WorldWideScience

Sample records for diffusion mri processing

  1. Mathematical methods for diffusion MRI processing

    International Nuclear Information System (INIS)

    Lenglet, C.; Lenglet, C.; Sapiro, G.; Campbell, J.S.W.; Pike, G.B.; Campbell, J.S.W.; Siddiqi, K.; Descoteaux, M.; Haro, G.; Wassermann, D.; Deriche, R.; Wassermann, D.; Anwander, A.; Thompson, P.M.

    2009-01-01

    In this article, we review recent mathematical models and computational methods for the processing of diffusion Magnetic Resonance Images, including state-of-the-art reconstruction of diffusion models, cerebral white matter connectivity analysis, and segmentation techniques. We focus on Diffusion Tensor Images (DTI) and Q-Ball Images (QBI). (authors)

  2. A theoretical signal processing framework for linear diffusion MRI: Implications for parameter estimation and experiment design.

    Science.gov (United States)

    Varadarajan, Divya; Haldar, Justin P

    2017-11-01

    The data measured in diffusion MRI can be modeled as the Fourier transform of the Ensemble Average Propagator (EAP), a probability distribution that summarizes the molecular diffusion behavior of the spins within each voxel. This Fourier relationship is potentially advantageous because of the extensive theory that has been developed to characterize the sampling requirements, accuracy, and stability of linear Fourier reconstruction methods. However, existing diffusion MRI data sampling and signal estimation methods have largely been developed and tuned without the benefit of such theory, instead relying on approximations, intuition, and extensive empirical evaluation. This paper aims to address this discrepancy by introducing a novel theoretical signal processing framework for diffusion MRI. The new framework can be used to characterize arbitrary linear diffusion estimation methods with arbitrary q-space sampling, and can be used to theoretically evaluate and compare the accuracy, resolution, and noise-resilience of different data acquisition and parameter estimation techniques. The framework is based on the EAP, and makes very limited modeling assumptions. As a result, the approach can even provide new insight into the behavior of model-based linear diffusion estimation methods in contexts where the modeling assumptions are inaccurate. The practical usefulness of the proposed framework is illustrated using both simulated and real diffusion MRI data in applications such as choosing between different parameter estimation methods and choosing between different q-space sampling schemes. Copyright © 2017 Elsevier Inc. All rights reserved.

  3. Automated processing pipeline for neonatal diffusion MRI in the developing Human Connectome Project.

    Science.gov (United States)

    Bastiani, Matteo; Andersson, Jesper L R; Cordero-Grande, Lucilio; Murgasova, Maria; Hutter, Jana; Price, Anthony N; Makropoulos, Antonios; Fitzgibbon, Sean P; Hughes, Emer; Rueckert, Daniel; Victor, Suresh; Rutherford, Mary; Edwards, A David; Smith, Stephen M; Tournier, Jacques-Donald; Hajnal, Joseph V; Jbabdi, Saad; Sotiropoulos, Stamatios N

    2018-05-28

    The developing Human Connectome Project is set to create and make available to the scientific community a 4-dimensional map of functional and structural cerebral connectivity from 20 to 44 weeks post-menstrual age, to allow exploration of the genetic and environmental influences on brain development, and the relation between connectivity and neurocognitive function. A large set of multi-modal MRI data from fetuses and newborn infants is currently being acquired, along with genetic, clinical and developmental information. In this overview, we describe the neonatal diffusion MRI (dMRI) image processing pipeline and the structural connectivity aspect of the project. Neonatal dMRI data poses specific challenges, and standard analysis techniques used for adult data are not directly applicable. We have developed a processing pipeline that deals directly with neonatal-specific issues, such as severe motion and motion-related artefacts, small brain sizes, high brain water content and reduced anisotropy. This pipeline allows automated analysis of in-vivo dMRI data, probes tissue microstructure, reconstructs a number of major white matter tracts, and includes an automated quality control framework that identifies processing issues or inconsistencies. We here describe the pipeline and present an exemplar analysis of data from 140 infants imaged at 38-44 weeks post-menstrual age. Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.

  4. Computational Diffusion MRI : MICCAI Workshop

    CERN Document Server

    Grussu, Francesco; Ning, Lipeng; Tax, Chantal; Veraart, Jelle

    2018-01-01

    This volume presents the latest developments in the highly active and rapidly growing field of diffusion MRI. The reader will find numerous contributions covering a broad range of topics, from the mathematical foundations of the diffusion process and signal generation, to new computational methods and estimation techniques for the in-vivo recovery of microstructural and connectivity features, as well as frontline applications in neuroscience research and clinical practice. These proceedings contain the papers presented at the 2017 MICCAI Workshop on Computational Diffusion MRI (CDMRI’17) held in Québec, Canada on September 10, 2017, sharing new perspectives on the most recent research challenges for those currently working in the field, but also offering a valuable starting point for anyone interested in learning computational techniques in diffusion MRI. This book includes rigorous mathematical derivations, a large number of rich, full-colour visualisations and clinically relevant results. As such, it wil...

  5. Evaluating contextual processing in diffusion MRI: application to optic radiation reconstruction for epilepsy surgery.

    Directory of Open Access Journals (Sweden)

    Chantal M W Tax

    Full Text Available Diffusion MRI and tractography allow for investigation of the architectural configuration of white matter in vivo, offering new avenues for applications like presurgical planning. Despite the promising outlook, there are many pitfalls that complicate its use for (clinical application. Amongst these are inaccuracies in the geometry of the diffusion profiles on which tractography is based, and poor alignment with neighboring profiles. Recently developed contextual processing techniques, including enhancement and well-posed geometric sharpening, have shown to result in sharper and better aligned diffusion profiles. However, the research that has been conducted up to now is mainly of theoretical nature, and so far these techniques have only been evaluated by visual inspection of the diffusion profiles. In this work, the method is evaluated in a clinically relevant application: the reconstruction of the optic radiation for epilepsy surgery. For this evaluation we have developed a framework in which we incorporate a novel scoring procedure for individual pathways. We demonstrate that, using enhancement and sharpening, the extraction of an anatomically plausible reconstruction of the optic radiation from a large amount of probabilistic pathways is greatly improved in three healthy controls, where currently used methods fail to do so. Furthermore, challenging reconstructions of the optic radiation in three epilepsy surgery candidates with extensive brain lesions demonstrate that it is beneficial to integrate these methods in surgical planning.

  6. Diffusion, confusion and functional MRI

    International Nuclear Information System (INIS)

    Le Bihan, Denis

    2012-01-01

    Diffusion MRI has been introduced in 1985 and has had a very successful life on its own. While it has become a standard for imaging stroke and white matter disorders, the borders between diffusion MRI and the general field of fMRI have always remained fuzzy. First, diffusion MRI has been used to obtain images of brain function, based on the idea that diffusion MRI could also be made sensitive to blood flow, through the intra-voxel incoherent motion (IVIM) concept. Second, the IVIM concept helped better understand the contribution from different vasculature components to the BOLD fMRI signal. Third, it has been shown recently that a genuine fMRI signal can be obtained with diffusion MRI. This 'DfMRI' signal is notably different from the BOLD fMRI signal, especially for its much faster response to brain activation both at onset and offset, which points out to structural changes in the neural tissues, perhaps such as cell swelling, occurring in activated neural tissue. This short article reviews the major steps which have paved the way for this exciting development, underlying how technical progress with MRI equipment has each time been instrumental to expand the horizon of diffusion MRI toward the field of fMRI. (authors)

  7. 2015 MICCAI Workshop on Computational Diffusion MRI

    CERN Document Server

    Ghosh, Aurobrata; Kaden, Enrico; Rathi, Yogesh; Reisert, Marco

    2016-01-01

    These Proceedings of the 2015 MICCAI Workshop “Computational Diffusion MRI” offer a snapshot of the current state of the art on a broad range of topics within the highly active and growing field of diffusion MRI. The topics vary from fundamental theoretical work on mathematical modeling, to the development and evaluation of robust algorithms, new computational methods applied to diffusion magnetic resonance imaging data, and applications in neuroscientific studies and clinical practice. Over the last decade interest in diffusion MRI has exploded. The technique provides unique insights into the microstructure of living tissue and enables in-vivo connectivity mapping of the brain. Computational techniques are key to the continued success and development of diffusion MRI and to its widespread transfer into clinical practice. New processing methods are essential for addressing issues at each stage of the diffusion MRI pipeline: acquisition, reconstruction, modeling and model fitting, image processing, fiber t...

  8. Diffusion MRI processing for multi-compartment characterization of brain pathology

    International Nuclear Information System (INIS)

    Hedouin, Renaud

    2017-01-01

    Diffusion weighted imaging (DWI) is a specific type of MRI acquisition based on the direction of diffusion of the brain water molecules. It allows, through several acquisitions, to model the brain microstructure, as white matter, which is significantly smaller than the voxel-resolution. To acquire a large number of images in a clinical setting, very-fast acquisition techniques are required as single-shot imaging. However these acquisitions suffer locally large distortions. We propose a block-matching registration method based on the acquisition of images with opposite phase-encoding directions (PED). This technique specially designed for Echo-Planar Images (EPI) robustly correct images and provides a deformation field. This field is applicable to an entire DWI series from only one reversed EPI allowing distortion correction with a minimal acquisition time cost. This registration algorithm has been validated both on phantom and on in vivo data and is available in our source medical image processing toolbox Anima. From these diffusion images, we are able to construct multi-compartments models (MCM) which can represent complex brain microstructure. Doing registration, averaging and atlas creation on these MCM images is required to perform studies and statistic analyses. We propose a general method to interpolate MCM as a simplification problem based on spectral clustering. This technique, which is adaptable for any MCM, has been validated on both synthetic and real data. Then, from a registered dataset, we performed a patient to population analysis at a voxel-level computing statistics on MCM parameters. Specifically designed tractography can also be used to make analysis, following tracks, based on individual anisotropic compartments. All these tools are designed and used on real data and contribute to the search of bio-markers for brain diseases such as multiple sclerosis. (author)

  9. Diffusion MRI of the neonate brain: acquisition, processing and analysis techniques

    Energy Technology Data Exchange (ETDEWEB)

    Pannek, Kerstin [University of Queensland, Centre for Clinical Research, Brisbane (Australia); University of Queensland, School of Medicine, Brisbane (Australia); University of Queensland, Centre for Advanced Imaging, Brisbane (Australia); Guzzetta, Andrea [IRCCS Stella Maris, Department of Developmental Neuroscience, Calambrone Pisa (Italy); Colditz, Paul B. [University of Queensland, Centre for Clinical Research, Brisbane (Australia); University of Queensland, Perinatal Research Centre, Brisbane (Australia); Rose, Stephen E. [University of Queensland, Centre for Clinical Research, Brisbane (Australia); University of Queensland, Centre for Advanced Imaging, Brisbane (Australia); University of Queensland Centre for Clinical Research, Royal Brisbane and Women' s Hospital, Brisbane (Australia)

    2012-10-15

    Diffusion MRI (dMRI) is a popular noninvasive imaging modality for the investigation of the neonate brain. It enables the assessment of white matter integrity, and is particularly suited for studying white matter maturation in the preterm and term neonate brain. Diffusion tractography allows the delineation of white matter pathways and assessment of connectivity in vivo. In this review, we address the challenges of performing and analysing neonate dMRI. Of particular importance in dMRI analysis is adequate data preprocessing to reduce image distortions inherent to the acquisition technique, as well as artefacts caused by head movement. We present a summary of techniques that should be used in the preprocessing of neonate dMRI data, and demonstrate the effect of these important correction steps. Furthermore, we give an overview of available analysis techniques, ranging from voxel-based analysis of anisotropy metrics including tract-based spatial statistics (TBSS) to recently developed methods of statistical analysis addressing issues of resolving complex white matter architecture. We highlight the importance of resolving crossing fibres for tractography and outline several tractography-based techniques, including connectivity-based segmentation, the connectome and tractography mapping. These techniques provide powerful tools for the investigation of brain development and maturation. (orig.)

  10. Less Confusion in Diffusion MRI

    NARCIS (Netherlands)

    Tax, CMW

    2016-01-01

    With its unique ability to investigate tissue architecture and microstructure in vivo, diffusion MRI (dMRI) has gained tremendous interest and the society has been continuously triggered to develop novel dMRI image analysis approaches. With the overwhelming amount of strategies currently available

  11. Diffusion MRI findings in phenylketonuria

    Energy Technology Data Exchange (ETDEWEB)

    Sener, R.N. [Dept. of Radiology, Ege Univ. Hospital, Izmir (Turkey)

    2003-12-01

    Two patients with phenylketonuria were studied who were under dietary control since infancy, and who were mentally normal. Diffusion MRI was obtained using a spin-echo, echo-planar sequence with a gradient strength of 30 mT/m at 1.5 T. A trace sequence (TR=5700 ms, and TE=139 ms) was used, acquired in 22 s. Heavily diffusion-weighted (b=1000 mm{sup 2}/s) images, and the apparent diffusion coefficient (ADC) values from automatically generated ADC maps were studied. There were two different patterns in these two patients, restricted and increased diffusion patterns. Restricted diffusion pattern consisted of high-signal on b=1000 s/mm{sup 2} images with low ADC values ranging from 0.46 to 0.57 x 10{sup -3} mm{sup 2}/s. Increased diffusion pattern consisted of normal b=1000 s/mm{sup 2} images with high ADC values ranging from 1.37 to 1.63 x 10{sup -3} mm{sup 2}/s. It is likely that these values reflected presence of two different histopathological changes in phenylketonuria or reflected different stages of the same disease. (orig.)

  12. Diffusion MRI findings in phenylketonuria

    International Nuclear Information System (INIS)

    Sener, R.N.

    2003-01-01

    Two patients with phenylketonuria were studied who were under dietary control since infancy, and who were mentally normal. Diffusion MRI was obtained using a spin-echo, echo-planar sequence with a gradient strength of 30 mT/m at 1.5 T. A trace sequence (TR=5700 ms, and TE=139 ms) was used, acquired in 22 s. Heavily diffusion-weighted (b=1000 mm 2 /s) images, and the apparent diffusion coefficient (ADC) values from automatically generated ADC maps were studied. There were two different patterns in these two patients, restricted and increased diffusion patterns. Restricted diffusion pattern consisted of high-signal on b=1000 s/mm 2 images with low ADC values ranging from 0.46 to 0.57 x 10 -3 mm 2 /s. Increased diffusion pattern consisted of normal b=1000 s/mm 2 images with high ADC values ranging from 1.37 to 1.63 x 10 -3 mm 2 /s. It is likely that these values reflected presence of two different histopathological changes in phenylketonuria or reflected different stages of the same disease. (orig.)

  13. Diffusion tensor MRI: clinical applications

    International Nuclear Information System (INIS)

    Meli, Francisco; Romero, Carlos; Carpintiero, Silvina; Salvatico, Rosana; Lambre, Hector; Vila, Jose

    2005-01-01

    Purpose: To evaluate the usefulness of diffusion-tensor imaging (DTI) on different neurological diseases, and to know if this technique shows additional information than conventional Magnetic Resonance Imaging (MRI). Materials and method: Eight patients, with neurological diseases (five patients with brain tumors, one with multiple sclerosis (MS), one with variant Creutzfeldt-Jakob disease (vCJD) and the other with delayed CO intoxication were evaluated. A MR scanner of 1.5 T was used and conventional sequences and DTI with twenty-five directions were done. Quantitative maps were gotten, where the fractional anisotropy (FA) through regions of interest (ROIs) in specific anatomic area were quantified (i.e.: internal and external capsules, frontal and temporal bundles, corpus fibers). Results: In the patients with brain tumors, there was a decrease of FA on intra and peritumoral fibers. Some of them had a disruption in their pattern. In patients with MS and CO intoxication, partial interruption along white matter bundles was demonstrated. However, a 'mismatch' between the findings of FLAIR, Diffusion-weighted images (DWI) and DTI, in the case of CO intoxication, was seen. Conclusions: DTI gave more information compared to conventional sequences about ultrastructural brain tissue in almost all the diseases above mentioned. Therefore, there is a work in progress about DTI acquisition, to evaluate a new technique, called tractography. (author)

  14. Diffusion microscopist simulator - The development and application of a Monte Carlo simulation system for diffusion MRI

    International Nuclear Information System (INIS)

    Yeh, C.H.

    2011-09-01

    Diffusion magnetic resonance imaging (dMRI) has made a significant breakthrough in neurological disorders and brain research thanks to its exquisite sensitivity to tissue cyto-architecture. However, as the water diffusion process in neuronal tissues is a complex biophysical phenomena at molecular scale, it is difficult to infer tissue microscopic characteristics on a voxel scale from dMRI data. The major methodological contribution of this thesis is the development of an integrated and generic Monte Carlo simulation framework, 'Diffusion Microscopist Simulator' (DMS), which has the capacity to create 3D biological tissue models of various shapes and properties, as well as to synthesize dMRI data for a large variety of MRI methods, pulse sequence design and parameters. DMS aims at bridging the gap between the elementary diffusion processes occurring at a micrometric scale and the resulting diffusion signal measured at millimetric scale, providing better insights into the features observed in dMRI, as well as offering ground-truth information for optimization and validation of dMRI acquisition protocols for different applications. We have verified the performance and validity of DMS through various benchmark experiments, and applied to address particular research topics in dMRI. Based on DMS, there are two major application contributions in this thesis. First, we use DMS to investigate the impact of finite diffusion gradient pulse duration (delta) on fibre orientation estimation in dMRI. We propose that current practice of using long delta, which is enforced by the hardware limitation of clinical MRI scanners, is actually beneficial for mapping fibre orientations, even though it violates the underlying assumption made in q-space theory. Second, we employ DMS to investigate the feasibility of estimating axon radius using a clinical MRI system. The results suggest that the algorithm for mapping the direct microstructures is applicable to dMRI data acquired from

  15. Imaging brain microstructure with diffusion MRI

    DEFF Research Database (Denmark)

    Alexander, Daniel C; Dyrby, Tim B; Nilsson, Markus

    2018-01-01

    This article gives an overview of microstructure imaging of the brain with diffusion MRI and reviews the state of the art. The microstructure-imaging paradigm aims to estimate and map microscopic properties of tissue using a model that links these properties to the voxel scale MR signal. Imaging ...

  16. Quantifying Pathology in Diffusion Weighted MRI

    NARCIS (Netherlands)

    Caan, M.W.A.

    2010-01-01

    In this thesis algorithms are proposed for quantification of pathology in Diffusion Weighted Magnetic Resonance Imaging (DW-MRI) data. Functional evidence for brain diseases can be explained by specific structural loss in the white matter of the brain. That is, certain biomarkers may exist where the

  17. MRI: update on technology diffusion and acquisition.

    Science.gov (United States)

    Hoppszallern, S; Hughes, C; Zimmerman, R A

    1991-04-01

    Over the past three years, magnetic resonance imaging (MRI) has become accepted as a valuable diagnostic tool, and its applications continue to expand. During this time, the number of units installed in the United States doubled. By 1990 about 2,000 MRI units were in place in the United States and nearly 20 percent of the MRI-installed base was mobile, according to a research study conducted by the Hadley Hart Group (Chicago) and Drew Consultants, Inc. (Concord, MA). With the introduction of the prospective payment system, many hospitals were hesitant to spend limited capital on new technology, such as MRI. At the same time, freestanding diagnostic imaging centers were on the rise. Some hospitals and entrepreneurs who foresaw the potential of MRI in health care pioneered its use in the clinical setting. Hospitals began to examine new partnership arrangements and alternative forms of financing, so that they too could offer MRI services. By the end of 1988, the majority of hospitals offering MRI services did not own their own unit and about 40 percent of the hospitals offering MRI services were in a mobile configuration according to the Hadley Hart Group. While the technology has been diffused into 100-bed hospitals via mobile service vendors in some parts of the country, many medium-sized and large hospitals also have entered the MRI services market in this fashion. In the larger hospitals, the patient demand or need for the service often would justify acquisition of MRI, but the expense of the technology, and in many areas restrictive state health planning policies, modified purchase of MRI systems by hospitals. Mobile service vendors offered hospitals a way to startup MRI services in a limited fashion without a major capital expenditure and its associated risk. As hospitals gain experience with mobile MRI and achieve or exceed their early utilization projections, administrators are reevaluating the need to expand services to a full-time fixed site. Early fixed

  18. Dipy, a library for the analysis of diffusion MRI data.

    Science.gov (United States)

    Garyfallidis, Eleftherios; Brett, Matthew; Amirbekian, Bagrat; Rokem, Ariel; van der Walt, Stefan; Descoteaux, Maxime; Nimmo-Smith, Ian

    2014-01-01

    Diffusion Imaging in Python (Dipy) is a free and open source software project for the analysis of data from diffusion magnetic resonance imaging (dMRI) experiments. dMRI is an application of MRI that can be used to measure structural features of brain white matter. Many methods have been developed to use dMRI data to model the local configuration of white matter nerve fiber bundles and infer the trajectory of bundles connecting different parts of the brain. Dipy gathers implementations of many different methods in dMRI, including: diffusion signal pre-processing; reconstruction of diffusion distributions in individual voxels; fiber tractography and fiber track post-processing, analysis and visualization. Dipy aims to provide transparent implementations for all the different steps of dMRI analysis with a uniform programming interface. We have implemented classical signal reconstruction techniques, such as the diffusion tensor model and deterministic fiber tractography. In addition, cutting edge novel reconstruction techniques are implemented, such as constrained spherical deconvolution and diffusion spectrum imaging (DSI) with deconvolution, as well as methods for probabilistic tracking and original methods for tractography clustering. Many additional utility functions are provided to calculate various statistics, informative visualizations, as well as file-handling routines to assist in the development and use of novel techniques. In contrast to many other scientific software projects, Dipy is not being developed by a single research group. Rather, it is an open project that encourages contributions from any scientist/developer through GitHub and open discussions on the project mailing list. Consequently, Dipy today has an international team of contributors, spanning seven different academic institutions in five countries and three continents, which is still growing.

  19. Diffusion-weighted MRI of the prostate

    International Nuclear Information System (INIS)

    Mueller-Lisse, U.G.; Scherr, M.K.; Mueller-Lisse, U.L.; Zamecnik, P.; Schlemmer, H.P.W.

    2011-01-01

    Diffusion-weighted magnetic resonance imaging (DWI) can complement MRI of the prostate in the detection and localization of prostate cancer, particularly after previous negative biopsy. A total of 13 original reports and 2 reviews published in 2010 demonstrate that prostate cancer can be detected by DWI due to its increased cell density and decreased diffusiveness, either qualitatively in DWI images or quantitatively by means of the apparent diffusion coefficient (ADC). In the prostate, the ADC is influenced by the strength of diffusion weighting, localization (peripheral or transitional zone), presence of prostatitis or hemorrhage and density and differentiation of prostate cancer cells. Mean differences between healthy tissue of the peripheral zone and prostate cancer appear to be smaller for ADC than for the (choline + creatine)/citrate ratio in MR spectroscopy. Test quality parameters vary greatly between different studies but appear to be slightly better for combined MRI and DWI than for MRI of the prostate alone. Clinical validation of DWI of the prostate requires both increased technical conformity and increased numbers of patients in clinical studies. (orig.) [de

  20. Analysis and visualization methods for interpretation of diffusion MRI data

    NARCIS (Netherlands)

    Vos, S.B.

    2013-01-01

    Diffusion MRI is an imaging technique that is very sensitive to microstructural changes in tissue. Diffusion tensor MRI, the most commonly used method, can estimate the magnitude and anisotropy of diffusion. These tensor-based diffusion parameters have been shown to change in many neuropathological

  1. Alterations in the inferior longitudinal fasciculus in autism and associations with visual processing: a diffusion-weighted MRI study.

    Science.gov (United States)

    Boets, Bart; Van Eylen, Lien; Sitek, Kevin; Moors, Pieter; Noens, Ilse; Steyaert, Jean; Sunaert, Stefan; Wagemans, Johan

    2018-01-01

    One of the most reported neural features of autism spectrum disorder (ASD) is the alteration of multiple long-range white matter fiber tracts, as assessed by diffusion-weighted imaging and indexed by reduced fractional anisotropy (FA). Recent methodological advances, however, have shown that this same pattern of reduced FA may be an artifact resulting from excessive head motion and poorer data quality and that aberrant structural connectivity in children with ASD is confined to the right inferior longitudinal fasciculus (ILF). This study aimed at replicating the observation of reduced FA along the right ILF in ASD, while controlling for group differences in head motion and data quality. In addition, we explored associations between reduced FA in the right ILF and quantitative ASD characteristics, and the involvement of the right ILF in visual processing, which is known to be altered in ASD. Global probabilistic tractography was performed on diffusion-weighted imaging data of 17 adolescent boys with ASD and 17 typically developing boys, matched for age, performance IQ, handedness, and data quality. Four tasks were administered to measure various aspects of visual information processing, together with questionnaires assessing ASD characteristics. Group differences were examined and the neural data were integrated with previously published findings using Bayesian statistics to quantify evidence for replication and to pool data and thus increase statistical power. (Partial) correlations were calculated to investigate associations between measures. The ASD group showed consistently reduced FA only in the right ILF and slower performance on the visual search task. Bayesian statistics pooling data across studies confirmed that group differences in FA were confined to the right ILF only, with the evidence for altered FA in the left ILF being indecisive. Lower FA in the right ILF tended to covary with slower visual search and a more fragmented part-oriented processing style

  2. Dipy, a library for the analysis of diffusion MRI data

    Directory of Open Access Journals (Sweden)

    Eleftherios eGaryfallidis

    2014-02-01

    Full Text Available Diffusion Imaging in Python (Dipy is a free and open source software projectfor the analysis of data from diffusion magnetic resonance imaging (dMRIexperiments. dMRI is an application of MRI that can be used to measurestructural features of brain white matter. Many methods have been developed touse dMRI data to model the local configuration of white matter nerve fiberbundles and infer the trajectory of bundles connecting different parts of thebrain.Dipy gathers implementations of many different methods in dMRI, including:diffusion signal pre-processing; reconstruction of diffusion distributions inindividual voxels; fiber tractography and fiber track post-processing, analysisand visualization. Dipy aims to provide transparent implementations forall the different steps of dMRI analysis with a uniform programming interface.We have implemented classical signal reconstruction techniques, such as thediffusion tensor model and deterministic fiber tractography. In addition,cutting edge novel reconstruction techniques are implemented, such asconstrained spherical deconvolution and diffusion spectrum imaging withdeconvolution, as well as methods for probabilistic tracking and originalmethods for tractography clustering. Many additional utility functions areprovided to calculate various statistics, informative visualizations, as wellas file-handling routines to assist in the development and use of noveltechniques.In contrast to many other scientific software projects, Dipy is not beingdeveloped by a single research group. Rather, it is an open project thatencourages contributions from any scientist/developer through GitHub and opendiscussions on the project mailing list. Consequently, Dipy today has aninternational team of contributors, spanning seven different academic institutionsin five countries and three continents, which is still growing.

  3. Haralick texture features from apparent diffusion coefficient (ADC) MRI images depend on imaging and pre-processing parameters.

    Science.gov (United States)

    Brynolfsson, Patrik; Nilsson, David; Torheim, Turid; Asklund, Thomas; Karlsson, Camilla Thellenberg; Trygg, Johan; Nyholm, Tufve; Garpebring, Anders

    2017-06-22

    In recent years, texture analysis of medical images has become increasingly popular in studies investigating diagnosis, classification and treatment response assessment of cancerous disease. Despite numerous applications in oncology and medical imaging in general, there is no consensus regarding texture analysis workflow, or reporting of parameter settings crucial for replication of results. The aim of this study was to assess how sensitive Haralick texture features of apparent diffusion coefficient (ADC) MR images are to changes in five parameters related to image acquisition and pre-processing: noise, resolution, how the ADC map is constructed, the choice of quantization method, and the number of gray levels in the quantized image. We found that noise, resolution, choice of quantization method and the number of gray levels in the quantized images had a significant influence on most texture features, and that the effect size varied between different features. Different methods for constructing the ADC maps did not have an impact on any texture feature. Based on our results, we recommend using images with similar resolutions and noise levels, using one quantization method, and the same number of gray levels in all quantized images, to make meaningful comparisons of texture feature results between different subjects.

  4. Alterations in the inferior longitudinal fasciculus in autism and associations with visual processing: a diffusion-weighted MRI study

    OpenAIRE

    Boets, Bart; Van Eylen, Lien; Sitek, Kevin; Moors, Pieter; Noens, Ilse; Steyaert, Jean; Sunaert, Stefan; Wagemans, Johan

    2018-01-01

    Background: One of the most reported neural features of autism spectrum disorder (ASD) is the alteration of multiple long-range white matter fiber tracts, as assessed by diffusion-weighted imaging and indexed by reduced fractional anisotropy (FA). Recent methodological advances, however, have shown that this same pattern of reduced FA may be an artifact resulting from excessive head motion and poorer data quality and that aberrant structural connectivity in children with ASD is confined to th...

  5. Diffusion-weighted MRI in cervical cancer

    International Nuclear Information System (INIS)

    McVeigh, Patrick Z.; Haider, Masoom A.; Syed, Aejaz M.; Milosevic, Michael; Fyles, Anthony

    2008-01-01

    The purpose was to investigate the potential value of apparent diffusion coefficient (ADC) measurement with MRI in the assessment of cervix cancer. Diffusion-weighted MRI was performed in 47 patients with cervical carcinoma undergoing chemoradiation therapy and 26 normal controls on a 1.5-T system with a b-value of 600 s/mm 2 . FIGO stage, tumor volume, nodal status, interstitial fluid pressure (IFP) and oxygen measurements were recorded. Response was defined as no visible tumor 3-6 months following completion of therapy. The average median ADC (mADC) of cervical carcinomas (1.09±0.20 x 10 -3 mm 2 /s) was significantly lower than normal cervix (2.09±0.46 x 10 -3 mm 2 /s) (P -3 mm 2 /s) compared to T2b (1.21 x 10 -3 mm 2 /s) and T3/T4 (1.10 x 10 -3 mm 2 /s) (P<0.001). In patients with squamous carcinomas the 90th percentile of ADC values was lower in responders than non-responders (P<0.05). Median ADC in cervix carcinoma is significantly lower compared to normal cervix. ADC may have predictive value in squamous tumors, but further long-term study will determine the ultimate clinical utility. (orig.)

  6. Fast and direct detection of neuronal activation with diffusion MRI

    International Nuclear Information System (INIS)

    Le Bihan, D.; Urayama, S.; Aso, T.; Hanakawa, T.; Fukuyama, H.

