suggest that HPs’ elevated memory performance was associated with enhanced attentional and content-specific sensory processing during the encoding phase. We provide first correlative evidence that encoding-related activity in content-specific sensory areas and content-independent attention and salience detection areas influences memory performance in a task with incidental encoding of facial stimuli. Based on our findings, we discuss whether the aforementioned group differences in brain activity during incidental encoding might constitute the basis of general differences in memory performance

  15. Integrated contour detection and pose estimation for fluoroscopic analysis of knee implants.

    PubMed

    Prins, A H; Kaptein, B L; Stoel, B C; Nelissen, R G H H; Reiber, J H C; Valstar, E R

    2011-08-01

    With fluoroscopic analysis of knee implant kinematics the implant contour must be detected in each image frame, followed by estimation of the implant pose. With a large number of possibly low-quality images, the contour detection is a time-consuming bottleneck. The present paper proposes an automated contour detection method, which is integrated in the pose estimation. In a phantom experiment the automated method was compared with a standard method, which uses manual selection of correct contour parts. Both methods demonstrated comparable precision, with a minor difference in the Y-position (0.08 mm versus 0.06 mm). The precision of each method was so small (below 0.2 mm and 0.3 degrees) that both are sufficiently accurate for clinical research purposes. The efficiency of both methods was assessed on six clinical datasets. With the automated method the observer spent 1.5 min per image, significantly less than 3.9 min with the standard method. A Bland-Altman analysis between the methods demonstrated no discernible trends in the relative femoral poses. The threefold increase in efficiency demonstrates that a pose estimation approach with integrated contour detection is more intuitive than a standard method. It eliminates most of the manual work in fluoroscopic analysis, with sufficient precision for clinical research purposes.

  16. Improving accuracy of markerless tracking of lung tumours in fluoroscopic video by incorporating diaphragm motion

    NASA Astrophysics Data System (ADS)

    Schwarz, M.; Teske, H.; Stoll, M.; Bendl, Rolf

    2014-03-01

    Purpose: Conformal radiation of moving tumours is a challenging task in radiotherapy. Tumour motion induced by respiration can be visualized in fluoroscopic images recorded during patients breathing. Markerless methods making use of registration techniques can be used to estimate tumour motion. However, registration methods might fail when the tumour is hidden by ribs. Using motion of anatomical surrogates, like the diaphragm, is promising to model tumour motion. Methods: A sequence of 116 fluoroscopic images was analyzed and the tumour positions were manually defined by three experts. A block matching (BM) technique is used to calculate the displacement vector relatively to a selected reference image of the first breathing cycle. An enhanced method was developed: Positions, when the tumour is not located behind a rib, are taken as valid estimations of the tumour position. Furthermore, these valid estimations are used to establish a linear model of tumour position and diaphragm motion. For invalid estimations the calculated tumour positions are not taken into consideration, and instead the model is used to determine tumour motion. Results: Enhancing BM with a model of tumour motion from diaphragm motion improves the tracking accuracy when the tumour moves behind a rib. The error (mean ± SD) in longitudinal dimension was 2.0 ± 1.5mm using only BM and 1.0 ± 1.1mm when the enhanced approach was used. Conclusion: The enhanced tracking technique is capable to improve tracking accuracy compared to BM in the case that the tumour is occluded by ribs.

  17. Spatially resolved quantification of gadolinium(III)-based magnetic resonance agents in tissue by MALDI imaging mass spectrometry after in vivo MRI.

    PubMed

    Aichler, Michaela; Huber, Katharina; Schilling, Franz; Lohöfer, Fabian; Kosanke, Katja; Meier, Reinhard; Rummeny, Ernst J; Walch, Axel; Wildgruber, Moritz

    2015-03-27

    Gadolinium(III)-based contrast agents improve the sensitivity and specificity of magnetic resonance imaging (MRI), especially when targeted contrast agents are applied. Because of nonlinear correlation between the contrast agent concentration in tissue and the MRI signal obtained in vivo, quantification of certain biological or pathophysiological processes by MRI remains a challenge. Up to now, no technology has been able to provide a spatially resolved quantification of MRI agents directly within the tissue, which would allow a more precise verification of in vivo imaging results. MALDI imaging mass spectrometry for spatially resolved in situ quantification of gadolinium(III) agents, in correlation to in vivo MRI, were evaluated. Enhanced kinetics of Gadofluorine M were determined dynamically over time in a mouse model of myocardial infarction. MALDI imaging was able to corroborate the in vivo imaging MRI signals and enabled in situ quantification of the gadolinium probe with high spatial resolution.

  18. Silica micro/nanospheres for theranostics: from bimodal MRI and fluorescent imaging probes to cancer therapy

    PubMed Central

    Walia, Shanka

    2015-01-01

    Summary Nano-theranostics offer remarkable potential for future biomedical technology with simultaneous applications for diagnosis and therapy of disease sites. Through smart and careful chemical modifications of the nanoparticle surface, these can be converted to multifunctional tiny objects which in turn can be used as vehicle for delivering multimodal imaging agents and therapeutic material to specific target sites in vivo. In this sense, bimodal imaging probes that simultaneously enable magnetic resonance imaging and fluorescence imaging have gained tremendous attention because disease sites can be characterized quick and precisely through synergistic multimodal imaging. But such hybrid nanocomposite materials have limitations such as low chemical stability (magnetic component) and harsh cytotoxic effects (fluorescent component) and, hence, require a biocompatible protecting agent. Silica micro/nanospheres have shown promise as protecting agent due to the high stability and low toxicity. This review will cover a full description of MRI-active and fluorescent multifunctional silica micro/nanospheres including the design of the probe, different characterization methods and their application in imaging and treatment in cancer. PMID:25821696

  19. WE-G-18C-08: Real Time Tumor Imaging Using a Novel Dynamic Keyhole MRI Reconstruction Technique

    SciTech Connect

    Lee, D; Pollock, S; Whelan, B; Keall, P; Greer, P; Kim, T

    2014-06-15

    Purpose: To test the hypothesis that the novel Dynamic Keyhole MRI reconstruction technique can accelerate image acquisition whilst maintaining high image quality for lung cancer patients. Methods: 18 MRI datasets from 5 lung cancer patients were acquired using a 3T MRI scanner. These datasets were retrospectively reconstructed using (A) The novel Dynamic Keyhole technique, (B) The conventional keyhole technique and (C) the conventional zero filling technique. The dynamic keyhole technique in MRI refers to techniques in which previously acquired k-space data is used to supplement under sampled data obtained in real time. The novel Dynamic Keyhole technique utilizes a previously acquired a library of kspace datasets in conjunction with central k-space datasets acquired in realtime. A simultaneously acquired respiratory signal is utilized to sort, match and combine the two k-space streams with respect to respiratory displacement. Reconstruction performance was quantified by (1) comparing the keyhole size (which corresponds to imaging speed) required to achieve the same image quality, and (2) maintaining a constant keyhole size across the three reconstruction methods to compare the resulting image quality to the ground truth image. Results: (1) The dynamic keyhole method required a mean keyhole size which was 48% smaller than the conventional keyhole technique and 60% smaller than the zero filling technique to achieve the same image quality. This directly corresponds to faster imaging. (2) When a constant keyhole size was utilized, the Dynamic Keyhole technique resulted in the smallest difference of the tumor region compared to the ground truth. Conclusion: The dynamic keyhole is a simple and adaptable technique for clinical applications requiring real-time imaging and tumor monitoring such as MRI guided radiotherapy. Based on the results from this study, the dynamic keyhole method could increase the imaging frequency by a factor of five compared with full k

  20. Predictive equations for central obesity via anthropometrics, stereovision imaging, and MRI in adults

    PubMed Central

    Lee, Jane J; Freeland-Graves, Jeanne H; Pepper, M Reese; Yao, Ming; Xu, Bugao

    2013-01-01

    Objective Abdominal visceral adiposity is related to risks for insulin resistance and metabolic perturbations. Magnetic resonance imaging (MRI) and computed tomography are advanced instruments that quantify abdominal adiposity; yet field use is constrained by their bulkiness and costliness. The purpose of this study is to develop prediction equations for total abdominal, subcutaneous, and visceral adiposity via anthropometrics, stereovision body imaging (SBI), and MRI. Design and Methods Participants (67 men and 55 women) were measured for anthropometrics, and abdominal adiposity volumes evaluated by MRI umbilicus scans. Body circumferences and central obesity were obtained via SBI. Prediction models were developed via multiple linear regression analysis, utilizing body measurements and demographics as independent predictors, and abdominal adiposity as a dependent variable. Cross-validation was performed by the data-splitting method. Results The final total abdominal adiposity prediction equation was –470.28+7.10waist circumference–91.01gender+5.74sagittal diameter (R²=89.9%); subcutaneous adiposity was –172.37+8.57waist circumference–62.65gender–450.16stereovision waist-to-hip ratio (R²=90.4%); and visceral adiposity was –96.76+11.48central obesity depth–5.09 central obesity width+204.74stereovision waist-to-hip ratio–18.59gender (R²=71.7%). R² significantly improved for predicting visceral fat when SBI variables were included, but not for total abdominal or subcutaneous adiposity. Conclusions SBI is effective for predicting visceral adiposity and the prediction equations derived from SBI measurements can assess obesity. PMID:23613161

  1. Predicting axillary lymph node metastasis from kinetic statistics of DCE-MRI breast images

    NASA Astrophysics Data System (ADS)

    Ashraf, Ahmed B.; Lin, Lilie; Gavenonis, Sara C.; Mies, Carolyn; Xanthopoulos, Eric; Kontos, Despina

    2012-03-01

    The presence of axillary lymph node metastases is the most important prognostic factor in breast cancer and can influence the selection of adjuvant therapy, both chemotherapy and radiotherapy. In this work we present a set of kinetic statistics derived from DCE-MRI for predicting axillary node status. Breast DCE-MRI images from 69 women with known nodal status were analyzed retrospectively under HIPAA and IRB approval. Axillary lymph nodes were positive in 12 patients while 57 patients had no axillary lymph node involvement. Kinetic curves for each pixel were computed and a pixel-wise map of time-to-peak (TTP) was obtained. Pixels were first partitioned according to the similarity of their kinetic behavior, based on TTP values. For every kinetic curve, the following pixel-wise features were computed: peak enhancement (PE), wash-in-slope (WIS), wash-out-slope (WOS). Partition-wise statistics for every feature map were calculated, resulting in a total of 21 kinetic statistic features. ANOVA analysis was done to select features that differ significantly between node positive and node negative women. Using the computed kinetic statistic features a leave-one-out SVM classifier was learned that performs with AUC=0.77 under the ROC curve, outperforming the conventional kinetic measures, including maximum peak enhancement (MPE) and signal enhancement ratio (SER), (AUCs of 0.61 and 0.57 respectively). These findings suggest that our DCE-MRI kinetic statistic features can be used to improve the prediction of axillary node status in breast cancer patients. Such features could ultimately be used as imaging biomarkers to guide personalized treatment choices for women diagnosed with breast cancer.

  2. Improving Brain Magnetic Resonance Image (MRI) Segmentation via a Novel Algorithm based on Genetic and Regional Growth

    PubMed Central

    A., Javadpour; A., Mohammadi

    2016-01-01

    Background Regarding the importance of right diagnosis in medical applications, various methods have been exploited for processing medical images solar. The method of segmentation is used to analyze anal to miscall structures in medical imaging. Objective This study describes a new method for brain Magnetic Resonance Image (MRI) segmentation via a novel algorithm based on genetic and regional growth. Methods Among medical imaging methods, brains MRI segmentation is important due to high contrast of non-intrusive soft tissue and high spatial resolution. Size variations of brain tissues are often accompanied by various diseases such as Alzheimer’s disease. As our knowledge about the relation between various brain diseases and deviation of brain anatomy increases, MRI segmentation is exploited as the first step in early diagnosis. In this paper, regional growth method and auto-mate selection of initial points by genetic algorithm is used to introduce a new method for MRI segmentation. Primary pixels and similarity criterion are automatically by genetic algorithms to maximize the accuracy and validity in image segmentation. Results By using genetic algorithms and defining the fixed function of image segmentation, the initial points for the algorithm were found. The proposed algorithms are applied to the images and results are manually selected by regional growth in which the initial points were compared. The results showed that the proposed algorithm could reduce segmentation error effectively. Conclusion The study concluded that the proposed algorithm could reduce segmentation error effectively and help us to diagnose brain diseases. PMID:27672629

  3. Comparing deflection measurements of a magnetically steerable catheter using optical imaging and MRI

    SciTech Connect

    Lillaney, Prasheel Caton, Curtis; Martin, Alastair J.; Losey, Aaron D.; Evans, Leland; Saeed, Maythem; Cooke, Daniel L.; Wilson, Mark W.; Hetts, Steven W.

    2014-02-15

    Purpose: Magnetic resonance imaging (MRI) is an emerging modality for interventional radiology, giving clinicians another tool for minimally invasive image-guided interventional procedures. Difficulties associated with endovascular catheter navigation using MRI guidance led to the development of a magnetically steerable catheter. The focus of this study was to mechanically characterize deflections of two different prototypes of the magnetically steerable catheterin vitro to better understand their efficacy. Methods: A mathematical model for deflection of the magnetically steerable catheter is formulated based on the principle that at equilibrium the mechanical and magnetic torques are equal to each other. Furthermore, two different image based methods for empirically measuring the catheter deflection angle are presented. The first, referred to as the absolute tip method, measures the angle of the line that is tangential to the catheter tip. The second, referred to the base to tip method, is an approximation that is used when it is not possible to measure the angle of the tangent line. Optical images of the catheter deflection are analyzed using the absolute tip method to quantitatively validate the predicted deflections from the mathematical model. Optical images of the catheter deflection are also analyzed using the base to tip method to quantitatively determine the differences between the absolute tip and base to tip methods. Finally, the optical images are compared to MR images using the base to tip method to determine the accuracy of measuring the catheter deflection using MR. Results: The optical catheter deflection angles measured for both catheter prototypes using the absolute tip method fit very well to the mathematical model (R{sup 2} = 0.91 and 0.86 for each prototype, respectively). It was found that the angles measured using the base to tip method were consistently smaller than those measured using the absolute tip method. The deflection angles measured

  4. Comparing deflection measurements of a magnetically steerable catheter using optical imaging and MRI

    PubMed Central

    Lillaney, Prasheel; Caton, Curtis; Martin, Alastair J.; Losey, Aaron D.; Evans, Leland; Saeed, Maythem; Cooke, Daniel L.; Wilson, Mark W.; Hetts, Steven W.

    2014-01-01

    Purpose: Magnetic resonance imaging (MRI) is an emerging modality for interventional radiology, giving clinicians another tool for minimally invasive image-guided interventional procedures. Difficulties associated with endovascular catheter navigation using MRI guidance led to the development of a magnetically steerable catheter. The focus of this study was to mechanically characterize deflections of two different prototypes of the magnetically steerable catheter in vitro to better understand their efficacy. Methods: A mathematical model for deflection of the magnetically steerable catheter is formulated based on the principle that at equilibrium the mechanical and magnetic torques are equal to each other. Furthermore, two different image based methods for empirically measuring the catheter deflection angle are presented. The first, referred to as the absolute tip method, measures the angle of the line that is tangential to the catheter tip. The second, referred to the base to tip method, is an approximation that is used when it is not possible to measure the angle of the tangent line. Optical images of the catheter deflection are analyzed using the absolute tip method to quantitatively validate the predicted deflections from the mathematical model. Optical images of the catheter deflection are also analyzed using the base to tip method to quantitatively determine the differences between the absolute tip and base to tip methods. Finally, the optical images are compared to MR images using the base to tip method to determine the accuracy of measuring the catheter deflection using MR. Results: The optical catheter deflection angles measured for both catheter prototypes using the absolute tip method fit very well to the mathematical model (R2 = 0.91 and 0.86 for each prototype, respectively). It was found that the angles measured using the base to tip method were consistently smaller than those measured using the absolute tip method. The deflection angles measured

  5. MRI-constrained spectral imaging of benzodiazepine modulation of spontaneous neuromagnetic activity in human cortex.

    PubMed

    Ahveninen, Jyrki; Lin, Fa-Hsuan; Kivisaari, Reetta; Autti, Taina; Hämäläinen, Matti; Stufflebeam, Steven; Belliveau, John W; Kähkönen, Seppo

    2007-04-01

    Spontaneous electromagnetic brain rhythms have been widely used in human neuropharmacology, but their applicability is complicated by the difficulties to localize their origins in the human cortex. Here, we used a novel multi-modal non-invasive imaging approach to localize lorazepam (30 microg/kg i.v.) modulation of cortical generators of spontaneous brain rhythms. Eight healthy subjects were measured with 306-channel magnetoencephalography (MEG) in a double-blind, randomized, placebo-controlled (saline), crossover design. For anatomically realistic source modeling, wavelet-transformed MEG data were combined with high-resolution MRI to constrain the current locations to the cortical mantle, after which individual data were co-registered to surface-based coordinate system for the calculation of group statistical parametric maps of drug effects. The distributed MRI-constrained MEG source estimates demonstrated decreased alpha (10 Hz) activity in and around the parieto-occipital sulcus and in the calcarine sulcus of the occipital lobe, following from increased GABA(A)-inhibition by lorazepam. Anatomically constrained spectral imaging displays the cortical loci of drug effects on oscillatory brain activity, providing a novel tool for human pharmacological neuroimaging.

  6. A review of structural MRI and diffusion tensor imaging in schizotypal personality disorder.

    PubMed

    Hazlett, Erin A; Goldstein, Kim E; Kolaitis, Jeanine C

    2012-02-01

    Individuals with schizotypal personality disorder (SPD) share genetic, phenomenologic, and cognitive abnormalities with people diagnosed with schizophrenia. To date, 15 structural MRI studies of the brain have examined size, and 3 diffusion tensor imaging studies have examined white matter connectivity in SPD. Overall, both types of structural neuroimaging modalities have shown temporal lobe abnormalities similar to those observed in schizophrenia, while frontal lobe regions appear to show more sparing. This intriguing pattern suggests that frontal lobe sparing may suppress psychosis, which is consistent with the idea of a possible neuroprotective factor. In this paper, we review these 18 studies and discuss whether individuals with SPD who both resemble and differ from schizophrenia patients in their phenomenology, share some or all of the structural brain imaging characteristics of schizophrenia. We attempt to group the MRI abnormalities in SPD into three patterns: 1) a spectrum of severity-abnormalities are similar to those observed in schizophrenia but not so severe; 2) a spectrum of region-abnormalities affecting some, but not all, brain regions affected in schizophrenia; and 3) a spectrum of compensation-abnormalities reflecting greater-than-normal white matter volume, possibly serving as a buffer or compensatory mechanism protecting the individual with SPD from the frank psychosis observed in schizophrenia.

