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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. 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.

    1977-01-01

    The use of video-recorded fluoroscopic images as input data for digital reconstruction of objects from their projections is examined. The fluoroscopic and the scanning apparatus used for the experiments are of a commercial type already in existence in most hospitals. It is shown that for beams with divergence up to about 15 deg, one can use a convolution algorithm designed for the parallel radiation case with negligible degradation both quantitatively and from a visual quality standpoint. This convolution algorithm is computationally more efficient than either the algebraic techniques or the convolution algorithms for radially diverging data. Results from studies on Lucite phantoms and a freshly sacrificed rat are included.

  3. Enhancement of fluoroscopic images with varying contrast.

    PubMed

    Ozanian, T O; Phillips, R

    2001-04-01

    A heuristic algorithm for enhancement of fluoroscopic images of varying contrast is proposed. The new technique aims at identifying a suitable type of enhancement for different locations in an image. The estimation relies on simple preliminary classification of image parts into one of the following types: uniform, sharp (with sufficient contrast), detail-containing (structure present) and unknown (for the cases where it is difficult to make a decision). Different smoothing techniques are applied locally in the different types of image parts. For those parts that are classified as detail-containing, probable object boundaries are identified and local sharpening is carried out to increase the contrast at these places. The adopted approach attempts to improve the quality of an image by reducing available noise and simultaneously increasing the contrast at probable object boundaries without increasing the overall dynamic range. In addition, it allows noise to be cleaned, that at some locations is stronger than the fine structure at other locations, whilst preserving the details. PMID:11223147

  4. 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.

  5. 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... SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1650 Image-intensified fluoroscopic x-ray system. (a) Identification. An image-intensified fluoroscopic x-ray system is a...

  6. 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... SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1650 Image-intensified fluoroscopic x-ray system. (a) Identification. An image-intensified fluoroscopic x-ray system is a...

  7. 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... SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1660 Non-image-intensified fluoroscopic x-ray system. (a) Identification. A non-image-intensified fluoroscopic x-ray system is a...

  8. 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... SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1660 Non-image-intensified fluoroscopic x-ray system. (a) Identification. A non-image-intensified fluoroscopic x-ray system is a...

  9. 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... SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1650 Image-intensified fluoroscopic x-ray system. (a) Identification. An image-intensified fluoroscopic x-ray system is a...

  10. 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... SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1660 Non-image-intensified fluoroscopic x-ray system. (a) Identification. A non-image-intensified fluoroscopic x-ray system is a...

  11. 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... SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1650 Image-intensified fluoroscopic x-ray system. (a) Identification. An image-intensified fluoroscopic x-ray system is a...

  12. 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... SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1660 Non-image-intensified fluoroscopic x-ray system. (a) Identification. A non-image-intensified fluoroscopic x-ray system is a...

  13. 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... SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1650 Image-intensified fluoroscopic x-ray system. (a) Identification. An image-intensified fluoroscopic x-ray system is a...

  14. 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... SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1660 Non-image-intensified fluoroscopic x-ray system. (a) Identification. A non-image-intensified fluoroscopic x-ray system is a...

  15. Image-based respiratory motion compensation for fluoroscopic coronary roadmapping.

    PubMed

    Zhu, Ying; Tsin, Yanghai; Sundar, Hari; Sauer, Frank

    2010-01-01

    We present a new image-based respiratory motion compensation method for coronary roadmapping in fluoroscopic images. A temporal analysis scheme is proposed to identify static structures in the image gradient domain. An extended Lucas-Kanade algorithm involving a weighted sum-of-squared-difference (WSSD) measure is proposed to estimate the soft tissue motion in the presence of static structures. A temporally compositional motion model is used to deal with large image motion incurred by deep breathing. Promising results have been shown in the experiments conducted on clinical data. PMID:20879411

  16. 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.

  17. The MEPUC concept adapts the C-arm fluoroscope to image-guided surgery.

    PubMed

    Suhm, Norbert; Müller, Paul; Bopp, Urs; Messmer, Peter; Regazzoni, Pietro

    2004-06-01

    Image-guided surgery requires surgeons to be able to manipulate the imaging modality themselves and without delay. Intraoperative fluoroscopic imaging does not meet this requirement as the C-arm fluoroscope cannot be operated or positioned by the surgeons themselves. The Motorized Exact Positioning Unit for C-arm (MEPUC) concept aims to optimize the workflow of positioning the C-arm fluoroscope. The hardware component of the MEPUC equips the fluoroscope with electric stepping motors. The software component allows the surgeon to control the fluoroscope's movements. The study presented here showed that translational movements within the x-y plane are most frequently performed when positioning the C-arm fluoroscope. Furthermore, reproducing a former projection was found to be a frequent task during image-guided procedures. In our opinion, the MEPUC concept adapts the fluoroscope to image-guided surgery. The most important improvement being definition of a bidirectional data exchange between the surgeon and the C-arm fluoroscope: positioning data from the surgeon to the C-arm fluoroscope and-subsequently-image information from C-arm fluoroscope to the surgeon. PMID:15183713

  18. 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.

  19. The response of fluoroscopic image intensifier-TV systems

    NASA Technical Reports Server (NTRS)

    Baily, N. A.; Keller, R. A.

    1976-01-01

    Three different types of X-ray fluoroscopic TV chains were investigated: two standard clinical units, one with a vidicon camera tube, the other with a plumbicon camera tube; and the third was a large flat-screen unit. In each an X-ray beam generated at 100 kVp was passed through 10 cm of H2O before aluminum absorbers of varying thickness were introduced. Five video recordings were made at each absorber thickness. The video image was digitized directly from the disk recording and quantized into 128 gray levels. The five recordings were averaged on a point-to-point basis, and the central 900 averaged points were again averaged to yield a value for the gray level assigned to each particular image. This 30 by 30 matrix of points corresponds to input screen areas of 29, 8.2, and 3.6 sq cm for the three units investigated.

  20. Radiation exposure to angiographers under different fluoroscopic imaging conditions

    SciTech Connect

    Boone, J.M.; Levin, D.C. )

    1991-09-01

    Radiation levels near an imaging chain commonly used in angiography were measured with both a 100- and a 200-mm-thick scatter phantom. The scatter was measured in lines parallel in space to the central ray of the x-ray beam, at lateral distances of 300, 500, and 800 mm. The effects of fluoroscopic kilovoltage and image intensifier magnification mode were also measured. The results indicate that the highest scattered radiation levels occur near the surface of the patient where the x-ray beam enters. Exposure rates were measured in both anteroposterior (AP) and posteroanterior (PA) geometries on a U-arm system. In PA geometry, the highest radiation levels occur below the angiographer's waist, an area well protected by the lead apron. The AP geometry increases the exposure rate to the neck, head, and upper extremities, areas where apron shielding is less effective.

  1. Auto-shape lossless compression of pharynx and esophagus fluoroscopic images.

    PubMed

    Arif, Arif Sameh; Mansor, Sarina; Logeswaran, Rajasvaran; Karim, Hezerul Abdul

    2015-02-01

    The massive number of medical images produced by fluoroscopic and other conventional diagnostic imaging devices demand a considerable amount of space for data storage. This paper proposes an effective method for lossless compression of fluoroscopic images. The main contribution in this paper is the extraction of the regions of interest (ROI) in fluoroscopic images using appropriate shapes. The extracted ROI is then effectively compressed using customized correlation and the combination of Run Length and Huffman coding, to increase compression ratio. The experimental results achieved show that the proposed method is able to improve the compression ratio by 400 % as compared to that of traditional methods. PMID:25628161

  2. Magnetic Resonance Imaging (MRI)

    MedlinePlus

    ... How Can I Help a Friend Who Cuts? Magnetic Resonance Imaging (MRI) KidsHealth > For Teens > Magnetic Resonance Imaging (MRI) Print A A A Text Size What's ... Exam Safety Getting Your Results What Is MRI? Magnetic resonance imaging (MRI) is a type of safe, painless testing ...

  3. Localization and tracking of aortic valve prosthesis in 2D fluoroscopic image sequences

    NASA Astrophysics Data System (ADS)

    Karar, M.; Chalopin, C.; Merk, D. R.; Jacobs, S.; Walther, T.; Burgert, O.; Falk, V.

    2009-02-01

    This paper presents a new method for localization and tracking of the aortic valve prosthesis (AVP) in 2D fluoroscopic image sequences to assist the surgeon to reach the safe zone of implantation during transapical aortic valve implantation. The proposed method includes four main steps: First, the fluoroscopic images are preprocessed using a morphological reconstruction and an adaptive Wiener filter to enhance the AVP edges. Second, a target window, defined by a user on the first image of the sequences which includes the AVP, is tracked in all images using a template matching algorithm. In a third step the corners of the AVP are extracted based on the AVP dimensions and orientation in the target window. Finally, the AVP model is generated in the fluoroscopic image sequences. Although the proposed method is not yet validated intraoperatively, it has been applied to different fluoroscopic image sequences with promising results.

  4. 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.

  5. Exploiting the multiplicative nature of fluoroscopic image stochastic noise to enhance calcium imaging recording quality.

    PubMed

    Esposti, Federico; Ripamonti, Maddalena; Signorini, Maria G

    2009-01-01

    One of the main problems that affect fluoroscopic imaging is the difficulty in coupling the recorded activity with the morphological information. The comprehension of fluorescence events in relationship with the internal structure of the cell can be very difficult. At this purpose, we developed a new method able to maximize the fluoroscopic movie quality. The method (Maximum Intensity Enhancement, MIE) works as follow: considering all the frames that compose the fluoroscopic movie, the algorithm extracts, for each pixel of the matrix, the maximal brightness value assumed along all the frames. Such values are collected in a maximum intensity matrix. Then, the method provides the projection of the target molecule oscillations which are present in the DeltaF/F(0) movie onto the maximum intensity matrix. This is done by creating a RGB movie and by assigning to the normalized (DeltaF/F(0)) activity a single channel and by reproducing the maximum intensity matrix on all the frames by using the remaining color channels. The application of such a method to fluoroscopic calcium imaging of astrocyte cultures demonstrated a meaningful enhancement in the possibility to discern the internal and external structure of cells. PMID:19964305

  6. 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

  7. 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.

  8. A kernel-based method for markerless tumor tracking in kV fluoroscopic images.

    PubMed

    Zhang, Xiaoyong; Homma, Noriyasu; Ichiji, Kei; Abe, Makoto; Sugita, Norihiro; Takai, Yoshihiro; Narita, Yuichiro; Yoshizawa, Makoto

    2014-09-01

    Markerless tracking of respiration-induced tumor motion in kilo-voltage (kV) fluoroscopic image sequence is still a challenging task in real time image-guided radiation therapy (IGRT). Most of existing markerless tracking methods are based on a template matching technique or its extensions that are frequently sensitive to non-rigid tumor deformation and involve expensive computation. This paper presents a kernel-based method that is capable of tracking tumor motion in kV fluoroscopic image sequence with robust performance and low computational cost. The proposed tracking system consists of the following three steps. To enhance the contrast of kV fluoroscopic image, we firstly utilize a histogram equalization to transform the intensities of original images to a wider dynamical intensity range. A tumor target in the first frame is then represented by using a histogram-based feature vector. Subsequently, the target tracking is then formulated by maximizing a Bhattacharyya coefficient that measures the similarity between the tumor target and its candidates in the subsequent frames. The numerical solution for maximizing the Bhattacharyya coefficient is performed by a mean-shift algorithm. The proposed method was evaluated by using four clinical kV fluoroscopic image sequences. For comparison, we also implement four conventional template matching-based methods and compare their performance with our proposed method in terms of the tracking accuracy and computational cost. Experimental results demonstrated that the proposed method is superior to conventional template matching-based methods. PMID:25098382

  9. A kernel-based method for markerless tumor tracking in kV fluoroscopic images

    NASA Astrophysics Data System (ADS)

    Zhang, Xiaoyong; Homma, Noriyasu; Ichiji, Kei; Abe, Makoto; Sugita, Norihiro; Takai, Yoshihiro; Narita, Yuichiro; Yoshizawa, Makoto

    2014-09-01

    Markerless tracking of respiration-induced tumor motion in kilo-voltage (kV) fluoroscopic image sequence is still a challenging task in real time image-guided radiation therapy (IGRT). Most of existing markerless tracking methods are based on a template matching technique or its extensions that are frequently sensitive to non-rigid tumor deformation and involve expensive computation. This paper presents a kernel-based method that is capable of tracking tumor motion in kV fluoroscopic image sequence with robust performance and low computational cost. The proposed tracking system consists of the following three steps. To enhance the contrast of kV fluoroscopic image, we firstly utilize a histogram equalization to transform the intensities of original images to a wider dynamical intensity range. A tumor target in the first frame is then represented by using a histogram-based feature vector. Subsequently, the target tracking is then formulated by maximizing a Bhattacharyya coefficient that measures the similarity between the tumor target and its candidates in the subsequent frames. The numerical solution for maximizing the Bhattacharyya coefficient is performed by a mean-shift algorithm. The proposed method was evaluated by using four clinical kV fluoroscopic image sequences. For comparison, we also implement four conventional template matching-based methods and compare their performance with our proposed method in terms of the tracking accuracy and computational cost. Experimental results demonstrated that the proposed method is superior to conventional template matching-based methods.

  10. MRI (Magnetic Resonance Imaging)

    MedlinePlus

    ... some MRI exams, intravenous (IV) drugs, such as gadolinium-based contrast agents (GBCAs) are used to change the contrast of the MR image. Gadolinium-based contrast agents are rare earth metals that ...

  11. Radiation Dose Reduction Methods For Use With Fluoroscopic Imaging, Computers And Implications For Image Quality

    NASA Astrophysics Data System (ADS)

    Edmonds, E. W.; Hynes, D. M.; Rowlands, J. A.; Toth, B. D.; Porter, A. J.

    1988-06-01

    The use of a beam splitting device for medical gastro-intestinal fluoroscopy has demonstrated that clinical images obtained with a 100mm photofluorographic camera, and a 1024 X 1024 digital matrix with pulsed progressive readout acquisition techniques, are identical. In addition, it has been found that clinical images can be obtained with digital systems at dose levels lower than those possible with film. The use of pulsed fluoroscopy with intermittent storage of the fluoroscopic image has also been demonstrated to reduce the fluoroscopy part of the examination to very low dose levels, particularly when low repetition rates of about 2 frames per second (fps) are used. The use of digital methods reduces the amount of radiation required and also the heat generated by the x-ray tube. Images can therefore be produced using a very small focal spot on the x-ray tube, which can produce further improvement in the resolution of the clinical images.

  12. Registration of preoperative CTA and intraoperative fluoroscopic image sequence for assisting endovascular stent grafting

    NASA Astrophysics Data System (ADS)

    Imamura, Hiroshi; Sugimoto, Naozo; Eiho, Shigeru; Urayama, Shin-ichi; Ueno, Katsuya; Inoue, Kanji

    2002-05-01

    We have investigated a registration method between pre-operative 3D CT angiography (3D-CTA) and intra-operative fluoroscopic image sequence (with/without contrast injection) during intervention. Most registration methods are developed for assisting neurosurgery or orthopedic surgery, but our method is developed for interventional procedure such as endovascular stent grafting. In our method, DRR (Digitally Reconstructed Radiograph) are generated by voxel projection of 3D-CTA after extracting an aorta region. By increasing/decreasing CT value in the aorta region of CTA, DRR with/without contrast media injection are obtained. Subsequently we calculate distance (or similarity) measures between DRR and fluoroscopic image iteratively by changing imaging parameters. The most similar DRR to fluoroscopy is selected. We validated our algorithm by using simulated/clinical fluoroscopic images and DRR (with/without contrast media injection) of thorax and abdomen. Several distance (or similarity) measures were investigated in this experiment. Validation results show that M-estimator of residual is good as matching measure, and registration is well performed for almost all cases. However, accuracy is not enough for non-contrasted thoracic images, and calculation time should be reduced for all cases.

  13. Echocardiographic and Fluoroscopic Fusion Imaging for Procedural Guidance: An Overview and Early Clinical Experience.

    PubMed

    Thaden, Jeremy J; Sanon, Saurabh; Geske, Jeffrey B; Eleid, Mackram F; Nijhof, Niels; Malouf, Joseph F; Rihal, Charanjit S; Bruce, Charles J

    2016-06-01

    There has been significant growth in the volume and complexity of percutaneous structural heart procedures in the past decade. Increasing procedural complexity and accompanying reliance on multimodality imaging have fueled the development of fusion imaging to facilitate procedural guidance. The first clinically available system capable of echocardiographic and fluoroscopic fusion for real-time guidance of structural heart procedures was approved by the US Food and Drug Administration in 2012. Echocardiographic-fluoroscopic fusion imaging combines the precise catheter and device visualization of fluoroscopy with the soft tissue anatomy and color flow Doppler information afforded by echocardiography in a single image. This allows the interventionalist to perform precise catheter manipulations under fluoroscopy guidance while visualizing critical tissue anatomy provided by echocardiography. However, there are few data available addressing this technology's strengths and limitations in routine clinical practice. The authors provide a critical review of currently available echocardiographic-fluoroscopic fusion imaging for guidance of structural heart interventions to highlight its strengths, limitations, and potential clinical applications and to guide further research into value of this emerging technology. PMID:27021355

  14. X-ray characterization of CMOS imaging detector with high resolution for fluoroscopic imaging application

    NASA Astrophysics Data System (ADS)

    Cha, Bo Kyung; Kim, Cho Rong; Jeon, Seongchae; Kim, Ryun Kyung; Seo, Chang-Woo; Yang, Keedong; Heo, Duchang; Lee, Tae-Bum; Shin, Min-Seok; Kim, Jong-Boo; Kwon, Oh-Kyung

    2013-12-01

    This paper introduces complementary metal-oxide semiconductor (CMOS) active pixel sensor (APS)-based X-ray imaging detectors with high spatial resolution for medical imaging application. In this study, our proposed X-ray CMOS imaging sensor has been fabricated by using a 0.35 μm 1 Poly 4 Metal CMOS process. The pixel size is 100 μm×100 μm and the pixel array format is 24×96 pixels, which provide a field-of-view (FOV) of 9.6 mm×2.4 mm. The 14.3-bit extend counting analog-to digital converter (ADC) with built-in binning mode was used to reduce the area and simultaneously improve the image resolution. Both thallium-doped CsI (CsI:Tl) and Gd2O2S:Tb scintillator screens were used as converters for incident X-rays to visible light photons. The optical property and X-ray imaging characterization such as X-ray to light response as a function of incident X-ray exposure dose, spatial resolution and X-ray images of objects were measured under different X-ray energy conditions. The measured results suggest that our developed CMOS-based X-ray imaging detector has the potential for fluoroscopic imaging and cone-beam computed tomography (CBCT) imaging applications.

  15. Nonrigid 2D registration of fluoroscopic coronary artery image sequence with layered motion

    NASA Astrophysics Data System (ADS)

    Park, Taewoo; Jung, Hoyup; Yun, Il Dong

    2016-03-01

    We present a new method for nonrigid registration of coronary artery models with layered motion information. 2D nonrigid registration method is proposed that brings layered motion information into correspondence with fluoroscopic angiograms. The registered model is overlaid on top of interventional angiograms to provide surgical assistance during image-guided chronic total occlusion procedures. The proposed methodology is divided into two parts: layered structures alignments and local nonrigid registration. In the first part, inpainting method is used to estimate a layered rigid transformation that aligns layered motion information. In the second part, a nonrigid registration method is implemented and used to compensate for any local shape discrepancy. Experimental evaluation conducted on a set of 7 fluoroscopic angiograms results in a reduced target registration error, which showed the effectiveness of the proposed method over single layered approach.

  16. 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.

  17. 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. PMID:2031793

  18. Detection of respiratory motion in fluoroscopic images for adaptive radiotherapy

    NASA Astrophysics Data System (ADS)

    Moser, T.; Biederer, J.; Nill, S.; Remmert, G.; Bendl, R.

    2008-06-01

    Respiratory motion limits the potential of modern high-precision radiotherapy techniques such as IMRT and particle therapy. Due to the uncertainty of tumour localization, the ability of achieving dose conformation often cannot be exploited sufficiently, especially in the case of lung tumours. Various methods have been proposed to track the position of tumours using external signals, e.g. with the help of a respiratory belt or by observing external markers. Retrospectively gated time-resolved x-ray computed tomography (4D CT) studies prior to therapy can be used to register the external signals with the tumour motion. However, during treatment the actual motion of internal structures may be different. Direct control of tissue motion by online imaging during treatment promises more precise information. On the other hand, it is more complex, since a larger amount of data must be processed in order to determine the motion. Three major questions arise from this issue. Firstly, can the motion that has occurred be precisely determined in the images? Secondly, how large must, respectively how small can, the observed region be chosen to get a reliable signal? Finally, is it possible to predict the proximate tumour location within sufficiently short acquisition times to make this information available for gating irradiation? Based on multiple studies on a porcine lung phantom, we have tried to examine these questions carefully. We found a basic characteristic of the breathing cycle in images using the image similarity method normalized mutual information. Moreover, we examined the performance of the calculations and proposed an image-based gating technique. In this paper, we present the results and validation performed with a real patient data set. This allows for the conclusion that it is possible to build up a gating system based on image data, solely, or (at least in avoidance of an exceeding exposure dose) to verify gates proposed by the various external systems.

  19. 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.

  20. 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.

  1. X-ray region of interest imaging system for rapid-sequence angiography and fluoroscopy: The micro-angiographic fluoroscope

    NASA Astrophysics Data System (ADS)

    Wu, Ye

    Neuro-endovascular interventional diagnosis and treatment require high resolution x-ray imaging guidance of fluoroscopy and angiography. Our group has developed a small field of view, 5 frames per second, high-resolution micro-angiographic imager. This imager has demonstrated substantial high-resolution advantages for angiography over the conventional image intensifier. The work of this dissertation is to build a new micro-angiographic fluoroscope (MAF) to expand the capabilities of the micro-angiographic imager to include fluoroscopic imaging over a small field of view. The components of the MAF are all commercially available including CsI (T1) scintillator, fiber-optic taper, light image intensifier (LII), mirror, lens, and CCD camera. The critical component is the microchannel plate based LII with very high spatial resolution. The LII has a large range of gain that can be controlled easily by a 5V to 9V DC voltage. This property enables the MAF to be used for angiography with a low gain of the LII, and for fluoroscopy with a high gain of the LII. This design was justified by the quantum accounting diagram calculation. The preliminary experimental results from the test model MAF demonstrated the feasibility of this design. The improved prototype MAF model demonstrates high-resolution imaging for both fluoroscopy and angiography. The performance descriptors of the prototype MAF such as MTF, NPS, and DQE, were measured in both angiographic mode and fluoroscopic mode. For angiographic mode, at spatial frequencies of 4 and 10 lp/mm, the MTF for the MAF was 14% and 1.5% respectively, the DQE for the MAF was 12% and 1.2% respectively, while the DQE (0) was about 60%. For fluoroscopic mode, at spatial frequency of 4 lp/mm, the MTF for the MAF was 11%, and the DQE for the MAF was 9.5%. The image lag for the MAF in fluoroscopic mode at a rate of 30 fps was measured to be minimal. The allowable maximum entrance exposure rate was found to be related with the maximum LII

  2. Location constraint based 2D-3D registration of fluoroscopic images and CT volumes for image-guided EP procedures

    NASA Astrophysics Data System (ADS)

    Liao, Rui; Xu, Ning; Sun, Yiyong

    2008-03-01

    Presentation of detailed anatomical structures via 3D Computed Tomographic (CT) volumes helps visualization and navigation in electrophysiology procedures (EP). Registration of the CT volume with the online fluoroscopy however is a challenging task for EP applications due to the lack of discernable features in fluoroscopic images. In this paper, we propose to use the coronary sinus (CS) catheter in bi-plane fluoroscopic images and the coronary sinus in the CT volume as a location constraint to accomplish 2D-3D registration. Two automatic registration algorithms are proposed in this study, and their performances are investigated on both simulated and real data. It is shown that compared to registration using mono-plane fluoroscopy, registration using bi-plane images results in substantially higher accuracy in 3D and enhanced robustness. In addition, compared to registering the projection of CS to the 2D CS catheter, it is more desirable to reconstruct a 3D CS catheter from the bi-plane fluoroscopy and then perform a 3D-3D registration between the CS and the reconstructed CS catheter. Quantitative validation based on simulation and visual inspection on real data demonstrates the feasibility of the proposed workflow in EP procedures.

  3. Electrophysiology Catheter Detection and Reconstruction From Two Views in Fluoroscopic Images.

    PubMed

    Hoffmann, Matthias; Brost, Alexander; Koch, Martin; Bourier, Felix; Maier, Andreas; Kurzidim, Klaus; Strobel, Norbert; Hornegger, Joachim

    2016-02-01

    Electrophysiology (EP) studies and catheter ablation have become important treatment options for several types of cardiac arrhythmias. We present a novel image-based approach for automatic detection and 3-D reconstruction of EP catheters where the physician marks the catheter to be reconstructed by a single click in each image. The result can be used to provide 3-D information for enhanced navigation throughout EP procedures. Our approach involves two X-ray projections acquired from different angles, and it is based on two steps: First, we detect the catheter in each view after manual initialization using a graph-search method. Then, the detection results are used to reconstruct a full 3-D model of the catheter based on automatically determined point pairs for triangulation. An evaluation on 176 different clinical fluoroscopic images yielded a detection rate of 83.4%. For measuring the error, we used the coupling distance which is a more accurate quality measure than the average point-wise distance to a reference. For successful outcomes, the 2-D detection error was 1.7 mm ±1.2 mm. Using successfully detected catheters for reconstruction, we obtained a reconstruction error of 1.8 mm ±1.1 mm on phantom data. On clinical data, our method yielded a reconstruction error of 2.2 mm ±2.2 mm. PMID:26441411

  4. Rigorous geometric self-calibrating bundle adjustment for a dual fluoroscopic imaging system.

    PubMed

    Lichti, Derek D; Sharma, Gulshan B; Kuntze, Gregor; Mund, Braden; Beveridge, Jillian E; Ronsky, Janet L

    2015-02-01

    High-speed dual fluoroscopy is a noninvasive imaging technology for three-dimensional skeletal kinematics analysis that finds numerous biomechanical applications. Accurate reconstruction of bone translations and rotations from dual-fluoroscopic data requires accurate calibration of the imaging geometry and the many imaging distortions that corrupt the data. Direct linear transformation methods are commonly applied for performing calibration using a two-step process that suffers from a number of potential shortcomings including that each X-ray source and corresponding camera must be calibrated separately. Consequently, the true imaging set-up and the constraints it presents are not incorporated during calibration. A method to overcome such drawbacks is the single-step self-calibrating bundle adjustment method. This procedure, based on the collinearity principle augmented with imaging distortion models and geometric constraints, has been developed and is reported herein. Its efficacy is shown with a carefully controlled experiment comprising 300 image pairs with 48 507 image points. Application of all geometric constraints and a 31 parameter distortion model resulted in up to 91% improvement in terms of precision (model fit) and up to 71% improvement in terms of 3-D point reconstruction accuracy (0.3-0.4 mm). The accuracy of distance reconstruction was improved from 0.3±2.0 mm to 0.2 ±1.1 mm and angle reconstruction accuracy was improved from -0.03±0.55(°) to 0.01±0.06(°). Such positioning accuracy will allow for the accurate quantification of in vivo arthrokinematics crucial for skeletal biomechanics investigations. PMID:25330483

  5. Directional denoising and line enhancement for device segmentation in real time fluoroscopic imaging

    NASA Astrophysics Data System (ADS)

    Wagner, Martin; Royalty, Kevin; Oberstar, Erick; Strother, Charles; Mistretta, Charles

    2015-03-01

    Purpose: The purpose of this work is to improve the segmentation of interventional devices (e.g. guidewires) in fluoroscopic images. This is required for the real time 3D reconstruction from two angiographic views where noise can cause severe reconstruction artifacts and incomplete reconstruction. The proposed method reduces the noise while enhancing the thin line structures of the device in images with subtracted background. Methods: A two-step approach is presented here. The first step estimates, for each pixel and a given number of directions, a measure for the probability that the point is part of a line segment in the corresponding direction. This can be done efficiently using binary masks. In the second step, a directional filter kernel is applied for pixel that are assumed to be part of a line. For all other pixels a mean filter is used. Results: The proposed algorithm was able to achieve an average contrast to noise ratio (CNR) of 6.3 compared to the bilateral filter with 5.8. For the device segmentation using global thresholding the number of missing or wrong pixels is reduced to 25 % compared to 40 % using the bilateral approach. Conclusion: The proposed algorithm is a simple and efficient approach, which can easily be parallelized for the use on modern graphics processing units. It improves the segmentation results of the device compared to other denoising methods, and therefore reduces artifacts and increases the quality of the reconstruction without increasing the delay in real time applications notably.

  6. Image intensifier distortion correction for fluoroscopic RSA: the need for independent accuracy assessment.

    PubMed

    Kedgley, Angela E; Fox, Anne-Marie V; Jenkyn, Thomas R

    2012-01-01

    Fluoroscopic images suffer from multiple modes of image distortion. Therefore, the purpose of this study was to compare the effects of correction using a range of two-dimensional polynomials and a global approach. The primary measure of interest was the average error in the distances between four beads of an accuracy phantom, as measured using RSA. Secondary measures of interest were the root mean squared errors of the fit of the chosen polynomial to the grid of beads used for correction, and the errors in the corrected distances between the points of the grid in a second position. Based upon the two-dimensional measures, a polynomial of order three in the axis of correction and two in the perpendicular axis was preferred. However, based upon the RSA reconstruction, a polynomial of order three in the axis of correction and one in the perpendicular axis was preferred. The use of a calibration frame for these three-dimensional applications most likely tempers the effects of distortion. This study suggests that distortion correction should be validated for each of its applications with an independent "gold standard" phantom. PMID:22231207

  7. Characterization of a fluoroscopic imaging system for kV and MV radiography.

    PubMed

    Drake, D G; Jaffray, D A; Wong, J W

    2000-05-01

    An on-line kilovoltage (kV) imaging system has been implemented on a medical linear accelerator to verify radiotherapy field placement. A kV x-ray tube is mounted on the accelerator at 90 degrees to the megavoltage (MV) source and shares the same isocenter. Nearly identical CCD-based fluoroscopic imagers are mounted opposite the two x-ray sources. These systems are being used in a clinical study of patient setup error that examines the advantage of kV imaging for on-line localization. In the investigation reported here, the imaging performance of the kV and MV systems are characterized to provide support to the conclusions of the studies of setup error. A spatial-frequency-dependent linear systems model is used to predict the detective quantum efficiencies (DQEs) of the two systems. Each is divided into a series of gain and spreading stages. The parameters of each stage are either measured or obtained from the literature. The model predicts the system gain to within 7% of the measured gain for the MV system and to within 10% for the kV system. The systems' noise power spectra (NPSs) and modulation transfer functions (MTFs) are measured to construct the measured DQEs. X-ray fluences are calculated using modeled polyenergetic spectra. Measured DQEs agree well with those predicted by the model. The model reveals that the MV system is well optimized, and is x-ray quantum noise limited at low spatial frequencies. The kV system is suboptimal, but for purposes of patient positioning yields images superior to those produced by the MV system. This is attributed to the kV system's higher DQE and to the inherently higher contrasts present at kV energies. PMID:10841392

  8. 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.

  9. Teratoma - MRI scan (image)

    MedlinePlus

    This MRI scan shows a tumor (teratoma) at the base of the spine (seen on the left lower edge of the screen), located in the sacrum and coccyx (sacrococcygeal) area. Teratomas are present at birth and may contain hair, teeth, and other tissues.

  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. 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.

  12. 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

  13. Sparse representation of complex MRI images.

    PubMed

    Nandakumar, Hari Prasad; Ji, Jim

    2008-01-01

    Sparse representation of images acquired from Magnet Resonance Imaging (MRI) has several potential applications. MRI is unique in that the raw images are complex. Complex wavelet transforms (CWT) can be used to produce flexible signal representations when compared to Discrete Wavelet Transform (DWT). In this work, five different schemes using CWT or DWT are tested for sparse representation of MRI images which are in the form of complex values, separate real/imaginary, or separate magnitude/phase. The experimental results on real in-vivo MRI images show that appropriate CWT, e.g., dual-tree CWT (DTCWT), can achieve sparsity better than DWT with similar Mean Square Error. PMID:19162677

  14. Live nephron imaging by MRI.

    PubMed

    Qian, Chunqi; Yu, Xin; Pothayee, Nikorn; Dodd, Stephen; Bouraoud, Nadia; Star, Robert; Bennett, Kevin; Koretsky, Alan

    2014-11-15

    The local sensitivity of MRI can be improved with small MR detectors placed close to regions of interest. However, to maintain such sensitivity advantage, local detectors normally need to communicate with the external amplifier through cable connections, which prevent the use of local detectors as implantable devices. Recently, an integrated wireless amplifier was developed that can efficiently amplify and broadcast locally detected signals, so that the local sensitivity was enhanced without the need for cable connections. This integrated detector enabled the live imaging of individual glomeruli using negative contrast introduced by cationized ferritin, and the live imaging of renal tubules using positive contrast introduced by gadopentetate dimeglumine. Here, we utilized the high blood flow to image individual glomeruli as hyperintense regions without any contrast agent. These hyperintense regions were identified for pixels with signal intensities higher than the local average. Addition of Mn(2+) allowed the simultaneous detection of both glomeruli and renal tubules: Mn(2+) was primarily reabsorbed by renal tubules, which would be distinguished from glomeruli due to higher enhancement in T1-weighted MRI. Dynamic studies of Mn(2+) absorption confirmed the differential absorption affinity of glomeruli and renal tubules, potentially enabling the in vivo observation of nephron function. PMID:25186296

  15. MODEL-BASED IMAGE RECONSTRUCTION FOR MRI

    PubMed Central

    Fessler, Jeffrey A.

    2010-01-01

    Magnetic resonance imaging (MRI) is a sophisticated and versatile medical imaging modality. Traditionally, MR images are reconstructed from the raw measurements by a simple inverse 2D or 3D fast Fourier transform (FFT). However, there are a growing number of MRI applications where a simple inverse FFT is inadequate, e.g., due to non-Cartesian sampling patterns, non-Fourier physical effects, nonlinear magnetic fields, or deliberate under-sampling to reduce scan times. Such considerations have led to increasing interest in methods for model-based image reconstruction in MRI. PMID:21135916

  16. MRI Reporter Genes for Noninvasive Molecular Imaging.

    PubMed

    Yang, Caixia; Tian, Rui; Liu, Ting; Liu, Gang

    2016-01-01

    Magnetic resonance imaging (MRI) is one of the most important imaging technologies used in clinical diagnosis. Reporter genes for MRI can be applied to accurately track the delivery of cell in cell therapy, evaluate the therapy effect of gene delivery, and monitor tissue/cell-specific microenvironments. Commonly used reporter genes for MRI usually include genes encoding the enzyme (e.g., tyrosinase and β-galactosidase), the receptor on the cells (e.g., transferrin receptor), and endogenous reporter genes (e.g., ferritin reporter gene). However, low sensitivity limits the application of MRI and reporter gene-based multimodal imaging strategies are common including optical imaging and radionuclide imaging. These can significantly improve diagnostic efficiency and accelerate the development of new therapies. PMID:27213309

  17. 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

  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. Magnetic Resonance Imaging (MRI) -- Head

    MedlinePlus Videos and Cool Tools

    ... any recent surgeries. Some conditions, such as severe kidney disease, may prevent you from being given gadolinium ... an MRI. If you have a history of kidney disease or liver transplant, it will be necessary ...

  20. Evaluation of 3D fluoroscopic image generation from a single planar treatment image on patient data with a modified XCAT phantom

    NASA Astrophysics Data System (ADS)

    Mishra, Pankaj; Li, Ruijiang; St. James, Sara; Mak, Raymond H.; Williams, Christopher L.; Yue, Yong; Berbeco, Ross I.; Lewis, John H.

    2013-02-01

    Accurate understanding and modeling of respiration-induced uncertainties is essential in image-guided radiotherapy. Explicit modeling of the overall lung motion and interaction among different organs promises to be a useful approach. Recently, preliminary studies on 3D fluoroscopic treatment imaging and tumor localization based on principal component analysis motion models and cost function optimization have shown encouraging results. However, the performance of this technique for varying breathing parameters and under realistic conditions remains unclear and thus warrants further investigation. In this work, we present a systematic evaluation of a 3D fluoroscopic image generation algorithm via two different approaches. In the first approach, the model's accuracy is tested for changing parameters for sinusoidal breathing. These parameters include changing respiratory motion amplitude, period and baseline shift. The effects of setup error, imaging noise and different tumor sizes are also examined. In the second approach, we test the model for anthropomorphic images obtained from a modified XCAT phantom. This set of experiments is important as all the underlying breathing parameters are simultaneously tested, as in realistic clinical conditions. Based on our simulation results for more than 250 s of breathing data for eight different lung patients, the overall tumor localization accuracies of the model in left-right, anterior-posterior and superior-inferior directions are 0.1 ± 0.1, 0.5 ± 0.5 and 0.8 ± 0.8 mm, respectively. 3D tumor centroid localization accuracy is 1.0 ± 0.9 mm.

  1. Real-time equalization of region-of-interest fluoroscopic images using binary masks.

    PubMed

    Rudin, S; Bednarek, D R; Yang, C Y

    1999-07-01

    In region-of-interest (ROI) radiologic imaging, the x-ray beam is attenuated peripherally to the region of interest to reduce patient exposure. This attenuation reduces the peripheral image brightness which may cause contrast in the periphery to also be reduced due to video chain nonlinearity. For optimal viewing, it is necessary that the image brightness and contrast in the periphery be brought back to the levels in the ROI. Previously, digital subtraction angiography roadmapping equipment has been used for this equalization; however, the procedure is not independent of patient and gantry motion. A new motion independent method to achieve this equalization involves dividing the real-time video signal into two digital streams one of which is brightness and contrast enhanced. A pre-acquired binary mask image is created by thresholding the image of a uniform object obtained with the ROI filter in place. This binary mask is used to control the recombination of the two image streams in a digital pipeline processor in order to select the ROI from the unprocessed stream and the periphery from the enhanced stream. This system provides image equalization at 30 frame/s for real-time ROI imaging display. Images from this method demonstrate excellent image quality even for peripheral exposure reduction factors exceeding 10. PMID:10435538

  2. 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.

  3. 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.