    2006-01-01

    conditions or in the presence of drugs. Also, it has been pointed out that the spatial functional resolution of vascular based functional neuroimaging might be limited, because vessels responsible for the increase of blood flow and blood volume feed or drain somewhat large territories which include clusters of neurons with potentially different functions. Similarly the physiological delay necessary for the mechanisms triggering the vascular response to work intrinsically limits the temporal resolution of BOLD f MRI. On the other hand, a fundamentally new paradigm is being proposed to look at brain activity through the observation with MRI of the diffusion behavior of the water molecules. It has been shown that the diffusion of water slightly slows down during brain activation. This slowdown, which occurs several seconds before the hemodynamic response detected by BOLD f MRI, has been described in terms of a phase transition of the water molecules in the cells undergoing activation and tentatively attributed to the swelling of those cells. This finding marks a significant departure from the former blood flow based PET and MRI approaches, and potentially offers improved spatial and temporal resolution, because the proposed mechanism appears more intimately linked to neuronal activation. However, the step might even extend further: Contrarily to the former approaches based on changes in artificially induced water physical properties, namely radioactivity and magnetization, required for the external PET or MR I detection, the new, diffusion based approach, merely uses MRI as a means to reveal changes in intrinsic water physical properties. These changes in the diffusion behaviour of water during activation seem to belong to an endogenous part of the activation process, and perhaps even more, could be an active component of this process that evolution has capitalized upon. The aim of this presentation is to review our current knowledge on the water physical properties i n

  7. D-BRAIN : Anatomically accurate simulated diffusion MRI brain data

    NARCIS (Netherlands)

    Perrone, Daniele; Jeurissen, Ben; Aelterman, Jan; Roine, Timo; Sijbers, Jan; Pizurica, Aleksandra; Leemans, Alexander; Philips, Wilfried

    2016-01-01

    Diffusion Weighted (DW) MRI allows for the non-invasive study of water diffusion inside living tissues. As such, it is useful for the investigation of human brain white matter (WM) connectivity in vivo through fiber tractography (FT) algorithms. Many DW-MRI tailored restoration techniques and FT

  8. Survey on visualization and analysis techniques based on diffusion MRI for in-vivo anisotropic diffusion structures

    International Nuclear Information System (INIS)

    Masutani, Yoshitaka; Sato, Tetsuo; Urayama, Shin-ichi; Bihan, D.L.

    2008-01-01

    In association with development of diffusion MR imaging technologies for anisotropic diffusion measurement in living body, related research is explosively increasing including research fields of applied mathematics and visualization in addition to MR imaging, biomedical image technology, and medical science. One of the reasons is that the diffusion MRI data set is a set of high dimensional image information beyond conventional scalar or vector images, and is attractive for the researchers in the related fields. This survey paper is mainly aimed at introducing state-of-the-art of post processing techniques reported in the literature for diffusion MRI data, such as analysis and visualization. (author)

  9. Measurements of brain microstructure and connectivity with diffusion MRI

    Directory of Open Access Journals (Sweden)

    Ching-Po Lin

    2011-12-01

    Full Text Available By probing direction-dependent diffusivity of water molecules, diffusion MRI has shown its capability to reflect the microstructural tissue status and to estimate the neural orientation and pathways in the living brain. This approach has supplied novel insights into in-vivo human brain connections. By detecting the connection patterns, anatomical architecture and structural integrity between cortical regions or subcortical nuclei in the living human brain can be easily identified. It thus opens a new window on brain connectivity studies and disease processes. During the past years, there is a growing interest in exploring the connectivity patterns of the human brain. Specifically, the utilities of noninvasive neuroimaging data and graph theoretical analysis have provided important insights into the anatomical connections and topological pattern of human brain structural networks in vivo. Here, we review the progress of this important technique and the recent methodological and application studies utilizing graph theoretical approaches on brain structural networks with structural MRI and diffusion MRI.

  10. D-BRAIN : Anatomically accurate simulated diffusion MRI brain data

    OpenAIRE

    Perrone, Daniele; Jeurissen, Ben; Aelterman, Jan; Roine, Timo; Sijbers, Jan; Pizurica, Aleksandra; Leemans, Alexander; Philips, Wilfried

    2016-01-01

    Diffusion Weighted (DW) MRI allows for the non-invasive study of water diffusion inside living tissues. As such, it is useful for the investigation of human brain white matter (WM) connectivity in vivo through fiber tractography (FT) algorithms. Many DW-MRI tailored restoration techniques and FT algorithms have been developed. However, it is not clear how accurately these methods reproduce the WM bundle characteristics in real-world conditions, such as in the presence of noise, partial volume...

  11. Diffusion-weighted MRI in acute posterior ischemic optic neuropathy

    International Nuclear Information System (INIS)

    Srinivasan, Sivasubramanian; Moorthy, Srikant; Sreekumar, KP; Kulkarni, Chinmay

    2012-01-01

    Blindness following surgery, especially cardiac surgery, has been reported sporadically, the most common cause being ischemic optic neuropathy. The role of MRI in the diagnosis of this condition is not well established. We present a case of postoperative posterior ischemic optic neuropathy that was diagnosed on diffusion-weighted MRI

  12. Robust and fast nonlinear optimization of diffusion MRI microstructure models.

    Science.gov (United States)

    Harms, R L; Fritz, F J; Tobisch, A; Goebel, R; Roebroeck, A

    2017-07-15

    Advances in biophysical multi-compartment modeling for diffusion MRI (dMRI) have gained popularity because of greater specificity than DTI in relating the dMRI signal to underlying cellular microstructure. A large range of these diffusion microstructure models have been developed and each of the popular models comes with its own, often different, optimization algorithm, noise model and initialization strategy to estimate its parameter maps. Since data fit, accuracy and precision is hard to verify, this creates additional challenges to comparability and generalization of results from diffusion microstructure models. In addition, non-linear optimization is computationally expensive leading to very long run times, which can be prohibitive in large group or population studies. In this technical note we investigate the performance of several optimization algorithms and initialization strategies over a few of the most popular diffusion microstructure models, including NODDI and CHARMED. We evaluate whether a single well performing optimization approach exists that could be applied to many models and would equate both run time and fit aspects. All models, algorithms and strategies were implemented on the Graphics Processing Unit (GPU) to remove run time constraints, with which we achieve whole brain dataset fits in seconds to minutes. We then evaluated fit, accuracy, precision and run time for different models of differing complexity against three common optimization algorithms and three parameter initialization strategies. Variability of the achieved quality of fit in actual data was evaluated on ten subjects of each of two population studies with a different acquisition protocol. We find that optimization algorithms and multi-step optimization approaches have a considerable influence on performance and stability over subjects and over acquisition protocols. The gradient-free Powell conjugate-direction algorithm was found to outperform other common algorithms in terms of

  13. Fast and direct detection of neuronal activation with diffusion MRI

    Energy Technology Data Exchange (ETDEWEB)

    Le Bihan, D. [Service Hospitalier Frederic Joliot (CEA/DSV/DRM), Lab. Anatomical and Functional Neuroimaging, 91 - Orsay (France); Urayama, S.; Aso, T.; Hanakawa, T.; Fukuyama, H. [Kyoto Univ. Graduate School of Medicine, Human Brain Research Center, Kyoto (Japan)

    2006-07-01

    pathological conditions or in the presence of drugs. Also, it has been pointed out that the spatial functional resolution of vascular based functional neuroimaging might be limited, because vessels responsible for the increase of blood flow and blood volume feed or drain somewhat large territories which include clusters of neurons with potentially different functions. Similarly the physiological delay necessary for the mechanisms triggering the vascular response to work intrinsically limits the temporal resolution of BOLD f MRI. On the other hand, a fundamentally new paradigm is being proposed to look at brain activity through the observation with MRI of the diffusion behavior of the water molecules. It has been shown that the diffusion of water slightly slows down during brain activation. This slowdown, which occurs several seconds before the hemodynamic response detected by BOLD f MRI, has been described in terms of a phase transition of the water molecules in the cells undergoing activation and tentatively attributed to the swelling of those cells. This finding marks a significant departure from the former blood flow based PET and MRI approaches, and potentially offers improved spatial and temporal resolution, because the proposed mechanism appears more intimately linked to neuronal activation. However, the step might even extend further: Contrarily to the former approaches based on changes in artificially induced water physical properties, namely radioactivity and magnetization, required for the external PET or MR I detection, the new, diffusion based approach, merely uses MRI as a means to reveal changes in intrinsic water physical properties. These changes in the diffusion behaviour of water during activation seem to belong to an endogenous part of the activation process, and perhaps even more, could be an active component of this process that evolution has capitalized upon. The aim of this presentation is to review our current knowledge on the water physical properties

  14. Conventions and nomenclature for double diffusion encoding NMR and MRI

    DEFF Research Database (Denmark)

    Shemesh, Noam; Jespersen, Sune N; Alexander, Daniel C

    2015-01-01

    , such as double diffusion encoding (DDE) NMR and MRI, may provide novel quantifiable metrics that are less easily inferred from conventional diffusion acquisitions. Despite the growing interest on the topic, the terminology for the pulse sequences, their parameters, and the metrics that can be derived from them...

  15. Purulent meningitis with unusual diffusion-weighted MRI findings

    International Nuclear Information System (INIS)

    Abe, M.; Takayama, Y.; Yamashita, H.; Noguchi, M.; Sagoh, T.

    2002-01-01

    We describe unusual findings obtained by diffusion-weighted magnetic resonance imaging (MRI) in a patient with acute purulent meningitis caused by penicillin-resistant Streptococcus pneumoniae. Along cerebral convexities and the Sylvian fissure, multiple small intense lesions showed high signal intensity in these sequences. This may be the first report of diffusion-weighted in purulent meningitis

  16. The importance of correcting for signal drift in diffusion MRI

    OpenAIRE

    Vos, Sjoerd B; Tax, Chantal M W; Luijten, Peter R; Ourselin, Sebastien; Leemans, Alexander; Froeling, Martijn

    2017-01-01

    PURPOSE: To investigate previously unreported effects of signal drift as a result of temporal scanner instability on diffusion MRI data analysis and to propose a method to correct this signal drift. METHODS: We investigated the signal magnitude of non-diffusion-weighted EPI volumes in a series of diffusion-weighted imaging experiments to determine whether signal magnitude changes over time. Different scan protocols and scanners from multiple vendors were used to verify this on phantom data, a...

  17. Multidimensional diffusion processes

    CERN Document Server

    Stroock, Daniel W

    1997-01-01

    From the reviews: "… Both the Markov-process approach and the Itô approach … have been immensely successful in diffusion theory. The Stroock-Varadhan book, developed from the historic 1969 papers by its authors, presents the martingale-problem approach as a more powerful - and, in certain regards, more intrinsic-means of studying the foundations of the subject. […] … the authors make the uncompromising decision not "to proselytise by intimidating the reader with myriad examples demonstrating the full scope of the techniques", but rather to persuade the reader "with a careful treatment of just one problem to which they apply". […] Most of the main tools of stochastic-processes theory are used, ..but it is the formidable combination of probability theory with analysis … which is the core of the work. […] I have emphasized the great importance of the Stroock-Varadhan book. It contains a lot more than I have indicated; in particular, its many exercises conain much interesting material. For immediat...

  18. Continuous diffusion signal, EAP and ODF estimation via Compressive Sensing in diffusion MRI.

    Science.gov (United States)

    Merlet, Sylvain L; Deriche, Rachid

    2013-07-01

    In this paper, we exploit the ability of Compressed Sensing (CS) to recover the whole 3D Diffusion MRI (dMRI) signal from a limited number of samples while efficiently recovering important diffusion features such as the Ensemble Average Propagator (EAP) and the Orientation Distribution Function (ODF). Some attempts to use CS in estimating diffusion signals have been done recently. However, this was mainly an experimental insight of CS capabilities in dMRI and the CS theory has not been fully exploited. In this work, we also propose to study the impact of the sparsity, the incoherence and the RIP property on the reconstruction of diffusion signals. We show that an efficient use of the CS theory enables to drastically reduce the number of measurements commonly used in dMRI acquisitions. Only 20-30 measurements, optimally spread on several b-value shells, are shown to be necessary, which is less than previous attempts to recover the diffusion signal using CS. This opens an attractive perspective to measure the diffusion signals in white matter within a reduced acquisition time and shows that CS holds great promise and opens new and exciting perspectives in diffusion MRI (dMRI). Copyright © 2013 Elsevier B.V. All rights reserved.

  19. Tuberous sclerosis: diffusion MRI findings in the brain

    International Nuclear Information System (INIS)

    Sener, R.N.

    2002-01-01

    Diffusion MRI has mainly been used for detection of acute ischemia, and for distinction of cytotoxic and vasogenic edema. We applied diffusion MRI in patients with tuberous sclerosis in order to evaluate diffusion imaging characteristics of parenchymal changes. Five children with known tuberous sclerosis were included in this study. The MRI examinations were performed on a 1.5-T MR unit. Diffusion MRI was obtained using the echo-planar imaging sequence. Apparent diffusion coefficient (ADC) values from the abnormal brain parenchyma were calculated directly from automatically generated ADC maps. Seven normal children were available for comparison. In this control group the mean ADC value of the normal white matter was 0.84±0.12 x 10 -3 mm 2 /s. In tuberous sclerosis patients the mean ADC value of the white matter hamartomas (n=20) was apparently high (1.52±0.24 x 10 -3 mm 2 /s) compared with that of normal white matter. The ADC value of calcified hamartomas was ''zero''. The ADC value within a giant cell tumor was 0.89 x 10 -3 mm 2 /s, similar to that of normal cerebral white matter. The ADC maps were superior to b=1000 s/mm 2 (true diffusion) images with respect to lesion evaluation, and they provided mathematical information on tissue integrity. With respect to detection of the exact numbers and sizes of the parenchymal hamartomas fluid-attenuated inversion recovery images were superior to ADC maps. It is believed that diffusion MRI can be useful in evaluation of various parenchymal changes associated with tuberous sclerosis. Further studies on tuberous sclerosis, and on various brain lesions, would provide increasing data on this relatively new MRI sequence. (orig.)

  20. Abnormal diffusion-weighted MRI in medulloblastoma: does it reflect small cell histology?

    International Nuclear Information System (INIS)

    Kotsenas, A.L.; Roth, T.C.; Manness, W.K.; Faerber, E.N.

    1999-01-01

    A 12-year-old boy presented with the classic CT and MRI findings of medulloblastoma and the unusual finding of increased signal on diffusion MRI. The small-cell histology of medulloblastoma may account for the increased signal seen on diffusion MRI. Diffusion MRI with echoplanar technique may be useful in evaluation of these tumors and metastatic disease. (orig.)

  1. White matter biomarkers from diffusion MRI

    Science.gov (United States)

    Nørhøj Jespersen, Sune

    2018-06-01

    As part of an issue celebrating 2 decades of Joseph Ackerman editing the Journal of Magnetic Resonance, this paper reviews recent progress in one of the many areas in which Ackerman and his lab has made significant contributions: NMR measurement of diffusion in biological media, specifically in brain tissue. NMR diffusion signals display exquisite sensitivity to tissue microstructure, and have the potential to offer quantitative and specific information on the cellular scale orders of magnitude below nominal image resolution when combined with biophysical modeling. Here, I offer a personal perspective on some recent advances in diffusion imaging, from diffusion kurtosis imaging to microstructural modeling, and the connection between the two. A new result on the estimation accuracy of axial and radial kurtosis with axially symmetric DKI is presented. I moreover touch upon recently suggested generalized diffusion sequences, promising to offer independent microstructural information. We discuss the need and some methods for validation, and end with an outlook on some promising future directions.

  2. Associations among q-space MRI, diffusion-weighted MRI and histopathological parameters in meningiomas

    Energy Technology Data Exchange (ETDEWEB)

    Fatima, Zareen; Motosugi, Utaroh; Ishigame, Keiichi; Araki, Tsutomu [University of Yamanashi, Department of Radiology, Chuo-shi, Yamanashi (Japan); Waqar, Ahmed Bilal [University of Yamanashi, Department of Molecular Pathology, Interdisciplinary Graduate School of Medicine and Engineering, Chuo-shi, Yamanashi (Japan); Hori, Masaaki [Juntendo University, Department of Radiology, School of Medicine, Tokyo (Japan); Oishi, Naoki; Katoh, Ryohei [University of Yamanashi, Department of Pathology, Chuo-shi, Yamanashi (Japan); Onodera, Toshiyuki; Yagi, Kazuo [Tokyo Metropolitan University, Department of Radiological Sciences, Graduate School of Human Health Sciences, Tokyo (Japan)

    2013-08-15

    The purposes of this MR-based study were to calculate q-space imaging (QSI)-derived mean displacement (MDP) in meningiomas, to evaluate the correlation of MDP values with apparent diffusion coefficient (ADC) and to investigate the relationships among these diffusion parameters, tumour cell count (TCC) and MIB-1 labelling index (LI). MRI, including QSI and conventional diffusion-weighted imaging (DWI), was performed in 44 meningioma patients (52 lesions). ADC and MDP maps were acquired from post-processing of the data. Quantitative analyses of these maps were performed by applying regions of interest. Pearson correlation coefficients were calculated for ADC and MDP in all lesions and for ADC and TCC, MDP and TCC, ADC and MIB-1 LI, and MDP and MIB-1 LI in 17 patients who underwent subsequent surgery. ADC and MDP values were found to have a strong correlation: r = 0.78 (P = <0.0001). Both ADC and MDP values had a significant negative association with TCC: r = -0.53 (p = 0.02) and -0.48 (P = 0.04), respectively. MIB-1 LI was not, however, found to have a significant association with these diffusion parameters. In meningiomas, both ADC and MDP may be representative of cell density. (orig.)

  3. Associations among q-space MRI, diffusion-weighted MRI and histopathological parameters in meningiomas

    International Nuclear Information System (INIS)

    Fatima, Zareen; Motosugi, Utaroh; Ishigame, Keiichi; Araki, Tsutomu; Waqar, Ahmed Bilal; Hori, Masaaki; Oishi, Naoki; Katoh, Ryohei; Onodera, Toshiyuki; Yagi, Kazuo

    2013-01-01

    The purposes of this MR-based study were to calculate q-space imaging (QSI)-derived mean displacement (MDP) in meningiomas, to evaluate the correlation of MDP values with apparent diffusion coefficient (ADC) and to investigate the relationships among these diffusion parameters, tumour cell count (TCC) and MIB-1 labelling index (LI). MRI, including QSI and conventional diffusion-weighted imaging (DWI), was performed in 44 meningioma patients (52 lesions). ADC and MDP maps were acquired from post-processing of the data. Quantitative analyses of these maps were performed by applying regions of interest. Pearson correlation coefficients were calculated for ADC and MDP in all lesions and for ADC and TCC, MDP and TCC, ADC and MIB-1 LI, and MDP and MIB-1 LI in 17 patients who underwent subsequent surgery. ADC and MDP values were found to have a strong correlation: r = 0.78 (P = <0.0001). Both ADC and MDP values had a significant negative association with TCC: r = -0.53 (p = 0.02) and -0.48 (P = 0.04), respectively. MIB-1 LI was not, however, found to have a significant association with these diffusion parameters. In meningiomas, both ADC and MDP may be representative of cell density. (orig.)

  4. Advanced diffusion processes and phenomena

    CERN Document Server

    Öchsner, Andreas; Belova, Irina

    2014-01-01

    This topical volume on Advanced Diffusion Processes and Phenomena addresses diffusion in a wider sense of not only mass diffusion but also heat diffusion in fluids and solids. Both diffusion phenomena play an important role in the characterization of engineering materials and corresponding structures. Understanding these different transport phenomena at many levels, from atomistic to macro, has therefore long attracted the attention of many researchers in materials science and engineering and related disciplines. The present topical volume captures a representative cross-section of some of the

  5. MRI of chemical reactions and processes.

    Science.gov (United States)

    Britton, Melanie M

    2017-08-01

    As magnetic resonance imaging (MRI) can spatially resolve a wealth of molecular information available from nuclear magnetic resonance (NMR), it is able to non-invasively visualise the composition, properties and reactions of a broad range of spatially-heterogeneous molecular systems. Hence, MRI is increasingly finding applications in the study of chemical reactions and processes in a diverse range of environments and technologies. This article will explain the basic principles of MRI and how it can be used to visualise chemical composition and molecular properties, providing an overview of the variety of information available. Examples are drawn from the disciplines of chemistry, chemical engineering, environmental science, physics, electrochemistry and materials science. The review introduces a range of techniques used to produce image contrast, along with the chemical and molecular insight accessible through them. Methods for mapping the distribution of chemical species, using chemical shift imaging or spatially-resolved spectroscopy, are reviewed, as well as methods for visualising physical state, temperature, current density, flow velocities and molecular diffusion. Strategies for imaging materials with low signal intensity, such as those containing gases or low sensitivity nuclei, using compressed sensing, para-hydrogen or polarisation transfer, are discussed. Systems are presented which encapsulate the diversity of chemical and physical parameters observable by MRI, including one- and two-phase flow in porous media, chemical pattern formation, phase transformations and hydrodynamic (fingering) instabilities. Lastly, the emerging area of electrochemical MRI is discussed, with studies presented on the visualisation of electrochemical deposition and dissolution processes during corrosion and the operation of batteries, supercapacitors and fuel cells. Crown Copyright © 2017. Published by Elsevier B.V. All rights reserved.

  6. Diffusion-weighted MRI of maple syrup urine disease encephalopathy

    Energy Technology Data Exchange (ETDEWEB)

    Cavalleri, F.; Mavilla, L. [Servizio di Neuroradiologia, Azienda Ospedaliera Policlinico, Modena (Italy); Berardi, A.; Ferrari, F. [Servizio di Neonatologia, Azienda Ospedaliera Policlinico, Modena (Italy); Burlina, A.B. [Dipartimento di Pediatria, Azienda Ospedaliera, Universita di Padova, Padua (Italy)

    2002-06-01

    We report the case of a newborn child with maple syrup urine disease (MSUD), diagnosed at 10 days of life. Diffusion-weighted echoplanar MRI showed marked hyperintensity of the cerebellar white matter, the brainstem, the cerebral peduncles, the thalami, the dorsal limb of the internal capsule and the centrum semiovale, while conventional dual-echo sequence evidenced only a weak diffuse T2 hyperintensity in the cerebellar white matter and in the dorsal brainstem. The apparent diffusion coefficient (ADC) of these regions was markedly (>80%) decreased. Therefore, in agreement with current hypotheses on MSUD pathogenesis, MSUD oedema proves to be a cytotoxic oedema. Diffusion-weighted MRI may be a valuable tool, more sensitive than conventional spin-echo techniques, to assess the extent and progression of cytotoxicity in MSUD, as well as the effectiveness of the therapeutic interventions. (orig.)

  7. Diffusion-weighted MRI of maple syrup urine disease encephalopathy

    International Nuclear Information System (INIS)

    Cavalleri, F.; Mavilla, L.; Berardi, A.; Ferrari, F.; Burlina, A.B.

    2002-01-01

    We report the case of a newborn child with maple syrup urine disease (MSUD), diagnosed at 10 days of life. Diffusion-weighted echoplanar MRI showed marked hyperintensity of the cerebellar white matter, the brainstem, the cerebral peduncles, the thalami, the dorsal limb of the internal capsule and the centrum semiovale, while conventional dual-echo sequence evidenced only a weak diffuse T2 hyperintensity in the cerebellar white matter and in the dorsal brainstem. The apparent diffusion coefficient (ADC) of these regions was markedly (>80%) decreased. Therefore, in agreement with current hypotheses on MSUD pathogenesis, MSUD oedema proves to be a cytotoxic oedema. Diffusion-weighted MRI may be a valuable tool, more sensitive than conventional spin-echo techniques, to assess the extent and progression of cytotoxicity in MSUD, as well as the effectiveness of the therapeutic interventions. (orig.)

  8. Complete Fourier Direct Magnetic Resonance Imaging (CFD-MRI for Diffusion MRI

    Directory of Open Access Journals (Sweden)

    Alpay eÖzcan

    2013-04-01

    Full Text Available 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.

  9. White matter biomarkers from diffusion MRI

    DEFF Research Database (Denmark)

    Jespersen, Sune

    2018-01-01

    Abstract As part of an issue celebrating 2 decades of Joseph Ackerman editing the Journal of Magnetic Resonance, this paper reviews recent progress in one of the many areas in which Ackerman and his lab has made significant contributions: NMR measurement of diffusion in biological media, specific...

  10. Image quality transfer and applications in diffusion MRI

    DEFF Research Database (Denmark)

    Alexander, Daniel C.; Zikic, Darko; Ghosh, Aurobrata

    2017-01-01

    and the uniquely rich diffusion MRI data set from the human connectome project (HCP). Results highlight potential benefits of IQT in both brain connectivity mapping and microstructure imaging. In brain connectivity mapping, IQT reveals, from standard data sets, thin connection pathways that tractography normally...

  11. Cumulant expansions for measuring water exchange using diffusion MRI

    Science.gov (United States)

    Ning, Lipeng; Nilsson, Markus; Lasič, Samo; Westin, Carl-Fredrik; Rathi, Yogesh

    2018-02-01

    The rate of water exchange across cell membranes is a parameter of biological interest and can be measured by diffusion magnetic resonance imaging (dMRI). In this work, we investigate a stochastic model for the diffusion-and-exchange of water molecules. This model provides a general solution for the temporal evolution of dMRI signal using any type of gradient waveform, thereby generalizing the signal expressions for the Kärger model. Moreover, we also derive a general nth order cumulant expansion of the dMRI signal accounting for water exchange, which has not been explored in earlier studies. Based on this analytical expression, we compute the cumulant expansion for dMRI signals for the special case of single diffusion encoding (SDE) and double diffusion encoding (DDE) sequences. Our results provide a theoretical guideline on optimizing experimental parameters for SDE and DDE sequences, respectively. Moreover, we show that DDE signals are more sensitive to water exchange at short-time scale but provide less attenuation at long-time scale than SDE signals. Our theoretical analysis is also validated using Monte Carlo simulations on synthetic structures.

  12. New MRI technologies. Diffusion MRI and its application to functional neuroimaging and analyses of white matter integrity

    International Nuclear Information System (INIS)

    Kobayashi, Tetsuo

    2010-01-01

    Described is the technological aspect of MRI, MR diffusion-weighted imaging (MR-DWI), principles of its measurement and application for imaging the cerebral function and for aiding the quantitative diagnosis of brain diseases. The author explains the principle of MR imaging process; diffusion properties of water molecules, MR-DWI based on them and DW-fMRI of the brain; MR-diffusion tensor imaging (MR-DTI), its analysis and color acquisition, and tracking of white matter nerve fibers; analysis of white matter lesions by the tracking; and the new tracking method at the chiasm of nerve fascicles. The usual fMRI reflects the blood oxygen level depending (BOLD) signals whereas recently attracted DW-fMRI, the volume changes of nerve cells concomitant to nerve activation accompanying apparent changes of water diffusion coefficients in and out of cells which occur faster than BOLD signs, resulting in higher resolution of time and space. However, DWI requires the higher intensity of static magnetic field like 3T. MR-DTI acquires the anisotropic diffusion of water molecules using MR-DWI technique with application of 6 or more motion probing gradients, thus makes it possible to track the running directions of nerve fibers and capillary vessels, and is proposed to be a useful mean of specific fiber tracking in the white matter when displayed by 3 different colors exhibiting the directions like the right/left (x axis, red), anterior/posterior (y, green) and upper/lower (z, blue) sides of head. Recently, MR-DWI and MR-DTI have been found usable for pathogenic studies of brain diseases such as dementia. Tensor anisotropy is apparently lowered at the chiasm of nerve fascicles, the cause of tracking error, for which authors have developed a new method using the similarity of directional vector, not of tensor, before and behind the chiasm. As exemplified, MRI technology is further advancing even at present. (T.T.)

  13. Quantifying brain microstructure with diffusion MRI

    DEFF Research Database (Denmark)

    Novikov, Dmitry S.; Jespersen, Sune N.; Kiselev, Valerij G.

    2016-01-01

    the potential to quantify the relevant length scales for neuronal tissue, such as the packing correlation length for neuronal fibers, the degree of neuronal beading, and compartment sizes. The second avenue corresponds to the long-time limit, when the observed signal can be approximated as a sum of multiple non......-exchanging anisotropic Gaussian components. Here the challenge lies in parameter estimation and in resolving its hidden degeneracies. The third avenue employs multiple diffusion encoding techniques, able to access information not contained in the conventional diffusion propagator. We conclude with our outlook...... on the future research directions which can open exciting possibilities for developing markers of pathology and development based on methods of studying mesoscopic transport in disordered systems....

  14. Diffusion MRI: Mitigation of Magnetic Field Inhomogeneities

    Czech Academy of Sciences Publication Activity Database

    Marcon, P.; Bartušek, Karel; Dokoupil, Zdeněk; Gescheidtová, E.

    2012-01-01

    Roč. 12, č. 5 (2012), s. 205-212 ISSN 1335-8871 R&D Projects: GA MŠk ED0017/01/01; GA ČR GAP102/11/0318; GA ČR GAP102/12/1104 Institutional support: RVO:68081731 Keywords : correction * diffusion * inhomogeneity * eddy currents * magnetic resonance Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.233, year: 2012

  15. Bayesian uncertainty quantification in linear models for diffusion MRI.

    Science.gov (United States)

    Sjölund, Jens; Eklund, Anders; Özarslan, Evren; Herberthson, Magnus; Bånkestad, Maria; Knutsson, Hans

    2018-03-29

    Diffusion MRI (dMRI) is a valuable tool in the assessment of tissue microstructure. By fitting a model to the dMRI signal it is possible to derive various quantitative features. Several of the most popular dMRI signal models are expansions in an appropriately chosen basis, where the coefficients are determined using some variation of least-squares. However, such approaches lack any notion of uncertainty, which could be valuable in e.g. group analyses. In this work, we use a probabilistic interpretation of linear least-squares methods to recast popular dMRI models as Bayesian ones. This makes it possible to quantify the uncertainty of any derived quantity. In particular, for quantities that are affine functions of the coefficients, the posterior distribution can be expressed in closed-form. We simulated measurements from single- and double-tensor models where the correct values of several quantities are known, to validate that the theoretically derived quantiles agree with those observed empirically. We included results from residual bootstrap for comparison and found good agreement. The validation employed several different models: Diffusion Tensor Imaging (DTI), Mean Apparent Propagator MRI (MAP-MRI) and Constrained Spherical Deconvolution (CSD). We also used in vivo data to visualize maps of quantitative features and corresponding uncertainties, and to show how our approach can be used in a group analysis to downweight subjects with high uncertainty. In summary, we convert successful linear models for dMRI signal estimation to probabilistic models, capable of accurate uncertainty quantification. Copyright © 2018 Elsevier Inc. All rights reserved.