  7. Development of High-Field Permanent Magnetic Circuits for NMRI/MRI and Imaging on Mice

    PubMed Central

    Wang, Guangxin; Xie, Huantong; Hou, Shulian; Chen, Wei; Yang, Xiuhong

    2016-01-01

    The high-field permanent magnetic circuits of 1.2 T and 1.5 T with novel magnetic focusing and curved-surface correction are developed. The permanent magnetic circuit comprises a magnetic yoke, main magnetic steel, nonspherical curved-surface magnetic poles, plugging magnetic steel, and side magnetic steel. In this work, a novel shimming method is proposed for the effective correction of base magnetic field (B0) inhomogeneities, which is based on passive shimming on the telescope aspheric cutting, grinding, and fine processing technology of the nonspherical curved-surface magnetic poles and active shimming adding higher-order gradient coils. Meanwhile, the magnetic resonance imaging dedicated alloy with high-saturation magnetic field induction intensity and high electrical resistivity is developed, and nonspherical curved-surface magnetic poles which are made of the dedicated alloy have very good anti-eddy-current effect. In addition, the large temperature coefficient problem of permanent magnet can be effectively controlled by using a high quality temperature controller and deuterium external locking technique. Combining our patents such as gradient coil, RF coil, and integration computer software, two kinds of small animal Micro-MRI instruments are developed, by which the high quality MRI images of mice were obtained. PMID:27034951

  8. Development of High-Field Permanent Magnetic Circuits for NMRI/MRI and Imaging on Mice.

    PubMed

    Wang, Guangxin; Xie, Huantong; Hou, Shulian; Chen, Wei; Yang, Xiuhong

    2016-01-01

    The high-field permanent magnetic circuits of 1.2 T and 1.5 T with novel magnetic focusing and curved-surface correction are developed. The permanent magnetic circuit comprises a magnetic yoke, main magnetic steel, nonspherical curved-surface magnetic poles, plugging magnetic steel, and side magnetic steel. In this work, a novel shimming method is proposed for the effective correction of base magnetic field (B 0) inhomogeneities, which is based on passive shimming on the telescope aspheric cutting, grinding, and fine processing technology of the nonspherical curved-surface magnetic poles and active shimming adding higher-order gradient coils. Meanwhile, the magnetic resonance imaging dedicated alloy with high-saturation magnetic field induction intensity and high electrical resistivity is developed, and nonspherical curved-surface magnetic poles which are made of the dedicated alloy have very good anti-eddy-current effect. In addition, the large temperature coefficient problem of permanent magnet can be effectively controlled by using a high quality temperature controller and deuterium external locking technique. Combining our patents such as gradient coil, RF coil, and integration computer software, two kinds of small animal Micro-MRI instruments are developed, by which the high quality MRI images of mice were obtained.

  9. Functional Imaging of Auditory Cortex in Adult Cats using High-field fMRI

    PubMed Central

    Brown, Trecia A.; Gati, Joseph S.; Hughes, Sarah M.; Nixon, Pam L.; Menon, Ravi S.; Lomber, Stephen G.

    2014-01-01

    Current knowledge of sensory processing in the mammalian auditory system is mainly derived from electrophysiological studies in a variety of animal models, including monkeys, ferrets, bats, rodents, and cats. In order to draw suitable parallels between human and animal models of auditory function, it is important to establish a bridge between human functional imaging studies and animal electrophysiological studies. Functional magnetic resonance imaging (fMRI) is an established, minimally invasive method of measuring broad patterns of hemodynamic activity across different regions of the cerebral cortex. This technique is widely used to probe sensory function in the human brain, is a useful tool in linking studies of auditory processing in both humans and animals and has been successfully used to investigate auditory function in monkeys and rodents. The following protocol describes an experimental procedure for investigating auditory function in anesthetized adult cats by measuring stimulus-evoked hemodynamic changes in auditory cortex using fMRI. This method facilitates comparison of the hemodynamic responses across different models of auditory function thus leading to a better understanding of species-independent features of the mammalian auditory cortex. PMID:24637937

  10. Measuring local flow velocities and biofilm structure in biofilm systems with magnetic resonance imaging (MRI).

    PubMed

    Manz, Bertram; Volke, Frank; Goll, Danile; Horn, Harald

    2003-11-20

    The characterization of substrate transport in the bulk phase and in the biofilm matrix is one of the problems which has to be solved for the verification of biofilm models. Additionally, the surface structure of biofilms has to be described with appropriate parameters. Magnetic resonance imaging (MRI) is one of the promising methods for the investigation of transport phenomena and structure in biofilm systems. The MRI technique allows the noninvasive determination of flow velocities and biofilm structures with a high resolution on the sub-millimeter scale. The presented investigations were carried out for defined heterotrophic biofilms which were cultivated in a tube reactor at a Reynolds number of 2000 and 8000 and a substrate load of 6 and 4 g/m2d glucose. Magnetic resonance imaging provides both structure data of the biofilm surface and flow velocities in the bulk phase and at the bulk/biofilm interface. It is shown that the surface roughness of the biofilms can be determined in one experiment for the complete cross section of the test tubes both under flow and stagnant conditions. Furthermore, the local shear stress was calculated from the measured velocity profiles. In the investigated biofilm systems the local shear stress at the biofilm surface was up to 3 times higher compared to the mean wall shear stress calculated on the base of the mean flow velocity.

  11. Annexin A5-Functionalized Bimodal Nanoparticles for MRI and Fluorescence Imaging of Atherosclerotic Plaques

    PubMed Central

    van Tilborg, Geralda A. F.; Vucic, Esad; Strijkers, Gustav J.; Cormode, David P.; Mani, Venkatesh; Skajaa, Torjus; Reutelingsperger, Chris P. M.; Fayad, Zahi A.; Mulder, Willem J. M.; Nicolay, Klaas

    2011-01-01

    Apoptosis and macrophage burden are believed to correlate with atherosclerotic plaque vulnerability and are therefore considered important diagnostic and therapeutic targets for atherosclerosis. These cell types are characterized by the exposure of phosphatidylserine (PS) at their surface. In the present study, we developed and applied a small micellar fluorescent annexin A5-functionalized nanoparticle for noninvasive magnetic resonance imaging (MRI) of PS exposing cells in atherosclerotic lesions. Annexin A5-mediated target-specificity was confirmed with ellipsometry and in vitro binding to apoptotic Jurkat cells. In vivo T1-weighted MRI of the abdominal aorta in atherosclerotic ApoE−/− mice revealed enhanced uptake of the annexin A5-micelles as compared to control-micelles, which was corroborated with ex vivo near-infrared fluorescence images of excised whole aortas. Confocal laser scanning microscopy (CLSM) demonstrated that the targeted agent was associated with macrophages and apoptotic cells, whereas the nonspecific control agent showed no clear uptake by such cells. In conclusion, the annexin A5-conjugated bimodal micelles displayed potential for noninvasive assessment of cell types that are considered to significantly contribute to plaque instability and therefore may be of great value in the assessment of atherosclerotic lesion phenotype. PMID:20804153

  12. Image segmentation and registration for the analysis of joint motion from 3D MRI

    NASA Astrophysics Data System (ADS)

    Hu, Yangqiu; Haynor, David R.; Fassbind, Michael; Rohr, Eric; Ledoux, William

    2006-03-01

    We report an image segmentation and registration method for studying joint morphology and kinematics from in vivo MRI scans and its application to the analysis of ankle joint motion. Using an MR-compatible loading device, a foot was scanned in a single neutral and seven dynamic positions including maximal flexion, rotation and inversion/eversion. A segmentation method combining graph cuts and level sets was developed which allows a user to interactively delineate 14 bones in the neutral position volume in less than 30 minutes total, including less than 10 minutes of user interaction. In the subsequent registration step, a separate rigid body transformation for each bone is obtained by registering the neutral position dataset to each of the dynamic ones, which produces an accurate description of the motion between them. We have processed six datasets, including 3 normal and 3 pathological feet. For validation our results were compared with those obtained from 3DViewnix, a semi-automatic segmentation program, and achieved good agreement in volume overlap ratios (mean: 91.57%, standard deviation: 3.58%) for all bones. Our tool requires only 1/50 and 1/150 of the user interaction time required by 3DViewnix and NIH Image Plus, respectively, an improvement that has the potential to make joint motion analysis from MRI practical in research and clinical applications.

  13. A permanent MRI magnet for magic angle imaging having its field parallel to the poles

    NASA Astrophysics Data System (ADS)

    McGinley, John V. M.; Ristic, Mihailo; Young, Ian R.

    2016-10-01

    A novel design of open permanent magnet is presented, in which the magnetic field is oriented parallel to the planes of its poles. The paper describes the methods whereby such a magnet can be designed with a field homogeneity suitable for Magnetic Resonance Imaging (MRI). Its primary purpose is to take advantage of the Magic Angle effect in MRI of human extremities, particularly the knee joint, by being capable of rotating the direction of the main magnetic field B0 about two orthogonal axes around a stationary subject and achieve all possible angulations. The magnet comprises a parallel pair of identical profiled arrays of permanent magnets backed by a flat steel yoke such that access in lateral directions is practical. The paper describes the detailed optimization procedure from a target 150 mm DSV to the achievement of a measured uniform field over a 130 mm DSV. Actual performance data of the manufactured magnet, including shimming and a sample image, is presented. The overall magnet system mounting mechanism is presented, including two orthogonal axes of rotation of the magnet about its isocentre.

  14. A permanent MRI magnet for magic angle imaging having its field parallel to the poles.

    PubMed

    McGinley, John V M; Ristic, Mihailo; Young, Ian R

    2016-10-01

    A novel design of open permanent magnet is presented, in which the magnetic field is oriented parallel to the planes of its poles. The paper describes the methods whereby such a magnet can be designed with a field homogeneity suitable for Magnetic Resonance Imaging (MRI). Its primary purpose is to take advantage of the Magic Angle effect in MRI of human extremities, particularly the knee joint, by being capable of rotating the direction of the main magnetic field B0 about two orthogonal axes around a stationary subject and achieve all possible angulations. The magnet comprises a parallel pair of identical profiled arrays of permanent magnets backed by a flat steel yoke such that access in lateral directions is practical. The paper describes the detailed optimization procedure from a target 150mm DSV to the achievement of a measured uniform field over a 130mm DSV. Actual performance data of the manufactured magnet, including shimming and a sample image, is presented. The overall magnet system mounting mechanism is presented, including two orthogonal axes of rotation of the magnet about its isocentre.

  15. A framework for accurate determination of the T₂ distribution from multiple echo magnitude MRI images.

    PubMed

    Bai, Ruiliang; Koay, Cheng Guan; Hutchinson, Elizabeth; Basser, Peter J

    2014-07-01

    Measurement of the T2 distribution in tissues provides biologically relevant information about normal and abnormal microstructure and organization. Typically, the T2 distribution is obtained by fitting the magnitude MR images acquired by a multi-echo MRI pulse sequence using an inverse Laplace transform (ILT) algorithm. It is well known that the ideal magnitude MR signal follows a Rician distribution. Unfortunately, studies attempting to establish the validity and efficacy of the ILT algorithm assume that these input signals are Gaussian distributed. Violation of the normality (or Gaussian) assumption introduces unexpected artifacts, including spurious cerebrospinal fluid (CSF)-like long T2 components; bias of the true geometric mean T2 values and in the relative fractions of various components; and blurring of nearby T2 peaks in the T2 distribution. Here we apply and extend our previously proposed magnitude signal transformation framework to map noisy Rician-distributed magnitude multi-echo MRI signals into Gaussian-distributed signals with high accuracy and precision. We then perform an ILT on the transformed data to obtain an accurate T2 distribution. Additionally, we demonstrate, by simulations and experiments, that this approach corrects the aforementioned artifacts in magnitude multi-echo MR images over a large range of signal-to-noise ratios.

  16. Penile fracture: penoscrotal approach with degloving of penis after Magnetic Resonance Imaging (MRI).

    PubMed

    Antonini, Gabriele; Vicini, Patrizio; Sansalone, Salvatore; Garaffa, Giulio; Vitarelli, Antonio; De Berardinis, Ettore; Von Heland, Magnus; Giovannone, Riccardo; Casciani, Emanuele; Gentile, Vincenzo

    2014-03-28

    Fracture of the penis, a relatively uncommon emergency in Urology, consists in the traumatic rupture of the tunica albuginea of the corpus cavernosum. Examination and clinical history can be highly suspicious of penile fracture in the majority of cases and ultrasonography (USS) can be useful to identify the exact location of the tunical rupture, which is proximal in 2/3 of cases and therefore manageable through a penoscrotal approach. Although expensive and not readily available in the acute setting, Magnetic Resonance Imaging (MRI) may play a role in the differential diagnosis with rupture of a circumflex or dorsal vein of the penis or when the tunical rupture is not associated with tear of the overlying Buck's fascia. This form of imaging is more sensitive than USS at identifying the presence of a tunical tear. The treatment of choice is immediate surgical repair, which allows preserving erectile function and minimizing corporeal fibrosis.

  17. MRI-Derived 3-D-Printed Breast Phantom for Microwave Breast Imaging Validation

    PubMed Central

    Burfeindt, Matthew J.; Colgan, Timothy J.; Mays, R. Owen; Shea, Jacob D.; Behdad, Nader; Van Veen, Barry D.; Hagness, Susan C.

    2014-01-01

    We propose a 3-D-printed breast phantom for use in preclinical experimental microwave imaging studies. The phantom is derived from an MRI of a human subject; thus, it is anthropomorphic, and its interior is very similar to an actual distribution of fibroglandular tissues. Adipose tissue in the breast is represented by the solid plastic (printed) regions of the phantom, while fibroglandular tissue is represented by liquid-filled voids in the plastic. The liquid is chosen to provide a biologically relevant dielectric contrast with the printed plastic. Such a phantom enables validation of microwave imaging techniques. We describe the procedure for generating the 3-D-printed breast phantom and present the measured dielectric properties of the 3-D-printed plastic over the frequency range 0.5–3.5 GHz. We also provide an example of a suitable liquid for filling the fibroglandular voids in the plastic. PMID:25132808

  18. Imaging in juvenile idiopathic arthritis (JIA): an update with particular emphasis on MRI.

    PubMed

    Damasio, Maria Beatrice; de Horatio, L Tanturri; Boavida, P; Lambot-Juhan, K; Rosendahl, K; Tomà, P; Muller, Ls Ording

    2013-11-01

    Juvenile idiopathic arthritis (JIA) is a heterogeneous condition encompassing all forms of chronic arthritis of unknown origin and with onset before 16 years of age. During the last decade new, potent therapeutic agents have become available, underscoring the need for accurate monitoring of therapeutic response on both disease activity and structural damage to the joint. However, so far, treatment efficacy is based on clinical ground only, although clinical parameters are poor markers for disease activity and progression of structural damage. Not so for rheumatoid arthritis patients where the inclusion of radiographic assessment has been required by FDA to test the disease-modifying potential of new anti-rheumatic drugs. In imaging of children with JIA there has been a shift from traditional radiography towards newer techniques such as ultrasound and MRI, however without proper evaluation of their accuracy and validity. We here summarize present knowledge and discuss future challenges in imaging children with JIA.

  19. MRI-Derived 3-D-Printed Breast Phantom for Microwave Breast Imaging Validation.

    PubMed

    Burfeindt, Matthew J; Colgan, Timothy J; Mays, R Owen; Shea, Jacob D; Behdad, Nader; Van Veen, Barry D; Hagness, Susan C

    2012-01-01

    We propose a 3-D-printed breast phantom for use in preclinical experimental microwave imaging studies. The phantom is derived from an MRI of a human subject; thus, it is anthropomorphic, and its interior is very similar to an actual distribution of fibroglandular tissues. Adipose tissue in the breast is represented by the solid plastic (printed) regions of the phantom, while fibroglandular tissue is represented by liquid-filled voids in the plastic. The liquid is chosen to provide a biologically relevant dielectric contrast with the printed plastic. Such a phantom enables validation of microwave imaging techniques. We describe the procedure for generating the 3-D-printed breast phantom and present the measured dielectric properties of the 3-D-printed plastic over the frequency range 0.5-3.5 GHz. We also provide an example of a suitable liquid for filling the fibroglandular voids in the plastic.

  20. SU-E-J-144: MRI Visualization of a Metallic Fiducial Marker Used for Image Guided Prostate Radiotherapy

    SciTech Connect

    Yee, S; Krauss, D; Yan, D

    2014-06-01

    Purpose: Unlike on the daily CBCT used for the image-guided radiation therapy, the visualization of an implantable metallic fiducial marker on the planning MRI images has been a challenge due to the inherent insensitivity of metal in MRI, and very thin (∼ 1 mm or less) diameter. Here, an MRI technique to visualize a marker used for prostate cancer radiotherapy is reported. Methods: During the MRI acquisitions, a multi-shot turbo spin echo (TSE) technique (TR=3500 ms, TE=8.6 ms, ETL=17, recon voxel=0.42x0.42x3.5 mm3) was acquired in Philips 3T Ingenia together with a T2-weighted multi-shot TSE (TR=5381 ms, TE=110 ms, ETL=17, recon voxel=0.47×0.47×3 mm3) and a balanced turbo field echo (bTFE, flip angle 60, TR=2.76 ms, TE=1.3 ms, 0.85×0.85×3 mm3, NSA=4). In acquiring the MRI to visualize the fiducial marker, a particular emphasis was made to improve the spatial resolution and visibility in the generally dark, inhomogeneous prostate area by adjusting the slice profile ordering and TE values of TSE acquisition (in general, the lower value of TE in TSE acquisition generates a brighter signal but at the cost of high spatial resolution since the k-space, responsible for high spatial resolution, is filled with noisier data). Results: While clearly visible in CT, the marker was not visible in either T2-weighted TSE or bTFE, although the image qualities of both images were superior. In the new TSE acquisition (∼ a proton-density weighted image) adjusted by changing the profile ordering and the TE value, the marker was visible as a negative (but clear) contrast in the magnitude MRI, and as a positive contrast in the imaginary image of the phase-sensitive MRI. Conclusion: A metallic fiducial marker used for image guidance before prostate cancer radiotherapy can be made visible in MRI, which may facilitate more use of MRI in planning and guiding such radiation therapy.

  1. PCA and level set based non-rigid image registration for MRI and Paxinos-Watson atlas of rat brain

    NASA Astrophysics Data System (ADS)

    Cai, Chao; Liu, Ailing; Ding, Mingyue; Zhou, Chengping

    2007-12-01

    Image registration provides the ability to geometrically align one dataset with another. It is a basic task in a great variety of biomedical imaging applications. This paper introduced a novel three-dimensional registration method for Magnetic Resonance Image (MRI) and Paxinos-Watson Atlas of rat brain. For the purpose of adapting to a large range and non-linear deformation between MRI and atlas in higher registration accuracy, based on the segmentation of rat brain, we chose the principle components analysis (PCA) automatically performing the linear registration, and then, a level set based nonlinear registration correcting some small distortions. We implemented this registration method in a rat brain 3D reconstruction and analysis system. Experiments have demonstrated that this method can be successfully applied to registering the low resolution and noise affection MRI with Paxinos-Watson Atlas of rat brain.

  2. Interleaved EPI Based fMRI Improved by Multiplexed Sensitivity Encoding (MUSE) and Simultaneous Multi-Band Imaging

    PubMed Central

    Chang, Hing-Chiu; Gaur, Pooja; Chou, Ying-hui; Chu, Mei-Lan; Chen, Nan-kuei

    2014-01-01

    Functional magnetic resonance imaging (fMRI) is a non-invasive and powerful imaging tool for detecting brain activities. The majority of fMRI studies are performed with single-shot echo-planar imaging (EPI) due to its high temporal resolution. Recent studies have demonstrated that, by increasing the spatial-resolution of fMRI, previously unidentified neuronal networks can be measured. However, it is challenging to improve the spatial resolution of conventional single-shot EPI based fMRI. Although multi-shot interleaved EPI is superior to single-shot EPI in terms of the improved spatial-resolution, reduced geometric distortions, and sharper point spread function (PSF), interleaved EPI based fMRI has two main limitations: 1) the imaging throughput is lower in interleaved EPI; 2) the magnitude and phase signal variations among EPI segments (due to physiological noise, subject motion, and B0 drift) are translated to significant in-plane aliasing artifact across the field of view (FOV). Here we report a method that integrates multiple approaches to address the technical limitations of interleaved EPI-based fMRI. Firstly, the multiplexed sensitivity-encoding (MUSE) post-processing algorithm is used to suppress in-plane aliasing artifacts resulting from time-domain signal instabilities during dynamic scans. Secondly, a simultaneous multi-band interleaved EPI pulse sequence, with a controlled aliasing scheme incorporated, is implemented to increase the imaging throughput. Thirdly, the MUSE algorithm is then generalized to accommodate fMRI data obtained with our multi-band interleaved EPI pulse sequence, suppressing both in-plane and through-plane aliasing artifacts. The blood-oxygenation-level-dependent (BOLD) signal detectability and the scan throughput can be significantly improved for interleaved EPI-based fMRI. Our human fMRI data obtained from 3 Tesla systems demonstrate the effectiveness of the developed methods. It is expected that future fMRI studies requiring high

  3. In vivo imaging of tau pathology using multi-parametric quantitative MRI

    PubMed Central

    Wells, J.A.; O'Callaghan, J.M.; Holmes, H.E.; Powell, N.M.; Johnson, R.A.; Siow, B.; Torrealdea, F.; Ismail, O.; Walker-Samuel, S.; Golay, X.; Rega, M.; Richardson, S.; Modat, M.; Cardoso, M.J.; Ourselin, S.; Schwarz, A.J.; Ahmed, Z.; Murray, T.K.; O'Neill, M.J.; Collins, E.C.; Colgan, N.; Lythgoe, M.F.