  4. Automatic segmentation of seeds and fluoroscope tracking (FTRAC) fiducial in prostate brachytherapy x-ray images

    NASA Astrophysics Data System (ADS)

    Kuo, Nathanael; Lee, Junghoon; Deguet, Anton; Song, Danny; Burdette, E. Clif; Prince, Jerry

    2010-02-01

    C-arm X-ray fluoroscopy-based radioactive seed localization for intraoperative dosimetry of prostate brachytherapy is an active area of research. The fluoroscopy tracking (FTRAC) fiducial is an image-based tracking device composed of radio-opaque BBs, lines, and ellipses that provides an effective means for pose estimation so that three-dimensional reconstruction of the implanted seeds from multiple X-ray images can be related to the ultrasound-computed prostate volume. Both the FTRAC features and the brachytherapy seeds must be segmented quickly and accurately during the surgery, but current segmentation algorithms are inhibitory in the operating room (OR). The first reason is that current algorithms require operators to manually select a region of interest (ROI), preventing automatic pipelining from image acquisition to seed reconstruction. Secondly, these algorithms fail often, requiring operators to manually correct the errors. We propose a fast and effective ROI-free automatic FTRAC and seed segmentation algorithm to minimize such human intervention. The proposed algorithm exploits recent image processing tools to make seed reconstruction as easy and convenient as possible. Preliminary results on 162 patient images show this algorithm to be fast, effective, and accurate for all features to be segmented. With near perfect success rates and subpixel differences to manual segmentation, our automatic FTRAC and seed segmentation algorithm shows promising results to save crucial time in the OR while reducing errors.

  5. Geometric Verification of Dynamic Wave Arc Delivery With the Vero System Using Orthogonal X-ray Fluoroscopic Imaging

    SciTech Connect

    Burghelea, Manuela; Verellen, Dirk; Poels, Kenneth; Gevaert, Thierry; Depuydt, Tom; Tournel, Koen; Hung, Cecilia; Simon, Viorica; Hiraoka, Masahiro; Ridder, Mark de

    2015-07-15

    Purpose: The purpose of this study was to define an independent verification method based on on-board orthogonal fluoroscopy to determine the geometric accuracy of synchronized gantry–ring (G/R) rotations during dynamic wave arc (DWA) delivery available on the Vero system. Methods and Materials: A verification method for DWA was developed to calculate O-ring-gantry (G/R) positional information from ball-bearing positions retrieved from fluoroscopic images of a cubic phantom acquired during DWA delivery. Different noncoplanar trajectories were generated in order to investigate the influence of path complexity on delivery accuracy. The G/R positions detected from the fluoroscopy images (DetPositions) were benchmarked against the G/R angulations retrieved from the control points (CP) of the DWA RT plan and the DWA log files recorded by the treatment console during DWA delivery (LogActed). The G/R rotational accuracy was quantified as the mean absolute deviation ± standard deviation. The maximum G/R absolute deviation was calculated as the maximum 3-dimensional distance between the CP and the closest DetPositions. Results: In the CP versus DetPositions comparison, an overall mean G/R deviation of 0.13°/0.16° ± 0.16°/0.16° was obtained, with a maximum G/R deviation of 0.6°/0.2°. For the LogActed versus DetPositions evaluation, the overall mean deviation was 0.08°/0.15° ± 0.10°/0.10° with a maximum G/R of 0.3°/0.4°. The largest decoupled deviations registered for gantry and ring were 0.6° and 0.4° respectively. No directional dependence was observed between clockwise and counterclockwise rotations. Doubling the dose resulted in a double number of detected points around each CP, and an angular deviation reduction in all cases. Conclusions: An independent geometric quality assurance approach was developed for DWA delivery verification and was successfully applied on diverse trajectories. Results showed that the Vero system is capable of following complex

  6. Infrared diaphanoscopy (IRD) and infrared fluoroscopic imaging (IRF) in biological tissue

    NASA Astrophysics Data System (ADS)

    Beuthan, Juergen; Mueller, Gerhard J.; Minet, Olaf; Roggan, Andre; Prapavat, Viravuth

    1993-09-01

    A procedure is described which is based on the imaging of scattered photons in human tissue. This is demonstrated in diagnostic of the maxillary. When an applicator radiation (NIR) is brought into the nasopharynx the photons transmit through the maxillary. In dependence of the optical parameters of the tissue ((mu) a, (mu) s, g) a part of the photons reach the ground of the Orbita, they are scattered there and detected with a CCD-camera which is positioned in front of the maxillary. During disease of the maxillary the optical parameters are changing drastically. The detected part of scattered photons are in correlation with these changes. These changes are demonstrated in IRD-pictures. The IRF is a modification of the IRD. A `light source' is produced in the tissue structure, i.e. during fluorescence angiography through adequate excitation of these markers with laser light. In dependence of the optical parameters of the tissue layers structure relevant scattered light is detectable. With a CCD- camera two dimensional pictures are detected with use of special filter components.

  7. 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.

  8. 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. PMID:21030796

  9. Image quality evaluation and patient dose assessment of medical fluoroscopic X-ray systems: a national study.

    PubMed

    Economides, S; Hourdakis, C J; Kalivas, N; Kalathaki, M; Simantirakis, G; Tritakis, P; Manousaridis, G; Vogiatzi, S; Kipouros, P; Boziari, A; Kamenopoulou, V

    2008-01-01

    This study presents the results from a survey conducted by the Greek Atomic Energy Commission (GAEC), during the period 1998-2003, in 530 public and private owned fluoroscopic X-ray systems in Greece. Certain operational parameters for conventional and remote control systems were assessed, according to a quality control protocol developed by GAEC on the basis of the current literature. Public (91.5%) and private (81.5%) owned fluoroscopic units exhibit high-contrast resolution values over 1 lp mm(-1). Moreover, 88.5 and 87.1% of the fluoroscopic units installed in the public and private sector, respectively, present Maximum Patient Entrance Kerma Rate values lower than 100 mGy min(-1). Additionally, 68.3% of the units assessed were found to perform within the acceptance limits. Finally, the third quartile of the Entrance Surface Dose Rate distribution was estimated according to the Dose Reference Level definition and found equal to 35 mGy min(-1). PMID:17971345

  10. MRI Catheterization in Cardiopulmonary Disease

    PubMed Central

    Rogers, Toby; Ratnayaka, Kanishka

    2014-01-01

    Diagnosis and prognostication in patients with complex cardiopulmonary disease can be a clinical challenge. A new procedure, MRI catheterization, involves invasive right-sided heart catheterization performed inside the MRI scanner using MRI instead of traditional radiographic fluoroscopic guidance. MRI catheterization combines simultaneous invasive hemodynamic and MRI functional assessment in a single radiation-free procedure. By combining both modalities, the many individual limitations of invasive catheterization and noninvasive imaging can be overcome, and additional clinical questions can be addressed. Today, MRI catheterization is a clinical reality in specialist centers in the United States and Europe. Advances in medical device design for the MRI environment will enable not only diagnostic but also interventional MRI procedures to be performed within the next few years. PMID:24394821

  11. 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.

  12. 21 CFR 1020.32 - Fluoroscopic equipment.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... indicating the date of the modification and the statement: Modified to comply with 21 CFR 1020.32(h)(2). (v... indicating the statement: Modified to comply with 21 CFR 1020.32(h)(2). (ii) As an alternative to the... images from the fluoroscopic image receptor, except computed tomography x-ray systems manufactured on...

  13. 21 CFR 1020.32 - Fluoroscopic equipment.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... indicating the date of the modification and the statement: Modified to comply with 21 CFR 1020.32(h)(2). (v... indicating the statement: Modified to comply with 21 CFR 1020.32(h)(2). (ii) As an alternative to the... images from the fluoroscopic image receptor, except computed tomography x-ray systems manufactured on...

  14. 21 CFR 1020.32 - Fluoroscopic equipment.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... indicating the date of the modification and the statement: Modified to comply with 21 CFR 1020.32(h)(2). (v... indicating the statement: Modified to comply with 21 CFR 1020.32(h)(2). (ii) As an alternative to the... images from the fluoroscopic image receptor, except computed tomography x-ray systems manufactured on...

  15. 21 CFR 1020.32 - Fluoroscopic equipment.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... indicating the date of the modification and the statement: Modified to comply with 21 CFR 1020.32(h)(2). (v... indicating the statement: Modified to comply with 21 CFR 1020.32(h)(2). (ii) As an alternative to the... images from the fluoroscopic image receptor, except computed tomography x-ray systems manufactured on...

  16. 21 CFR 1020.32 - Fluoroscopic equipment.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... indicating the date of the modification and the statement: Modified to comply with 21 CFR 1020.32(h)(2). (v... indicating the statement: Modified to comply with 21 CFR 1020.32(h)(2). (ii) As an alternative to the... images from the fluoroscopic image receptor, except computed tomography x-ray systems manufactured on...

  17. 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.

  18. 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.

  19. 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.

  20. MRI

    MedlinePlus

    ... scan is an imaging test that uses powerful magnets and radio waves to create pictures of the ... in your eyes) Because the MRI contains strong magnets, metal objects are not allowed into the room ...

  1. Multiresolution segmentation technique for spine MRI images

    NASA Astrophysics Data System (ADS)

    Li, Haiyun; Yan, Chye H.; Ong, Sim Heng; Chui, Cheekong K.; Teoh, Swee H.

    2002-05-01

    In this paper, we describe a hybrid method for segmentation of spinal magnetic resonance imaging that has been developed based on the natural phenomenon of stones appearing as water recedes. The candidate segmentation region corresponds to the stones with characteristics similar to that of intensity extrema, edges, intensity ridge and grey-level blobs. The segmentation method is implemented based on a combination of wavelet multiresolution decomposition and fuzzy clustering. First thresholding is performed dynamically according to local characteristic to detect possible target areas, We then use fuzzy c-means clustering in concert with wavelet multiscale edge detection to identify the maximum likelihood anatomical and functional target areas. Fuzzy C-Means uses iterative optimization of an objective function based on a weighted similarity measure between the pixels in the image and each of c cluster centers. Local extrema of this objective function are indicative of an optimal clustering of the input data. The multiscale edges can be detected and characterized from local maxima of the modulus of the wavelet transform while the noise can be reduced to some extent by enacting thresholds. The method provides an efficient and robust algorithm for spinal image segmentation. Examples are presented to demonstrate the efficiency of the technique on some spinal MRI images.

  2. 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

  3. PET/MRI in Oncological Imaging: State of the Art

    PubMed Central

    Bashir, Usman; Mallia, Andrew; Stirling, James; Joemon, John; MacKewn, Jane; Charles-Edwards, Geoff; Goh, Vicky; Cook, Gary J.

    2015-01-01

    Positron emission tomography (PET) combined with magnetic resonance imaging (MRI) is a hybrid technology which has recently gained interest as a potential cancer imaging tool. Compared with CT, MRI is advantageous due to its lack of ionizing radiation, superior soft-tissue contrast resolution, and wider range of acquisition sequences. Several studies have shown PET/MRI to be equivalent to PET/CT in most oncological applications, possibly superior in certain body parts, e.g., head and neck, pelvis, and in certain situations, e.g., cancer recurrence. This review will update the readers on recent advances in PET/MRI technology and review key literature, while highlighting the strengths and weaknesses of PET/MRI in cancer imaging. PMID:26854157

  4. PET/MRI in Oncological Imaging: State of the Art.

    PubMed

    Bashir, Usman; Mallia, Andrew; Stirling, James; Joemon, John; MacKewn, Jane; Charles-Edwards, Geoff; Goh, Vicky; Cook, Gary J

    2015-01-01

    Positron emission tomography (PET) combined with magnetic resonance imaging (MRI) is a hybrid technology which has recently gained interest as a potential cancer imaging tool. Compared with CT, MRI is advantageous due to its lack of ionizing radiation, superior soft-tissue contrast resolution, and wider range of acquisition sequences. Several studies have shown PET/MRI to be equivalent to PET/CT in most oncological applications, possibly superior in certain body parts, e.g., head and neck, pelvis, and in certain situations, e.g., cancer recurrence. This review will update the readers on recent advances in PET/MRI technology and review key literature, while highlighting the strengths and weaknesses of PET/MRI in cancer imaging. PMID:26854157

  5. 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

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

    PubMed Central

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

    2011-01-01

    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 μm 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. 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

  8. Fluoroscopic dose reduction using a digital television nose-reduction device

    SciTech Connect

    Albow, R.C.; Jaffe, C.C.; Orphanoudakis, S.C.; Markowitz, R.I.; Rosenfield, N.S.

    1983-07-01

    A digital video image processor, connected to a video system in a conventional pediatric fluoroscopy room, was used to determine whether the device could provide satisfactory fluoroscopic images during routine examinations when the x-ray tube was operated at substantially lower than normal radiation-dose levels. A 50% reduction resulted in image quality which was indistinguishable from conventional fluoroscopic views.

  9. 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.

  10. 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.

  11. Future image acquisition trends for PET/MRI.

    PubMed

    Boss, Andreas; Weiger, Markus; Wiesinger, Florian

    2015-05-01

    Hybrid PET/MRI scanners have become commercially available in the past years but are not yet widely distributed. The combination of a state-of-the-art PET with a state-of-the-art MRI scanner provides numerous potential advantages compared with the established PET/CT hybrid systems, namely, increased soft tissue contrast; functional information from MRI such as diffusion, perfusion, and blood oxygenation level-dependent techniques; true multiplanar data acquisition; and reduced radiation exposure. On the contrary, current PET/MRI technology is hampered by several shortcomings compared with PET/CT, the most important issues being how to use MR data for PET attenuation correction and the low sensitivity of MRI for small-scale pulmonary pathologies compared with high-resolution CT. Moreover, the optimal choice for hybrid PET/MRI acquisition protocols needs to be defined providing the highest possible degree of sensitivity and specificity within the constraints of the available measurement time. A multitude of new acquisition strategies of PET and MRI not only offer to overcome current obstacles of hybrid PET/MRI but also provide deeper insights into the pathophysiology of oncological, inflammatory, or degenerative diseases from the combination of molecular and functional imaging techniques. PMID:25841275

  12. Magnetic Resonance Imaging (MRI) and Positron Emission Tomography (PET)/MRI for Lung Cancer Staging.

    PubMed

    Ohno, Yoshiharu; Koyama, Hisanobu; Lee, Ho Yun; Yoshikawa, Takeshi; Sugimura, Kazuro

    2016-07-01

    Tumor, lymph node, and metastasis (TNM) classification of lung cancer is typically performed with the TNM staging system, as recommended by the Union Internationale Contre le Cancer (UICC), the American Joint Committee on Cancer (AJCC), and the International Association for the Study of Lung Cancer (IASLC). Radiologic examinations for TNM staging of lung cancer patients include computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomography with 2-[fluorine-18] fluoro-2-deoxy-D-glucose (FDG-PET), and FDG-PET combined with CT (FDG-PET/CT) and are used for pretherapeutic assessments. Recent technical advances in MR systems, application of fast and parallel imaging and/or introduction of new MR techniques, and utilization of contrast media have markedly improved the diagnostic utility of MRI in this setting. In addition, FDG-PET can be combined or fused with MRI (PET/MRI) for clinical practice. This review article will focus on these recent advances in MRI as well as on PET/MRI for lung cancer staging, in addition to a discussion of their potential and limitations for routine clinical practice in comparison with other modalities such as CT, FDG-PET, and PET/CT. PMID:27075745

  13. Texture analysis on MRI images of non-Hodgkin lymphoma.

    PubMed

    Harrison, L; Dastidar, P; Eskola, H; Järvenpää, R; Pertovaara, H; Luukkaala, T; Kellokumpu-Lehtinen, P-L; Soimakallio, S

    2008-04-01

    The aim here is to show that texture parameters of magnetic resonance imaging (MRI) data changes in lymphoma tissue during chemotherapy. Ten patients having non-Hodgkin lymphoma masses in the abdomen were imaged for chemotherapy response evaluation three consecutive times. The analysis was performed with MaZda texture analysis (TA) application. The best discrimination in lymphoma MRI texture was obtained within T2-weighted images between the pre-treatment and the second response evaluation stage. TA proved to be a promising quantitative means of representing lymphoma tissue changes during medication follow-up. PMID:18342845

  14. 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 .

  15. Assessment of radiofrequency ablation margin by MRI-MRI image fusion in hepatocellular carcinoma

    PubMed Central

    Wang, Xiao-Li; Li, Kai; Su, Zhong-Zhen; Huang, Ze-Ping; Wang, Ping; Zheng, Rong-Qin

    2015-01-01

    AIM: To investigate the feasibility and clinical value of magnetic resonance imaging (MRI)-MRI image fusion in assessing the ablative margin (AM) for hepatocellular carcinoma (HCC). METHODS: A newly developed ultrasound workstation for MRI-MRI image fusion was used to evaluate the AM of 62 tumors in 52 HCC patients after radiofrequency ablation (RFA). The lesions were divided into two groups: group A, in which the tumor was completely ablated and 5 mm AM was achieved (n = 32); and group B, in which the tumor was completely ablated but 5 mm AM was not achieved (n = 29). To detect local tumor progression (LTP), all patients were followed every two months by contrast-enhanced ultrasound, contrast-enhanced MRI or computed tomography (CT) in the first year after RFA. Then, the follow-up interval was prolonged to every three months after the first year. RESULTS: Of the 62 tumors, MRI-MRI image fusion was successful in 61 (98.4%); the remaining case had significant deformation of the liver and massive ascites after RFA. The time required for creating image fusion and AM evaluation was 15.5 ± 5.5 min (range: 8-22 min) and 9.6 ± 3.2 min (range: 6-14 min), respectively. The follow-up period ranged from 1-23 mo (14.2 ± 5.4 mo). In group A, no LTP was detected in 32 lesions, whereas in group B, LTP was detected in 4 of 29 tumors, which occurred at 2, 7, 9, and 15 mo after RFA. The frequency of LTP in group B (13.8%; 4/29) was significantly higher than that in group A (0/32, P = 0.046). All of the LTPs occurred in the area in which the 5 mm AM was not achieved. CONCLUSION: The MRI-MRI image fusion using an ultrasound workstation is feasible and useful for evaluating the AM after RFA for HCC. PMID:25954109

  16. 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. PMID:24027619

  17. 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.

  18. 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 Central

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

    2012-01-01

    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. PMID:24027619

  19. 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

  20. 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.

  1. 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

  2. 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. PMID:26041266

  3. Simultaneous imaging using Si-PM-based PET and MRI for development of an integrated PET/MRI system

    NASA Astrophysics Data System (ADS)

    Yamamoto, Seiichi; Watabe, Tadashi; Watabe, Hiroshi; Aoki, Masaaki; Sugiyama, Eiji; Imaizumi, Masao; Kanai, Yasukazu; Shimosegawa, Eku; Hatazawa, Jun

    2012-01-01

    The silicon photomultiplier (Si-PM) is a promising photo-detector for PET for use in magnetic resonance imaging (MRI) systems because it has high gain and is insensitive to static magnetic fields. Recently we developed a Si-PM-based depth-of-interaction PET system for small animals and performed simultaneous measurements by combining the Si-PM-based PET and the 0.15 T permanent MRI to test the interferences between the Si-PM-based PET and an MRI. When the Si-PM was inside the MRI and installed around the radio frequency (RF) coil of the MRI, significant noise from the RF sequence of the MRI was observed in the analog signals of the PET detectors. However, we did not observe any artifacts in the PET images; fluctuation increased in the count rate of the Si-PM-based PET system. On the MRI side, there was significant degradation of the signal-to-noise ratio (S/N) in the MRI images compared with those without PET. By applying noise reduction procedures, the degradation of the S/N was reduced. With this condition, simultaneous measurements of a rat brain using a Si-PM-based PET and an MRI were made with some degradation in the MRI images. We conclude that simultaneous measurements are possible using Si-PM-based PET and MRI.

  4. 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.

  5. 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 Central

    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. PMID:18958294

  6. 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)

    NASA Astrophysics Data System (ADS)

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

    2008-03-01

    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 1024X1024 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.

  7. Pitfalls of adrenal imaging with chemical shift MRI.

    PubMed

    Schieda, N; Al Dandan, O; Kielar, A Z; Flood, T A; McInnes, M D F; Siegelman, E S

    2014-11-01

    Chemical shift (CS) MRI of the adrenal glands exploits the different precessional frequencies of fat and water protons to differentiate the intracytoplasmic lipid-containing adrenal adenoma from other adrenal lesions. The purpose of this review is to illustrate both technical and interpretive pitfalls of adrenal imaging with CS MRI and emphasize the importance of adherence to strict technical specifications and errors that may occur when other imaging features and clinical factors are not incorporated into the diagnosis. When performed properly, the specificity of CS MRI for the diagnosis of adrenal adenoma is over 90%. Sampling the in-phase and opposed-phase echoes in the correct order and during the same breath-hold are essential requirements, and using the first echo pair is preferred, if possible. CS MRI characterizes more adrenal adenomas then unenhanced CT but may be non-diagnostic in a proportion of lipid-poor adenomas; CT washout studies may be able to diagnose these lipid-poor adenomas. Other primary and secondary adrenal tumours and supra-renal disease entities may contain lipid or gross fat and mimic adenoma or myelolipoma. Heterogeneity within an adrenal lesion that contains intracytoplasmic lipid could be due to myelolipoma, lipomatous metaplasia of adenoma, or collision tumour. Correlation with previous imaging, other imaging features, clinical history, and laboratory investigations can minimize interpretive errors. PMID:25062926

  8. 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

  9. SQUID-sensor-based ultra-low-field MRI calibration with phantom images: Towards quantitative imaging

    NASA Astrophysics Data System (ADS)

    Dabek, Juhani; Vesanen, Panu T.; Zevenhoven, Koos C. J.; Nieminen, Jaakko O.; Sepponen, Raimo; Ilmoniemi, Risto J.

    2012-11-01

    In ultra-low-field magnetic resonance imaging (ULF MRI), measured resonance signals oscillate at Larmor frequencies around 1 kHz compared to even above 100 MHz in high-field MRI. Thus, detection by induction coils in ULF MRI is not feasible, whereas superconducting quantum interference device (SQUID) sensors can measure these femtotesla-level signals. The signal-to-noise ratio is enhanced by prepolarization in a field that is typically 100-1000 times higher than the field during acquisition. Based on both measurements and simulations, a procedure for calibrating a SQUID-sensor-based MRI system with MR images is presented in this article. Magnetoencephalography (MEG) can be integrated with ULF MRI, and may also benefit from such a calibration procedure. Conventionally, electromagnet probe signals have been used for the SQUID-sensor calibration in MEG; the presented ULF-MRI-based approach using an imaging phantom could replace this procedure in hybrid MEG-MRI or ULF MRI alone. The necessary theory is provided here with experimental verification. The calibration procedure opens the possibility of performing quantitative ULF MRI without sample-specific reference scans.

  10. Magnetic resonance imaging (MRI) of bruises: a pilot study.

    PubMed

    Langlois, Neil E I; Ross, Claire G; Byard, Roger W

    2013-09-01

    The purpose of this study was to investigate if magnetic resonance imaging (MRI) could be used to image the presence of hemosiderin in bruises and if there was the potential for this technique to be applied as a non-invasive method to estimate the age of bruises. To achieve this aim an animal model to produce lesions resembling bruises was created by injecting blood obtained from the tail vein subcutaneously into an area of the abdominal wall. The animals were euthanized at 3, 6, 12 h, 1, 2, 3, 5, and 7 days post injection and the skin of the abdominal wall was excised for MRI scanning and histological examination. The injected blood appeared as hypointense (dark) areas on the T2* MRI at 3 and 6 h. The image of the injected areas became indistinct at 12 h and continued to be indistinct at 1 and 2 days, although there appeared to be transitioning from hypointensity to hyperintensity (light). The magnetic resonance image appeared to better correspond to the histological appearance at 3 and 5 days, with the "bruise" appearing hyperintense (white); however, some hypointense (darker) areas at 3 day possibly corresponded to the development of hemosiderin. At 7 day the injected blood had been converted to hemosiderin with possible correlation between areas of blue staining in Perls' stained histologic sections and areas of extreme hypointensity in the T2* magnetic resonance image. This study has shown that a series of changes occur on MRI of bruises in an animal model that may relate to histological changes. Although variability in the intensity of the MRI signal and considerable soft tissue artifact currently make interpretations difficult, this may be a technique worth pursuing in the non-invasive evaluation of bruises. PMID:23760862

  11. Magnetic Particle Imaging (MPI) for NMR and MRI Researchers

    PubMed Central

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

    2012-01-01

    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. PMID:23305842

  12. 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.

  13. 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

  14. Fluoroscopic tomography. [for body section synthesis

    NASA Technical Reports Server (NTRS)

    Baily, N. A.; Crepeau, R. L.; Lasser, E. C.

    1974-01-01

    A fluoroscopic tomography system capable of synthesizing body sections at a number of levels within the body has been developed. The synthesized body sections may lie either in a range of planes parallel to, tilted with respect to, skewed with respect to, or both tilted and skewed with respect to the plane of motion of the X-ray tube target. In addition, body sections can be presented which are contoured to the patient's anatomy. That is to say, they may even encompass such complex surfaces as a quadratic hyperplane. In addition, tomograms of organs in motion can be imaged.

  15. Lossless Compression on MRI Images Using SWT.

    PubMed

    Anusuya, V; Raghavan, V Srinivasa; Kavitha, G

    2014-10-01

    Medical image compression is one of the growing research fields in biomedical applications. Most medical images need to be compressed using lossless compression as each pixel information is valuable. With the wide pervasiveness of medical imaging applications in health-care settings and the increased interest in telemedicine technologies, it has become essential to reduce both storage and transmission bandwidth requirements needed for archival and communication of related data, preferably by employing lossless compression methods. Furthermore, providing random access as well as resolution and quality scalability to the compressed data has become of great utility. Random access refers to the ability to decode any section of the compressed image without having to decode the entire data set. The system proposes to implement a lossless codec using an entropy coder. 3D medical images are decomposed into 2D slices and subjected to 2D-stationary wavelet transform (SWT). The decimated coefficients are compressed in parallel using embedded block coding with optimized truncation of the embedded bit stream. These bit streams are decoded and reconstructed using inverse SWT. Finally, the compression ratio (CR) is evaluated to prove the efficiency of the proposal. As an enhancement, the proposed system concentrates on minimizing the computation time by introducing parallel computing on the arithmetic coding stage as it deals with multiple subslices. PMID:24848945

  16. 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. PMID:27236222

  17. 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

  18. Brain CT and MRI: differential diagnosis of imaging findings.

    PubMed

    Masdeu, Joseph C; Gadhia, Rajan; Faridar, Alireza

    2016-01-01

    Following a traditional approach, in Chapters 5 and 14-29 in the previous volume, diverse brain diseases are listed and their imaging findings described in detail. In this chapter the approach is from the imaging finding to the disease: for instance, what list of diseases can give rise to a contrast-enhancing mass in the cerebellopontine angle? Imaging findings that are reviewed in succession include the location of the lesion, its multiplicity and symmetry, its volume, ranging from atrophy to mass effect, its homogeneity, its density, measurable by computed tomography (CT), its appearance on T1, T2, and diffusion magnetic resonance imaging (MRI), and, finally, its characteristics after the infusion of intravenous contrast. A differential diagnosis for each finding is provided. While the approach adopted in this chapter is unconventional, we hope that it will be most helpful to anyone reading images. Furthermore, it could serve as the basis to create or complete image databases to guide in the interpretation of brain CT and MRI. PMID:27430457

  19. Photo-magnetic imaging: resolving optical contrast at MRI resolution

    NASA Astrophysics Data System (ADS)

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

    2013-06-01

    In this paper, we establish the mathematical framework of a novel imaging technique, namely photo-magnetic imaging (PMI). PMI uses a 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 the optical contrast at MRI spatial resolution. The image reconstruction for PMI, using a finite-element-based algorithm with an 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 are recovered as a single 6 mm diameter object with DOT. However, these two objects are not only effectively resolved with PMI, but their true concentrations are also recovered successfully.

  20. 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.

  1. 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.

  2. Automatic determination of the imaging plane in lumbar MRI

    NASA Astrophysics Data System (ADS)

    Masaki, Tsurumaki; Lee, Yongbum; Tsai, Du-Yih; Sekiya, Masaru; Kazama, Kiyoko

    2006-03-01

    In this paper we describe a method for assisting radiological technologists in their routine work to automatically determine the imaging plane in lumbar MRI. The method is first to recognize the spinal cord and the intervertebral disk (ID) from the lumbar vertebra 3-plane localizer image, and then the imaging plane is automatically determined according to the recognition results. To determine the imaging plane, the spinal cord and the ID are automatically recognized from the lumbar vertebra 3-plane localizer image with a series of image processing techniques. The proposed method consists of three major steps. First, after removing the air and fat regions from the 3-plane localizer image by use of histogram analysis, the rachis region is specified with Sobel edge detection filter. Second, the spinal cord and the ID were respectively extracted from the specified rachis region making use of global thresholding and the line detection filter. Finally, the imaging plane is determined by finding the straight line between the spinal cord and the ID with the Hough transform. Image data of 10 healthy volunteers were used for investigation. To validate the usefulness of our proposed method, manual determination of the imaging plane was also conducted by five experienced radiological technologists. Our experimental results showed that the concordance rate between the manual setting and automatic determination reached to 90%. Moreover, a remarkable reduction in execution time for imaging-plane determination was also achieved.

  3. 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

  4. Statistical shape model-based segmentation of brain MRI images.

    PubMed

    Bailleul, Jonathan; Ruan, Su; Constans, Jean-Marc

    2007-01-01

    We propose a segmentation method that automatically delineates structures contours from 3D brain MRI images using a statistical shape model. We automatically build this 3D Point Distribution Model (PDM) in applying a Minimum Description Length (MDL) annotation to a training set of shapes, obtained by registration of a 3D anatomical atlas over a set of patients brain MRIs. Delineation of any structure from a new MRI image is first initialized by such registration. Then, delineation is achieved in iterating two consecutive steps until the 3D contour reaches idempotence. The first step consists in applying an intensity model to the latest shape position so as to formulate a closer guess: our model requires far less priors than standard model in aiming at direct interpretation rather than compliance to learned contexts. The second step consists in enforcing shape constraints onto previous guess so as to remove all bias induced by artifacts or low contrast on current MRI. For this, we infer the closest shape instance from the PDM shape space using a new estimation method which accuracy is significantly improved by a huge increase in the model resolution and by a depth-search in the parameter space. The delineation results we obtained are very encouraging and show the interest of the proposed framework. PMID:18003193

  5. Nanomedicine strategies for molecular targets with MRI and optical imaging

    PubMed Central

    Pan, Dipanjan; Caruthers, Shelton D; Chen, Junjie; Winter, Patrick M; SenPan, Angana; Schmieder, Anne H; Wickline, Samuel A

    2010-01-01

    The science of ‘theranostics’ plays a crucial role in personalized medicine, which represents the future of patient management. Over the last decade an increasing research effort has focused on the development of nanoparticle-based molecular-imaging and drug-delivery approaches, emerging as a multidisciplinary field that shows promise in understanding the components, processes, dynamics and therapies of a disease at a molecular level. The potential of nanometer-sized agents for early detection, diagnosis and personalized treatment of diseases is extraordinary. They have found applications in almost all clinically relevant biomedical imaging modality. In this review, a number of these approaches will be presented with a particular emphasis on MRI and optical imaging-based techniques. We have discussed both established molecular-imaging approaches and recently developed innovative strategies, highlighting the seminal studies and a number of successful examples of theranostic nanomedicine, especially in the areas of cardiovascular and cancer therapy. PMID:20485473

  6. 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.

  7. 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. PMID:27091626

  8. FTRAC--A robust fluoroscope tracking fiducial

    SciTech Connect

    Jain, Ameet Kumar; Mustafa, Tabish; Zhou, Yu; Burdette, Clif; Chirikjian, Gregory S.; Fichtinger, Gabor

    2005-10-15

    C-arm fluoroscopy is ubiquitous in contemporary surgery, but it lacks the ability to accurately reconstruct three-dimensional (3D) information. A major obstacle in fluoroscopic reconstruction is discerning the pose of the x-ray image, in 3D space. Optical/magnetic trackers tend to be prohibitively expensive, intrusive and cumbersome in many applications. We present single-image-based fluoroscope tracking (FTRAC) with the use of an external radiographic fiducial consisting of a mathematically optimized set of ellipses, lines, and points. This is an improvement over contemporary fiducials, which use only points. The fiducial encodes six degrees of freedom in a single image by creating a unique view from any direction. A nonlinear optimizer can rapidly compute the pose of the fiducial using this image. The current embodiment has salient attributes: small dimensions (3x3x5 cm); need not be close to the anatomy of interest; and accurately segmentable. We tested the fiducial and the pose recovery method on synthetic data and also experimentally on a precisely machined mechanical phantom. Pose recovery in phantom experiments had an accuracy of 0.56 mm in translation and 0.33 deg. in orientation. Object reconstruction had a mean error of 0.53 mm with 0.16 mm STD. The method offers accuracies similar to commercial tracking systems, and appears to be sufficiently robust for intraoperative quantitative C-arm fluoroscopy. Simulation experiments indicate that the size can be further reduced to 1x1x2 cm, with only a marginal drop in accuracy.

  9. 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

  10. 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

  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. 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. PMID:9498605

  13. Simulation of 3D MRI brain images for quantitative evaluation of image segmentation algorithms

    NASA Astrophysics Data System (ADS)

    Wagenknecht, Gudrun; Kaiser, Hans-Juergen; Obladen, Thorsten; Sabri, Osama; Buell, Udalrich

    2000-06-01

    To model the true shape of MRI brain images, automatically classified T1-weighted 3D MRI images (gray matter, white matter, cerebrospinal fluid, scalp/bone and background) are utilized for simulation of grayscale data and imaging artifacts. For each class, Gaussian distribution of grayscale values is assumed, and mean and variance are computed from grayscale images. A random generator fills up the class images with Gauss-distributed grayscale values. Since grayscale values of neighboring voxels are not correlated, a Gaussian low-pass filtering is done, preserving class region borders. To simulate anatomical variability, a Gaussian distribution in space with user-defined mean and variance can be added at any user-defined position. Several imaging artifacts can be added: (1) to simulate partial volume effects, every voxel is averaged with neighboring voxels if they have a different class label; (2) a linear or quadratic bias field can be added with user-defined strength and orientation; (3) additional background noise can be added; and (4) artifacts left over after spoiling can be simulated by adding a band with increasing/decreasing grayscale values. With this method, realistic-looking simulated MRI images can be produced to test classification and segmentation algorithms regarding accuracy and robustness even in the presence of artifacts.

  14. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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.

  16. 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. PMID:25925128

  17. Advances in multimodality imaging through a hybrid PET/MRI system.

    PubMed

    Fatemi-Ardekani, Ali; Samavati, Navid; Tang, Jin; Kamath, Markad V

    2009-01-01

    The development of integrated imaging systems for magnetic resonance imaging (MRI) and positron emission tomography (PET) is currently being explored in a number of laboratories and industrial settings. PET/MRI scanners for both preclinical and human research applications are being developed. PET/MRI overcomes many limitations of PET/computed tomography (CT), such as limited tissue contrast and high radiation doses delivered to the patient or the animal being studied. In addition, recent PET/MRI designs allow for simultaneous rather than sequential acquisition of PET and MRI data, which could not have been achieved through a combination of PET and CT scanners. In a combined PET/CT scanner, while both scanners share a common patient bed, they are hard-wired back-to-back and therefore do not allow simultaneous data acquisition. While PET/MRI offers the possibility of novel imaging strategies, it also creates considerable challenges for acquiring artifact-free images from both modalities. In this review, we discuss motivations, challenges, and potential research applications of developing PET/MRI technology. A brief overview of both MRI and PET is presented and preclinical and clinical applications of PET/MRI are identified. Finally, issues and concerns about image quality, clinical practice, and economic feasibility are discussed. PMID:20565381

  18. Evolution of imaging in rectal cancer: multimodality imaging with MDCT, MRI, and PET.

    PubMed

    Raman, Siva P; Chen, Yifei; Fishman, Elliot K

    2015-04-01

    Magnetic resonance imaging (MRI), multidetector computed tomography (MDCT), and positron emission tomography (PET) are complementary imaging modalities in the preoperative staging of patients with rectal cancer, and each offers their own individual strengths and weaknesses. MRI is the best available radiologic modality for the local staging of rectal cancers, and can play an important role in accurately distinguishing which patients should receive preoperative chemoradiation prior to total mesorectal excision. Alternatively, both MDCT and PET are considered primary modalities when performing preoperative distant staging, but are limited in their ability to locally stage rectal malignancies. This review details the role of each of these three modalities in rectal cancer staging, and how the three imaging modalities can be used in conjunction. PMID:25830037

  19. Evolution of imaging in rectal cancer: multimodality imaging with MDCT, MRI, and PET

    PubMed Central

    Chen, Yifei; Fishman, Elliot K.

    2015-01-01

    Magnetic resonance imaging (MRI), multidetector computed tomography (MDCT), and positron emission tomography (PET) are complementary imaging modalities in the preoperative staging of patients with rectal cancer, and each offers their own individual strengths and weaknesses. MRI is the best available radiologic modality for the local staging of rectal cancers, and can play an important role in accurately distinguishing which patients should receive preoperative chemoradiation prior to total mesorectal excision. Alternatively, both MDCT and PET are considered primary modalities when performing preoperative distant staging, but are limited in their ability to locally stage rectal malignancies. This review details the role of each of these three modalities in rectal cancer staging, and how the three imaging modalities can be used in conjunction. PMID:25830037

  20. 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

  1. 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.

  2. MRI imaging of displaced meniscal tears: Report of a case highlighting new potential pitfalls of the MRI signs

    PubMed Central

    Prasad, Abhishek; Brar, Rahat; Rana, Shaleen

    2014-01-01

    Magnetic resonance imaging (MRI) has been found to be an excellent imaging tool for meniscal injuries. Various MRI signs have been described to detect displaced meniscal injuries, specifically the bucket-handle tears. Although these signs are quite helpful in diagnosing meniscal tears, various pitfalls have also been reported for these signs. Double anterior cruciate ligament (ACL) sign refers to presence of a linear hypointense soft tissue anterior to the ACL, which represented the flipped bucket-handle tear of the meniscus. Disproportional posterior horn and flipped meniscus signs represent asymmetrically thickened horns of the menisci due to overlying displaced meniscal fragments. We report a case wherein MRI of the knee showed tear and displacement of the medial patellofemoral ligament (MPFL) and vastus medialis complex, medial collateral ligament (MCL), and posterior cruciate ligament (PCL) mimicking these signs. To our knowledge, internally displaced MPFL and MCLs have not been described as mimics for displaced meniscal fragments. PMID:25114394

  3. 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

  4. 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.