  16. Axon diameter mapping in crossing fibers with diffusion MRI

    DEFF Research Database (Denmark)

    Zhang, Hui; Dyrby, Tim B; Alexander, Daniel C

    2011-01-01

    This paper proposes a technique for a previously unaddressed problem, namely, mapping axon diameter in crossing fiber regions, using diffusion MRI. Direct measurement of tissue microstructure of this kind using diffusion MRI offers a new class of biomarkers that give more specific information about...... tissue than measures derived from diffusion tensor imaging. Most existing techniques for axon diameter mapping assume a single axon orientation in the tissue model, which limits their application to only the most coherently oriented brain white matter, such as the corpus callosum, where the single...... model to enable axon diameter mapping in voxels with crossing fibers. We show in simulation that the technique can provide robust axon diameter estimates in a two-fiber crossing with the crossing angle as small as 45 degrees. Using ex vivo imaging data, we further demonstrate the feasibility...

  17. MRI findings in acute diffuse axonal injured patients

    International Nuclear Information System (INIS)

    Sato, Hidetaka

    2001-01-01

    Diffuse axonal injury (DAI) in the acute stage was clinically evaluated using magnetic resonance imaging (MRI), which is considered superior to computed tomography (CT) in detecting parenchymal brain lesions. MRI was disadvantageous, however, to patients suffering from acute severe head injury because of the long time required to construct imaging and unstable patient vital signs. We conducted MRI safely under a high magnetic field (1.5 tesla) in acute DAI by close observation and with nonmagnetic respirator and electrocardiographic monitoring. MRI was conducted in 95 patients diagnosed with DAI classified into mild (14), moderate (17) and severe (64) DAI by criteria established by Gennarelli (1986). In patients with mild or moderate DAI, CT revealed no lesion in the parenchymal area although MRI detected lesions in every case, mainly in cortical white matter or basal ganglia. In patients with severe DAI, CT revealed parenchymal lesions in 14 although MRI detected further lesions in cortical white matter, basal ganglia, corpus callosum and brainstem in every case. These results correspond well to the experimental model Gennarelli's. This study concluded that MRI was useful in assessing acute DAI patients. (author)

  18. Modifications of pancreatic diffusion MRI by tissue characteristics: what are we weighting for?

    Science.gov (United States)

    Nissan, Noam

    2017-08-01

    Diffusion-weighted imaging holds the potential to improve the diagnosis and biological characterization of pancreatic disease, and in particular pancreatic cancer, which exhibits decreased values of the apparent diffusion coefficient (ADC). Yet, variable and overlapping ADC values have been reported for the healthy and the pathological pancreas, including for cancer and other benign conditions. This controversy reflects the complexity of probing the water-diffusion process in the pancreas, which is dependent upon multiple biological factors within this organ's unique physiological environment. In recent years, extensive studies have investigated the correlation between tissue properties including cellularity, vascularity, fibrosis, secretion and microstructure and pancreatic diffusivity. Understanding how the various physiological and pathological features and the underlying functional processes affect the diffusion measurement may serve to optimize the method for improved diagnostic gain. Therefore, the aim of the present review article is to elucidate the relationship between pancreatic tissue characteristics and diffusion MRI measurement. Copyright © 2017 John Wiley & Sons, Ltd.

  19. Altered structure-function relations of semantic processing in youths with high-functioning autism: a combined diffusion and functional MRI study.

    Science.gov (United States)

    Lo, Yu-Chun; Chou, Tai-Li; Fan, Li-Ying; Gau, Susan Shur-Fen; Chiu, Yen-Nan; Tseng, Wen-Yih Isaac

    2013-12-01

    Deficits in language and communication are among the core symptoms of autism, a common neurodevelopmental disorder with long-term impairment. Despite the striking nature of the autistic language impairment, knowledge about its corresponding alterations in the brain is still evolving. We hypothesized that the dual stream language network is altered in autism, and that this alteration could be revealed by changes in the relationships between microstructural integrity and functional activation. The study recruited 20 right-handed male youths with autism and 20 carefully matched individually, typically developing (TD) youths. Microstructural integrity of the left dorsal and left ventral pathways responsible for language processing and the functional activation of the connected brain regions were investigated by using diffusion spectrum imaging and functional magnetic resonance imaging of a semantic task, respectively. Youths with autism had significantly poorer language function, and lower functional activation in left dorsal and left ventral regions of the language network, compared with TD youths. The TD group showed a significant correlation of the functional activation of the left dorsal region with microstructural integrity of the left ventral pathway, whereas the autism group showed a significant correlation of the functional activation of the left ventral region with microstructural integrity of the left dorsal pathway, and moreover verbal comprehension index was correlated with microstructural integrity of the left ventral pathway. These altered structure-function relationships in autism suggest possible involvement of the dual pathways in supporting deficient semantic processing. © 2013 International Society for Autism Research, Wiley Periodicals, Inc.

  20. Diffusion-weighted MRI in shaken baby syndrome

    International Nuclear Information System (INIS)

    Chan, Yu-Leung; Chu, Winnie C.W.; Wong, Gary W.K.; Yeung, David K.W.

    2003-01-01

    We present the characteristic CT and MRI findings of a 2-month-old girl with shaken baby syndrome. Diffusion-weighted MR imaging performed 8 days after the insult established the presence of injury to the white matter in the corpus callosum and subcortical white matter in the temporo-occipito-parietal region. Diffusion-weighted MR imaging is valuable in the diagnostic work-up of suspected shaken baby syndrome, as injury to the white matter can be demonstrated days after the injury. (orig.)

  1. Brain microstructure mapping using quantitative and diffusion MRI

    International Nuclear Information System (INIS)

    Lebois, Alice

    2014-01-01

    This thesis is focused on the human brain microstructure mapping using quantitative and diffusion MRI. The T1/T2 quantitative imaging relies on sequences dedicated to the mapping of T1 and T2 relaxation times. Their variations within the tissue are linked to the presence of different water compartments defined by a specific organization of the tissue at the cell scale. Measuring these parameters can help, therefore, to better characterize the brain microstructure. The dMRI, on the other hand, explores the brownian motion of water molecules in the brain tissue, where the water molecules' movement is constrained by natural barriers, such as cell membranes. Thus, the information on their displacement carried by the dMRI signal gives access to the underlying cyto-architecture. Combination of these two modalities is, therefore, a promising way to probe the brain tissue microstructure. The main goal of the present thesis is to set up the methodology to study the microstructure of the white matter of the human brain in vivo. The first part includes the acquisition of a unique MRI database of 79 healthy subjects (the Archi/CONNECT), which includes anatomical high resolution data, relaxometry data, diffusion-weighted data at high spatio-angular resolution and functional data. This database has allowed us to build the first atlas of the anatomical connectivity of the healthy brain through the automatic segmentation of the major white matter bundles, providing an appropriate anatomical reference for the white matter to study individually the quantitative parameters along each fascicle, characterizing its microstructure organization. Emphasis was placed on the construction of the first atlas of the T1/T2 profiles along the major white matter pathways. The profiles of the T1 and T2 relaxation times were then correlated to the quantitative profiles computed from the diffusion MRI data (fractional anisotropy, radial and longitudinal diffusivities, apparent diffusion coefficient

  2. High angular resolution diffusion imaging : processing & visualization

    NARCIS (Netherlands)

    Prckovska, V.

    2010-01-01

    Diffusion tensor imaging (DTI) is a recent magnetic resonance imaging (MRI) technique that can map the orientation architecture of neural tissues in a completely non-invasive way by measuring the directional specificity (anisotropy) of the local water diffusion. However, in areas of complex fiber

  3. Diffusion-weighted MRI of myelination in the rat brain following treatment with gonadal hormones

    International Nuclear Information System (INIS)

    Prayer, D.; Roberts, T.; Barkovich, A.J.; Prayer, L.; Kucharczyk, J.; Moseley, M.; Arieff, A.

    1997-01-01

    Previous studies have demonstrated the ability of high-resolution diffusion-weighted MRI to show maturation of white-matter structures in the developing rat brain. The purpose of this study was to investigate the influence of gonadal steroid hormones on the rate of this development. Starting from their second postnatal day, 16 rat-pups of either sex were repeatedly treated with subcutaneous implants containing 17-beta estradiol or delta-androstene 3,17 dione, respectively. Serial T1-, T2- and diffusion-weighted MRI was performed weekly for 8 weeks using a 4.7 T unit. Maturation of anterior optic pathways and hemisphere commissures was assessed. Diffusion-weighted images were processed to produce ''anisotropy index maps'', previously shown to be sensitive to white-matter maturation. Compared with untreated rat-pups, estrogen-treated animals showed accelerated, and testosterone-treated animals delayed maturation on anisotropy index maps and histological sections. In all animals, maturational changes appeared earlie on anisotropy index maps than on other MRI sequences or on myelin-sensitive stained sections. Diffusion-weighted imaging, and the construction of spatial maps sensitive to diffusion anisotropy, seem to be the most sensitive approach for the detection of maturational white-matter changes, and thus may hold potential for early diagnosis of temporary delay or permanent disturbances of white-matter development. (orig.). With 6 figs., 1 tab

  4. Diffusion-weighted MRI of myelination in the rat brain following treatment with gonadal hormones

    Energy Technology Data Exchange (ETDEWEB)

    Prayer, D. [Department of Radiology, Section of Neuroradiology, University of Vienna (Austria); Roberts, T. [Department of Radiology, Section of Neuroradiology, University of California at San Francisco (UCSF), CA (United States); Barkovich, A.J. [Department of Radiology, Section of Neuroradiology, University of California at San Francisco (UCSF), CA (United States); Prayer, L. [Department of Radiology, Section of Neuroradiology, University of Vienna (Austria); Kucharczyk, J. [Department of Radiology, Section of Neuroradiology, University of California at San Francisco (UCSF), CA (United States); Moseley, M. [Department of Radiology, Section of Neuroradiology, University of California at San Francisco (UCSF), CA (United States); Arieff, A. [Department of Medicine, Geriatrics Section, Veteran`s Affairs Medical Center and University of California at San Francisco (UCSF), CA (United States)

    1997-05-01

    Previous studies have demonstrated the ability of high-resolution diffusion-weighted MRI to show maturation of white-matter structures in the developing rat brain. The purpose of this study was to investigate the influence of gonadal steroid hormones on the rate of this development. Starting from their second postnatal day, 16 rat-pups of either sex were repeatedly treated with subcutaneous implants containing 17-beta estradiol or delta-androstene 3,17 dione, respectively. Serial T1-, T2- and diffusion-weighted MRI was performed weekly for 8 weeks using a 4.7 T unit. Maturation of anterior optic pathways and hemisphere commissures was assessed. Diffusion-weighted images were processed to produce ``anisotropy index maps``, previously shown to be sensitive to white-matter maturation. Compared with untreated rat-pups, estrogen-treated animals showed accelerated, and testosterone-treated animals delayed maturation on anisotropy index maps and histological sections. In all animals, maturational changes appeared earlie on anisotropy index maps than on other MRI sequences or on myelin-sensitive stained sections. Diffusion-weighted imaging, and the construction of spatial maps sensitive to diffusion anisotropy, seem to be the most sensitive approach for the detection of maturational white-matter changes, and thus may hold potential for early diagnosis of temporary delay or permanent disturbances of white-matter development. (orig.). With 6 figs., 1 tab.

  5. Atypical abdominal paediatric lymphangiomatosis: diagnosis aided by diffusion-weighted MRI

    International Nuclear Information System (INIS)

    Humphries, Paul D.; Olsen, Oeystein E.; Wynne, Catherine S.; Sebire, Neil J.

    2006-01-01

    We report a 4-year-old child with a mesenteric mass, which on ultrasound, CT and conventional MRI appeared solid, raising lymphoma as a possible diagnosis. Diffusion weighted MRI (DW-MRI), however, suggested a low-cellularity lesion, making lymphoma less likely. Biopsy confirmed lymphangioma. DW-MRI may be a useful adjunct to conventional imaging, even in the abdomen. (orig.)

  6. Joint brain connectivity estimation from diffusion and functional MRI data

    Science.gov (United States)

    Chu, Shu-Hsien; Lenglet, Christophe; Parhi, Keshab K.

    2015-03-01

    Estimating brain wiring patterns is critical to better understand the brain organization and function. Anatomical brain connectivity models axonal pathways, while the functional brain connectivity characterizes the statistical dependencies and correlation between the activities of various brain regions. The synchronization of brain activity can be inferred through the variation of blood-oxygen-level dependent (BOLD) signal from functional MRI (fMRI) and the neural connections can be estimated using tractography from diffusion MRI (dMRI). Functional connections between brain regions are supported by anatomical connections, and the synchronization of brain activities arises through sharing of information in the form of electro-chemical signals on axon pathways. Jointly modeling fMRI and dMRI data may improve the accuracy in constructing anatomical connectivity as well as functional connectivity. Such an approach may lead to novel multimodal biomarkers potentially able to better capture functional and anatomical connectivity variations. We present a novel brain network model which jointly models the dMRI and fMRI data to improve the anatomical connectivity estimation and extract the anatomical subnetworks associated with specific functional modes by constraining the anatomical connections as structural supports to the functional connections. The key idea is similar to a multi-commodity flow optimization problem that minimizes the cost or maximizes the efficiency for flow configuration and simultaneously fulfills the supply-demand constraint for each commodity. In the proposed network, the nodes represent the grey matter (GM) regions providing brain functionality, and the links represent white matter (WM) fiber bundles connecting those regions and delivering information. The commodities can be thought of as the information corresponding to brain activity patterns as obtained for instance by independent component analysis (ICA) of fMRI data. The concept of information

  7. Mass diffusion coefficient measurement for vitreous humor using FEM and MRI

    Science.gov (United States)

    Rattanakijsuntorn, Komsan; Penkova, Anita; Sadha, Satwindar S.

    2018-01-01

    In early studies, the ‘contour method’ for determining the diffusion coefficient of the vitreous humor was developed. This technique relied on careful injection of an MRI contrast agent (surrogate drug) into the vitreous humor of fresh bovine eyes, and tracking the contours of the contrast agent in time. In addition, an analytical solution was developed for the theoretical contours built on point source model for the injected surrogate drug. The match between theoretical and experimental contours as a least square fit, while floating the diffusion coefficient, led to the value of the diffusion coefficient. This method had its limitation that the initial injection of the surrogate had to be spherical or ellipsoidal because of the analytical result based on the point-source model. With a new finite element model for the analysis in this study, the technique is much less restrictive and handles irregular shapes of the initial bolus. The fresh bovine eyes were used for drug diffusion study in the vitreous and three contrast agents of different molecular masses: gadolinium-diethylenetriaminepentaacetic acid (Gd-DTPA, 938 Da), non-ionic gadoteridol (Prohance, 559 Da), and bovine albumin conjugated with gadolinium (Galbumin, 74 kDa) were used as drug surrogates to visualize the diffusion process by MRI. The 3D finite element model was developed to determine the diffusion coefficients of these surrogates with the images from MRI. This method can be used for other types of bioporous media provided the concentration profile can be visualized (by methods such as MRI or fluorescence).

  8. Mapping human whole-brain structural networks with diffusion MRI.

    Directory of Open Access Journals (Sweden)

    Patric Hagmann

    Full Text Available Understanding the large-scale structural network formed by neurons is a major challenge in system neuroscience. A detailed connectivity map covering the entire brain would therefore be of great value. Based on diffusion MRI, we propose an efficient methodology to generate large, comprehensive and individual white matter connectional datasets of the living or dead, human or animal brain. This non-invasive tool enables us to study the basic and potentially complex network properties of the entire brain. For two human subjects we find that their individual brain networks have an exponential node degree distribution and that their global organization is in the form of a small world.

  9. Comparison of diffusion-weighted fMRI and BOLD fMRI responses in a verbal working memory task

    International Nuclear Information System (INIS)

    Aso, Toshihiko; Urayama, Shin-ichi; Fukuyama, Hidenao; Le Bihan, Denis

    2013-01-01

    Diffusion-weighted functional MRI (DfMRI) has been reported to have a different response pattern in the visual cortex than that of BOLD-fMRI. Especially, the DfMRI signal shows a constantly faster response at both onset and offset of the stimulus, suggesting that the DfMRI signal might be more directly linked to neuronal events than the hemodynamic response. However, because the DfMRI response also contains a residual sensitivity to BOLD this hypothesis has been challenged. Using a verbal working memory task we show that the DfMRI time-course features are preserved outside visual cortices, but also less liable to between-subject/between-regional variation than the BOLD response. The overall findings not only support the feasibility of DfMRI as an approach for functional brain imaging, but also strengthen the uniqueness of the DfMRI signal origin. (authors)

  10. Comparison of Biomarkers in Transgenic Alzheimer Rats Using Multi-shell Diffusion MRI

    OpenAIRE

    Fick , Rutger ,; Daianu , Madelaine; Pizzolato , Marco; Wassermann , Demian; Jacobs , Russel E.; Thompson , Paul M.; Town , Terrence; Deriche , Rachid

    2016-01-01

    International audience; In this study, we assessed the evolution of diffusion MRI (dMRI) derived markers from different white matter models as progressive neurodegeneration occurs in transgenic Alzheimer rats (TgF344-AD) at 10, 15 and 24 months. We compared biomarkers reconstructed from Diffusion Tensor Imaging (DTI), Neurite Orientation Dispersion and Density Imaging (NODDI) and Mean Apparent Propagator (MAP)-MRI in the hippocampus, cingulate cortex and corpus callosum using multi-shell dMRI...

  11. Diffusion-weighted MRI in acute cerebral stroke

    Energy Technology Data Exchange (ETDEWEB)

    Takayama, Hideichi; Kobayashi, Masahito; Suga, Sadao; Kawase, Takeshi; Nagasawa, Masakazu; Sadanaga, Humiko; Okamura, Miyuki; Kanai, Yoshihiro; Mihara, Ban [Mihara Memorial Hospital, Isezaki, Gunma (Japan)

    1999-03-01

    Diffusion-weighted MRI has been demonstrated to be valuable in the assessment of cerebral stroke. Recent advance in MR systems of hardware with larger maximum gradient amplitude and faster imaging strategies, such as EPI, has made it possible to acquire whole brain diffusion-weighted imaging (DWI) in less that one minute. The purposes of this study are to evaluate clinical usefulness of DWI and to clarify pitfalls in the diagnosis of acute cerebral stroke. Seventeen patients with 18 ischemic lesions were studied. DWI were taken with 1.5 Tesla MRI (Magnetom Vision, Siemens, Germany) using EPI sequence. Fifteen lesions out of them (3 in cerebral cortex, 9 in basal ganglia/deep white matter and 3 in cerebellum) were studied serially at various times up to 147 days. Acute cerebral infarction was seen clearly as an area of hyperintensity with DWI and as hypointensity in apparent diffusion coefficient (ADC) maps which are indicative of decreased diffusion. DWI detected areas of hyperintense acute infarcts, as early as 2.5 hours after onset, which were not visualized on T{sub 2}-weighted image (T2WI). The lesion of cerebral infarction became isointense in ADC maps at 14-28 days after onset, whereas with DWI it became isointense at about 2 months. Because ADC changed earlier than DWI, ADC maps were useful for differentiate acute from nonacute lesion in cases of recurrent stroke within a short period. In a patient with transient global amnesia for 7 hours, DWI did not show any lesion at 8 hours. In terms of cerebral hemorrhage, lesions were seen as area of hyperintensity in DWI at 3 days and were not distinguishable from that of infarct. Despite limitations in the diagnosis of transient ischemia and cerebral hemorrhage, DWI is a useful technique for early detection of cerebral infarction, especially within the first 6 hours after stroke onset. (author)

  12. Diffusion-weighted MRI in acute cerebral stroke

    International Nuclear Information System (INIS)

    Takayama, Hideichi; Kobayashi, Masahito; Suga, Sadao; Kawase, Takeshi; Nagasawa, Masakazu; Sadanaga, Humiko; Okamura, Miyuki; Kanai, Yoshihiro; Mihara, Ban

    1999-01-01

    Diffusion-weighted MRI has been demonstrated to be valuable in the assessment of cerebral stroke. Recent advance in MR systems of hardware with larger maximum gradient amplitude and faster imaging strategies, such as EPI, has made it possible to acquire whole brain diffusion-weighted imaging (DWI) in less that one minute. The purposes of this study are to evaluate clinical usefulness of DWI and to clarify pitfalls in the diagnosis of acute cerebral stroke. Seventeen patients with 18 ischemic lesions were studied. DWI were taken with 1.5 Tesla MRI (Magnetom Vision, Siemens, Germany) using EPI sequence. Fifteen lesions out of them (3 in cerebral cortex, 9 in basal ganglia/deep white matter and 3 in cerebellum) were studied serially at various times up to 147 days. Acute cerebral infarction was seen clearly as an area of hyperintensity with DWI and as hypointensity in apparent diffusion coefficient (ADC) maps which are indicative of decreased diffusion. DWI detected areas of hyperintense acute infarcts, as early as 2.5 hours after onset, which were not visualized on T 2 -weighted image (T2WI). The lesion of cerebral infarction became isointense in ADC maps at 14-28 days after onset, whereas with DWI it became isointense at about 2 months. Because ADC changed earlier than DWI, ADC maps were useful for differentiate acute from nonacute lesion in cases of recurrent stroke within a short period. In a patient with transient global amnesia for 7 hours, DWI did not show any lesion at 8 hours. In terms of cerebral hemorrhage, lesions were seen as area of hyperintensity in DWI at 3 days and were not distinguishable from that of infarct. Despite limitations in the diagnosis of transient ischemia and cerebral hemorrhage, DWI is a useful technique for early detection of cerebral infarction, especially within the first 6 hours after stroke onset. (author)

  13. Diffusion-weighted MRI of adult male pelvic cancers

    International Nuclear Information System (INIS)

    Lim, K.S.; Tan, C.H.

    2012-01-01

    Magnetic resonance imaging (MRI), with its superior soft-tissue delineation, plays a pivotal role in the staging and surveillance of cancers affecting adult males, in particular, rectal, urinary bladder, and prostate cancers. There has been much recent interest in the complementary roles of diffusion-weighted imaging (DWI) for imaging of pelvic cancers. DWI measures the diffusivity of water molecules in biological tissue. Cancer, with its high cellular density and nuclear:cytoplasmic ratio, and extracellular disorganization, typically shows significant restricted diffusivity compared with surrounding normal tissue. In theory, diffusivity of water molecules may vary according to degree of tumour aggressiveness and changes in cell density and extracellular fluid content after treatment. Information regarding these variations may be used to study the histological grades of cancers and their response to treatment. In this article, we present the currently available evidence on the potential roles of DWI for the assessment of pelvic cancers in men, and demonstrate with imaging examples how this knowledge may be applied to daily clinical practice.

  14. A 4-channel 3 Tesla phased array receive coil for awake rhesus monkey fMRI and diffusion MRI experiments.

    Science.gov (United States)

    Khachaturian, Mark Haig

    2010-01-01

    Awake monkey fMRI and diffusion MRI combined with conventional neuroscience techniques has the potential to study the structural and functional neural network. The majority of monkey fMRI and diffusion MRI experiments are performed with single coils which suffer from severe EPI distortions which limit resolution. By constructing phased array coils for monkey MRI studies, gains in SNR and anatomical accuracy (i.e., reduction of EPI distortions) can be achieved using parallel imaging. The major challenges associated with constructing phased array coils for monkeys are the variation in head size and space constraints. Here, we apply phased array technology to a 4-channel phased array coil capable of improving the resolution and image quality of full brain awake monkey fMRI and diffusion MRI experiments. The phased array coil is that can adapt to different rhesus monkey head sizes (ages 4-8) and fits in the limited space provided by monkey stereotactic equipment and provides SNR gains in primary visual cortex and anatomical accuracy in conjunction with parallel imaging and improves resolution in fMRI experiments by a factor of 2 (1.25 mm to 1.0 mm isotropic) and diffusion MRI experiments by a factor of 4 (1.5 mm to 0.9 mm isotropic).

  15. MRI-negative refractory partial epilepsy: role for diffusion tensor imaging in high field MRI.

    Science.gov (United States)

    Chen, Qin; Lui, Su; Li, Chun-Xiao; Jiang, Li-Jun; Ou-Yang, Luo; Tang, He-Han; Shang, Hui-Fang; Huang, Xiao-Qi; Gong, Qi-Yong; Zhou, Dong

    2008-07-01

    Our aim is to use the high field MR scanner (3T) to verify whether diffusion tensor imaging (DTI) could help in locating the epileptogenic zone in patients with MRI-negative refractory partial epilepsy. Fifteen patients with refractory partial epilepsy who had normal conventional MRI, and 40 healthy volunteers were recruited for the study. DTI was performed on a 3T MR scanner, individual maps of mean diffusivity (MD) and fractional anisotropy (FA) were calculated, and Voxel-Based Analysis (VBA) was performed for individual comparison between patients and controls. Voxel-based analysis revealed significant MD increase in variant regions in 13 patients. The electroclinical seizure localization was concurred to seven patients. No patient exhibited regions of significant decreased MD. Regions of significant reduced FA were observed in five patients, with two of these concurring with electroclinical seizure localization. Two patients had regions of significant increase in FA, which were distinct from electroclinical seizure localization. Our study's results revealed that DTI is a responsive neuroradiologic technique that provides information about the epileptogenic areas in patients with MRI-negative refractory partial epilepsy. This technique may also helpful in pre-surgical evaluation.

  16. Imaging of postthalamic visual fiber tracts by anisotropic diffusion weighted MRI and diffusion tensor imaging: principles and applications

    International Nuclear Information System (INIS)

    Reinges, Marcus H.T.; Schoth, Felix; Coenen, Volker A.; Krings, Timo

    2004-01-01

    Diffusion weighted MRI offers the possibility to study the course of the cerebral white matter tracts. In the present manuscript, the basics, the technique and the limitations of diffusion tensor imaging and anisotropic diffusion weighted MRI are presented and their applications in various neurological and neurosurgical diseases are discussed with special emphasis on the visual system. A special focus is laid on the combination of fiber tract imaging, anatomical imaging and functional MRI for presurgical planning and intraoperative neuronavigation of lesions near the visual system

  17. Regularized spherical polar fourier diffusion MRI with optimal dictionary learning.

    Science.gov (United States)

    Cheng, Jian; Jiang, Tianzi; Deriche, Rachid; Shen, Dinggang; Yap, Pew-Thian

    2013-01-01

    Compressed Sensing (CS) takes advantage of signal sparsity or compressibility and allows superb signal reconstruction from relatively few measurements. Based on CS theory, a suitable dictionary for sparse representation of the signal is required. In diffusion MRI (dMRI), CS methods proposed for reconstruction of diffusion-weighted signal and the Ensemble Average Propagator (EAP) utilize two kinds of Dictionary Learning (DL) methods: 1) Discrete Representation DL (DR-DL), and 2) Continuous Representation DL (CR-DL). DR-DL is susceptible to numerical inaccuracy owing to interpolation and regridding errors in a discretized q-space. In this paper, we propose a novel CR-DL approach, called Dictionary Learning - Spherical Polar Fourier Imaging (DL-SPFI) for effective compressed-sensing reconstruction of the q-space diffusion-weighted signal and the EAP. In DL-SPFI, a dictionary that sparsifies the signal is learned from the space of continuous Gaussian diffusion signals. The learned dictionary is then adaptively applied to different voxels using a weighted LASSO framework for robust signal reconstruction. Compared with the start-of-the-art CR-DL and DR-DL methods proposed by Merlet et al. and Bilgic et al., respectively, our work offers the following advantages. First, the learned dictionary is proved to be optimal for Gaussian diffusion signals. Second, to our knowledge, this is the first work to learn a voxel-adaptive dictionary. The importance of the adaptive dictionary in EAP reconstruction will be demonstrated theoretically and empirically. Third, optimization in DL-SPFI is only performed in a small subspace resided by the SPF coefficients, as opposed to the q-space approach utilized by Merlet et al. We experimentally evaluated DL-SPFI with respect to L1-norm regularized SPFI (L1-SPFI), which uses the original SPF basis, and the DR-DL method proposed by Bilgic et al. The experiment results on synthetic and real data indicate that the learned dictionary produces

  18. Imaging brain microstructure with diffusion MRI: practicality and applications.

    Science.gov (United States)

    Alexander, Daniel C; Dyrby, Tim B; Nilsson, Markus; Zhang, Hui

    2017-11-29

    This article gives an overview of microstructure imaging of the brain with diffusion MRI and reviews the state of the art. The microstructure-imaging paradigm aims to estimate and map microscopic properties of tissue using a model that links these properties to the voxel scale MR signal. Imaging techniques of this type are just starting to make the transition from the technical research domain to wide application in biomedical studies. We focus here on the practicalities of both implementing such techniques and using them in applications. Specifically, the article summarizes the relevant aspects of brain microanatomy and the range of diffusion-weighted MR measurements that provide sensitivity to them. It then reviews the evolution of mathematical and computational models that relate the diffusion MR signal to brain tissue microstructure, as well as the expanding areas of application. Next we focus on practicalities of designing a working microstructure imaging technique: model selection, experiment design, parameter estimation, validation, and the pipeline of development of this class of technique. The article concludes with some future perspectives on opportunities in this topic and expectations on how the field will evolve in the short-to-medium term. Copyright © 2017 John Wiley & Sons, Ltd.

  19. Flow, diffusion, and rate processes

    International Nuclear Information System (INIS)

    Sieniutycz, S.; Salamon, P.