    2015-01-01

    As the number of people diagnosed with Alzheimer's disease (AD) reaches epidemic proportions, there is an urgent need to develop effective treatment strategies to tackle the social and economic costs of this fatal condition. Dozens of candidate therapeutics are currently being tested in clinical trials, and compounds targeting the aberrant accumulation of tau proteins into neurofibrillary tangles (NFTs) are the focus of substantial current interest. Reliable, translatable biomarkers sensitive to both tau pathology and its modulation by treatment along with animal models that faithfully reflect aspects of the human disease are urgently required. Magnetic resonance imaging (MRI) is well established as a valuable tool for monitoring the structural brain changes that accompany AD progression. However the descent into dementia is not defined by macroscopic brain matter loss alone: non-invasive imaging measurements sensitive to protein accumulation, white matter integrity and cerebral haemodynamics probe distinct aspects of AD pathophysiology and may serve as superior biomarkers for assessing drug efficacy. Here we employ a multi-parametric array of five translatable MRI techniques to characterise the in vivo pathophysiological phenotype of the rTg4510 mouse model of tauopathy (structural imaging, diffusion tensor imaging (DTI), arterial spin labelling (ASL), chemical exchange saturation transfer (CEST) and glucose CEST). Tau-induced pathological changes included grey matter atrophy, increased radial diffusivity in the white matter, decreased amide proton transfer and hyperperfusion. We demonstrate that the above markers unambiguously discriminate between the transgenic group and age-matched controls and provide a comprehensive profile of the multifaceted neuropathological processes underlying the rTg4510 model. Furthermore, we show that ASL and DTI techniques offer heightened sensitivity to processes believed to precede detectable structural changes and, as such

  4. Comparison of manual vs. automated multimodality (CT-MRI) image registration for brain tumors

    SciTech Connect

    Sarkar, Abhirup; Santiago, Roberto J.; Smith, Ryan; Kassaee, Alireza . E-mail: Kassaee@xrt.upenn.edu

    2005-03-31

    Computed tomgoraphy-magnetic resonance imaging (CT-MRI) registrations are routinely used for target-volume delineation of brain tumors. We clinically use 2 software packages based on manual operation and 1 automated package with 2 different algorithms: chamfer matching using bony structures, and mutual information using intensity patterns. In all registration algorithms, a minimum of 3 pairs of identical anatomical and preferably noncoplanar landmarks is used on each of the 2 image sets. In manual registration, the program registers these points and links the image sets using a 3-dimensional (3D) transformation. In automated registration, the 3 landmarks are used as an initial starting point and further processing is done to complete the registration. Using our registration packages, registration of CT and MRI was performed on 10 patients. We scored the results of each registration set based on the amount of time spent, the accuracy reported by the software, and a final evaluation. We evaluated each software program by measuring the residual error between 'matched' points on the right and left globes and the posterior fossa for fused image slices. In general, manual registration showed higher misalignment between corresponding points compared to automated registration using intensity matching. This error had no directional dependence and was, most of the time, larger for a larger structure in both registration techniques. Automated algorithm based on intensity matching also gave the best results in terms of registration accuracy, irrespective of whether or not the initial landmarks were chosen carefully, when compared to that done using bone matching algorithm. Intensity-matching algorithm required the least amount of user-time and provided better accuracy.

  5. An image analysis pipeline for the semi-automated analysis of clinical fMRI images based on freely available software.

    PubMed

    Karmonik, Christof; York, Michele; Grossman, Robert; Kakkar, Ekta; Patel, Krutina; Haykal, Hani; King, David

    2010-03-01

    The technique of functional Magnetic Resonance Imaging (fMRI) has evolved in the last 15 years from a research concept into a clinically relevant medical procedure. In this study, an efficient, semi-automated and cost-effective solution for the analysis of fMRI images acquired in a clinical setting is presented relying heavily on open source software. The core of the pipeline is the software Analysis of Functional NeuroImages (AFNI, National Institute of Mental Health (NIMH)) combined with K-PACS and ImageJ. Its application is illustrated with clinical fMRI exams and with a research study involving comparing subjects diagnosed with Parkinson's disease and age-matched controls.

  6. [Magnetic resonance imaging (MRI) in children and adolescents – study design of a feasibility study concerning examination related emotions].

    PubMed

    Jaite, Charlotte; Bachmann, Christian; Dewey, Marc; Weschke, Bernhard; Spors, Birgit; von Moers, Arpad; Napp, Adriane; Lehmkuhl, Ulrike; Kappel, Viola

    2013-11-01

    Numerous research centres apply magnetic resonance imaging (MRI) for research purposes in children. In view of this practical research, ethical concerns regarding the strains the study participants are exposed to during the MRI examination are discussed. The study evaluates whether an MRI examination induces negative emotions in children and adolescents which are more intense than the ones caused by electroencephalography (EEG), an examination method currently classified as causing "minimal stress." Furthermore, the emotional stress induced by the MRI examination in children and adolescents is compared with that induced in adults. The study gathers data on examination-related emotions in children (age 8-17;11, male and female) who undergo an MRI examination of the cerebrum with a medical indication. The comparison group is a sample of children and adolescents examined with EEG (age 8-17;11, male and female) as well as a sample of adults (age 18-65, male and female) examined with MRI. At present, the study is in the stage of data collection. This article presents the study design of the MRI research project.

  7. Fluoroscopically guided extraforaminal cervical nerve root blocks: analysis of epidural flow of the injectate with respect to needle tip position.

    PubMed

    Shipley, Kyle; Riew, K Daniel; Gilula, Louis A

    2014-02-01

    Study Design Retrospective evaluation of consecutively performed fluoroscopically guided cervical nerve root blocks. Objective To describe the incidence of injectate central epidural flow with respect to needle tip position during fluoroscopically guided extraforaminal cervical nerve root blocks (ECNRBs). Methods Between February 19, 2003 and June 11, 2003, 132 consecutive fluoroscopically guided ECNRBs performed with contrast media in the final injected material (injectate) were reviewed on 95 patients with average of 1.3 injections per patient. Fluoroscopic spot images documenting the procedure were obtained as part of standard quality assurance. An independent observer not directly involved in the procedures retrospectively reviewed the images, and the data were placed into a database. Image review was performed to determine optimal needle tip positioning for injectate epidural flow. Results Central epidural injectate flow was obtained in only 28.9% of injections with the needle tip lateral to midline of the lateral mass (zone 2). 83.8% of injectate went into epidural space when the needle tip was medial to midline of the lateral mass (zone 3). 100% of injectate flowed epidurally when the needle tip was medial to or at the medial cortex of the lateral mass (zone 4). There was no statistically significant difference with regards to central epidural flow and the needle tip position on lateral view. Conclusion To ensure central epidural flow with ECNRBs one must be prepared to pass the needle tip medial to midplane of the lateral mass or to medial cortex of the lateral mass. Approximately 16% of ECNRBs with needle tip medial to midline of the lateral mass did not flow into epidural space. One cannot claim a nerve block is an epidural block unless epidural flow of injectate is observed.

  8. 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.

  9. Thermal conduction tensor imaging and energy flow analysis of brain: a feasibility study using MRI.

    PubMed

    Khundrakpam, Budhachandra S; Shukla, Vinay K; Roy, Prasun K

    2010-10-01

    The imaging of the distribution of thermal conductivity tensor at various points in a tissue is an essential need when accurate knowledge of heat energy flow in tissue is required for diagnostic and therapeutic management in oncology, neurology, and interventional radiology. Conventionally, tissue thermal conductivity is assumed as scalar, which induces errors in obtaining proper heat flow distribution. Using statistical thermodynamics principles, we present a method for constructing thermal conductivity tensor image of a tissue or an organ, using an MRI scanner. We elucidate the necessary tensorial cross-property relationship between different transport processes and confirm the same by experimental data. Using the proposed method, we perform a preliminary study of the procedure of thermal conductivity tensor imaging of the human brain as a case study. The methodology is quantitatively elucidated by measurement of tissue anisotropy distribution, tensor eigenvalues, and path tracking, along with three illustrative examples showing that transport properties estimated by the proposed thermal conductivity approach closely corroborates, with over 90% accuracy, to the experimentally measured values of the transport parameters which have been independently experimentally measured directly. By combining diffusion and perfusion tensor imaging approaches using mobility-encoding and spin-labelling methodologies respectively, we delineate the possible applications of this novel imaging modality to clinical problems of energy flow mapping involving biological heat transfer equations, such as planning of hyperthermic treatment to brain tumors, and electrode localization for deep brain stimulation in Parkinson's disease.

  10. A survey of MRI-based medical image analysis for brain tumor studies.

    PubMed

    Bauer, Stefan; Wiest, Roland; Nolte, Lutz-P; Reyes, Mauricio

    2013-07-07

    MRI-based medical image analysis for brain tumor studies is gaining attention in recent times due to an increased need for efficient and objective evaluation of large amounts of data. While the pioneering approaches applying automated methods for the analysis of brain tumor images date back almost two decades, the current methods are becoming more mature and coming closer to routine clinical application. This review aims to provide a comprehensive overview by giving a brief introduction to brain tumors and imaging of brain tumors first. Then, we review the state of the art in segmentation, registration and modeling related to tumor-bearing brain images with a focus on gliomas. The objective in the segmentation is outlining the tumor including its sub-compartments and surrounding tissues, while the main challenge in registration and modeling is the handling of morphological changes caused by the tumor. The qualities of different approaches are discussed with a focus on methods that can be applied on standard clinical imaging protocols. Finally, a critical assessment of the current state is performed and future developments and trends are addressed, giving special attention to recent developments in radiological tumor assessment guidelines.

  11. A survey of MRI-based medical image analysis for brain tumor studies

    NASA Astrophysics Data System (ADS)

    Bauer, Stefan; Wiest, Roland; Nolte, Lutz-P.; Reyes, Mauricio

    2013-07-01

    MRI-based medical image analysis for brain tumor studies is gaining attention in recent times due to an increased need for efficient and objective evaluation of large amounts of data. While the pioneering approaches applying automated methods for the analysis of brain tumor images date back almost two decades, the current methods are becoming more mature and coming closer to routine clinical application. This review aims to provide a comprehensive overview by giving a brief introduction to brain tumors and imaging of brain tumors first. Then, we review the state of the art in segmentation, registration and modeling related to tumor-bearing brain images with a focus on gliomas. The objective in the segmentation is outlining the tumor including its sub-compartments and surrounding tissues, while the main challenge in registration and modeling is the handling of morphological changes caused by the tumor. The qualities of different approaches are discussed with a focus on methods that can be applied on standard clinical imaging protocols. Finally, a critical assessment of the current state is performed and future developments and trends are addressed, giving special attention to recent developments in radiological tumor assessment guidelines.

  12. Histological Basis of Laminar MRI Patterns in High Resolution Images of Fixed Human Auditory Cortex

    PubMed Central

    Wallace, Mark N.; Cronin, Matthew J.; Bowtell, Richard W.; Scott, Ian S.; Palmer, Alan R.; Gowland, Penny A.

    2016-01-01

    Functional magnetic resonance imaging (fMRI) studies of the auditory region of the temporal lobe would benefit from the availability of image contrast that allowed direct identification of the primary auditory cortex, as this region cannot be accurately located using gyral landmarks alone. Previous work has suggested that the primary area can be identified in magnetic resonance (MR) images because of its relatively high myelin content. However, MR images are also affected by the iron content of the tissue and in this study we sought to confirm that different MR image contrasts did correlate with the myelin content in the gray matter and were not primarily affected by iron content as is the case in the primary visual and somatosensory areas. By imaging blocks of fixed post-mortem cortex in a 7 T scanner and then sectioning them for histological staining we sought to assess the relative contribution of myelin and iron to the gray matter contrast in the auditory region. Evaluating the image contrast in T2*-weighted images and quantitative R2* maps showed a reasonably high correlation between the myelin density of the gray matter and the intensity of the MR images. The correlation with T1-weighted phase sensitive inversion recovery (PSIR) images was better than with the previous two image types, and there were clearly differentiated borders between adjacent cortical areas in these images. A significant amount of iron was present in the auditory region, but did not seem to contribute to the laminar pattern of the cortical gray matter in MR images. Similar levels of iron were present in the gray and white matter and although iron was present in fibers within the gray matter, these fibers were fairly uniformly distributed across the cortex. Thus, we conclude that T1- and T2*-weighted imaging sequences do demonstrate the relatively high myelin levels that are characteristic of the deep layers in primary auditory cortex and allow it and some of the surrounding areas to be

  13. Post-mortem CT and MRI: appropriate post-mortem imaging appearances and changes related to cardiopulmonary resuscitation

    PubMed Central

    Dean, Jonathan

    2016-01-01

    Post-mortem cross-sectional imaging in the form of CT and, less frequently, MRI is an emerging facility in the evaluation of cause-of-death and human identification for the coronial service as well as in assisting the forensic investigation of suspicious deaths and homicide. There are marked differences between the radiological evaluation and interpretation of the CT and MRI features of the live patient (i.e. antemortem imaging) and the evaluation and interpretation of post-mortem CT and MRI appearances. In addition to the absence of frequently utilized tissue enhancement following intravenous contrast administration in antemortem imaging, there are a number of variable changes which occur in the tissues and organs of the body as a normal process following death, some of which are, in addition, affected significantly by environmental factors. Many patients and victims will also have undergone aggressive attempts at cardiopulmonary resuscitation in the perimortem period which will also significantly alter post-mortem CT and MRI appearances. It is paramount that the radiologist and pathologist engaged in the interpretation of such post-mortem imaging are familiar with the appropriate non-pathological imaging changes germane to death, the post-mortem interval and cardiopulmonary resuscitation in order to avoid erroneously attributing such changes to trauma or pathology. Some of the more frequently encountered radiological imaging considerations of this nature will be reviewed. PMID:26562099

  14. Fast pseudo-CT synthesis from MRI T1-weighted images using a patch-based approach

    NASA Astrophysics Data System (ADS)

    Torrado-Carvajal, A.; Alcain, E.; Montemayor, A. S.; Herraiz, J. L.; Rozenholc, Y.; Hernandez-Tamames, J. A.; Adalsteinsson, E.; Wald, L. L.; Malpica, N.

    2015-12-01

    MRI-based bone segmentation is a challenging task because bone tissue and air both present low signal intensity on MR images, making it difficult to accurately delimit the bone boundaries. However, estimating bone from MRI images may allow decreasing patient ionization by removing the need of patient-specific CT acquisition in several applications. In this work, we propose a fast GPU-based pseudo-CT generation from a patient-specific MRI T1-weighted image using a group-wise patch-based approach and a limited MRI and CT atlas dictionary. For every voxel in the input MR image, we compute the similarity of the patch containing that voxel with the patches of all MR images in the database, which lie in a certain anatomical neighborhood. The pseudo-CT is obtained as a local weighted linear combination of the CT values of the corresponding patches. The algorithm was implemented in a GPU. The use of patch-based techniques allows a fast and accurate estimation of the pseudo-CT from MR T1-weighted images, with a similar accuracy as the patient-specific CT. The experimental normalized cross correlation reaches 0.9324±0.0048 for an atlas with 10 datasets. The high NCC values indicate how our method can accurately approximate the patient-specific CT. The GPU implementation led to a substantial decrease in computational time making the approach suitable for real applications.

  15. Imaging After GliaSite Brachytherapy: Prognostic MRI Indicators of Disease Control and Recurrence

    SciTech Connect

    Kleinberg, Lawrence; Yoon, Geoffrey; Weingart, John D.; Parisi, Michele; Olivi, Alessandro; Detorie, Nicholas A.; Chan, Timothy A.

    2009-12-01

    Purpose: In this study, we analyzed the magnetic resonance imaging (MRI) changes in patients after GliaSite treatment and characterized the prognostic MRI indicators in these patients. Methods and Materials: A total of 25 patients with recurrent glioblastoma multiforme were treated with the GliaSite Radiation Therapy System. Patients at the Johns Hopkins Hospital with recurrent glioblastoma multiforme underwent surgical resection followed by GliaSite balloon implantation. Available MRI scans for 20 patients were obtained throughout the post-GliaSite treatment course. These were reviewed and analyzed for prognostic significance. Results: After GliaSite treatment, all patients developed some degree of T{sub 1}-weighted contrast and T{sub 2}-weighted hyperintensity around the resection cavity. The development of enhancement on T{sub 1}-weighted contrast-enhanced imaging and the size of these lesions, in the absence of increasing T{sub 2}-weighted hyperintensity, before clinical progression was not associated with decreased survival. Patients with T{sub 1}-weighted enhancement >1 cm had a median survival of 13.6 months and those with T{sub 1}-weighted lesions <=1 cm had a median survival of 8.5 months (p = .014). In contrast, the development of larger areas of T{sub 2}-weighted hyperintensity surrounding the resection cavity was significantly associated with poorer survival (p = .027). Conclusion: After GliaSite treatment, characteristic T{sub 1}- and T{sub 2}-weighted changes are seen on MRI. Greater T{sub 1}-weighted changes in the absence of increasing edema appears not to indicate disease progression; however, greater T{sub 2}-weighted changes were associated with decreased survival. These findings suggest that T{sub 1}-weighted enhancement in the absence of concomitant edema after GliaSite treatment might represent pseudoprogression. Conversely, increasing T{sub 2}-weighted hyperintensity might reflect infiltrative disease progression. These results provide a

  16. Monitoring the Growth of an Orthotopic Tumour Xenograft Model: Multi-Modal Imaging Assessment with Benchtop MRI (1T), High-Field MRI (9.4T), Ultrasound and Bioluminescence

    PubMed Central

    Stuckey, Daniel J.; David, Anna L.; Pedley, R. Barbara; Lythgoe, Mark F.; Siow, Bernard; Walker-Samuel, Simon

    2016-01-01

    Background Research using orthotopic and transgenic models of cancer requires imaging methods to non-invasively quantify tumour burden. As the choice of appropriate imaging modality is wide-ranging, this study aimed to compare low-field (1T) magnetic resonance imaging (MRI), a novel and relatively low-cost system, against established preclinical techniques: bioluminescence imaging (BLI), ultrasound imaging (US), and high-field (9.4T) MRI. Methods A model of colorectal metastasis to the liver was established in eight mice, which were imaged with each modality over four weeks post-implantation. Tumour burden was assessed from manually segmented regions. Results All four imaging systems provided sufficient contrast to detect tumours in all of the mice after two weeks. No significant difference was detected between tumour doubling times estimated by low-field MRI, ultrasound imaging or high-field MRI. A strong correlation was measured between high-field MRI estimates of tumour burden and all the other modalities (p < 0.001, Pearson). Conclusion These results suggest that both low-field MRI and ultrasound imaging are accurate modalities for characterising the growth of preclinical tumour models. PMID:27223614