  5. 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

  6. Imaging in head and neck squamous cell carcinoma: the potential role of PET/MRI

    PubMed Central

    Zaidi, Habib

    2014-01-01

    In head and neck oncology, the information provided by positron emission tomography (PET)/CT and MRI is often complementary because both the methods are based on different biophysical foundations. Therefore, combining diagnostic information from both modalities can provide additional diagnostic gain. Debates about integrated PET/MRI systems have become fashionable during the past few years, since the introduction and wide adoption of software-based multimodality image registration and fusion and the hardware implementation of integrated hybrid PET/MRI systems in pre-clinical and clinical settings. However, combining PET with MRI has proven to be technically and clinically more challenging than initially expected and, as such, research into the potential clinical role of PET/MRI in comparison with PET/CT, diffusion-weighted MRI (DW MRI) or the combination thereof is still ongoing. This review focuses on the clinical applications of PET/MRI in head and neck squamous cell carcinoma (HNSCC). We first discuss current evidence about the use of combined PET/CT and DW MRI, and, then, we explain the rationale and principles of PET/MR image fusion before summarizing the state-of-the-art knowledge regarding the diagnostic performance of PET/MRI in HNSCC. Feasibility and quantification issues, diagnostic pitfalls and challenges in clinical settings as well as ongoing research and potential future applications are also discussed. PMID:24649835

  7. Assessing the reliability of MRI-CBCT image registration to visualize temporomandibular joints

    PubMed Central

    Jaremko, J L; Alsufyani, N; Jibri, Z; Lai, H; Major, P W

    2015-01-01

    Objectives: To evaluate image quality of two methods of registering MRI and CBCT images of the temporomandibular joint (TMJ), particularly regarding TMJ articular disc–condyle relationship and osseous abnormality. Methods: MR and CBCT images for 10 patients (20 TMJs) were obtained and co-registered using two methods (non-guided and marker guided) using Mirada XD software (Mirada Medical Ltd, Oxford, UK). Three radiologists independently and blindly evaluated three types of images (MRI, CBCT and registered MRI-CBCT) at two times (T1 and T2) on two criteria: (1) quality of MRI-CBCT registrations (excellent, fair or poor) and (2) TMJ disc–condylar position and articular osseous abnormalities (osteophytes, erosions and subcortical cyst, surface flattening, sclerosis). Results: 75% of the non-guided registered images showed excellent quality, and 95% of the marker-guided registered images showed poor quality. Significant difference was found between the non-guided and marker-guided registration (χ2 = 108.5; p < 0.01). The interexaminer variability of the disc position in MRI [intraclass correlation coefficient (ICC) = 0.50 at T1, 0.56 at T2] was lower than that in MRI-CBCT registered images [ICC = 0.80 (0.52–0.92) at T1, 0.84 (0.62–0.93) at T2]. Erosions and subcortical cysts were noticed less frequently in the MRI-CBCT images than in CBCT images. Conclusions: Non-guided registration proved superior to marker-guided registration. Although MRI-CBCT fused images were slightly more limited than CBCT alone to detect osseous abnormalities, use of the fused images improved the consistency among examiners in detecting disc position in relation to the condyle. PMID:25734241

  8. The Role of Imaging for Trigeminal Neuralgia: A Segmental Approach to High-Resolution MRI.

    PubMed

    Seeburg, Daniel P; Northcutt, Benjamin; Aygun, Nafi; Blitz, Ari M

    2016-07-01

    High-resolution MRI affords exquisite anatomic detail and allows radiologists to scrutinize the entire course of the trigeminal nerve (cranial nerve [CN] V). This article focuses first on the normal MRI appearance of the course of CN V and how best to image each segment. Special attention is then devoted to the role of MRI in presurgical evaluation of patients with neurovascular conflict and in identifying secondary causes of trigeminal neuralgia, including multiple sclerosis. Fundamental concepts in postsurgical imaging after neurovascular decompression are also addressed. Finally, how imaging has been used to better understand the etiology of trigeminal neuralgia is discussed. PMID:27324998

  9. Recent Advances in the Imaging Diagnosis of Hepatocellular Carcinoma: Value of Gadoxetic Acid-Enhanced MRI

    PubMed Central

    Joo, Ijin; Lee, Jeong Min

    2016-01-01

    Magnetic resonance imaging (MRI) using gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DPTA), or gadoxetic acid for short, is a hepatocyte-specific contrast agent which is now increasingly used for the detection and characterization of focal hepatic lesions, particularly in patients at high-risk of developing hepatocellular carcinomas (HCC). In fact, several recent guidelines now recognize gadoxetic acid-enhanced MRI (Gd-EOB-MRI) as the primary diagnostic imaging modality for the noninvasive diagnosis of HCC, although it must be noted that several major guidelines still include only extracellular contrast media-enhanced computed tomography and MRI. The primary merits of Gd-EOB-MRI lie in the fact that it can provide not only dynamic imaging, but also hepatobiliary phase (HBP) imaging which can lead to high lesion-to-liver contrast and give additional information regarding hepatocyte uptake via organic anion transporting polypeptides. This, in turn, allows higher sensitivity in detecting small HCCs and helps provide additional information regarding the multistep process of hepatocarcinogenesis. Indeed, many recent studies have investigated the diagnostic value of Gd-EOB-MRI for early HCCs as well as its role as a potential imaging biomarker in predicting outcome. We herein review the recent advances in the imaging diagnosis of HCCs focusing on the applications of Gd-EOB-MRI and the challenging issues that remain. PMID:26989660

  10. Recent Advances in the Imaging Diagnosis of Hepatocellular Carcinoma: Value of Gadoxetic Acid-Enhanced MRI.

    PubMed

    Joo, Ijin; Lee, Jeong Min

    2016-02-01

    Magnetic resonance imaging (MRI) using gadolinium ethoxybenzyl diethylenetriamine pentaacetic acid (Gd-EOB-DPTA), or gadoxetic acid for short, is a hepatocyte-specific contrast agent which is now increasingly used for the detection and characterization of focal hepatic lesions, particularly in patients at high-risk of developing hepatocellular carcinomas (HCC). In fact, several recent guidelines now recognize gadoxetic acid-enhanced MRI (Gd-EOB-MRI) as the primary diagnostic imaging modality for the noninvasive diagnosis of HCC, although it must be noted that several major guidelines still include only extracellular contrast media-enhanced computed tomography and MRI. The primary merits of Gd-EOB-MRI lie in the fact that it can provide not only dynamic imaging, but also hepatobiliary phase (HBP) imaging which can lead to high lesion-to-liver contrast and give additional information regarding hepatocyte uptake via organic anion transporting polypeptides. This, in turn, allows higher sensitivity in detecting small HCCs and helps provide additional information regarding the multistep process of hepatocarcinogenesis. Indeed, many recent studies have investigated the diagnostic value of Gd-EOB-MRI for early HCCs as well as its role as a potential imaging biomarker in predicting outcome. We herein review the recent advances in the imaging diagnosis of HCCs focusing on the applications of Gd-EOB-MRI and the challenging issues that remain. PMID:26989660

  11. 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

  12. The role of MRI in diagnostic imaging of the injured knee

    SciTech Connect

    Stull, M.A.; Nelson, M.C. )

    1990-02-01

    Clinical evaluation of the acutely injured knee is often supplemented by radiographic studies. Magnetic resonance imaging (MRI) is rapidly replacing other techniques as the study of choice for evaluating knee injuries. MRI can delineate meniscal tears, cruciate and collateral ligament injuries, and tendon, capsule and cartilage problems.

  13. Hyperpolarized 129Xe MRI: A Viable Functional Lung Imaging Modality?

    PubMed Central

    Patz, Samuel; Hersman, F. William; Muradian, Iga; Hrovat, Mirko I.; Ruset, Iulian C.; Ketel, Stephen; Jacobson, Francine; Topulos, George P.; Hatabu, Hiroto; Butler, James P.

    2008-01-01

    The majority of researchers investigating hyperpolarized gas MRI as a candidate functional lung imaging modality have used 3He as their imaging agent of choice rather than 129Xe. This preference has been predominantly due to, 3He providing stronger signals due to higher levels of polarization and higher gyromagnetic ratio, as well as its being easily available to more researchers due to availability of polarizers (USA) or ease of gas transport (Europe). Most researchers agree, however, that hyperpolarized 129Xe will ultimately emerge as the imaging agent of choice due to its unlimited supply in nature and its falling cost. Our recent polarizer technology delivers vast improvements in hyperpolarized 129Xe output. Using this polarizer, we have demonstrated the unique property of xenon to measure alveolar surface area noninvasively. In this article, we describe our human protocols and their safety, and our results for the measurement of the partial pressure of pulmonary oxygen (pO2) by observation of 129Xe signal decay. We note that the measurement of pO2 by observation of 129Xe signal decay is more complex than that for 3He because of an additional signal loss mechanism due to interphase diffusion of 129Xe from alveolar gas spaces to septal tissue. This results in measurements of an equivalent pO2 that accounts for both traditional T1 decay from pO2 and that from interphase diffusion. We also provide an update on new technological advancements that form the foundation for an improved compact design polarizer as well as improvements that provide another order-of-magnitude scale-up in xenon polarizer output. PMID:17890035

  14. 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

  15. Multimodal in vivo MRI and NIRF imaging of bladder tumor using peptide conjugated glycol chitosan nanoparticles

    NASA Astrophysics Data System (ADS)

    Key, Jaehong; Dhawan, Deepika; Knapp, Deborah W.; Kim, Kwangmeyung; Kwon, Ick Chan; Choi, Kuiwon; Leary, James F.

    2012-03-01

    Exact detection and complete removal of cancer is a key point to minimize cancer recurrence. However, it is currently very difficult to detect small tumors inside human body and continuously monitor tumors using a non-invasive imaging modality. Presently, positron emission tomography (PET) can provide the most sensitive cancer images in the human body. However, PET imaging has very limited imaging time because they typically use isotopes with short halflives. PET imaging cannot also visualize anatomical information. Magnetic resonance imaging (MRI) can provide highresolution images inside the body but it has a low sensitivity, so MRI contrast agents are necessary to enhance the contrast of tumor. Near infrared fluorescent (NIRF) imaging has a good sensitivity to visualize tumor using optical probes, but it has a very limited tissue penetration depth. Therefore, we developed multi-modality nanoparticles for MRI based diagnosis and NIRF imaging based surgery of cancer. We utilized glycol chitosan of 350 nm as a vehicle for MRI contrast agents and NIRF probes. The glycol chitosan nanoparticles were conjugated with NIRF dye, Cy5.5 and bladder cancer targeting peptides to increase the internalization of cancer. For MR contrast effects, iron oxide based 22 nm nanocubes were physically loaded into the glycol chitosan nanoparticles. The nanoparticles were characterized and evaluated in bladder tumor bearing mice. Our study suggests the potential of our nanoparticles by both MRI and NIRF imaging for tumor diagnosis and real-time NIRF image-guided tumor surgery.

  16. ALARA in pediatric interventional and fluoroscopic imaging: striving to keep radiation doses as low as possible during fluoroscopy of pediatric patients--a white paper executive summary.

    PubMed

    Strauss, Keith J; Kaste, Sue C

    2006-09-01

    Pediatric patients might be as much as 10 times more radiosensitive than adults. Thus, adherence to the principle of "As low as reasonably achievable" (ALARA) represents a practice mandate that minimizes ionizing radiation exposure while optimizing imaging results. This symposium is the third multidisciplinary program that focused on the ALARA principle in pediatric imaging and addressed issues associated with pediatric fluoroscopy and interventional imaging techniques. PMID:17412149

  17. 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. PMID:27362339

  18. 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.

  19. 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.

  20. A comparison of five standard methods for evaluating image intensity uniformity in partially parallel imaging MRI

    PubMed Central

    Goerner, Frank L.; Duong, Timothy; Stafford, R. Jason; Clarke, Geoffrey D.

    2013-01-01

    Purpose: To investigate the utility of five different standard measurement methods for determining image uniformity for partially parallel imaging (PPI) acquisitions in terms of consistency across a variety of pulse sequences and reconstruction strategies. Methods: Images were produced with a phantom using a 12-channel head matrix coil in a 3T MRI system (TIM TRIO, Siemens Medical Solutions, Erlangen, Germany). Images produced using echo-planar, fast spin echo, gradient echo, and balanced steady state free precession pulse sequences were evaluated. Two different PPI reconstruction methods were investigated, generalized autocalibrating partially parallel acquisition algorithm (GRAPPA) and modified sensitivity-encoding (mSENSE) with acceleration factors (R) of 2, 3, and 4. Additionally images were acquired with conventional, two-dimensional Fourier imaging methods (R = 1). Five measurement methods of uniformity, recommended by the American College of Radiology (ACR) and the National Electrical Manufacturers Association (NEMA) were considered. The methods investigated were (1) an ACR method and a (2) NEMA method for calculating the peak deviation nonuniformity, (3) a modification of a NEMA method used to produce a gray scale uniformity map, (4) determining the normalized absolute average deviation uniformity, and (5) a NEMA method that focused on 17 areas of the image to measure uniformity. Changes in uniformity as a function of reconstruction method at the same R-value were also investigated. Two-way analysis of variance (ANOVA) was used to determine whether R-value or reconstruction method had a greater influence on signal intensity uniformity measurements for partially parallel MRI. Results: Two of the methods studied had consistently negative slopes when signal intensity uniformity was plotted against R-value. The results obtained comparing mSENSE against GRAPPA found no consistent difference between GRAPPA and mSENSE with regard to signal intensity uniformity

  1. Integrated megavoltage portal imaging with a 1.5 T MRI linac

    NASA Astrophysics Data System (ADS)

    Raaymakers, B. W.; de Boer, J. C. J.; Knox, C.; Crijns, S. P. M.; Smit, K.; Stam, M. K.; van den Bosch, M. R.; Kok, J. G. M.; Lagendijk, J. J. W.

    2011-10-01

    In this note, the feasibility of complementing our hybrid 1.5 T MRI linac (MRL) with a megavoltage (MV) portal imager is investigated. A standard aSi MV detector panel is added to the system and both qualitative and quantitative performances are determined. Simultaneous MR imaging and transmission imaging can be performed without mutual interference. The MV image quality is compromised by beam transmission and longer isocentre distance; still, the field edges and bony anatomy can be detected at very low dose levels of 0.4 cGy. MV imaging integrated with the MRL provides an independent and well-established position verification tool, a field edge check and a calibration for alignment of the coordinate systems of the MRI and the accelerator. The portal imager can also be a valuable means for benchmarking MRI-guided position verification protocols on a patient-specific basis in the introductory phase.

  2. [MRI, geometric distortion of the image and stereotaxy].

    PubMed

    Derosier, C; Delegue, G; Munier, T; Pharaboz, C; Cosnard, G

    1991-01-01

    The MRI technology may be the starting-point of geometric distorsion. The mathematical preciseness of a spatial location may be disturbed and alter the guidance of an MRI interventionnal act, especially in stereotactic brain biopsy. A review of the literature shows errors of 1 to 1.5 mm. Our results show an error of 0.16 +/- 0.66 mm. The control of quality: homogeneity and calibration of magnetic-field gradients, permit an improve of the balistic preciseness and give permission to realize the guidance of a stereotactic brain biopsy with the alone MRI. PMID:1880779

  3. Retroperitoneal nodular fasciitis: magnetic resonance imaging (MRI) and pathological features.

    PubMed

    Meduri; Zuiani; Del Frate C; Bazzocchi

    1998-07-01

    A case of pelvic nodular fasciitis, with particular reference to its peculiar radiological and pathological features is described. Only a few cases of pelvic nodular fasciitis are reported in the English literature and at the best of our knowledge, this is the first case of retroperitoneal origin. This report discusses the role of MRI in the characterization of soft tissue masses. No specific MRI findings of nodular fasciitis were identified and MRI doesn't add any contribution to the differential diagnosis between benign and malignant lesions. As a consequence, the histopathological examination is necessary for a definitive diagnosis. PMID:10358366

  4. Diagnostic imaging strategy for MDCT- or MRI-detected breast lesions: use of targeted sonography

    PubMed Central

    2012-01-01

    Background Leading-edge technology such as magnetic resonance imaging (MRI) or computed tomography (CT) often reveals mammographically and ultrasonographically occult lesions. MRI is a well-documented, effective tool to evaluate these lesions; however, the detection rate of targeted sonography varies for MRI detected lesions, and its significance is not well established in diagnostic strategy of MRI detected lesions. We assessed the utility of targeted sonography for multidetector-row CT (MDCT)- or MRI-detected lesions in practice. Methods We retrospectively reviewed 695 patients with newly diagnosed breast cancer who were candidates for breast conserving surgery and underwent MDCT or MRI in our hospital between January 2004 and March 2011. Targeted sonography was performed in all MDCT- or MRI-detected lesions followed by imaging-guided biopsy. Patient background, histopathology features and the sizes of the lesions were compared among benign, malignant and follow-up groups. Results Of the 695 patients, 61 lesions in 56 patients were detected by MDCT or MRI. The MDCT- or MRI-detected lesions were identified by targeted sonography in 58 out of 61 lesions (95.1%). Patients with pathological diagnoses were significantly older and more likely to be postmenopausal than the follow-up patients. Pathological diagnosis proved to be benign in 20 cases and malignant in 25. The remaining 16 lesions have been followed up. Lesion size and shape were not significantly different among the benign, malignant and follow-up groups. Conclusions Approximately 95% of MDCT- or MRI-detected lesions were identified by targeted sonography, and nearly half of these lesions were pathologically proven malignancies in this study. Targeted sonography is a useful modality for MDCT- or MRI-detected breast lesions. PMID:22691539

  5. MRI

    MedlinePlus

    ... an imaging test that uses powerful magnets and radio waves to create pictures of the body. It does ... be studied. These help send and receive the radio waves, and improve the quality of the images. During ...

  6. Automatic detection of multiple and overlapping EP catheters in fluoroscopic sequences.

    PubMed

    Milletari, Fausto; Navab, Nassir; Fallavollita, Pascal

    2013-01-01

    We propose a method to perform automatic detection of electrophysiology (EP) catheters in fluoroscopic sequences. Our approach does not need any initialization, is completely automatic, and can detect an arbitrary number of catheters at the same time. The method is based on the usage of blob detectors and clustering in order to detect all catheter electrodes, overlapping or not, within the X-ray images. The proposed technique is validated on 1422 fluoroscopic images yielding a tip detection rate of 99.3% and mean distance of 0.5mm from manually labeled ground truth centroids for all electrodes. PMID:24505783

  7. 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.

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

    PubMed

    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. PMID:23588215

  9. Major mouse placental compartments revealed by diffusion-weighted MRI, contrast-enhanced MRI, and fluorescence imaging

    PubMed Central

    Solomon, Eddy; Avni, Reut; Hadas, Ron; Raz, Tal; Garbow, Joel Richard; Bendel, Peter; Frydman, Lucio; Neeman, Michal

    2014-01-01

    Mammalian models, and mouse studies in particular, play a central role in our understanding of placental development. Magnetic resonance imaging (MRI) could be a valuable tool to further these studies, providing both structural and functional information. As fluid dynamics throughout the placenta are driven by a variety of flow and diffusion processes, diffusion-weighted MRI could enhance our understanding of the exchange properties of maternal and fetal blood pools—and thereby of placental function. These studies, however, have so far been hindered by the small sizes, the unavoidable motions, and the challenging air/water/fat heterogeneities, associated with mouse placental environments. The present study demonstrates that emerging methods based on the spatiotemporal encoding (SPEN) of the MRI information can robustly overcome these obstacles. Using SPEN MRI in combination with albumin-based contrast agents, we analyzed the diffusion behavior of developing placentas in a cohort of mice. These studies successfully discriminated the maternal from the fetal blood flows; the two orders of magnitude differences measured in these fluids’ apparent diffusion coefficients suggest a nearly free diffusion behavior for the former and a strong flow-based component for the latter. An intermediate behavior was observed by these methods for a third compartment that, based on maternal albumin endocytosis, was associated with trophoblastic cells in the interphase labyrinth. Structural features associated with these dynamic measurements were consistent with independent intravital and ex vivo fluorescence microscopy studies and are discussed within the context of the anatomy of developing mouse placentas. PMID:24969421

  10. Major mouse placental compartments revealed by diffusion-weighted MRI, contrast-enhanced MRI, and fluorescence imaging.

    PubMed

    Solomon, Eddy; Avni, Reut; Hadas, Ron; Raz, Tal; Garbow, Joel Richard; Bendel, Peter; Frydman, Lucio; Neeman, Michal

    2014-07-15

    Mammalian models, and mouse studies in particular, play a central role in our understanding of placental development. Magnetic resonance imaging (MRI) could be a valuable tool to further these studies, providing both structural and functional information. As fluid dynamics throughout the placenta are driven by a variety of flow and diffusion processes, diffusion-weighted MRI could enhance our understanding of the exchange properties of maternal and fetal blood pools--and thereby of placental function. These studies, however, have so far been hindered by the small sizes, the unavoidable motions, and the challenging air/water/fat heterogeneities, associated with mouse placental environments. The present study demonstrates that emerging methods based on the spatiotemporal encoding (SPEN) of the MRI information can robustly overcome these obstacles. Using SPEN MRI in combination with albumin-based contrast agents, we analyzed the diffusion behavior of developing placentas in a cohort of mice. These studies successfully discriminated the maternal from the fetal blood flows; the two orders of magnitude differences measured in these fluids' apparent diffusion coefficients suggest a nearly free diffusion behavior for the former and a strong flow-based component for the latter. An intermediate behavior was observed by these methods for a third compartment that, based on maternal albumin endocytosis, was associated with trophoblastic cells in the interphase labyrinth. Structural features associated with these dynamic measurements were consistent with independent intravital and ex vivo fluorescence microscopy studies and are discussed within the context of the anatomy of developing mouse placentas. PMID:24969421

  11. A technique to consider mismatches between fMRI and EEG/MEG sources for fMRI-constrained EEG/MEG source imaging: a preliminary simulation study

    NASA Astrophysics Data System (ADS)

    Im, Chang-Hwan; Lee, Soo Yeol

    2006-12-01

    fMRI-constrained EEG/MEG source imaging can be a powerful tool in studying human brain functions with enhanced spatial and temporal resolutions. Recent studies on the combination of fMRI and EEG/MEG have suggested that fMRI prior information could be readily implemented by simply imposing different weighting factors to cortical sources overlapping with the fMRI activations. It has been also reported, however, that such a hard constraint may cause severe distortions or elimination of meaningful EEG/MEG sources when there are distinct mismatches between the fMRI activations and the EEG/MEG sources. If one wants to obtain the actual EEG/MEG source locations and uses the fMRI prior information as just an auxiliary tool to enhance focality of the distributed EEG/MEG sources, it is reasonable to weaken the strength of fMRI constraint when severe mismatches between fMRI and EEG/MEG sources are observed. The present study suggests an efficient technique to automatically adjust the strength of fMRI constraint according to the mismatch level. The use of the proposed technique rarely affects the results of conventional fMRI-constrained EEG/MEG source imaging if no major mismatch between the two modalities is detected; while the new results become similar to those of typical EEG/MEG source imaging without fMRI constraint if the mismatch level is significant. A preliminary simulation study using realistic EEG signals demonstrated that the proposed technique can be a promising tool to selectively apply fMRI prior information to EEG/MEG source imaging.

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

    PubMed

    Sanders, Linda M; Daigle, Megan

    2016-03-01

    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. PMID:26684050

  13. Combined analysis of sMRI and fMRI imaging data provides accurate disease markers for hearing impairment.

    PubMed

    Tan, Lirong; Chen, Ye; Maloney, Thomas C; Caré, Marguerite M; Holland, Scott K; Lu, Long J

    2013-01-01

    In this research, we developed a robust two-layer classifier that can accurately classify normal hearing (NH) from hearing impaired (HI) infants with congenital sensori-neural hearing loss (SNHL) based on their Magnetic Resonance (MR) images. Unlike traditional methods that examine the intensity of each single voxel, we extracted high-level features to characterize the structural MR images (sMRI) and functional MR images (fMRI). The Scale Invariant Feature Transform (SIFT) algorithm was employed to detect and describe the local features in sMRI. For fMRI, we constructed contrast maps and detected the most activated/de-activated regions in each individual. Based on those salient regions occurring across individuals, the bag-of-words strategy was introduced to vectorize the contrast maps. We then used a two-layer model to integrate these two types of features together. With the leave-one-out cross-validation approach, this integrated model achieved an AUC score of 0.90. Additionally, our algorithm highlighted several important brain regions that differentiated between NH and HI children. Some of these regions, e.g. planum temporale and angular gyrus, were well known auditory and visual language association regions. Others, e.g. the anterior cingulate cortex (ACC), were not necessarily expected to play a role in differentiating HI from NH children and provided a new understanding of brain function and of the disorder itself. These important brain regions provided clues about neuroimaging markers that may be relevant to the future use of functional neuroimaging to guide predictions about speech and language outcomes in HI infants who receive a cochlear implant. This type of prognostic information could be extremely useful and is currently not available to clinicians by any other means. PMID:24363991

  14. Temporomandibular joint arthrography: a comparison between a fluoroscopic and a nonfluoroscopic technique

    SciTech Connect

    Benson, B.W.; Langlais, R.P.; Abramovitch, K.

    1989-05-01

    A nonfluoroscopic temporomandibular joint arthrographic technique is contrasted with a more widely employed fluoroscopically guided technique. The nonfluoroscopic technique uses a posterior approach to joint injection, as contrasted with the lateral injection approach of the fluoroscopically guided technique. The advantages of the nonfluoroscopic technique are less radiation dose to the patient, less expensive and less sophisticated imaging equipment, and less potential for neurovascular trauma. The fluoroscopic technique offers greater control of the procedure, less patient and operator time, and the capability for a dynamic videofluoroscopic study. Both techniques appear to be safe and efficacious. Differences in anatomy, imaging modalities, patient radiation exposure, and potential complications are also discussed as part of this comparison.48 references.

  15. A similarity retrieval method for functional magnetic resonance imaging (fMRI) statistical maps

    NASA Astrophysics Data System (ADS)

    Tungaraza, R. F.; Guan, J.; Rolfe, S.; Atmosukarto, I.; Poliakov, A.; Kleinhans, N. M.; Aylward, E.; Ojemann, J.; Brinkley, J. F.; Shapiro, L. G.

    2009-02-01

    We propose a method for retrieving similar fMRI statistical images given a query fMRI statistical image. Our method thresholds the voxels within those images and extracts spatially distinct regions from the voxels that remain. Each region is defined by a feature vector that contains the region centroid, the region area, the average activation value for all the voxels within that region, the variance of those activation values, the average distance of each voxel within that region to the region's centroid, and the variance of the voxel's distance to the region's centroid. The similarity between two images is obtained by the summed minimum distance of their constituent feature vectors. Results on a dataset of fMRI statistical images from experiments involving distinct cognitive tasks are shown.

  16. Human vision model for the objective evaluation of perceived image quality applied to MRI and image restoration

    NASA Astrophysics Data System (ADS)

    Salem, Kyle A.; Wilson, David L.

    2002-12-01

    We are developing a method to objectively quantify image quality and applying it to the optimization of interventional magnetic resonance imaging (iMRI). In iMRI, images are used for live-time guidance of interventional procedures such as the minimally invasive treatment of cancer. Hence, not only does one desire high quality images, but they must also be acquired quickly. In iMRI, images are acquired in the Fourier domain, or k-space, and this allows many creative ways to image quickly such as keyhole imaging where k-space is preferentially subsampled, yielding suboptimal images at very high frame rates. Other techniques include spiral, radial, and the combined acquisition technique. We have built a perceptual difference model (PDM) that incorporates various components of the human visual system. The PDM was validated using subjective image quality ratings by naive observers and task-based measures defined by interventional radiologists. Using the PDM, we investigated the effects of various imaging parameters on image quality and quantified the degradation due to novel imaging techniques. Results have provided significant information about imaging time versus quality tradeoffs aiding the MR sequence engineer. The PDM has also been used to evaluate other applications such as Dixon fat suppressed MRI and image restoration. In image restoration, the PDM has been used to evaluate the Generalized Minimal Residual (GMRES) image restoration method and to examine the ability to appropriately determine a stopping condition for such iterative methods. The PDM has been shown to be an objective tool for measuring image quality and can be used to determine the optimal methodology for various imaging applications.

  17. Understanding and using fluoroscopic dose display information.

    PubMed

    Weinberg, Brent D; Guild, Jeffrey B; Arbique, Gary M; Chason, David P; Anderson, Jon A

    2015-01-01

    Fluoroscopically guided procedures are an area of radiology in which radiation exposure to the patient is highly operator dependent. Modern fluoroscopy machines display a variety of information, including technique factors, field of view, operating geometry, exposure mode, fluoroscopic time, air kerma at the reference point (RAK), and air kerma area-product. However, the presentation of this information is highly vendor specific, and many users are unaware of how to interpret this information and use it to perform a study with the minimum necessary dose. A conceptual framework for understanding the radiation dose readout during a procedure is to compare it to the dashboard of an automobile, where the rate at which radiation is being applied (the RAK rate [mGy/min]) is the dose "speed" and the cumulative amount of radiation applied (cumulative RAK [mGy]) is the dose "odometer." This analogy can be used as a starting point to improve knowledge of these parameters, including how RAK is measured, how RAK correlates with skin dose, and how parameters are displayed differently during fluoroscopy and fluorography. Awareness of these factors is critical to understanding how dose parameters translate to patient risk and the consequences of high-dose studies. With this increased awareness, physicians performing fluoroscopically guided procedures can understand how to use built-in features of the fluoroscopic equipment (pulse rate, beam filtration, and automatic exposure control) and fluoroscopic techniques (procedure planning, patient positioning, proper collimation, and magnification) to reduce patient radiation dose, thereby improving patient safety. PMID:25442356

  18. Development of a geometrically accurate imaging protocol at 3 Tesla MRI for stereotactic radiosurgery treatment planning

    NASA Astrophysics Data System (ADS)

    Zhang, B.; MacFadden, D.; Damyanovich, A. Z.; Rieker, M.; Stainsby, J.; Bernstein, M.; Jaffray, D. A.; Mikulis, D.; Ménard, C.

    2010-11-01

    The purpose of this study is to develop a geometrically accurate imaging protocol at 3 T magnetic resonance imaging (MRI) for stereotactic radiosurgery (SRS) treatment planning. In order to achieve this purpose, a methodology is developed to investigate the geometric accuracy and stability of 3 T MRI for SRS in phantom and patient evaluations. Forty patients were enrolled on a prospective clinical trial. After frame placement prior to SRS, each patient underwent 3 T MRI after 1.5 T MRI and CT. MR imaging protocols included a T1-weighted gradient echo sequence and a T2-weighted spin echo sequence. Phantom imaging was performed on 3 T prior to patient imaging using the same set-up and imaging protocols. Geometric accuracy in patients and phantoms yielded comparable results for external fiducial reference deviations and internal landmarks between 3 T and 1.5 T MRI (mean <=0.6 mm; standard deviation <=0.3 mm). Mean stereotactic reference deviations between phantoms and patients correlated well (T1: R = 0.79; T2: R = 0.84). Statistical process control analysis on phantom QA data demonstrated the stability of our SRS imaging protocols, where the geometric accuracy of the 3 T SRS imaging protocol is operating within the appropriate tolerance. Our data provide evidence supporting the spatial validity of 3 T MRI for targeting SRS under imaging conditions investigated. We have developed a systematic approach to achieve confidence on the geometric integrity of a given imaging system/technique for clinical integration in SRS application.

  19. 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

  20. 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.

  1. PET/MRI: THE NEXT GENERATION OF MULTI-MODALITY IMAGING?

    PubMed Central

    Pichler, Bernd; Wehrl, Hans F; Kolb, Armin; Judenhofer, Martin S

    2009-01-01

    Multi-modal imaging is now well-established in routine clinical practice. Especially in the field of Nuclear Medicine, new PET installations are comprised almost exclusively of combined PET/CT scanners rather than PET-only systems. However, PET/CT has certain notable shortcomings, including the inability to perform simultaneous data acquisition and the significant radiation dose to the patient contributed by CT. MRI offers, compared to CT, better contrast among soft tissues as well as functional-imaging capabilities. Therefore, the combination of PET with MRI provides many advantages which go far beyond simply combining functional PET information with structural MRI information. Many technical challenges, including possible interference between these modalities, have to be solved when combining PET and MRI and various approaches have been adapted to resolving these issues. Here we present an overview of current working prototypes of combined PET/MRI scanners from different groups. In addition, besides PET/MR images of mice, the first such images of a rat PET/MR, acquired with the first commercial clinical PET/MRI scanner, are presented. The combination of PET and MR is a promising tool in pre-clinical research and will certainly progress to clinical application. PMID:18396179

  2. Tracing and quantification of pharmaceuticals using MR imaging and spectroscopy at clinical MRI system

    NASA Astrophysics Data System (ADS)

    Jeong, Eun-Kee; Liu, Xin; Shi, Xianfeng; Yu, Y. Bruce; Lu, Zeng-Rong

    2012-10-01

    Magnetic resonance imaging (MRI) and spectroscopy (MRS) is very powerful modality for imaging and localized investigation of biological tissue. Medical MRI measures nuclear magnetization of the water protons, which consists of 70 % of our body. MRI provides superior contrast among different soft tissues to all other existing medical imaging modalities, including ultrasound, X-ray CT, PET, and SPECT. In principle, MRI/S may be an ideal non-invasive tool for drug delivery research. However, because of its low sensitivity, a large dose is required for tracing pharmaceuticals. Therefore, its use for imaging of pharmaceuticals is very limited mostly to molecules that contain a paramagnetic metal ion, such as gadolinium (Gd3+) and manganese (Mn2+). The paramagnetic metal ion provides a large fluctuating magnetic field at the proton in the water molecule via a coordinate site. The measurement of local drug concentration is the first step for further quantification. Local concentration of the paramagnetic-ion based MRI contrast agent can be indirectly measured via the change in the water signal intensity. 19F MRI/S of fluorinated complex may be an option for drug delivery and tracing agent, because the fluorinated molecule may be directly detected due to its large magnetic moment (94 % of proton) and 100 % abundance.

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

    PubMed

    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

  4. Three-dimensional reconstruction of registered and fused Chinese Visible Human and patient MRI images.

    PubMed

    Li, L; Liu, Y X; Song, Z J

    2006-04-01

    Radiological images are commonly used as important tools in medical diagnoses and treatment. Different modalities of medical images provide uniquely different content. Hence, it is natural and desirable to combine different image modalities to obtain additional new information to enhance clinical assessment. However, given the current technology, radiological images are not always sufficiently informative to permit diagnosis and treatment. In order to address this problem, we fused selected portions of the Chinese Visible Human (CVH) dataset with MRI images from a patient. Specifically, we segmented the caudate nucleus, the lentiform nucleus, and the thalamus in the CVH dataset and then registered and fused this dataset with corresponding MRI images using both rigid and nonrigid registration techniques. After rigid and nonrigid registration, the CVH and MRI images largely coincided with each other. The shape, relationship, and position of focal areas and neural structures were clearly displayed. Using volume and surface rendering, these images were three-dimensionally reconstructed to display the neural structures of interest within the brain. These structures can be rotated at will and observed from different angles. Our research indicates that the fusion of CVH and patients' MRI images can enhance the amount of neural information available to physicians and lay a foundation for the clinical use of the CVH dataset. PMID:16506210

  5. Electrical tissue property imaging using MRI at dc and Larmor frequency

    NASA Astrophysics Data System (ADS)

    Seo, Jin Keun; Kim, Dong-Hyun; Lee, Joonsung; In Kwon, Oh; Sajib, Saurav Z. K.; Woo, Eung Je

    2012-08-01

    Cross-sectional imaging of conductivity and permittivity distributions inside the human body has been actively investigated in impedance imaging areas such as electrical impedance tomography (EIT) and magnetic induction tomography (MIT). Since the conductivity and permittivity values exhibit frequency-dependent changes, it is worthwhile to perform spectroscopic imaging from almost dc to hundreds of MHz. To probe the human body, we may inject current using surface electrodes or induce current using external coils. In EIT and MIT, measured data are only available on the boundary or exterior of the body unless we invasively place sensors inside the body. Their image reconstruction problems are nonlinear and ill-posed to result in images with a relatively low spatial resolution. Noting that an MRI scanner can noninvasively measure magnetic fields inside the human body, electrical tissue property imaging methods using MRI have lately been proposed. Magnetic resonance EIT (MREIT) performs conductivity imaging at dc or below 1 kHz by externally injecting current into the human body and measuring induced internal magnetic flux density data using an MRI scanner. Magnetic resonance electrical property tomography (MREPT) produces both conductivity and permittivity images at the Larmor frequency of an MRI scanner based on B1-mapping techniques. Since internal data are only available in MREIT and MREPT, we may formulate well-posed inverse problems for image reconstructions. To develop related imaging techniques, we should clearly understand the basic principles of MREIT and MREPT, which are based on coupled physics of bioelectromagnetism and MRI as well as associated mathematical methods. In this paper, we describe the physical principles of MREIT and MREPT in a unified way and associate measurable quantities with the conductivity and permittivity. Clarifying the key relations among them, we examine existing image reconstruction algorithms to reveal their capabilities and

  6. Learning Computational Models of Video Memorability from fMRI Brain Imaging.

    PubMed

    Han, Junwei; Chen, Changyuan; Shao, Ling; Hu, Xintao; Han, Jungong; Liu, Tianming

    2015-08-01

    Generally, various visual media are unequally memorable by the human brain. This paper looks into a new direction of modeling the memorability of video clips and automatically predicting how memorable they are by learning from brain functional magnetic resonance imaging (fMRI). We propose a novel computational framework by integrating the power of low-level audiovisual features and brain activity decoding via fMRI. Initially, a user study experiment is performed to create a ground truth database for measuring video memorability and a set of effective low-level audiovisual features is examined in this database. Then, human subjects' brain fMRI data are obtained when they are watching the video clips. The fMRI-derived features that convey the brain activity of memorizing videos are extracted using a universal brain reference system. Finally, due to the fact that fMRI scanning is expensive and time-consuming, a computational model is learned on our benchmark dataset with the objective of maximizing the correlation between the low-level audiovisual features and the fMRI-derived features using joint subspace learning. The learned model can then automatically predict the memorability of videos without fMRI scans. Evaluations on publically available image and video databases demonstrate the effectiveness of the proposed framework. PMID:25314715

  7. 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

  8. 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.