    1992-01-01

    This volume contains recent results obtained for the nonequilibrium thermodynamics of transport and rate processes are reviewed. Kinetic equations, conservation laws, and transport coefficients are obtained for multicomponent mixtures. Thermodynamic principles are used in the design of experiments predicting heat and mass transport coefficients. Highly nonstationary conditions are analyzed in the context of transient heat transfer, nonlocal diffusion in stress fields and thermohydrodynamic oscillatory instabilities. Unification of the dynamics of chemical systems with other sorts of processes (e.g. mechanical) is given. Thermodynamics of reacting surfaces is developed. Admissible reaction paths are studied and a consistency of chemical kinetics with thermodynamics is shown. Oscillatory reactions are analyzed in a unifying approach showing explosive, conservation or damped behavior. A comprehensive review of transport processes in electrolytes and membranes is given. Applications of thermodynamics to thermoelectric systems and ionized gas (plasma) systems are reviewed

  20. Additional file 2: Figure S1. of Alterations in the inferior longitudinal fasciculus in autism and associations with visual processing: a diffusion-weighted MRI study

    OpenAIRE

    Boets, Bart; Eylen, Lien Van; Sitek, Kevin; Moors, Pieter; Noens, Ilse; Steyaert, Jean; Sunaert, Stefan; Wagemans, Johan

    2018-01-01

    Scatter plots displaying the association between individual differences in FA in right ILF (depicted on the X axis) and individual differences in quantitative ASD characteristics and visual processing measures (depicted on the Y axis). First row: Associations with (square root transformed) scores on the SRS questionnaire, the SRS Social and Communication subscale, the SRS RRBI subscale, and the RBS-R questionnaire. Second row: Associations with reaction time on the Fragmented Object Outlines ...

  1. Linear Invariant Tensor Interpolation Applied to Cardiac Diffusion Tensor MRI

    Science.gov (United States)

    Gahm, Jin Kyu; Wisniewski, Nicholas; Kindlmann, Gordon; Kung, Geoffrey L.; Klug, William S.; Garfinkel, Alan; Ennis, Daniel B.

    2015-01-01

    Purpose Various methods exist for interpolating diffusion tensor fields, but none of them linearly interpolate tensor shape attributes. Linear interpolation is expected not to introduce spurious changes in tensor shape. Methods Herein we define a new linear invariant (LI) tensor interpolation method that linearly interpolates components of tensor shape (tensor invariants) and recapitulates the interpolated tensor from the linearly interpolated tensor invariants and the eigenvectors of a linearly interpolated tensor. The LI tensor interpolation method is compared to the Euclidean (EU), affine-invariant Riemannian (AI), log-Euclidean (LE) and geodesic-loxodrome (GL) interpolation methods using both a synthetic tensor field and three experimentally measured cardiac DT-MRI datasets. Results EU, AI, and LE introduce significant microstructural bias, which can be avoided through the use of GL or LI. Conclusion GL introduces the least microstructural bias, but LI tensor interpolation performs very similarly and at substantially reduced computational cost. PMID:23286085

  2. 3D structure tensor analysis of light microscopy data for validating diffusion MRI.

    Science.gov (United States)

    Khan, Ahmad Raza; Cornea, Anda; Leigland, Lindsey A; Kohama, Steven G; Jespersen, Sune Nørhøj; Kroenke, Christopher D

    2015-05-01

    Diffusion magnetic resonance imaging (d-MRI) is a powerful non-invasive and non-destructive technique for characterizing brain tissue on the microscopic scale. However, the lack of validation of d-MRI by independent experimental means poses an obstacle to accurate interpretation of data acquired using this method. Recently, structure tensor analysis has been applied to light microscopy images, and this technique holds promise to be a powerful validation strategy for d-MRI. Advantages of this approach include its similarity to d-MRI in terms of averaging the effects of a large number of cellular structures, and its simplicity, which enables it to be implemented in a high-throughput manner. However, a drawback of previous implementations of this technique arises from it being restricted to 2D. As a result, structure tensor analyses have been limited to tissue sectioned in a direction orthogonal to the direction of interest. Here we describe the analytical framework for extending structure tensor analysis to 3D, and utilize the results to analyze serial image "stacks" acquired with confocal microscopy of rhesus macaque hippocampal tissue. Implementation of 3D structure tensor procedures requires removal of sources of anisotropy introduced in tissue preparation and confocal imaging. This is accomplished with image processing steps to mitigate the effects of anisotropic tissue shrinkage, and the effects of anisotropy in the point spread function (PSF). In order to address the latter confound, we describe procedures for measuring the dependence of PSF anisotropy on distance from the microscope objective within tissue. Prior to microscopy, ex vivo d-MRI measurements performed on the hippocampal tissue revealed three regions of tissue with mutually orthogonal directions of least restricted diffusion that correspond to CA1, alveus and inferior longitudinal fasciculus. We demonstrate the ability of 3D structure tensor analysis to identify structure tensor orientations that

  3. Diffusion-weighted MRI of the transplanted liver

    International Nuclear Information System (INIS)

    Sandrasegaran, K.; Ramaswamy, R.; Ghosh, S.; Tahir, B.; Akisik, F.M.; Saxena, R.; Kwo, P.

    2011-01-01

    Aim: To assess the value of diffusion-weighted imaging (DWI) in evaluating parenchymal disorders following orthotopic liver transplantation (OLT). Materials and methods: This institutional review board-approved, retrospective study measured the hepatic apparent diffusion coefficients (ADC) in patients following OLT. Those with vascular complications or within 3 months of OLT were excluded. A single-shot echoplanar sequence with b values of 50, 400 (or 500), and 800 s/mm 2 was performed. Liver biopsy specimens [performed with a median of 17 days after magnetic resonance imaging (MRI)] were recorded for the presence and severity of parenchymal disorders, such as acute cellular rejection, and recurrence of fibrosis in all patients, and the recurrence of viral hepatitis in patients with hepatitis C. ADC values were measured blinded to histology in 41 patients (33 males) who had 56 MRI scans. Results: There was a significant difference in ADC values associated with a histological abnormality seen on core biopsy [n = 43, mean (SD) ADC of 0.91 (0.15)x10 -3 mm 2 /s] and those associated with no histological abnormality [n = 13, mean (SD) ADC of 1.11 (0.17)x10 -3 mm 2 /s; (p = 0.003)]. ADC values did not predict any of the individual parenchymal disorders on logistic regression analysis. When the ADC value was -3 mm 2 /s, there was a sensitivity and specificity of 85% and 72%, respectively, in predicting a parenchymal disorder (area under ROC curve = 0.84; 95% CI 0.72 to 0.92). Conclusion: ADC measurements may help in deciding which patients require core liver biopsy after OLT. However, ADC values are not likely to be reliable in differentiating between the various parenchymal disorders.

  4. Diffusion-weighted MRI of the transplanted liver

    Energy Technology Data Exchange (ETDEWEB)

    Sandrasegaran, K., E-mail: ksandras@iupui.edu [Department of Radiology, Indiana University School of Medicine, Indianapolis, IN (United States); Ramaswamy, R. [Department of Radiology, Indiana University School of Medicine, Indianapolis, IN (United States); Ghosh, S. [Department of Mathematics, Indiana University, IN (United States); Tahir, B.; Akisik, F.M. [Department of Radiology, Indiana University School of Medicine, Indianapolis, IN (United States); Saxena, R. [Department of Pathology, Indiana University School of Medicine, Indianapolis, IN (United States); Kwo, P. [Department of Medicine, Indiana University School of Medicine, Indianapolis, IN (United States)

    2011-09-15

    Aim: To assess the value of diffusion-weighted imaging (DWI) in evaluating parenchymal disorders following orthotopic liver transplantation (OLT). Materials and methods: This institutional review board-approved, retrospective study measured the hepatic apparent diffusion coefficients (ADC) in patients following OLT. Those with vascular complications or within 3 months of OLT were excluded. A single-shot echoplanar sequence with b values of 50, 400 (or 500), and 800 s/mm{sup 2} was performed. Liver biopsy specimens [performed with a median of 17 days after magnetic resonance imaging (MRI)] were recorded for the presence and severity of parenchymal disorders, such as acute cellular rejection, and recurrence of fibrosis in all patients, and the recurrence of viral hepatitis in patients with hepatitis C. ADC values were measured blinded to histology in 41 patients (33 males) who had 56 MRI scans. Results: There was a significant difference in ADC values associated with a histological abnormality seen on core biopsy [n = 43, mean (SD) ADC of 0.91 (0.15)x10{sup -3} mm{sup 2}/s] and those associated with no histological abnormality [n = 13, mean (SD) ADC of 1.11 (0.17)x10{sup -3} mm{sup 2}/s; (p = 0.003)]. ADC values did not predict any of the individual parenchymal disorders on logistic regression analysis. When the ADC value was <0.99x10{sup -3} mm{sup 2}/s, there was a sensitivity and specificity of 85% and 72%, respectively, in predicting a parenchymal disorder (area under ROC curve = 0.84; 95% CI 0.72 to 0.92). Conclusion: ADC measurements may help in deciding which patients require core liver biopsy after OLT. However, ADC values are not likely to be reliable in differentiating between the various parenchymal disorders.

  5. Strong Stationary Duality for Diffusion Processes

    OpenAIRE

    Fill, James Allen; Lyzinski, Vince

    2014-01-01

    We develop the theory of strong stationary duality for diffusion processes on compact intervals. We analytically derive the generator and boundary behavior of the dual process and recover a central tenet of the classical Markov chain theory in the diffusion setting by linking the separation distance in the primal diffusion to the absorption time in the dual diffusion. We also exhibit our strong stationary dual as the natural limiting process of the strong stationary dual sequence of a well ch...

  6. Diffusion-weighted MRI of lymphoma: prognostic utility and implications for PET/MRI?

    Energy Technology Data Exchange (ETDEWEB)

    Punwani, Shonit; Taylor, Stuart A.; Halligan, Steve [University College London, Centre for Medical Imaging, London (United Kingdom); University College London Hospital, Department of Radiology, London (United Kingdom); Saad, Ziauddin Z.; Groves, Ashley [University College London Hospital, Institute of Nuclear Medicine, London (United Kingdom); Bainbridge, Alan [University College London Hospital, Department of Medical Physics and Bioengineering, London (United Kingdom); Daw, Stephen; Shankar, Ananth [University College London Hospital, Department of Paediatrics, London (United Kingdom); Humphries, Paul D. [University College London Hospital, Department of Radiology, London (United Kingdom); Great Ormond Street Hospital, Department of Radiology, London (United Kingdom)

    2013-03-15

    With the recent introduction of PET/MRI, we investigated whether diffusion-weighted imaging (DWI) can complement PET for predicting local treatment response in Hodgkin lymphoma. This retrospective study included 39 patients selected from a hospital database with a histological diagnosis of Hodgkin lymphoma undergoing whole-body MRI (supplemented by DWI) and PET/CT before and after two cycles of vincristine, etoposide, prednisolone and doxorubicin (OEPA). The pretreatment volume, MRI apparent diffusion coefficient (ADC) and PET maximum standardized uptake value (SUV{sub max}) of the largest nodal mass were determined quantitatively for evaluation of the local response following two cycles of OEPA. Quantitative pretreatment imaging biomarkers (disease volume, ADC, SUV{sub max}) were compared between sites with an adequate and those with an inadequate response using Fisher's exact test and Mann Whitney statistics. Multivariate models predictive of an inadequate response based on demographic/clinical features, pretreatment disease volume and SUV{sub max} without (model 1) and with (model 2) the addition of ADC were derived and crossvalidated. The ROC area under curve (AUC) was calculated for both models using the full dataset (training) and the crossvalidation (test) data. Sites with an adequate response had a significantly lower median pretreatment ADC (1.0 x 10{sup -3}mm{sup 2}s{sup -1}) than those with an inadequate response (1.26 x 10{sup -3}mm{sup 2}s{sup -1}; p < 0.01). There were no significant differences in patient demographic/clinical parameters, pretreatment SUV{sub max} or pretreatment nodal volume between sites with inadequate and adequate response. The ROC-AUCs for prediction of an inadequate response for the training and test data for model 1 were 0.90 and 0.53, and for model 2 were 0.84 and 0.71, respectively. DWI complements PET for prediction of site-specific interim response to chemotherapy. (orig.)

  7. Analytical performance bounds for multi-tensor diffusion-MRI.

    Science.gov (United States)

    Ahmed Sid, Farid; Abed-Meraim, Karim; Harba, Rachid; Oulebsir-Boumghar, Fatima

    2017-02-01

    To examine the effects of MR acquisition parameters on brain white matter fiber orientation estimation and parameter of clinical interest in crossing fiber areas based on the Multi-Tensor Model (MTM). We compute the Cramér-Rao Bound (CRB) for the MTM and the parameter of clinical interest such as the Fractional Anisotropy (FA) and the dominant fiber orientations, assuming that the diffusion MRI data are recorded by a multi-coil, multi-shell acquisition system. Considering the sum-of-squares method for the reconstructed magnitude image, we introduce an approximate closed-form formula for Fisher Information Matrix that has the simplicity and easy interpretation advantages. In addition, we propose to generalize the FA and the mean diffusivity to the multi-tensor model. We show the application of the CRB to reduce the scan time while preserving a good estimation precision. We provide results showing how the increase of the number of acquisition coils compensates the decrease of the number of diffusion gradient directions. We analyze the impact of the b-value and the Signal-to-Noise Ratio (SNR). The analysis shows that the estimation error variance decreases with a quadratic rate with the SNR, and that the optimum b-values are not unique but depend on the target parameter, the context, and eventually the target cost function. In this study we highlight the importance of choosing the appropriate acquisition parameters especially when dealing with crossing fiber areas. We also provide a methodology for the optimal tuning of these parameters using the CRB. Copyright © 2016 Elsevier Inc. All rights reserved.

  8. Diffusion in Solids Fundamentals, Methods, Materials, Diffusion-Controlled Processes

    CERN Document Server

    Mehrer, Helmut

    2007-01-01

    Diffusion is a vital topic in solid-state physics and chemistry, physical metallurgy and materials science. Diffusion processes are ubiquitous in solids at elevated temperatures. A thorough understanding of diffusion in materials is crucial for materials development and engineering. This book first gives an account of the central aspects of diffusion in solids, for which the necessary background is a course in solid state physics. It then provides easy access to important information about diffuson in metals, alloys, semiconductors, ion-conducting materials, glasses and nanomaterials. Several diffusion-controlled phenomena, including ionic conduction, grain-boundary and dislocation pipe diffusion, are considered as well. Graduate students in solid-state physics, physical metallurgy, materials science, physical and inorganic chemistry or geophysics will benefit from this book as will physicists, chemists, metallurgists, materials engineers in academic and industrial research laboratories.

  9. Diffusion-weighted (DW) MRI in lung cancers. ADC test-retest repeatability

    Energy Technology Data Exchange (ETDEWEB)

    Weller, Alex; Papoutsaki, Marianthi Vasiliki; Blackledge, Matthew; DeSouza, Nandita M. [Institute of Cancer Research and Royal Marsden NHS Foundation Trust, CRUK Cancer Imaging Centre, Surrey (United Kingdom); Waterton, John C. [University of Manchester, Manchester (United Kingdom); Chiti, Arturo [Humanitas University, Milan (Italy); Stroobants, Sigrid [Universiteit Antwerpen, Antwerpen (Belgium); Kuijer, Joost [Vrije Universiteit Medisch Centrum, Amsterdam (Netherlands); Morgan, Veronica [Royal Marsden NHS Foundation Trust, Department of Medicine, London (United Kingdom)

    2017-11-15

    To determine the test-retest repeatability of Apparent Diffusion Coefficient (ADC) measurements across institutions and MRI vendors, plus investigate the effect of post-processing methodology on measurement precision. Thirty malignant lung lesions >2 cm in size (23 patients) were scanned on two occasions, using echo-planar-Diffusion-Weighted (DW)-MRI to derive whole-tumour ADC (b = 100, 500 and 800 s/mm{sup -2}). Scanning was performed at 4 institutions (3 MRI vendors). Whole-tumour volumes-of-interest were copied from first visit onto second visit images and from one post-processing platform to an open-source platform, to assess ADC repeatability and cross-platform reproducibility. Whole-tumour ADC values ranged from 0.66-1.94x10{sup -3} mm{sup 2}s{sup -1} (mean = 1.14). Within-patient coefficient-of-variation (wCV) was 7.1% (95% CI 5.7-9.6%), limits-of-agreement (LoA) -18.0 to 21.9%. Lesions >3 cm had improved repeatability: wCV 3.9% (95% CI 2.9-5.9%); and LoA -10.2 to 11.4%. Variability for lesions <3 cm was 2.46 times higher. ADC reproducibility across different post-processing platforms was excellent: Pearson's R{sup 2} = 0.99; CoV 2.8% (95% CI 2.3-3.4%); and LoA -7.4 to 8.0%. A free-breathing DW-MRI protocol for imaging malignant lung tumours achieved satisfactory within-patient repeatability and was robust to changes in post-processing software, justifying its use in multi-centre trials. For response evaluation in individual patients, a change in ADC >21.9% will reflect treatment-related change. (orig.)

  10. Whole-body MRI, dynamic contrast-enhanced MRI, and diffusion-weighted imaging for the staging of multiple myeloma

    Energy Technology Data Exchange (ETDEWEB)

    Dutoit, Julie C.; Verstraete, Koenraad L. [Ghent University Hospital, Department of Radiology, Ghent (Belgium)

    2017-06-15

    Magnetic resonance imaging (MRI) is the most sensitive imaging technique for the detection of bone marrow infiltration, and has therefore recently been included in the new diagnostic myeloma criteria, as proposed by the International Myeloma Working Group. Nevertheless, conventional MRI only provides anatomical information and is therefore only of limited use in the response assessment of patients with multiple myeloma. The additional information from functional MRI techniques, such as diffusion-weighted imaging and dynamic contrast-enhanced MRI, can improve the detection rate of bone marrow infiltration and the assessment of response. This can further enhance the sensitivity and specificity of MRI in the staging of multiple myeloma patients. This article provides an overview of the technical aspects of conventional and functional MRI techniques with practical recommendations. It reviews the diagnostic performance, prognostic value, and role in therapy assessment in multiple myeloma and its precursor stages. (orig.)

  11. On some applications of diffusion processes for image processing

    International Nuclear Information System (INIS)

    Morfu, S.

    2009-01-01

    We propose a new algorithm inspired by the properties of diffusion processes for image filtering. We show that purely nonlinear diffusion processes ruled by Fisher equation allows contrast enhancement and noise filtering, but involves a blurry image. By contrast, anisotropic diffusion, described by Perona and Malik algorithm, allows noise filtering and preserves the edges. We show that combining the properties of anisotropic diffusion with those of nonlinear diffusion provides a better processing tool which enables noise filtering, contrast enhancement and edge preserving.

  12. Elastography and diffusion-weighted MRI in patients with rectal cancer

    DEFF Research Database (Denmark)

    Rafaelsen, Søren Rafael; Vagn-Hansen, Chris Aksel; Sørensen, Torben

    2015-01-01

    -weighted coefficient (ADC). The purpose of the present study was to compare quantitative elastography based on ultrasound shear wave measurements with MRI ADC. METHODS: We prospectively examined 52 patients with histopathologically proven rectal cancer. The mean age was 67 years (range 42-90 years). Males: 39, females...... a correlation between tissue elasticity and diffusion in rectal cancer.......OBJECTIVE: The current literature has described the usefulness of elastography and diffusion-weighted MRI in patients with cancer, but to the best of our knowledge so far none of them has compared the two new methods. The tumour cell density is related to the MRI-measured apparent diffusion...

  13. Delineation of early brain development from fetuses to infants with diffusion MRI and beyond.

    Science.gov (United States)

    Ouyang, Minhui; Dubois, Jessica; Yu, Qinlin; Mukherjee, Pratik; Huang, Hao

    2018-04-12

    Dynamic macrostructural and microstructural changes take place from the mid-fetal stage to 2 years after birth. Delineating brain structural changes during this early developmental period provides new insights into the complicated processes of both typical brain development and the pathological mechanisms underlying various psychiatric and neurological disorders including autism, attention deficit hyperactivity disorder and schizophrenia. Decades of histological studies have identified strong spatial and functional gradients of maturation in human brain gray and white matter. The recent improvements in magnetic resonance imaging (MRI) techniques, especially diffusion MRI (dMRI), relaxometry imaging, and magnetization transfer imaging (MTI) have provided unprecedented opportunities to non-invasively quantify and map the early developmental changes at whole brain and regional levels. Here, we review the recent advances in understanding early brain structural development during the second half of gestation and the first two postnatal years using modern MR techniques. Specifically, we review studies that delineate the emergence and microstructural maturation of white matter tracts, as well as dynamic mapping of inhomogeneous cortical microstructural organization unique to fetuses and infants. These imaging studies converge into maturational curves of MRI measurements that are distinctive across different white matter tracts and cortical regions. Furthermore, contemporary models offering biophysical interpretations of the dMRI-derived measurements are illustrated to infer the underlying microstructural changes. Collectively, this review summarizes findings that contribute to charting spatiotemporally heterogeneous gray and white matter structural development, offering MRI-based biomarkers of typical brain development and setting the stage for understanding aberrant brain development in neurodevelopmental disorders. Copyright © 2018. Published by Elsevier Inc.

  14. In vivo high-resolution 7 Tesla MRI shows early and diffuse cortical alterations in CADASIL.

    Science.gov (United States)

    De Guio, François; Reyes, Sonia; Vignaud, Alexandre; Duering, Marco; Ropele, Stefan; Duchesnay, Edouard; Chabriat, Hugues; Jouvent, Eric

    2014-01-01

    Recent data suggest that early symptoms may be related to cortex alterations in CADASIL (Cerebral Autosomal-Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy), a monogenic model of cerebral small vessel disease (SVD). The aim of this study was to investigate cortical alterations using both high-resolution T2* acquisitions obtained with 7 Tesla MRI and structural T1 images with 3 Tesla MRI in CADASIL patients with no or only mild symptomatology (modified Rankin's scale ≤1 and Mini Mental State Examination (MMSE) ≥24). Complete reconstructions of the cortex using 7 Tesla T2* acquisitions with 0.7 mm isotropic resolution were obtained in 11 patients (52.1±13.2 years, 36% male) and 24 controls (54.8±11.0 years, 42% male). Seven Tesla T2* within the cortex and cortical thickness and morphology obtained from 3 Tesla images were compared between CADASIL and control subjects using general linear models. MMSE, brain volume, cortical thickness and global sulcal morphology did not differ between groups. By contrast, T2* measured by 7 Tesla MRI was significantly increased in frontal, parietal, occipital and cingulate cortices in patients after correction for multiple testing. These changes were not related to white matter lesions, lacunes or microhemorrhages in patients having no brain atrophy compared to controls. Seven Tesla MRI, by contrast to state of the art post-processing of 3 Tesla acquisitions, shows diffuse T2* alterations within the cortical mantle in CADASIL whose origin remains to be determined.

  15. Model of diffusers / permeators for hydrogen processing

    International Nuclear Information System (INIS)

    Jacobs, W. D.; Hang, T.

    2008-01-01

    Palladium-silver (Pd-Ag) diffusers are mainstays of hydrogen processing. Diffusers separate hydrogen from inert species such as nitrogen, argon or helium. The tubing becomes permeable to hydrogen when heated to more than 250 C and a differential pressure is created across the membrane. The hydrogen diffuses better at higher temperatures. Experimental or experiential results have been the basis for determining or predicting a diffuser's performance. However, the process can be mathematically modeled, and comparison to experimental or other operating data can be utilized to improve the fit of the model. A reliable model-based diffuser system design is the goal which will have impacts on tritium and hydrogen processing. A computer model has been developed to solve the differential equations for diffusion given the operating boundary conditions. The model was compared to operating data for a low pressure diffuser system. The modeling approach and the results are presented in this paper. (authors)

  16. Diffusion processes and memory effects

    International Nuclear Information System (INIS)

    Mokshin, Anatolii V; Yulmetyev, Renat M; Haenggi, Peter

    2005-01-01

    We report the results of the numerical estimation of statistical memory effects in diffusion for two various systems: Lennard-Jones fluids and the model of the Brownian particle in a one-dimensional harmonic lattice. We have found the relation between the diffusion coefficient and the non-Markovity parameter, which is linear for the Lennard-Jones systems in liquid state. The relation between the memory measure and the excess entropy is also discussed here

  17. Model-free and analytical EAP reconstruction via spherical polar Fourier diffusion MRI.

    Science.gov (United States)

    Cheng, Jian; Ghosh, Aurobrata; Jiang, Tianzi; Deriche, Rachid

    2010-01-01

    How to estimate the diffusion Ensemble Average Propagator (EAP) from the DWI signals in q-space is an open problem in diffusion MRI field. Many methods were proposed to estimate the Orientation Distribution Function (ODF) that is used to describe the fiber direction. However, ODF is just one of the features of the EAP. Compared with ODF, EAP has the full information about the diffusion process which reflects the complex tissue micro-structure. Diffusion Orientation Transform (DOT) and Diffusion Spectrum Imaging (DSI) are two important methods to estimate the EAP from the signal. However, DOT is based on mono-exponential assumption and DSI needs a lot of samplings and very large b values. In this paper, we propose Spherical Polar Fourier Imaging (SPFI), a novel model-free fast robust analytical EAP reconstruction method, which almost does not need any assumption of data and does not need too many samplings. SPFI naturally combines the DWI signals with different b-values. It is an analytical linear transformation from the q-space signal to the EAP profile represented by Spherical Harmonics (SH). We validated the proposed methods in synthetic data, phantom data and real data. It works well in all experiments, especially for the data with low SNR, low anisotropy, and non-exponential decay.

  18. Nonrigid Registration of Prostate Diffusion-Weighted MRI

    Directory of Open Access Journals (Sweden)

    Lei Hao

    2017-01-01

    Full Text Available Motion and deformation are common in prostate diffusion-weighted magnetic resonance imaging (DWI during acquisition. These misalignments lead to errors in estimating an apparent diffusion coefficient (ADC map fitted with DWI. To address this problem, we propose an image registration algorithm to align the prostate DWI and improve ADC map. First, we apply affine transformation to DWI to correct intraslice motions. Then, nonrigid registration based on free-form deformation (FFD is used to compensate for intraimage deformations. To evaluate the influence of the proposed algorithm on ADC values, we perform statistical experiments in three schemes: no processing of the DWI, with the affine transform approach, and with FFD. The experimental results show that our proposed algorithm can correct the misalignment of prostate DWI and decrease the artifacts of ROI in the ADC maps. These ADC maps thus obtain sharper contours of lesions, which are helpful for improving the diagnosis and clinical staging of prostate cancer.

  19. Acquisition, estimation, and interpretation of diffusion- and relaxation-based cerebral MRI contrasts

    NARCIS (Netherlands)

    Rudrapatna, U.S.

    2013-01-01

    From the past few years, Magnetic Resonance Imaging has significantly enhanced our understanding of brain structure and function. In particular, developments in Diffusion MRI are providing unique contrast mechanisms heretofore unavailable from other imaging modalities. Although predominantly used

  20. Diffuse axonal injury at ultra-high field MRI.

    Directory of Open Access Journals (Sweden)

    Christoph Moenninghoff

    Full Text Available Diffuse axonal injury (DAI is a specific type of traumatic brain injury caused by shearing forces leading to widespread tearing of axons and small vessels. Traumatic microbleeds (TMBs are regarded as a radiological marker for DAI. This study aims to compare DAI-associated TMBs at 3 Tesla (T and 7 T susceptibility weighted imaging (SWI to evaluate possible diagnostic benefits of ultra-high field (UHF MRI.10 study participants (4 male, 6 female, age range 20-74 years with known DAI were included. All MR exams were performed with a 3 T MR system (Magnetom Skyra and a 7 T MR research system (Magnetom 7 T, Siemens AG, Healthcare Sector, Erlangen, Germany each in combination with a 32-channel-receive coil. The average time interval between trauma and imaging was 22 months. Location and count of TMBs were independently evaluated by two neuroradiologists on 3 T and 7 T SWI images with similar and additionally increased spatial resolution at 7 T. Inter- and intraobserver reliability was assessed using the interclass correlation coefficient (ICC. Count and diameter of TMB were evaluated with Wilcoxon signed rank test.Susceptibility weighted imaging revealed a total of 485 TMBs (range 1-190, median 25 at 3 T, 584 TMBs (plus 20%, range 1-262, median 30.5 at 7 T with similar spatial resolution, and 684 TMBs (plus 41%, range 1-288, median 39.5 at 7 T with 10-times higher spatial resolution. Hemorrhagic DAI appeared significantly larger at 7 T compared to 3 T (p = 0.005. Inter- and intraobserver correlation regarding the counted TMB was high and almost equal 3 T and 7 T.7 T SWI improves the depiction of small hemorrhagic DAI compared to 3 T and may be supplementary to lower field strengths for diagnostic in inconclusive or medicolegal cases.

  1. Longitudinal diffusion MRI for treatment response assessment: Preliminary experience using an MRI-guided tri-cobalt 60 radiotherapy system.

    Science.gov (United States)

    Yang, Yingli; Cao, Minsong; Sheng, Ke; Gao, Yu; Chen, Allen; Kamrava, Mitch; Lee, Percy; Agazaryan, Nzhde; Lamb, James; Thomas, David; Low, Daniel; Hu, Peng

    2016-03-01

    To demonstrate the preliminary feasibility of a longitudinal diffusion magnetic resonance imaging (MRI) strategy for assessing patient response to radiotherapy at 0.35 T using an MRI-guided radiotherapy system (ViewRay). Six patients (three head and neck cancer, three sarcoma) who underwent fractionated radiotherapy were enrolled in this study. A 2D multislice spin echo single-shot echo planar imaging diffusion pulse sequence was implemented on the ViewRay system and tested in phantom studies. The same pulse sequence was used to acquire longitudinal diffusion data (every 2-5 fractions) on the six patients throughout the entire course of radiotherapy. The reproducibility of the apparent diffusion coefficient (ADC) measurements was assessed using reference regions and the temporal variations of the tumor ADC values were evaluated. In diffusion phantom studies, the ADC values measured on the ViewRay system matched well with reference ADC values with ViewRay MRI. Larger patient cohort studies are warranted to correlate the longitudinal diffusion measurements to patient outcomes. Such an approach may enable response-guided adaptive radiotherapy.

  2. Post-processing of structural MRI for individualized diagnostics

    Science.gov (United States)

    Bender, Benjamin; Focke, Niels K.