  17. Modeling diffusion-weighted MRI as a spatially variant Gaussian mixture: Application to image denoising

    PubMed Central

    Gonzalez, Juan Eugenio Iglesias; Thompson, Paul M.; Zhao, Aishan; Tu, Zhuowen

    2011-01-01

    Purpose: This work describes a spatially variant mixture model constrained by a Markov random field to model high angular resolution diffusion imaging (HARDI) data. Mixture models suit HARDI well because the attenuation by diffusion is inherently a mixture. The goal is to create a general model that can be used in different applications. This study focuses on image denoising and segmentation (primarily the former). Methods: HARDI signal attenuation data are used to train a Gaussian mixture model in which the mean vectors and covariance matrices are assumed to be independent of spatial locations, whereas the mixture weights are allowed to vary at different lattice positions. Spatial smoothness of the data is ensured by imposing a Markov random field prior on the mixture weights. The model is trained in an unsupervised fashion using the expectation maximization algorithm. The number of mixture components is determined using the minimum message length criterion from information theory. Once the model has been trained, it can be fitted to a noisy diffusion MRI volume by maximizing the posterior probability of the underlying noiseless data in a Bayesian framework, recovering a denoised version of the image. Moreover, the fitted probability maps of the mixture components can be used as features for posterior image segmentation. Results: The model-based denoising algorithm proposed here was compared on real data with three other approaches that are commonly used in the literature: Gaussian filtering, anisotropic diffusion, and Rician-adapted nonlocal means. The comparison shows that, at low signal-to-noise ratio, when these methods falter, our algorithm considerably outperforms them. When tractography is performed on the model-fitted data rather than on the noisy measurements, the quality of the output improves substantially. Finally, ventricle and caudate nucleus segmentation experiments also show the potential usefulness of the mixture probability maps for

  18. Development of a combined multifrequency MRI-DOT system for human breast imaging using a priori information

    NASA Astrophysics Data System (ADS)

    Thayer, David; Liu, Ning; Unlu, Burcin; Chen, Jeon-Hor; Su, Min-Ying; Nalcioglu, Orhan; Gulsen, Gultekin

    2010-02-01

    Breast cancer is a significant cause of mortality and morbidity among women with early diagnosis being vital to successful treatment. Diffuse Optical Tomography (DOT) is an emerging medical imaging modality that provides information that is complementary to current screening modalities such as MRI and mammography, and may improve the specificity in determining cancer malignancy. Using high-resolution anatomic images as a priori information improves the accuracy of DOT. Measurements are presented characterizing the performance of our system. Preliminary data is also shown illustrating the use of a priori MRI data in phantom studies.ä

  19. Integration of EEG source imaging and fMRI during continuous viewing of natural movies.

    PubMed

    Whittingstall, Kevin; Bartels, Andreas; Singh, Vanessa; Kwon, Soyoung; Logothetis, Nikos K

    2010-10-01

    Electroencephalography (EEG) and functional magnetic resonance imaging (fMRI) are noninvasive neuroimaging tools which can be used to measure brain activity with excellent temporal and spatial resolution, respectively. By combining the neural and hemodynamic recordings from these modalities, we can gain better insight into how and where the brain processes complex stimuli, which may be especially useful in patients with different neural diseases. However, due to their vastly different spatial and temporal resolutions, the integration of EEG and fMRI recordings is not always straightforward. One fundamental obstacle has been that paradigms used for EEG experiments usually rely on event-related paradigms, while fMRI is not limited in this regard. Therefore, here we ask whether one can reliably localize stimulus-driven EEG activity using the continuously varying feature intensities occurring in natural movie stimuli presented over relatively long periods of time. Specifically, we asked whether stimulus-driven aspects in the EEG signal would be co-localized with the corresponding stimulus-driven BOLD signal during free viewing of a movie. Secondly, we wanted to integrate the EEG signal directly with the BOLD signal, by estimating the underlying impulse response function (IRF) that relates the BOLD signal to the underlying current density in the primary visual area (V1). We made sequential fMRI and 64-channel EEG recordings in seven subjects who passively watched 2-min-long segments of a James Bond movie. To analyze EEG data in this natural setting, we developed a method based on independent component analysis (ICA) to reject EEG artifacts due to blinks, subject movement, etc., in a way unbiased by human judgment. We then calculated the EEG source strength of this artifact-free data at each time point of the movie within the entire brain volume using low-resolution electromagnetic tomography (LORETA). This provided for every voxel in the brain (i.e., in 3D space) an

  20. New oil-in-water magnetic emulsion as contrast agent for in vivo magnetic resonance imaging (MRI).

    PubMed

    Ahmed, Naveed; Jaafar-Maalej, Chiraz; Eissa, Mohamed Mahmoud; Fessi, Hatem; Elaissari, Abdelhamid

    2013-09-01

    Nowadays, bio-imaging techniques are widely applied for the diagnosis of various diseased/tumoral tissues in the body using different contrast agents. Accordingly, the advancement in bionanotechnology research is enhanced in this regard. Among contrast agents used, superparamagnetic iron oxide nanoparticles were developed by many researchers and applied for in vive magnetic resonance imaging (MRI). In this study, a new oil-in-water magnetic emulsion was used as contrast agent in MRI, after being characterized in terms of particle size, iron oxide content, magnetic properties and colloidal stability using dynamic light scattering (DLS), thermal gravimetric analysis (TGA), vibrating sample magnetometer (VSM) and zeta potential measurement techniques, respectively. The hydrodynamic size and magnetic content of the magnetic colloidal particles were found to be 250 nm and 75 wt%, respectively. In addition, the used magnetic emulsion possesses superparamagentic properties and high colloidal stability in aqueous medium. Then, the magnetic emulsion was highly diluted and administered intravenously to the Sprague dawley rats to be tested as contrast agent for in vivo MRI. In this preliminary study, MRI images showed significant enhancement in contrast, especially for T2 (relaxation time) contrast enhancement, indicating the distribution of magnetic colloidal nanoparticles within organs, like liver, spleen and kidneys of the Sprague dawley rats. In addition, it was found that 500 microL of the highly diluted magnetic emulsion (0.05 wt%) was found adequate for MRI analysis. This seems to be useful for further investigations especially in theranostic applications of magnetic emulsion.

  1. A multi-slot surface coil for MRI of dual-rat imaging at 4 T

    NASA Astrophysics Data System (ADS)

    Solis, S. E.; Wang, R.; Tomasi, D.; Rodriguez, A. O.

    2011-06-01

    A slotted surface coil inspired by the hole-and-slot cavity magnetron was developed for magnetic resonance imaging of obese rats at 4 T. Full-wave analysis of the magnetic field was carried out at 170 MHz for both the slotted and circular-shaped coils. The noise figure values of two coils were investigated via the numerical calculation of the quality factors. Fat simulated phantoms to mimic overweight rats were included in the analysis with weights ranging from 300 to 900 g. The noise figures were 1.2 dB for the slotted coil and 2.4 dB for the circular coil when loaded with 600 g of simulated phantom. A slotted surface coil with eight circular slots and a circular coil with similar dimensions were built and operated in the transceiver mode, and their performances were experimentally compared. The imaging tests in phantoms demonstrated that the slotted surface coil has a deeper RF-sensitivity and better field uniformity than the single-loop RF-coil. High quality images of two overweight Zucker rats were acquired simultaneously with the slotted surface coil using standard spin-echo pulse sequences. Experimental results showed that the slotted surface coil outperformed the circular coil for imaging considerably overweight rats. Thus, the slotted surface coil can be a good tool for MRI experiments in rats on a human whole-body 4 T scanner.

  2. Automatic classification of dyslexic children by applying machine learning to fMRI images.

    PubMed

    García Chimeno, Yolanda; García Zapirain, Begonya; Saralegui Prieto, Ibone; Fernandez-Ruanova, Begonya

    2014-01-01

    Functional Magnetic Resonance Imaging (fMRI) and Diffusion Tensor Imaging (DTI) are a source of information to study different pathologies. This tool allows to classify subjects under study, analysing in this case, the functions related to language in young patients with dyslexia. Images are obtained using a scanner and different tests are performed on subjects. After processing the images, the areas that are activated by patients when performing the paradigms or anatomy of the tracts were obtained. The main objective is to ultimately introduce a group of monocular vision subjects, whose brain activation model is unknown. This classification helps to assess whether these subjects are more akin to dyslexic or control subjects. Machine learning techniques study systems that learn how to perform non-linear classifications through supervised or unsupervised training, or a combination of both. Once the machine has been set up, it is validated with the subjects who have not been entered in the training stage. The results are obtained using a user-friendly chart. Finally, a new tool for the classification of subjects with dyslexia and monocular vision was obtained (achieving a success rate of 94.8718% on the Neuronal Network classifier), which can be extended to other further classifications.

  3. Whole-body kinetic image of a redox probe in mice using Overhauser-enhanced MRI.

    PubMed

    Kosem, Nuttavut; Naganuma, Tatsuya; Ichikawa, Kazuhiro; Phumala Morales, Noppawan; Yasukawa, Keiji; Hyodo, Fuminori; Yamada, Ken-Ichi; Utsumi, Hideo

    2012-07-15

    Overhauser-enhanced MRI (OMRI) enables visualization of free radicals in animals based on dynamic nuclear polarization. Real-time data of tissue redox status gathered from kinetic images of redox-sensitive nitroxyl radical probes using OMRI provided both anatomic and physiological information. Phantom experiments demonstrated the linear correlation between the enhancement factor and the concentration of a membrane-impermeable probe, carboxy-PROXYL (3-carboxy-2,2,5,5-tetramethyl- pyrrolidine-1-oxyl). Whole-body OMRI images illustrated the in vivo kinetics of carboxy-PROXYL for 25 min. Initial distribution was observed in lung, heart, liver, and kidney, but not brain, corresponding to its minimal lipophilicity. Based on these images (pixel size, 1.33 × 1.33 mm; slice thickness, 50mm), a time-concentration curve with low coefficient of variance (<0.21) was created to assess pharmacokinetic behaviors. A biexponential curve showed a distribution phase from 1 to 10 min and an elimination phase from 15 to 25 min. The α rate constant was greater than the β rate constant in ROIs, confirming that its pharmacokinetics obeyed a two-compartment model. As a noninvasive technique, combining OMRI imaging with redox probes to monitor tissue redox status may be useful in acquiring valuable information regarding organ function for preclinical and clinical studies of oxidative diseases.

  4. In vivo confirmation of hydration based contrast mechanisms for terahertz medical imaging using MRI

    NASA Astrophysics Data System (ADS)

    Bajwa, Neha; Sung, Shijun; Garritano, James; Nowroozi, Bryan; Tewari, Priyamvada; Ennis, Daniel B.; Alger, Jeffery; Grundfest, Warren; Taylor, Zachary

    2014-09-01

    Terahertz (THz) detection has been proposed and applied to a variety of medical imaging applications in view of its unrivaled hydration profiling capabilities. Variations in tissue dielectric function have been demonstrated at THz frequencies to generate high contrast imagery of tissue, however, the source of image contrast remains to be verified using a modality with a comparable sensing scheme. To investigate the primary contrast mechanism, a pilot comparison study was performed in a burn wound rat model, widely known to create detectable gradients in tissue hydration through both injured and surrounding tissue. Parallel T2 weighted multi slice multi echo (T2w MSME) 7T Magnetic Resonance (MR) scans and THz surface reflectance maps were acquired of a full thickness skin burn in a rat model over a 5 hour time period. A comparison of uninjured and injured regions in the full thickness burn demonstrates a 3-fold increase in average T2 relaxation times and a 15% increase in average THz reflectivity, respectively. These results support the sensitivity and specificity of MRI for measuring in vivo burn tissue water content and the use of this modality to verify and understand the hydration sensing capabilities of THz imaging for acute assessments of the onset and evolution of diseases that affect the skin. A starting point for more sophisticated in vivo studies, this preliminary analysis may be used in the future to explore how and to what extent the release of unbound water affects imaging contrast in THz burn sensing.

  5. A multi-slot surface coil for MRI of dual-rat imaging at 4T

    SciTech Connect

    Solis, S.E.; Tomasi, D.; Solis, S.E.; Wang, R.; Tomasi, D.; Rodriguez, A.O.

    2011-07-01

    A slotted surface coil inspired by the hole-and-slot cavity magnetron was developed for magnetic resonance imaging of obese rats at 4 T. Full-wave analysis of the magnetic field was carried out at 170 MHz for both the slotted and circular-shaped coils. The noise figure values of two coils were investigated via the numerical calculation of the quality factors. Fat simulated phantoms to mimic overweight rats were included in the analysis with weights ranging from 300 to 900 g. The noise figures were 1.2 dB for the slotted coil and 2.4 dB for the circular coil when loaded with 600 g of simulated phantom. A slotted surface coil with eight circular slots and a circular coil with similar dimensions were built and operated in the transceiver mode, and their performances were experimentally compared. The imaging tests in phantoms demonstrated that the slotted surface coil has a deeper RF-sensitivity and better field uniformity than the single-loop RF-coil. High quality images of two overweight Zucker rats were acquired simultaneously with the slotted surface coil using standard spin-echo pulse sequences. Experimental results showed that the slotted surface coil outperformed the circular coil for imaging considerably overweight rats. Thus, the slotted surface coil can be a good tool for MRI experiments in rats on a human whole-body 4 T scanner.

  6. Evaluation of novel genetic algorithm generated schemes for positron emission tomography (PET)/magnetic resonance imaging (MRI) image fusion.

    PubMed

    Baum, K G; Schmidt, E; Rafferty, K; Krol, A; Helguera, María

    2011-12-01

    The use and benefits of a multimodality approach in the context of breast cancer imaging are discussed. Fusion techniques that allow multiple images to be viewed simultaneously are discussed. Many of these fusion techniques rely on the use of color tables. A genetic algorithm that generates color tables that have desired properties such as satisfying the order principle, the rows, and columns principle, have perceivable uniformity and have maximum contrast is introduced. The generated 2D color tables can be used for displaying fused datasets. The advantage the proposed method has over other techniques is the ability to consider a much larger set of possible color tables, ensuring that the best one is found. We asked radiologists to perform a set of tasks reading fused PET/MRI breast images obtained using eight different fusion techniques. This preliminary study clearly demonstrates the need and benefit of a joint display by estimating the inaccuracies incurred when using a side-by-side display. The study suggests that the color tables generated by the genetic algorithm are good choices for fusing MR and PET images. It is interesting to note that popular techniques such as the Fire/Gray and techniques based on the HSV color space, which are prevalent in the literature and clinical practice, appear to give poorer performance.

  7. Evaluation of an image-based tracking workflow with Kalman filtering for automatic image plane alignment in interventional MRI.

    PubMed

    Neumann, M; Cuvillon, L; Breton, E; de Matheli, M

    2013-01-01

    Recently, a workflow for magnetic resonance (MR) image plane alignment based on tracking in real-time MR images was introduced. The workflow is based on a tracking device composed of 2 resonant micro-coils and a passive marker, and allows for tracking of the passive marker in clinical real-time images and automatic (re-)initialization using the microcoils. As the Kalman filter has proven its benefit as an estimator and predictor, it is well suited for use in tracking applications. In this paper, a Kalman filter is integrated in the previously developed workflow in order to predict position and orientation of the tracking device. Measurement noise covariances of the Kalman filter are dynamically changed in order to take into account that, according to the image plane orientation, only a subset of the 3D pose components is available. The improved tracking performance of the Kalman extended workflow could be quantified in simulation results. Also, a first experiment in the MRI scanner was performed but without quantitative results yet.

  8. Retrieval of Brain Tumors with Region-Specific Bag-of-Visual-Words Representations in Contrast-Enhanced MRI Images

    PubMed Central

    Huang, Meiyan; Yang, Wei; Yu, Mei; Lu, Zhentai; Feng, Qianjin; Chen, Wufan

    2012-01-01

    A content-based image retrieval (CBIR) system is proposed for the retrieval of T1-weighted contrast-enhanced MRI (CE-MRI) images of brain tumors. In this CBIR system, spatial information in the bag-of-visual-words model and domain knowledge on the brain tumor images are considered for the representation of brain tumor images. A similarity metric is learned through a distance metric learning algorithm to reduce the gap between the visual features and the semantic concepts in an image. The learned similarity metric is then used to measure the similarity between two images and then retrieve the most similar images in the dataset when a query image is submitted to the CBIR system. The retrieval performance of the proposed method is evaluated on a brain CE-MRI dataset with three types of brain tumors (i.e., meningioma, glioma, and pituitary tumor). The experimental results demonstrate that the mean average precision values of the proposed method range from 90.4% to 91.5% for different views (transverse, coronal, and sagittal) with an average value of 91.0%. PMID:23243462

  9. A Comparison of Hyperelastic Warping of PET Images with Tagged MRI for the Analysis of Cardiac Deformation

    DOE PAGES

    Veress, Alexander I.; Klein, Gregory; Gullberg, Grant T.

    2013-01-01

    Tmore » he objectives of the following research were to evaluate the utility of a deformable image registration technique known as hyperelastic warping for the measurement of local strains in the left ventricle through the analysis of clinical, gated PET image datasets.wo normal human male subjects were sequentially imaged with PET and tagged MRI imaging. Strain predictions were made for systolic contraction using warping analyses of the PET images and HARP based strain analyses of the MRI images. Coefficient of determination R 2 values were computed for the comparison of circumferential and radial strain predictions produced by each methodology.here was good correspondence between the methodologies, with R 2 values of 0.78 for the radial strains of both hearts and from an R 2 = 0.81 and R 2 = 0.83 for the circumferential strains.he strain predictions were not statistically different ( P ≤ 0.01 ) . A series of sensitivity results indicated that the methodology was relatively insensitive to alterations in image intensity, random image noise, and alterations in fiber structure.his study demonstrated that warping was able to provide strain predictions of systolic contraction of the LV consistent with those provided by tagged MRI Warping.« less

  10. Accelerating k-t sparse using k-space aliasing for dynamic MRI imaging.

    PubMed

    Pawar, Kamlesh; Egan, Gary F; Zhang, Jingxin

    2013-01-01

    Dynamic imaging is challenging in MRI and acceleration techniques are usually needed to acquire dynamic scene. K-t sparse is an acceleration technique based on compressed sensing, it acquires fewer amounts of data in k-t space by pseudo random ordering of phase encodes and reconstructs dynamic scene by exploiting sparsity of k-t space in transform domain. Another recently introduced technique accelerates dynamic MRI scans by acquiring k-space data in aliased form. K-space aliasing technique uses multiple RF excitation pulses to deliberately acquire aliased k-space data. During reconstruction a simple Fourier transformation along time frames can unaliase the acquired aliased data. This paper presents a novel method to combine k-t sparse and k-space aliasing to achieve higher acceleration than each of the individual technique alone. In this particular combination, a very critical factor of compressed sensing, the ratio of the number of acquired phase encodes to the number of total phase encode (n/N) increases therefore compressed sensing component of reconstruction performs exceptionally well. Comparison of k-t sparse and the proposed technique for acceleration factors of 4, 6 and 8 is demonstrated in simulation on cardiac data.