  9. [Imaging of acute pancreatitis--the role of US, CT and MRI].

    PubMed

    Ishihara, Takeshi; Yamaguchi, Taketo; Saisho, Hiromitsu

    2004-11-01

    Imaging of the pancreas with US and CT plays a major role in the diagnosis and evaluations of patients with acute pancreatitis. In severe acute pancreatitis, dynamic CT is essential to assess the severity of the disease and evaluate the complications. MRI is comparable to CT in its capacity to provide precise information about the severity of acute pancreatitis. MRI has some advantages over CT in being free from ionizing radiation and lower toxity of gadolinium which is used for contrast medium intravenously. The disadvantages of MRI, however, include cost, longer exam duration, limited availability and the practical difficulties of scanning a patient with ICU equipment. PMID:15552887

  10. Multispectral image classification of MRI data using an empirically-derived clustering algorithm

    SciTech Connect

    Horn, K.M.; Osbourn, G.C.; Bouchard, A.M.; Sanders, J.A. |

    1998-08-01

    Multispectral image analysis of magnetic resonance imaging (MRI) data has been performed using an empirically-derived clustering algorithm. This algorithm groups image pixels into distinct classes which exhibit similar response in the T{sub 2} 1st and 2nd-echo, and T{sub 1} (with ad without gadolinium) MRI images. The grouping is performed in an n-dimensional mathematical space; the n-dimensional volumes bounding each class define each specific tissue type. The classification results are rendered again in real-space by colored-coding each grouped class of pixels (associated with differing tissue types). This classification method is especially well suited for class volumes with complex boundary shapes, and is also expected to robustly detect abnormal tissue classes. The classification process is demonstrated using a three dimensional data set of MRI scans of a human brain tumor.

  11. 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.

  12. MRI and FDG-PET/CT imaging in gynecological malignancies: the radiation oncology perspective.

    PubMed

    Fennell, Jamina; Scholber, Jutta; Grosu, Anca L; Volegova-Neher, Natalja; Henne, Karl; Langer, Mathias; Meyer, Philipp T; Gitsch, Gerald; Bartl, Nico

    2016-06-01

    MRI and FDG-PET imaging plays an important role in diagnosis, monitoring and follow-up of gynecological cancer. The goal of this paper was to summarize data of the literature about sensitivity and specificity of MRI and FDG-PET/CT for detection of primary tumor, lymph nodes invasion and metastases in cervix and endometrial cancer and to discuss their implication for radiation treatment planning and monitoring. PMID:26957003

  13. 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.

  14. Current and future diagnostic tools for traumatic brain injury: CT, conventional MRI, and diffusion tensor imaging.

    PubMed

    Brody, David L; Mac Donald, Christine L; Shimony, Joshua S

    2015-01-01

    Brain imaging plays a key role in the assessment of traumatic brain injury. In this review, we present our perspectives on the use of computed tomography (CT), conventional magnetic resonance imaging (MRI), and newer advanced modalities such as diffusion tensor imaging. Specifically, we address assessment for immediately life-threatening intracranial lesions (noncontrast head CT), assessment of progression of intracranial lesions (noncontrast head CT), documenting intracranial abnormalities for medicolegal reasons (conventional MRI with blood-sensitive sequences), presurgical planning for post-traumatic epilepsy (high spatial resolution conventional MRI), early prognostic decision making (conventional MRI with diffusion-weighted imaging), prognostic assessment for rehabilitative planning (conventional MRI and possibly diffusion tensor imaging in the future), stratification of subjects and pharmacodynamic tracking of targeted therapies in clinical trials (specific MRI sequences or positron emission tomography (PET) ligands, e.g., diffusion tensor imaging for traumatic axonal injury). We would like to emphasize that all of these methods, especially the newer research approaches, require careful radiologic-pathologic validation for optimal interpretation. We have taken this approach in a mouse model of pericontusional traumatic axonal injury. We found that the extent of reduction in the diffusion tensor imaging parameter relative anisotropy directly correlated with the number of amyloid precursor protein (APP)-stained axonal varicosities (r(2)=0.81, p<0.0001, n=20 injured mice). Interestingly, however, the least severe contusional injuries did not result in APP-stained axonal varicosities, but did cause reduction in relative anisotropy. Clearly, both the imaging assessments and the pathologic assessments will require iterative refinement. PMID:25702222

  15. 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.

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

    PubMed

    Yan, Jianhua; Lim, Jason Chu-Shern; 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 (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. PMID:25575248

  17. Leg MRI scan

    MedlinePlus

    ... imaging - leg; Magnetic resonance imaging - lower extremity; MRI - ankle; Magnetic resonance imaging - ankle; MRI - femur; MRI - leg ... or bone scan Birth defects of the leg, ankle, or foot Bone pain and fever Broken bone ...

  18. Hybrid Utrasound and MRI Acquisitions for High-Speed Imaging of Respiratory Organ Motion

    PubMed Central

    Preiswerk, Frank; Toews, Matthew; Hoge, W. Scott; Chiou, Jr-yuan George; Panych, Lawrence P.; Wells, William M.; Madore, Bruno

    2016-01-01

    Magnetic Resonance (MR) imaging provides excellent image quality at a high cost and low frame rate. Ultrasound (US) provides poor image quality at a low cost and high frame rate. We propose an instance-based learning system to obtain the best of both worlds: high quality MR images at high frame rates from a low cost single-element US sensor. Concurrent US and MRI pairs are acquired during a relatively brief offine learning phase involving the US transducer and MR scanner. High frame rate, high quality MR imaging of respiratory organ motion is then predicted from US measurements, even after stopping MRI acquisition, using a probabilistic kernel regression framework. Experimental results show predicted MR images to be highly representative of actual MR images. PMID:27135063

  19. 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

  20. Perceptual difference paradigm for analyzing image quality of fast MRI techniques

    NASA Astrophysics Data System (ADS)

    Wilson, David L.; Salem, Kyle A.; Huo, Donglai; Duerk, Jeffrey L.

    2003-05-01

    We are developing a method to objectively quantify image quality and applying it to the optimization of fast magnetic resonance imaging methods. In MRI, to capture the details of a dynamic process, it is critical to have both high temporal and spatial resolution. However, there is typically a trade-off between the two, making the sequence engineer choose to optimize imaging speed or spatial resolution. In response to this problem, a number of different fast MRI techniques have been proposed. To evaluate different fast MRI techniques quantitatively, we use a perceptual difference model (PDM) that incorporates various components of the human visual system. The PDM was validated using subjective image quality ratings by naive observers and task-based measures as defined by radiologists. Using the PDM, we investigated the effects of various imaging parameters on image quality and quantified the degradation due to novel imaging techniques including keyhole, keyhole Dixon fat suppression, and spiral imaging. Results have provided significant information about imaging time versus quality tradeoffs aiding the MR sequence engineer. The PDM has been shown to be an objective tool for measuring image quality and can be used to determine the optimal methodology for various imaging applications.

  1. High resolution MRI imaging at 1. 5T using surface coils

    SciTech Connect

    Blinder, R.A.; Herfkens, R.J.; Coleman, R.E.; Johnson, G.A.; Schenck, J.F.; Hart, H.R. Jr.; Foster, T.H.; Edelstein, W.A.

    1985-05-01

    The potential utility of high resolution MRI imaging in various pathologic conditions was explored. As the voxel size of MRI images is decreased the signal per pixel diminishes due to the geometric decrease in volume. In very high resolution images the signal can be small enough to be obscured by Johnson noise. High magnetic field strength (1.5T) coupled with surface coil imaging increases the signal to noise ratio. The surface coils used were single turn coils with diameters of 6 or 11 cm depending on the body part being imaged. A ''clam shell'' crossed coil was used for imaging the knees. Using a 1.5T prototype MRI imaging system we have obtained images with 14.5 cm field of view that are 256 by 256 pixels with a slice thickness of 3 mm. Good signal to noise is obtained using 2DTF imaging with only 2 excitations per phase encoding step (1 average). Images obtained of peripheral joints demonstrate articular cartilage, ligamentous structures, and trabeculae in medullary bone. These exams have demonstrated the changes of rheumatoid arthritis, and the extent of neoplastic involvement in bone. Images of the temporomandibular joint and the neck have been obtained. Parathyroid adenomas have been identified. Surface coil imaging and high magnetic fields allow for high resolution MRI imaging of various anatomic structures. Good signal to noise can be accomplished without extensive signal averaging so that reasonable imaging times and throughput can be realized with voxel dimensions of 0.6 x 0.6 x 3mm.

  2. A physical comparison of a fluoroscopic CAT system and the EMI head scanner. [Computerized Axial Tomograms

    NASA Technical Reports Server (NTRS)

    Baily, N. A.; Keller, R. A.

    1976-01-01

    A quantitative comparison of the capabilities to produce computerized tomograms was made between the EMI head scanner and reconstructions from images provided by a large screen low light level-TV camera fluoroscopic system. A phantom made from lucite containing rods of various materials and sizes was used. The computer printout of each was analyzed and a correlation of 0.8 was noted between the results of both systems. The differential attenuation detectability of the fluoroscopic system was found to be comparable to or better than the EMI unit. As expected from a consideration of the quantum statistics for each system, the noise in the obtained reconstructions was also comparable. It is concluded that such a fluoroscopic system performs favorably when compared to the presently available commercial systems.

  3. Magnetic resonance imaging (MRI) detection of the murine brain response to light: temporal differentiation and negative functional MRI changes.

    PubMed Central

    Huang, W; Plyka, I; Li, H; Eisenstein, E M; Volkow, N D; Springer, C S

    1996-01-01

    Using a 9.4 T MRI instrument, we have obtained images of the mouse brain response to photic stimulation during a period between deep anesthesia and the early stages of arousal. The large image enhancements we observe (often >30%) are consistent with literature results extrapolated to 9.4 T. However, there are also two unusual aspects to our findings. (i) The visual area of the brain responds only to changes in stimulus intensity, suggesting that we directly detect operations of the M visual system pathway. Such a channel has been observed in mice by invasive electrophysiology, and described in detail for primates. (ii) Along with the typical positive response in the area of the occipital portion of the brain containing the visual cortex, another area displays decreased signal intensity upon stimulation. Images Fig. 1 Fig. 4 PMID:8650215

  4. Surveillance imaging in children with malignant CNS tumors: low yield of spine MRI.

    PubMed

    Perreault, Sébastien; Lober, Robert M; Carret, Anne-Sophie; Zhang, Guohua; Hershon, Linda; Décarie, Jean-Claude; Vogel, Hannes; Yeom, Kristen W; Fisher, Paul G; Partap, Sonia

    2014-02-01

    Magnetic resonance imaging (MRI) is routinely obtained in patients with central nervous system (CNS) tumors, but few studies have been conducted to evaluate this practice. We assessed the benefits of surveillance MRI and more specifically spine MRI in a contemporary cohort. We evaluated MRI results of children diagnosed with CNS tumors from January 2000 to December 2011. Children with at least one surveillance MRI following the diagnosis of medulloblastoma (MB), atypical teratoid rhabdoid tumor (ATRT), pineoblastoma (PB), supratentorial primitive neuroectodermal tumor, supratentorial high-grade glioma (World Health Organization grade III-IV), CNS germ cell tumors or ependymoma were included. A total of 2,707 brain and 1,280 spine MRI scans were obtained in 258 patients. 97% of all relapses occurred in the brain and 3% were isolated to the spine. Relapse was identified in 226 (8%) brain and 48 (4%) spine MRI scans. The overall rate of detecting isolated spinal relapse was 9/1,000 and 7/1,000 for MB patients. MRI performed for PB showed the highest rate for detecting isolated spinal recurrence with 49/1,000. No initial isolated spinal relapse was identified in patients with glioma, supratentorial primitive neuroectodermal tumor and ATRT. Isolated spinal recurrences are infrequent in children with malignant CNS tumors and the yield of spine MRI is very low. Tailoring surveillance spine MRI to patients with higher spinal relapse risk such as PB, MB with metastatic disease and within 3 years of diagnosis could improve allocation of resources without compromising patient care. PMID:24401959

  5. 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.

  6. 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. PMID:27394165

  7. 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.

  8. 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.

  9. 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. PMID:25915977

  10. 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.

  11. Intrapelvic obturator internus muscle injections: a novel fluoroscopic technique.

    PubMed

    Valovska, Assia; Zaccagnino, Michael P; Weaver, Michael J; Valovski, Ivan; Kaye, Alan David; Urman, Richard D

    2015-01-01

    The obturator internus (OI) muscle is important in adult chronic noninfectious pelvic, perineal, gluteal, and retrotrochanteric pain syndromes. Evaluation and management of these patients' pain can be challenging because of the complex anatomy of this region, broad differential diagnosis, and lack of specific physical examination findings. Consequently, several clinicians have advocated the use of image guided injections to assist in the accurate diagnosis of OI-related symptoms and provide symptomatic relief to affected patients. We present 2 case series describing a novel fluoroscopically guided contrast controlled transpectineal approach to intrapelvic OI injections. Unlike prior fluoroscopically guided OI injection techniques, the approach described in the present 2 cases utilized multiple standard pelvic views, thus facilitating optimal needle positioning in three-dimensional space. This technique utilized standard fluoroscopic pelvic views to accurately measure needle depth within the pelvic cavity permitting the bulk of the OI to be injected in a controlled and safe fashion. The first patient underwent a left intrapelvic OI muscle injection with bupivacaine 0.25% and 40 mg methylprednisolone. The average pre- and postprocedural visual analog pain scale scores were 5 out of 10 and 2 out of 10, respectively, with a self-reported 75% pain reduction. The second patient underwent a right intrapelvic OI muscle injection with bupivacaine 0.25% and 40 mg methylprednisolone. The average pre- and postprocedural visual analog scale scores were 8 out of 10 and 1 out of 10, respectively, with a self-reported 90% pain reduction. Larger scale studies should be undertaken to evaluate the therapeutic efficacy and generalized accuracy of this technique. PMID:25794225

  12. Use of the Microangiographic Fluoroscope for Coiling of Intracranial Aneurysms

    PubMed Central

    Binning, Mandy J.; Orion, David; Yashar, Parham; Webb, Sharon; Ionita, Ciprian N.; Jain, Amit; Rudin, Stephen; Hopkins, L. Nelson; Siddiqui, Adnan H.; Levy, Elad I.

    2013-01-01

    BACKGROUND Neurointervention is an ever-evolving specialty with tools including microcatheters, microwires, and coils that allow treatment of pathological conditions in increasingly smaller intracranial arteries, requiring increasing accuracy. As endovascular tools evolve, so too should the imaging. OBJECTIVE To detail the use of microangiography performed with a novel fluoroscope during coiling of intracranial aneurysms in 2 separate patients and discuss the benefits and potential limitations of the technology. METHODS The microangiographic fluoroscope (MAF) is an ultra high-resolution x-ray detector with superior resolution over a small field of view. The MAF can be incorporated into a standard angiographic C-arm system for use during endovascular procedures. RESULTS The MAF was useful for improved visualization during endovascular coiling of 2 unruptured intracranial aneurysms, without adding significant time to the procedure. No significant residual aneurysm filling was identified post-coiling, and no complications occurred. CONCLUSION The MAF is a high-resolution detector developed for use in neurointerventional cases in which superior image quality over a small field of view is required. It has been used with success for coiling of 2 unruptured aneurysms at our institution. It shows promise as an important tool in improving the accuracy with which neurointerventionists can perform certain intracranial procedures. PMID:21694658

  13. 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. PMID:27451338

  14. 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.

  15. Foundations of MRI phase imaging and processing for Quantitative Susceptibility Mapping (QSM).

    PubMed

    Schweser, Ferdinand; Deistung, Andreas; Reichenbach, Jürgen R

    2016-03-01

    Quantitative Susceptibility Mapping (QSM) is a novel MRI based technique that relies on estimates of the magnetic field distribution in the tissue under examination. Several sophisticated data processing steps are required to extract the magnetic field distribution from raw MRI phase measurements. The objective of this review article is to provide a general overview and to discuss several underlying assumptions and limitations of the pre-processing steps that need to be applied to MRI phase data before the final field-to-source inversion can be performed. Beginning with the fundamental relation between MRI signal and tissue magnetic susceptibility this review covers the reconstruction of magnetic field maps from multi-channel phase images, background field correction, and provides an overview of state of the art QSM solution strategies. PMID:26702760

  16. MRI Scans

    MedlinePlus

    Magnetic resonance imaging (MRI) uses a large magnet and radio waves to look at organs and structures inside your body. Health care professionals use MRI scans to diagnose a variety of conditions, from torn ...

  17. Magnetic resonance imaging (MRI) in the diagnosis of head and neck disease.

    PubMed

    Supsupin, Emilio P; Demian, Nagi M

    2014-05-01

    Magnetic resonance imaging (MRI) is the modality of choice to identify intracranial or perineural spread from a head and neck primary tumor. Perineural spread is a form of metastatic disease in which primary tumors spread along neural pathways. Orbital cellulitis is a sight-threatening, and potentially life-threatening condition. Urgent imaging is performed to assess the anatomic extent of disease, including postseptal, cavernous sinus, and intracranial involvement, and identify orbital abscesses that require exploration and drainage. MRI is useful in the evaluation of the brachial plexus. PMID:24794270

  18. Dual-Modal Nanoprobes for Imaging of Mesenchymal Stem Cell Transplant by MRI and Fluorescence Imaging

    PubMed Central

    Hong, Kyung Ah; Lin, Shunmei; Lee, Yuwon; Cha, Jinmyung; Lee, Jin-Kyu; Hong, Cheol Pyo; Han, Bong Soo; Jung, Sung Il; Kim, Seung Hyup; Yoon, Kang Sup

    2009-01-01

    Objective To determine the feasibility of labeling human mesenchymal stem cells (hMSCs) with bifunctional nanoparticles and assessing their potential as imaging probes in the monitoring of hMSC transplantation. Materials and Methods The T1 and T2 relaxivities of the nanoparticles (MNP@SiO2[RITC]-PEG) were measured at 1.5T and 3T magnetic resonance scanner. Using hMSCs and the nanoparticles, labeling efficiency, toxicity, and proliferation were assessed. Confocal laser scanning microscopy and transmission electron microscopy were used to specify the intracellular localization of the endocytosed iron nanoparticles. We also observed in vitro and in vivo visualization of the labeled hMSCs with a 3T MR scanner and optical imaging. Results MNP@SiO2(RITC)-PEG showed both superparamagnetic and fluorescent properties. The r1 and r2 relaxivity values of the MNP@SiO2(RITC)-PEG were 0.33 and 398 mM-1 s-1 at 1.5T, respectively, and 0.29 and 453 mM-1 s-1 at 3T, respectively. The effective internalization of MNP@SiO2(RITC)-PEG into hMSCs was observed by confocal laser scanning fluorescence microscopy. The transmission electron microscopy images showed that MNP@SiO2(RITC)-PEG was internalized into the cells and mainly resided in the cytoplasm. The viability and proliferation of MNP@SiO2(RITC)-PEG-labeled hMSCs were not significantly different from the control cells. MNP@SiO2(RITC)-PEG-labeled hMSCs were observed in vitro and in vivo with optical and MR imaging. Conclusion MNP@SiO2(RITC)-PEG can be a useful contrast agent for stem cell imaging, which is suitable for a bimodal detection by MRI and optical imaging. PMID:19885318

  19. Ex-PRESS glaucoma filter: an MRI compatible metallic orbital foreign body imaged at 1.5 and 3 T

    PubMed Central

    Mabray, M.C.; Uzelac, A.; Talbott, J.F.; Lin, S.C.; Gean, A.D.

    2015-01-01

    AIM To report on the MRI compatibility of the Ex-PRESS glaucoma filtration device, a tiny metallic implant placed into the anterior chamber of the eye that is much smaller than traditional glaucoma shunts, and to educate the radiology community regarding its appearance. MATERIALS AND METHODS Seven patients with Ex-PRESS glaucoma filtration devices were identified that had undergone MRI at San Francisco General Hospital/University of California San Francisco Medical Center by searching and cross-referencing the radiology reporting system and the electronic medical record. MRI images were reviewed for artefact interfering with interpretation. Ophthalmology examinations were reviewed for evidence of complications. RESULTS Eighteen individual MRI examinations were performed during 12 unique MRI events on these 7 patients. 13/18 individual MRI examinations and 7/12 MRI events were performed at 3 T with the others performed at 1.5 T. Mean time from Ex-PRESS implantation to MRI was 17.5 months. Mean time from MRI to first ophthalmology examination was 1.1 months and from MRI to latest ophthalmology examination was 6.6 months. Susceptibility artefact did not interfere with image interpretation and no complications related to MRI were encountered. CONCLUSION The Ex-PRESS glaucoma filtration device appears to be safe for MRI at 1.5 and 3 T and does not produce significant susceptibility artefact to affect diagnostic interpretation adversely. PMID:25735675

  20. 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

  1. Development of a PET scanner for simultaneously imaging small animals with MRI and PET.

    PubMed

    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

  2. Magnetic resonance imaging (MRI) detection of the murine brain response to light: Temporal differentiation and negative functional MRI changes

    SciTech Connect

    Huang, Wei; Palyka, I.; Li, HaiFang

    1996-06-11

    Using a 9.4 T MRI instrument, we have obtained images of the mouse brain response to photic stimulation during a period between deep anesthesia and the early stages of arousal. The large image enhancements we observe (often >30%) are consistent with literature results extrapolated to 9.4 T. However, there are also two unusual aspects to our findings. (i) The visual area of the brain responds only to changes in stimulus intensity, suggesting that we directly detect operations of the M visual system pathway. Such a channel has been observed in mice by invasive electrophysiology, and described in detail for primates. (ii) Along with the typical positive response in the area of the occipital portion of the brain containing the visual cortex; another area displays decreased signal intensity upon stimulation. 41 refs., 4 figs.

  3. In Vivo Imaging of Stepwise Vessel Occlusion in Cerebral Photothrombosis of Mice by 19F MRI

    PubMed Central

    Kleinschnitz, Christoph; Kampf, Thomas; Jakob, Peter M.; Stoll, Guido

    2011-01-01

    Background 19F magnetic resonance imaging (MRI) was recently introduced as a promising technique for in vivo cell tracking. In the present study we compared 19F MRI with iron-enhanced MRI in mice with photothrombosis (PT) at 7 Tesla. PT represents a model of focal cerebral ischemia exhibiting acute vessel occlusion and delayed neuroinflammation. Methods/Principal Findings Perfluorocarbons (PFC) or superparamagnetic iron oxide particles (SPIO) were injected intravenously at different time points after photothrombotic infarction. While administration of PFC directly after PT induction led to a strong 19F signal throughout the entire lesion, two hours delayed application resulted in a rim-like 19F signal at the outer edge of the lesion. These findings closely resembled the distribution of signal loss on T2-weighted MRI seen after SPIO injection reflecting intravascular accumulation of iron particles trapped in vessel thrombi as confirmed histologically. By sequential administration of two chemically shifted PFC compounds 0 and 2 hours after illumination the different spatial distribution of the 19F markers (infarct core/rim) could be visualized in the same animal. When PFC were applied at day 6 the fluorine marker was only detected after long acquisition times ex vivo. SPIO-enhanced MRI showed slight signal loss in vivo which was much more prominent ex vivo indicative for neuroinflammation at this late lesion stage. Conclusion Our study shows that vessel occlusion can be followed in vivo by 19F and SPIO-enhanced high-field MRI while in vivo imaging of neuroinflammation remains challenging. The timing of contrast agent application was the major determinant of the underlying processes depicted by both imaging techniques. Importantly, sequential application of different PFC compounds allowed depiction of ongoing vessel occlusion from the core to the margin of the ischemic lesions in a single MRI measurement. PMID:22194810

  4. Nonrigid PET motion compensation in the lower abdomen using simultaneous tagged-MRI and PET imaging

    PubMed Central

    Guérin, B.; Cho, S.; Chun, S. Y.; Zhu, X.; Alpert, N. M.; El Fakhri, G.; Reese, T.; Catana, C.

    2011-01-01

    Purpose: We propose a novel approach for PET respiratory motion correction using tagged-MRI and simultaneous PET-MRI acquisitions.Methods: We use a tagged-MRI acquisition followed by motion tracking in the phase domain to estimate the nonrigid deformation of biological tissues during breathing. In order to accurately estimate motion even in the presence of noise and susceptibility artifacts, we regularize the traditional HARP tracking strategy using a quadratic roughness penalty on neighboring displacement vectors (R-HARP). We then incorporate the motion fields estimated with R-HARP in the system matrix of an MLEM PET reconstruction algorithm formulated both for sinogram and list-mode data representations. This approach allows reconstruction of all detected coincidences in a single image while modeling the effect of motion both in the emission and the attenuation maps. At present, tagged-MRI does not allow estimation of motion in the lungs and our approach is therefore limited to motion correction in soft tissues. Since it is difficult to assess the accuracy of motion correction approaches in vivo, we evaluated the proposed approach in numerical simulations of simultaneous PET-MRI acquisitions using the NCAT phantom. We also assessed its practical feasibility in PET-MRI acquisitions of a small deformable phantom that mimics the complex deformation pattern of a lung that we imaged on a combined PET-MRI brain scanner.Results: Simulations showed that the R-HARP tracking strategy accurately estimated realistic respiratory motion fields for different levels of noise in the tagged-MRI simulation. In simulations of tumors exhibiting increased uptake, contrast estimation was 20% more accurate with motion correction than without. Signal-to-noise ratio (SNR) was more than 100% greater when performing motion-corrected reconstruction which included all counts, compared to when reconstructing only coincidences detected in the first of eight gated frames. These results were

  5. Iterative Image Reconstruction for PROPELLER-MRI using the NonUniform Fast Fourier Transform

    PubMed Central

    Tamhane, Ashish A.; Anastasio, Mark A.; Gui, Minzhi; Arfanakis, Konstantinos

    2013-01-01

    Purpose To investigate an iterative image reconstruction algorithm using the non-uniform fast Fourier transform (NUFFT) for PROPELLER (Periodically Rotated Overlapping parallEL Lines with Enhanced Reconstruction) MRI. Materials and Methods Numerical simulations, as well as experiments on a phantom and a healthy human subject were used to evaluate the performance of the iterative image reconstruction algorithm for PROPELLER, and compare it to that of conventional gridding. The trade-off between spatial resolution, signal to noise ratio, and image artifacts, was investigated for different values of the regularization parameter. The performance of the iterative image reconstruction algorithm in the presence of motion was also evaluated. Results It was demonstrated that, for a certain range of values of the regularization parameter, iterative reconstruction produced images with significantly increased SNR, reduced artifacts, for similar spatial resolution, compared to gridding. Furthermore, the ability to reduce the effects of motion in PROPELLER-MRI was maintained when using the iterative reconstruction approach. Conclusion An iterative image reconstruction technique based on the NUFFT was investigated for PROPELLER MRI. For a certain range of values of the regularization parameter the new reconstruction technique may provide PROPELLER images with improved image quality compared to conventional gridding. PMID:20578028

  6. 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.

  7. Image Registration for Quantitative Analysis of Kidney Function using MRI

    NASA Astrophysics Data System (ADS)

    Sance, Rosario; Ledesma-Carbayo, María J.; Lundervold, Arvid; Santos, Andrés

    2006-10-01

    The aim of the present study is to analyze the possibilities of registration algorithms to compensate respiratory motion and deformation in abdominal DCE-MRI 3D temporary series. The final objective is that from registered data, appropriate intensity curves of local renal activity along the time could be represented for each kidney voxel. Assuming a relation between the voxel intensity and the contrast media concentration, this non-invasive renographic method could be used to evaluate the local renal function, and to calculate typical renal parameters like glomerular filtration rate.

  8. 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.

  9. Imaging Patterns in MRI in Recent Bone Injuries Following Negative or Inconclusive Plain Radiographs

    PubMed Central

    Sadineni, Raghu Teja; Bellapa, Narayan Chander; Velicheti, Sandeep

    2015-01-01

    Background Few bony injuries and most soft tissue injuries cannot be detected on plain radiography. Magnetic resonance imaging (MRI) can detect such occult bony injuries due to signal changes in bone marrow. In addition to excluding serious bony injuries, it can also identify tendon, ligament, cartilage and other soft tissue injuries and thus help in localizing the cause of morbidity. Aims and Objectives To determine the MRI imaging patterns in recent bone injuries (less than 4 weeks) following negative or inconclusive plain radiographs. To determine the role of MRI in recent fractures. Results Out of the 75 individuals with history of recent injury of less than 4 weeks duration, fracture line was demonstrated in 16 patients (21%) who had no obvious evidence of bone injury on plain radiographs. Bone contusion or bruising of the bone was demonstrated in 39 (52%) patients. This was the commonest abnormality detected in MRI. The remaining 20 patients did not show any obvious injury to the bone on MR imaging however, soft tissue injury could be demonstrated in 12 (16%) patients which show that the extent of soft tissue injury was relatively well demonstrated by MR imaging. The present study showed that occult injuries commonly occur at the Knee followed by Ankle, Wrist, Foot, Elbow, Leg, Hands, Hips & Spine. Conclusion The study showed that MR is efficient in the detection of occult bone injuries which are missed on radiography. Compared to radiographs, MRI clearly depicted the extent of injuries and associated soft tissue involvement. MRI demonstrates both acute and chronic injuries and also differentiates both, whereas radiography has poor sensitivity for acute injuries. Also, the soft tissue injuries like tendionous and ligamentous injuries cannot be identified on radiographs. PMID:26557590

  10. Symmetry-guided design and fluorous synthesis of a stable and rapidly excreted imaging tracer for (19)F MRI.

    PubMed

    Jiang, Zhong-Xing; Liu, Xin; Jeong, Eun-Kee; Yu, Yihua Bruce

    2009-01-01

    Getting FIT: A bispherical (19)F imaging tracer, (19)FIT, was designed and synthesized. (19)FIT is advantageous over perfluorocarbon-based (19)F imaging agents, as it is not retained in the organs and does not require complex formulation procedures. Imaging agents such as (19)FIT can lead to (19)F magnetic resonance imaging (MRI) playing an important role in drug therapy, analogous to the role played by (1)H MRI in disease diagnosis. PMID:19475598

  11. 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.

  12. Spatio-Temporal Multiscale Denoising of Fluoroscopic Sequence.

    PubMed

    Amiot, Carole; Girard, Catherine; Chanussot, Jocelyn; Pescatore, Jeremie; Desvignes, Michel

    2016-06-01

    In the past 20 years, a wide range of complex fluoroscopically guided procedures have shown considerable growth. Biologic effects of the exposure (radiation induced burn, cancer) lead to reduce the dose during the intervention, for the safety of patients and medical staff. However, when the dose is reduced, image quality decreases, with a high level of noise and a very low contrast. Efficient restoration and denoising algorithms should overcome this drawback. We propose a spatio-temporal filter operating in a multi-scales space. This filter relies on a first order, motion compensated, recursive temporal denoising. Temporal high frequency content is first detected and then matched over time to allow for a strong denoising in the temporal axis. We study this filter in the curvelet domain and in the dual-tree complex wavelet domain, and compare those results to state of the art methods. Quantitative and qualitative analysis on both synthetic and real fluoroscopic sequences demonstrate that the proposed filter allows a great dose reduction. PMID:26812705

  13. Non-invasive functional imaging of Cerebral Blood Volume with Vascular-Space-Occupancy (VASO) MRI

    PubMed Central

    Lu, Hanzhang; Hua, Jun; van Zijl, Peter C.M.

    2013-01-01

    Functional MRI (fMRI) based on changes in cerebral blood volume (CBV) can directly probe vasodilatation and vasoconstriction during brain activation or physiologic challenges, and can provide important insights into the mechanism of Blood-Oxygenation-Level-Dependent (BOLD) signal changes. At present, the most widely used CBV fMRI technique in humans is called Vascular-Space-Occupancy (VASO) MRI and this article provides a technical review of this method. VASO MRI utilizes T1 differences between blood and tissue to distinguish these two compartments within a voxel and uses blood-nulling inversion recovery sequence to yield an MR signal proportional to 1-CBV. As such, vasodilatation will result in a VASO signal decrease and vasoconstriction will have the reverse effect. The VASO technique can be performed dynamically with a temporal resolution comparable to several other fMRI methods such as BOLD or Arterial-Spin-Labeling (ASL), and is particularly powerful when conducted in conjunction with these complementary techniques. The pulse sequence and imaging parameters of VASO can be optimized such that the signal change is predominantly of CBV origin, but careful considerations should be taken to minimize other contributions, such as those from the BOLD effect, CBF, and CSF. Sensitivity of the VASO technique remains to be the primary disadvantage when compared to BOLD, but this technique is increasingly demonstrating utility in neuroscientific and clinical applications. PMID:23355392

  14. DCE-MRI in hepatocellular carcinoma-clinical and therapeutic image biomarker

    PubMed Central

    Chen, Bang-Bin; Shih, Tiffany Ting-Fang

    2014-01-01

    Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) enables tumor vascular physiology to be assessed. Within the tumor tissue, contrast agents (gadolinium chelates) extravasate from intravascular into the extravascular extracellular space (EES), which results in a signal increase on T1-weighted MRI. The rate of contrast agents extravasation to EES in the tumor tissue is determined by vessel leakiness and blood flow. Thus, the signal measured on DCE-MRI represents a combination of permeability and perfusion. The semi-quantitative analysis is based on the calculation of heuristic parameters that can be extracted from signal intensity-time curves. These enhancing curves can also be deconvoluted by mathematical modeling to extract quantitative parameters that may reflect tumor perfusion, vascular volume, vessel permeability and angiogenesis. Because hepatocellular carcinoma (HCC) is a hypervascular tumor, many emerging therapies focused on the inhibition of angiogenesis. DCE-MRI combined with a pharmacokinetic model allows us to produce highly reproducible and reliable parametric maps of quantitative parameters in HCC. Successful therapies change quantitative parameters of DCE-MRI, which may be used as early indicators of tumor response to anti-angiogenesis agents that modulate tumor vasculature. In the setting of clinical trials, DCE-MRI may provide relevant clinical information on the pharmacodynamic and biologic effects of novel drugs, monitor treatment response and predict survival outcome in HCC patients. PMID:24695624

  15. MRI Safety during Pregnancy

    MedlinePlus

    ... during the exam? Contrast material MRI during pregnancy Magnetic resonance imaging (MRI) If you are pregnant and your doctor wants to perform a magnetic resonance imaging (MRI) exam, there is a possibility that your ...

  16. Microvascular MRI and unsupervised clustering yields histology-resembling images in two rat models of glioma

    PubMed Central

    Coquery, Nicolas; Francois, Olivier; Lemasson, Benjamin; Debacker, Clément; Farion, Régine; Rémy, Chantal; Barbier, Emmanuel Luc

    2014-01-01

    Imaging heterogeneous cancer lesions is a real challenge. For diagnosis, histology often remains the reference, but it is widely acknowledged that biopsies are not reliable. There is thus a strong interest in establishing a link between clinical in vivo imaging and the biologic properties of tissues. In this study, we propose to construct histology-resembling images based on tissue microvascularization, a magnetic resonance imaging (MRI) accessible source of contrast. To integrate the large amount of information collected with microvascular MRI, we combined a manual delineation of a spatial region of interest with an unsupervised, model-based cluster analysis (Mclust). This approach was applied to two rat models of glioma (C6 and F98). Six MRI parameters were mapped: apparent diffusion coefficient, vessel wall permeability, cerebral blood volume fraction, cerebral blood flow, tissular oxygen saturation, and cerebral metabolic rate of oxygen. Five clusters, defined by their MRI features, were found to correspond to specific histologic features, and revealed intratumoral spatial structures. These results suggest that the presence of a cluster within a tumor can be used to assess the presence of a tissue type. In addition, the cluster composition, i.e., a signature of the intratumoral structure, could be used to characterize tumor models as histology does. PMID:24849664

  17. Copper oxide nanoparticles as contrast agents for MRI and ultrasound dual-modality imaging

    NASA Astrophysics Data System (ADS)

    Perlman, Or; Weitz, Iris S.; Azhari, Haim

    2015-08-01

    Multimodal medical imaging is gaining increased popularity in the clinic. This stems from the fact that data acquired from different physical phenomena may provide complementary information resulting in a more comprehensive picture of the pathological state. In this context, nano-sized contrast agents may augment the potential sensitivity of each imaging modality and allow targeted visualization of physiological points of interest (e.g. tumours). In this study, 7 nm copper oxide nanoparticles (CuO NPs) were synthesized and characterized. Then, in vitro and phantom specimens containing CuO NPs ranging from 2.4 to 320 μg · mL-1 were scanned, using both 9.4 T MRI and through-transmission ultrasonic imaging. The results show that the CuO NPs induce shortening of the magnetic T1 relaxation time on the one hand, and increase the speed of sound and ultrasonic attenuation coefficient on the other. Moreover, these visible changes are NP concentration-dependent. The change in the physical properties resulted in a substantial increase in the contrast-to-noise ratio (3.4-6.8 in ultrasound and 1.2-19.3 in MRI). In conclusion, CuO NPs are excellent candidates for MRI-ultrasound dual imaging contrast agents. They offer radiation-free high spatial resolution scans by MRI, and cost-effective high temporal resolution scans by ultrasound.

  18. 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

  19. A Feasibility Study of an Intravascular Imaging Antenna to Image Atherosclerotic Plaques in Swine Using 3.0 T MRI

    PubMed Central

    Zhang, Chen; Zhao, Lei; Ma, Xiaohai; Zhang, Zhaoqi; Fan, Zhanming

    2014-01-01

    Purpose To investigate the feasibility of an intravascular imaging antenna to image abdominal aorta atherosclerotic plaque in swine using 3.0T magnetic resonance imaging (MRI). Methods Atherosclerotic model was established in 6 swine. After 8 months, swine underwent an MR examination, which was performed using an intravascular imaging guide-wire, and images of the common iliac artery and the abdominal aorta were acquired. Intravascular ultrasound (IVUS) was performed in the right femoral artery; images at the same position as for the MR examination were obtained. The luminal border and external elastic membrane of the targeted arteries were individually drawn in the MR and IVUS images. After co-registering these images, the vessel, lumen, and vessel wall areas and the plaque burden in the same lesions imaged using different modalities were calculated and compared. The diagnostic accuracy of intravascular MR examination in delineating the vessel wall and detecting plaques were analyzed and compared using IVUS. Results Compared with IVUS, good agreement was found between MRI and IVUS for delineating vessel, lumen, and vessel wall areas and plaque burden (r value: 0.98, 0.95, 0.96 and 0.91, respectively; P<0.001). Conclusion Compared with IVUS, using an intravascular imaging guide-wire to image deep seated arteries allowed determination of the vessel, lumen and vessel wall areas and plaque size and burden. This may provide an alternative method for detecting atherosclerotic plaques in the future. PMID:25259585

  20. Atlas-registration based image segmentation of MRI human thigh muscles in 3D space

    NASA Astrophysics Data System (ADS)

    Ahmad, Ezak; Yap, Moi Hoon; Degens, Hans; McPhee, Jamie S.