    2015-01-01

    Currently, a relevant proportion of all histopathologically proven focal cortical dysplasia (FCD) escape visual detection; this shows the need for additional improvements in analyzing MRI data. A positive MRI is still the strongest prognostic factor for postoperative freedom of seizures. Among several post-processing methods voxel-based morphometry (VBM) of T1- and T2-weighted sequences and T2 relaxometry are routinely applied in pre-surgical diagnostics of cryptogenic epilepsy in epilepsy centers. VBM is superior to conventional visual analysis with 9-15% more identified epileptogenic foci, while T2 relaxometry has its main application in (mesial) temporal lobe epilepsy. Further methods such as surface-based morphometry (SBM) or diffusion tensor imaging are promising but there is a lack of current studies comparing their individual diagnostic value. Post-processing methods represent an important addition to conventional visual analysis but need to be interpreted with expertise and experience so that they should be apprehended as a complementary tool within the context of the multi-modal evaluation of epilepsy patients. This review will give an overview of existing post-processing methods of structural MRI and outline their clinical relevance in detection of epileptogenic structural changes. PMID:25853079

  3. Benign and malignant skull-involved lesions: discriminative value of conventional CT and MRI combined with diffusion-weighted MRI.

    Science.gov (United States)

    Tu, Zhanhai; Xiao, Zebin; Zheng, Yingyan; Huang, Hongjie; Yang, Libin; Cao, Dairong

    2018-01-01

    Background Little is known about the value of computed tomography (CT) and magnetic resonance imaging (MRI) combined with diffusion-weighted imaging (DWI) in distinguishing malignant from benign skull-involved lesions. Purpose To evaluate the discriminative value of DWI combined with conventional CT and MRI for differentiating between benign and malignant skull-involved lesions. Material and Methods CT and MRI findings of 58 patients with pathologically proven skull-involved lesions (43 benign and 15 malignant) were retrospectively reviewed. Conventional CT and MRI characteristics and apparent diffusion coefficient (ADC) value of the two groups were evaluated and compared. Multivariate logistic regression and receiver operating characteristic (ROC) curve analyses were performed to assess the differential performance of each parameter separately and together. Results The presence of cortical defects or break-through and ill-defined margins were associated with malignant skull-involved lesions (both P benign and malignant skull-involved lesions. Conclusion The combination of CT, MRI, and DWI can help to differentiate malignant from benign skull-involved lesions. CT + MRI + DWI offers optimal sensitivity, while DWI offers optimal specificity.

  4. Conventional and Diffusion-Weighted MRI in the Evaluation of Methanol Poisoning. A case report

    International Nuclear Information System (INIS)

    Server, A.; Nakstad, P.Hj.; Dullerud, R.; Haakonsen, M.; Hovda, K.E.; Jacobsen, D.

    2003-01-01

    Cerebral lesions were studied in 2 methanol-poisoned patients using conventional magnetic resonance imaging (MRI). In 1 patient, diffusion-weighted MRI (DWI) was also performed. In this patient, conventional MRI showed symmetrical, bilateral increased signal in the lentiform nuclei, involving predominantly putamina, but also extending into the corona radiata, centrum semiovale and subcortical white matter. DWI showed decreased diffusion, which most probably reflects cytotoxic edema. In the other patient, fluid attenuated-inversion recovery (FLAIR) and T2-weighted images showed hyperintensity in the putamina, characteristic of post-necrotic changes

  5. Diffusion processes in dyed detectors

    International Nuclear Information System (INIS)

    Lferde, M.; Seidel, J.-L.; Monnin, M.

    1982-01-01

    In order to get a better understanding of the dyed and fluorescent track detectors, the diffusion speed of the swelling agent, the sensitization molecules and the dye have been measured under various conditions. It is shown that the sensitization affects the entire detector while dyeing is restricted to the upper and lower layers of the detector. By combining the optimal values of the reactions parameters a higher contrast and sensitivity may be achieved. (author)

  6. Cortical fibers orientation mapping using in-vivo whole brain 7 T diffusion MRI

    NARCIS (Netherlands)

    Gulban, Omer F; De Martino, Federico; Vu, An T; Yacoub, Essa; Uğurbil, Kamil; Lenglet, Christophe

    Diffusion MRI of the cortical gray matter is challenging because the micro-environment probed by water molecules is much more complex than within the white matter. High spatial and angular resolutions are therefore necessary to uncover anisotropic diffusion patterns and laminar structures, which

  7. Diffusion tensor tractography as a supplementary tool to conventional MRI for evaluating patients with myelopathy

    Directory of Open Access Journals (Sweden)

    Amal Amin A. El Maati

    2014-12-01

    Conclusion: Diffusion tensor imaging is a reliable method for the evaluation of the diffusion properties of normal and compressed spinal cords. Furthermore, this technique can be used as an important supplementary tool to conventional MRI for the quantification of fiber damage in spinal cord compression, thus has the potential to be of great utility for treatment planning and follow up.

  8. Variability of non-Gaussian diffusion MRI and intravoxel incoherent motion (IVIM) measurements in the breast.

    Science.gov (United States)

    Iima, Mami; Kataoka, Masako; Kanao, Shotaro; Kawai, Makiko; Onishi, Natsuko; Koyasu, Sho; Murata, Katsutoshi; Ohashi, Akane; Sakaguchi, Rena; Togashi, Kaori

    2018-01-01

    We prospectively examined the variability of non-Gaussian diffusion magnetic resonance imaging (MRI) and intravoxel incoherent motion (IVIM) measurements with different numbers of b-values and excitations in normal breast tissue and breast lesions. Thirteen volunteers and fourteen patients with breast lesions (seven malignant, eight benign; one patient had bilateral lesions) were recruited in this prospective study (approved by the Internal Review Board). Diffusion-weighted MRI was performed with 16 b-values (0-2500 s/mm2 with one number of excitations [NEX]) and five b-values (0-2500 s/mm2, 3 NEX), using a 3T breast MRI. Intravoxel incoherent motion (flowing blood volume fraction [fIVIM] and pseudodiffusion coefficient [D*]) and non-Gaussian diffusion (theoretical apparent diffusion coefficient [ADC] at b value of 0 sec/mm2 [ADC0] and kurtosis [K]) parameters were estimated from IVIM and Kurtosis models using 16 b-values, and synthetic apparent diffusion coefficient (sADC) values were obtained from two key b-values. The variabilities between and within subjects and between different diffusion acquisition methods were estimated. There were no statistical differences in ADC0, K, or sADC values between the different b-values or NEX. A good agreement of diffusion parameters was observed between 16 b-values (one NEX), five b-values (one NEX), and five b-values (three NEX) in normal breast tissue or breast lesions. Insufficient agreement was observed for IVIM parameters. There were no statistical differences in the non-Gaussian diffusion MRI estimated values obtained from a different number of b-values or excitations in normal breast tissue or breast lesions. These data suggest that a limited MRI protocol using a few b-values might be relevant in a clinical setting for the estimation of non-Gaussian diffusion MRI parameters in normal breast tissue and breast lesions.

  9. Pseudotumours in chronic kidney disease: Can diffusion-weighted MRI rule out malignancy

    International Nuclear Information System (INIS)

    Goyal, Ankur; Sharma, Raju; Bhalla, Ashu S.; Gamanagatti, Shivanand; Seth, Amlesh

    2013-01-01

    Highlights: •Conventional non-contrast MRI is unable to distinguish CKD pseudotumors from RCCs. •Pseudotumours in a background of CKD do not show restricted diffusion. •CKD pseudotumours demonstrate high ADC values whereas RCCs show restricted diffusion. •DW-MRI is reliable in ruling out malignancy incase of pseudotumours found in chronic kidney disease. •DW-MRI may obviate contrast administration and/or tissue sampling in renal pseudotumours and prevent inadvertent surgeries. -- Abstract: Objectives: To evaluate whether diffusion-weighted MRI (DW-MRI) can distinguish pseudotumours in chronic kidney disease (CKD pseudotumours) from renal-cell-carcinomas (RCCs) (with or without CKD) and whether it offers additional benefit over conventional MRI. Methods: One-hundred patients underwent MDCT, MRI and DW-MRI (at b-values of 0 and 500 s/mm 2 ) for evaluation of focal renal lesions. Of these, 20 patients with 40 CKD pseudotumours and 36 patients with 40 RCCs were retrospectively analyzed. T1-weighted, T2-weighted, diffusion-weighted images were evaluated, apparent-diffusion-coefficient (ADC) values were compared and receiver-operating-characteristic (ROC) curves were drawn to establish cut-off ADC-values. Results: 92.5% of CKD pseudotumours remained indeterminate after conventional MRI. On DW-MRI, none of them showed restricted diffusion and thus malignancy could be ruled out in 100% of the lesions. In contrast, all the solid RCCs showed diffusion restriction. Mean ADC-value for CKD pseudotumours was significantly higher than RCCs and surrounding diseased parenchyma [2.50 vs 1.56 (×10 −3 mm 2 /s) (P < 0.0001) and 2.05 (×10 −3 mm 2 /s) (P = 0.0001) respectively]. ROC analysis for differentiating CKD pseudotumours and RCC yielded high sensitivity (91.7%) and specificity (100%) for cut-off ADC-value of 2.04 (×10 −3 mm 2 /s). Conclusions: CKD pseudotumors usually remain indeterminate on conventional non-contrast MRI. DW-MRI can distinguish CKD pseudotumors

  10. Pseudotumours in chronic kidney disease: Can diffusion-weighted MRI rule out malignancy

    Energy Technology Data Exchange (ETDEWEB)

    Goyal, Ankur, E-mail: ankurgoyalaiims@gmail.com [Department of Radiodiagnosis, All India Institute of Medical Sciences (A.I.I.M.S.), New Delhi (India); Sharma, Raju, E-mail: raju152@yahoo.com [Department of Radiodiagnosis, All India Institute of Medical Sciences (A.I.I.M.S.), New Delhi (India); Bhalla, Ashu S., E-mail: ashubhalla1@yahoo.com [Department of Radiodiagnosis, All India Institute of Medical Sciences (A.I.I.M.S.), New Delhi (India); Gamanagatti, Shivanand, E-mail: shiv223@rediffmail.com [Department of Radiodiagnosis, All India Institute of Medical Sciences (A.I.I.M.S.), New Delhi (India); Seth, Amlesh, E-mail: amlesh.seth@gmail.com [Department of Urology, All India Institute of Medical Sciences (A.I.I.M.S.), New Delhi (India)

    2013-11-01

    Highlights: •Conventional non-contrast MRI is unable to distinguish CKD pseudotumors from RCCs. •Pseudotumours in a background of CKD do not show restricted diffusion. •CKD pseudotumours demonstrate high ADC values whereas RCCs show restricted diffusion. •DW-MRI is reliable in ruling out malignancy incase of pseudotumours found in chronic kidney disease. •DW-MRI may obviate contrast administration and/or tissue sampling in renal pseudotumours and prevent inadvertent surgeries. -- Abstract: Objectives: To evaluate whether diffusion-weighted MRI (DW-MRI) can distinguish pseudotumours in chronic kidney disease (CKD pseudotumours) from renal-cell-carcinomas (RCCs) (with or without CKD) and whether it offers additional benefit over conventional MRI. Methods: One-hundred patients underwent MDCT, MRI and DW-MRI (at b-values of 0 and 500 s/mm{sup 2}) for evaluation of focal renal lesions. Of these, 20 patients with 40 CKD pseudotumours and 36 patients with 40 RCCs were retrospectively analyzed. T1-weighted, T2-weighted, diffusion-weighted images were evaluated, apparent-diffusion-coefficient (ADC) values were compared and receiver-operating-characteristic (ROC) curves were drawn to establish cut-off ADC-values. Results: 92.5% of CKD pseudotumours remained indeterminate after conventional MRI. On DW-MRI, none of them showed restricted diffusion and thus malignancy could be ruled out in 100% of the lesions. In contrast, all the solid RCCs showed diffusion restriction. Mean ADC-value for CKD pseudotumours was significantly higher than RCCs and surrounding diseased parenchyma [2.50 vs 1.56 (×10{sup −3} mm{sup 2}/s) (P < 0.0001) and 2.05 (×10{sup −3} mm{sup 2}/s) (P = 0.0001) respectively]. ROC analysis for differentiating CKD pseudotumours and RCC yielded high sensitivity (91.7%) and specificity (100%) for cut-off ADC-value of 2.04 (×10{sup −3} mm{sup 2}/s). Conclusions: CKD pseudotumors usually remain indeterminate on conventional non-contrast MRI. DW-MRI

  11. Stability of Gradient Field Corrections for Quantitative Diffusion MRI

    OpenAIRE

    Rogers, Baxter P.; Blaber, Justin; Welch, E. Brian; Ding, Zhaohua; Anderson, Adam W.; Landman, Bennett A.

    2017-01-01

    In magnetic resonance diffusion imaging, gradient nonlinearity causes significant bias in the estimation of quantitative diffusion parameters such as diffusivity, anisotropy, and diffusion direction in areas away from the magnet isocenter. This bias can be substantially reduced if the scanner- and coil-specific gradient field nonlinearities are known. Using a set of field map calibration scans on a large (29 cm diameter) phantom combined with a solid harmonic approximation of the gradient fie...

  12. Symmetries and modelling functions for diffusion processes

    International Nuclear Information System (INIS)

    Nikitin, A G; Spichak, S V; Vedula, Yu S; Naumovets, A G

    2009-01-01

    A constructive approach to the theory of diffusion processes is proposed, which is based on application of both symmetry analysis and the method of modelling functions. An algorithm for construction of the modelling functions is suggested. This algorithm is based on the error function expansion (ERFEX) of experimental concentration profiles. The high-accuracy analytical description of the profiles provided by ERFEX approximation allows a convenient extraction of the concentration dependence of diffusivity from experimental data and prediction of the diffusion process. Our analysis is exemplified by its employment in experimental results obtained for surface diffusion of lithium on the molybdenum (1 1 2) surface precovered with dysprosium. The ERFEX approximation can be directly extended to many other diffusion systems.

  13. Probing white-matter microstructure with higher-order diffusion tensors and susceptibility tensor MRI

    Science.gov (United States)

    Liu, Chunlei; Murphy, Nicole E.; Li, Wei

    2012-01-01

    Diffusion MRI has become an invaluable tool for studying white matter microstructure and brain connectivity. The emergence of quantitative susceptibility mapping and susceptibility tensor imaging (STI) has provided another unique tool for assessing the structure of white matter. In the highly ordered white matter structure, diffusion MRI measures hindered water mobility induced by various tissue and cell membranes, while susceptibility sensitizes to the molecular composition and axonal arrangement. Integrating these two methods may produce new insights into the complex physiology of white matter. In this study, we investigated the relationship between diffusion and magnetic susceptibility in the white matter. Experiments were conducted on phantoms and human brains in vivo. Diffusion properties were quantified with the diffusion tensor model and also with the higher order tensor model based on the cumulant expansion. Frequency shift and susceptibility tensor were measured with quantitative susceptibility mapping and susceptibility tensor imaging. These diffusion and susceptibility quantities were compared and correlated in regions of single fiber bundles and regions of multiple fiber orientations. Relationships were established with similarities and differences identified. It is believed that diffusion MRI and susceptibility MRI provide complementary information of the microstructure of white matter. Together, they allow a more complete assessment of healthy and diseased brains. PMID:23507987

  14. In Vivo Evaluation of the Visual Pathway in Streptozotocin-Induced Diabetes by Diffusion Tensor MRI and Contrast Enhanced MRI.

    Directory of Open Access Journals (Sweden)

    Swarupa Kancherla

    Full Text Available Visual function has been shown to deteriorate prior to the onset of retinopathy in some diabetic patients and experimental animal models. This suggests the involvement of the brain's visual system in the early stages of diabetes. In this study, we tested this hypothesis by examining the integrity of the visual pathway in a diabetic rat model using in vivo multi-modal magnetic resonance imaging (MRI. Ten-week-old Sprague-Dawley rats were divided into an experimental diabetic group by intraperitoneal injection of 65 mg/kg streptozotocin in 0.01 M citric acid, and a sham control group by intraperitoneal injection of citric acid only. One month later, diffusion tensor MRI (DTI was performed to examine the white matter integrity in the brain, followed by chromium-enhanced MRI of retinal integrity and manganese-enhanced MRI of anterograde manganese transport along the visual pathway. Prior to MRI experiments, the streptozotocin-induced diabetic rats showed significantly smaller weight gain and higher blood glucose level than the control rats. DTI revealed significantly lower fractional anisotropy and higher radial diffusivity in the prechiasmatic optic nerve of the diabetic rats compared to the control rats. No apparent difference was observed in the axial diffusivity of the optic nerve, the chromium enhancement in the retina, or the manganese enhancement in the lateral geniculate nucleus and superior colliculus between groups. Our results suggest that streptozotocin-induced diabetes leads to early injury in the optic nerve when no substantial change in retinal integrity or anterograde transport along the visual pathways was observed in MRI using contrast agent enhancement. DTI may be a useful tool for detecting and monitoring early pathophysiological changes in the visual system of experimental diabetes non-invasively.

  15. In vivo high-resolution 7 Tesla MRI shows early and diffuse cortical alterations in CADASIL.

    Directory of Open Access Journals (Sweden)

    François De Guio

    Full Text Available Recent data suggest that early symptoms may be related to cortex alterations in CADASIL (Cerebral Autosomal-Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy, a monogenic model of cerebral small vessel disease (SVD. The aim of this study was to investigate cortical alterations using both high-resolution T2* acquisitions obtained with 7 Tesla MRI and structural T1 images with 3 Tesla MRI in CADASIL patients with no or only mild symptomatology (modified Rankin's scale ≤1 and Mini Mental State Examination (MMSE ≥24.Complete reconstructions of the cortex using 7 Tesla T2* acquisitions with 0.7 mm isotropic resolution were obtained in 11 patients (52.1±13.2 years, 36% male and 24 controls (54.8±11.0 years, 42% male. Seven Tesla T2* within the cortex and cortical thickness and morphology obtained from 3 Tesla images were compared between CADASIL and control subjects using general linear models.MMSE, brain volume, cortical thickness and global sulcal morphology did not differ between groups. By contrast, T2* measured by 7 Tesla MRI was significantly increased in frontal, parietal, occipital and cingulate cortices in patients after correction for multiple testing. These changes were not related to white matter lesions, lacunes or microhemorrhages in patients having no brain atrophy compared to controls.Seven Tesla MRI, by contrast to state of the art post-processing of 3 Tesla acquisitions, shows diffuse T2* alterations within the cortical mantle in CADASIL whose origin remains to be determined.

  16. A biomimetic tumor tissue phantom for validating diffusion-weighted MRI measurements.

    Science.gov (United States)

    McHugh, Damien J; Zhou, Feng-Lei; Wimpenny, Ian; Poologasundarampillai, Gowsihan; Naish, Josephine H; Hubbard Cristinacce, Penny L; Parker, Geoffrey J M

    2018-07-01

    To develop a biomimetic tumor tissue phantom which more closely reflects water diffusion in biological tissue than previously used phantoms, and to evaluate the stability of the phantom and its potential as a tool for validating diffusion-weighted (DW) MRI measurements. Coaxial-electrospraying was used to generate micron-sized hollow polymer spheres, which mimic cells. The bulk structure was immersed in water, providing a DW-MRI phantom whose apparent diffusion coefficient (ADC) and microstructural properties were evaluated over a period of 10 months. Independent characterization of the phantom's microstructure was performed using scanning electron microscopy (SEM). The repeatability of the construction process was investigated by generating a second phantom, which underwent high resolution synchrotron-CT as well as SEM and MR scans. ADC values were stable (coefficients of variation (CoVs) < 5%), and varied with diffusion time, with average values of 1.44 ± 0.03 µm 2 /ms (Δ = 12 ms) and 1.20 ± 0.05 µm 2 /ms (Δ = 45 ms). Microstructural parameters showed greater variability (CoVs up to 13%), with evidence of bias in sphere size estimates. Similar trends were observed in the second phantom. A novel biomimetic phantom has been developed and shown to be stable over 10 months. It is envisaged that such phantoms will be used for further investigation of microstructural models relevant to characterizing tumor tissue, and may also find application in evaluating acquisition protocols and comparing DW-MRI-derived biomarkers obtained from different scanners at different sites. Magn Reson Med 80:147-158, 2018. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is

  17. Diffusion properties of conventional and calcium-sensitive MRI contrast agents in the rat cerebral cortex.

    Science.gov (United States)

    Hagberg, Gisela E; Mamedov, Ilgar; Power, Anthony; Beyerlein, Michael; Merkle, Hellmut; Kiselev, Valerij G; Dhingra, Kirti; Kubìček, Vojtĕch; Angelovski, Goran; Logothetis, Nikos K

    2014-01-01

    Calcium-sensitive MRI contrast agents can only yield quantitative results if the agent concentration in the tissue is known. The agent concentration could be determined by diffusion modeling, if relevant parameters were available. We have established an MRI-based method capable of determining diffusion properties of conventional and calcium-sensitive agents. Simulations and experiments demonstrate that the method is applicable both for conventional contrast agents with a fixed relaxivity value and for calcium-sensitive contrast agents. The full pharmacokinetic time-course of gadolinium concentration estimates was observed by MRI before, during and after intracerebral administration of the agent, and the effective diffusion coefficient D* was determined by voxel-wise fitting of the solution to the diffusion equation. The method yielded whole brain coverage with a high spatial and temporal sampling. The use of two types of MRI sequences for sampling of the diffusion time courses was investigated: Look-Locker-based quantitative T(1) mapping, and T(1) -weighted MRI. The observation times of the proposed MRI method is long (up to 20 h) and consequently the diffusion distances covered are also long (2-4 mm). Despite this difference, the D* values in vivo were in agreement with previous findings using optical measurement techniques, based on observation times of a few minutes. The effective diffusion coefficient determined for the calcium-sensitive contrast agents may be used to determine local tissue concentrations and to design infusion protocols that maintain the agent concentration at a steady state, thereby enabling quantitative sensing of the local calcium concentration. Copyright © 2014 John Wiley & Sons, Ltd.

  18. Differentiation of thyroid nodules using diffusion-weighted MRI

    African Journals Online (AJOL)

    Lamiss Mohamed Abd el Aziz

    2014-10-19

    Oct 19, 2014 ... technique for brain tumors. DWI is sensitive to changes in the microstructural organization of tissue that may affect water diffusion. It has been used to evaluate head and neck tumors.9–11 The Apparent Diffusion Coefficient (ADC) value is a quantitative parameter for distinguishing malignant tumors from ...

  19. Diffusion and perfusion MRI for the localisation of epileptogenic foci in drug-resistant epilepsy

    International Nuclear Information System (INIS)

    Heiniger, P.; El-Koussy, M.; Kiefer, C.; Oswald, H.; Schroth, G.; Schindler, K.; Donati, F.; Loevblad, K.O.; Wissmeyer, M.; Mariani, L.; Weder, B.

    2002-01-01

    Drug-resistant epilepsy is an important clinical challenge, both diagnostically and therapeutically. More and more surgical options are being considered, but precise presurgical assessment is necessary. We prospectively studied eight patients with drug-resistant epilepsy, who underwent clinical examination, single photon emission computed tomography (SPECT) and interictal MRI, including diffusion- and perfusion-weighted echoplanar sequences. Lesions suspected on SPECT of being epileptogenic showed mild hypoperfusion, while the diffusion-weighted MRI (DWI) revealed increased apparent diffusion coefficients relative to the other side. However, these abnormalities were not visible on the corresponding maps. We showed that DWI and perfusion-weighted MRI could be used confirm the characteristics and site of an epileptogenic area in patients with drug-resistant epilepsy. (orig.)

  20. Focal status epilepticus: follow-up by perfusion- and diffusion MRI

    International Nuclear Information System (INIS)

    El-Koussy, M.; Loevblad, K.O.; Kiefer, C.; Schroth, G.; Mathis, J.; Stepper, F.

    2002-01-01

    Diffusion-weighted MRI demonstrated bright right temporoparietal cortex, right hippocampus, and left cerebellum in a 63-year-old female suffering a focal convulsive status epilepticus. Hyperperfusion was noted in the right temporoparietal region. Two days later, a tendency to normalization of most of the diffusion and perfusion changes was noted, apart from the right hippocampus which became brighter on diffusion- and T2-weighted images. On the tenth day the apparent diffusion coefficient was slightly elevated, getting brighter on T2-weighted images with suspected mild post-contrast enhancement. We postulate that the discharging right hippocampus suffered cytotoxic edema, which later progressed to cell damage. (orig.)

  1. Focal status epilepticus: follow-up by perfusion- and diffusion MRI

    Energy Technology Data Exchange (ETDEWEB)

    El-Koussy, M; Loevblad, K O; Kiefer, C; Schroth, G [Department of Neuroradiology, University of Bern, Inselspital (Switzerland); Mathis, J; Stepper, F [Department of Neurology, University of Bern, Inselspital (Switzerland)

    2002-03-01

    Diffusion-weighted MRI demonstrated bright right temporoparietal cortex, right hippocampus, and left cerebellum in a 63-year-old female suffering a focal convulsive status epilepticus. Hyperperfusion was noted in the right temporoparietal region. Two days later, a tendency to normalization of most of the diffusion and perfusion changes was noted, apart from the right hippocampus which became brighter on diffusion- and T2-weighted images. On the tenth day the apparent diffusion coefficient was slightly elevated, getting brighter on T2-weighted images with suspected mild post-contrast enhancement. We postulate that the discharging right hippocampus suffered cytotoxic edema, which later progressed to cell damage. (orig.)

  2. Detecting causality in policy diffusion processes

    OpenAIRE

    Grabow, Carsten; Macinko, James; Silver, Diana; Porfiri, Maurizio

    2016-01-01

    A universal question in network science entails learning about the topology of interaction from collective dynamics. Here, we address this question by examining diffusion of laws across US states. We propose two complementary techniques to unravel determinants of this diffusion process: information-theoretic union transfer entropy and event synchronization. In order to systematically investigate their performance on law activity data, we establish a new stochastic model to generate synthetic ...

  3. Statistical Inference for Partially Observed Diffusion Processes

    DEFF Research Database (Denmark)

    Jensen, Anders Christian

    This thesis is concerned with parameter estimation for multivariate diffusion models. It gives a short introduction to diffusion models, and related mathematical concepts. we then introduce the method of prediction-based estimating functions and describe in detail the application for a two......-Uhlenbeck process, while chapter eight describes the detials of an R-package that was developed in relations to the application of the estimationprocedure of chapters five and six....

  4. Diffusion-weighted MRI of the liver—Interpretative pearls and pitfalls

    International Nuclear Information System (INIS)

    Culverwell, A.D.; Sheridan, M.B.; Guthrie, J.A.; Scarsbrook, A.F.

    2013-01-01

    Diffusion-weighted magnetic resonance imaging (DW MRI) is an established technique in neuroradiology and more recently has emerged as a useful adjunct to various oncological applications of MRI. It has an expanding role in the evaluation of liver lesions, offers higher detection rates for small lesions, and can increase confidence in differentiating between benign and malignant lesions. Other applications include assessment of tumour response to therapy, differentiating tumour from bland thrombus, and assessment of liver fibrosis. DW sequences can be performed on most modern MRI machines with relative ease, in a short time period and without the need for contrast medium. DW MRI can be of value in the detection and characterization of hepatic lesions but there are pitfalls, which can potentially cause interpretative difficulty. This article will review the rationale for DW MRI in liver imaging, demonstrate the clinical utility of the technique in a spectrum of hepatic diseases, and illustrate key interpretative pearls and pitfalls

  5. Parametric dictionary learning for modeling EAP and ODF in diffusion MRI.

    Science.gov (United States)

    Merlet, Sylvain; Caruyer, Emmanuel; Deriche, Rachid

    2012-01-01

    In this work, we propose an original and efficient approach to exploit the ability of Compressed Sensing (CS) to recover diffusion MRI (dMRI) signals from a limited number of samples while efficiently recovering important diffusion features such as the ensemble average propagator (EAP) and the orientation distribution function (ODF). Some attempts to sparsely represent the diffusion signal have already been performed. However and contrarly to what has been presented in CS dMRI, in this work we propose and advocate the use of a well adapted learned dictionary and show that it leads to a sparser signal estimation as well as to an efficient reconstruction of very important diffusion features. We first propose to learn and design a sparse and parametric dictionary from a set of training diffusion data. Then, we propose a framework to analytically estimate in closed form two important diffusion features: the EAP and the ODF. Various experiments on synthetic, phantom and human brain data have been carried out and promising results with reduced number of atoms have been obtained on diffusion signal reconstruction, thus illustrating the added value of our method over state-of-the-art SHORE and SPF based approaches.

  6. Maximum likelihood estimation for integrated diffusion processes

    DEFF Research Database (Denmark)

    Baltazar-Larios, Fernando; Sørensen, Michael

    We propose a method for obtaining maximum likelihood estimates of parameters in diffusion models when the data is a discrete time sample of the integral of the process, while no direct observations of the process itself are available. The data are, moreover, assumed to be contaminated...... EM-algorithm to obtain maximum likelihood estimates of the parameters in the diffusion model. As part of the algorithm, we use a recent simple method for approximate simulation of diffusion bridges. In simulation studies for the Ornstein-Uhlenbeck process and the CIR process the proposed method works...... by measurement errors. Integrated volatility is an example of this type of observations. Another example is ice-core data on oxygen isotopes used to investigate paleo-temperatures. The data can be viewed as incomplete observations of a model with a tractable likelihood function. Therefore we propose a simulated...

  7. Diffusion weighted MRI in intrahepatic bile duct adenoma arising from the cirrhotic liver

    Energy Technology Data Exchange (ETDEWEB)

    An, Chansik [Research Institute of Radiological Science, Severance Hospital, Yonsei University College of Medicine, Seoul (Korea, Republic of); Park, Sumi; Choi, Yoon Jung [National Health Insurance Corporation Ilsan Hospital, Goyang (Korea, Republic of)

    2013-10-15

    A 64-year-old male patient with liver cirrhosis underwent a CT study for hepatocellular carcinoma surveillance, which demonstrated a 1.4-cm hypervascular subcapsular tumor in the liver. On gadoxetic acid-enhanced MRI, the tumor showed brisk arterial enhancement and persistent hyperenhancement in the portal phase, but hypointensity in the hepatobiliary phase. On diffusion-weighted MRI, the tumor showed an apparent diffusion coefficient twofold greater than that of the background liver parenchyma, which suggested that the lesion was benign. The histologic diagnosis was intrahepatic bile duct adenoma with alcoholic liver cirrhosis.