  11. Discriminative analysis of schizophrenia using support vector machine and recursive feature elimination on structural MRI images

    PubMed Central

    Lu, Xiaobing; Yang, Yongzhe; Wu, Fengchun; Gao, Minjian; Xu, Yong; Zhang, Yue; Yao, Yongcheng; Du, Xin; Li, Chengwei; Wu, Lei; Zhong, Xiaomei; Zhou, Yanling; Fan, Ni; Zheng, Yingjun; Xiong, Dongsheng; Peng, Hongjun; Escudero, Javier; Huang, Biao; Li, Xiaobo; Ning, Yuping; Wu, Kai

    2016-01-01

    Abstract Structural abnormalities in schizophrenia (SZ) patients have been well documented with structural magnetic resonance imaging (MRI) data using voxel-based morphometry (VBM) and region of interest (ROI) analyses. However, these analyses can only detect group-wise differences and thus, have a poor predictive value for individuals. In the present study, we applied a machine learning method that combined support vector machine (SVM) with recursive feature elimination (RFE) to discriminate SZ patients from normal controls (NCs) using their structural MRI data. We first employed both VBM and ROI analyses to compare gray matter volume (GMV) and white matter volume (WMV) between 41 SZ patients and 42 age- and sex-matched NCs. The method of SVM combined with RFE was used to discriminate SZ patients from NCs using significant between-group differences in both GMV and WMV as input features. We found that SZ patients showed GM and WM abnormalities in several brain structures primarily involved in the emotion, memory, and visual systems. An SVM with a RFE classifier using the significant structural abnormalities identified by the VBM analysis as input features achieved the best performance (an accuracy of 88.4%, a sensitivity of 91.9%, and a specificity of 84.4%) in the discriminative analyses of SZ patients. These results suggested that distinct neuroanatomical profiles associated with SZ patients might provide a potential biomarker for disease diagnosis, and machine-learning methods can reveal neurobiological mechanisms in psychiatric diseases. PMID:27472673

  12. Comparative imaging study in ultrasound, MRI, CT, and DSA using a multimodality renal artery phantom

    SciTech Connect

    King, Deirdre M.; Fagan, Andrew J.; Moran, Carmel M.; Browne, Jacinta E.

    2011-02-15

    Purpose: A range of anatomically realistic multimodality renal artery phantoms consisting of vessels with varying degrees of stenosis was developed and evaluated using four imaging techniques currently used to detect renal artery stenosis (RAS). The spatial resolution required to visualize vascular geometry and the velocity detection performance required to adequately characterize blood flow in patients suffering from RAS are currently ill-defined, with the result that no one imaging modality has emerged as a gold standard technique for screening for this disease. Methods: The phantoms, which contained a range of stenosis values (0%, 30%, 50%, 70%, and 85%), were designed for use with ultrasound, magnetic resonance imaging, x-ray computed tomography, and x-ray digital subtraction angiography. The construction materials used were optimized with respect to their ultrasonic speed of sound and attenuation coefficient, MR relaxometry (T{sub 1},T{sub 2}) properties, and Hounsfield number/x-ray attenuation coefficient, with a design capable of tolerating high-pressure pulsatile flow. Fiducial targets, incorporated into the phantoms to allow for registration of images among modalities, were chosen to minimize geometric distortions. Results: High quality distortion-free images of the phantoms with good contrast between vessel lumen, fiducial markers, and background tissue to visualize all stenoses were obtained with each modality. Quantitative assessments of the grade of stenosis revealed significant discrepancies between modalities, with each underestimating the stenosis severity for the higher-stenosed phantoms (70% and 85%) by up to 14%, with the greatest discrepancy attributable to DSA. Conclusions: The design and construction of a range of anatomically realistic renal artery phantoms containing varying degrees of stenosis is described. Images obtained using the main four diagnostic techniques used to detect RAS were free from artifacts and exhibited adequate contrast

  13. The (amorphous) anatomy of an invention: the case of magnetic resonance imaging (MRI).

    PubMed

    Prasad, Amit

    2007-08-01

    The priority dispute between Raymond Damadian and Paul Lauterbur over the 'invention' of magnetic resonance imaging (MRI) has attracted the attention of social and natural scientists for more than 30 years. In this paper, I have used this priority dispute to analyze the complex socio-epistemic processes through which a claim for an invention is made and strengthened. I argue that a tension exists because techno-scientific practices are embedded within a particular disciplinary regime of authorship: even though techno-scientific practices occur through distributed cognition and are contingent upon particular socio-epistemic contexts, a claim for an invention requires assigning authorship to a particular person, company, or institution in order to clearly define the origin and the novelty of that particular techno-scientific event. Nevertheless, the outcomes of socio-epistemic practices for making and strengthening priority claims are shifting, open-ended, and contingent upon particular socio-epistemic contexts.

  14. Magnetic Resonance Imaging (MRI) Analysis of Ischemia/Reperfusion in Experimental Acute Renal Injury.

    PubMed

    Pohlmann, Andreas; Arakelyan, Karen; Seeliger, Erdmann; Niendorf, Thoralf

    2016-01-01

    Imbalance between renal oxygen delivery and demand in the first hours after reperfusion is suggested to be decisive in the pathophysiological chain of events leading to ischemia-induced acute kidney injury. Here we describe blood oxygenation level-dependent (BOLD) magnetic resonance imaging (MRI) for continuous monitoring of the deoxyhemoglobin-sensitive MR parameter T 2* in the renal cortex, outer medulla, and inner medulla of rats throughout renal ischemia/reperfusion (I/R). Changes during I/R are benchmarked against the effects of variations in the fraction of inspired oxygen (hypoxia, hyperoxia). This method may be useful for investigating renal blood oxygenation of rats in vivo under various experimental (patho)physiological conditions.

  15. Two Solutions for Registration of Ultrasound to MRI for Image-Guided Prostate Interventions

    PubMed Central

    Moradi, Mehdi; Janoos, Firdaus; Fedorov, Andriy; Risholm, Petter; Kapur, Tina; Wolfsberger, Luciant D.; Nguyen, Paul L.; Tempany, Clare M; Wells, William M

    2013-01-01

    Ultrasound-guided prostate interventions could benefit from incorporating the radiologic localization of the tumor which can be acquired from multiparametric MRI. To enable this integration, we propose and compare two solutions for registration of T2 weighted MR images with transrectal ultrasound. Firstly, we propose an innovative and practical approach based on deformable registration of binary label maps obtained from manual segmentation of the gland in the two modalities. This resulted in a target registration error of 3.6±1.7 mm. Secondly, we report a novel surface-based registration method that uses a biomechanical model of the tissue and results in registration error of 3.2±1.3 mm. We compare the two methods in terms of accuracy, clinical use and technical limitations. PMID:23366095

  16. Heritability of magnetic resonance imaging (MRI) traits in Alzheimer disease cases and their siblings in the MIRAGE study.

    PubMed

    Lunetta, Kathryn L; Erlich, Porat M; Cuenco, Karen T; Cupples, L Adrienne; Green, Robert C; Farrer, Lindsay A; Decarli, Charles

    2007-01-01

    Magnetic resonance imaging (MRI) traits can serve as more specific measures of degenerative or cerebrovascular brain injury than can be ascertained through personal history, risk factors, clinical signs, or symptoms. They are potentially useful intermediate phenotypes for genetic studies of Alzheimer disease (AD). Recent studies have estimated heritability of white matter hyperintensity (WMH) among cognitively normal family members to be between 0.55 and 0.73. Persons discordant for AD are expected to have substantially different MRI phenotype distributions; our goal was to determine whether MRI traits in siblings discordant for AD are heritable. We measured cerebral atrophy, medial temporal atrophy (MTA), WMH, and a rating of cerebrovascular disease (CVR) via MRI in 815 participants from 424 families of the Multi-Institutional Research in Alzheimer's Genetic Epidemiology Study. Residual heritability after adjustment for covariates ranged from 0.17 (P=0.009) for MTA to 0.57 (P=10(-7)) for CVR. The number of APOE-epsilon4 alleles was significantly associated with WMH (P=0.01) and CVR (P=0.005) but not cerebral atrophy (P=0.25) or MTA (P=0.83). Heritability remained significant and high after adjusting for APOE genotype, suggesting that a substantial proportion of the additive genetic variation in these MRI traits is explained by other genes. In the Multi-Institutional Research in Alzheimer's Genetic Epidemiology Study of AD-discordant siblings, MRI traits are heritable and are potential endophenotypes for genetic association studies.

  17. MRI contrast variation of thermosensitive magnetoliposomes triggered by focused ultrasound: a tool for image-guided local drug delivery.

    PubMed

    Lorenzato, Cyril; Cernicanu, Alexandru; Meyre, Marie-Edith; Germain, Matthieu; Pottier, Agnès; Levy, Laurent; de Senneville, Baudouin Denis; Bos, Clemens; Moonen, Chrit; Smirnov, Pierre

    2013-01-01

    Improved drug delivery control during chemotherapy has the potential to increase the therapeutic index. MRI contrast agent such as iron oxide nanoparticles can be co-encapsulated with drugs in nanocarrier liposomes allowing their tracking and/or visualization by MRI. Furthermore, the combination of a thermosensitive liposomal formulation with an external source of heat such as high intensity focused ultrasound guided by MR temperature mapping allows the controlled local release of the content of the liposome. MRI-guided high-intensity focused ultrasound (HIFU), in combination represents a noninvasive technique to generate local hyperthermia for drug release. In this study we used ultrasmall superparamagnetic iron oxide nanoparticles (USPIO) encapsulated in thermosensitive liposomes to obtain thermosensitive magnetoliposomes (TSM). The transverse and longitudinal relaxivities of this MRI contrast agent were measured upon TSM membrane phase transition in vitro using a water bath or HIFU. The results showed significant differences for MRI signal enhancement and relaxivities before and after heating, which were absent for nonthermosensitive liposomes and free nanoparticles used as controls. Thus, incorporation of USPIO as MRI contrast agents into thermosensitive liposomes should, besides TSM tumor accumulation monitoring, allow the visualization of TSM membrane phase transition upon temperature elevation. In conclusion, HIFU under MR image guidance in combination with USPIO-loaded thermosensitive liposomes as drug delivery system has the potential for a better control of drug delivery and to increase the drug therapeutic index.

  18. Fast Imaging Technique for fMRI: Consecutive Multishot Echo Planar Imaging Accelerated with GRAPPA Technique.

    PubMed

    Kang, Daehun; Sung, Yul-Wan; Kang, Chang-Ki

    2015-01-01

    This study was to evaluate the proposed consecutive multishot echo planar imaging (cmsEPI) combined with a parallel imaging technique in terms of signal-to-noise ratio (SNR) and acceleration for a functional imaging study. We developed cmsEPI sequence using both consecutively acquired multishot EPI segments and variable flip angles to minimize the delay between segments and to maximize the SNR, respectively. We also combined cmsEPI with the generalized autocalibrating partially parallel acquisitions (GRAPPA) method. Temporal SNRs were measured at different acceleration factors and number of segments for functional sensitivity evaluation. We also examined the geometric distortions, which inherently occurred in EPI sequence. The practical acceleration factors, R = 2 or R = 3, of the proposed technique improved the temporal SNR by maximally 18% in phantom test and by averagely 8.2% in in vivo experiment, compared to cmsEPI without parallel imaging. The data collection time was decreased in inverse proportion to the acceleration factor as well. The improved temporal SNR resulted in better statistical power when evaluated on the functional response of the brain. In this study, we demonstrated that the combination of cmsEPI with the parallel imaging technique could provide the improved functional sensitivity for functional imaging study, compensating for the lower SNR by cmsEPI.

  19. Fast Imaging Technique for fMRI: Consecutive Multishot Echo Planar Imaging Accelerated with GRAPPA Technique

    PubMed Central

    Kang, Daehun; Sung, Yul-Wan; Kang, Chang-Ki

    2015-01-01

    This study was to evaluate the proposed consecutive multishot echo planar imaging (cmsEPI) combined with a parallel imaging technique in terms of signal-to-noise ratio (SNR) and acceleration for a functional imaging study. We developed cmsEPI sequence using both consecutively acquired multishot EPI segments and variable flip angles to minimize the delay between segments and to maximize the SNR, respectively. We also combined cmsEPI with the generalized autocalibrating partially parallel acquisitions (GRAPPA) method. Temporal SNRs were measured at different acceleration factors and number of segments for functional sensitivity evaluation. We also examined the geometric distortions, which inherently occurred in EPI sequence. The practical acceleration factors, R = 2 or R = 3, of the proposed technique improved the temporal SNR by maximally 18% in phantom test and by averagely 8.2% in in vivo experiment, compared to cmsEPI without parallel imaging. The data collection time was decreased in inverse proportion to the acceleration factor as well. The improved temporal SNR resulted in better statistical power when evaluated on the functional response of the brain. In this study, we demonstrated that the combination of cmsEPI with the parallel imaging technique could provide the improved functional sensitivity for functional imaging study, compensating for the lower SNR by cmsEPI. PMID:26413518

  20. Development of functional imaging in the human brain (fMRI); the University of Minnesota experience

    PubMed Central

    Uğurbil, Kâmil

    2012-01-01

    The human functional magnetic resonance imaging (fMRI) experiments performed in the Center for Magnetic Resonance Research (CMRR), University of Minnesota, were planned between two colleagues who had worked together previously in Bell Laboratories in the late nineteen seventies, namely myself and Seiji Ogawa. These experiments were motivated by the Blood Oxygenation Level Dependent (BOLD) contrast developed by Seiji. We discussed and planned human studies to explore imaging human brain activity using the BOLD mechanism on the 4 Tesla human system that I was expecting to receive for CMRR. We started these experiments as soon as this 4 Tesla instrument became marginally operational. These were the very first studies performed on the 4 Tesla scanner in CMRR; had the scanner became functional earlier, they would have been started earlier as well. We had positive results certainly by August 1991 annual meeting of the Society of Magnetic Resonance in Medicine (SMRM) and took some of the data with us to that meeting. I believe, however, that neither the MGH colleagues nor us, at the time, had enough data and/or conviction to publish these extraordinary observations; it took more or less another six months or so before the papers from these two groups were submitted for publication within five days of each other to the Proceedings of the National Academy of Sciences, USA, after rejections by Nature. Based on this record, it is fair to say that fMRI was achieved independently and at about the same time at MGH, in an effort credited largely to Ken Kwong, and in CMRR, University of Minnesota in an effort led by myself and Seiji Ogawa. PMID:22342875

  1. A patient specific 4D MRI liver motion model based on sparse imaging and registration

    NASA Astrophysics Data System (ADS)

    Noorda, Y. H.; Bartels, L. W.; van Stralen, Marijn; Pluim, J. P. W.

    2013-03-01

    Introduction: Image-guided minimally invasive procedures are becoming increasingly popular. Currently, High-Intensity Focused Ultrasound (HIFU) treatment of lesions in mobile organs, such as the liver, is in development. A requirement for such treatment is automatic motion tracking, such that the position of the lesion can be followed in real time. We propose a 4D liver motion model, which can be used during planning of this procedure. During treatment, the model can serve as a motion predictor. In a similar fashion, this model could be used for radiotherapy treatment of the liver. Method: The model is built by acquiring 2D dynamic sagittal MRI data at six locations in the liver. By registering these dynamics to a 3D MRI liver image, 2D deformation fields are obtained at every location. The 2D fields are ordered according to the position of the liver at that specific time point, such that liver motion during an average breathing period can be simulated. This way, a sparse deformation field is created over time. This deformation field is finally interpolated over the entire volume, yielding a 4D motion model. Results: The accuracy of the model is evaluated by comparing unseen slices to the slice predicted by the model at that specific location and phase in the breathing cycle. The mean Dice coefficient of the liver regions was 0.90. The mean misalignment of the vessels was 1.9 mm. Conclusion: The model is able to predict patient specific deformations of the liver and can predict regular motion accurately.

  2. Preclinical Feasibility of a Technology Framework for MRI-guided Iliac Angioplasty

    PubMed Central

    Rube, Martin A.; Fernandez-Gutierrez, Fabiola; Cox, Benjamin F.; Holbrook, Andrew B.; Houston, J. Graeme; White, Richard D.; McLeod, Helen; Fatahi, Mahsa; Melzer, Andreas

    2015-01-01

    Purpose Interventional MRI has significant potential for image guidance of iliac angioplasty and related vascular procedures. A technology framework with in-room image display, control, communication and MRI-guided intervention techniques was designed and tested for its potential to provide safe, fast and efficient MRI-guided angioplasty of the iliac arteries. Methods A 1.5T MRI scanner was adapted for interactive imaging during endovascular procedures using new or modified interventional devices such as guidewires and catheters. A perfused vascular phantom was used for testing. Pre-, intra- and post-procedural visualization and measurement of vascular morphology and flow was implemented. A detailed analysis of X-Ray fluoroscopic angiography workflow was conducted and applied. Two interventional radiologists and one physician in training performed 39 procedures. All procedures were timed and analyzed. Results MRI-guided iliac angioplasty procedures were successfully performed with progressive adaptation of techniques and workflow. The workflow, setup and protocol enabled a reduction in table time for a dedicated MRI-guided procedure to 6 min 33 s with a mean procedure time of 9 min 2 s, comparable to the mean procedure time of 8 min 42 s for the standard X-Ray guided procedure. Conclusions MRI-guided iliac vascular interventions were found to be feasible and practical using this framework and optimized workflow. In particular the real-time flow analysis was found to be helpful for pre- and post-interventional assessments. Design optimization of the catheters and in vivo experiments are required before clinical evaluation. PMID:25102933

  3. Perimetric visual field and functional MRI correlation: implications for image-guided surgery in occipital brain tumours

    PubMed Central

    Roux, F; Ibarrola, D; Lotterie, J; Chollet, F; Berry, I

    2001-01-01

    OBJECTIVE—To compare the results of visual functional MRI with those of perimetric evaluation in patients with visual field defects and retrochiasmastic tumours and in normal subjects without visual field defect. The potential clinical usefulness of visual functional MRI data during resective surgery was evaluated in patients with occipital lobe tumours.
METHODS—Eleven patients with various tumours and visual field defects and 12 normal subjects were studied by fMRI using bimonocular or monocular repetitive photic stimulation (8 Hz). The data obtained were analyzed with the statistical parametric maps software (p<10-8) and were compared with the results of Goldmann visual field perimetric evaluation. In patients with occipital brain tumours undergoing surgery, the functional data were registered in a frameless stereotactic device and the images fused into anatomical three standard planes and three dimensional reconstructions of the brain surface.
RESULTS—Two studies of patients were discarded, one because of head motion and the other because of badly followed instructions. On the remaining patients the functional activations found in the visual cortex were consistent with the results of perimetric evaluation in all but one of the patients and all the normal subjects although the results of fMRI were highly dependent on the choices of the analysis thresholds. Visual functional MRI image guided data were used in five patients with occipital brain tumours. No added postoperative functional field defect was detected.
CONCLUSIONS—There was a good correspondence between fMRI data and the results of perimetric evaluation although dependent on the analysis thresholds. Visual fMRI data registered into a frameless stereotactic device may be useful in surgical planning and tumour removal.

 PMID:11561035

  4. Biplane reconstruction and visualization of virtual endoscopic and fluoroscopic views for interventional device navigation

    NASA Astrophysics Data System (ADS)

    Wagner, Martin G.; Strother, Charles M.; Schafer, Sebastian; Mistretta, Charles A.

    2016-03-01

    Biplane fluoroscopic imaging is an important tool for minimally invasive procedures for the treatment of cerebrovascular diseases. However, finding a good working angle for the C-arms of the angiography system as well as navigating based on the 2D projection images can be a difficult task. The purpose of this work is to propose a novel 4D reconstruction algorithm for interventional devices from biplane fluoroscopy images and to propose new techniques for a better visualization of the results. The proposed reconstruction methods binarizes the fluoroscopic images using a dedicated noise reduction algorithm for curvilinear structures and a global thresholding approach. A topology preserving thinning algorithm is then applied and a path search algorithm minimizing the curvature of the device is used to extract the 2D device centerlines. Finally, the 3D device path is reconstructed using epipolar geometry. The point correspondences are determined by a monotonic mapping function that minimizes the reconstruction error. The three dimensional reconstruction of the device path allows the rendering of virtual fluoroscopy images from arbitrary angles as well as 3D visualizations like virtual endoscopic views or glass pipe renderings, where the vessel wall is rendered with a semi-transparent material. This work also proposes a combination of different visualization techniques in order to increase the usability and spatial orientation for the user. A combination of synchronized endoscopic and glass pipe views is proposed, where the virtual endoscopic camera position is determined based on the device tip location as well as the previous camera position using a Kalman filter in order to create a smooth path. Additionally, vessel centerlines are displayed and the path to the target is highlighted. Finally, the virtual endoscopic camera position is also visualized in the glass pipe view to further improve the spatial orientation. The proposed techniques could considerably improve

  5. Temporal comparison of functional brain imaging with diffuse optical tomography and fMRI during rat forepaw stimulation

    NASA Astrophysics Data System (ADS)

    Siegel, Andrew M.; Culver, Joseph P.; Mandeville, Joseph B.; Boas, David A.