    2014-03-01

    Automatic segmentation of anatomic structures of magnetic resonance thigh scans can be a challenging task due to the potential lack of precisely defined muscle boundaries and issues related to intensity inhomogeneity or bias field across an image. In this paper, we demonstrate a combination framework of atlas construction and image registration methods to propagate the desired region of interest (ROI) between atlas image and the targeted MRI thigh scans for quadriceps muscles, femur cortical layer and bone marrow segmentations. The proposed system employs a semi-automatic segmentation method on an initial image in one dataset (from a series of images). The segmented initial image is then used as an atlas image to automate the segmentation of other images in the MRI scans (3-D space). The processes include: ROI labeling, atlas construction and registration, and morphological transform correspondence pixels (in terms of feature and intensity value) between the atlas (template) image and the targeted image based on the prior atlas information and non-rigid image registration methods.

  1. 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

  2. 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.

  3. Statistical fractal border features for MRI breast mass images

    NASA Astrophysics Data System (ADS)

    Penn, Alan I.; Bolinger, Lizann; Loew, Murray H.

    1998-06-01

    MRI has been proposed as an alternative method to mammography for detecting and staging breast cancer. Recent studies have shown that architectural features of breast masses may be useful in improving specificity. Since fractal dimension (fd) has been correlated with roughness, and border roughness is an indicator of malignancy, the fd of the mass border is a promising architectural feature for achieving improved specificity. Previous methods of estimating the fd of the mass border have been unreliable because of limited data or overlay restrictive assumptions of the fractal model. We present preliminary results of a statistical approach in which a sample space of fd estimates is generated from a family of self-affine fractal models. The fd of the mass border is then estimated from the statistics of the sample space.

  4. Small BODIPY Probes for Combined Dual (19) F MRI and Fluorescence Imaging.

    PubMed

    Huynh, Anh Minh; Müller, Andreas; Kessler, Sonja M; Henrikus, Sarah; Hoffmann, Caroline; Kiemer, Alexandra K; Bücker, Arno; Jung, Gregor

    2016-07-19

    The combination of the two complementary imaging modalities (19) F magnetic resonance imaging (MRI) and fluorescence imaging (FLI) possesses high potential for biological and medical applications. Herein we report the first design, synthesis, dual detection validation, and cytotoxic testing of four promising BODIPY dyes for dual (19) F MRI-fluorescence detection. Using straightforward Steglich reactions, small fluorinated alcohols were easily covalently tethered to a BODIPY dye in high yields, leaving its fluorescence properties unaffected. The synthesized compounds were analyzed with various techniques to demonstrate their potential utility in dual imaging. As expected, the chemically and magnetically equivalent trifluoromethyl groups of the agents exhibited a single NMR signal. The determined longitudinal relaxation times T1 and the transverse relaxation times T2 , both in the lower second range, enabled the imaging of four compounds in vitro. The most auspicious dual (19) F MRI-fluorescence agent was also successfully imaged in a mouse post-mortem within a 9.4 T small-animal tomograph. Toxicological assays with human cells (primary HUVEC and HepG2 cell line) also indicated the possibility for animal testing. PMID:27347843

  5. Posture-Dependent Human 3He Lung Imaging in an Open Access MRI System: Initial Results

    PubMed Central

    Tsai, L. L.; Mair, R. W.; Li, C.-H.; Rosen, M. S.; Patz, S.; Walsworth, R. L.

    2008-01-01

    Rationale and Objectives The human lung and its functions are extremely sensitive to orientation and posture, and debate continues as to the role of gravity and the surrounding anatomy in determining lung function and heterogeneity of perfusion and ventilation. However, study of these effects is difficult. The conventional high-field magnets used for most hyperpolarized 3He MRI of the human lung, and most other common radiological imaging modalities including PET and CT, restrict subjects to lying horizontally, minimizing most gravitational effects. Materials and Methods In this paper, we briefly review the motivation for posture-dependent studies of human lung function, and present initial imaging results of human lungs in the supine and vertical body orientations using inhaled hyperpolarized 3He gas and an open-access MRI instrument. The open geometry of this MRI system features a “walk-in” capability that permits subjects to be imaged in vertical and horizontal positions, and potentially allows for complete rotation of the orientation of the imaging subject in a two-dimensional plane. Results Initial results include two-dimensional lung images acquired with ~ 4 × 8 mm in-plane resolution and three-dimensional images with ~ 2 cm slice thickness. Conclusion Effects of posture variation are observed, including posture-related effects of the diaphragm and distension of the lungs while vertical. PMID:18486009

  6. 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

  7. [Radiation exposure from shoe-fitting fluoroscopes].

    PubMed

    Busch, Uwe

    2015-03-01

    It is 40 years ago that a very popular X-ray device disappeared in German shoe shops: the shoe-fitting fluoroscope or Pedoskop. Since the 1930s, these X-ray machines were an integral part of any good shoe business. Following the entry into force X-Ray Regulation (RöV 1973) the use of these devices was prohibited in Germany. PMID:25023417

  8. 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. PMID:26973263

  9. MRI and FDG PET/CT imaging manifestations of cardiac sarcoidosis.

    PubMed

    Lu, Yang; Sweiss, Nadera J

    2015-12-01

    A 52-year-old man had biopsy-proven sarcoidosis of mediastinal lymph nodes. Cardiac sarcoidosis was confirmed on cardiac MRI with typical imaging features as delayed gadolinium enhancement. Follow-up FDG PET/CT with a 3-day pretest diet modification showed suppression of overall myocardial uptake of FDG but with multifocal abnormal FDG uptake in the myocardium regions corresponding to the previous MRI findings. Additional noncardiac active sarcoidosis involving multiple organ and lymph nodes were also visualized on FDG PET/CT. PMID:26544904

  10. Managing uncertainty in complex interventional fluoroscopic procedures.

    PubMed

    Leuenberger, Ronald; Meade, Jason A

    2014-11-01

    There was a concern for potential patient skin burns indicated by air kerma as recorded by fluoroscopy equipment during two interventional fluoroscopic procedures. Two sentinel events as defined by The Joint Commission were indicated. Dose reconstruction based on measurements of machine output showed the air kerma readings were high by approximately a factor of four and no patient injury or sentinel event occurred. The radiation safety program in effect at the time of the incidents allowed discovery of equipment problems before a serious patient injury occurred, but additional controls have been implemented as a result, including quality control checks performed by cardiology, additional training, a database for tracking equipment maintenance, and mandatory entry of patient dose into electronic health records with follow-up orders automatically generated by the electronic health records. Most unexpected injuries are a result of multiple failures, but there are also multiple opportunities to prevent the injury. This paper provides a comprehensive look at patient safety concerns during two interventional cardiology fluoroscopic procedures and offers ways to further reduce risks to patients. It focuses on lessons learned and a systems-based approach to improving and promoting radiation safety during complex interventional fluoroscopic procedures. PMID:25272028

  11. Registration of structurally dissimilar images in MRI-based brachytherapy

    NASA Astrophysics Data System (ADS)

    Berendsen, F. F.; Kotte, A. N. T. J.; de Leeuw, A. A. C.; Jürgenliemk-Schulz, I. M.; Viergever, M. A.; Pluim, J. P. W.

    2014-08-01

    A serious challenge in image registration is the accurate alignment of two images in which a certain structure is present in only one of the two. Such topological changes are problematic for conventional non-rigid registration algorithms. We propose to incorporate in a conventional free-form registration framework a geometrical penalty term that minimizes the volume of the missing structure in one image. We demonstrate our method on cervical MR images for brachytherapy. The intrapatient registration problem involves one image in which a therapy applicator is present and one in which it is not. By including the penalty term, a substantial improvement in the surface distance to the gold standard anatomical position and the residual volume of the applicator void are obtained. Registration of neighboring structures, i.e. the rectum and the bladder is generally improved as well, albeit to a lesser degree.

  12. Imaging Oxygen Metabolism In Acute Stroke Using MRI

    PubMed Central

    An, Hongyu; Ford, Andria L.; Vo, Katie D.; Liu, Qingwei; Chen, Yasheng; Lee, Jin-Moo; Lin, Weili

    2014-01-01

    The ability to image the ischemic penumbra during hyper-acute stroke promises to identify patients who may benefit from treatment intervention beyond population-defined therapeutic time windows. MR blood oxygenation level dependent (BOLD) contrast imaging has been explored in ischemic stroke. This review provides an overview of several BOLD-based methods, including susceptibility weighted imaging (SWI), R2, R2*, R2′, R2* under oxygen challenge, MR_OEF and MROMI approaches to assess cerebral oxygen metabolism in ischemic stroke. We will review the underlying pathophysiological basis of the imaging approaches, followed by a brief introduction of BOLD contrast. Finally, we will discuss the applications of the BOLD approaches in patients with ischemic stroke. BOLD-based methods hold promise for imaging tissue oxygenation during acute ischemia. Further technical refinement and validation studies in stroke patients against positron emission tomography (PET) measurements are needed. PMID:24707451

  13. Determining Microvascular Obstruction and Infarct Size with Steady-State Free Precession Imaging Cardiac MRI

    PubMed Central

    Wuest, Wolfgang; Lell, Michael; May, Matthias; Scharf, Michael; Schlundt, Christian; Achenbach, Stephan; Uder, Michael; Schmid, Axel

    2015-01-01

    Purpose In cardiac MRI (cMRI) injection of contrast medium may be performed prior to the acquisition of cine steady-state free precession (SSFP) imaging to speed up the protocol and avoid delay before late Gadolinium enhancement (LGE) imaging. Aim of this study was to evaluate whether a condensed clinical protocol with contrast cine SSFP imaging is able to detect early microvascular obstruction (MO) and determine the infarct size compared to the findings of LGE inversion recovery sequences. Materials and Methods The study complies with the Declaration of Helsinki and was performed following approval by the ethic committee of the University of Erlangen-Nuremberg. Written informed consent was obtained from every patient. 68 consecutive patients (14 females/54 males) with acute ST-elevation myocardial infarction (STEMI) treated by percutaneous coronary revascularization were included in this study. CMRI was performed 6.6±2 days after symptom onset and MO and infarct size in early contrast SSFP cine imaging were compared to LGE imaging. Results MO was detected in 47/68 (69%) patients on cine SSFP and in 41/68 (60%) patients on LGE imaging. In 6 patients MO was found on cine SSFP imaging but was not detectable on LGE imaging. Infarct size on cine SSFP showed a strong agreement to LGE imaging (intraclass correlation coefficient [ICC] of 0.96 for enddiastolic, p<0.001 and 0.96 for endsystolic, p<0.001 respectively). Significant interobserver agreement was found measuring enddiastolic and endsystolic infarct size on cine SSFP imaging (p<0.01). Conclusions In patients after STEMI infarct size and presence of MO can be detected with contrast cine SSFP imaging. This could be an option in patients who are limited in their ability to comply with the demands of a cMRI protocol. PMID:25793609

  14. 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

  15. SPECT data acquisition and image reconstruction in a stationary small animal SPECT/MRI system

    NASA Astrophysics Data System (ADS)

    Xu, Jingyan; Chen, Si; Yu, Jianhua; Meier, Dirk; Wagenaar, Douglas J.; Patt, Bradley E.; Tsui, Benjamin M. W.

    2010-04-01

    The goal of the study was to investigate data acquisition strategies and image reconstruction methods for a stationary SPECT insert that can operate inside an MRI scanner with a 12 cm bore diameter for simultaneous SPECT/MRI imaging of small animals. The SPECT insert consists of 3 octagonal rings of 8 MR-compatible CZT detectors per ring surrounding a multi-pinhole (MPH) collimator sleeve. Each pinhole is constructed to project the field-of-view (FOV) to one CZT detector. All 24 pinholes are focused to a cylindrical FOV of 25 mm in diameter and 34 mm in length. The data acquisition strategies we evaluated were optional collimator rotations to improve tomographic sampling; and the image reconstruction methods were iterative ML-EM with and without compensation for the geometric response function (GRF) of the MPH collimator. For this purpose, we developed an analytic simulator that calculates the system matrix with the GRF models of the MPH collimator. The simulator was used to generate projection data of a digital rod phantom with pinhole aperture sizes of 1 mm and 2 mm and with different collimator rotation patterns. Iterative ML-EM reconstruction with and without GRF compensation were used to reconstruct the projection data from the central ring of 8 detectors only, and from all 24 detectors. Our results indicated that without GRF compensation and at the default design of 24 projection views, the reconstructed images had significant artifacts. Accurate GRF compensation substantially improved the reconstructed image resolution and reduced image artifacts. With accurate GRF compensation, useful reconstructed images can be obtained using 24 projection views only. This last finding potentially enables dynamic SPECT (and/or MRI) studies in small animals, one of many possible application areas of the SPECT/MRI system. Further research efforts are warranted including experimentally measuring the system matrix for improved geometrical accuracy, incorporating the co

  16. 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. PMID:26523656

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

    PubMed Central

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

    2013-01-01

    Radiofrequency (RF) field (B1) 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 B1 and MRI homogeneity by using pre-emphasized non-uniform B1 distribution. The intrinsic B1 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 B1 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 B1 distribution generated by the MTL volume coil, relatively uniform B1 distribution and homogeneous MR image (98% homogeneity) within the spherical phantom (15 cm diameter) were achieved with 4.5 mm thickness. The B1 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 B1 and MRI homogeneities within the phantom containing 125 mM saline. The overall results demonstrate an efficient B1 shimming approach for improving high field MRI. PMID:24040618

  18. 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. PMID:25895913

  19. 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. PMID:27403428

  20. Bayesian brain source imaging based on combined MEG/EEG and fMRI using MCMC

    PubMed Central

    Jun, Sung C.; George, John S.; Kim, Woohan; Paré-Blagoev, Juliana; Plis, Sergey; Ranken, Doug M.; Schmidt, David M.

    2010-01-01

    A number of brain imaging techniques have been developed in order to investigate brain function and to develop diagnostic tools for various brain disorders. Each modality has strengths as well as weaknesses compared to the others. Recent work has explored how multiple modalities can be integrated effectively so that they complement one another while maintaining their individual strengths. Bayesian inference employing Markov Chain Monte Carlo (MCMC) techniques provides a straightforward way to combine disparate forms of information while dealing with the uncertainty in each. In this paper we introduce methods of Bayesian inference as a way to integrate different forms of brain imaging data in a probabilistic framework. We formulate Bayesian integration of magnetoencephalography (MEG) data and functional magnetic resonance imaging (fMRI) data by incorporating fMRI data into a spatial prior. The usefulness and feasibility of the method are verified through testing with both simulated and empirical data. PMID:18314351

  1. 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

  2. Angiomia Imaging and Diagnostics, Angiography and Functional MRI

    MedlinePlus

    ... administer these procedures and interpret the results. As technology and understanding of disease pathology evolves, combinations of ... integrated and layered approach. In some cases, imaging technology, which has been around for a decade or ...

  3. Repeated BOLD-fMRI imaging of deep brain stimulation responses in rats.

    PubMed

    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

  4. 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

  5. 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

  6. Iterative image reconstruction that includes a total variation regularization for radial MRI.

    PubMed

    Kojima, Shinya; Shinohara, Hiroyuki; Hashimoto, Takeyuki; Hirata, Masami; Ueno, Eiko

    2015-07-01

    This paper presents an iterative image reconstruction method for radial encodings in MRI based on a total variation (TV) regularization. The algebraic reconstruction method combined with total variation regularization (ART_TV) is implemented with a regularization parameter specifying the weight of the TV term in the optimization process. We used numerical simulations of a Shepp-Logan phantom, as well as experimental imaging of a phantom that included a rectangular-wave chart, to evaluate the performance of ART_TV, and to compare it with that of the Fourier transform (FT) method. The trade-off between spatial resolution and signal-to-noise ratio (SNR) was investigated for different values of the regularization parameter by experiments on a phantom and a commercially available MRI system. ART_TV was inferior to the FT with respect to the evaluation of the modulation transfer function (MTF), especially at high frequencies; however, it outperformed the FT with regard to the SNR. In accordance with the results of SNR measurement, visual impression suggested that the image quality of ART_TV was better than that of the FT for reconstruction of a noisy image of a kiwi fruit. In conclusion, ART_TV provides radial MRI with improved image quality for low-SNR data; however, the regularization parameter in ART_TV is a critical factor for obtaining improvement over the FT. PMID:25990884

  7. Rapid dynamic radial MRI via reference image enforced histogram constrained reconstruction

    NASA Astrophysics Data System (ADS)

    Gaass, Thomas; Bauman, Grzegorz; Potdevin, Guillaume; Noël, Peter B.; Haase, Axel

    2014-03-01

    Exploiting spatio-temporal redundancies in sub-Nyquist sampled dynamic MRI for the suppression of undersampling artifacts was shown to be of great success. However, temporally averaged and blurred structures in image space composite data poses the risk of false information in the reconstruction. Within this work we assess the possibility of employing the composite image histogram as a measure of undersampling artifacts and as basis of their suppression. The proposed algorithm utilizes a histogram, computed from a composite image within a dynamically acquired interleaved radial MRI measurement as reference to compensate for the impact of undersampling in temporally resolved data without the incorporation of temporal averaging. In addition an image space regularization utilizing a single frame low-resolution reconstruction is implemented to enforce overall contrast fidelity. The performance of the approach was evaluated on a simulated radial dynamic MRI acquisition and on two functional in vivo radial cardiac acquisitions. Results demonstrate that the algorithm maintained contrast properties, details and temporal resolution in the images, while effectively suppressing undersampling artifacts.

  8. Rapid dynamic radial MRI via reference image enforced histogram constrained reconstruction.

    PubMed

    Gaass, Thomas; Bauman, Grzegorz; Potdevin, Guillaume; Noël, Peter B; Haase, Axel

    2014-03-01

    Exploiting spatio-temporal redundancies in sub-Nyquist sampled dynamic MRI for the suppression of undersampling artifacts was shown to be of great success. However, temporally averaged and blurred structures in image space composite data poses the risk of false information in the reconstruction. Within this work we assess the possibility of employing the composite image histogram as a measure of undersampling artifacts and as basis of their suppression. The proposed algorithm utilizes a histogram, computed from a composite image within a dynamically acquired interleaved radial MRI measurement as reference to compensate for the impact of undersampling in temporally resolved data without the incorporation of temporal averaging. In addition an image space regularization utilizing a single frame low-resolution reconstruction is implemented to enforce overall contrast fidelity. The performance of the approach was evaluated on a simulated radial dynamic MRI acquisition and on two functional in vivo radial cardiac acquisitions. Results demonstrate that the algorithm maintained contrast properties, details and temporal resolution in the images, while effectively suppressing undersampling artifacts. PMID:24486719

  9. 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

  10. MRI Superresolution Using Self-Similarity and Image Priors

    PubMed Central

    Manjón, José V.; Coupé, Pierrick; Buades, Antonio; Collins, D. Louis; Robles, Montserrat

    2010-01-01

    In Magnetic Resonance Imaging typical clinical settings, both low- and high-resolution images of different types are routinarily acquired. In some cases, the acquired low-resolution images have to be upsampled to match with other high-resolution images for posterior analysis or postprocessing such as registration or multimodal segmentation. However, classical interpolation techniques are not able to recover the high-frequency information lost during the acquisition process. In the present paper, a new superresolution method is proposed to reconstruct high-resolution images from the low-resolution ones using information from coplanar high resolution images acquired of the same subject. Furthermore, the reconstruction process is constrained to be physically plausible with the MR acquisition model that allows a meaningful interpretation of the results. Experiments on synthetic and real data are supplied to show the effectiveness of the proposed approach. A comparison with classical state-of-the-art interpolation techniques is presented to demonstrate the improved performance of the proposed methodology. PMID:21197094

  11. Peri-intraprocedural imaging: US, CT, and MRI.

    PubMed

    Crocetti, Laura; Della Pina, Clotilde; Cioni, Dania; Lencioni, Riccardo

    2011-12-01

    Imaging in liver interventional oncology plays a key role in the entire process starting from patient selection, leading to patient treatment and continuing with patient follow-up. Pre-procedural imaging evaluation is aimed to determine the indication for interventional therapies according to the size, number, and location of hepatic lesions, to the presence of major vascular invasion, nodal disease, and distant metastases, and to choose the most suitable approach according to tumor histology. Ideal qualities of a targeting technique include clear delineation of the tumor tissue and the surrounding anatomy, coupled with real-time imaging, multiplanar, and interactive capabilities. Moreover, the modality of image guidance should visualize therapy effects during the intervention to assess coverage of the targeted tissue and to prevent unintended thermal injury to critical structures in the surroundings of the target. Post-treatment imaging is then imperative to evaluate response to therapy by assessing for residual or recurrent disease, revising prognosis, and guiding future therapy. In this article, the role of imaging in patient selection and treatment planning will be discussed. Recently amended RECIST (mRECIST) for evaluation of tumor response in hepatocellular carcinoma and specific treatment-related findings after thermal ablation, trans-arterial chemoembolization, and radioembolization will be reviewed. PMID:21584636

  12. A multimodal (MRI/ultrasound) cardiac phantom for imaging experiments

    NASA Astrophysics Data System (ADS)

    Tavakoli, Vahid; Kendrick, Michael; Shakeri, Mostafa; Alshaher, Motaz; Stoddard, Marcus F.; Amini, Amir

    2013-03-01

    A dynamic cardiac phantom can play a significant role in the evaluation and development of ultrasound and cardiac magnetic resonance (MR) motion tracking and registration methods. A four chamber multimodal cardiac phantom has been designed and built to simulate normal and pathologic hearts with different degrees of "infarction" and "scar tissues". In this set up, cardiac valves have been designed and modeled as well. The four-chamber structure can simulate the asymmetric ventricular, atrial and valve motions. Poly Vinyl Alcohol (PVA) is used as the principal material since it can simulate the shape, elasticity, and MR and ultrasound properties of the heart. The cardiac shape is simulated using a four-chamber mold made of polymer clay. An additional pathologic heart phantom containing stiff inclusions has been manufactured in order to simulate an infracted heart. The stiff inclusions are of different shapes and different degrees of elasticity and are able to simulate abnormal cardiac segments. The cardiac elasticity is adjusted based on freeze-thaw cycles of the PVA cryogel for normal and scarred regions. Ultrasound and MRI markers were inserted in the cardiac phantom as landmarks for validations. To the best of our knowledge, this is the first multimodal phantom that models a dynamic four-chamber human heart including the cardiac valve.

  13. 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.

  14. Top-Level System Designs for Hybrid Low-Field MRI-CT with Potential of Pulmonary Imaging

    NASA Astrophysics Data System (ADS)

    Yelleswarapu, Venkata R.; Liu, Fenglin; Cong, Wenxiang; Wang, Ge

    2014-11-01

    We previously discussed "omni-tomography", but intrinsic conflicts between the magnetic fields of the MRI and the X-ray tube within the CT are inherent. We propose that by using low-field MRI with a negligible fringe field at the site of the CT source, it is possible to create a CT-MRI system with minimal interference. Low field MRI is particularly useful for lung imaging, where hyperpolarized gas can enhance the signal. Three major designs were considered and simulated, with modifications in coil design and axis allowing for further variation. The first uses Halbach arrays to minimize magnetic fields outside, the second uses solenoids pairs with active shielding, and the third uses a rotating compact MRI-CT. Each system is low field, which may allow the implementation of a standard rotating CT. Both structural and functional information can be acquired simultaneously for a true hybrid image with matching temporal and spatial image acquisition.

  15. 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.

  16. 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.

  17. 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

  18. Ontology-Based Annotation of Brain MRI Images

    PubMed Central

    Mechouche, Ammar; Golbreich, Christine; Morandi, Xavier; Gibaud, Bernard

    2008-01-01

    This paper describes a hybrid system for annotating anatomical structures in brain Magnetic Resonance Images. The system involves both numerical knowledge from an atlas and symbolic knowledge represented in a rule-extended ontology, written in standard web languages, and symbolic constraints. The system combines this knowledge with graphical data automatically extracted from the images. The annotations of the parts of sulci and of gyri located in a region of interest selected by the user are obtained with a reasoning based on a Constraint Satisfaction Problem solving combined with Description Logics inference services. The first results obtained with both normal and pathological data are promising. PMID:18998967

  19. Ultra-fast MRI of the human brain with simultaneous multi-slice imaging

    NASA Astrophysics Data System (ADS)

    Feinberg, David A.; Setsompop, Kawin

    2013-04-01

    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 improving the statistical definition of neuronal networks, and (ii) diffusion based fiber tractography to visualize structural connections in the human brain. Several applications and evaluations are underway which show promise for this family of fast imaging sequences.

  20. 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

  1. Measuring Thickness of Middle Ear Mucosa Using MRI and CT Imaging versus Histopathology

    PubMed Central

    Nyc, Mary Ann; Kim, Sang Gyoon; Kapoor, Anil; Jung, Timothy

    2012-01-01

    Objective. Otitis media (OM) is characterized by increased middle ear effusion and inflammation of middle ear tissue. In this study, we compared two radiographic methods of analyzing inflammation by measuring mucosal thickness (MT). Methods. 28 chinchillas were divided into three treatment groups consisting of a vehicle control group and two glucocorticoid groups. 6 underwent treatment by vehicle control, 10 were treated with ciprofloxacin 0.3%/dexamethasone 0.1% (DEX), and 10 received ciprofloxacin 0.2%/hydrocortisone 1% (HC). 96 hrs post-LPS inoculation, chinchillas were euthanized and their temporal bones were removed for analyses. Results. MRI scans (F = 146.0861, P-value <0.0001) and histology (χ2 = 40.5267, P-value <0.0001) revealed statistically significant differences in MT measurements among treatment groups, whereas CT imaging did not. DEX-treated chinchillas exhibited overall significantly smaller MT values. Conclusion. Imaging MT was effective for determining severity of inflammation due to OM. Previous gold standard methods using histopathology compromise tissue integrity by chemical manipulation and dehydration effects. MRI and CT scanning are viable tools to preserve tissue and examine changes in MT. In this study, MRI provided more information about internal, soft tissue structures. In a clinical setting, MRI could be used for diagnosing and tracking severe or chronic OM. PMID:22505940

  2. Measuring Thickness of Middle Ear Mucosa Using MRI and CT Imaging versus Histopathology.

    PubMed

    Nyc, Mary Ann; Kim, Sang Gyoon; Kapoor, Anil; Jung, Timothy

    2012-01-01

    Objective. Otitis media (OM) is characterized by increased middle ear effusion and inflammation of middle ear tissue. In this study, we compared two radiographic methods of analyzing inflammation by measuring mucosal thickness (MT). Methods. 28 chinchillas were divided into three treatment groups consisting of a vehicle control group and two glucocorticoid groups. 6 underwent treatment by vehicle control, 10 were treated with ciprofloxacin 0.3%/dexamethasone 0.1% (DEX), and 10 received ciprofloxacin 0.2%/hydrocortisone 1% (HC). 96 hrs post-LPS inoculation, chinchillas were euthanized and their temporal bones were removed for analyses. Results. MRI scans (F = 146.0861, P-value <0.0001) and histology (χ(2) = 40.5267, P-value <0.0001) revealed statistically significant differences in MT measurements among treatment groups, whereas CT imaging did not. DEX-treated chinchillas exhibited overall significantly smaller MT values. Conclusion. Imaging MT was effective for determining severity of inflammation due to OM. Previous gold standard methods using histopathology compromise tissue integrity by chemical manipulation and dehydration effects. MRI and CT scanning are viable tools to preserve tissue and examine changes in MT. In this study, MRI provided more information about internal, soft tissue structures. In a clinical setting, MRI could be used for diagnosing and tracking severe or chronic OM. PMID:22505940

  3. 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. PMID:21893391

  4. 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

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

    PubMed

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

    2015-01-15

    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 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/T2w 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

  6. 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

  7. 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.

  8. 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

  9. Comparison of Parallel MRI Reconstruction Methods for Accelerated 3D Fast Spin-Echo Imaging

    PubMed Central

    Xiao, Zhikui; Hoge, W. Scott; Mulkern, R.V.; Zhao, Lei; Hu, Guangshu; Kyriakos, Walid E.

    2014-01-01

    Parallel MRI (pMRI) achieves imaging acceleration by partially substituting gradient-encoding steps with spatial information contained in the component coils of the acquisition array. Variable-density subsampling in pMRI was previously shown to yield improved two-dimensional (2D) imaging in comparison to uniform subsampling, but has yet to be used routinely in clinical practice. In an effort to reduce acquisition time for 3D fast spin-echo (3D-FSE) sequences, this work explores a specific nonuniform sampling scheme for 3D imaging, subsampling along two phase-encoding (PE) directions on a rectilinear grid. We use two reconstruction methods—2D-GRAPPA-Operator and 2D-SPACE RIP—and present a comparison between them. We show that high-quality images can be reconstructed using both techniques. To evaluate the proposed sampling method and reconstruction schemes, results via simulation, phantom study, and in vivo 3D human data are shown. We find that fewer artifacts can be seen in the 2D-SPACE RIP reconstructions than in 2D-GRAPPA-Operator reconstructions, with comparable reconstruction times. PMID:18727083

  10. Efficiency of Non-Contrast-Enhanced Liver Imaging Sequences Added to Initial Rectal MRI in Rectal Cancer Patients

    PubMed Central

    Kwon, Gene-hyuk; Kim, Kyung Ah; Hwang, Seong Su; Park, Soo Youn; Kim, Hyun A.; Choi, Sun Young; Kim, Ji Woong

    2015-01-01

    Purpose The purpose of this study was to estimate the value of addition of liver imaging to initial rectal magnetic resonance imaging (MRI) for detection of liver metastasis and evaluate imaging predictors of a high risk of liver metastasis on rectal MRI. Methods We enrolled 144 patients who from October 2010 to May 2013 underwent rectal MRI with T2-weighted imaging (T2WI) and diffusion-weighted imaging (DWI) (b values = 50, 500, and 900 s/mm2) of the liver and abdominopelvic computed tomography (APCT) for the initial staging of rectal cancer. Two reviewers scored the possibility of liver metastasis on different sets of liver images (T2WI, DWI, and combined T2WI and DWI) and APCT and reached a conclusion by consensus for different analytic results. Imaging features from rectal MRI were also analyzed. The diagnostic performances of CT and an additional liver scan to detect liver metastasis were compared. Multivariate logistic regression to determine independent predictors of liver metastasis among rectal MRI features and tumor markers was performed. This retrospective study was approved by the Institutional Review Board, and the requirement for informed consent was waived. Results All sets of liver images were more effective than APCT for detecting liver metastasis, and DWI was the most effective. Perivascular stranding and anal sphincter invasion were statistically significant for liver metastasis (p = 0.0077 and p = 0.0471), while extramural vascular invasion based on MRI (mrEMVI) was marginally significant (p = 0.0534). Conclusion The addition of non-contrast-enhanced liver imaging, particularly DWI, to initial rectal MRI in rectal cancer patients could facilitate detection of liver metastasis without APCT. Perivascular stranding, anal sphincter invasion, and mrEMVI detected on rectal MRI were important imaging predictors of liver metastasis. PMID:26348217

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

    SciTech Connect

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

    2008-12-15

    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 ({approx}0.7 mm) in the best case and 2.8 pixels ({approx}1.4 mm) in the worst case for the five patients studied.

  12. Brain MRI Tumor Detection using Active Contour Model and Local Image Fitting Energy

    NASA Astrophysics Data System (ADS)

    Nabizadeh, Nooshin; John, Nigel

    2014-03-01

    Automatic abnormality detection in Magnetic Resonance Imaging (MRI) is an important issue in many diagnostic and therapeutic applications. Here an automatic brain tumor detection method is introduced that uses T1-weighted images and K. Zhang et. al.'s active contour model driven by local image fitting (LIF) energy. Local image fitting energy obtains the local image information, which enables the algorithm to segment images with intensity inhomogeneities. Advantage of this method is that the LIF energy functional has less computational complexity than the local binary fitting (LBF) energy functional; moreover, it maintains the sub-pixel accuracy and boundary regularization properties. In Zhang's algorithm, a new level set method based on Gaussian filtering is used to implement the variational formulation, which is not only vigorous to prevent the energy functional from being trapped into local minimum, but also effective in keeping the level set function regular. Experiments show that the proposed method achieves high accuracy brain tumor segmentation results.

  13. Model for B1 Imaging in MRI Using the Rotating RF Field

    PubMed Central

    Weber, Ewald; Crozier, Stuart

    2014-01-01

    Conventionally, magnetic resonance imaging (MRI) is performed by pulsing gradient coils, which invariably leads to strong acoustic noise, patient safety concerns due to induced currents, and costly power/space requirements. This modeling study investigates a new silent, gradient coil-free MR imaging method, in which a radiofrequency (RF) coil and its nonuniform field (B 1 +) are mechanically rotated about the patient. The advantage of the rotating B 1 + field is that, for the first time, it provides a large number of degrees of freedom to aid a successful B 1 + image encoding process. The mathematical modeling was performed using flip angle modulation as part of a finite-difference-based Bloch equation solver. Preliminary results suggest that representative MR images with intensity deviations of <5% from the original image can be obtained using rotating RF field approach. This method may open up new avenues towards anatomical and functional imaging in medicine. PMID:24963336

  14. 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

  15. Assessment of bias for MRI diffusion tensor imaging using SIMEX.

    PubMed

    Lauzon, Carolyn B; Asman, Andrew J; Crainiceanu, Ciprian; Caffo, Brian C; Landman, Bennett A

    2011-01-01

    Diffusion Tensor Imaging (DTI) is a Magnetic Resonance Imaging method for measuring water diffusion in vivo. One powerful DTI contrast is fractional anisotropy (FA). FA reflects the strength of water's diffusion directional preference and is a primary metric for neuronal fiber tracking. As with other DTI contrasts, FA measurements are obscured by the well established presence of bias. DTI bias has been challenging to assess because it is a multivariable problem including SNR, six tensor parameters, and the DTI collection and processing method used. SIMEX is a modem statistical technique that estimates bias by tracking measurement error as a function of added noise. Here, we use SIMEX to assess bias in FA measurements and show the method provides; i) accurate FA bias estimates, ii) representation of FA bias that is data set specific and accessible to non-statisticians, and iii) a first time possibility for incorporation of bias into DTI data analysis. PMID:21995019

  16. Imaging knee position using MRI, RSA/CT and 3D digitisation.

    PubMed

    McPherson, A; Kärrholm, J; Pinskerova, V; Sosna, A; Martelli, S

    2005-02-01

    The purpose of this study was to compare 3 methods of imaging knee position. Three fresh cadaver knees were imaged at 6 flexion angles between 0 degrees and 120 degrees by MRI, a combination of RSA and CT and 3D digitisation (in two knees). Virtual models of all 42 positions were created using suitable computer software. Each virtual model was aligned to a newly defined anatomically based Cartesian coordinate system. The angular rotations around the 3 coordinate system axes were calculated directly from the aligned virtual models using rigid body kinematics and found to be equally accurate for the 3 methods. The 3 rotations in each knee could be depicted using anatomy-based diagrams for all 3 methods. We conclude that the 3 methods of data acquisition are equally and adequately accurate in vitro. MRI may be the most useful in vivo. PMID:15598452

  17. Molecular imaging of atherosclerosis with nanoparticle-based fluorinated MRI contrast agents

    PubMed Central

    Palekar, Rohun U; Jallouk, Andrew P; Lanza, Gregory M; Pan, Hua; Wickline, Samuel A

    2015-01-01

    As atherosclerosis remains one of the most prevalent causes of patient mortality, the ability to diagnose early signs of plaque rupture and thrombosis represents a significant clinical need. With recent advances in nanotechnology, it is now possible to image specific molecular processes noninvasively with MRI, using various types of nanoparticles as contrast agents. In the context of cardiovascular disease, it is possible to specifically deliver contrast agents to an epitope of interest for detecting vascular inflammatory processes, which serve as predecessors to atherosclerotic plaque development. Herein, we review various applications of nanotechnology in detecting atherosclerosis using MRI, with an emphasis on perfluorocarbon nanoparticles and fluorine imaging, along with theranostic prospects of nanotechnology in cardiovascular disease. PMID:26080701

  18. 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. PMID:26736354

  19. 3D segmentation of masses in DCE-MRI images using FCM and adaptive MRF

    NASA Astrophysics Data System (ADS)

    Zhang, Chengjie; Li, Lihua

    2014-03-01

    Dynamic contrast enhanced magnetic resonance imaging (DCE-MRI) is a sensitive imaging modality for the detection of breast cancer. Automated segmentation of breast lesions in DCE-MRI images is challenging due to inherent signal-to-noise ratios and high inter-patient variability. A novel 3D segmentation method based on FCM and MRF is proposed in this study. In this method, a MRI image is segmented by spatial FCM, firstly. And then MRF segmentation is conducted to refine the result. We combined with the 3D information of lesion in the MRF segmentation process by using segmentation result of contiguous slices to constraint the slice segmentation. At the same time, a membership matrix of FCM segmentation result is used for adaptive adjustment of Markov parameters in MRF segmentation process. The proposed method was applied for lesion segmentation on 145 breast DCE-MRI examinations (86 malignant and 59 benign cases). An evaluation of segmentation was taken using the traditional overlap rate method between the segmented region and hand-drawing ground truth. The average overlap rates for benign and malignant lesions are 0.764 and 0.755 respectively. Then we extracted five features based on the segmentation region, and used an artificial neural network (ANN) to classify between malignant and benign cases. The ANN had a classification performance measured by the area under the ROC curve of AUC=0.73. The positive and negative predictive values were 0.86 and 0.58, respectively. The results demonstrate the proposed method not only achieves a better segmentation performance in accuracy also has a reasonable classification performance.

  20. Magnetic resonance imaging (MRI) study of jet height hysteresis in packed beds

    NASA Astrophysics Data System (ADS)

    Köhl, Maximilian H.; Lu, Guang; Third, James R.; Prüssmann, Klaas P.; Müller, Christoph R.

    2013-06-01

    The jet-spout transition in fluidized beds can show hysteretic behavior. In this study the jet-spout transition was studied as a function of orifice velocity for particles of different size and shape using Magnetic Resonance Imaging (MRI). The measurements showed that the particle shape primarily affect to the width of the hysteresis loop whereas particle size governs the position of the hysteresis loop with regards to the orifice velocity.