  8. Diffusion-weighted MRI in intrahepatic bile duct adenoma arising from the cirrhotic liver.

    Science.gov (United States)

    An, Chansik; Park, Sumi; Choi, Yoon Jung

    2013-01-01

    A 64-year-old male patient with liver cirrhosis underwent a CT study for hepatocellular carcinoma surveillance, which demonstrated a 1.4-cm hypervascular subcapsular tumor in the liver. On gadoxetic acid-enhanced MRI, the tumor showed brisk arterial enhancement and persistent hyperenhancement in the portal phase, but hypointensity in the hepatobiliary phase. On diffusion-weighted MRI, the tumor showed an apparent diffusion coefficient twofold greater than that of the background liver parenchyma, which suggested that the lesion was benign. The histologic diagnosis was intrahepatic bile duct adenoma with alcoholic liver cirrhosis.

  9. Diffusion Weighted MRI as a predictive tool for effect of radiotherapy in locally advanced cervical cancer

    DEFF Research Database (Denmark)

    Haack, Søren; Tanderup, Kari; Fokdal, Lars

    Diffusion weighted MRI has shown great potential in diagnostic cancer imaging and may also have value for monitoring tumor response during radiotherapy. Patients with advanced cervical cancer are treated with external beam radiotherapy followed by brachytherapy. This study evaluates the value of DW......-MRI for predicting outcome of patients with advanced cervical cancer at time of brachytherapy. Volume of hyper-intensity on highly diffusion sensitive images and resulting ADC value for treatment responders and non-responders is compared. The change of ADC and volume of hyper-intensity over time of BT is also...

  10. Diffusion-weighted MRI in the diagnosis of intracranial hematomas

    OpenAIRE

    Şanlı, Davut; Ünal, Özkan; Bora, Aydın; Beyazal, Mehmet; Yavuz, Alpaslan; Avcu, Serhat

    2013-01-01

    Abstract. To determinate the diagnostic value of diffusion-weighted MR imaging (DWI) in intracerebral hematomas, epidural hematomas, subdural hematomas, and subarachnoid hemorrhage, and to assess the contribution of diffusion signal characteristics in the differentiation of hematoma stages. In this prospective study, consecutive 67 patients (range: 3-89 years), 35 (18 men 17 women) with intracerebral hematoma, 18 (10 men 8 women) with subdural hematoma, 2 (1 man 1 woman) with epidural hematom...

  11. Anisotropic Diffusion based Brain MRI Segmentation and 3D Reconstruction

    OpenAIRE

    M. Arfan Jaffar; Sultan Zia; Ghaznafar Latif; AnwarM. Mirza; Irfan Mehmood; Naveed Ejaz; Sung Wook Baik

    2012-01-01

    In medical field visualization of the organs is very imperative for accurate diagnosis and treatment of any disease. Brain tumor diagnosis and surgery also required impressive 3D visualization of the brain to the radiologist. Detection and 3D reconstruction of brain tumors from MRI is a computationally time consuming and error-prone task. Proposed system detects and presents a 3D visualization model of the brain and tumor inside which greatly helps the radiologist to effectively diagnose and ...

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

    Science.gov (United States)

    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. © 2015 Elsevier B.V. All rights reserved.

  13. Diffusion-weighted MRI in Crohn's disease: Current status and recommendations

    OpenAIRE

    Dohan, A.; Taylor, S.; Hoeffel, C.; Barret, M.; Allez, M.; Dautry, R.; Zappa, M.; Savoye-Collet, C.; Dray, X.; Boudiaf, M.; Reinhold, C.; Soyer, P.

    2016-01-01

    Over the past years, technological improvements and refinements in magnetic resonance imaging (MRI) hardware have made high-quality diffusion-weighted imaging (DWI) routinely possible for the bowel. DWI is promising for the detection and characterization of lesions in Crohn's disease (CD) and has been advocated as an alternative to intravenous gadolinium-based contrast agents. Furthermore, quantification using the apparent diffusion coefficient may have value as a biomarker of CD activity and...

  14. Anisotropic Diffusion based Brain MRI Segmentation and 3D Reconstruction

    Directory of Open Access Journals (Sweden)

    M. Arfan Jaffar

    2012-06-01

    Full Text Available In medical field visualization of the organs is very imperative for accurate diagnosis and treatment of any disease. Brain tumor diagnosis and surgery also required impressive 3D visualization of the brain to the radiologist. Detection and 3D reconstruction of brain tumors from MRI is a computationally time consuming and error-prone task. Proposed system detects and presents a 3D visualization model of the brain and tumor inside which greatly helps the radiologist to effectively diagnose and analyze the brain tumor. We proposed a multi-phase segmentation and visualization technique which overcomes the many problems of 3D volume segmentation methods like lake of fine details. In this system segmentation is done in three different phases which reduces the error chances. The system finds contours for skull, brain and tumor. These contours are stacked over and two novel methods are used to find the 3D visualization models. The results of these techniques, particularly of interpolation based, are impressive. Proposed system is tested against publically available data set [41] and MRI datasets available from MRI aamp; CT center Rawalpindi, Pakistan [42].

  15. On the Viability of Diffusion MRI-Based Microstructural Biomarkers in Ischemic Stroke

    Directory of Open Access Journals (Sweden)

    Ilaria Boscolo Galazzo

    2018-02-01

    Full Text Available Recent tract-based analyses provided evidence for the exploitability of 3D-SHORE microstructural descriptors derived from diffusion MRI (dMRI in revealing white matter (WM plasticity. In this work, we focused on the main open issues left: (1 the comparative analysis with respect to classical tensor-derived indices, i.e., Fractional Anisotropy (FA and Mean Diffusivity (MD; and (2 the ability to detect plasticity processes in gray matter (GM. Although signal modeling in GM is still largely unexplored, we investigated their sensibility to stroke-induced microstructural modifications occurring in the contralateral hemisphere. A more complete picture could provide hints for investigating the interplay of GM and WM modulations. Ten stroke patients and ten age/gender-matched healthy controls were enrolled in the study and underwent diffusion spectrum imaging (DSI. Acquisitions at three and two time points (tp were performed on patients and controls, respectively. For all subjects and acquisitions, FA and MD were computed along with 3D-SHORE-based indices [Generalized Fractional Anisotropy (GFA, Propagator Anisotropy (PA, Return To the Axis Probability (RTAP, Return To the Plane Probability (RTPP, and Mean Square Displacement (MSD]. Tract-based analysis involving the cortical, subcortical and transcallosal motor networks and region-based analysis in GM were successively performed, focusing on the contralateral hemisphere to the stroke. Reproducibility of all the indices on both WM and GM was quantitatively proved on controls. For tract-based, longitudinal group analyses revealed the highest significant differences across the subcortical and transcallosal networks for all the indices. The optimal regression model for predicting the clinical motor outcome at tp3 included GFA, PA, RTPP, and MSD in the subcortical network in combination with the main clinical information at baseline. Region-based analysis in the contralateral GM highlighted the ability of

  16. Differentiation of prostate cancer lesions in the Transition Zone by diffusion-weighted MRI

    Directory of Open Access Journals (Sweden)

    Jie Bao

    Full Text Available Objective: To differentiate prostate cancer lesions in transition zone by diffusion-weighted-MRI (DW-MRI. Methods: Data from a total of 63 patients who underwent preoperative DWI (b of 0–1000 s/mm2 were prospectively collected and processed by a monoexponential (DWI model and compared with a biexponential (IVIM model for quantitation of apparent diffusion coefficients (ADCs, perfusion fraction f, diffusivity D and pseudo-diffusivity D*. Histogram analyses were performed by outlining entire-tumor regions of interest (ROIs. These parameters (separately and combined in a logistic regression model were used to differentiate lesions depending on histopathological analysis of Magnetic Resonance/transrectal Ultrasound (MR/TRUS fusion-guided biopsy. The diagnostic ability of differentiate the PCa from BHP in TZ was analyzed by ROC regression. Histogram analysis of quantitative parameters and Gleason score were assessed with Spearman correlation. Results: Thirty (30 foci cases of PCa in PZ and 33 (36 foci cases of BPH were confirmed by pathology. Mean ADC, median ADC, 10th percentile ADC, 90th percentile ADC, kurtosis and skewness of ADC and mean D values, median D and 90th percentile D differed significantly between PCa and BHP in TZ. The highest classification accuracy was achieved by the mean ADC (0.841 and mean D (0.809. A logistic regression model based on mean ADC and mean D led to an AUC of 0.873, however, the difference is not significant. There were 7 Gleason 6 areas, 9 Gleason 7 areas, 8 Gleason 8 areas, 5 Gleason 9 areas and 2 Gleason 10 areas detected from the 31 prostate cancer areas, the mean Gleason value was(7.5 ± 1.2. The mean ADC and mean D had correlation with Gleason score(r = −0.522 and r = −0.407 respectively, P < 0.05. Conclusion: The diagnosis efficiency of IVIM parameters was not superior to ADC in the diagnosis of PCa in TZ. Moreover, the combination of mean ADC and mean D did not

  17. Diffusive epidemic process: theory and simulation

    International Nuclear Information System (INIS)

    Maia, Daniel Souza; Dickman, Ronald

    2007-01-01

    We study the continuous absorbing-state phase transition in the one-dimensional diffusive epidemic process via mean-field theory and Monte Carlo simulation. In this model, particles of two species (A and B) hop on a lattice and undergo reactions B → A and A+B → 2B; the total particle number is conserved. We formulate the model as a continuous-time Markov process described by a master equation. A phase transition between the (absorbing) B-free state and an active state is observed as the parameters (reaction and diffusion rates, and total particle density) are varied. Mean-field theory reveals a surprising, nonmonotonic dependence of the critical recovery rate on the diffusion rate of B particles. A computational realization of the process that is faithful to the transition rates defining the model is devised, allowing for direct comparison with theory. Using the quasi-stationary simulation method we determine the order parameter and the survival time in systems of up to 4000 sites. Due to strong finite-size effects, the results converge only for large system sizes. We find no evidence for a discontinuous transition. Our results are consistent with the existence of three distinct universality classes, depending on whether A particles diffusive more rapidly, less rapidly or at the same rate as B particles. We also perform quasi-stationary simulations of the triplet creation model, which yield results consistent with a discontinuous transition at high diffusion rates

  18. Focal Pancreatitis Mimicking Pancreatic Mass: Magnetic Resonance Imaging (MRI)/Magnetic Resonance Cholangiopancreatography (MRCP) Findings Including Diffusion-Weighted MRI

    International Nuclear Information System (INIS)

    Momtahen, A.J.; Balci, N.C.; Alkaade, S.; Akduman, E.I.; Burton, F.R.

    2008-01-01

    Background: Focal pancreatitis (FP) is a confined inflammation that mimics a pancreatic mass. Its imaging diagnosis is important to avoid unnecessary procedures. Purpose: To describe the spectrum of magnetic resonance imaging (MRI)/magnetic resonance cholangiopancreatography (MRCP) and diffusion-weighted MRI (DWI) findings of focal pancreatitis mimicking pancreatic masses. Material and Methods: Findings of MRI/MRCP including DWI with a b value of 0 and 600 s/mm2 in 14 patients with pancreatic masses on MRI were retrospectively reviewed and compared to normal pancreas in 14 patients as a control group. Results: FP revealed hypointense signal intensity (SI) (3/14), hypo- to isointense SI (7/14), or isointense SI (4/14) on T1-weighted images, and hypointense SI (1/14), isointense SI (5/14), iso- to hyperintense SI (7/14), or hyperintense SI (1/14) on T2-weighted images compared to remaining pancreas (RP). MRCP images revealed dilatation of the common bile duct (CBD) and main pancreatic duct (MPD) (5/14), dilatation of the MPD only (3/14), dilatation of the CBD only (3/14), and normal MPD and CBD (3/14). Both FP and RP revealed three types of time-signal intensity curves: 1) rapid rise to a peak, with a rapid decline (FP=2, RP=4), 2) slow rise to a peak, followed by a slow decline (FP=5, RP=4), and 3) slower rise to a peak, with a slow decline or plateau (FP=7, RP=6). Mean apparent diffusion coefficient (ADC) values for FP and RP were 2.09±0.18 and 2.03±0.2x10 -3 mm 2 /s, respectively. ADC values of FP and RP revealed no significant difference. Conclusion: The spectrum of imaging findings of focal pancreatitis on MRI/MRCP including DWI was described. Findings of FP were not distinctive as compared to the remaining pancreas

  19. Rotationally invariant clustering of diffusion MRI data using spherical harmonics

    DEFF Research Database (Denmark)

    Liptrot, Matthew George; Lauze, Francois Bernard

    2016-01-01

    simple features that are invariant to the rotation of the highly orientational diffusion data. This provides a way to directly classify voxels whose diffusion characteristics are similar yet whose primary diffusion orientations differ. Subsequent application of machine-learning to the spherical harmonic...... data as a collection of spherical basis functions. We use the derived coefficients as voxelwise feature vectors for classification. Using a simple Gaussian mixture model, we examined the classification performance for a range of sub-classes (3-20). The results were compared against existing...... classification of DWI data can be performed without the need for a model reconstruction step. This avoids the potential confounds and uncertainty that such models may impose, and has the benefit of being computable directly from the DWI volumes. As such, the method could prove useful in subsequent pre...

  20. Uranium enrichment by the gaseous diffusion process

    International Nuclear Information System (INIS)

    Petit, J.F.

    1977-01-01

    After a brief description of the process and technology (principle, stage constitution, cascade constitution, and description of a plant), the author gives the history of gaseous diffusion and describes the existing facilities. Among the different enrichment processes contemplated in the USA during and after the last world war, gaseous diffusion has been the only one to be developed industrially on a wide scale in the USA, then in the UK, in the USSR and in France. The large existing capacities in the USA provided the country with a good starting base for the development of a light-water nuclear power plant programme, the success of which led to a shortfall in production means. France and the USA, possessing the necessary know-how, have been able to undertake the realization of two industrial programmes: the CIP-CUP programme in the USA and the Eurodif project in France. Current plans still call for the construction of several plants by 1990. Can the gaseous diffusion process meet this challenge. Technically, there is no doubt about it. Economically, this process is mainly characterized by large energy consumption and the necessity to build large plants. This leads to a large investment, at least for the first plant. Other processes have been developed with a view to reducing both energy and capital needs. However, in spite of continuous studies and technological progress, no process has yet proved competitive. Large increments in capacities are still expected to come from gaseous diffusion, and several projects taking into account the improvements in flexibility, automatization, reliability and reduced investment, are analysed in the paper. Combining new facilities with existing plants has already proved to be of great interest. This situation explains why gaseous diffusion is being further investigated and new processes are being studied. (author)

  1. Diffusion-weighted MRI of the prostate at 3.0 T: comparison of endorectal coil (ERC) MRI and phased-array coil (PAC) MRI-The impact of SNR on ADC measurement.

    Science.gov (United States)

    Mazaheri, Yousef; Vargas, H Alberto; Nyman, Gregory; Shukla-Dave, Amita; Akin, Oguz; Hricak, Hedvig

    2013-10-01

    To compare ADC values measured from diffusion-weighted MR (DW-MR) images of the prostate obtained with both endorectal and phased-array coils (ERC+PAC) to those from DW-MRI images obtained with an eight-channel torso phased-array coil (PAC) at 3.0 T. The institutional review board issued a waiver of informed consent for this HIPAA-compliant study. Twenty-five patients with biopsy-proven prostate cancer underwent standard 3-T MRI using 2 different coil arrangements (ERC+PAC and PAC only) in the same session. DW-MRI at five b-values (0, 600, 1000, 1200, and 1500 s/mm(2)) were acquired using both coil arrangements. On b=0 images, signal-to-noise ratios (SNRs) were measured as the ratio of the mean signal from PZ and TZ ROIs to the standard deviation from the mean signal in an artifact-free ROI in the rectum. Matching regions-of-interest (ROIs) were identified in the peripheral zone and transition zone on ERC-MRI and PAC-MRI. For each ROI, mean ADC values for all zero and non-zero b-value combinations were computed. Mean SNR with ERC-MRI at PZ (66.33 ± 27.07) and TZ (32.69 ± 12.52) was 9.27 and 5.52 times higher than with PAC-MRI ((7.32 ± 2.30) and (6.13 ± 1.56), respectively) (PERC-MRI (PERC. To address these requirements, clinical MR systems should have image processing capabilities which incorporate the noise distribution. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

  2. MRI shows thickening and altered diffusion in the median and ulnar nerves in multifocal motor neuropathy

    DEFF Research Database (Denmark)

    Haakma, Wieke; Jongbloed, Bas A.; Froeling, Martijn

    2017-01-01

    Objectives To study disease mechanisms in multifocal motor neuropathy (MMN) with magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) of the median and ulnar nerves. Methods We enrolled ten MMN patients, ten patients with amyotrophic lateral sclerosis (ALS) and ten healthy controls...

  3. Exploring the multiple-hit hypothesis of preterm white matter damage using diffusion MRI

    Directory of Open Access Journals (Sweden)

    Madeleine L. Barnett

    2018-01-01

    Conclusion: This study suggests multiple perinatal risk factors have an independent association with diffuse white matter injury at term equivalent age and exposure to multiple perinatal risk factors exacerbates dMRI defined, clinically significant white matter injury. Our findings support the multiple hit hypothesis for preterm white matter injury.

  4. In vivo reconstruction of lumbar erector spinae architecture using diffusion tensor MRI

    NARCIS (Netherlands)

    Sieben, Judith M.; Van Otten, Ilse; Lataster, Arno; Froeling, Martijn; Nederveen, Aart J.; Strijkers, Gustav J.; Drost, Maarten R.

    2016-01-01

    Study Design: Diffusion tensor magnetic resonance imaging (DTMRI) reconstruction of lumbar erector spinae (ES) compared with cadaver dissection. Objective: The aim of this study was to reconstruct the human lumbar ES from in vivo DT-MRI measurements and to compare the results with literature and

  5. Pediatric and adult MRI atlas of bone marrow. Normal appearances, variants and diffuse disease states

    Energy Technology Data Exchange (ETDEWEB)

    Ilaslan, Hakan; Sundaram, Murali [Cleveland Clinic Lerner College of Medicine, OH (United States); Cleveland Clinic Department of Radiology, OH (United States)

    2016-08-01

    This comprehensive atlas is unique in being devoted to the MRI appearances of bone marrow in the axial and appendicular skeleton of adults and children. Normal MRI findings, including common variants and degenerative changes, are first documented. MRI appearances in the entire spectrum of neoplastic and non-neoplastic infiltrative marrow disorders are then presented, with accompanying explanatory text. Among the conditions considered are multiple myeloma, the acute and chronic leukemias, diffuse metastases, diffuse lymphomas, the anemias, polycythemia vera, myelofibrosis, storage disorders, and infections. Characteristic changes to bone marrow following various forms of treatment are also displayed and discussed. The selected images reflect the use of a variety of sequences and techniques, such as fat suppression, and contrast-enhanced imaging.

  6. On the Averaging of Cardiac Diffusion Tensor MRI Data: The Effect of Distance Function Selection

    Science.gov (United States)

    Giannakidis, Archontis; Melkus, Gerd; Yang, Guang; Gullberg, Grant T.

    2016-01-01

    Diffusion tensor magnetic resonance imaging (DT-MRI) allows a unique insight into the microstructure of highly-directional tissues. The selection of the most proper distance function for the space of diffusion tensors is crucial in enhancing the clinical application of this imaging modality. Both linear and nonlinear metrics have been proposed in the literature over the years. The debate on the most appropriate DT-MRI distance function is still ongoing. In this paper, we presented a framework to compare the Euclidean, affine-invariant Riemannian and log-Euclidean metrics using actual high-resolution DT-MRI rat heart data. We employed temporal averaging at the diffusion tensor level of three consecutive and identically-acquired DT-MRI datasets from each of five rat hearts as a means to rectify the background noise-induced loss of myocyte directional regularity. This procedure is applied here for the first time in the context of tensor distance function selection. When compared with previous studies that used a different concrete application to juxtapose the various DT-MRI distance functions, this work is unique in that it combined the following: (i) Metrics were judged by quantitative –rather than qualitative– criteria, (ii) the comparison tools were non-biased, (iii) a longitudinal comparison operation was used on a same-voxel basis. The statistical analyses of the comparison showed that the three DT-MRI distance functions tend to provide equivalent results. Hence, we came to the conclusion that the tensor manifold for cardiac DT-MRI studies is a curved space of almost zero curvature. The signal to noise ratio dependence of the operations was investigated through simulations. Finally, the “swelling effect” occurrence following Euclidean averaging was found to be too unimportant to be worth consideration. PMID:27754986

  7. On the averaging of cardiac diffusion tensor MRI data: the effect of distance function selection

    Science.gov (United States)

    Giannakidis, Archontis; Melkus, Gerd; Yang, Guang; Gullberg, Grant T.

    2016-11-01

    Diffusion tensor magnetic resonance imaging (DT-MRI) allows a unique insight into the microstructure of highly-directional tissues. The selection of the most proper distance function for the space of diffusion tensors is crucial in enhancing the clinical application of this imaging modality. Both linear and nonlinear metrics have been proposed in the literature over the years. The debate on the most appropriate DT-MRI distance function is still ongoing. In this paper, we presented a framework to compare the Euclidean, affine-invariant Riemannian and log-Euclidean metrics using actual high-resolution DT-MRI rat heart data. We employed temporal averaging at the diffusion tensor level of three consecutive and identically-acquired DT-MRI datasets from each of five rat hearts as a means to rectify the background noise-induced loss of myocyte directional regularity. This procedure is applied here for the first time in the context of tensor distance function selection. When compared with previous studies that used a different concrete application to juxtapose the various DT-MRI distance functions, this work is unique in that it combined the following: (i) metrics were judged by quantitative—rather than qualitative—criteria, (ii) the comparison tools were non-biased, (iii) a longitudinal comparison operation was used on a same-voxel basis. The statistical analyses of the comparison showed that the three DT-MRI distance functions tend to provide equivalent results. Hence, we came to the conclusion that the tensor manifold for cardiac DT-MRI studies is a curved space of almost zero curvature. The signal to noise ratio dependence of the operations was investigated through simulations. Finally, the ‘swelling effect’ occurrence following Euclidean averaging was found to be too unimportant to be worth consideration.

  8. Temporal evolution of ischemic lesions in nonhuman primates: a diffusion and perfusion MRI study.

    Directory of Open Access Journals (Sweden)

    Xiaodong Zhang

    Full Text Available Diffusion-weighted imaging (DWI and perfusion MRI were used to examine the spatiotemporal evolution of stroke lesions in adult macaques with ischemic occlusion.Permanent MCA occlusion was induced with silk sutures through an interventional approach via the femoral artery in adult rhesus monkeys (n = 8, 10-21 years old. The stroke lesions were examined with high-resolution DWI and perfusion MRI, and T2-weighted imaging (T2W on a clinical 3T scanner at 1-6, 48, and 96 hours post occlusion and validated with H&E staining.The stroke infarct evolved via a natural logarithmic pattern with the mean infarct growth rate = 1.38 ± 1.32 ml per logarithmic time scale (hours (n = 7 in the hyperacute phase (1-6 hours. The mean infarct volume after 6 hours post occlusion was 3.6±2.8 ml (n = 7, by DWI and increased to 3.9±2.9 ml (n = 5, by T2W after 48 hours, and to 4.7±2.2ml (n = 3, by T2W after 96 hours post occlusion. The infarct volumes predicted by the natural logarithmic function were correlated significantly with the T2W-derived lesion volumes (n = 5, r = 0.92, p = 0.01 at 48 hours post occlusion. The final infarct volumes derived from T2W were correlated significantly with those from H&E staining (r = 0.999, p < 0.0001, n = 4. In addition, the diffusion-perfusion mismatch was visible generally at 6 hours but nearly diminished at 48 hours post occlusion.The infarct evolution follows a natural logarithmic pattern in the hyperacute phase of stroke. The logarithmic pattern of evolution could last up to 48 hours after stroke onset and may be used to predict the infarct volume growth during the acute phase of ischemic stroke. The nonhuman primate model, MRI protocols, and post data processing strategy may provide an excellent platform for characterizing the evolution of acute stroke lesion in mechanistic studies and therapeutic interventions of stroke disease.

  9. Functional MRI of Language Processing and Recovery

    NARCIS (Netherlands)

    C. Méndez Orellana (Carolina)

    2015-01-01

    markdownabstract__Abstract__ My thesis describe the utility of implementing fMRI to investigate how the language system is reorganized in brain damaged patients. Specifically for aphasia research fMRI allows to show how specific language treatment methods have the potential to enhance language

  10. The Pearson diffusions: A class of statistically tractable diffusion processes

    DEFF Research Database (Denmark)

    Forman, Julie Lyng; Sørensen, Michael

    The Pearson diffusions is a flexible class of diffusions defined by having linear drift and quadratic squared diffusion coefficient. It is demonstrated that for this class explicit statistical inference is feasible. Explicit optimal martingale estimating func- tions are found, and the corresponding...

  11. Fully automated processing of fMRI data in SPM: from MRI scanner to PACS.

    Science.gov (United States)

    Maldjian, Joseph A; Baer, Aaron H; Kraft, Robert A; Laurienti, Paul J; Burdette, Jonathan H

    2009-01-01

    Here we describe the Wake Forest University Pipeline, a fully automated method for the processing of fMRI data using SPM. The method includes fully automated data transfer and archiving from the point of acquisition, real-time batch script generation, distributed grid processing, interface to SPM in MATLAB, error recovery and data provenance, DICOM conversion and PACS insertion. It has been used for automated processing of fMRI experiments, as well as for the clinical implementation of fMRI and spin-tag perfusion imaging. The pipeline requires no manual intervention, and can be extended to any studies requiring offline processing.

  12. Path Integral Formulation of Anomalous Diffusion Processes

    OpenAIRE

    Friedrich, Rudolf; Eule, Stephan

    2011-01-01

    We present the path integral formulation of a broad class of generalized diffusion processes. Employing the path integral we derive exact expressions for the path probability densities and joint probability distributions for the class of processes under consideration. We show that Continuous Time Random Walks (CTRWs) are included in our framework. A closed expression for the path probability distribution of CTRWs is found in terms of their waiting time distribution as the solution of a Dyson ...

  13. Granger-Causality Maps of Diffusion Processes

    Czech Academy of Sciences Publication Activity Database

    Wahl, B.; Feudel, U.; Hlinka, Jaroslav; Wächter, M.; Peinke, J.; Freund, J.A.

    2016-01-01

    Roč. 93, č. 2 16 February (2016), č. článku 022213. ISSN 2470-0045 R&D Projects: GA ČR GA13-23940S; GA MZd(CZ) NV15-29835A Institutional support: RVO:67985807 Keywords : Granger causality * stochastic process * diffusion process * nonlinear dynamical systems Subject RIV: BB - Applied Statistics, Operational Research Impact factor: 2.366, year: 2016

  14. Selection for biopsy of kidney transplant patients by diffusion-weighted MRI

    Energy Technology Data Exchange (ETDEWEB)

    Steiger, Philipp; Barbieri, Sebastiano; Ith, Michael; Thoeny, Harriet C. [Inselspital, Bern University Hospital, University of Bern, Inselspital, Department of Radiology, Neuroradiology, and Nuclear Medicine, Institute of Diagnostic, Pediatric, and Interventional Radiology, Bern (Switzerland); Kruse, Anja [Inselspital, Bern University Hospital, University of Bern, Inselspital, Department of Nephrology and Hypertension, Bern (Switzerland)

    2017-10-15

    To assess retrospectively whether diffusion-weighted magnetic resonance imaging (DW-MRI) allows physicians to determine the severity of histopathologic findings in biopsies of renal allograft patients with deteriorating renal function. Forty consecutive kidney transplant patients underwent DW-MRI and biopsy. Patients were assigned to one group with severe and to another group with normal or mild histopathologic findings. These two groups were compared based on a qualitative DW-MRI assessment (homo-/heterogeneity) and the combination of qualitative and quantitative DW-MRI parameters (ADC, and intravoxel incoherent motion, IVIM, parameters: D, f, D*). Sensitivity, specificity, and accuracy were determined for each parameter. Biopsy findings were severe in 25 patients and normal or mild in 15 patients. Qualitative DW-MRI led to a sensitivity of 44.0% and a specificity of 93.3%. Combined qualitative and quantitative DW-MRI led to an accuracy of 80% for both the minimal ADC (ADCmin) and the minimal perfusion fraction (fmin) with a sensitivity of 84.0% and 92.0% and a specificity of 73.3% and 60.0%, respectively. Combined qualitative and quantitative DW-MRI might allow physicians to determine the severity of histopathologic findings in biopsies of a high number of kidney transplant patients. (orig.)

  15. MGH-USC Human Connectome Project datasets with ultra-high b-value diffusion MRI.

    Science.gov (United States)

    Fan, Qiuyun; Witzel, Thomas; Nummenmaa, Aapo; Van Dijk, Koene R A; Van Horn, John D; Drews, Michelle K; Somerville, Leah H; Sheridan, Margaret A; Santillana, Rosario M; Snyder, Jenna; Hedden, Trey; Shaw, Emily E; Hollinshead, Marisa O; Renvall, Ville; Zanzonico, Roberta; Keil, Boris; Cauley, Stephen; Polimeni, Jonathan R; Tisdall, Dylan; Buckner, Randy L; Wedeen, Van J; Wald, Lawrence L; Toga, Arthur W; Rosen, Bruce R

    2016-01-01

    The MGH-USC CONNECTOM MRI scanner housed at the Massachusetts General Hospital (MGH) is a major hardware innovation of the Human Connectome Project (HCP). The 3T CONNECTOM scanner is capable of producing a magnetic field gradient of up to 300 mT/m strength for in vivo human brain imaging, which greatly shortens the time spent on diffusion encoding, and decreases the signal loss due to T2 decay. To demonstrate the capability of the novel gradient system, data of healthy adult participants were acquired for this MGH-USC Adult Diffusion Dataset (N=35), minimally preprocessed, and shared through the Laboratory of Neuro Imaging Image Data Archive (LONI IDA) and the WU-Minn Connectome Database (ConnectomeDB). Another purpose of sharing the data is to facilitate methodological studies of diffusion MRI (dMRI) analyses utilizing high diffusion contrast, which perhaps is not easily feasible with standard MR gradient system. In addition, acquisition of the MGH-Harvard-USC Lifespan Dataset is currently underway to include 120 healthy participants ranging from 8 to 90 years old, which will also be shared through LONI IDA and ConnectomeDB. Here we describe the efforts of the MGH-USC HCP consortium in acquiring and sharing the ultra-high b-value diffusion MRI data and provide a report on data preprocessing and access. We conclude with a demonstration of the example data, along with results of standard diffusion analyses, including q-ball Orientation Distribution Function (ODF) reconstruction and tractography. Copyright © 2015 Elsevier Inc. All rights reserved.