    2003-05-01

    The time courses of oxyhaemoglobin ([HbO2]), deoxyhaemoglobin ([HbR]) and total haemoglobin ([HbT]) concentration changes following cortical activation in rats by electrical forepaw stimulation were measured using diffuse optical tomography (DOT) and compared to similar measurements performed previously with fMRI at 2.0 T and 4.7 T. We also explored the qualitative effects of varying stimulus parameters on the temporal evolution of the hemodynamic response. DOT images were reconstructed at a depth of 1.5 mm over a 1 cm square area from 2 mm anterior to bregma to 8 mm posterior to bregma. The measurement set included 9 sources and 16 detectors with an imaging frame rate of 10 Hz. Both DOT [HbR] and [HbO2] time courses were compared to the fMRI BOLD time course during stimulation, and the DOT [HbT] time course was compared to the fMRI cerebral plasma volume (CPV) time course. We believe that DOT and fMRI can provide similar temporal information for both blood volume and deoxyhaemoglobin changes, which helps to cross-validate these two techniques and to demonstrate that DOT can be useful as a complementary modality to fMRI for investigating the hemodynamic response to neuronal activity.

  6. Characterizing populations and searching for diagnostics via elastic registration of MRI images

    NASA Astrophysics Data System (ADS)

    Pettey, David; Gee, James C.

    2001-07-01

    Given image data from two distinct populations and a family of functions, we find the scalar discriminant function which best discriminates between the populations. The goals are two-fold: first, to construct a discriminant function which can accurately and reliably classify subjects via the image data. Second, the best discriminant allows us to see which features in the images distinguish between the populations; these features can guide us to finding characteristic differences between the two groups even if these differences are not sufficient to perform classification. We apply our method to mid-sagittal MRI sections of the corpus callosum from 34 males and 52 females. While we are not certain of the ability of the derived discriminant function to perform sex classification, we find that regions in the anterior of the corpus callosum do appear to be more important for the discriminant function than other regions. This indicates there may be significant differences in the relative size of the splenium in males and females, as has been reported elsewhere. More notably, we applied previous methods which support this view on our larger data set, but found that these methods no longer show statistically significant differences between the male and female splenium.

  7. Development of PET/MRI with insertable PET for simultaneous PET and MR imaging of human brain

    SciTech Connect

    Jung, Jin Ho; Choi, Yong Jung, Jiwoong; Kim, Sangsu; Lim, Hyun Keong; Im, Ki Chun; Oh, Chang Hyun; Park, Hyun-wook; Kim, Kyung Min; Kim, Jong Guk

    2015-05-15

    Purpose: The purpose of this study was to develop a dual-modality positron emission tomography (PET)/magnetic resonance imaging (MRI) with insertable PET for simultaneous PET and MR imaging of the human brain. Methods: The PET detector block was composed of a 4 × 4 matrix of detector modules, each consisting of a 4 × 4 array LYSO coupled to a 4 × 4 Geiger-mode avalanche photodiode (GAPD) array. The PET insert consisted of 18 detector blocks, circularly mounted on a custom-made plastic base to form a ring with an inner diameter of 390 mm and axial length of 60 mm. The PET gantry was shielded with gold-plated conductive fabric tapes with a thickness of 0.1 mm. The charge signals of PET detector transferred via 4 m long flat cables were fed into the position decoder circuit. The flat cables were shielded with a mesh-type aluminum sheet with a thickness of 0.24 mm. The position decoder circuit and field programmable gate array-embedded DAQ modules were enclosed in an aluminum box with a thickness of 10 mm and located at the rear of the MR bore inside the MRI room. A 3-T human MRI system with a Larmor frequency of 123.7 MHz and inner bore diameter of 60 cm was used as the PET/MRI hybrid system. A custom-made radio frequency (RF) coil with an inner diameter of 25 cm was fabricated. The PET was positioned between gradient and the RF coils. PET performance was measured outside and inside the MRI scanner using echo planar imaging, spin echo, turbo spin echo, and gradient echo sequences. MRI performance was also evaluated with and without the PET insert. The stability of the newly developed PET insert was evaluated and simultaneous PET and MR images of a brain phantom were acquired. Results: No significant degradation of the PET performance caused by MR was observed when the PET was operated using various MR imaging sequences. The signal-to-noise ratio of MR images was slightly degraded due to the PET insert installed inside the MR bore while the homogeneity was

  8. In-Vivo Imaging Of Transplanted Human Hepatic Stem Cells: Negative Contrast Labeling And 7t Micro-MRI Tracking

    DTIC Science & Technology

    2004-12-01

    The goals of the current study are to develop effective procedures for labeling stem cells with contrast agents for magnetic resonance imaging (MRI...ms, 2 averages) were obtained. For the fixed whole mouse experiments, a 4.0 cm-diameter birdcage RF coil was used, and interleaved multislice...stem cells, EpCAM+ cells, were labeled to induce magnetic resonance imaging contrast by either magnetodendrimers or a novel microbead-antibody

  9. Magnetic resonance imaging (MRI) of a cookie in comparison with time-lapse photographic analysis (TLPA) during baking process.

    PubMed

    Hong, S W; Yan, Z Y; Otterburn, M S; McCarthy, M J

    1996-01-01

    Magnetic Resonance Imaging (MRI) has been used to study the baking of a cookie. The structural and dynamic changes occurring during baking have been monitored, including changes in the internal moisture saturations and distribution. The images reveal the moisture distribution is initially uniform, and during baking a gradient in moisture develops from the interior to the edge. Changes in physical dimensions calculated from the data are consistent with those obtained from time-lapsed photography.

  10. MRI technique for the snapshot imaging of quantitative velocity maps using RARE

    NASA Astrophysics Data System (ADS)

    Shiko, G.; Sederman, A. J.; Gladden, L. F.

    2012-03-01

    A quantitative PGSE-RARE pulse sequence was developed and successfully applied to the in situ dissolution of two pharmaceutical formulations dissolving over a range of timescales. The new technique was chosen over other existing fast velocity imaging techniques because it is T2 weighted, not T2∗ weighted, and is, therefore, robust for imaging time-varying interfaces and flow in magnetically heterogeneous systems. The complex signal was preserved intact by separating odd and even echoes to obtain two phase maps which are then averaged in post-processing. Initially, the validity of the technique was shown when imaging laminar flow in a pipe. Subsequently, the dissolution of two drugs was followed in situ, where the technique enables the imaging and quantification of changes in the form of the tablet and the flow field surrounding it at high spatial and temporal resolution. First, the complete 3D velocity field around an eroding salicylic acid tablet was acquired at a resolution of 98 × 49 μm2, within 20 min, and monitored over ˜13 h. The tablet was observed to experience a heterogeneous flow field and, hence a heterogeneous shear field, which resulted in the non-symmetric erosion of the tablet. Second, the dissolution of a fast dissolving immediate release tablet was followed using one-shot 2D velocity images acquired every 5.2 s at a resolution of 390 × 390 μm2. The quantitative nature of the technique and fast acquisition times provided invaluable information on the dissolution behaviour of this tablet, which had not been attainable previously with conventional quantitative MRI techniques.

  11. Statistical modeling and MAP estimation for body fat quantification with MRI ratio imaging

    NASA Astrophysics Data System (ADS)

    Wong, Wilbur C. K.; Johnson, David H.; Wilson, David L.

    2008-03-01

    We are developing small animal imaging techniques to characterize the kinetics of lipid accumulation/reduction of fat depots in response to genetic/dietary factors associated with obesity and metabolic syndromes. Recently, we developed an MR ratio imaging technique that approximately yields lipid/{lipid + water}. In this work, we develop a statistical model for the ratio distribution that explicitly includes a partial volume (PV) fraction of fat and a mixture of a Rician and multiple Gaussians. Monte Carlo hypothesis testing showed that our model was valid over a wide range of coefficient of variation of the denominator distribution (c.v.: 0-0:20) and correlation coefficient among the numerator and denominator (ρ 0-0.95), which cover the typical values that we found in MRI data sets (c.v.: 0:027-0:063, ρ: 0:50-0:75). Then a maximum a posteriori (MAP) estimate for the fat percentage per voxel is proposed. Using a digital phantom with many PV voxels, we found that ratio values were not linearly related to PV fat content and that our method accurately described the histogram. In addition, the new method estimated the ground truth within +1.6% vs. +43% for an approach using an uncorrected ratio image, when we simply threshold the ratio image. On the six genetically obese rat data sets, the MAP estimate gave total fat volumes of 279 +/- 45mL, values 21% smaller than those from the uncorrected ratio images, principally due to the non-linear PV effect. We conclude that our algorithm can increase the accuracy of fat volume quantification even in regions having many PV voxels, e.g. ectopic fat depots.

  12. Ulcerated Radiodermatitis Induced after Fluoroscopically Guided Stent Implantation Angioplasty

    PubMed Central

    Herz-Ruelas, Maira Elizabeth; Gómez-Flores, Minerva; Moxica-del Angel, Joaquín; Miranda-Maldonado, Ivett; Gutiérrez-Villarreal, Ilse Marilú; Villarreal-Rodríguez, Adriana Orelia

    2014-01-01

    Cases of radiation-induced skin injury after fluoroscopically guided procedures have been reported since 1996, though the majority of them have been published in Radiology and Cardiology literature, less frequently in Dermatology journals. Chronic radiation dermatitis induced by fluoroscopy can be difficult to diagnose; a high grade of suspicion is required. We report a case of an obese 46-year-old man with hypertension, dyslipidemia, and severe coronary artery disease. He developed a pruritic and painful atrophic ulcerated skin plaque over his left scapula, six months after fluoroscopically guided stent implantation angioplasty. The diagnosis of radiodermatitis was confirmed histologically. We report this case to emphasize the importance of recognizing fluoroscopy as a cause of radiation dermatitis. A good clinical follow-up at regular intervals is important after long and complicated procedures, since the most prevalent factor for injury is long exposure time. PMID:25276441

  13. Measurement of hyoid and laryngeal displacement in video fluoroscopic swallowing studies: variability, reliability, and measurement error.

    PubMed

    Sia, Isaac; Carvajal, Pamela; Carnaby-Mann, Giselle D; Crary, Michael A

    2012-06-01

    Video fluoroscopy is commonly used in the study of swallowing kinematics. However, various procedures used in linear measurements obtained from video fluoroscopy may contribute to increased variability or measurement error. This study evaluated the influence of calibration referent and image rotation on measurement variability for hyoid and laryngeal displacement during swallowing. Inter- and intrarater reliabilities were also estimated for hyoid and laryngeal displacement measurements across conditions. The use of different calibration referents did not contribute significantly to variability in measures of hyoid and laryngeal displacement but image rotation affected horizontal measures for both structures. Inter- and intrarater reliabilities were high. Using the 95% confidence interval as the error index, measurement error was estimated to range from 2.48 to 3.06 mm. These results address procedural decisions for measuring hyoid and laryngeal displacement in video fluoroscopic swallowing studies.

  14. An open-access, very-low-field MRI system for posture-dependent 3He human lung imaging

    NASA Astrophysics Data System (ADS)

    Tsai, L. L.; Mair, R. W.; Rosen, M. S.; Patz, S.; Walsworth, R. L.

    2008-08-01

    We describe the design and operation of an open-access, very-low-field, magnetic resonance imaging (MRI) system for in vivo hyperpolarized 3He imaging of the human lungs. This system permits the study of lung function in both horizontal and upright postures, a capability with important implications in pulmonary physiology and clinical medicine, including asthma and obesity. The imager uses a bi-planar B0 coil design that produces an optimized 65 G (6.5 mT) magnetic field for 3He MRI at 210 kHz. Three sets of bi-planar coils produce the x, y, and z magnetic field gradients while providing a 79-cm inter-coil gap for the imaging subject. We use solenoidal Q-spoiled RF coils for operation at low frequencies, and are able to exploit insignificant sample loading to allow for pre-tuning/matching schemes and for accurate pre-calibration of flip angles. We obtain sufficient SNR to acquire 2D 3He images with up to 2.8 mm resolution, and present initial 2D and 3D 3He images of human lungs in both supine and upright orientations. 1H MRI can also be performed for diagnostic and calibration reasons.

  15. An Open-Access, Very-Low-Field MRI System for Posture-Dependent 3He Human Lung Imaging

    PubMed Central

    Tsai, L. L.; Mair, R. W.; Rosen, M. S.; Patz, S.; Walsworth, R. L.

    2008-01-01

    We describe the design and operation of an open-access, very-low-field, magnetic resonance imaging (MRI) system for in-vivo hyperpolarized 3He imaging of the human lungs. This system permits the study of lung function in both horizontal and upright postures, a capability with important implications in pulmonary physiology and clinical medicine, including asthma and obesity. The imager uses a bi-planar B0 coil design that produces an optimized 65 G (6.5 mT) magnetic field for 3He MRI at 210 kHz. Three sets of bi-planar coils produce the x, y, and z magnetic field gradients while providing a 79-cm inter-coil gap for the imaging subject. We use solenoidal Q-spoiled RF coils for operation at low frequencies, and are able to exploit insignificant sample loading to allow for pre-tuning/matching schemes and for accurate pre-calibration of flip angles. We obtain sufficient SNR to acquire 2D 3He images with up to 2.8 mm resolution, and present initial 2D and 3D 3He images of human lungs in both supine and upright orientations. 1H MRI can also be performed for diagnostic and calibration reasons. PMID:18550402

  16. A Prototype Micro-Angiographic Fluoroscope and Its Application in Animal Studies

    PubMed Central

    Wu, Ye; Rudin, Stephen; Bednarek, Daniel R.

    2011-01-01

    In order to satisfy the high resolution (3 to 10 cycles/mm) imaging requirements in neurovascular image-guided interventional (IGI) procedures, a micro-angiographic fluoroscope (MAF) is being developed to enable both rapid sequence angiography (15 fps) at high exposure levels (hundreds of μR/frame) as well as fluoroscopy at high frame rates (30 fps) and low exposure levels (5 to 20 μR/frame). The prototype MAF consists of a 350-μm-thick CsI(Tl) scintillator coupled by a 2:1 fiber-optical taper to an 18 mm diameter variable-gain light image intensifier with two-stage microchannel plate (MCP) viewed by a 12-bit, 1024x1024, 30 fps CCD camera with digital interface board. The optical set-up enables variation of effective pixel-size from 31 to 50 micron. The first frame lag of the MAF in fluoroscopic 30 fps mode (2:1 binning) was less than 0.8% at exposures of 5-23 μR/frame. MTF, NPS, and DQE in angiographic mode were measured for IEC standard spectrum RQA 5. At spatial frequencies of 4 and 10 cycles/mm the MTF was 14% and 1.5%, and the DQE was 12% and 1.2%, respectively, while the DQE(0) was 60%. Acquisition software was developed to acquire 15 fps angiography and 30 fps fluoroscopy for real-time dark field and flat field correction or real-time roadmapping. Images obtained with the MAF in small animal IGI procedures are demonstrated. The linearity versus x-ray intensity and MCP working range effects has been studied. We plan to expand the current 3.6 cm diameter field of view to 6 cm in the next model of the MAF. PMID:21311727

  17. Magnetic resonance imaging (MRI) and prognostication in neonatal hypoxic-ischemic injury: a vignette-based study of Canadian specialty physicians.

    PubMed

    Bell, Emily; Rasmussen, Lisa Anne; Mazer, Barbara; Shevell, Michael; Miller, Steven P; Synnes, Anne; Yager, Jerome Y; Majnemer, Annette; Muhajarine, Nazeem; Chouinard, Isabelle; Racine, Eric

    2015-02-01

    Magnetic resonance imaging (MRI) could improve prognostication in neonatal brain injury; however, factors beyond technical or scientific refinement may impact its use and interpretation. We surveyed Canadian neonatologists and pediatric neurologists using general and vignette-based questions about the use of MRI for prognostication in neonates with hypoxic-ischemic injury. There was inter- and intra-vignette variability in prognosis and in ratings about the usefulness of MRI. Severity of predicted outcome correlated with certainty about the outcome. A majority of physicians endorsed using MRI results in discussing prognosis with families, and most suggested that MRI results contribute to end-of-life decisions. Participating neonatologists, when compared to participating pediatric neurologists, had significantly less confidence in the interpretation of MRI by colleagues in neurology and radiology. Further investigation is needed to understand the complexity of MRI and of its application. Potential gaps relative to our understanding of the ethical importance of these findings should be addressed.

  18. Validating an image-based fNIRS approach with fMRI and a working memory task.

    PubMed

    Wijeakumar, Sobanawartiny; Huppert, Theodore J; Magnotta, Vincent A; Buss, Aaron T; Spencer, John P

    2017-02-15

    In the current study, we extend a previous methodological pipeline by adding a novel image reconstruction approach to move functional near-infrared (fNIRS) signals from channel-space on the surface of the head to voxel-space within the brain volume. We validate this methodology by comparing voxel-wise fNIRS results to functional magnetic resonance imaging (fMRI) results from a visual working memory (VWM) task using two approaches. In the first approach, significant voxel-wise correlations were observed between fNIRS and fMRI measures for all experimental conditions across brain regions in the fronto-parieto-temporal cortices. In the second approach, we conducted separate multi-factorial ANOVAs on fNIRS and fMRI measures and then examined the correspondence between main and interaction effects within common regions of interest. Both fMRI and fNIRS showed similar trends in activation within the VWM network when the number of items held in working memory increases. These results validate the image-based fNIRS approach.

  19. A comparison study between the saturation-recovery-T1 and CASL MRI methods for quantitative CBF imaging.

    PubMed

    Wang, Xiao; Zhu, Xiao-Hong; Zhang, Yi; Divani, Afshin A; Murphy, Amanda J; Chen, Wei

    2017-04-01

    The saturation-recovery (SR)-T1 MRI method for quantitatively imaging cerebral blood flow (CBF) change (ΔCBF) concurrently with the blood oxygenation level dependence (BOLD) alteration has been recently developed and validated by simultaneous measurement of relative CBF change using laser Doppler flowmetry (LDF) in rats at 9.4T. In this study, ΔCBF induced by mildly transient hypercapnia and measured by the SR-T1 MRI method was rigorously compared with an established perfusion MRI method-continuous arterial spin labeling (CASL) approach in normal and preclinical middle cerebral artery occlusion (MCAo) rat models. The results show an excellent agreement between ΔCBF values measured with these two imaging methods. Moreover, the intrinsic longitudinal relaxation rate (R1(int)) was experimentally determined in vivo in normal rat brains at 9.4T by comparing two independent measures of the apparent longitudinal relaxation rate (R1(app)) and CBF measured by the CSAL approach across a wide range of perfusion. In turn, the R1(int) constant can be employed to calculate the CBF value based on the R1(app) measurement in healthy brain. This comparison study validates the fundamental relationship for linking brain tissue water R1(app) and cerebral perfusion, demonstrates the feasibility of imaging and quantifying both CBF and its change using the SR-T1 MRI method in vivo.