  1. Primary hydatid cyst of the gallbladder: an unusual localization diagnosed by Magnetic Resonance Imaging (MRI)

    PubMed Central

    Noomene, Rabii; Maamer, Anis Ben; Bouhafa, Ahmed; Haoues, Noomen; Oueslati, Abdelaziz; Cherif, Abderraouf

    2013-01-01

    Hydatid disease is endemic in Tunisia and has been considered as one of the most common surgical pathology. Several localizations have been described, but hydatidosis of the liver is the most frequent clinical entity. Primary hydatid cyst of the gallbladder is very rare. We report in this observation a new case of primary hydatid cyst of the gallbladder diagnosed by Magnetic Resonance Imaging (MRI). PMID:23504393

  2. Robust segmentation of 4D cardiac MRI-tagged images via spatio-temporal propagation

    NASA Astrophysics Data System (ADS)

    Qian, Zhen; Huang, Xiaolei; Metaxas, Dimitris N.; Axel, Leon

    2005-04-01

    In this paper we present a robust method for segmenting and tracking cardiac contours and tags in 4D cardiac MRI tagged images via spatio-temporal propagation. Our method is based on two main techniques: the Metamorphs Segmentation for robust boundary estimation, and the tunable Gabor filter bank for tagging lines enhancement, removal and myocardium tracking. We have developed a prototype system based on the integration of these two techniques, and achieved efficient, robust segmentation and tracking with minimal human interaction.

  3. Recent advances in MRI technology: Implications for image quality and patient safety

    PubMed Central

    Sobol, Wlad T.

    2012-01-01

    Recent advances in MRI technology are presented, with emphasis on how this new technology impacts clinical operations (better image quality, faster exam times, and improved throughput). In addition, implications for patient safety are discussed with emphasis on the risk of patient injury due to either high local specific absorption rate (SAR) or large cumulative energy doses delivered during long exam times. Patient comfort issues are examined as well. PMID:23961024

  4. 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.

  5. Pitfalls in whole body MRI with diffusion weighted imaging performed on patients with lymphoma: What radiologists should know.

    PubMed

    Albano, Domenico; La Grutta, Ludovico; Grassedonio, Emanuele; Patti, Caterina; Lagalla, Roberto; Midiri, Massimo; Galia, Massimo

    2016-09-01

    The technological advances in radiological imaging and the relevance of a diagnostic tool that may reduce radiation-induced long-term effects have led to a widespread use of whole body magnetic resonance imaging (WB-MRI) with diffusion weighted imaging for oncologic patients. A lot of studies demonstrated the feasibility and reliability of WB-MRI as an alternative technique for lymphoma staging and response assessment during and after treatment. In this paper, taking advantage of our 2years of experience using WB-MRI for lymphoma, we discuss the main pitfalls and artifacts radiologists should know examining a WB-MRI performed on this typology of patients in order to avoid images misinterpretation. PMID:27114337

  6. 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

  7. Non-cryogenic anatomical imaging in ultra-low field regime: Hand MRI demonstration

    PubMed Central

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

    2011-01-01

    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, less stringent requirements for uniform fields etc., remaining. In this paper we demonstrate use of this system to image a human hand with up to 1.5 mm resolution. The signal-to-noise ratio was sufficient to reveal anatomical features within a scan time of less than 7 minutes. This prototype can be scaled up for constructing head and full body scanners, and work is in progress toward demonstration of head imaging. PMID:21700482

  8. Non-cryogenic anatomical imaging in ultra-low field regime: Hand MRI demonstration

    NASA Astrophysics Data System (ADS)

    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 1.5 mm 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.

  9. 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.

  10. 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

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

    PubMed

    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

  12. 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

    2016-09-01

    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

  13. 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

  14. Image analysis methods for tagged MRI cardiac studies

    NASA Astrophysics Data System (ADS)

    Guttman, Michael A.; Prince, Jerry L.

    1990-07-01

    Tracking of magnetic resonance (MR) tags in myocardial tissue promises to be an effective tool in the assessment of myocardial motion. The amount of data acquired is very large and the measurements are numerous and must be precise requiring automated tracking methods. We describe a hierarchy of image processing steps that estimate both the endocardial and epicardial boundaries of the left ventricle and also estimate the spines of radial tags that emanate outward from the left ventricular cavity. The first stage determines the position of the myocardial boundaries for each of 128 rays emanating from the origin. To counter the deleterious effects of noise and the presence of the tags when determining the boundary positions we use nonlinear filtering concepts from mathematical morphology together with a prion knowledge related to boundary smoothness to improve the estimates. The second stage estimates the tag spines by matching a template in a direction orthogonal to the expected tag direction. We show results on tagged images and discuss further research directions. 1.

  15. Magnetic Resonance Imaging (MRI) of PEM Dehydration and Gas Manifold Flooding During Continuous Fuel Cell Operation

    SciTech Connect

    Minard, Kevin R.; Vishwanathan, Vilanyur V.; Majors, Paul D.; Wang, Li Q.; Rieke, Peter C.

    2006-10-27

    The methods, apparatus, and results are reported for in-situ, near real time, magnetic resonance imaging (MRI) of MEA dehydration and gas manifold flooding in an operating PEM fuel cell. To acquire high-resolution, artifact-free images for visualizing water distribution, acquisition parameters for a standard, two-dimensional (2D), spin-echo sequence were first optimized for the measured magnetic field heterogeneity induced by fuel cell components. 2D images of water inside the fuel cell were then acquired every 128 seconds during 11.4 hours of continuous operation under constant load. Collected images revealed that MEA dehydration proceeded non-uniformly across its plane, starting from gas inlets and ending at gas outlets, and that upon completion of this dehydration process manifold flooding began. To understand these observations, acquired images were correlated to the current output and operating characteristics of the fuel cell. Results demonstrate the power of MRI for in-situ, near real-time imaging of water distribution and non-uniformity in operating PEM fuel cells, and highlight its utility for understanding PEM fuel cell operation, the causes of cell failure, and for developing new strategies of water management.

  16. Methods on Skull Stripping of MRI Head Scan Images-a Review.

    PubMed

    Kalavathi, P; Prasath, V B Surya

    2016-06-01

    The high resolution magnetic resonance (MR) brain images contain some non-brain tissues such as skin, fat, muscle, neck, and eye balls compared to the functional images namely positron emission tomography (PET), single photon emission computed tomography (SPECT), and functional magnetic resonance imaging (fMRI) which usually contain relatively less non-brain tissues. The presence of these non-brain tissues is considered as a major obstacle for automatic brain image segmentation and analysis techniques. Therefore, quantitative morphometric studies of MR brain images often require a preliminary processing to isolate the brain from extra-cranial or non-brain tissues, commonly referred to as skull stripping. This paper describes the available methods on skull stripping and an exploratory review of recent literature on the existing skull stripping methods. PMID:26628083

  17. Accelerating image registration of MRI by GPU-based parallel computation.

    PubMed

    Huang, Teng-Yi; Tang, Yu-Wei; Ju, Shiun-Ying

    2011-06-01

    Automatic image registration for MRI applications generally requires many iteration loops and is, therefore, a time-consuming task. This drawback prolongs data analysis and delays the workflow of clinical routines. Recent advances in the massively parallel computation of graphic processing units (GPUs) may be a solution to this problem. This study proposes a method to accelerate registration calculations, especially for the popular statistical parametric mapping (SPM) system. This study reimplemented the image registration of SPM system to achieve an approximately 14-fold increase in speed in registering single-modality intrasubject data sets. The proposed program is fully compatible with SPM, allowing the user to simply replace the original image registration library of SPM to gain the benefit of the computation power provided by commodity graphic processors. In conclusion, the GPU computation method is a practical way to accelerate automatic image registration. This technology promises a broader scope of application in the field of image registration. PMID:21531103

  18. Magnetic Resonance Imaging (MRI) Evaluation of Developmental Delay in Pediatric Patients

    PubMed Central

    Syed, Naziya P.; Murthy, G.S.N.; Nori, Madhavi; Abkari, Anand; Pooja, B.K.; Venkateswarlu, J.

    2015-01-01

    Introduction: Developmental delay is defined as significant delay in one or more developmental domains. Magnetic Resonance Imaging (MRI) is the best modality to investigate such patients. Evaluation of a child with developmental delay is important not only because it allows early diagnosis and treatment but also helpful for parental counseling regarding the outcome of their child and to identify any possible risk of recurrence in the siblings. Thus this study was undertaken to evaluate the developmental delay in Indian children which will help the clinicians in providing an estimation of the child’s ultimate developmental potential and organize specific treatment requirement and also relieve parental apprehension. Aims and Objectives: To study the prevalence of normal and abnormal MRI in pediatric patients presenting with developmental delay and further categorize the abnormal MRI based on its morphological features. Materials and Methods: It is a prospective, observational & descriptive study of MRI Brain in 81 paediatric patients (46 Males and 35 Females), aged between three months to 12 years; presenting with developmental delay in Deccan College of Medical Sciences, Hyderabad; over a period of three years (Sept 2011 to Sept 2014). MRI brain was done on 1.5T Siemens Magnetom Essenza & 0.35T Magnetom C with appropriate sequences and planes after making the child sleep/sedated/ anesthetized. Various anatomical structures like Ventricles, Corpus callosum, etc were systematically assessed. The MRI findings were divided into various aetiological subgroups. Results: Normal MRI findings were seen in 32% cases and 68% had abnormal findings of which the proportion of Traumatic/ Neurovascular Diseases, Congenital & Developmental, Metabolic and Degenerative, neoplastic and non specific were 31%, 17%, 10%, 2.5% and 7.5% respectively. The ventricles and white matter mainly the corpus callosum were the most commonly affected anatomical structures. The diagnostic yield was

  19. 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.

  20. 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

  1. 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. PMID:26034414

  2. 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.

  3. 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

  4. Multiple template-based fluoroscopic tracking of lung tumor mass without implanted fiducial markers

    NASA Astrophysics Data System (ADS)

    Cui, Ying; Dy, Jennifer G.; Sharp, Gregory C.; Alexander, Brian; Jiang, Steve B.

    2007-10-01

    Precise lung tumor localization in real time is particularly important for some motion management techniques, such as respiratory gating or beam tracking with a dynamic multi-leaf collimator, due to the reduced clinical tumor volume (CTV) to planning target volume (PTV) margin and/or the escalated dose. There might be large uncertainties in deriving tumor position from external respiratory surrogates. While tracking implanted fiducial markers has sufficient accuracy, this procedure may not be widely accepted due to the risk of pneumothorax. Previously, we have developed a technique to generate gating signals from fluoroscopic images without implanted fiducial markers using a template matching method (Berbeco et al 2005 Phys. Med. Biol. 50 4481-90, Cui et al 2007 Phys. Med. Biol. 52 741-55). In this paper, we present an extension of this method to multiple-template matching for directly tracking the lung tumor mass in fluoroscopy video. The basic idea is as follows: (i) during the patient setup session, a pair of orthogonal fluoroscopic image sequences are taken and processed off-line to generate a set of reference templates that correspond to different breathing phases and tumor positions; (ii) during treatment delivery, fluoroscopic images are continuously acquired and processed; (iii) the similarity between each reference template and the processed incoming image is calculated; (iv) the tumor position in the incoming image is then estimated by combining the tumor centroid coordinates in reference templates with proper weights based on the measured similarities. With different handling of image processing and similarity calculation, two such multiple-template tracking techniques have been developed: one based on motion-enhanced templates and Pearson's correlation score while the other based on eigen templates and mean-squared error. The developed techniques have been tested on six sequences of fluoroscopic images from six lung cancer patients against the reference

  5. Progress in the Development of a new Angiography Suite including the High Resolution Micro-Angiographic Fluoroscope (MAF), a Control, Acquisition, Processing, and Image Display System (CAPIDS), and a New Detector Changer Integrated into a Commercial C-Arm Angiography Unit to Enable Clinical Use.

    PubMed

    Wang, Weiyuan; Ionita, Ciprian N; Keleshis, Christos; Kuhls-Gilcrist, Andrew; Jain, Amit; Bednarek, Daniel; Rudin, Stephen

    2010-03-23

    Due to the high-resolution needs of angiographic and interventional vascular imaging, a Micro-Angiographic Fluoroscope (MAF) detector with a Control, Acquisition, Processing, and Image Display System (CAPIDS) was installed on a detector changer which was attached to the C-arm of a clinical angiographic unit. The MAF detector provides high-resolution, high-sensitivity, and real-time imaging capabilities and consists of a 300 μm-thick CsI phosphor, a dual stage micro-channel plate light image intensifier (LII) coupled to a fiber optic taper (FOT), and a scientific grade frame-transfer CCD camera, providing an image matrix of 1024×1024 35 μm square pixels with 12 bit depth. The Solid-State X-Ray Image Intensifier (SSXII) is an EMCCD (Electron Multiplying charge-coupled device) based detector which provides an image matrix of 1k×1k 32 μm square pixels with 12 bit depth. The changer allows the MAF or a SSXII region-of-interest (ROI) detector to be inserted in front of the standard flat-panel detector (FPD) when higher resolution is needed during angiographic or interventional vascular imaging procedures. The CAPIDS was developed and implemented using LabVIEW software and provides a user-friendly interface that enables control of several clinical radiographic imaging modes of the MAF or SSXII including: fluoroscopy, roadmapping, radiography, and digital-subtraction-angiography (DSA). The total system has been used for image guidance during endovascular image-guided interventions (EIGI) using prototype self-expanding asymmetric vascular stents (SAVS) in over 10 rabbit aneurysm creation and treatment experiments which have demonstrated the system's potential benefits for future clinical use. PMID:21243037

  6. Progress in the development of a new angiography suite including the high resolution micro-angiographic fluoroscope (MAF): a control, acquisition, processing, and image display system (CAPIDS), and a new detector changer integrated into a commercial C-arm angiography unit to enable clinical use

    NASA Astrophysics Data System (ADS)

    Wang, Weiyuan; Ionita, Ciprian N.; Keleshis, Christos; Kuhls-Gilcrist, Andrew; Jain, Amit; Bednarek, Daniel; Rudin, Stephen

    2010-04-01

    Due to the high-resolution needs of angiographic and interventional vascular imaging, a Micro-Angiographic Fluoroscope (MAF) detector with a Control, Acquisition, Processing, and Image Display System (CAPIDS) was installed on a detector changer which was attached to the C-arm of a clinical angiographic unit. The MAF detector provides high-resolution, high-sensitivity, and real-time imaging capabilities and consists of a 300 μm-thick CsI phosphor, a dual stage micro-channel plate light image intensifier (LII) coupled to a fiber optic taper (FOT), and a scientific grade frame-transfer CCD camera, providing an image matrix of 1024×1024 35 μm square pixels with 12 bit depth. The Solid-State X-Ray Image Intensifier (SSXII) is an EMCCD (Electron Multiplying charge-coupled device) based detector which provides an image matrix of 1k×1k 32 μm square pixels with 12 bit depth. The changer allows the MAF or a SSXII region-of-interest (ROI) detector to be inserted in front of the standard flat-panel detector (FPD) when higher resolution is needed during angiographic or interventional vascular imaging procedures. The CAPIDS was developed and implemented using LabVIEW software and provides a user-friendly interface that enables control of several clinical radiographic imaging modes of the MAF or SSXII including: fluoroscopy, roadmapping, radiography, and digital-subtraction-angiography (DSA). The total system has been used for image guidance during endovascular image-guided interventions (EIGI) using prototype self-expanding asymmetric vascular stents (SAVS) in over 10 rabbit aneurysm creation and treatment experiments which have demonstrated the system's potential benefits for future clinical use.

  7. Progress in the Development of a new Angiography Suite including the High Resolution Micro-Angiographic Fluoroscope (MAF), a Control, Acquisition, Processing, and Image Display System (CAPIDS), and a New Detector Changer Integrated into a Commercial C-Arm Angiography Unit to Enable Clinical Use

    PubMed Central

    Wang, Weiyuan; Ionita, Ciprian N; Keleshis, Christos; Kuhls-Gilcrist, Andrew; Jain, Amit; Bednarek, Daniel; Rudin, Stephen

    2010-01-01

    Due to the high-resolution needs of angiographic and interventional vascular imaging, a Micro-Angiographic Fluoroscope (MAF) detector with a Control, Acquisition, Processing, and Image Display System (CAPIDS) was installed on a detector changer which was attached to the C-arm of a clinical angiographic unit. The MAF detector provides high-resolution, high-sensitivity, and real-time imaging capabilities and consists of a 300 μm-thick CsI phosphor, a dual stage micro-channel plate light image intensifier (LII) coupled to a fiber optic taper (FOT), and a scientific grade frame-transfer CCD camera, providing an image matrix of 1024×1024 35 μm square pixels with 12 bit depth. The Solid-State X-Ray Image Intensifier (SSXII) is an EMCCD (Electron Multiplying charge-coupled device) based detector which provides an image matrix of 1k×1k 32 μm square pixels with 12 bit depth. The changer allows the MAF or a SSXII region-of-interest (ROI) detector to be inserted in front of the standard flat-panel detector (FPD) when higher resolution is needed during angiographic or interventional vascular imaging procedures. The CAPIDS was developed and implemented using LabVIEW software and provides a user-friendly interface that enables control of several clinical radiographic imaging modes of the MAF or SSXII including: fluoroscopy, roadmapping, radiography, and digital-subtraction-angiography (DSA). The total system has been used for image guidance during endovascular image-guided interventions (EIGI) using prototype self-expanding asymmetric vascular stents (SAVS) in over 10 rabbit aneurysm creation and treatment experiments which have demonstrated the system's potential benefits for future clinical use. PMID:21243037

  8. 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.

  9. Denoising of brain MRI images using modified PDE based on pixel similarity

    NASA Astrophysics Data System (ADS)

    Jin, Renchao; Song, Enmin; Zhang, Lijuan; Min, Zhifang; Xu, Xiangyang; Huang, Chih-Cheng

    2008-03-01

    Although various image denoising methods such as PDE-based algorithms have made remarkable progress in the past years, the trade-off between noise reduction and edge preservation is still an interesting and difficult problem in the field of image processing and analysis. A new image denoising algorithm, using a modified PDE model based on pixel similarity, is proposed to deal with the problem. The pixel similarity measures the similarity between two pixels. Then the neighboring consistency of the center pixel can be calculated. Informally, if a pixel is not consistent enough with its surrounding pixels, it can be considered as a noise, but an extremely strong inconsistency suggests an edge. The pixel similarity is a probability measure, its value is between 0 and 1. According to the neighboring consistency of the pixel, a diffusion control factor can be determined by a simple thresholding rule. The factor is combined into the primary partial differential equation as an adjusting factor for controlling the speed of diffusion for different type of pixels. An evaluation of the proposed algorithm on the simulated brain MRI images was carried out. The initial experimental results showed that the new algorithm can smooth the MRI images better while keeping the edges better and achieve higher peak signal to noise ratio (PSNR) comparing with several existing denoising algorithms.

  10. 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).

  11. Evaluation of aortic regurgitation by using PC MRI: A comparison of the accuracies at different image plane locations

    NASA Astrophysics Data System (ADS)

    Kim, Byeong-Gull; Kim, Kyung-Soo; Kim, Soon-Bae; Chung, Woon-Kwan; Cho, Jae-Hwan; Park, Yong-Soon

    2012-12-01

    The goal of this study is to determine which imaging location on phase contrast magnetic resonance imaging (PC MRI) best correlates with echocardiography to enable the severity of aortic regurgitation to be accurately evaluated by using PC MRI. The subjects were 34 patients with aortic regurgitation confirmed by echocardiography and cardiac MRI. Two velocity distribution images were obtained by positioning image planes above and below the aortic valve in the PC MRI. Using the acquired images, regurgitation fractions were calculated by calculating the average forward and reverse blood flows. The severity of aortic regurgitation was then evaluated and compared with the severity as determined by using echocardiography. When image planes were positioned above the aortic valve, the regurgitation fraction obtained by using PC MRI was 44.5 ± 18.7%, and when planes were positioned below the valve, the regurgitation fraction was 34.8 ± 15.9%. Regarding agreement with echocardiographic findings, concurrence was shown to be 50% when image planes sections were positioned above the valve and 85.3% when they were positioned below the valve. The present study shows that if image planes are positioned below the valve rather than above the valve, provides as accurate evaluation of the severity of aortic regurgitation.

  12. A machine learning approach for deformable guide-wire tracking in fluoroscopic sequences.

    PubMed

    Pauly, Olivier; Heibel, Hauke; Navab, Nassir

    2010-01-01

    Deformable guide-wire tracking in fluoroscopic sequences is a challenging task due to the low signal to noise ratio of the images and the apparent complex motion of the object of interest. Common tracking methods are based on data terms that do not differentiate well between medical tools and anatomic background such as ribs and vertebrae. A data term learned directly from fluoroscopic sequences would be more adapted to the image characteristics and could help to improve tracking. In this work, our contribution is to learn the relationship between features extracted from the original image and the tracking error. By randomly deforming a guide-wire model around its ground truth position in one single reference frame, we explore the space spanned by these features. Therefore, a guide-wire motion distribution model is learned to reduce the intrisic dimensionality of this feature space. Random deformations and the corresponding features can be then automatically generated. In a regression approach, the function mapping this space to the tracking error is learned. The resulting data term is integrated into a tracking framework based on a second-order MAP-MRF formulation which is optimized by QPBO moves yielding high-quality tracking results. Experiments conducted on two fluoroscopic sequences show that our approach is a promising alternative for deformable tracking of guide-wires. PMID:20879418

  13. Adaptive 4D MR Imaging Using Navigator-Based Respiratory Signal for MRI-Guided Therapy

    PubMed Central

    Tokuda, Junichi; Morikawa, Shigehiro; Haque, Hasnine A.; Tsukamoto, Tetsuji; Matsumiya, Kiyoshi; Liao, Hongen; Masamune, Ken; Dohi, Takeyoshi

    2010-01-01

    For real-time 3D visualization of respiratory organ motion for MRI-guided therapy, a new adaptive 4D MR imaging method based on navigator echo and multiple gating windows was developed. This method was designed to acquire a time series of volumetric 3D images of a cyclically moving organ, enabling therapy to be guided by synchronizing the 4D image with the actual organ motion in real time. The proposed method was implemented in an open-configuration 0.5T clinical MR scanner. To evaluate the feasibility and determine optimal imaging conditions, studies were conducted with a phantom, volunteers, and a patient. In the phantom study the root mean square (RMS) position error in the 4D image of the cyclically moving phantom was 1.9 mm and the imaging time was ≈10 min when the 4D image had six frames. In the patient study, 4D images were successfully acquired under clinical conditions and a liver tumor was discriminated in the series of frames. The image quality was affected by the relations among the encoding direction, the slice orientation, and the direction of motion of the target organ. In conclusion, this study has shown that the proposed method is feasible and capable of providing a real-time dynamic 3D atlas for surgical navigation with sufficient accuracy and image quality. PMID:18429011

  14. 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.

  15. Microfluidic laminate-based phantom for diffusion tensor-magnetic resonance imaging (DT-MRI)

    PubMed Central

    Samuel, R; Sant, H J; Jiao, F; Johnson, C R; Gale, B K

    2011-01-01

    This paper reports fabrication of a magnetic resonance imaging (MRI) phantom created by stacking of multiple thin polydimethylsiloxane (PDMS) layers. PDMS is spin coated on SU-8 molds to obtain the desired layer thickness and imprints of the microchannel patterns that define the phantom geometry. This paper also identifies the unique challenges related to the fabrication and assembly of multiple thin layers and reports for the first time assembly of a large number of thin laminates of this nature. Use of photolithography techniques allows us to create a wide range of phantom geometries. The target dimensions of the phantoms reported here are (i) a stack of 30 thin PDMS layers of 10 µm thickness (ii) curved 5 µm × 5 µm microchannels with 8.7 µm spacing, and (iii) straight 5 µm × 5 µm microchannels with 3.6 µm spacing. SEM scans of the assembled phantoms show open microchannels and a monolithic cross-section with no visible interface between PDMS layers. Based on the results of diffusion tensor magnetic resonance imaging (DT-MRI) scan, the anisotropic diffusion of water molecules due to the physical restriction of the microchannels was detected, which means that the phantom can be used to calibrate and optimize MRI instrumentation. PMID:22865956

  16. Microfluidic laminate-based phantom for diffusion tensor-magnetic resonance imaging (DT-MRI).

    PubMed

    Samuel, R; Sant, H J; Jiao, F; Johnson, C R; Gale, B K

    2011-09-01

    This paper reports fabrication of a magnetic resonance imaging (MRI) phantom created by stacking of multiple thin polydimethylsiloxane (PDMS) layers. PDMS is spin coated on SU-8 molds to obtain the desired layer thickness and imprints of the microchannel patterns that define the phantom geometry. This paper also identifies the unique challenges related to the fabrication and assembly of multiple thin layers and reports for the first time assembly of a large number of thin laminates of this nature. Use of photolithography techniques allows us to create a wide range of phantom geometries. The target dimensions of the phantoms reported here are (i) a stack of 30 thin PDMS layers of 10 µm thickness (ii) curved 5 µm × 5 µm microchannels with 8.7 µm spacing, and (iii) straight 5 µm × 5 µm microchannels with 3.6 µm spacing. SEM scans of the assembled phantoms show open microchannels and a monolithic cross-section with no visible interface between PDMS layers. Based on the results of diffusion tensor magnetic resonance imaging (DT-MRI) scan, the anisotropic diffusion of water molecules due to the physical restriction of the microchannels was detected, which means that the phantom can be used to calibrate and optimize MRI instrumentation. PMID:22865956

  17. 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.

  18. 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

  19. 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

  20. Diagnostic imaging in 13 cases of Rasmussen's encephalitis: can early MRI suggest the diagnosis?

    PubMed

    Chiapparini, L; Granata, T; Farina, L; Ciceri, E; Erbetta, A; Ragona, F; Freri, E; Fusco, L; Gobbi, G; Capovilla, G; Tassi, L; Giordano, L; Viri, M; Dalla Bernardina, B; Spreafico, R; Savoiardo, M

    2003-03-01

    Rasmussen's encephalitis (RE) is a rare, progressive, chronic encephalitis characterised by drug-resistant epilepsy, progressive hemiparesis and mental impairment. It typically involves only one cerebral hemisphere, which becomes atrophic. We present neuroradiological findings in 13 children with RE. MRI was performed in all patients, fluorodeoxyglucose positron-emission tomography (PET) in three, Tc-99m hexamethylpropylenamine oxime single-photon emission computed tomography (SPECT) in two and proton MR spectroscopy ((1)HMRS) in two. MRI showed progression of the hemisphere atrophy, always prevalent in the region primarily involved (13 patients), spread of the abnormal signal in white matter (11) and cortex (10) and progression of atrophy of the head of the caudate nucleus (nine). Associated secondary changes were: atrophy of the contralateral cerebellar hemisphere (in four patients), the ipsilateral hippocampus (in five) and the brain stem (in five). The earliest CT and MRI abnormalities, seen between 1 day and 4 months after the first seizure (in 12 patients examined, nine of whom had MRI) in one cerebral hemisphere included: high signal on T2-weighted images in the cortex (seven patients) and white matter (nine), cortical atrophy usually involving the frontoinsular region, with mild or severe enlargement of the lateral ventricle (eight) and moderate atrophy of the head of the caudate nucleus (seven). Cortical swelling in the early stage of the disease was recognisable only in two patients. PET revealed hypometabolism, SPECT decreased perfusion, and (1)HMRS reduction of N-acetylaspartate in the affected hemisphere. PET and SPECT were usually performed in the late stages and did not provide specific findings. MRI thus demonstrates the progression of RE and may suggest the diagnosis in the early stages, often before the appearance of neurological deficits. Early diagnosis of RE may be crucial for selecting patients for aggressive medical therapy or major surgical

  1. A novel evaluation of subcutaneous formulations by in vivo magnetic resonance imaging (MRI).

    PubMed

    Madhu, B; Elmroth, I; Lundgren, A; Abrahamsson, B; Soussi, B

    2002-03-01

    The applicability of magnetic resonance imaging (MRI) for non-invasive in vitro studies of parenteral vehicles without use of marker substances was investigated. A wide range of extended release (ER) formulations such as oils, a lipid emulsion, and water solutions of a cyclodextrin and block co-polymers were visualized in vitro and in vivo by a (1)H-MRI technique. The study included measurements in vitro in a beaker and by injections in pig flesh. In vivo studies were carried out in rats. The contrast of the vehicles vs the background material could be visualized and quantifications of vehicle dispersion and disappearance were performed on obtained in vivo data. A wide range of different vehicles suitable for s.c. ER delivery were tested, such as different oils, a lipid emulsion, and water solutions of a cyclodextrin and block co-polymers. The vehicle volume expansion in vivo was possible to follow. However, this was not generally applicable for all kinds of vehicle component. The tested co-polymers, Poloxamers, were one type of vehicle component that provides an excellent MRI signal. The in vitro tests predicted the suitability of this vehicle for in vivo MRI studies. In the in vivo study of the block co-polymer formulations the apparent vehicle volume increased to a peak value from an initial value close to the injected volume. Thereafter the volume diminished and no vehicle could be detected after 29 h after injection. MRI could be applied for measurements of the dispersion and disappearance of some vehicles at the site of injection after s.c. administration without use of contrast agents. PMID:11884217

  2. Assessment of MRI Parameters as Imaging Biomarkers for Radiation Necrosis in the Rat Brain

    SciTech Connect

    Wang Silun; Tryggestad, Erik; Zhou Tingting; Armour, Michael; Wen Zhibo; Fu Dexue; Ford, Eric; Zijl, Peter C.M. van; Zhou Jinyuan

    2012-07-01

    Purpose: Radiation necrosis is a major complication of radiation therapy. We explore the features of radiation-induced brain necrosis in the rat, using multiple MRI approaches, including T{sub 1}, T{sub 2}, apparent diffusion constant (ADC), cerebral blood flow (CBF), magnetization transfer ratio (MTR), and amide proton transfer (APT) of endogenous mobile proteins and peptides. Methods and Materials: Adult rats (Fischer 344; n = 15) were irradiated with a single, well-collimated X-ray beam (40 Gy; 10 Multiplication-Sign 10 mm{sup 2}) in the left brain hemisphere. MRI was acquired on a 4.7-T animal scanner at {approx}25 weeks' postradiation. The MRI signals of necrotic cores and perinecrotic regions were assessed with a one-way analysis of variance. Histological evaluation was accomplished with hematoxylin and eosin staining. Results: ADC and CBF MRI could separate perinecrotic and contralateral normal brain tissue (p < 0.01 and < 0.05, respectively), whereas T{sub 1}, T{sub 2}, MTR, and APT could not. MRI signal intensities were significantly lower in the necrotic core than in normal brain for CBF (p < 0.001) and APT (p < 0.01) and insignificantly higher or lower for T{sub 1}, T{sub 2}, MTR, and ADC. Histological results demonstrated coagulative necrosis within the necrotic core and reactive astrogliosis and vascular damage within the perinecrotic region. Conclusion: ADC and CBF are promising imaging biomarkers for identifying perinecrotic regions, whereas CBF and APT are promising for identifying necrotic cores.

  3. 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.

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

    PubMed

    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

  5. 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

  6. 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

  7. MRI 3D CISS- A Novel Imaging Modality in Diagnosing Trigeminal Neuralgia - A Review.

    PubMed

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

    2016-03-01

    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

  8. Advances in functional and structural imaging of the human lung using proton MRI.

    PubMed

    Miller, G Wilson; Mugler, John P; Sá, Rui C; Altes, Talissa A; Prisk, G Kim; Hopkins, Susan R

    2014-12-01

    The field of proton lung MRI is advancing on a variety of fronts. In the realm of functional imaging, it is now possible to use arterial spin labeling (ASL) and oxygen-enhanced imaging techniques to quantify regional perfusion and ventilation, respectively, in standard units of measurement. By combining these techniques into a single scan, it is also possible to quantify the local ventilation-perfusion ratio, which is the most important determinant of gas-exchange efficiency in the lung. To demonstrate potential for accurate and meaningful measurements of lung function, this technique was used to study gravitational gradients of ventilation, perfusion, and ventilation-perfusion ratio in healthy subjects, yielding quantitative results consistent with expected regional variations. Such techniques can also be applied in the time domain, providing new tools for studying temporal dynamics of lung function. Temporal ASL measurements showed increased spatial-temporal heterogeneity of pulmonary blood flow in healthy subjects exposed to hypoxia, suggesting sensitivity to active control mechanisms such as hypoxic pulmonary vasoconstriction, and illustrating that to fully examine the factors that govern lung function it is necessary to consider temporal as well as spatial variability. Further development to increase spatial coverage and improve robustness would enhance the clinical applicability of these new functional imaging tools. In the realm of structural imaging, pulse sequence techniques such as ultrashort echo-time radial k-space acquisition, ultrafast steady-state free precession, and imaging-based diaphragm triggering can be combined to overcome the significant challenges associated with proton MRI in the lung, enabling high-quality three-dimensional imaging of the whole lung in a clinically reasonable scan time. Images of healthy and cystic fibrosis subjects using these techniques demonstrate substantial promise for non-contrast pulmonary angiography and detailed

  9. 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

  10. 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

  11. 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

  12. Identifying quantitative imaging features of posterior fossa syndrome in longitudinal MRI.

    PubMed

    Spiteri, Michaela; Windridge, David; Avula, Shivaram; Kumar, Ram; Lewis, Emma

    2015-10-01

    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 ([Formula: see text]) when using this feature alone. PMID:26835496

  13. 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.

  14. Ovarian and tubal torsion: imaging findings on US, CT, and MRI.

    PubMed

    Lourenco, Ana P; Swenson, David; Tubbs, Robert J; Lazarus, Elizabeth

    2014-04-01

    Accurate diagnosis of adnexal torsion is often challenging, as clinical presentation is nonspecific and the differential for pelvic pain is broad. However, prompt diagnosis and treatment is critical to good clinical outcomes and preservation of the ovary and/or fallopian tube. Ultrasound (US) imaging is most frequently used to assess torsion. However, as computed tomography (CT) utilization in the emergency setting has increased, there are times when CT is the initial imaging test. Additionally, the nonspecific clinical presentation may initially be interpreted as gastrointestinal in etiology, where CT is the preferred exam. For these reasons, it is imperative to know the findings of adnexal torsion on CT as well as US. Magnetic resonance imaging (MRI) is helpful in cases where the diagnosis remains unclear and is particularly helpful in the young or pregnant patient with equivocal sonographic findings, as it provides excellent soft tissue contrast without ionizing radiation. This article will illustrate the findings of surgically confirmed ovarian and fallopian tube torsion on US, CT, and MRI, including those in the pregnant patient. Ovarian enlargement, adnexal mass, twisting of the vascular pedicle, edematous and heterogeneous appearance of the ovary, peripheral ovarian follicles, free fluid, uterine deviation towards the side of torsion, adnexal fat stranding, tubal dilatation, and decreased adnexal enhancement will be reviewed. Familiarity with the range of imaging findings across multiple modalities is key to improving the likelihood of timely diagnosis and therefore improved clinical outcomes. PMID:24078282

  15. 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

  16. Diffusion-weighted MRI for imaging cell death after cytotoxic or apoptosis-inducing therapy

    PubMed Central

    Papaevangelou, E; Almeida, G S; Jamin, Y; Robinson, S P; deSouza, N M

    2015-01-01

    Background: Non-invasive serial imaging is desirable to detect processes such as necrotic and apoptotic cell death in cancer patients undergoing treatment. This study investigated the use of diffusion-weighted (DW-) magnetic resonance imaging (MRI) for imaging cell death induced by either a cytotoxic drug (irinotecan), or the apoptosis-inducing agent birinapant, in human tumour xenografts in vivo. Methods: Nude mice bearing human SW620 colon carcinoma xenografts were treated with vehicle, irinotecan (50 mg kg−1) or birinapant (30 mg kg−1) for up to 5 days. DW-MRI was performed prior to and on days 1, 3 and 5 during treatment. Assessment of tumour apoptosis and necrosis ex vivo was used to validate the imaging findings. Results: Both irinotecan and birinapant induced significant tumour growth delay. Irinotecan induced a small increase in the tumour apparent diffusion coefficient (ADC) after 1 day, with a 20 and 30% increase at days 3 and 5 respectively. ADC was unchanged in the vehicle- and birinapant-treated tumours despite a growth delay in the latter. Histological analysis showed that irinotecan increased necrosis at days 3 and 5, and induced apoptosis after 1 day, compared with vehicle. Birinapant induced apoptosis after day 3, but had no effect on tumour necrosis. Conclusions: Tumour ADC changes after irinotecan treatment were associated with the induction of a mixture of necrotic and apoptotic cell death, whereas induction of apoptosis alone with birinapant was not sufficient to induce changes in tissue microstructure that were detectable with DW-MRI. ADC is a useful non-invasive biomarker for early detection of response to cytotoxic drugs, but false negatives may arise while detecting apoptotic response to birinapant. PMID:25880014

  17. 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

  18. 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.

  19. Multichannel single-photon-counting NIR imager for coregistration with MRI

    NASA Astrophysics Data System (ADS)

    Ntziachristos, Vasilis; Ma, Xuhui; Schnall, Mitchell; Chance, Britton

    1997-12-01

    An effective way to investigate the competence of NIR Imaging is to associate NIR images with ones from other, well established modalities, such as X-ray Mammography, Tomography or Magnetic Resonance Imaging (MRI). MRI is an excellent candidate for such an approach since besides having immense sensitivity and rendering great anatomical information, it also employs non-ionizing radiation. The simultaneous acquisition of MR and NIR data may afford very precise co-registration of images and investigate the potential and limitations of the technique. In return, by establishing confidence on the NIR Tomography capability, the MR specificity may be enhanced due to the additional information content of the simultaneous examination. We have developed a 24 X 8 source-detector multi-channel NIR imager and spectrometer based on the time-correlated single photon counting technique. The instrument is capable of operating as a stand-alone modality or coupled to an MR scanner. We have tested the instrument as a breast imager with volunteers and patients in the MR examination room. We have used specially designed soft compression plates bearing the optical fibers and the MR coils. The acquisition time has been optimized to be within the time limits of a typical MR breast examination protocol. We have obtained approximately 25 dB signal to noise ratio per sec of averaging time for 6 cm breast separation and sensitivity of absorption coefficient changes, following contrast agent administration, of the order of 10-3 cm-1. Additionally we demonstrate the use of the instrument as a stand-alone motor cortex activity imager/spectrometer.