  16. Unraveling the multiscale structural organization and connectivity of the human brain: the role of diffusion MRI

    Directory of Open Access Journals (Sweden)

    Matteo eBastiani

    2015-06-01

    Full Text Available The structural architecture and the anatomical connectivity of the human brain show different organizational principles at distinct spatial scales. Histological staining and light microscopy techniques have been widely used in classical neuroanatomical studies to unravel brain organization. Using such techniques is a laborious task performed on 2-dimensional histological sections by skilled anatomists possibly aided by semi-automated algorithms. With the recent advent of modern magnetic resonance imaging (MRI contrast mechanisms, cortical layers and columns can now be reliably identified and their structural properties quantified post mortem. These developments are allowing the investigation of neuroanatomical features of the brain at a spatial resolution that could be interfaced with that of histology. Diffusion MRI and tractography techniques, in particular, have been used to probe the architecture of both white and gray matter in three dimensions. Combined with mathematical network analysis, these techniques are increasingly influential in the investigation of the macro-, meso- and microscopic organization of brain connectivity and anatomy, both in vivo and ex vivo. Diffusion MRI-based techniques in combination with histology approaches can therefore support the endeavor of creating multimodal atlases that take into account the different spatial scales or levels on which the brain is organized. The aim of this review is to illustrate and discuss the structural architecture and the anatomical connectivity of the human brain at different spatial scales and how recently developed diffusion MRI techniques can help investigate these.

  17. Diffusion-weighted echo-planar MRI of lacunar infarcts

    International Nuclear Information System (INIS)

    Noguchi, K.; Nagayoshi, T.; Watanabe, N.; Kanazawa, T.; Toyoshima, S.; Morijiri, M.; Shojaku, H.; Shimizu, M.; Seto, H.

    1998-01-01

    We studied 35 patients with lacunar infarcts, using diffusion-weighted echo-planar imaging (DW-EPI) at 1.5 T. The relative apparent diffusion coefficient ratio (ADCR) of each lesion was calculated and lesion conspicuity on DW-EPI was compared to that on images aquired with fast fluid-attenuated inversion recovery and T2-weighted fast spin-echo sequences. Acute small infarcts (within 3 days) were identified with DW-EPI as an area of decreased ADCR (range 0.33-0.87; mean 0.67) and high signal, subacute small infarcts (4-30 days) as a high-signal or isointense areas of decreased or nearly normal ADCR (0.54-0.98; 0.73), and chronic small infarcts (> 30 days) as low- or high-signal areas of nearly normal or increased ADCR (0.97-1.92; 1.32). In three patients, small infarcts of the brain stem in the hyperacute phase (within 6 h) were seen only with DW-EPI. In five patients, fresh small infarcts adjacent to multiple old infarcts could be distinguished only with DW-EPI. (orig.)

  18. Modeling of Reaction Processes Controlled by Diffusion

    International Nuclear Information System (INIS)

    Revelli, Jorge

    2003-01-01

    Stochastic modeling is quite powerful in science and technology.The technics derived from this process have been used with great success in laser theory, biological systems and chemical reactions.Besides, they provide a theoretical framework for the analysis of experimental results on the field of particle's diffusion in ordered and disordered materials.In this work we analyze transport processes in one-dimensional fluctuating media, which are media that change their state in time.This fact induces changes in the movements of the particles giving rise to different phenomena and dynamics that will be described and analyzed in this work.We present some random walk models to describe these fluctuating media.These models include state transitions governed by different dynamical processes.We also analyze the trapping problem in a lattice by means of a simple model which predicts a resonance-like phenomenon.Also we study effective diffusion processes over surfaces due to random walks in the bulk.We consider different boundary conditions and transitions movements.We derive expressions that describe diffusion behaviors constrained to bulk restrictions and the dynamic of the particles.Finally it is important to mention that the theoretical results obtained from the models proposed in this work are compared with Monte Carlo simulations.We find, in general, excellent agreements between the theory and the simulations

  19. On diffusion process generators and scattering theory

    International Nuclear Information System (INIS)

    Demuth, M.

    1980-01-01

    In scattering theory the existence of wave operators is one of the mainly interesting points. For two selfadjoint operators K and H defined in separable Hilbertspaces H tilde and H' tilde, respectively, the usual two space wave operator is defined by Ωsub(+-)(H,J,K) = s-lim esup(itH)Jesup(-itK)Psup(ac), t → +-infinity, if these limits exist. J is the identification operator mapping H tilde into H' tilde. Psup(ac) is the orthogonal projection onto the absolutely continuous subspace of K. The objective is to prove the existence and completeness of the wave operator for K and K+V where K is a diffusion process generator and V a singular perturbation. Because generators of diffusion processes can be obtained by extension of second order differential operators with variable coefficients the result connects hard-core potential problems and wave operator existence for diffusion process generators including scattering theory for second order elliptic differential operators by means of the stochastic process theory and stochastic differential equation solutions. (author)

  20. Relationship between pretreatment FDG-PET and diffusion-weighted MRI biomarkers in diffuse large B-cell lymphoma

    Science.gov (United States)

    de Jong, Antoinette; Kwee, Thomas C; de Klerk, John MH; Adam, Judit A; de Keizer, Bart; Fijnheer, Rob; Kersten, Marie José; Ludwig, Inge; Jauw, Yvonne WS; Zijlstra, Josée M; den Bos, Indra C Pieters - Van; Stoker, Jaap; Hoekstra, Otto S; Nievelstein, Rutger AJ

    2014-01-01

    The purpose of this study was to determine the correlation between the 18F-fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) standardized uptake value (SUV) and the diffusion-weighted magnetic resonance imaging (MRI) apparent diffusion coefficient (ADC) in newly diagnosed diffuse large B-cell lymphoma (DLBCL). Pretreatment FDG-PET and diffusion-weighted MRI of 21 patients with histologically proven DLBCL were prospectively analyzed. In each patient, maximum, mean and peak standardized uptake value (SUV) was measured in the lesion with visually highest FDG uptake and in the largest lesion. Mean ADC (ADCmean, calculated with b-values of 0 and 1000 s/mm2) was measured in the same lesions. Correlations between FDG-PET metrics (SUVmax, SUVmean, SUVpeak) and ADCmean were assessed using Pearson’s correlation coefficients. In the lesions with visually highest FDG uptake, no significant correlations were found between the SUVmax, SUVmean, SUVpeak and the ADCmean (P=0.498, P=0.609 and P=0.595, respectively). In the largest lesions, there were no significant correlations either between the SUVmax, SUVmean, SUVpeak and the ADCmean (P=0.992, P=0.843 and P=0.894, respectively). The results of this study indicate that the glycolytic rate as measured by FDG-PET and changes in water compartmentalization and water diffusion as measured by the ADC are independent biological phenomena in newly diagnosed DLBCL. Further studies are warranted to assess the complementary roles of these different imaging biomarkers in the evaluation and follow-up of DLBCL. PMID:24795837

  1. Diffusion weighted MRI by spatiotemporal encoding: Analytical description and in vivo validations

    Science.gov (United States)

    Solomon, Eddy; Shemesh, Noam; Frydman, Lucio

    2013-07-01

    Diffusion-weighted (DW) MRI is a powerful modality for studying microstructure in normal and pathological tissues. The accuracy derived from DW MRI depends on the acquisition of quality images, and on a precise assessment of the b-values involved. Conventional DW MRI tends to be of limited use in regions suffering from large magnetic field or chemical shift heterogeneities, which severely distort the MR images. In this study we propose novel sequences based on SPatio-temporal ENcoding (SPEN), which overcome such shortcomings owing to SPEN's inherent robustness to offsets. SPEN, however, relies on the simultaneous application of gradients and radiofrequency-swept pulses, which may impart different diffusion weightings along the spatial axes. These will be further complicated in DW measurements by the diffusion-sensitizing gradients, and will in general lead to complex, spatially-dependent b-values. This study presents a formalism for analyzing these diffusion-weighted SPEN (dSPEN) data, which takes into account the concomitant effects of adiabatic pulses, of the imaging as well as diffusion gradients, and of the cross-terms between them. These analytical b-values derivations are subject to experimental validations in phantom systems and ex vivo spinal cords. Excellent agreement is found between the theoretical predictions and these dSPEN experiments. The ensuing methodology is then demonstrated by in vivo mapping of diffusion in human breast - organs where conventional k-space DW acquisition methods are challenged by both field and chemical shift heterogeneities. These studies demonstrate the increased robustness of dSPEN vis-à-vis comparable DW echo planar imaging, and demonstrate the value of this new methodology for medium- or high-field diffusion measurements in heterogeneous systems.

  2. Short-term evolution of spinal cord damage in multiple sclerosis: a diffusion tensor MRI study

    Energy Technology Data Exchange (ETDEWEB)

    Theaudin, M.; Denier, C.; Adams, D. [AP-HP, CHU Bicetre, Service de Neurologie Adultes, Le Kremlin-Bicetre (France); INSERM, UMR788, Faculte de Medecine Paris Sud, Le Kremlin-Bicetre (France); Saliou, G. [AP-HP, CHU Bicetre, Service de Neuroradiologie, Le Kremlin-Bicetre (France); Ducot, B. [INSERM, U1018, CESP Centre for Research in Epidemiology and Population Health, Faculte de Medecine Paris Sud, Le Kremlin-Bicetre (France); Deiva, K. [Service de Neuropediatrie, Le Kremlin-Bicetre (France); Ducreux, D. [INSERM, UMR788, Faculte de Medecine Paris Sud, Le Kremlin-Bicetre (France); AP-HP, CHU Bicetre, Service de Neuroradiologie, Le Kremlin-Bicetre (France)

    2012-10-15

    The potential of diffusion tensor imaging (DTI) to detect spinal cord abnormalities in patients with multiple sclerosis has already been demonstrated. The objective of this study was to apply DTI techniques to multiple sclerosis patients with a recently diagnosed spinal cord lesion, in order to demonstrate a correlation between variations of DTI parameters and clinical outcome, and to try to identify DTI parameters predictive of outcome. A prospective single-centre study of patients with spinal cord relapse treated by intravenous steroid therapy was made. Patients were assessed clinically and by conventional MRI with DTI sequences at baseline and at 3 months. Sixteen patients were recruited. At 3 months, 12 patients were clinically improved. All but one patient had lower fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values than normal subjects in either inflammatory lesions or normal-appearing spinal cord. Patients who improved at 3 months presented a significant reduction in the radial diffusivity (p = 0.05) in lesions during the follow-up period. They also had a significant reduction in the mean ADC (p = 0.002), axial diffusivity (p = 0.02), radial diffusivity (p = 0.02) and a significant increase in FA values (p = 0.02) in normal-appearing spinal cord. Patients in whom the American Spinal Injury Association sensory score improved at 3 months showed a significantly higher FA (p = 0.009) and lower radial diffusivity (p = 0.04) in inflammatory lesion at baseline compared to patients with no improvement. DTI MRI detects more extensive abnormalities than conventional T2 MRI. A less marked decrease in FA value and more marked decreased in radial diffusivity inside the inflammatory lesion were associated with better outcome. (orig.)

  3. Short-term evolution of spinal cord damage in multiple sclerosis: a diffusion tensor MRI study

    International Nuclear Information System (INIS)

    Theaudin, M.; Denier, C.; Adams, D.; Saliou, G.; Ducot, B.; Deiva, K.; Ducreux, D.

    2012-01-01

    The potential of diffusion tensor imaging (DTI) to detect spinal cord abnormalities in patients with multiple sclerosis has already been demonstrated. The objective of this study was to apply DTI techniques to multiple sclerosis patients with a recently diagnosed spinal cord lesion, in order to demonstrate a correlation between variations of DTI parameters and clinical outcome, and to try to identify DTI parameters predictive of outcome. A prospective single-centre study of patients with spinal cord relapse treated by intravenous steroid therapy was made. Patients were assessed clinically and by conventional MRI with DTI sequences at baseline and at 3 months. Sixteen patients were recruited. At 3 months, 12 patients were clinically improved. All but one patient had lower fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values than normal subjects in either inflammatory lesions or normal-appearing spinal cord. Patients who improved at 3 months presented a significant reduction in the radial diffusivity (p = 0.05) in lesions during the follow-up period. They also had a significant reduction in the mean ADC (p = 0.002), axial diffusivity (p = 0.02), radial diffusivity (p = 0.02) and a significant increase in FA values (p = 0.02) in normal-appearing spinal cord. Patients in whom the American Spinal Injury Association sensory score improved at 3 months showed a significantly higher FA (p = 0.009) and lower radial diffusivity (p = 0.04) in inflammatory lesion at baseline compared to patients with no improvement. DTI MRI detects more extensive abnormalities than conventional T2 MRI. A less marked decrease in FA value and more marked decreased in radial diffusivity inside the inflammatory lesion were associated with better outcome. (orig.)

  4. Elements of random walk and diffusion processes

    CERN Document Server

    Ibe, Oliver C

    2013-01-01

    Presents an important and unique introduction to random walk theory Random walk is a stochastic process that has proven to be a useful model in understanding discrete-state discrete-time processes across a wide spectrum of scientific disciplines. Elements of Random Walk and Diffusion Processes provides an interdisciplinary approach by including numerous practical examples and exercises with real-world applications in operations research, economics, engineering, and physics. Featuring an introduction to powerful and general techniques that are used in the application of physical and dynamic

  5. Study on diffusion anisotropy of cerebral ischemia using diffusion weighted echo-planar MRI

    International Nuclear Information System (INIS)

    Kajima, Toshio

    1997-01-01

    Focal cerebral ischemia was produced by occlusion of the intracranial main cerebral artery with a silicone cylinder in Wistar rats. Diffusion-weighted echo-planar images (DW-EPls) using the motion-probing gradient (MPG) method were acquired at 1-3 hours and 24-48 hours after occlusion. Apparent diffusion coefficients (ADCs) were calculated from these images in ischemic lesions and in normal unoccluded regions. Results were as follows. Ischemic lesions could be detected on the DW-EPIs at 1 hour after occlusion. The ADC of water in the brain tissue was smaller than that of free water as a result of restricted diffusion. Anisotropic diffusion that probably can be attributed to the myelin sheath was observed in the normal white matter. In the ischemic lesions, the ADC decreased rapidly within 1-3 hours after occlusion and then decreased gradually after 24-48 hours. In the ischemic white matter, diffusion anisotropy disappeared at 24-48 hours after occlusion. Diffusion-weighted imaging may have applications in the examination of pathophysiological mechanisms in cerebral ischemia by means of evaluation of ADC and diffusion anisotropy. (author)

  6. Characterization of short white matter fiber bundles in the central area from diffusion tensor MRI

    International Nuclear Information System (INIS)

    Magro, Elsa; Moreau, Tristan; Gibaud, Bernard; Seizeur, Romuald; Morandi, Xavier

    2012-01-01

    Diffusion tensor imaging and tractography allow studying white matter fiber bundles in the human brain in vivo. Electrophysiological studies and postmortem dissections permit improving our knowledge about the short association fibers connecting the pre- and postcentral gyri. The aim of this study was first to extract and analyze the features of these short fiber bundles and secondly to analyze their asymmetry according to the subjects' handedness. Ten right-handed and ten left-handed healthy subjects were included. White matter fiber bundles were extracted using a streamline tractography approach, with two seed regions of interest (ROI) taken from a parcellation of the pre- and postcentral gyri. This parcellation was achieved using T1 magnetic resonance images (MRI) and semi-automatically generated three ROIs within each gyrus. MRI tracks were reconstructed between all pairs of ROIs connecting the adjacent pre- and postcentral gyri. A quantitative analysis was performed on the number of tracks connecting each ROI pair. A statistical analysis studied the repartition of these MRI tracks in the right and left hemispheres and as a function of the subjects' handedness. The quantitative analysis showed an increased density of MRI tracks in the middle part of the central area in each hemisphere of the 20 subjects. The statistical analysis showed significantly more MRI tracks for the left hemisphere, when we consider the whole population, and this difference was presumably driven by the left-handers. These results raise questions about the functional role of these MRI tracks and their relation with laterality. (orig.)

  7. Diffusion Processes Satisfying a Conservation Law Constraint

    Directory of Open Access Journals (Sweden)

    J. Bakosi

    2014-01-01

    Full Text Available We investigate coupled stochastic differential equations governing N nonnegative continuous random variables that satisfy a conservation principle. In various fields a conservation law requires a set of fluctuating variables to be nonnegative and (if appropriately normalized sum to one. As a result, any stochastic differential equation model to be realizable must not produce events outside of the allowed sample space. We develop a set of constraints on the drift and diffusion terms of such stochastic models to ensure that both the nonnegativity and the unit-sum conservation law constraints are satisfied as the variables evolve in time. We investigate the consequences of the developed constraints on the Fokker-Planck equation, the associated system of stochastic differential equations, and the evolution equations of the first four moments of the probability density function. We show that random variables, satisfying a conservation law constraint, represented by stochastic diffusion processes, must have diffusion terms that are coupled and nonlinear. The set of constraints developed enables the development of statistical representations of fluctuating variables satisfying a conservation law. We exemplify the results with the bivariate beta process and the multivariate Wright-Fisher, Dirichlet, and Lochner’s generalized Dirichlet processes.

  8. Diffusion-Weighted MRI for the Assessment of Liver Fibrosis: Principles and Applications

    Directory of Open Access Journals (Sweden)

    Stefano Palmucci

    2015-01-01

    Full Text Available The importance of an early identification of hepatic fibrosis has been emphasized, in order to start therapy and obtain fibrosis regression. Biopsy is the gold-standard method for the assessment of liver fibrosis in chronic liver diseases, but it is limited by complications, interobserver variability, and sampling errors. Several noninvasive methods have been recently introduced into clinical routine, in order to detect liver fibrosis early. One of the most diffuse approaches is represented by diffusion-weighted liver MRI. In this review, the main technical principles are briefly reported in order to explain the rationale for clinical applications. In addition, roles of apparent diffusion coefficient, intravoxel incoherent motion, and relative apparent diffusion coefficient are also reported, showing their advantages and limits.

  9. Enhancing Diffusion MRI Measures By Integrating Grey and White Matter Morphometry With Hyperbolic Wasserstein Distance

    Science.gov (United States)

    Zhang, Wen; Shi, Jie; Yu, Jun; Zhan, Liang; Thompson, Paul M.; Wang, Yalin

    2017-01-01

    In order to improve the preclinical diagnose of Alzheimer's disease (AD), there is a great deal of interest in analyzing the AD related brain structural changes with magnetic resonance image (MRI) analyses. As the major features, variation of the structural connectivity and the cortical surface morphometry provide different views of structural changes to determine whether AD is present on presymptomatic patients. However, the large scale tensor-valued information and relatively low imaging resolution in diffusion MRI (dMRI) have created huge challenges for analysis. In this paper, we propose a novel framework that improves dMRI analysis power by fusing cortical surface morphometry features from structural MRI (sMRI). We first compute the hyperbolic harmonic maps between cortical surfaces with the landmark constraints thus to precisely evaluate surface tensor-based morphometry. Meanwhile, the graph-based analysis of structural connectivity derived from dMRI is conducted. Next, we fuse these two features via the optimal mass transportation (OMT) and eventually the Wasserstein distance (WD) based single image index is computed as a potential clinical multimodality imaging score. We apply our framework to brain images of 20 AD patients and 20 matched healthy controls, randomly chosen from the Alzheimer's Disease Neuroimaging Initiative (AD-NI2) dataset. Our preliminary experimental results of group classification outperformed those of some other single dMRI-based features, such as regional hippocampal volume, mean scores of fractional anisotropy (FA) and mean axial (MD). The novel image fusion pipeline and simple imaging score of structural changes may benefit the preclinical AD and AD prevention research. PMID:28936280

  10. Diffusion-weighted MRI for uveal melanoma liver metastasis detection

    Energy Technology Data Exchange (ETDEWEB)

    Wagner, Mathilde; Petras, Slavomir; Servois, Vincent [Institut Curie, Department of Radiology and Nuclear Medicine, Paris (France); Mariani, Pascale; Cassoux, Nathalie [Institut Curie, Department of Surgery, Paris (France); Bidard, Francois Clement; Rodrigues, Manuel Jorge; Piperno-Neumann, Sophie [Institut Curie, Department of Medical Oncology, Paris (France); Farkhondeh, Fereshteh [Institut Curie, Department of Pathology, Paris (France)

    2015-08-15

    We aimed to assess the sensitivity of diffusion-weighted (DW) magnetic resonance (MR) imaging for the detection of pathologically confirmed uveal melanoma liver metastases (UMLM). Twenty patients who underwent complete surgical resection of their UMLM (N = 83) were included. Pre-surgery liver MR imaging included T2-weighted, T1-weighted, DW and dynamic-gadolinium-enhanced MR sequences. Two radiologists independently reviewed three sets of images (DW / morphologic-dynamic / combined) for each patient using intraoperative and pathological findings as a standard of reference. The sensitivities of the morphologic-dynamic and DW images for UMLM detection were 63 % and 59 %, respectively, for reader 1 (R1) and 64 % and 53 %, for reader 2 (R2). Sensitivity of the combined set was higher than sensitivity in the two other sets (R1:69 %, R2:67 %), but was only significantly different than the sensitivity of the DW images (McNemar test). For the three sets and the two readers, the sensitivity for UMLM smaller than 5 mm (37-46 %) was significantly lower than that for UMLM larger than 5 mm (67-90 %). The sensitivity for UMLM located in the subcapsular area (41-54 %) was significantly lower than that for intraparenchymal UMLM (68-86 %) (Chi-square test). Our study shows that the addition of DW imaging to morphologic-dynamic images does not significantly increase MR sensitivities for UMLM detection. (orig.)

  11. Conditional Granger Causality of Diffusion Processes

    Czech Academy of Sciences Publication Activity Database

    Wahl, B.; Feudel, U.; Hlinka, Jaroslav; Wächter, M.; Peinke, J.; Freund, J.A.

    2017-01-01

    Roč. 90, č. 10 (2017), č. článku 197. ISSN 1434-6028 R&D Projects: GA ČR GA13-23940S; GA MZd(CZ) NV15-29835A Institutional support: RVO:67985807 Keywords : Granger causality * stochastic process * diffusion process * nonlinear dynamical systems Subject RIV: BB - Applied Statistics, Operational Research OBOR OECD: Computer sciences, information science, bioinformathics (hardware development to be 2.2, social aspect to be 5.8) Impact factor: 1.461, year: 2016

  12. Surface-Based fMRI-Driven Diffusion Tractography in the Presence of Significant Brain Pathology: A Study Linking Structure and Function in Cerebral Palsy

    Science.gov (United States)

    Cunnington, Ross; Boyd, Roslyn N.; Rose, Stephen E.

    2016-01-01

    Diffusion MRI (dMRI) tractography analyses are difficult to perform in the presence of brain pathology. Automated methods that rely on cortical parcellation for structural connectivity studies often fail, while manually defining regions is extremely time consuming and can introduce human error. Both methods also make assumptions about structure-function relationships that may not hold after cortical reorganisation. Seeding tractography with functional-MRI (fMRI) activation is an emerging method that reduces these confounds, but inherent smoothing of fMRI signal may result in the inclusion of irrelevant pathways. This paper describes a novel fMRI-seeded dMRI-analysis pipeline based on surface-meshes that reduces these issues and utilises machine-learning to generate task specific white matter pathways, minimising the requirement for manually-drawn ROIs. We directly compared this new strategy to a standard voxelwise fMRI-dMRI approach, by investigating correlations between clinical scores and dMRI metrics of thalamocortical and corticomotor tracts in 31 children with unilateral cerebral palsy. The surface-based approach successfully processed more participants (87%) than the voxel-based approach (65%), and provided significantly more-coherent tractography. Significant correlations between dMRI metrics and five clinical scores of function were found for the more superior regions of these tracts. These significant correlations were stronger and more frequently found with the surface-based method (15/20 investigated were significant; R2 = 0.43–0.73) than the voxelwise analysis (2 sig. correlations; 0.38 & 0.49). More restricted fMRI signal, better-constrained tractography, and the novel track-classification method all appeared to contribute toward these differences. PMID:27487011

  13. Detection of electroporation-induced membrane permeabilization states in the brain using diffusion-weighted MRI

    DEFF Research Database (Denmark)

    Mahmood, Faisal; Hansen, Rasmus H; Agerholm-Larsen, Birgit

    2015-01-01

    BACKGROUND: Tissue permeabilization by electroporation (EP) is a promising technique to treat certain cancers. Non-invasive methods for verification of induced permeabilization are important, especially in deep-seated cancers. In this study we evaluated diffusion-weighted magnetic resonance imaging...... (NP), transient membrane permeabilization (TMP), and permanent membrane permeabilization (PMP), respectively. DW-MRI was acquired 5 minutes, 2 hours, 24 hours and 48 hours after EP. Histology was performed for validation of the permeabilization states. Tissue content of water, Na+, K+, Ca2...... minutes after EP, compared to NP. Kurtosis was also significantly higher at 24 hours (pstates, supporting the DW-MRI findings. We conclude that DW-MRI is capable of detecting EP...

  14. Changes on diffusion-weighted MRI with focal motor status epilepticus: case report

    International Nuclear Information System (INIS)

    Loevblad, K.O.; Senn, P.; Zutter, D.; Bassetti, C.; Donati, F.; Loevblad, K.O.; Zeller, O.; Schroth, G.

    2003-01-01

    Transient imaging abnormalities, including changes on diffusion-weighted imaging (DWI), may be seen in focal status epilepticus. The changes on DWI provide an insight into the pathophysiology. We report a 53-year-old man with focal motor status epilepticus involving the left hand, arm and face with focal slowing on EEG. The apparent diffusion coefficients (ADC) were higher in the affected hemisphere than on the other side. At 10 days and 6 weeks after the end of the seizures, we saw normal ADCs and atrophy of the affected hemisphere. We conclude that the MRI findings indicate both cytotoxic and vasogenic oedema during seizure activity and subsequent loss of brain parenchyma. (orig.)

  15. Changes on diffusion-weighted MRI with focal motor status epilepticus: case report

    Energy Technology Data Exchange (ETDEWEB)

    Loevblad, K O [Neuroradiology, Radiodiagnostic, Hopital Cantonal de Geneve HUG, Geneve (Switzerland); Senn, P; Zutter, D; Bassetti, C; Donati, F [Dept. of Neurology, Inselspital, Univ. Hospital, Berne (Switzerland); Loevblad, K O; Zeller, O; Schroth, G [Div. of Neuroradiology, Inselspital, Univ. Hospital, Berne (Switzerland)

    2003-04-01

    Transient imaging abnormalities, including changes on diffusion-weighted imaging (DWI), may be seen in focal status epilepticus. The changes on DWI provide an insight into the pathophysiology. We report a 53-year-old man with focal motor status epilepticus involving the left hand, arm and face with focal slowing on EEG. The apparent diffusion coefficients (ADC) were higher in the affected hemisphere than on the other side. At 10 days and 6 weeks after the end of the seizures, we saw normal ADCs and atrophy of the affected hemisphere. We conclude that the MRI findings indicate both cytotoxic and vasogenic oedema during seizure activity and subsequent loss of brain parenchyma. (orig.)

  16. Diffusion-weighted MRI and quantitative biophysical modeling of hippocampal neurite loss in chronic stress.

    Directory of Open Access Journals (Sweden)

    Peter Vestergaard-Poulsen

    Full Text Available Chronic stress has detrimental effects on physiology, learning and memory and is involved in the development of anxiety and depressive disorders. Besides changes in synaptic formation and neurogenesis, chronic stress also induces dendritic remodeling in the hippocampus, amygdala and the prefrontal cortex. Investigations of dendritic remodeling during development and treatment of stress are currently limited by the invasive nature of histological and stereological methods. Here we show that high field diffusion-weighted MRI combined with quantitative biophysical modeling of the hippocampal dendritic loss in 21 day restraint stressed rats highly correlates with former histological findings. Our study strongly indicates that diffusion-weighted MRI is sensitive to regional dendritic loss and thus a promising candidate for non-invasive studies of dendritic plasticity in chronic stress and stress-related disorders.

  17. High-fidelity meshes from tissue samples for diffusion MRI simulations.

    Science.gov (United States)

    Panagiotaki, Eleftheria; Hall, Matt G; Zhang, Hui; Siow, Bernard; Lythgoe, Mark F; Alexander, Daniel C

    2010-01-01

    This paper presents a method for constructing detailed geometric models of tissue microstructure for synthesizing realistic diffusion MRI data. We construct three-dimensional mesh models from confocal microscopy image stacks using the marching cubes algorithm. Random-walk simulations within the resulting meshes provide synthetic diffusion MRI measurements. Experiments optimise simulation parameters and complexity of the meshes to achieve accuracy and reproducibility while minimizing computation time. Finally we assess the quality of the synthesized data from the mesh models by comparison with scanner data as well as synthetic data from simple geometric models and simplified meshes that vary only in two dimensions. The results support the extra complexity of the three-dimensional mesh compared to simpler models although sensitivity to the mesh resolution is quite robust.

  18. Dynamics of the connectome in Huntington's disease: A longitudinal diffusion MRI study

    OpenAIRE

    Odish, Omar F.F.; Caeyenberghs, Karen; Hosseini, Hadi; van den Bogaard, Simon J.A.; Roos, Raymund A.C.; Leemans, Alexander

    2015-01-01

    Abstract Objectives To longitudinally investigate the connectome in different stages of Huntington's disease (HD) by applying graph theoretical analysis to diffusion MRI data. Experimental design We constructed weighted structural networks and calculated their topological properties. Twenty-two premanifest (preHD), 10 early manifest HD and 24 healthy controls completed baseline and 2 year follow-up scans. We stratified the preHD group based on their predicted years to disease onset into a far...

  19. Diffusion MRI and the Detection of Alterations Following Traumatic Brain Injury

    Science.gov (United States)

    2017-06-13

    vascular injury, disruption of water home- ostasis), changes in tissue composition (e.g., increased or decreased cellu- larity), and alterations in...related alterations Tissue environment Expected diffusion changes Major citations dMRI evidence Neurons cell loss necrosis and apoptosis atrophy...structure and signaling, vascular coupling, and waste removal, among others. Astrocytes are at least as numerous as neurons in the brain (Herculano-Houzel

  20. The contribution of MRI to the diagnosis of diffuse meningeal lesions

    International Nuclear Information System (INIS)

    Kreuzberg, B.; Kastner, J.; Ferda, J.