  20. Validation of fast diffusion kurtosis MRI for imaging acute ischemia in a rodent model of stroke

    PubMed Central

    Sun, Phillip Zhe; Wang, Yu; Mandeville, Emiri; Chan, Suk-Tak; Lo, Eng H; Ji, Xunming

    2014-01-01

    Diffusion-weighted imaging (DWI) captures ischemic tissue that is likely to infarct, and has become one of the most widely used acute stroke imaging techniques. Diffusion kurtosis imaging (DKI) has lately been postulated as a complementary MRI method to stratify the heterogeneously damaged DWI lesion. However, the conventional DKI acquisition time is relatively long, limiting its use in the acute stroke setting. Recently, Hansen et al. proposed a fast kurtosis mapping method and demonstrated it in fixed brains and control subjects. The fast DKI approach provides mean diffusion and kurtosis measurements under substantially reduced scan time, making it amenable to acute stroke imaging. Because it is not practical to obtain and compare different means of DKI to test whether the fast DKI method can reliably detect diffusion and kurtosis lesions in acute stroke patients, our study investigated its diagnostic value using an animal model of acute stroke, a critical step before fast DKI acquisition can be routinely applied in the acute stroke setting. We found significant correlation, per voxel, between the diffusion and kurtosis coefficients measured using the fast and conventional DKI protocols. In acute stroke rats, both DKI methods yielded diffusion and kurtosis lesions that were in good agreement. Importantly, substantial kurtosis/diffusion lesion mismatch was observed using the conventional (26±13%, P<0.01) and fast DKI methods (23±8%, P<0.01). In addition, regression analysis showed that the kurtosis/diffusion lesion mismatch obtained using conventional and fast DKI methods were substantially correlated (R2=0.57, P=0.02). Our results confirmed that the recently proposed fast DKI method is capable of capturing heterogeneous diffusion and kurtosis lesions in acute ischemic stroke, and thus is suitable for translational applications in the acute stroke clinical setting. PMID:25208309

  1. Validation of fast diffusion kurtosis MRI for imaging acute ischemia in a rodent model of stroke.

    PubMed

    Sun, Phillip Zhe; Wang, Yu; Mandeville, Emiri; Chan, Suk-Tak; Lo, Eng H; Ji, Xunming

    2014-11-01

    Diffusion-weighted imaging (DWI) captures ischemic tissue that is likely to infarct, and has become one of the most widely used acute stroke imaging techniques. Diffusion kurtosis imaging (DKI) has lately been postulated as a complementary MRI method to stratify the heterogeneously damaged DWI lesion. However, the conventional DKI acquisition time is relatively long, limiting its use in the acute stroke setting. Recently, a fast kurtosis mapping method has been demonstrated in fixed brains and control subjects. The fast DKI approach provides mean diffusion and kurtosis measurements under substantially reduced scan time, making it amenable to acute stroke imaging. Because it is not practical to obtain and compare different means of DKI to test whether the fast DKI method can reliably detect diffusion and kurtosis lesions in acute stroke patients, our study investigated its diagnostic value using an animal model of acute stroke, a critical step before fast DKI acquisition can be routinely applied in the acute stroke setting. We found significant correlation, per voxel, between the diffusion and kurtosis coefficients measured using the fast and conventional DKI protocols. In acute stroke rats, the two DKI methods yielded diffusion and kurtosis lesions that were in good agreement. Importantly, substantial kurtosis-diffusion lesion mismatch was observed using the conventional (26 ± 13%, P < 0.01) and fast DKI methods (23 ± 8%, P < 0.01). In addition, regression analysis showed that the kurtosis-diffusion lesion mismatches obtained using conventional and fast DKI methods were substantially correlated (R(2) = 0.57, P = 0.02). Our results confirmed that the recently proposed fast DKI method is capable of capturing heterogeneous diffusion and kurtosis lesions in acute ischemic stroke, and thus is suitable for translational applications in the acute stroke clinical setting.

  2. Feasibility of Imaging Tissue Electrical Conductivity by Switching Field Gradients with MRI.

    PubMed

    Gibbs, Eric; Liu, Chunlei

    2015-12-01

    Tissue conductivity is a biophysical marker of tissue structure and physiology. Present methods of measuring tissue conductivity are limited. Electrical impedance tomography, and magnetic resonance electrical impedance tomography rely on passing external current through the object being imaged, which prevents its use in most human imaging. Recently, the RF field used for MR excitation has been used to non-invasively measure tissue conductivity. This technique is promising, but conductivity at higher frequencies is less sensitive to tissue structure. Measuring tissue conductivity non-invasively at low frequencies remains elusive. It has been proposed that eddy currents generated during the rise and decay of gradient pulses could act as a current source to map low-frequency conductivity. This work centers on a gradient echo pulse sequence that uses large gradients prior to excitation to create eddy currents. The electric and magnetic fields during a gradient pulse are simulated by a finite-difference time-domain simulation. The sequence is also tested with a phantom and an animal MRI scanner equipped with gradients of high gradient strengths and slew rate. The simulation demonstrates that eddy currents in materials with conductivity similar to biological tissue decay with a half-life on the order of nanoseconds and any eddy currents generated prior to excitation decay completely before influencing the RF signal. Gradient-induced eddy currents can influence phase accumulation after excitation but the effect is too small to image. The animal scanner images show no measurable phase accumulation. Measuring low-frequency conductivity by gradient-induced eddy currents is presently unfeasible.

  3. Feasibility of Imaging Tissue Electrical Conductivity by Switching Field Gradients with MRI

    PubMed Central

    Gibbs, Eric; Liu, Chunlei

    2016-01-01

    Tissue conductivity is a biophysical marker of tissue structure and physiology. Present methods of measuring tissue conductivity are limited. Electrical impedance tomography, and magnetic resonance electrical impedance tomography rely on passing external current through the object being imaged, which prevents its use in most human imaging. Recently, the RF field used for MR excitation has been used to non-invasively measure tissue conductivity. This technique is promising, but conductivity at higher frequencies is less sensitive to tissue structure. Measuring tissue conductivity non-invasively at low frequencies remains elusive. It has been proposed that eddy currents generated during the rise and decay of gradient pulses could act as a current source to map low-frequency conductivity. This work centers on a gradient echo pulse sequence that uses large gradients prior to excitation to create eddy currents. The electric and magnetic fields during a gradient pulse are simulated by a finite-difference time-domain simulation. The sequence is also tested with a phantom and an animal MRI scanner equipped with gradients of high gradient strengths and slew rate. The simulation demonstrates that eddy currents in materials with conductivity similar to biological tissue decay with a half-life on the order of nanoseconds and any eddy currents generated prior to excitation decay completely before influencing the RF signal. Gradient-induced eddy currents can influence phase accumulation after excitation but the effect is too small to image. The animal scanner images show no measurable phase accumulation. Measuring low-frequency conductivity by gradient-induced eddy currents is presently unfeasible. PMID:26844302

  4. Magnetic resonance imaging (MRI) and pathophysiology of the rat kidney in streptozotocin-induced diabetes

    SciTech Connect

    Lohr, J.; Mazurchuk, R.J.; Acara, M.A.; Nickerson, P.A.; Fiel, R.J. )

    1991-01-01

    Proton magnetic resonance imaging was performed on rats before induction of diabetes with streptozotocin (STZ) and at 2 and 12 days postinduction. Images revealed an increase in maximal longitudinal and axial dimensions of the kidneys at 2 days and a further increase at 12 days. Similarly, an increase in the size of the remaining kidney was seen in a rat which underwent uninephrectomy as a positive control. Two major differences were observed between the kidney undergoing compensatory hypertrophy and those developing diabetic nephropathy: (i) Expansion of the renal vasculature was seen only in images of the diabetic rat; (ii) A loss in conspicuity of the normal corticomedullary junction was seen in the T2-weighted images of the diabetic rat but not in the uninephrectomized rat. Histologic examination revealed that the medulla increased to a size greater than the cortex during diabetic nephropathy whereas the medullary volume was less than that of the cortex during compensatory hypertrophy. In vitro T1 relaxation times in cortex, outer medulla and inner medulla of kidneys from control rats were measured and compared with the same respective regions in diabetic rats. When these values were correlated with tissue water content, a linear increase in relaxation rate versus percent water content from cortex to inner medulla was found in the control kidneys, but this correlation was absent in diabetic nephropathy. These studies demonstrate that MRI is an effective noninvasive tool for studying the course of renal hypertrophy and hydration changes in the development of renal disease in STZ-induced diabetes in the rat.

  5. Combining MRI and VEP imaging to isolate the temporal response of visual cortical areas

    NASA Astrophysics Data System (ADS)

    Carney, Thom; Ales, Justin; Klein, Stanley A.

    2008-02-01

    The human brain has well over 30 cortical areas devoted to visual processing. Classical neuro-anatomical as well as fMRI studies have demonstrated that early visual areas have a retinotopic organization whereby adjacent locations in visual space are represented in adjacent areas of cortex within a visual area. At the 2006 Electronic Imaging meeting we presented a method using sprite graphics to obtain high resolution retinotopic visual evoked potential responses using multi-focal m-sequence technology (mfVEP). We have used this method to record mfVEPs from up to 192 non overlapping checkerboard stimulus patches scaled such that each patch activates about 12 mm2 of cortex in area V1 and even less in V2. This dense coverage enables us to incorporate cortical folding constraints, given by anatomical MRI and fMRI results from the same subject, to isolate the V1 and V2 temporal responses. Moreover, the method offers a simple means of validating the accuracy of the extracted V1 and V2 time functions by comparing the results between left and right hemispheres that have unique folding patterns and are processed independently. Previous VEP studies have been contradictory as to which area responds first to visual stimuli. This new method accurately separates the signals from the two areas and demonstrates that both respond with essentially the same latency. A new method is introduced which describes better ways to isolate cortical areas using an empirically determined forward model. The method includes a novel steady state mfVEP and complex SVD techniques. In addition, this evolving technology is put to use examining how stimulus attributes differentially impact the response in different cortical areas, in particular how fast nonlinear contrast processing occurs. This question is examined using both state triggered kernel estimation (STKE) and m-sequence "conditioned kernels". The analysis indicates different contrast gain control processes in areas V1 and V2. Finally we

  6. Imaging of Her2-targeted magnetic nanoparticles for breast cancer detection: comparison of SQUID-detected magnetic relaxometry and MRI.

    PubMed

    Adolphi, Natalie L; Butler, Kimberly S; Lovato, Debbie M; Tessier, T E; Trujillo, Jason E; Hathaway, Helen J; Fegan, Danielle L; Monson, Todd C; Stevens, Tyler E; Huber, Dale L; Ramu, Jaivijay; Milne, Michelle L; Altobelli, Stephen A; Bryant, Howard C; Larson, Richard S; Flynn, Edward R

    2012-01-01

    Both magnetic relaxometry and magnetic resonance imaging (MRI) can be used to detect and locate targeted magnetic nanoparticles, noninvasively and without ionizing radiation. Magnetic relaxometry offers advantages in terms of its specificity (only nanoparticles are detected) and the linear dependence of the relaxometry signal on the number of nanoparticles present. In this study, detection of single-core iron oxide nanoparticles by superconducting quantum interference device (SQUID)-detected magnetic relaxometry and standard 4.7 T MRI are compared. The nanoparticles were conjugated to a Her2 monoclonal antibody and targeted to Her2-expressing MCF7/Her2-18 (breast cancer cells); binding of the nanoparticles to the cells was assessed by magnetic relaxometry and iron assay. The same nanoparticle-labeled cells, serially diluted, were used to assess the detection limits and MR relaxivities. The detection limit of magnetic relaxometry was 125 000 nanoparticle-labeled cells at 3 cm from the SQUID sensors. T(2)-weighted MRI yielded a detection limit of 15 600 cells in a 150 µl volume, with r(1) = 1.1 mm(-1) s(-1) and r(2) = 166 mm(-1) s(-1). Her2-targeted nanoparticles were directly injected into xenograft MCF7/Her2-18 tumors in nude mice, and magnetic relaxometry imaging and 4.7 T MRI were performed, enabling direct comparison of the two techniques. Co-registration of relaxometry images and MRI of mice resulted in good agreement. A method for obtaining accurate quantification of microgram quantities of iron in the tumors and liver by relaxometry was also demonstrated. These results demonstrate the potential of SQUID-detected magnetic relaxometry imaging for the specific detection of breast cancer and the monitoring of magnetic nanoparticle-based therapies.

  7. Imaging of Her2-Targeted Magnetic Nanoparticles for Breast Cancer Detection: Comparison of SQUID-detected Magnetic Relaxometry and MRI

    PubMed Central

    Adolphi, Natalie L.; Butler, Kimberly S.; Lovato, Debbie M.; Tessier, T. E.; Trujillo, Jason E.; Hathaway, Helen J.; Fegan, Danielle L.; Monson, Todd C.; Stevens, Tyler E.; Huber, Dale L.; Ramu, Jaivijay; Milne, Michelle L.; Altobelli, Stephen A.; Bryant, Howard C.; Larson, Richard S.; Flynn, Edward R.

    2013-01-01

    Both magnetic relaxometry and magnetic resonance imaging (MRI) can be used to detect and locate targeted magnetic nanoparticles, non-invasively and without ionizing radiation. Magnetic relaxometry offers advantages in terms of its specificity (only nanoparticles are detected) and the linear dependence of the relaxometry signal on the number of nanoparticles present. In this study, detection of single-core iron oxide nanoparticles by Superconducting Quantum Interference Device (SQUID)-detected magnetic relaxometry and standard 4.7 T MRI are compared. The nanoparticles were conjugated to a Her2 monoclonal antibody and targeted to Her2-expressing MCF7/Her2-18 breast cancer cells); binding of the nanoparticles to the cells was assessed by magnetic relaxometry and iron assay. The same nanoparticle-labeled cells, serially diluted, were used to assess the detection limits and MR relaxivities. The detection limit of magnetic relaxometry was 125,000 nanoparticle-labeled cells at 3 cm from the SQUID sensors. T2-weighted MRI yielded a detection limit of 15,600 cells in a 150 μl volume, with r1 = 1.1 mM−1s−1 and r2 = 166 mM−1s−1. Her2-targeted nanoparticles were directly injected into xenograft MCF7/Her2-18 tumors in nude mice, and magnetic relaxometry imaging and 4.7 T MRI were performed, enabling direct comparison of the two techniques. Co-registration of relaxometry images and MRI of mice resulted in good agreement. A method for obtaining accurate quantification of microgram quantities of iron in the tumors and liver by relaxometry was also demonstrated. These results demonstrate the potential of SQUID-detected magnetic relaxometry imaging for the specific detection of breast cancer and the monitoring of magnetic nanoparticle-based therapies. PMID:22539401

  8. Imaging cognition II: An empirical review of 275 PET and fMRI studies.

    PubMed

    Cabeza, R; Nyberg, L

    2000-01-01

    Positron emission tomography (PET) and functional magnetic resonance imaging (fMRI) have been extensively used to explore the functional neuroanatomy of cognitive functions. Here we review 275 PET and fMRI studies of attention (sustained, selective, Stroop, orientation, divided), perception (object, face, space/motion, smell), imagery (object, space/motion), language (written/spoken word recognition, spoken/no spoken response), working memory (verbal/numeric, object, spatial, problem solving), semantic memory retrieval (categorization, generation), episodic memory encoding (verbal, object, spatial), episodic memory retrieval (verbal, nonverbal, success, effort, mode, context), priming (perceptual, conceptual), and procedural memory (conditioning, motor, and nonmotor skill learning). To identify consistent activation patterns associated with these cognitive operations, data from 412 contrasts were summarized at the level of cortical Brodmann's areas, insula, thalamus, medial-temporal lobe (including hippocampus), basal ganglia, and cerebellum. For perception and imagery, activation patterns included primary and secondary regions in the dorsal and ventral pathways. For attention and working memory, activations were usually found in prefrontal and parietal regions. For language and semantic memory retrieval, typical regions included left prefrontal and temporal regions. For episodic memory encoding, consistently activated regions included left prefrontal and medial temporal regions. For episodic memory retrieval, activation patterns included prefrontal, medial temporal, and posterior midline regions. For priming, deactivations in prefrontal (conceptual) or extrastriate (perceptual) regions were consistently seen. For procedural memory, activations were found in motor as well as in non-motor brain areas. Analysis of regional activations across cognitive domains suggested that several brain regions, including the cerebellum, are engaged by a variety of cognitive

  9. 11C-Acetate PET/CT Imaging in Localized Prostate Cancer: A study with MRI and Histopathologic Correlation

    PubMed Central

    Mena, Esther; Turkbey, Baris; Mani, Haresh; Adler, Stephen; Valera, Vladimir A.; Bernardo, Marcelino; Shah, Vijay; Pohida, Thomas; McKinney, Yolanda; Kwarteng, Gideon; Daar, Dagane; Lindenberg, Maria L.; Eclarinal, Philip; Wade, Revia; Linehan, W. Marston; Merino, Maria J.; Pinto, Peter A.; Choyke, Peter L.; Kurdziel, Karen A.

    2012-01-01

    This work characterizes the uptake of 11C-Acetate in prostate cancer (PCa), benign prostate hyperplasia (BPH) and normal prostate tissue in comparison with multi-parametric MRI, whole mount histopathology and clinical markers, to evaluate its potential utility for delineating intra-prostatic tumors in a population of patients with localized PCa. METHODS 39 men with presumed localized PCa underwent dynamic/static abdomen-pelvic 11C-Acetate PET/CT for 30-minutes and 3T multi-parametric (MP) MRI prior to prostatectomy. PET/CT images were registered to MRI using pelvic bones for initial rotation-translation, followed by manual adjustments to account for prostate motion and deformation from the MRI endorectal coil. Whole-mount pathology specimens were sectioned using an MRI-based patient specific mold resulting in improved registration between the MRI, PET and pathology. 11C-Acetate PET standardized uptake values were compared with MP-MRI and pathology. RESULTS 11C-Acetate uptake was rapid but reversible, peaking at 3–5 minutes post-injection and reaching a relative plateau at ~10 minutes. The average SUVmax(10–12min) of tumors was significantly higher than that of normal prostate tissue (4.4±2.05, range 1.8–9.2 vs. 2.1±0.94, range 0.7–3.4; p<0.001); however it was not significantly different from benign prostatic hyperplasia (4.8±2.01; range 1.8–8.8). A sector-based comparison with histopathology, including all tumors > 0.5 cm, revealed a sensitivity and specificity of 61.6 % and 80.0 % for 11C-Acetate PET/CT, and 82.3% and 95.1% for MRI, respectively. Considering only tumors >0.9 cm the 11C-Acetate accuracy was comparable to that of MRI. In a small cohort (n=9), 11C-Acetate uptake was independent of fatty acid synthase expression based on immunohistochemistry. CONCLUSION 11C-Acetate PET/CT demonstrates higher uptake in tumor foci than normal prostate tissue; however 11C-Acetate uptake in tumors is similar to BPH nodules. While 11C-Acetate PET/CT is not

  10. 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)).

  11. Magnetic Resonance Imaging (MRI) Analysis of Fibroid Location in Women Achieving Pregnancy After Uterine Artery Embolization

    SciTech Connect

    Walker, Woodruff J.; Bratby, Mark John

    2007-09-15

    The purpose of this study was to evaluate the fibroid morphology in a cohort of women achieving pregnancy following treatment with uterine artery embolization (UAE) for symptomatic uterine fibroids. A retrospective review of magnetic resonance imaging (MRI) of the uterus was performed to assess pre-embolization fibroid morphology. Data were collected on fibroid size, type, and number and included analysis of follow-up imaging to assess response. There have been 67 pregnancies in 51 women, with 40 live births. Intramural fibroids were seen in 62.7% of the women (32/48). Of these the fibroids were multiple in 16. A further 12 women had submucosal fibroids, with equal numbers of types 1 and 2. Two of these women had coexistent intramural fibroids. In six women the fibroids could not be individually delineated and formed a complex mass. All subtypes of fibroid were represented in those subgroups of women achieving a live birth versus those who did not. These results demonstrate that the location of uterine fibroids did not adversely affect subsequent pregnancy in the patient population investigated. Although this is only a small qualitative study, it does suggest that all types of fibroids treated with UAE have the potential for future fertility.