  20. Multichannel single-photon-counting NIR imager for coregistration with MRI

    NASA Astrophysics Data System (ADS)

    Ntziachristos, Vasilis; Ma, XuHui; Schnall, Mitchell D.; Chance, Britton

    1998-01-01

    An effective way to investigate the competence of NIR Imaging is to associate NIR images with ones from other, well established modalities, such as X-ray Mammography, Tomography or Magnetic Resonance Imaging (MRI). MRI is an excellent candidate for such an approach since besides having immense sensitivity and rendering great anatomical information, it also employs non-ionizing radiation. The simultaneous acquisition of MR and NIR data may afford very precise co-registration of images and investigate the potential and limitations of the technique. In return, by establishing confidence on the NIR Tomography capability, the MR specificity may be enhanced due to the additional information content of the simultaneous examination. We have developed a 24 X 8 source-detector multi-channel NIR imager and spectrometer based on the time-correlated single photon counting technique. The instrument is capable of operating as a stand-alone modality or coupled to an MR scanner. We have tested the instrument as a breast imager with volunteers and patients in the MR examination room. We have used specially designed soft compression plates bearing the optical fibers and the MR coils. The acquisition time has been optimized to be within the time limits of a typical MR breast examination protocol. We have obtained approximately 25 dB signal to noise ratio per sec of averaging time for 6 cm breast separation and sensitivity of absorption coefficient changes, following contrast agent administration, of the order of 10-3 cm-1. Additionally we demonstrate the use of the instrument as a stand-alone motor cortex activity imager/spectrometer.

  1. 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.

  2. Factors in myocardial "perfusion" imaging with ultrafast MRI and Gd-DTPA administration.

    PubMed

    Burstein, D; Taratuta, E; Manning, W J

    1991-08-01

    Ultrafast magnetic resonance imaging (MRI) and first pass observation of an interstitial contrast agent are currently being used to study myocardial perfusion. Image intensity, however, is a function of several parameters, including the delivery of the contrast agent to the interstitium (coronary flow rate and diffusion into the interstitium) and the relaxation properties of the tissue (contrast agent concentration, proton exchange rates, and relative intra- and extracellular volume fractions). In this study, image intensity during gadopentetate dimeglumine (Gd-DTPA) administration with T1-weighted ultrafast MR imaging was assessed in an isolated heart preparation. With increasing Gd-DTPA concentration, the steady-state myocardial image intensity increased but the time to reach steady state remained unchanged, resulting in an increased slope of image intensity change. A range of physiologic perfusion pressures (and resulting coronary flow rates) had insignificant effects on kinetics of Gd-DTPA wash-in or steady-state image intensity, suggesting that diffusion of Gd-DTPA into the interstitium is the rate limiting step in image intensity change with this preparation. Following global ischemia and reperfusion, transmural differences in the slope of image intensity change were apparent. However, the altered steady-state image intensity (due to postischemic edema) makes interpretation of this finding difficult. The studies described here demonstrate that although Gd-DTPA administration combined with ultrafast imaging may be a sensitive indicator of perfusion abnormalities, factors other than perfusion will affect image intensity. Extensive studies will be required before image intensity with this protocol is fully understood. PMID:1775055

  3. 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

  4. X-ray properties of an anthropomorphic breast phantom for MRI and x-ray imaging

    NASA Astrophysics Data System (ADS)

    Freed, Melanie; Badal, Andreu; Jennings, Robert J.; de las Heras, Hugo; Myers, Kyle J.; Badano, Aldo

    2011-06-01

    The purpose of this study is to characterize the x-ray properties of a dual-modality, anthropomorphic breast phantom whose MRI properties have been previously evaluated. The goal of this phantom is to provide a platform for optimization and standardization of two- and three-dimensional x-ray and MRI breast imaging modalities for the purpose of lesion detection and discrimination. The phantom is constructed using a mixture of lard and egg whites, resulting in a variable, tissue-mimicking structure with separate adipose- and glandular-mimicking components. The phantom can be produced with either a compressed or uncompressed shape. Mass attenuation coefficients of the phantom materials were estimated using elemental compositions from the USDA National Nutrient Database for Standard Reference and the atomic interaction models from the Monte Carlo code PENELOPE and compared with human values from the literature. The image structure was examined quantitatively by calculating and comparing spatial covariance matrices of the phantom and patient mammography images. Finally, a computerized version of the phantom was created by segmenting a computed tomography scan and used to simulate x-ray scatter of the phantom in a mammography geometry. Mass attenuation coefficients of the phantom materials were within 20% and 15% of the values for adipose and glandular tissues, respectively, which is within the estimation error of these values. Matching was improved at higher energies (>20 keV). Tissue structures in the phantom have a size similar to those in the patient data, but are slightly larger on average. Correlations in the patient data appear to be longer than those in the phantom data in the anterior-posterior direction; however, they are within the error bars of the measurement. Simulated scatter-to-primary ratio values of the phantom images were as high as 85% in some areas and were strongly affected by the heterogeneous nature of the phantom. Key physical x-ray properties of

  5. 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. PMID:20648558

  6. 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

  7. 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. PMID:26530923

  8. 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

  9. Prediction of background parenchymal enhancement on breast MRI using mammography, ultrasonography, and diffusion-weighted imaging

    PubMed Central

    Kawamura, Akiko; Satake, Hiroko; Ishigaki, Satoko; Ikeda, Mitsuru; Kimura, Reiko; Shimamoto, Kazuhiro; Naganawa, Shinji

    2015-01-01

    ABSTRACT This retrospective study assessed the effects of menopausal status and menstrual cycle on background parenchymal enhancement (BPE) of breast magnetic resonance imaging (MRI), and investigated whether the degree of BPE can be predicted by findings of mammography, ultrasonography (US), and diffusion-weighted MR imaging (DWI). There were 160 study patients (80 premenopausal, 80 postmenopausal). Degree of BPE was classified into minimal, mild, moderate, or marked. Mammographic density was classified into fatty, scattered, heterogeneously dense, and extremely dense. BP echotexture on US and BP intensity on DWI were visually classified as homogeneous or heterogeneous. Apparent diffusion coefficient (ADC) values of normal breast tissue were measured. Associations of the degree of BPE with menopausal status, menstrual cycle, or imaging features were evaluated by univariate and multivariate analyses. No significant correlation was found between mammographic density and BPE (p=0.085), whereas menopausal status (p=0.000), BP echotexture (p=0.000), and BP intensity on DWI (p= 0.000), and ADC values (p=0.000) showed significant correlations with BPE. Multivariate analysis showed that postmenopausal status was an independent predictor of minimal BPE (p=0.002, OR=3.743). In premenopausal women, there was no significant correlation between menstrual cycle and BPE, whereas BP echotexture was an independent predictor of whether BPE was less than mild or greater than moderate (p=0.001, OR=26.575). BPE on breast MRI is associated with menopausal status and the findings of US and DWI. Because premenopausal women with heterogeneous BP echotexture may be predicted to show moderate or marked BPE, scheduling of breast MRI should preferentially be adjusted to the menstrual cycle. PMID:26412889

  10. 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

  11. 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

  12. Effect of Imaging Parameter Thresholds on MRI Prediction of Neoadjuvant Chemotherapy Response in Breast Cancer Subtypes.

    PubMed

    Lo, Wei-Ching; Li, Wen; 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

  13. A Quantitative MRI Method for Imaging Blood-Brain Barrier Leakage in Experimental Traumatic Brain Injury

    PubMed Central

    Watts, Lora Talley; Jiang, Zhao; Shen, Qiang; Li, Yunxia; Duong, Timothy Q.

    2014-01-01

    Blood-brain barrier (BBB) disruption is common following traumatic brain injury (TBI). Dynamic contrast enhanced (DCE) MRI can longitudinally measure the transport coefficient Ktrans which reflects BBB permeability. Ktrans measurements however are not widely used in TBI research because it is generally considered to be noisy and possesses low spatial resolution. We improved spatiotemporal resolution and signal sensitivity of Ktrans MRI in rats by using a high-sensitivity surface transceiver coil. To overcome the signal drop off profile of the surface coil, a pre-scan module was used to map the flip angle (B1 field) and magnetization (M0) distributions. A series of T1-weighted gradient echo images were acquired and fitted to the extended Kety model with reversible or irreversible leakage, and the best model was selected using F-statistics. We applied this method to study the rat brain one hour following controlled cortical impact (mild to moderate TBI), and observed clear depiction of the BBB damage around the impact regions, which matched that outlined by Evans Blue extravasation. Unlike the relatively uniform T2 contrast showing cerebral edema, Ktrans shows a pronounced heterogeneous spatial profile in and around the impact regions, displaying a nonlinear relationship with T2. This improved Ktrans MRI method is also compatible with the use of high-sensitivity surface coil and the high-contrast two-coil arterial spin-labeling method for cerebral blood flow measurement, enabling more comprehensive investigation of the pathophysiology in TBI. PMID:25478693

  14. A Novel liposomal nanoparticle for the imaging of amyloid plaque by MRI

    PubMed Central

    Tanifum, Eric A.; Ghaghada, Ketan; Vollert, Craig; Head, Elizabeth; Eriksen, Jason L.; Annapragada, Ananth

    2016-01-01

    Amyloid binding molecules with greater hydrophilicity than existing ligands were synthesized. The lead candidate ET6-21 bound amyloid fibrils, and amyloid deposits in dog brain and human brain tissue ex vivo. The ligand was used to prepare novel amyloid-targeted liposomal nanoparticles. The preparation was tested in the Tg2576 and TetO/APP mouse models of amyloid deposition. Gd chelates and Indocyanine green were included in the particles for visualization by MRI and near-infrared microscopy. Upon intravenous injection, the particles successfully traversed the blood-brain barrier in these mice, and bound to the plaques. Magnetic resonance imaging (T1-MRI) conducted 4 days after injection demonstrated elevated signal in the brains of mice with amyloid plaques present. No signal was observed in amyloid-negative mice, or in amyloid-positive mice injected with an untargeted version of the same agent. The MRI results were confirmed by immunohistochemical and fluorescent microscopic examination of mouse brain sections, showing colocalization of the fluorescent tags and amyloid deposits. PMID:27031484

  15. 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.

  16. Joint image reconstruction and motion parameter estimation for free-breathing navigator-gated cardiac MRI

    NASA Astrophysics Data System (ADS)

    Akçakaya, Mehmet; Basha, Tamer A.; Weingärtner, Sebastian; Nezafat, Reza

    2013-09-01

    We propose an acquisition and reconstruction technique for accelerated free-breathing cardiac MRI acquisitions. For the acquisition, a random undersampling pattern, including a fully-sampled center of k-space, is generated prospectively. The k-space lines specified by this undersampling pattern is acquired with respiratory navigating (NAV), where only the central k-space lines are acquired within the prespecified gating window. For the outer k-space lines, if the NAV signal corresponding to a k-space segment is outside the gating window, the segment is rejected, but not re-acquired. The reconstruction approach jointly estimates the underlying image using a compressed-sensing based approach, and the translational motion parameters for each segment for the outer k-space segments acquired outside the gating window. The feasibility of the approach is demonstrated in healthy adult subjects using whole-heart coronary MRI with a 3-fold accelerated random undersampling pattern. The proposed acquisition and reconstruction technique is compared to parallel imaging with uniform undersampling with 3-fold undersampling. The two techniques exhibit similar image quality with a shorter acquisition time for the proposed approach (4:25+/-0:31 minutes versus 6:52+/-0:19).

  17. Synthesis of brightly PEGylated luminescent magnetic upconversion nanophosphors for deep tissue and dual MRI imaging

    PubMed Central

    Chen, Hongyu; Qi, Bin; Moore, Thomas; Colvin, Daniel C.; Crawford, Thomas; Gore, John C.; Alexis, Frank; Mefford, O. Thompson; Anker, Jeffrey N.

    2014-01-01

    We developed a novel method to fabricate monodispersed biocompatible Yb/Er or Yb/Tm doped β-NaGdF4 upconversion phosphors using polyelectrolytes to prevent irreversible particle aggregation during the conversion of the precursor (Gd2O(CO3)2•H2O:Yb/Er or Yb/Tm) to β-NaGdF4:Yb/Er or Yb/Tm. The polyelectrolyte on the outer surface of nanophosphors also provided an amine tag for PEGylation. This method is also employed to fabricate PEGylated magnetic upconversion phosphors with Fe3O4 as the core and β-NaGdF4 as a shell. These magnetic upconversion nanophosphors have relatively high saturation magnetization (7.0 emu g-1) and magnetic susceptibility (1.7×10-2 emu g-1 Oe-1), providing them with large magnetophoretic mobilities. We have studied their magnetic properties for separation and controlled release in flow, their optical properties for cell labeling, deep tissue imaging, and their T1 and T2-weighted magnetic resonance imaging (MRI) relaxivities. The magnetic upconversion phosphors display both strong magnetophoresis, dual MRI imaging (r1=2.9 mM-1 s-1, r2=204 mM-1 s-1), and bright luminescence under 1 cm chicken breast. PMID:23828629

  18. Synthesis of brightly PEGylated luminescent magnetic upconversion nanophosphors for deep tissue and dual MRI imaging.

    PubMed

    Chen, Hongyu; Qi, Bin; Moore, Thomas; Colvin, Daniel C; Crawford, Thomas; Gore, John C; Alexis, Frank; Mefford, O Thompson; Anker, Jeffrey N

    2014-01-15

    A method is developed to fabricate monodispersed biocompatible Yb/Er or Yb/Tm doped β-NaGdF4 upconversion phosphors using polyelectrolytes to prevent irreversible particle aggregation during conversion of the precursor, Gd2 O(CO3 )2.H2 O:Yb/Er or Yb/Tm, to β-NaGdF4 :Yb/Er or Yb/Tm. The polyelectrolyte on the outer surface of nanophosphors also provided an amine tag for PEGylation. This method is also employed to fabricate PEGylated magnetic upconversion phosphors with Fe3 O4 as the core and β-NaGdF4 as a shell. These magnetic upconversion nanophosphors have relatively high saturation magnetization (7.0 emu g(-1) ) and magnetic susceptibility (1.7 × 10(-2) emu g(-1) Oe(-1) ), providing them with large magnetophoretic mobilities. The magnetic properties for separation and controlled release in flow, their optical properties for cell labeling, deep tissue imaging, and their T1 - and T2 -weighted magnetic resonance imaging (MRI) relaxivities are studied. The magnetic upconversion phosphors display both strong magnetophoresis, dual MRI imaging (r1 = 2.9 mM(-1) s(-1) , r2 = 204 mM(-1) s(-1) ), and bright luminescence under 1 cm chicken breast tissue. PMID:23828629

  19. A nano-sized PARACEST-fluorescence imaging contrast agent facilitates & validates in vivo CEST MRI detection of glioma

    PubMed Central

    Ali, Meser M; Bhuiyan, Mohammed PI; Janic, Branislava; Varma, Nadimpalli RS; Mikkelsen, Tom; Ewing, James R; Knight, Robert A; Pagel, Mark D; Arbab, Ali S

    2012-01-01

    Aim The authors have investigated the usefulness of in vivo chemical exchange saturation transfer MRI for detecting gliomas using a dual-modality imaging contrast agent. Materials & methods A paramagnetic chemical exchange saturation transfer MRI contrast agent, Eu-1,4,7,10-tetraazacclododecane-1,4,7,10-tetraacetic acid-Gly4 and a fluorescent agent, DyLight® 680, were conjugated to a generation 5 polyamidoamine dendrimer to create the dual-modality, nano-sized imaging contrast agent. Results The agent was detected with in vivo chemical exchange saturation transfer MRI in an U87 glioma model. These results were validated using in vivo and ex vivo fluorescence imaging. Conclusion This study demonstrated the merits of using a nano-sized imaging contrast agent for detecting gliomas and using a dual-modality agent for detecting gliomas at different spatial scales. PMID:22891866

  20. Assessment of Geometrical Accuracy of Multimodal Images Used for Treatment Planning in Stereotactic Radiotherapy and Radiosurgery: CT, MRI and PET

    SciTech Connect

    Garcia-Garduno, O. A.; Larraga-Gutierrez, J. M.; Celis, M. A.; Suarez-Campos, J. J.; Rodriguez-Villafuerte, M.; Martinez-Davalos, A.

    2006-09-08

    An acrylic phantom was designed and constructed to assess the geometrical accuracy of CT, MRI and PET images for stereotactic radiotherapy (SRT) and radiosurgery (SRS) applications. The phantom was suited for each image modality with a specific tracer and compared with CT images to measure the radial deviation between the reference marks in the phantom. It was found that for MRI the maximum mean deviation is 1.9 {+-} 0.2 mm compared to 2.4 {+-} 0.3 mm reported for PET. These results will be used for margin outlining in SRS and SRT treatment planning.

  1. 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

  2. Robust fluoroscopic tracking of fiducial markers: exploiting the spatial constraints.

    PubMed

    Li, Rui; Sharp, Gregory

    2013-03-21

    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 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 a multiple hypothesis tracking (MHT) algorithm which is denoted by MHT, Tang et al (2007 Phys. Med. Biol. 52 4081-98). 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

  3. Robust fluoroscopic tracking of fiducial markers: exploiting the spatial constraints

    NASA Astrophysics Data System (ADS)

    Li, Rui; Sharp, Gregory

    2013-03-01

    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 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 a multiple hypothesis tracking (MHT) algorithm which is denoted by MHT, Tang et al (2007 Phys. Med. Biol. 52 4081-98). 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 (

  4. Cardiac Amyloidosis: Typical Imaging Findings and Diffuse Myocardial Damage Demonstrated by Delayed Contrast-Enhanced MRI

    SciTech Connect

    Sueyoshi, Eijun Sakamoto, Ichiro; Okimoto, Tomoaki; Hayashi, Kuniaki; Tanaka, Kyouei; Toda, Genji

    2006-08-15

    Amyloidosis is a rare systemic disease. However, involvement of the heart is a common finding and is the most frequent cause of death in amyloidosis. We report the sonographic, scintigraphic, and MRI features of a pathologically proven case of cardiac amyloidosis. Delayed contrast-enhanced MR images, using an inversion recovery prepped gradient-echo sequence, revealed diffuse enhancement in the wall of both left and right ventricles. This enhancement suggested expansion of the extracellular space of the myocardium caused by diffuse myocardial necrosis secondary to deposition of amyloid.

  5. 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.

  6. Mesenteric inflammatory myofibroblastic tumor: MRI and CT imaging correlated to anatomical pathology.

    PubMed

    Kirchgesner, Th; Danse, E; Sempoux, Ch; Annet, L; Dragean, Ch Anca; Trefois, P; Abbes Orabi, N; Kartheuser, A

    2014-01-01

    Inflammatory myofibroblastic tumor (IMT) is a rare tumor, classified by WHO of intermediate biological potential with tendency for local recurrence and small risk for distant metastasis. Histologically IMT is a mixture of inflamma- tory cells and myofibroblastic spindle cells proliferation. To our knowledge there is no MRI description of mesenteric IMT in the literature. We would like to emphasize the correlation between medical imaging and anatomical pathology based on our experience of a mesenteric IMT in a 28-year-old patient. PMID:25597213

  7. A Rotational Cylindrical fMRI Phantom for Image Quality Control

    PubMed Central

    2015-01-01

    Purpose A novel phantom for image quality testing for functional magnetic resonance imaging (fMRI) scans is described. Methods The cylindrical, rotatable, ~4.5L phantom, with eight wedge-shaped compartments, is used to simulate rest and activated states. The compartments contain NiCl2 doped agar gel with alternating concentrations of agar (1.4%, 1.6%) to produce T1 and T2 values approximating brain grey matter. The Jacard index was used to compare the image distortions for echo planar imaging (EPI) and gradient recalled echo (GRE) scans. Contrast to noise ratio (CNR) was compared across the imaging volume for GRE and EPI. Results The mean T2 for the two agar concentrations were found to be 106.5±4.8, 94.5±4.7 ms, and T1 of 1500±40 and 1485±30 ms, respectively. The Jacard index for GRE was generally found to be higher than for EPI (0.95 versus 0.8). The CNR varied from 20 to 50 across the slices and echo times used for EPI scans, and from 20 to 40 across the slices for the GRE scans. The phantom provided a reproducible CNR over 25 days. Conclusions The phantom provides a quantifiable signal change over a head-size imaging volume with EPI and GRE sequences, which was used for image quality assessment. PMID:26625264

  8. Imaging of Intratumoral Inflammation during Oncolytic Virotherapy of Tumors by 19F-Magnetic Resonance Imaging (MRI)

    PubMed Central

    Hess, Michael; Hofmann, Elisabeth; Seubert, Carolin; Langbein-Laugwitz, Johanna; Gentschev, Ivaylo; Sturm, Volker Jörg Friedrich; Ye, Yuxiang; Kampf, Thomas; Jakob, Peter Michael; Szalay, Aladar A.

    2013-01-01

    Background Oncolytic virotherapy of tumors is an up-coming, promising therapeutic modality of cancer therapy. Unfortunately, non-invasive techniques to evaluate the inflammatory host response to treatment are rare. Here, we evaluate 19F magnetic resonance imaging (MRI) which enables the non-invasive visualization of inflammatory processes in pathological conditions by the use of perfluorocarbon nanoemulsions (PFC) for monitoring of oncolytic virotherapy. Methodology/Principal Findings The Vaccinia virus strain GLV-1h68 was used as an oncolytic agent for the treatment of different tumor models. Systemic application of PFC emulsions followed by 1H/19F MRI of mock-infected and GLV-1h68-infected tumor-bearing mice revealed a significant accumulation of the 19F signal in the tumor rim of virus-treated mice. Histological examination of tumors confirmed a similar spatial distribution of the 19F signal hot spots and CD68+-macrophages. Thereby, the CD68+-macrophages encapsulate the GFP-positive viral infection foci. In multiple tumor models, we specifically visualized early inflammatory cell recruitment in Vaccinia virus colonized tumors. Furthermore, we documented that the 19F signal correlated with the extent of viral spreading within tumors. Conclusions/Significance These results suggest 19F MRI as a non-invasive methodology to document the tumor-associated host immune response as well as the extent of intratumoral viral replication. Thus, 19F MRI represents a new platform to non-invasively investigate the role of the host immune response for therapeutic outcome of oncolytic virotherapy and individual patient response. PMID:23441176

  9. Multiple system atrophy: natural history, MRI morphology, and dopamine receptor imaging with 123IBZM-SPECT.

    PubMed Central

    Schulz, J B; Klockgether, T; Petersen, D; Jauch, M; Müller-Schauenburg, W; Spieker, S; Voigt, K; Dichgans, J

    1994-01-01

    Sixteen patients with a clinical diagnosis of probable multiple system atrophy (MSA) were examined clinically by MRI and by 123I-iodobenzamide single photon emission computed tomography (IBZM-SPECT). The clinical records of another 16 patients were also analysed retrospectively. On the basis of their clinical presentation, patients were subdivided into those with prominent parkinsonism (MSA-P, n = 11) and those with prominent cerebellar ataxia (MSA-C, n = 21). Autonomic symptoms were present in all patients and preceded the onset of motor symptoms in 63% of patients. Calculated median lifetime and the median time to become wheelchair bound after onset of disease were significantly shorter for MSA-P than for MSA-C (lifetime: 4.0 v 9.1 years; wheelchair: 3.1 vs 5.0 years) suggesting a better prognosis for cerebellar patients. A significant loss of striatal dopamine receptors (below 2 SD threshold) was detected by IBZM-SPECT in 63% of the patients (56% below 2.5 SD threshold). There was no difference between patients with MSA-C and those with MSA-P in the proportion with significant receptor loss and the extent of dopamine receptor loss. Planimetric MRI evaluation showed cerebellar and brainstem atrophy in both groups. Atrophy was more pronounced in patients with MSA-C than in those with MSA-P. Pontocerebellar hyperintensities and putaminal hypointensities on T2 weighted MRI were found in both groups. Pontocerebellar signal abnormalities were more pronounced in MSA-C than in MSA-P, whereas the rating scores for area but not for intensity of putaminal abnormalities were higher in MSA-P. MRI and IBZM-SPECT provide in vivo evidence for combined basal ganglia and pontocerebellar involvement in almost all patients in this series. Images PMID:8089667

  10. 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

  11. 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. PMID:25689595

  12. Content-based image retrieval utilizing explicit shape descriptors: applications to breast MRI and prostate histopathology

    NASA Astrophysics Data System (ADS)

    Sparks, Rachel; Madabhushi, Anant

    2011-03-01

    Content-based image retrieval (CBIR) systems, in the context of medical image analysis, allow for a user to compare a query image to previously archived database images in terms of diagnostic and/or prognostic similarity. CBIR systems can therefore serve as a powerful computerized decision support tool for clinical diagnostics and also serve as a useful learning tool for medical students, residents, and fellows. An accurate CBIR system relies on two components, (1) image descriptors which are related to a previously defined notion of image similarity and (2) quantification of image descriptors in order to accurately characterize and capture the a priori defined image similarity measure. In many medical applications, the morphology of an object of interest (e.g. breast lesions on DCE-MRI or glands on prostate histopathology) may provide important diagnostic and prognostic information regarding the disease being investigated. Morphological attributes can be broadly categorized as being (a) model-based (MBD) or (b) non-model based (NMBD). Most computerized decision support tools leverage morphological descriptors (e.g. area, contour variation, and compactness) which belong to the latter category in that they do not explicitly model morphology for the object of interest. Conversely, descriptors such as Fourier descriptors (FDs) explicitly model the object of interest. In this paper, we present a CBIR system that leverages a novel set of MBD called Explicit Shape Descriptors (ESDs) which accurately describe the similarity between the morphology of objects of interest. ESDs are computed by: (a) fitting shape models to objects of interest, (b) pairwise comparison between shape models, and (c) a nonlinear dimensionality reduction scheme to extract a concise set of morphological descriptors in a reduced dimensional embedding space. We utilized our ESDs in the context of CBIR in three datasets: (1) the synthetic MPEG-7 Set B containing 1400 silhouette images, (2) DCE-MRI of

  13. Towards fluoroscopic respiratory gating for lung tumours without radiopaque markers

    NASA Astrophysics Data System (ADS)

    Berbeco, Ross I.; Mostafavi, Hassan; Sharp, Gregory C.; Jiang, Steve B.

    2005-10-01

    Due to the risk of pneumothorax, many clinicians are reluctant to implant radiopaque markers within patients' lungs for the purpose of radiographic or fluoroscopic tumour localization. We propose a method of gated therapy using fluoroscopic information without the implantation of radiopaque markers. The method presented here does not rely on any external motion signal either. Breathing phase information is found by analysing the fluoroscopic intensity fluctuations in the lung. As the lungs fill/empty, the radiological pathlength through them shortens/lengthens, giving brighter/darker fluoroscopic intensities. The phase information is combined with motion-enhanced template matching to turn the beam on when the tumour is in the desired location. A study based on patient data is presented to demonstrate the feasibility of this procedure. The resulting beam-on pattern is similar to that produced by an external gating system. The only discrepancies occur briefly and at the gate edges.

  14. 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

  15. 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

  16. Choosing Between MRI and CT Imaging in the Adult with Congenital Heart Disease.

    PubMed

    Bonnichsen, Crystal; Ammash, Naser

    2016-05-01

    Improvements in the outcomes of surgical and catheter-based interventions and medical therapy have led to a growing population of adult patients with congenital heart disease. Adult patients with previously undiagnosed congenital heart disease or those previously palliated or repaired may have challenging echocardiographic examinations. Understanding the distinct anatomic and hemodynamic features of the congenital anomaly and quantifying ventricular function and valvular dysfunction plays an important role in the management of these patients. Rapid advances in imaging technology with magnetic resonance imaging (MRI) and computed tomography angiography (CTA) allow for improved visualization of complex cardiac anatomy in the evaluation of this unique patient population. Although echocardiography remains the most widely used imaging tool to evaluate congenital heart disease, alternative and, at times, complimentary imaging modalities should be considered. When caring for adults with congenital heart disease, it is important to choose the proper imaging study that can answer the clinical question with the highest quality images, lowest risk to the patient, and in a cost-efficient manner. PMID:27002621

  17. 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.

  18. Development of functional imaging in the human brain (fMRI); the University of Minnesota experience.

    PubMed

    Uğurbil, Kâmil

    2012-08-15

    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 become functional earlier, they would have been started earlier as well. We were aware of the competing effort at the Massachusetts General Hospital (MGH) and we knew that they had been informed of our initiative in Minneapolis to develop fMRI. We had positive results certainly by August 1991 annual meeting of the Society of Magnetic Resonance in Medicine (SMRM). 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 rejection by Nature in our case. Thus, 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

  19. 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

  20. A spatio-temporal detective quantum efficiency and its application to fluoroscopic systems

    SciTech Connect

    Friedman, S. N.; Cunningham, I. A.

    2010-11-15

    Purpose: Fluoroscopic x-ray imaging systems are used extensively in spatio-temporal detection tasks and require a spatio-temporal description of system performance. No accepted metric exists that describes spatio-temporal fluoroscopic performance. The detective quantum efficiency (DQE) is a metric widely used in radiography to quantify system performance and as a surrogate measure of patient ''dose efficiency.'' It has been applied previously to fluoroscopic systems with the introduction of a temporal correction factor. However, the use of a temporally-corrected DQE does not provide system temporal information and it is only valid under specific conditions, many of which are not likely to be satisfied by suboptimal systems. The authors propose a spatio-temporal DQE that describes performance in both space and time and is applicable to all spatio-temporal quantum-based imaging systems. Methods: The authors define a spatio-temporal DQE (two spatial-frequency axes and one temporal-frequency axis) in terms of a small-signal spatio-temporal modulation transfer function (MTF) and spatio-temporal noise power spectrum (NPS). Measurements were made on an x-ray image intensifier-based bench-top system using continuous fluoroscopy with an RQA-5 beam at 3.9 {mu}R/frame and hardened 50 kVp beam (0.8 mm Cu filtration added) at 1.9 {mu}R/frame. Results: A zero-frequency DQE value of 0.64 was measured under both conditions. Nonideal performance was noted at both larger spatial and temporal frequencies; DQE values decreased by {approx}50% at the cutoff temporal frequency of 15 Hz. Conclusions: The spatio-temporal DQE enables measurements of decreased temporal system performance at larger temporal frequencies analogous to previous measurements of decreased (spatial) performance. This marks the first time that system performance and dose efficiency in both space and time have been measured on a fluoroscopic system using DQE and is the first step toward the generalized use of DQE on

  1. Monte Carlo simulation of a prototypical patient dosimetry system for fluoroscopic procedures

    NASA Astrophysics Data System (ADS)

    Goertz, Lukas; Tsiamas, Panagiotis; Karellas, Andrew; Sajo, Erno; Zygmanski, Piotr

    2015-08-01

    The purpose of this study is to investigate feasibility of a novel real-time dosimetry method for fluoroscopically guided interventions utilizing thin-film detector arrays in several potential locations with respect to the patient and x-ray equipment. We employed Monte Carlo (MC) simulation to establish the fluoroscopic beam model to determine dosimetric quantities directly from measured doses in thin-film detector arrays at three positions: A—attached to the x-ray source, B—on the couch under the patient and C—attached to the fluoroscopic imager. Next, we developed a calibration method to determine skin dose at the entry of the beam ({{D}\\text{entr}} ) as well as the dose distribution along each ray of the beam in a water-equivalent patient model. We utilized the concept of water-equivalent thickness to determine the dose inside the patient based on doses measured outside of the patient by the thin-film detector array layers: (a) A, (b) B, or (c) B and C. In the process of calibration we determined a correction factor that characterizes the material-specific response of the detector, backscatter factor and attenuation factor for slab water phantoms of various thicknesses. Application of this method to an anthropomorphic phantom showed accuracy of about 1% for {{D}\\text{entr}} and up to about 10% for integral dose along the beam path when compared to a direct simulation of dose by MC.

  2. Monte Carlo simulation of a prototypical patient dosimetry system for fluoroscopic procedures.

    PubMed

    Goertz, Lukas; Tsiamas, Panagiotis; Karellas, Andrew; Sajo, Erno; Zygmanski, Piotr

    2015-08-01

    The purpose of this study is to investigate feasibility of a novel real-time dosimetry method for fluoroscopically guided interventions utilizing thin-film detector arrays in several potential locations with respect to the patient and x-ray equipment. We employed Monte Carlo (MC) simulation to establish the fluoroscopic beam model to determine dosimetric quantities directly from measured doses in thin-film detector arrays at three positions: A-attached to the x-ray source, B-on the couch under the patient and C-attached to the fluoroscopic imager. Next, we developed a calibration method to determine skin dose at the entry of the beam ([Formula: see text]) as well as the dose distribution along each ray of the beam in a water-equivalent patient model. We utilized the concept of water-equivalent thickness to determine the dose inside the patient based on doses measured outside of the patient by the thin-film detector array layers: (a) A, (b) B, or (c) B and C. In the process of calibration we determined a correction factor that characterizes the material-specific response of the detector, backscatter factor and attenuation factor for slab water phantoms of various thicknesses. Application of this method to an anthropomorphic phantom showed accuracy of about 1% for [Formula: see text] and up to about 10% for integral dose along the beam path when compared to a direct simulation of dose by MC. PMID:26184743

  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. 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.

  5. Protein MRI contrast agent with unprecedented metal selectivity and sensitivity for liver cancer imaging

    PubMed Central

    Yang, Hua; Qiao, Jingjuan; Pu, Fan; Jiang, Jie; Hubbard, Kendra; Hekmatyar, Khan; Langley, Jason; Salarian, Mani; Long, Robert C.; Bryant, Robert G.; Hu, Xiaoping Philip; Grossniklaus, Hans E.; Liu, Zhi-Ren; Yang, Jenny J.

    2015-01-01

    With available MRI techniques, primary and metastatic liver cancers that are associated with high mortality rates and poor treatment responses are only diagnosed at late stages, due to the lack of highly sensitive contrast agents without Gd3+ toxicity. We have developed a protein contrast agent (ProCA32) that exhibits high stability for Gd3+ and a 1011-fold greater selectivity for Gd3+ over Zn2+ compared with existing contrast agents. ProCA32, modified from parvalbumin, possesses high relaxivities (r1/r2: 66.8 mmol−1⋅s−1/89.2 mmol−1⋅s−1 per particle). Using T1- and T2-weighted, as well as T2/T1 ratio imaging, we have achieved, for the first time (to our knowledge), robust MRI detection of early liver metastases as small as ∼0.24 mm in diameter, much smaller than the current detection limit of 10–20 mm. Furthermore, ProCA32 exhibits appropriate in vivo preference for liver sinusoidal spaces and pharmacokinetics for high-quality imaging. ProCA32 will be invaluable for noninvasive early detection of primary and metastatic liver cancers as well as for monitoring treatment and guiding therapeutic interventions, including drug delivery. PMID:25971726

  6. 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

  7. A framework for accurate determination of the T2 distribution from multiple echo magnitude MRI images

    NASA Astrophysics Data System (ADS)

    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.

  8. Magnetosomes, biogenic magnetic nanomaterials for brain molecular imaging with 17.2 T MRI scanner.

    PubMed

    Mériaux, Sébastien; Boucher, Marianne; Marty, Benjamin; Lalatonne, Yoann; Prévéral, Sandra; Motte, Laurence; Lefèvre, Christopher T; Geffroy, Françoise; Lethimonnier, Franck; Péan, Michel; Garcia, Daniel; Adryanczyk-Perrier, Géraldine; Pignol, David; Ginet, Nicolas

    2015-05-01

    The fast development of sensitive molecular diagnostic tools is currently paving the way for a personalized medicine. A new class of ultrasensitive magnetic resonance imaging (MRI) T₂-contrast agents based on magnetosomes, magnetite nanocrystals biomineralized by magnetotactic bacteria, is proposed here. The contrast agents can be injected into the blood circulation and detected in the picomolar range. Purified magnetosomes are water-dispersible and stable within physiological conditions and exhibit at 17.2 T a transverse relaxivity r₂ four times higher than commercial ferumoxide. The subsequent gain in sensitivity by T₂(*) -weighted imaging at 17.2 T of the mouse brain vasculature is evidenced in vivo after tail vein injection of magnetosomes representing a low dose of iron (20 μmoliron kg(-1)), whereas no such phenomenon with the same dose of ferumoxide is observed. Preclinical studies of human pathologies in animal models will benefit from the combination of high magnetic field MRI with sensitive, low dose, easy-to-produce biocompatible contrast agents derived from bacterial magnetosomes. PMID:25676134

  9. 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. PMID:27034951

  10. Fluoroscopically Guided Balloon Dilation for Postintubation Tracheal Stenosis

    SciTech Connect

    Lee, Woong Hee; Kim, Jin Hyoung Park, Jung-Hun

    2013-10-15

    Purpose: Little was known about the safety and long-term efficacy of fluoroscopically guided balloon dilation for postintubation tracheal stenosis. The purpose of this study was to evaluate the safety and long-term efficacy of fluoroscopically guided balloon dilation in patients with postintubation tracheal stenosis. Methods: From February 2000 to November 2010, 14 patients underwent fluoroscopically guided balloon dilation for postintubation tracheal stenosis. Technical success, clinical success, and complications were evaluated. Patients were followed up for recurrent symptoms. Results: In all patients, fluoroscopically guided balloon dilation was technically and clinically successful with no major complications. Following the initial procedure, six patients (43 %) remained asymptomatic during a follow-up period. Obstructive symptoms recurred in eight patients (57 %) within 6 months (mean, 1.7 months), who were treated with repeat balloon dilation (n = 4) and other therapies. Of the four patients who underwent repeat balloon dilation, three became asymptomatic. One patient became asymptomatic after a third balloon dilation. On long-term (mean, 74 months) follow-up, 71 % of patients experienced relief of symptoms following fluoroscopically guided balloon dilation. Conclusions: Fluoroscopically guided balloon dilation may be safe, is easy to perform, and resulted in effective treatment in patients with postintubation tracheal stenosis.

  11. Diffusion-weighted imaging and dynamic contrast-enhanced MRI in assessing response and recurrent disease in gynaecological malignancies.

    PubMed

    Hameeduddin, Ayshea; Sahdev, Anju

    2015-01-01

    Magnetic resonance imaging (MRI) has an established role in imaging pelvic gynaecological malignancies. It is routinely used in staging endometrial and cervical cancer, characterizing adnexal masses, selecting optimal treatment, monitoring treatment and detecting recurrent disease. MRI has also been shown to have an excellent performance and an evolving role in surveillance of patients after chemoradiotherapy in cervical cancer, post-trachelectomy, detecting early recurrence and planning exenterative surgery in isolated central recurrences in both cervical and endometrial cancer and in young patients on surveillance for medically managed endometrial cancer. However, conventional MRI still has limitations when the morphological appearance of early recurrent or residual disease overlaps with normal pelvic anatomy or treatment effects in the pelvis. In particular, after chemoradiotherapy for cervical cancer, distinguishing between radiotherapy changes and residual or early recurrent disease within the cervix or the vaginal vault can be challenging on conventional MRI alone. Therefore, there is an emerging need for functional imaging to overcome these limitations. The purpose of this paper is to discuss the emerging functional MRI techniques and their applications in predicting treatment response, detecting residual disease and early recurrent disease to optimize the treatment options available using diffusion-weighted imaging and dynamic contrast enhancement particularly in cervical and endometrial cancer. PMID:25889065

  12. Interleaved EPI based fMRI improved by multiplexed sensitivity encoding (MUSE) and simultaneous multi-band imaging.

    PubMed

    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

  13. 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

  14. Heart MRI

    MedlinePlus

    ... an imaging method that uses powerful magnets and radio waves to create pictures of the heart. It does ... radiation involved in MRI. The magnetic fields and radio waves used during the scan have not been shown ...

  15. Influence of multichannel combination, parallel imaging and other reconstruction techniques on MRI noise characteristics.

    PubMed

    Dietrich, Olaf; Raya, José G; Reeder, Scott B; Ingrisch, Michael; Reiser, Maximilian F; Schoenberg, Stefan O

    2008-07-01

    The statistical properties of background noise such as its standard deviation and mean value are frequently used to estimate the original noise level of the acquired data. This requires the knowledge of the statistical intensity distribution of the background signal, that is, the probability density of the occurrence of a certain signal intensity. The influence of many new MRI techniques and, in particular, of various parallel-imaging methods on the noise statistics has neither been rigorously investigated nor experimentally demonstrated yet. In this study, the statistical distribution of background noise was analyzed for MR acquisitions with a single-channel and a 32-channel coil, with sum-of-squares (SoS) and spatial-matched-filter (SMF) data combination, with and without parallel imaging using k-space and image-domain algorithms, with real-part and conventional magnitude reconstruction and with several reconstruction filters. Depending on the imaging technique, the background noise could be described by a Rayleigh distribution, a noncentral chi-distribution or the positive half of a Gaussian distribution. In particular, the noise characteristics of SoS-reconstructed multichannel acquisitions (with k-space-based parallel imaging or without parallel imaging) differ substantially from those with image-domain parallel imaging or SMF combination. These effects must be taken into account if mean values or standard deviations of background noise are employed for data analysis such as determination of local noise levels. Assuming a Rayleigh distribution as in conventional MR images or a noncentral chi-distribution for all multichannel acquisitions is invalid in general and may lead to erroneous estimates of the signal-to-noise ratio or the contrast-to-noise ratio. PMID:18440746

  16. Positional pelvic organ prolapse (POP) evaluation using open, weight-bearing magnetic resonance imaging (MRI)

    PubMed Central

    Friedman, Boris; Stothers, Lynn; Lazare, Darren; Macnab, Andrew

    2015-01-01

    Introduction: Magnetic resonance imaging (MRI) of patients with pelvic organ prolapse (POP) is completed in the supine position. Open magnetic resonance imaging (MRO) uses vertical magnets, allowing imaging in a variety of upright postures. This pilot study used MRO to evaluate the change of prolapse in different positions compared to non-prolapsed images. Methods: In total, 11 women (6 POP, 5 controls) aged 24 to 65 years had 12 MRO images (midline sagittal pelvic line) consecutively when supine, sitting and standing with a full and empty bladder. Lengths between the lowest point of the bladder to the pubococcygeal (PC) and pubopromontoreal (PP) lines in each image were compared, and the ratio of bladder area under the PC and PP lines to the total bladder area. Results: Significant elongation between the PC line and lowest point of the bladder was evident in subjects with POP comparing supine and standing images (p = 0.03), but not controls (p = 0.07). Similarly, this axis was significantly longer in cystocele subjects versus controls only in the standing position. Bladder area under the PC line was significantly increased between supine and standing positions only among subjects with cystocele (p < 0.01), and significantly larger among the study group in the standing position (p < 0.005), less significant in the supine position (p = 0.015), and not significant in the sitting position (p = 0.3). Conclusions: MRO imaging allows us to investigate the effects of upright position and weight bearing on the staging of POP. Imaging patients when sitting and standing identified that significant changes occur in the maximal descent of the bladder. PMID:26225170

  17. 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

  18. Post-mortem CT and MRI: appropriate post-mortem imaging appearances and changes related to cardiopulmonary resuscitation.

    PubMed

    Offiah, Curtis E; 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

  19. 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.

  20. Image-Guided Radio-Frequency Gain Calibration for High-Field MRI

    PubMed Central

    Breton, Elodie; McGorty, KellyAnne; Wiggins, Graham C.; Axel, Leon; Kim, Daniel

    2010-01-01

    High-field (≥ 3T) MRI provides a means to increase the signal-to-noise ratio, due to its higher tissue magnetization compared with 1.5T. However, both the static magnetic field (B0) and the transmit radio-frequency (RF) field (B1+) inhomogeneities are comparatively higher than those at 1.5T. These challenging factors at high-field strengths make it more difficult to accurately calibrate the transmit RF gain using standard RF calibration procedures. An image-based RF calibration procedure was therefore developed, in order to accurately calibrate the transmit RF gain within a specific region-of-interest (ROI). Using a single-shot ultra-fast gradient echo pulse sequence with centric k-space reordering, a series of “saturation-no-recovery” images was acquired by varying the flip angle of the preconditioning pulse. In the resulting images, the signal null occurs in regions where the flip angle of the preconditioning pulse is 90°. For a given ROI, the mean signal can be plotted as a function of the nominal flip angle, and the resulting curve can be used to quantitatively identify the signal null. This image-guided RF calibration procedure was evaluated through phantom and volunteer imaging experiments at 3T and 7T. The image-guided RF calibration results in vitro were consistent with standard B0 and B1+ maps. The standard automated RF calibration procedure produced approximately 20% and 15–30% relative error in the transmit RF gain in the left kidney at 3T and brain at 7T, respectively. For initial application, a T2 mapping pulse sequence was applied at 7T. The T2 measurements in the thalamus at 7T were 60.6 ms and 48.2 ms using the standard and image-guided RF calibration procedures, respectively. This rapid, image-guided RF calibration procedure can be used to optimally calibrate the flip angle for a given ROI and thus minimize measurement errors for quantitative MRI and MR spectroscopy. PMID:20014333

  1. 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

  2. Clinical and magnetic resonance imaging (MRI) findings in 26 dogs with canine osseous-associated cervical spondylomyelopathy

    PubMed Central

    Murthy, Vishal D.; Gaitero, Luis; Monteith, Gabrielle

    2014-01-01

    The potential link between degenerative changes seen on magnetic resonance imaging (MRI) in osseous-associated cervical spondylomyelopathy (OA-CSM) and clinical signs has not been explored. Our goal was to retrospectively evaluate MRI findings, while investigating potential correlations between these changes, signalment, and clinical signs. Twenty-six dogs diagnosed with OA-CSM were included in the study. Clinical signs were converted into a Modified Frankel Score (MFS) and MRI findings were assessed and graded. Giant breeds had multiple compressed sites and presented at a younger age than large breeds, suggesting a different underlying pathophysiology. Spinal cord compression, most commonly bilateral, was present in 36.8% of intervertebral spaces. Synovial fluid loss and articular process sclerosis were the most common degenerative changes. Most dogs showed identical MFS scores, and no significant correlations were found between MFS and MRI changes. More detailed functional scales should be used to investigate this in the future. PMID:24489397

  3. Clinical and magnetic resonance imaging (MRI) findings in 26 dogs with canine osseous-associated cervical spondylomyelopathy.

    PubMed

    Murthy, Vishal D; Gaitero, Luis; Monteith, Gabrielle

    2014-02-01

    The potential link between degenerative changes seen on magnetic resonance imaging (MRI) in osseous-associated cervical spondylomyelopathy (OA-CSM) and clinical signs has not been explored. Our goal was to retrospectively evaluate MRI findings, while investigating potential correlations between these changes, signalment, and clinical signs. Twenty-six dogs diagnosed with OA-CSM were included in the study. Clinical signs were converted into a Modified Frankel Score (MFS) and MRI findings were assessed and graded. Giant breeds had multiple compressed sites and presented at a younger age than large breeds, suggesting a different underlying pathophysiology. Spinal cord compression, most commonly bilateral, was present in 36.8% of intervertebral spaces. Synovial fluid loss and articular process sclerosis were the most common degenerative changes. Most dogs showed identical MFS scores, and no significant correlations were found between MFS and MRI changes. More detailed functional scales should be used to investigate this in the future. PMID:24489397

  4. 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.

  5. 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

  6. 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

  7. 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

  8. Evaluation of three MRI-based anatomical priors for quantitative PET brain imaging.

    PubMed

    Vunckx, Kathleen; Atre, Ameya; Baete, Kristof; Reilhac, Anthonin; Deroose, Christophe M; Van Laere, Koen; Nuyts, Johan

    2012-03-01

    In emission tomography, image reconstruction and therefore also tracer development and diagnosis may benefit from the use of anatomical side information obtained with other imaging modalities in the same subject, as it helps to correct for the partial volume effect. One way to implement this, is to use the anatomical image for defining the a priori distribution in a maximum-a-posteriori (MAP) reconstruction algorithm. In this contribution, we use the PET-SORTEO Monte Carlo simulator to evaluate the quantitative accuracy reached by three different anatomical priors when reconstructing positron emission tomography (PET) brain images, using volumetric magnetic resonance imaging (MRI) to provide the anatomical information. The priors are: 1) a prior especially developed for FDG PET brain imaging, which relies on a segmentation of the MR-image (Baete , 2004); 2) the joint entropy-prior (Nuyts, 2007); 3) a prior that encourages smoothness within a position dependent neighborhood, computed from the MR-image. The latter prior was recently proposed by our group in (Vunckx and Nuyts, 2010), and was based on the prior presented by Bowsher (2004). The two latter priors do not rely on an explicit segmentation, which makes them more generally applicable than a segmentation-based prior. All three priors produced a compromise between noise and bias that was clearly better than that obtained with postsmoothed maximum likelihood expectation maximization (MLEM) or MAP with a relative difference prior. The performance of the joint entropy prior was slightly worse than that of the other two priors. The performance of the segmentation-based prior is quite sensitive to the accuracy of the segmentation. In contrast to the joint entropy-prior, the Bowsher-prior is easily tuned and does not suffer from convergence problems. PMID:22049363

  9. Development of fluoroscopic registration in spinal neuronavigation

    NASA Astrophysics Data System (ADS)

    Abbasi, Hamid R.; Grzeszczuk, Robert; Chin, Shao; Holz, H.; Hariri, Sanaz; Badr, Rana; Kim, Daniel; Adler, John R.; Shahidi, Ramin

    2001-05-01

    We present a system involving a computer-instrumented fluoroscope for the purpose of 3D navigation and guidance using pre-operative diagnostic scans as a reference. The goal of the project is to devise a computer-assisted tool that will improve the accuracy, reduce risk, minimize the invasiveness, and shorten the time it takes to perform a variety of neurosurgical and orthopedic procedures of the spine. For this purpose we propose an apparatus that will track surgical tools and localize them with respect to the patient's 3D anatomy and pre-operative 3D diagnostic scans using intraoperative fluoroscopy for in situ registration and localization of embedded fiducials. Preliminary studies have found a fiducial registration error (FRE) of 1.41 mm and a Target Localization Error (TLE) of 0.48 mm. The resulting system leverages equipment already commonly available in the operating room (OR), providing an important new functionality that is free of many current limitations, such as the inadequacy of skin fiducials for spinal neuronavigation, while keeping costs contained.

  10. 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. PMID:23980505

  11. Focused Ultrasound Simultaneous Irradiation/MRI Imaging, and Two-Stage General Kinetic Model

    PubMed Central

    Huang, Sheng-Yao; Ko, Chia-En; Chen, Gin-Shin; Chung, I-Fang; Yang, Feng-Yi

    2014-01-01

    Many studies have investigated how to use focused ultrasound (FUS) to temporarily disrupt the blood-brain barrier (BBB) in order to facilitate the delivery of medication into lesion sites in the brain. In this study, through the setup of a real-time system, FUS irradiation and injections of ultrasound contrast agent (UCA) and Gadodiamide (Gd, an MRI contrast agent) can be conducted simultaneously during MRI scanning. By using this real-time system, we were able to investigate in detail how the general kinetic model (GKM) is used to estimate Gd penetration in the FUS irradiated area in a rat's brain resulting from UCA concentration changes after single FUS irradiation. Two-stage GKM was proposed to estimate the Gd penetration in the FUS irradiated area in a rat's brain under experimental conditions with repeated FUS irradiation combined with different UCA concentrations. The results showed that the focal increase in the transfer rate constant of Ktrans caused by BBB disruption was dependent on the doses of UCA. Moreover, the amount of in vivo penetration of Evans blue in the FUS irradiated area in a rat's brain under various FUS irradiation experimental conditions was assessed to show the positive correlation with the transfer rate constants. Compared to the GKM method, the Two-stage GKM is more suitable for estimating the transfer rate constants of the brain treated with repeated FUS irradiations. This study demonstrated that the entire process of BBB disrupted by FUS could be quantitatively monitored by real-time dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). PMID:24949997

  12. Long-circulating PEGylated manganese ferrite nanoparticles for MRI-based molecular imaging.

    PubMed

    Pernia Leal, Manuel; Rivera-Fernández, Sara; Franco, Jaime M; Pozo, David; de la Fuente, Jesús M; García-Martín, María Luisa

    2015-02-01

    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. PMID:25554363

  13. Three-band MRI image fusion utilizing the wavelet-based method optimized with two quantitative fusion metrics

    NASA Astrophysics Data System (ADS)

    Zheng, Yufeng; Elmaghraby, Adel S.; Frigui, Hichem

    2006-03-01

    In magnetic resonance imaging (MRI), there are three bands of images ("MRI triplet") available, which are T1-, T2- and PD-weighted images. The three images of a MRI triplet provide complementary structure information and therefore it is useful for diagnosis and subsequent analysis to combine three-band images into one. We propose an advanced discrete wavelet transform (αDWT) for three-band MRI image fusion and the αDWT algorithm is further optimized utilizing two quantitative fusion metrics - the image quality index (IQI) and ratio spatial frequency error (rSFe). In the aDWT method, principle component analysis (PCA) and morphological processing are incorporated into a regular DWT fusion algorithm. Furthermore, the αDWT has two adjustable parameters - the level of DWT decomposition (L d) and the length of the selected wavelet (L w) that determinately affect the fusion result. The fused image quality can be quantitatively measured with the established metrics - IQI and rSFe. Varying the control parameters (L d and L w), an iterative fusion procedure can be implemented and running until an optimized fusion is achieved. We fused and analyzed several MRI triplets from the Visible Human Project ® female dataset. From the quantitative and qualitative evaluations of fused images, we found that (1) the αDWTi-IQI algorithm produces a smoothed image whereas the αDWTi-rSFe algorithm yields a sharpened image, (2) fused image "T1+T2" is the most informative one in comparison with other two-in-one fusions (PD+T1 and PD+T2), (3) for three-in-one fusions, no significant difference is observed among the three fusions of (PD+T1)+T2, (PD+T2)+T1 and (T1+T2)+PD, thus the order of fusion does not play an important role. The fused images can significantly benefit medical diagnosis and also the further image processing such as multi-modality image fusion (with CT images), visualization (colorization), segmentation, classification and computer-aided diagnosis (CAD).

  14. Golden-Angle Radial Sparse Parallel MRI: Combination of Compressed Sensing, Parallel Imaging, and Golden-Angle Radial Sampling for Fast and Flexible Dynamic Volumetric MRI

    PubMed Central

    Feng, Li; Grimm, Robert; Block, Kai Tobias; Chandarana, Hersh; Kim, Sungheon; Xu, Jian; Axel, Leon; Sodickson, Daniel K.; Otazo, Ricardo

    2013-01-01

    Purpose To develop a fast and flexible free-breathing dynamic volumetric MRI technique, iterative Golden-angle RAdial Sparse Parallel MRI (iGRASP), that combines compressed sensing, parallel imaging, and golden-angle radial sampling. Methods Radial k-space data are acquired continuously using the golden-angle scheme and sorted into time series by grouping an arbitrary number of consecutive spokes into temporal frames. An iterative reconstruction procedure is then performed on the undersampled time series where joint multicoil sparsity is enforced by applying a total-variation constraint along the temporal dimension. Required coil-sensitivity profiles are obtained from the time-averaged data. Results iGRASP achieved higher acceleration capability than either parallel imaging or coil-by-coil compressed sensing alone. It enabled dynamic volumetric imaging with high spatial and temporal resolution for various clinical applications, including free-breathing dynamic contrast-enhanced imaging in the abdomen of both adult and pediatric patients, and in the breast and neck of adult patients. Conclusion The high performance and flexibility provided by iGRASP can improve clinical studies that require robustness to motion and simultaneous high spatial and temporal resolution. PMID:24142845

  15. A Comparison of Hyperelastic Warping of PET Images with Tagged MRI for the Analysis of Cardiac Deformation

    DOE PAGESBeta

    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

  16. 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

  17. Fast imaging of laboratory core floods using 3D compressed sensing RARE MRI.

    PubMed

    Ramskill, N P; Bush, I; Sederman, A J; Mantle, M D; Benning, M; Anger, B C; Appel, M; Gladden, L F

    2016-09-01

    Three-dimensional (3D) imaging of the fluid distributions within the rock is essential to enable the unambiguous interpretation of core flooding data. Magnetic resonance imaging (MRI) has been widely used to image fluid saturation in rock cores; however, conventional acquisition strategies are typically too slow to capture the dynamic nature of the displacement processes that are of interest. Using Compressed Sensing (CS), it is possible to reconstruct a near-perfect image from significantly fewer measurements than was previously thought necessary, and this can result in a significant reduction in the image acquisition times. In the present study, a method using the Rapid Acquisition with Relaxation Enhancement (RARE) pulse sequence with CS to provide 3D images of the fluid saturation in rock core samples during laboratory core floods is demonstrated. An objective method using image quality metrics for the determination of the most suitable regularisation functional to be used in the CS reconstructions is reported. It is shown that for the present application, Total Variation outperforms the Haar and Daubechies3 wavelet families in terms of the agreement of their respective CS reconstructions with a fully-sampled reference image. Using the CS-RARE approach, 3D images of the fluid saturation in the rock core have been acquired in 16min. The CS-RARE technique has been applied to image the residual water saturation in the rock during a water-water displacement core flood. With a flow rate corresponding to an interstitial velocity of vi=1.89±0.03ftday(-1), 0.1 pore volumes were injected over the course of each image acquisition, a four-fold reduction when compared to a fully-sampled RARE acquisition. Finally, the 3D CS-RARE technique has been used to image the drainage of dodecane into the water-saturated rock in which the dynamics of the coalescence of discrete clusters of the non-wetting phase are clearly observed. The enhancement in the temporal resolution that has

  18. Fast imaging of laboratory core floods using 3D compressed sensing RARE MRI

    NASA Astrophysics Data System (ADS)

    Ramskill, N. P.; Bush, I.; Sederman, A. J.; Mantle, M. D.; Benning, M.; Anger, B. C.; Appel, M.; Gladden, L. F.

    2016-09-01

    Three-dimensional (3D) imaging of the fluid distributions within the rock is essential to enable the unambiguous interpretation of core flooding data. Magnetic resonance imaging (MRI) has been widely used to image fluid saturation in rock cores; however, conventional acquisition strategies are typically too slow to capture the dynamic nature of the displacement processes that are of interest. Using Compressed Sensing (CS), it is possible to reconstruct a near-perfect image from significantly fewer measurements than was previously thought necessary, and this can result in a significant reduction in the image acquisition times. In the present study, a method using the Rapid Acquisition with Relaxation Enhancement (RARE) pulse sequence with CS to provide 3D images of the fluid saturation in rock core samples during laboratory core floods is demonstrated. An objective method using image quality metrics for the determination of the most suitable regularisation functional to be used in the CS reconstructions is reported. It is shown that for the present application, Total Variation outperforms the Haar and Daubechies3 wavelet families in terms of the agreement of their respective CS reconstructions with a fully-sampled reference image. Using the CS-RARE approach, 3D images of the fluid saturation in the rock core have been acquired in 16 min. The CS-RARE technique has been applied to image the residual water saturation in the rock during a water-water displacement core flood. With a flow rate corresponding to an interstitial velocity of vi = 1.89 ± 0.03 ft day-1, 0.1 pore volumes were injected over the course of each image acquisition, a four-fold reduction when compared to a fully-sampled RARE acquisition. Finally, the 3D CS-RARE technique has been used to image the drainage of dodecane into the water-saturated rock in which the dynamics of the coalescence of discrete clusters of the non-wetting phase are clearly observed. The enhancement in the temporal resolution

  19. Minimizing dose during fluoroscopic tracking through geometric performance feedback

    PubMed Central

    Siddique, S.; Fiume, E.; Jaffray, D. A.

    2011-01-01

    Purpose: There is a growing concern regarding the dose delivered during x-ray fluoroscopy guided procedures, particularly in interventional cardiology and neuroradiology, and in real-time tumor tracking radiotherapy and radiosurgery. Many of these procedures involve long treatment times, and as such, there is cause for concern regarding the dose delivered and the associated radiation related risks. An insufficient dose, however, may convey less geometric information, which may lead to inaccuracy and imprecision in intervention placement. The purpose of this study is to investigate a method for achieving the required tracking uncertainty for a given interventional procedure using minimal dose.Methods: A simple model is used to demonstrate that a relationship exists between imaging dose and tracking uncertainty. A feedback framework is introduced that exploits this relationship to modulate the tube current (and hence the dose) in order to maintain the required uncertainty for a given interventional procedure. This framework is evaluated in the context of a fiducial tracking problem associated with image-guided radiotherapy in the lung. A particle filter algorithm is used to robustly track the fiducial as it traverses through regions of high and low quantum noise. Published motion models are incorporated in a tracking test suite to evaluate the dose-localization performance trade-offs.Results: It is shown that using this framework, the entrance surface exposure can be reduced by up to 28.6% when feedback is employed to operate at a geometric tracking uncertainty of 0.3 mm.Conclusions: The analysis reveals a potentially powerful technique for dynamic optimization of fluoroscopic imaging parameters to control the applied dose by exploiting the trade-off between tracking uncertainty and x-ray exposure per frame. PMID:21776784

  20. 3D MRI brain image segmentation based on region restricted EM algorithm

    NASA Astrophysics Data System (ADS)

    Li, Zhong; Fan, Jianping

    2008-03-01

    This paper presents a novel algorithm of 3D human brain tissue segmentation and classification in magnetic resonance image (MRI) based on region restricted EM algorithm (RREM). The RREM is a level set segmentation method while the evolution of the contours was driven by the force field composed by the probability density functions of the Gaussian models. Each tissue is modeled by one or more Gaussian models restricted by free shaped contour so that the Gaussian models are adaptive to the local intensities. The RREM is guaranteed to be convergency and achieving the local minimum. The segmentation avoids to be trapped in the local minimum by the split and merge operation. A fuzzy rule based classifier finally groups the regions belonging to the same tissue and forms the segmented 3D image of white matter (WM) and gray matter (GM) which are of major interest in numerous applications. The presented method can be extended to segment brain images with tumor or the images having part of the brain removed with the adjusted classifier.

  1. Imaging corticospinal tract connectivity in injured rat spinal cord using manganese-enhanced MRI

    PubMed Central

    Bilgen, Mehmet

    2006-01-01

    Background Manganese-enhanced MRI (MEI) offers a novel neuroimaging modality to trace corticospinal tract (CST) in live animals. This paper expands this capability further and tests the utility of MEI to image axonal fiber connectivity in CST of injured spinal cord (SC). Methods A rat was injured at the thoracic T4 level of the SC. The CST was labeled with manganese (Mn) injected intracortically at two weeks post injury. Next day, the injured SC was imaged using MEI and diffusion tensor imaging (DTI) modalities. Results In vivo MEI data obtained from cervical SC confirmed that CST was successfully labeled with Mn. Ex vivo MEI data obtained from excised SC depicted Mn labeling of the CST in SC sections caudal to the lesion, which meant that Mn was transported through the injury, possibly mediated by viable CST fibers present at the injury site. Examining the ex vivo data from the injury epicenter closely revealed a thin strip of signal enhancement located ventrally between the dorsal horns. This enhancement was presumably associated with the Mn accumulation in these intact fibers projecting caudally as part of the CST. Additional measurements with DTI supported this view. Conclusion Combining these preliminary results collectively demonstrated the feasibility of imaging fiber connectivity in experimentally injured SC using MEI. This approach may play important role in future investigations aimed at understanding the neuroplasticity in experimental SCI research. PMID:17112375

  2. 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.

  3. 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.

  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. Occipital sulci patterns in patients with schizophrenia and migraine headache using magnetic resonance imaging (MRI).

    PubMed

    Sulejmanpašić, Gorana; Suljić, Enra; Šabanagić-Hajrić, Selma

    2016-08-01

    Aim To examine the presence of morphologic variations of occipital sulci patternsin patients with schizophrenia and migraine headacheregarding gender and laterality using magnetic resonance imaging (MRI). Methods This study included 80 patients and brain scans were performed to analyze interhemispheric symmetry and the sulcal patterns of the occipital region of both hemispheres. Average total volumes of both hemispheres of the healthy population were used for comparison. Results There was statistically significant difference between subjects considering gender (p=0.012)with no difference regarding age(p=0.1821). Parameters of parieto-occipital fissure (p=0.0314), body of the calcarine sulcus (p=0.0213), inferior sagittal sulcus (p=0.0443), and lateral occipital sulcus (p=0.0411) showed statistically significant difference only of left hemisphere in male patients with schizophrenia with shallowerdepth of the sulcus. Conclusion Representation of neuroanatomical structures suggests the existence of structural neuroanatomic disorders with focal brain changes. Comparative analysis of occipital lobe and their morphologic structures (cortical dysmorphology) in patients with schizophreniausing MRI, according to genderindicates a significant cortical reduction in the left hemisphere only in the group of male patients compared to female patients and the control group. PMID:27313112

  6. Discriminative analysis of schizophrenia using support vector machine and recursive feature elimination on structural MRI images.

    PubMed

    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

    2016-07-01

    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

  7. Imaging as a biomarker in drug discovery for Alzheimer’s disease: is MRI a suitable technology?

    PubMed Central

    2014-01-01

    This review provides perspectives on the utility of magnetic resonance imaging (MRI) as a neuroimaging approach in the development of novel treatments for Alzheimer’s disease. These considerations were generated in a roundtable at a recent Wellcome Trust meeting that included experts from academia and industry. It was agreed that MRI, either structural or functional, could be used as a diagnostic, for assessing worsening of disease status, for monitoring vascular pathology, and for stratifying clinical trial populations. It was agreed also that MRI implementation is in its infancy, requiring more evidence of association with the disease states, test-retest data, better standardization across multiple clinical sites, and application in multimodal approaches which include other imaging technologies, such as positron emission tomography, electroencephalography, and magnetoencephalography. PMID:25484927

  8. A practical MRI grading system for cervical foraminal stenosis based on oblique sagittal images

    PubMed Central

    Park, H-J; Kim, S S; Lee, S-Y; Chung, E-C; Rho, M-H; Kwon, H-J; Kook, S-H

    2013-01-01

    Objective: To propose a new and practical MRI grading method for cervical neural foraminal stenosis and to evaluate its reproducibility. Methods: We evaluated 50 patients (37 males and 13 females, mean age 49 years) who visited our institution and underwent oblique sagittal MRI of the cervical spine. A total of 300 foramina and corresponding nerve roots in 50 patients were qualitatively analysed from C4–5 to C6–7. We assessed the grade of cervical foraminal stenosis at the maximal narrowing point according to the new grading system based on T2 weighted oblique sagittal images. The incidence of each of the neural foraminal stenosis grades according to the cervical level was analysed by χ2 tests. Intra- and interobserver agreements between two radiologists were analysed using kappa statistics. Kappa value interpretations were poor (κ<0.1), slight (0.1≤κ≤0.2), fair (0.2<κ≤0.4), moderate (0.4<κ≤0.6), substantial (0.6<κ≤0.8) and almost perfect (0.8<κ≤1.0). Results: Significant stenoses (Grades 2 and 3) were rarely found at the C4–5 level. The incidence of Grade 3 at the C5–6 level was higher than that at other levels, a difference that was statistically significant. The overall intra-observer agreement according to the cervical level was almost perfect. The agreement at each level was almost perfect, except for only substantial agreement at the right C6–7 by Reader 2. No statistically significant differences were seen according to the cervical level. Overall kappa values of interobserver agreement according to the cervical level were almost perfect. In addition, the agreement of each level was almost perfect. Overall intra- and interobserver agreement for the presence of foraminal stenosis (Grade 0 vs Grades 1, 2 and 3) and for significant stenosis (Grades 0 and 1 vs Grades 2 and 3) showed similar results and were almost perfect. However, only substantial agreement was seen in the right C6–7. Conclusion: A new grading system for cervical

  9. Noninvasive functional cardiac electrical source imaging: combining MRI and ECG mapping for imaging electrical function

    NASA Astrophysics Data System (ADS)

    Tilg, Bernhard; Modre, Robert; Fischer, Gerald; Hanser, Friedrich; Messnarz, Bernd; Schocke, Michael F. H.; Kremser, Christian; Roithinger, Franz

    2002-04-01

    Inverse electrocardiography has been developing for several years. By coupling electrocardiographic mapping and 3D+time anatomical data, the electrical excitation sequence can be imaged completely noninvasively in the human heart. In this study, a bidomain theory based surface heart model activation time imaging approach was applied to single beat data of atrial and ventricular depolarization. For sinus and paced rhythms, the sites of early activation and the areas with late activation were estimated with sufficient accuracy. In particular for focal arrhythmias, this model-based imaging approach might allow the guidance and evaluation of antiarrhythmic interventions, for instance, in case of catheter ablation or drug therapy.

  10. 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

  11. 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

  12. 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.

  13. 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

  14. 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

  15. Probing different perfluorocarbons for in vivo inflammation imaging by 19F MRI: image reconstruction, biological half-lives and sensitivity.

    PubMed

    Jacoby, Christoph; Temme, Sebastian; Mayenfels, Friederike; Benoit, Nicole; Krafft, Marie Pierre; Schubert, Rolf; Schrader, Jürgen; Flögel, Ulrich

    2014-03-01

    Inflammatory processes can reliably be assessed by (19)F MRI using perfluorocarbons (PFCs), which is primarily based on the efficient uptake of emulsified PFCs by circulating cells of the monocyte-macrophage system and subsequent infiltration of the (19)F-labeled cells into affected tissue. An ideal candidate for the sensitive detection of fluorine-loaded cells is the biochemically inert perfluoro-15-crown-5 ether (PFCE), as it contains 20 magnetically equivalent (19)F atoms. However, the biological half-life of PFCE in the liver and spleen is extremely long, and so this substance is not suitable for future clinical applications. In the present study, we investigated alternative, nontoxic PFCs with predicted short biological half-lives and high fluorine content: perfluorooctyl bromide (PFOB), perfluorodecalin (PFD) and trans-bis-perfluorobutyl ethylene (F-44E). Despite the complex spectra of these compounds, we obtained artifact-free images using sine-squared acquisition-weighted three-dimensional chemical shift imaging and dedicated reconstruction accomplished with in-house-developed software. The signal-to-noise ratio of the images was maximized using a Nutall window with only moderate localization error. Using this approach, the retention times of the different PFCs in murine liver and spleen were determined at 9.4 T. The biological half-lives were estimated to be 9 days (PFD), 12 days (PFOB) and 28 days (F-44E), compared with more than 250 days for PFCE. In vivo sensitivity for inflammation imaging was assessed using an ear clip injury model. The alternative PFCs PFOB and F-44E provided 37% and 43%, respectively, of the PFCE intensities, whereas PFD did not show any signal in the ear model. Thus, for in vivo monitoring of inflammatory processes, PFOB emerges as the most promising candidate for possible future translation of (19)F MR inflammation imaging to human applications. PMID:24353148

  16. 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.

  17. 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.

  18. A method for quantitative analysis of regional lung ventilation using deformable image registration of CT and hybrid hyperpolarized gas/1H MRI.

    PubMed

    Tahir, Bilal A; Swift, Andrew J; Marshall, Helen; Parra-Robles, Juan; Hatton, Matthew Q; Hartley, Ruth; Kay, Richard; Brightling, Christopher E; Vos, Wim; Wild, Jim M; Ireland, Rob H

    2014-12-01

    Hyperpolarized gas magnetic resonance imaging (MRI) generates highly detailed maps of lung ventilation and physiological function while CT provides corresponding anatomical and structural information. Fusion of such complementary images enables quantitative analysis of pulmonary structure-function. However, direct image registration of hyperpolarized gas MRI to CT is problematic, particularly in lungs whose boundaries are difficult to delineate due to ventilation heterogeneity. This study presents a novel indirect method of registering hyperpolarized gas MRI to CT utilizing (1)H-structural MR images that are acquired in the same breath-hold as the gas MRI. The feasibility of using this technique for regional quantification of ventilation of specific pulmonary structures is demonstrated for the lobes.The direct and indirect methods of hyperpolarized gas MRI to CT image registration were compared using lung images from 15 asthma patients. Both affine and diffeomorphic image transformations were implemented. Registration accuracy was evaluated using the target registration error (TRE) of anatomical landmarks identified on (1)H MRI and CT. The Wilcoxon signed-rank test was used to test statistical significance.For the affine transformation, the indirect method of image registration was significantly more accurate than the direct method (TRE = 14.7 ± 3.2 versus 19.6 ± 12.7 mm, p = 0.036). Using a deformable transformation, the indirect method was also more accurate than the direct method (TRE = 13.5 ± 3.3 versus 20.4 ± 12.8 mm, p = 0.006).Accurate image registration is critical for quantification of regional lung ventilation with hyperpolarized gas MRI within the anatomy delineated by CT. Automatic deformable image registration of hyperpolarized gas MRI to CT via same breath-hold (1)H MRI is more accurate than direct registration. Potential applications include improved multi-modality image fusion, functionally weighted radiotherapy planning, and quantification of

  19. Development of the Deep Impact Ejecta Based on Early MRI Images

    NASA Astrophysics Data System (ADS)

    Nagdimunov, Lev; Ludmilla, Kolokolova; Wolff, Michael; A'Hearn, Michael F.; Farnham, Tony

    2014-11-01

    We analyze a sequence of the images acquired by the Deep Impact spacecraft High Resolution (HRI) and Medium Resolution (MRI) instruments during the first seconds after impact. These early images reflect the development of material excavation from the cometary nucleus, enabling a study of variations in the excavated material with time, and potentially allowing a peek into the nucleus’ interior. Simply studying the brightness of the ejecta plume and its distribution as a function of height and time-after-impact could provide some insight into the characteristics of the ejecta. However, including the optical thickness of the ejecta offers an additional source of information through the resultant shadow on the surface of the nucleus, and brightness variations within it. Our goal was to reproduce both the distribution of brightness in the plume and in its shadow, thus constraining the characteristics of the ejecta. To achieve this, we used a 3D radiative transfer package HYPERION (http://hyperion-rt.org). The parameters of our dust modeling were composition, size distribution, and number density of particles at the base of the ejecta cone. Composition was created as a mixture of silicates, carbon and organics, ice, as well as voids to account for particle porosity. In our current modeling, we use the results of a parameter survey of dust characteristics reported previously, which was targeted to primarily simulating an HRI image taken at around 1 sec. In this survey, the best fit to Deep Impact data and excavated mass constraints showed a dust/ice mass ratio ≥ 1, with some individual particle porosity necessary to retrieve a good fit (we checked individual particle density extremes of 0.4 g/cm3 and 1.75 g/cm3). Our current work explores the spatial distribution of dust within the ejecta plume and focuses on the changes in dust characteristics over time by analyzing and simulating a sequence of Medium Resolution (MRI) images, attempting to reveal the structure of the

  20. 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

  1. 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.

  2. Frontiers for the Early Diagnosis of AD by Means of MRI Brain Imaging and Support Vector Machines.

    PubMed

    Salvatore, Christian; Battista, Petronilla; Castiglioni, Isabella

    2016-01-01

    The emergence of Alzheimer's Disease (AD) as a consequence of increasing aging population makes urgent the availability of methods for the early and accurate diagnosis. Magnetic Resonance Imaging (MRI) could be used as in vivo, non invasive tool to identify sensitive and specific markers of very early AD progression. In recent years, multivariate pattern analysis (MVPA) and machine- learning algorithms have attracted strong interest within the neuroimaging community, as they allow automatic classification of imaging data with higher performance than univariate statistical analysis. An exhaustive search of PubMed, Web of Science and Medline records was performed in this work, in order to retrieve studies focused on the potential role of MRI in aiding the clinician in early diagnosis of AD by using Support Vector Machines (SVMs) as MVPA automated classification method. A total of 30 studies emerged, published from 2008 to date. This review aims to give a state-of-the-art overview about SVM for the early and differential diagnosis of AD-related pathologies by means of MRI data, starting from preliminary steps such as image pre-processing, feature extraction and feature selection, and ending with classification, validation strategies and extraction of MRI-related biomarkers. The main advantages and drawbacks of the different techniques were explored. Results obtained by the reviewed studies were reported in terms of classification performance and biomarker outcomes, in order to shed light on the parameters that accompany normal and pathological aging. Unresolved issues and possible future directions were finally pointed out. PMID:26567735

  3. 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

  4. Upper gastrointestinal fluoroscopic simulator for neonates with bilious emesis.

    PubMed

    Benya, Ellen C; Wyers, Mary R; O'Brien, Ellen K; Nandhan, Vikram; Adler, Mark D

    2015-08-01

    Prompt diagnosis of malrotation and midgut volvulus in infants with bilious emesis is critical. However because of the limited frequency of pediatric upper gastrointestinal (UGI) fluoroscopic procedures in neonates, many diagnostic radiology residents complete their training never having seen or performed a UGI on a baby for evaluation of malrotation and midgut volvulus. A UGI simulation model for infants with bilious emesis was created to supplement the hands-on fluoroscopic experience of residents in training. We are now studying the addition of simulated UGI studies to our pediatric radiology curriculum. PMID:25796384

  5. 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