  12. Bing-Neel Syndrome Case Report: A Previously Undocumented IgG Variant with MRI, PET/CT, and PET/MRI Imaging.

    PubMed

    Halperin, Daniel; Hallam, Simon; Haroon, Athar; Butler, Tom; Agrawal, Samir

    2016-01-01

    Waldenstrom's macroglobulinaemia is the most commonly reported subtype of lymphoplasmacytic lymphoma (LPL); it is characterised by IgM secretion. Neurological complications are common usually as a result of hyperviscosity. In rare cases, cells can infiltrate the central nervous system; this is known as Bing-Neel syndrome. We report the case of a 57-year-old male with lymphoplasmacytic lymphoma of the IgG-subtype with neurological symptoms and the consequent finding of lymphoplasmacytoid cells in his cerebrospinal fluid as well as deposits on MRI and PET-CT imaging. This is the first report of Bing-Neel syndrome in IgG-subtype LPL. We discuss the biological and radiological markers of his disease, including PET imaging, which has been minimal in this area to date.

  13. Case Report of False-Negative Diffusion-Weighted Image of Brain Magnetic Resonance Imaging (MRI) in Acute Ischemic Stroke

    PubMed Central

    Chang, Wei-Lun; Lai, Ji-Ching; Chen, Rong-Fu; Hu, Han-Hwa; Pan, Chau-Shiung

    2017-01-01

    Patient: Male, 75 Final Diagnosis: Acute ischemic stroke Symptoms: Dizziness • unsteady gait Medication: — Clinical Procedure: None Specialty: Radiology Objective: Challenging differential diagnosis Background: Acute ischemic stroke is a major cause of mortality and morbidity in Taiwan. Diffusion-weighted image (DWI) is a sensitive and common strategy used for imaging acute ischemic stroke. Case report: We present a case of a negative DWI MRI for detecting acute ischemic stroke in a clinical setting. A 75-year-old male had a DWI performed after onset of symptoms suggesting acute ischemic stroke. The initial DWI result was negative at 72 hours of presentation. The neurological symptoms of the patient persisted and DWI was repeated. After 14 days, the DWI data confirmed and demonstrated an acute ischemic stroke. The delay in DWI confirmation, from symptom onset until DWI diagnosis, was 336 hours. Conclusions: DWI may not have 100% sensitivity and accuracy in early stages of acute ischemic stroke. The time course to the development of abnormalities detected by DWI may be longer than anticipated. PMID:28111452

  14. 18F-FDG PET/CT/MRI Fusion Images Showing Cranial and Peripheral Nerve Involvement in Neurolymphomatosis

    PubMed Central

    Trevisan, Ana Carolina; Ribeiro, Fernanda Borges; Itikawa, Emerson Nobuyuki; Alexandre, Leonardo Santos; Pitella, Felipe Arriva; Santos, Antonio Carlos; Simões, Belinda Pinto; Wichert-Ana, Lauro

    2017-01-01

    We report a 56-year-old female patient with non-Hodgkin's diffuse large B cell lymphoma (NHL) who, on magnetic resonance imaging (MRI) with a T1 weighted and gadolinium-enhanced imaging, was found to have thickening and infiltration in 75% of peripheral nerves of the patient and enlargements of cranial nerves, possibly related to lymphomatous infiltration. Subsequent positron emission tomography/computed tomography (PET/CT) using 18F-labeled 2-deoxy-2-fluoro-d-glucose (18F-FDG) showed widespread active involvement of the cervical plexus, bilateral peripheral nerves, right femoral nerve, the parasellar region of the skull, and marked hypermetabolism in the left trigeminal ganglia. This case re-emphasizes that while CT and MRI provide anatomical details, 18F-FDG PET/CT images better delineate the metabolic activity of neurolymphomatosis (NL) in the peripheral and central nervous system. PMID:28242998

  15. Image-guided tissue engineering of anatomically shaped implants via MRI and micro-CT using injection molding.

    PubMed

    Ballyns, Jeffery J; Gleghorn, Jason P; Niebrzydowski, Vicki; Rawlinson, Jeremy J; Potter, Hollis G; Maher, Suzanne A; Wright, Timothy M; Bonassar, Lawrence J

    2008-07-01

    This study demonstrates for the first time the development of engineered tissues based on anatomic geometries derived from widely used medical imaging modalities such as computed tomography (CT) and magnetic resonance imaging (MRI). Computer-aided design and tissue injection molding techniques have demonstrated the ability to generate living implants of complex geometry. Due to its complex geometry, the meniscus of the knee was used as an example of this technique's capabilities. MRI and microcomputed tomography (microCT) were used to design custom-printed molds that enabled the generation of anatomically shaped constructs that retained shape throughout 8 weeks of culture. Engineered constructs showed progressive tissue formation indicated by increases in extracellular matrix content and mechanical properties. The paradigm of interfacing tissue injection molding technology can be applied to other medical imaging techniques that render 3D models of anatomy, demonstrating the potential to apply the current technique to engineering of many tissues and organs.

  16. Imaging Modalities for Assessment of Treatment Response to Nonsurgical Hepatocellular Carcinoma Therapy: Contrast-Enhanced US, CT, and MRI.

    PubMed

    Minami, Yasunori; Kudo, Masatoshi

    2015-03-01

    Tumor response and time to progression have been considered pivotal for surrogate assessment of treatment efficacy for patients with hepatocellular carcinoma (HCC). Recent advancements in imaging modalities such as contrast-enhanced ultrasound (US), computed tomography (CT), and magnetic resonance imaging (MRI) are playing an important role in assessing the therapeutic effects of HCC treatments. According to some HCC clinical guidelines, post-therapeutic evaluation of HCC patients is based exclusively on contrast-enhanced dynamic imaging criteria. The recommended techniques are contrast-enhanced CT or contrast-enhanced MRI. Contrast-enhanced US is employed more in the positive diagnosis of HCC than in post-therapeutic monitoring. Although contrast enhancement is an important finding on imaging, enhancement does not necessarily depict the same phenomenon across modalities. We need to become well acquainted with the characteristics of each modality, including not only contrast-enhanced CT and MRI but also contrast-enhanced US. Many nonsurgical treatment options are now available for unresectable HCC, and accurate assessment of tumor response is essential to achieve favorable outcomes. For the assessment of successful radiofrequency ablation (RFA), the achievement of a sufficient ablation margin as well the absence of tumor vascular enhancement is essential. To evaluate the response to transcatheter arterial chemoembolization (TACE), enhanced tumor shrinkage is relied on as a measure of antitumor activity. Here, we give an overview of the current status of imaging assessment of HCC response to nonsurgical treatments including RFA and TACE.

  17. Arm MRI scan

    MedlinePlus

    ... arm MRI (magnetic resonance imaging) scan uses strong magnets to create pictures of the upper and lower ... in your eyes) Because the MRI contains strong magnets, metal objects are not allowed into the room ...

  18. MRI Safety during Pregnancy

    MedlinePlus

    ... 20 to 40 minutes. top of page Contrast material For some MRI exams, a contrast material called gadolinium will need to be injected into a vein in the arm. While contrast material sometimes improves the MRI images, during pregnancy the ...

  19. The effects of orientation and attention during surround suppression of small image features: A 7 Tesla fMRI study

    PubMed Central

    Schallmo, Michael-Paul; Grant, Andrea N.; Burton, Philip C.; Olman, Cheryl A.

    2016-01-01

    Although V1 responses are driven primarily by elements within a neuron's receptive field, which subtends about 1° visual angle in parafoveal regions, previous work has shown that localized fMRI responses to visual elements reflect not only local feature encoding but also long-range pattern attributes. However, separating the response to an image feature from the response to the surrounding stimulus and studying the interactions between these two responses demands both spatial precision and signal independence, which may be challenging to attain with fMRI. The present study used 7 Tesla fMRI with 1.2-mm resolution to measure the interactions between small sinusoidal grating patches (targets) at 3° eccentricity and surrounds of various sizes and orientations to test the conditions under which localized, context-dependent fMRI responses could be predicted from either psychophysical or electrophysiological data. Targets were presented at 8%, 16%, and 32% contrast while manipulating (a) spatial extent of parallel (strongly suppressive) or orthogonal (weakly suppressive) surrounds, (b) locus of attention, (c) stimulus onset asynchrony between target and surround, and (d) blocked versus event-related design. In all experiments, the V1 fMRI signal was lower when target stimuli were flanked by parallel versus orthogonal context. Attention amplified fMRI responses to all stimuli but did not show a selective effect on central target responses or a measurable effect on orientation-dependent surround suppression. Suppression of the V1 fMRI response by parallel surrounds was stronger than predicted from psychophysics but showed a better match to previous electrophysiological reports. PMID:27565016

  20. High-Speed Real-Time Resting-State fMRI Using Multi-Slab Echo-Volumar Imaging

    PubMed Central

    Posse, Stefan; Ackley, Elena; Mutihac, Radu; Zhang, Tongsheng; Hummatov, Ruslan; Akhtari, Massoud; Chohan, Muhammad; Fisch, Bruce; Yonas, Howard

    2013-01-01

    We recently demonstrated that ultra-high-speed real-time fMRI using multi-slab echo-volumar imaging (MEVI) significantly increases sensitivity for mapping task-related activation and resting-state networks (RSNs) compared to echo-planar imaging (Posse et al., 2012). In the present study we characterize the sensitivity of MEVI for mapping RSN connectivity dynamics, comparing independent component analysis (ICA) and a novel seed-based connectivity analysis (SBCA) that combines sliding-window correlation analysis with meta-statistics. This SBCA approach is shown to minimize the effects of confounds, such as movement, and CSF and white matter signal changes, and enables real-time monitoring of RSN dynamics at time scales of tens of seconds. We demonstrate highly sensitive mapping of eloquent cortex in the vicinity of brain tumors and arterio-venous malformations, and detection of abnormal resting-state connectivity in epilepsy. In patients with motor impairment, resting-state fMRI provided focal localization of sensorimotor cortex compared with more diffuse activation in task-based fMRI. The fast acquisition speed of MEVI enabled segregation of cardiac-related signal pulsation using ICA, which revealed distinct regional differences in pulsation amplitude and waveform, elevated signal pulsation in patients with arterio-venous malformations and a trend toward reduced pulsatility in gray matter of patients compared with healthy controls. Mapping cardiac pulsation in cortical gray matter may carry important functional information that distinguishes healthy from diseased tissue vasculature. This novel fMRI methodology is particularly promising for mapping eloquent cortex in patients with neurological disease, having variable degree of cooperation in task-based fMRI. In conclusion, ultra-high-real-time speed fMRI enhances the sensitivity of mapping the dynamics of resting-state connectivity and cerebro-vascular pulsatility for clinical and neuroscience research applications

  1. Long-circulating PEGylated manganese ferrite nanoparticles for MRI-based molecular imaging

    NASA Astrophysics Data System (ADS)

    Pernia Leal, Manuel; Rivera-Fernández, Sara; Franco, Jaime M.; Pozo, David; de La Fuente, Jesús M.; García-Martín, María Luisa

    2015-01-01

    Magnetic resonance based molecular imaging has emerged as a very promising technique for early detection and treatment of a wide variety of diseases, including cancer, neurodegenerative disorders, and vascular diseases. The limited sensitivity and specificity of conventional MRI are being overcome by the development of a new generation of contrast agents, using nanotechnology approaches, with improved magnetic and biological properties. In particular, for molecular imaging, high specificity, high sensitivity, and long blood circulation times are required. Furthermore, the lack of toxicity and immunogenicity together with low-cost scalable production are also necessary to get them into the clinics. In this work, we describe a facile, robust and cost-effective ligand-exchange method to synthesize dual T1 and T2 MRI contrast agents with long circulation times. These contrast agents are based on manganese ferrite nanoparticles (MNPs) between 6 and 14 nm in size covered by a 3 kDa polyethylene glycol (PEG) shell that leads to a great stability in aqueous media with high crystallinity and magnetization values, thus retaining the magnetic properties of the uncovered MNPs. Moreover, the PEGylated MNPs have shown different relaxivities depending on their size and the magnetic field applied. Thus, the 6 nm PEGylated MNPs are characterized by a low r2/r1 ratio of 4.9 at 1.5 T, hence resulting in good dual T1 and T2 contrast agents under low magnetic fields, whereas the 14 nm MNPs behave as excellent T2 contrast agents under high magnetic fields (r2 = 335.6 mM-1 s-1). The polymer core shell of the PEGylated MNPs minimizes their cytotoxicity, and allows long blood circulation times. This combination of cellular compatibility and excellent T2 and r2/r1 values under low magnetic fields, together with long circulation times, make these nanomaterials very promising contrast agents for molecular imaging.Magnetic resonance based molecular imaging has emerged as a very promising

  2. Quantitative Myocardial Perfusion with Dynamic Contrast-Enhanced Imaging in MRI and CT: Theoretical Models and Current Implementation

    PubMed Central

    Handayani, A.; Dijkstra, H.; Prakken, N. H. J.; Slart, R. H. J. A.; Oudkerk, M.; Van Ooijen, P. M. A.; Vliegenthart, R.; Sijens, P. E.

    2016-01-01

    Technological advances in magnetic resonance imaging (MRI) and computed tomography (CT), including higher spatial and temporal resolution, have made the prospect of performing absolute myocardial perfusion quantification possible, previously only achievable with positron emission tomography (PET). This could facilitate integration of myocardial perfusion biomarkers into the current workup for coronary artery disease (CAD), as MRI and CT systems are more widely available than PET scanners. Cardiac PET scanning remains expensive and is restricted by the requirement of a nearby cyclotron. Clinical evidence is needed to demonstrate that MRI and CT have similar accuracy for myocardial perfusion quantification as PET. However, lack of standardization of acquisition protocols and tracer kinetic model selection complicates comparison between different studies and modalities. The aim of this overview is to provide insight into the different tracer kinetic models for quantitative myocardial perfusion analysis and to address typical implementation issues in MRI and CT. We compare different models based on their theoretical derivations and present the respective consequences for MRI and CT acquisition parameters, highlighting the interplay between tracer kinetic modeling and acquisition settings. PMID:27088083

  3. Graph cut-based method for segmenting the left ventricle from MRI or echocardiographic images.

    PubMed

    Bernier, Michael; Jodoin, Pierre-Marc; Humbert, Olivier; Lalande, Alain

    2017-04-02

    In this paper, we present a fast and interactive graph cut method for 3D segmentation of the endocardial wall of the left ventricle (LV) adapted to work on two of the most widely used modalities: magnetic resonance imaging (MRI) and echocardiography. Our method accounts for the fundamentally different nature of both modalities: 3D echocardiographic images have a low contrast, a poor signal-to-noise ratio and frequent signal drop, while MR images are more detailed but also cluttered and contain highly anisotropic voxels. The main characteristic of our method is to work in a 3D Bezier coordinate system instead of the original Euclidean space. This comes with several advantages, including an implicit shape prior and a result guarantied not to have any holes in it. The proposed method is made of 4 steps. First, a 3D sampling of the LV cavity is made based on a Bezier coordinate system. This allows to warp the input 3D image to a Bezier space in which a plane corresponds to an anatomically plausible 3D Euclidean bullet shape. Second, a 3D graph is built and an energy term (which is based on the image gradient and a 3D probability map) is assigned to each edge of the graph, some of which being given an infinite energy to ensure the resulting 3D structure passes through key anatomical points. Third, a max-flow min-cut procedure is executed on the energy graph to delineate the endocardial surface. And fourth, the resulting surface is projected back to the Euclidean space where a post-processing convex hull algorithm is applied on every short axis slice to remove local concavities. Results obtained on two datasets reveal that our method takes between 2 and 5s to segment a 3D volume, it has better results overall than most state-of-the-art methods on the CETUS echocardiographic dataset and is statistically as good as a human operator on MR images.

  4. MRI-based measurements of respiratory motion variability and assessment of imaging strategies for radiotherapy planning.

    PubMed

    Blackall, J M; Ahmad, S; Miquel, M E; McClelland, J R; Landau, D B; Hawkes, D J

    2006-09-07

    Respiratory organ motion has a significant impact on the planning and delivery of radiotherapy (RT) treatment for lung cancer. Currently widespread techniques, such as 4D-computed tomography (4DCT), cannot be used to measure variability of this motion from one cycle to the next. In this paper, we describe the use of fast magnetic resonance imaging (MRI) techniques to investigate the intra- and inter-cycle reproducibility of respiratory motion and also to estimate the level of errors that may be introduced into treatment delivery by using various breath-hold imaging strategies during lung RT planning. A reference model of respiratory motion is formed to enable comparison of different breathing cycles at any arbitrary position in the respiratory cycle. This is constructed by using free-breathing images from the inhale phase of a single breathing cycle, then co-registering the images, and thereby tracking landmarks. This reference model is then compared to alternative models constructed from images acquired during the exhale phase of the same cycle and the inhale phase of a subsequent cycle, to assess intra- and inter-cycle variability ('hysteresis' and 'reproducibility') of organ motion. The reference model is also compared to a series of models formed from breath-hold data at exhale and inhale. Evaluation of these models is carried out on data from ten healthy volunteers and five lung cancer patients. Free-breathing models show good levels of intra- and inter-cycle reproducibility across the tidal breathing range. Mean intra-cycle errors in the position of organ surface landmarks of 1.5(1.4)-3.5(3.3) mm for volunteers and 2.8(1.8)-5.2(5.2) mm for patients. Equivalent measures of inter-cycle variability across this range are 1.7(1.0)-3.9(3.3) mm for volunteers and 2.8(1.8)-3.3(2.2) mm for patients. As expected, models based on breath-hold sequences do not represent normal tidal motion as well as those based on free-breathing data, with mean errors of 4

  5. Markerless attenuation correction for carotid MRI surface receiver coils in combined PET/MR imaging

    NASA Astrophysics Data System (ADS)

    Eldib, Mootaz; Bini, Jason; Robson, Philip M.; Calcagno, Claudia; Faul, David D.; Tsoumpas, Charalampos; Fayad, Zahi A.

    2015-06-01

    The purpose of the study was to evaluate the effect of attenuation of MR coils on quantitative carotid PET/MR exams. Additionally, an automated attenuation correction method for flexible carotid MR coils was developed and evaluated. The attenuation of the carotid coil was measured by imaging a uniform water phantom injected with 37 MBq of 18F-FDG in a combined PET/MR scanner for 24 min with and without the coil. In the same session, an ultra-short echo time (UTE) image of the coil on top of the phantom was acquired. Using a combination of rigid and non-rigid registration, a CT-based attenuation map was registered to the UTE image of the coil for attenuation and scatter correction. After phantom validation, the effect of the carotid coil attenuation and the attenuation correction method were evaluated in five subjects. Phantom studies indicated that the overall loss of PET counts due to the coil was 6.3% with local region-of-interest (ROI) errors reaching up to 18.8%. Our registration method to correct for attenuation from the coil decreased the global error and local error (ROI) to 0.8% and 3.8%, respectively. The proposed registration method accurately captured the location and shape of the coil with a maximum spatial error of 2.6 mm. Quantitative analysis in human studies correlated with the phantom findings, but was dependent on the size of the ROI used in the analysis. MR coils result in significant error in PET quantification and thus attenuation correction is needed. The proposed strategy provides an operator-free method for attenuation and scatter correction for a flexible MRI carotid surface coil for routine clinical use.

  6. MRI-based elastic-mapping method for inter-subject comparison of brain FDG-PET images

    SciTech Connect

    Yang, J.; Huang, S.C.; Lin, K.P.; Small, G.; Phelps, M.E.

    1996-12-31

    Inter-subject anatomic differences prohibits direct image-wise statistical evaluation of brain FDG-PET images of Alzheimer`s disease (AD) patients. In this study, we propose a MRI-based elastic-mapping method which enables image-wise evaluation. The method involves intra-subject MR-PET registration, 3-D elastic mapping of two set of MR images, and ela