    2004-01-01

    We analysed MRI findings in patients in whom a diffuse abnormality of the meninges was revealed by MRI. We looked at T1 and T2-weighted spin-echo or fast spin-echo images and contrast-enhanced T1-weighted images. There were 15 patients with abnormalities on MRI, clinically suspected in ten. Four had meningoencephalitis, one meningeal and subcortical sarcoidosis nodules, four meningeal malignancies - one disseminated oligodendroglioma, one with meningeal infiltration around an adenocarcinoma, three meningeal infiltration by a haematological malignancy, and one a chronic subdural haematoma without a history of injury. We excluded patients with primary meningeal tumours and typical injury-related meningeal bleeding. The relatively small number of patients is due to both the infrequency of diffuse meningeal disease and to the low frequency of suspected meningeal pathology as an indication for MRI. The latter's diagnostic contribution is greatest in infectious disease and neoplastic infiltration, and less obvious in haematological malignancies. Contrast-enhanced T1-weighted images are most useful. (orig.)

  1. Evaluation of malignant and benign renal lesions using diffusion-weighted MRI with multiple b values

    International Nuclear Information System (INIS)

    Erbay, Gurcan; Koc, Zafer; Karadeli, Elif; Kuzgunbay, Baris; Goren, M. Resit; Bal, Nebil

    2012-01-01

    Background: Limited data are available regarding the use of diffusion-weighted (DW) magnetic resonance imaging (MRI) with multiple b values for characterization of renal lesions. Purpose: To demonstrate and compare the diagnostic performance of DW-MRI with multiple b values for renal lesion characterization. Material and Methods: Sixty-three lesions (36 malignant, 27 benign) in 60 consecutive patients (48 men, 12 women; age 60 ± 12.5 years) with solid/cystic renal lesion diagnosed after MRI were included prospectively. Single-shot echo-planar DW abdominal MRI (1.5T) was obtained using seven b values with eight apparent diffusion coefficient (ADC) maps. Contrast-to-noise ratios (CNRs), signal intensities, lesion ADCs, and lesion/normal parenchyma ADC ratios were analyzed. Receiver-operating characteristic analysis was performed. Results: The mean signal intensities of malignant lesions (at b0, 50, and 200 s/mm 2 ) were significantly lower than those of benign lesions (P 2 . ADC with all b values could better distinguish between benign and malignant lesions. A 1.35 x 10 -3 mm 2 /s threshold ADC value permitted this distinction with 85.2% sensitivity and 65.6% specificity. The lesion/normal parenchyma ADC ratio was more effective than the lesion ADC. Conclusion: In addition to the ADC value, the signal intensity curve on DW images using multiple b values could be helpful for differentiation of malignant and benign renal lesions

  2. Diffusion MRI: A New Strategy for Assessment of Cancer Therapeutic Efficacy

    Directory of Open Access Journals (Sweden)

    Thomas L. Chenevert

    2002-10-01

    Full Text Available The use of anatomical imaging in clinical oncology practice traditionally relies on comparison of patient scans acquired before and following completion of therapeutic intervention. Therapeutic success is typically determined from inspection of gross anatomical images to assess changes in tumor size. Imaging could provide significant additional insight into therapeutic impact if a specific parameter or combination of parameters could be identified which reflect tissue changes at the cellular or physiologic level. This would provide an early indicator of treatment response/outcome in an individual patient before completion of therapy. Moreover, response of a tumor to therapeutic intervention may be heterogeneous. The use of imaging could assist in delineating therapeutic-induced spatial heterogeneity within a tumor mass by providing information related to specific regions that are resistant or responsive to treatment. Largely untapped potential resides in exploratory methods such as diffusion MRI, which is a non-volumetric intravoxel measure of tumor response based upon water molecular mobility. Alterations in water mobility reflect changes in tissue structure at the cellular level. While the clinical utility of diffusion MRI for oncologic practice is still under active investigation, this overview on the use of diffusion MRI for the evaluation of brain tumors will serve to introduce how this approach may be applied in the future for the management of patients with solid tumors.

  3. Diffuse periventricular leukomalacia in preterm children: assessment of grey matter changes by MRI

    International Nuclear Information System (INIS)

    Tzarouchi, L.C.; Xydis, V.; Zikou, A.K.; Papastefanaki, M.; Argyropoulou, Maria I.; Drougia, A.; Andronikou, S.; Astrakas, L.G.

    2011-01-01

    Preterm children may have cognitive deficits and behavioural disorders suggestive of grey matter (GM) injury. The prevalence is higher in preterm children with diffuse periventricular leukomalacia (dPVL). Evaluate changes in the volume of 116 GM areas in preterm children with dPVL. Eleven preterm children with dPVL, gestational age 32.8 ± 2.6 weeks, examined at corrected age 22.0 ± 18.2 months and 33 matched preterm controls with normal brain MRI were studied. Volumes of 116 individual GM areas, and white matter/cerebrospinal fluid (WM/CSF) ratio were calculated on T1-weighted high-resolution images after segmentation. Relative to controls, children with dPVL had decreased GM volume of the hippocampus, amygdala, and frontal lobes and temporal middle gyrus (P < 0.05); increased GM volume of the putamen, thalamus, globus pallidum, superior temporal gyrus and of the parietal and occipital lobes (P < 0.05) and lower WM volume/higher CSF volume (P < 0.05). WM/CSF ratios also differed (P < 0.05). Preterm children with dPVL have increased regional GM volume in some areas probably related with a process of brain plasticity-regeneration and reduced GM volume in areas associated with cognition and memory. (orig.)

  4. Diffuse periventricular leukomalacia in preterm children: assessment of grey matter changes by MRI

    Energy Technology Data Exchange (ETDEWEB)

    Tzarouchi, L.C.; Xydis, V.; Zikou, A.K.; Papastefanaki, M.; Argyropoulou, Maria I. [University of Ioannina, Department of Radiology, Medical School, Ioannina (Greece); Drougia, A.; Andronikou, S. [University of Ioannina, Neonatal Intensive Care Unit, Child Health Department, Medical School, Ioannina (Greece); Astrakas, L.G. [University of Ioannina, Department of Medical Physics, Medical School, Ioannina (Greece)

    2011-12-15

    Preterm children may have cognitive deficits and behavioural disorders suggestive of grey matter (GM) injury. The prevalence is higher in preterm children with diffuse periventricular leukomalacia (dPVL). Evaluate changes in the volume of 116 GM areas in preterm children with dPVL. Eleven preterm children with dPVL, gestational age 32.8 {+-} 2.6 weeks, examined at corrected age 22.0 {+-} 18.2 months and 33 matched preterm controls with normal brain MRI were studied. Volumes of 116 individual GM areas, and white matter/cerebrospinal fluid (WM/CSF) ratio were calculated on T1-weighted high-resolution images after segmentation. Relative to controls, children with dPVL had decreased GM volume of the hippocampus, amygdala, and frontal lobes and temporal middle gyrus (P < 0.05); increased GM volume of the putamen, thalamus, globus pallidum, superior temporal gyrus and of the parietal and occipital lobes (P < 0.05) and lower WM volume/higher CSF volume (P < 0.05). WM/CSF ratios also differed (P < 0.05). Preterm children with dPVL have increased regional GM volume in some areas probably related with a process of brain plasticity-regeneration and reduced GM volume in areas associated with cognition and memory. (orig.)

  5. Complex diffusion process for noise reduction

    DEFF Research Database (Denmark)

    Nadernejad, Ehsan; Barari, A.

    2014-01-01

    equations (PDEs) in image restoration and de-noising prompted many researchers to search for an improvement in the technique. In this paper, a new method is presented for signal de-noising, based on PDEs and Schrodinger equations, named as complex diffusion process (CDP). This method assumes that variations...... for signal de-noising. To evaluate the performance of the proposed method, a number of experiments have been performed using Sinusoid, multi-component and FM signals cluttered with noise. The results indicate that the proposed method outperforms the approaches for signal de-noising known in prior art....

  6. Evaluation of conventional, dynamic contrast enhanced and diffusion weighted MRI for quantitative Crohn's disease assessment with histopathology of surgical specimens

    NARCIS (Netherlands)

    Tielbeek, Jeroen A. W.; Ziech, Manon L. W.; Li, Zhang; Lavini, Cristina; Bipat, Shandra; Bemelman, Willem A.; Roelofs, Joris J. T. H.; Ponsioen, Cyriel Y.; Vos, Frans M.; Stoker, Jaap

    2014-01-01

    To prospectively compare conventional MRI sequences, dynamic contrast enhanced (DCE) MRI and diffusion weighted imaging (DWI) with histopathology of surgical specimens in Crohn's disease. 3-T MR enterography was performed in consecutive Crohn's disease patients scheduled for surgery within 4 weeks.

  7. Assessment of the link between quantitative biexponential diffusion-weighted imaging and contrast-enhanced MRI in the liver

    NARCIS (Netherlands)

    Dijkstra, Hildebrand; Oudkerk, Matthijs; Kappert, Peter; Sijens, Paul E.

    Purpose: To investigate if intravoxel incoherent motion (IVIM) modeled diffusion-weighted imaging (DWI) can be linked to contrast-enhanced (CE-)MRI in liver parenchyma and liver lesions. Methods: Twenty-five patients underwent IVIM-DWI followed by multiphase CE-MRI using Gd-EOB-DTPA (n = 20) or

  8. Parametric statistical inference for discretely observed diffusion processes

    DEFF Research Database (Denmark)

    Pedersen, Asger Roer

    Part 1: Theoretical results Part 2: Statistical applications of Gaussian diffusion processes in freshwater ecology......Part 1: Theoretical results Part 2: Statistical applications of Gaussian diffusion processes in freshwater ecology...

  9. Diffusion-weighted MRI for detecting prostate tumour in men at increased genetic risk

    International Nuclear Information System (INIS)

    Souza, Nandita M. de; Morgan, Veronica A.; Bancroft, Elizabeth; Sohaib, S. Aslam; Giles, Sharon L.; Kote-Jarai, Zsofia; Castro, Elena; Hazell, Steven; Jafar, Maysam; Eeles, Rosalind

    2014-01-01

    •Endorectal T2W + DW-MRI is potentially useful for prostate cancer screening.•MRI is specific for detecting prostate cancer in men with increased genetic risk.•Detection of prostate cancer in men at genetically low risk with MRI is limited. Endorectal T2W + DW-MRI is potentially useful for prostate cancer screening. MRI is specific for detecting prostate cancer in men with increased genetic risk. Detection of prostate cancer in men at genetically low risk with MRI is limited. Diffusion-weighted (DW)-MRI is invaluable in detecting prostate cancer. We determined its sensitivity and specificity and established interobserver agreement for detecting tumour in men with a family history of prostate cancer stratified by genetic risk. 51 men with a family history of prostate cancer underwent T2-W + DW-endorectal MRI at 3.0 T. Presence of tumour was noted at right and left apex, mid and basal prostate sextants by 2 independent observers, 1 experienced and the other inexperienced in endorectal MRI. Sensitivity and specificity against a 10-core sampling technique (lateral and medial cores at each level considered together) in men with >2× population risk based on 71 SNP analysis versus those with lower genetic risk scores was established. Interobserver agreement was determined at a subject level. Biopsies indicated cancer in 28 sextants in 13/51 men; 32 of 51 men had twice the population risk (>0.25) based on 71 SNP profiling. Sensitivity/specificity per-subject for patients was 90.0%/86.4% (high-risk) vs. 66.7%/100% (low-risk, observer 1) and 60.0%/86.3% (high-risk) vs. 33.3%/93.8% (low-risk, observer 2) with moderate overall inter-observer agreement (kappa = 0.42). Regional sensitivities/specificities for high-risk vs. low-risk for observer 1 apex 72.2%/100% [33.3%/100%], mid 100%/93.1% [100%/97.3%], base 16.7%/98.3% [0%/100%] and for observer 2 apex 36.4%/98.1% [0%/100%], mid 28.6%/96.5% [100%/100%], base 20%/100% [0%/97.3%] were poorer as they failed to detect

  10. Improving the realism of white matter numerical phantoms: a step towards a better understanding of the influence of structural disorders in diffusion MRI

    Science.gov (United States)

    Ginsburger, Kévin; Poupon, Fabrice; Beaujoin, Justine; Estournet, Delphine; Matuschke, Felix; Mangin, Jean-François; Axer, Markus; Poupon, Cyril

    2018-02-01

    White matter is composed of irregularly packed axons leading to a structural disorder in the extra-axonal space. Diffusion MRI experiments using oscillating gradient spin echo sequences have shown that the diffusivity transverse to axons in this extra-axonal space is dependent on the frequency of the employed sequence. In this study, we observe the same frequency-dependence using 3D simulations of the diffusion process in disordered media. We design a novel white matter numerical phantom generation algorithm which constructs biomimicking geometric configurations with few design parameters, and enables to control the level of disorder of the generated phantoms. The influence of various geometrical parameters present in white matter, such as global angular dispersion, tortuosity, presence of Ranvier nodes, beading, on the extra-cellular perpendicular diffusivity frequency dependence was investigated by simulating the diffusion process in numerical phantoms of increasing complexity and fitting the resulting simulated diffusion MR signal attenuation with an adequate analytical model designed for trapezoidal OGSE sequences. This work suggests that angular dispersion and especially beading have non-negligible effects on this extracellular diffusion metrics that may be measured using standard OGSE DW-MRI clinical protocols.

  11. Repeated diffusion MRI reveals earliest time point for stratification of radiotherapy response in brain metastases

    DEFF Research Database (Denmark)

    Mahmood, Faisal; Johannesen, Helle H; Geertsen, Poul

    2017-01-01

    An imaging biomarker for early prediction of treatment response potentially provides a non-invasive tool for better prognostics and individualized management of the disease. Radiotherapy (RT) response is generally related to changes in gross tumor volume manifesting months later. In this prospect......An imaging biomarker for early prediction of treatment response potentially provides a non-invasive tool for better prognostics and individualized management of the disease. Radiotherapy (RT) response is generally related to changes in gross tumor volume manifesting months later....... In this prospective study we investigated the apparent diffusion coefficient (ADC), perfusion fraction and pseudo diffusion coefficient derived from diffusion weighted MRI as potential early biomarkers for radiotherapy response of brain metastases. It was a particular aim to assess the optimal time point...

  12. Report of diffusion-weighted MRI in two cases with different cerebral hydatid disease

    Energy Technology Data Exchange (ETDEWEB)

    Kitis, O.; Calli, C.; Yunten, N. [Ege Univ., Izmir (Turkey). Dept. of Radiology

    2004-02-01

    To present MRI findings in two cases of cerebral hydatid disease with an emphasis on diffusion-weighted imaging (DWI) findings of Echinococcus granulosus (EG) versus Echinococcus alveolaris (EA). EG lesions were isointense with cerebrospinal fluid in all sequences including DWI. On DWI, EA lesions remained hypointense on b = 1000 s/mm2 diffusion-weighted images. Apparent diffusion coefficient (ADC) values of EG and EA lesions were completely different from each other, 2.88 {+-} 0.24 x 10{sup -3} s/mm{sup 2} and 1.33 {+-} 0.15 x 10{sup -3} s/mm{sup 2}, respectively. The ADC values could not be used to discriminate from other differential diagnoses.

  13. Report of diffusion-weighted MRI in two cases with different cerebral hydatid disease

    International Nuclear Information System (INIS)

    Kitis, O.; Calli, C.; Yunten, N.

    2004-01-01

    To present MRI findings in two cases of cerebral hydatid disease with an emphasis on diffusion-weighted imaging (DWI) findings of Echinococcus granulosus (EG) versus Echinococcus alveolaris (EA). EG lesions were isointense with cerebrospinal fluid in all sequences including DWI. On DWI, EA lesions remained hypointense on b = 1000 s/mm2 diffusion-weighted images. Apparent diffusion coefficient (ADC) values of EG and EA lesions were completely different from each other, 2.88 ± 0.24 x 10 -3 s/mm 2 and 1.33 ± 0.15 x 10 -3 s/mm 2 , respectively. The ADC values could not be used to discriminate from other differential diagnoses

  14. Assessment of axonal degeneration in Alzheimer's disease with diffusion tensor MRI

    International Nuclear Information System (INIS)

    Stahl, R.; Dietrich, O.; Reiser, M.F.; Schoenberg, S.O.; Teipel, S.; Hampel, H.

    2003-01-01

    Alzheimer disease (AD) causes cortical degeneration with subsequent degenerative changes of the white matter. The aim of this study was to investigate the extent of white matter tissue damage of patients with Alzheimer's disease in comparison with healthy subjects using diffusion tensor MRI (DTI). The value of integrated parallel imaging techniques (iPAT) for reduction of image distortion was assessed. We studied 9 patients with mild AD and 10 age and gender matched healthy controls. DTI brain scans were obtained on a 1.5 tesla system (Siemens Magnetom Sonata) using parallel imaging (iPAT) and an EPI diffusion sequence with TE/TR 71 ms/6000 ms. We used an 8-element head coil and a GRAPPA reconstruction algorithm with an acceleration factor of 2. From the tensor, the mean diffusivity (D), the fractional anisotropy (FA), and the relative anisotropy (RA) of several white matter regions were determined. FA was significantly lower (p [de

  15. Detecting causality in policy diffusion processes

    Science.gov (United States)

    Grabow, Carsten; Macinko, James; Silver, Diana; Porfiri, Maurizio

    2016-08-01

    A universal question in network science entails learning about the topology of interaction from collective dynamics. Here, we address this question by examining diffusion of laws across US states. We propose two complementary techniques to unravel determinants of this diffusion process: information-theoretic union transfer entropy and event synchronization. In order to systematically investigate their performance on law activity data, we establish a new stochastic model to generate synthetic law activity data based on plausible networks of interactions. Through extensive parametric studies, we demonstrate the ability of these methods to reconstruct networks, varying in size, link density, and degree heterogeneity. Our results suggest that union transfer entropy should be preferred for slowly varying processes, which may be associated with policies attending to specific local problems that occur only rarely or with policies facing high levels of opposition. In contrast, event synchronization is effective for faster enactment rates, which may be related to policies involving Federal mandates or incentives. This study puts forward a data-driven toolbox to explain the determinants of legal activity applicable to political science, across dynamical systems, information theory, and complex networks.

  16. The Gini coefficient: a methodological pilot study to assess fetal brain development employing postmortem diffusion MRI

    Energy Technology Data Exchange (ETDEWEB)

    Viehweger, Adrian; Sorge, Ina; Hirsch, Wolfgang [University Hospital Leipzig, Department of Pediatric Radiology, Leipzig (Germany); Riffert, Till; Dhital, Bibek; Knoesche, Thomas R.; Anwander, Alfred [Max Planck Institute for Human Cognitive and Brain Sciences, Leipzig (Germany); Stepan, Holger [University Leipzig, Department of Obstetrics, Leipzig (Germany)

    2014-10-15

    Diffusion-weighted imaging (DWI) is important in the assessment of fetal brain development. However, it is clinically challenging and time-consuming to prepare neuromorphological examinations to assess real brain age and to detect abnormalities. To demonstrate that the Gini coefficient can be a simple, intuitive parameter for modelling fetal brain development. Postmortem fetal specimens(n = 28) were evaluated by diffusion-weighted imaging (DWI) on a 3-T MRI scanner using 60 directions, 0.7-mm isotropic voxels and b-values of 0, 150, 1,600 s/mm{sup 2}. Constrained spherical deconvolution (CSD) was used as the local diffusion model. Fractional anisotropy (FA), apparent diffusion coefficient (ADC) and complexity (CX) maps were generated. CX was defined as a novel diffusion metric. On the basis of those three parameters, the Gini coefficient was calculated. Study of fetal brain development in postmortem specimens was feasible using DWI. The Gini coefficient could be calculated for the combination of the three diffusion parameters. This multidimensional Gini coefficient correlated well with age (Adjusted R{sup 2} = 0.59) between the ages of 17 and 26 gestational weeks. We propose a new method that uses an economics concept, the Gini coefficient, to describe the whole brain with one simple and intuitive measure, which can be used to assess the brain's developmental state. (orig.)

  17. The Gini coefficient: a methodological pilot study to assess fetal brain development employing postmortem diffusion MRI

    International Nuclear Information System (INIS)

    Viehweger, Adrian; Sorge, Ina; Hirsch, Wolfgang; Riffert, Till; Dhital, Bibek; Knoesche, Thomas R.; Anwander, Alfred; Stepan, Holger

    2014-01-01

    Diffusion-weighted imaging (DWI) is important in the assessment of fetal brain development. However, it is clinically challenging and time-consuming to prepare neuromorphological examinations to assess real brain age and to detect abnormalities. To demonstrate that the Gini coefficient can be a simple, intuitive parameter for modelling fetal brain development. Postmortem fetal specimens(n = 28) were evaluated by diffusion-weighted imaging (DWI) on a 3-T MRI scanner using 60 directions, 0.7-mm isotropic voxels and b-values of 0, 150, 1,600 s/mm 2 . Constrained spherical deconvolution (CSD) was used as the local diffusion model. Fractional anisotropy (FA), apparent diffusion coefficient (ADC) and complexity (CX) maps were generated. CX was defined as a novel diffusion metric. On the basis of those three parameters, the Gini coefficient was calculated. Study of fetal brain development in postmortem specimens was feasible using DWI. The Gini coefficient could be calculated for the combination of the three diffusion parameters. This multidimensional Gini coefficient correlated well with age (Adjusted R 2 = 0.59) between the ages of 17 and 26 gestational weeks. We propose a new method that uses an economics concept, the Gini coefficient, to describe the whole brain with one simple and intuitive measure, which can be used to assess the brain's developmental state. (orig.)

  18. Bessel Fourier orientation reconstruction: an analytical EAP reconstruction using multiple shell acquisitions in diffusion MRI.

    Science.gov (United States)

    Hosseinbor, Ameer Pasha; Chung, Moo K; Wu, Yu-Chien; Alexander, Andrew L

    2011-01-01

    The estimation of the ensemble average propagator (EAP) directly from q-space DWI signals is an open problem in diffusion MRI. Diffusion spectrum imaging (DSI) is one common technique to compute the EAP directly from the diffusion signal, but it is burdened by the large sampling required. Recently, several analytical EAP reconstruction schemes for multiple q-shell acquisitions have been proposed. One, in particular, is Diffusion Propagator Imaging (DPI) which is based on the Laplace's equation estimation of diffusion signal for each shell acquisition. Viewed intuitively in terms of the heat equation, the DPI solution is obtained when the heat distribution between temperatuere measurements at each shell is at steady state. We propose a generalized extension of DPI, Bessel Fourier Orientation Reconstruction (BFOR), whose solution is based on heat equation estimation of the diffusion signal for each shell acquisition. That is, the heat distribution between shell measurements is no longer at steady state. In addition to being analytical, the BFOR solution also includes an intrinsic exponential smootheing term. We illustrate the effectiveness of the proposed method by showing results on both synthetic and real MR datasets.

  19. Arcuate fasciculus laterality by diffusion tensor imaging correlates with language laterality by functional MRI in preadolescent children.

    Science.gov (United States)

    Sreedharan, Ruma Madhu; Menon, Amitha C; James, Jija S; Kesavadas, Chandrasekharan; Thomas, Sanjeev V

    2015-03-01

    Language lateralization is unique to humans. Functional MRI (fMRI) and diffusion tensor imaging (DTI) enable the study of language areas and white matter fibers involved in language, respectively. The objective of this study was to correlate arcuate fasciculus (AF) laterality by diffusion tensor imaging with that by fMRI in preadolescent children which has not yet been reported. Ten children between 8 and 12 years were subjected to fMRI and DTI imaging using Siemens 1.5 T MRI. Two language fMRI paradigms--visual verb generation and word pair task--were used. Analysis was done using SPM8 software. In DTI, the fiber volume of the arcuate fasciculus (AFV) and fractional anisotropy (FA) was measured. The fMRI Laterality Index (fMRI-LI) and DTI Laterality Index (DTI-LI) were calculated and their correlation assessed using the Pearson Correlation Index. Of ten children, mean age 10.6 years, eight showed left lateralization while bilateral language lateralization was seen in two. AFV by DTI was more on the left side in seven of the eight children who had left lateralization by fMRI. DTI could not trace the AF in one child. Of the two with bilateral language lateralization on fMRI, one showed larger AFV on the right side while the other did not show any asymmetry. There was a significant correlation (p laterality in children with a high degree of correlation between the two imaging modalities.

  20. MRI shows thickening and altered diffusion in the median and ulnar nerves in multifocal motor neuropathy

    Energy Technology Data Exchange (ETDEWEB)

    Haakma, Wieke [University Medical Center Utrecht, Department of Radiology, Utrecht (Netherlands); Aarhus University, Department of Forensic Medicine and Comparative Medicine Lab, Aarhus (Denmark); Jongbloed, Bas A.; Goedee, H.S.; Berg, Leonard H. van den; Pol, W.L. van der [University Medical Center Utrecht, Brain Centre Rudolf Magnus, Department of Neurology and Neurosurgery, Utrecht (Netherlands); Froeling, Martijn; Bos, Clemens; Hendrikse, Jeroen [University Medical Center Utrecht, Department of Radiology, Utrecht (Netherlands); Leemans, Alexander [University Medical Center Utrecht, Image Sciences Institute, Utrecht (Netherlands)

    2017-05-15

    To study disease mechanisms in multifocal motor neuropathy (MMN) with magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) of the median and ulnar nerves. We enrolled ten MMN patients, ten patients with amyotrophic lateral sclerosis (ALS) and ten healthy controls (HCs). Patients underwent MRI (in a prone position) and nerve conduction studies. DTI and fat-suppressed T2-weighted scans of the forearms were performed on a 3.0T MRI scanner. Fibre tractography of the median and ulnar nerves was performed to extract diffusion parameters: fractional anisotropy (FA), mean (MD), axial (AD) and radial (RD) diffusivity. Cross-sectional areas (CSA) were measured on T2-weighted scans. Forty-five out of 60 arms were included in the analysis. AD was significantly lower in MMN patients (2.20 ± 0.12 x 10{sup -3} mm{sup 2}/s) compared to ALS patients (2.31 ± 0.17 x 10{sup -3} mm{sup 2}/s; p < 0.05) and HCs (2.31± 0.17 x 10{sup -3} mm{sup 2}/s; p < 0.05). Segmental analysis showed significant restriction of AD, RD and MD (p < 0.005) in the proximal third of the nerves. CSA was significantly larger in MMN patients compared to ALS patients and HCs (p < 0.01). Thickening of nerves is compatible with changes in the myelin sheath structure, whereas lowered AD values suggest axonal dysfunction. These findings suggest that myelin and axons are diffusely involved in MMN pathogenesis. (orig.)

  1. Characterization of short white matter fiber bundles in the central area from diffusion tensor MRI

    Energy Technology Data Exchange (ETDEWEB)

    Magro, Elsa [INSERM U 1099/Universite de Rennes 1, Equipe MediCIS, Faculte de Medecine, Rennes Cedex (France); CHU Cavale Blanche, Service de Neurochirurgie, Pole Neurolocomoteur, Brest (France); Moreau, Tristan; Gibaud, Bernard [INSERM U 1099/Universite de Rennes 1, Equipe MediCIS, Faculte de Medecine, Rennes Cedex (France); Seizeur, Romuald [INSERM U 1099/Universite de Rennes 1, Equipe MediCIS, Faculte de Medecine, Rennes Cedex (France); CHU Cavale Blanche, Service de Neurochirurgie, Pole Neurolocomoteur, Brest (France); INSERM UMR 1101 LaTIM, Brest (France); Morandi, Xavier [INSERM U 1099/Universite de Rennes 1, Equipe MediCIS, Faculte de Medecine, Rennes Cedex (France); CHU Pontchaillou, Service de Neurochirurgie, Rennes (France)

    2012-11-15

    Diffusion tensor imaging and tractography allow studying white matter fiber bundles in the human brain in vivo. Electrophysiological studies and postmortem dissections permit improving our knowledge about the short association fibers connecting the pre- and postcentral gyri. The aim of this study was first to extract and analyze the features of these short fiber bundles and secondly to analyze their asymmetry according to the subjects' handedness. Ten right-handed and ten left-handed healthy subjects were included. White matter fiber bundles were extracted using a streamline tractography approach, with two seed regions of interest (ROI) taken from a parcellation of the pre- and postcentral gyri. This parcellation was achieved using T1 magnetic resonance images (MRI) and semi-automatically generated three ROIs within each gyrus. MRI tracks were reconstructed between all pairs of ROIs connecting the adjacent pre- and postcentral gyri. A quantitative analysis was performed on the number of tracks connecting each ROI pair. A statistical analysis studied the repartition of these MRI tracks in the right and left hemispheres and as a function of the subjects' handedness. The quantitative analysis showed an increased density of MRI tracks in the middle part of the central area in each hemisphere of the 20 subjects. The statistical analysis showed significantly more MRI tracks for the left hemisphere, when we consider the whole population, and this difference was presumably driven by the left-handers. These results raise questions about the functional role of these MRI tracks and their relation with laterality. (orig.)

  2. High-resolution whole-brain diffusion MRI at 7T using radiofrequency parallel transmission.

    Science.gov (United States)

    Wu, Xiaoping; Auerbach, Edward J; Vu, An T; Moeller, Steen; Lenglet, Christophe; Schmitter, Sebastian; Van de Moortele, Pierre-François; Yacoub, Essa; Uğurbil, Kâmil

    2018-03-30

    Investigating the utility of RF parallel transmission (pTx) for Human Connectome Project (HCP)-style whole-brain diffusion MRI (dMRI) data at 7 Tesla (7T). Healthy subjects were scanned in pTx and single-transmit (1Tx) modes. Multiband (MB), single-spoke pTx pulses were designed to image sagittal slices. HCP-style dMRI data (i.e., 1.05-mm resolutions, MB2, b-values = 1000/2000 s/mm 2 , 286 images and 40-min scan) and data with higher accelerations (MB3 and MB4) were acquired with pTx. pTx significantly improved flip-angle detected signal uniformity across the brain, yielding ∼19% increase in temporal SNR (tSNR) averaged over the brain relative to 1Tx. This allowed significantly enhanced estimation of multiple fiber orientations (with ∼21% decrease in dispersion) in HCP-style 7T dMRI datasets. Additionally, pTx pulses achieved substantially lower power deposition, permitting higher accelerations, enabling collection of the same data in 2/3 and 1/2 the scan time or of more data in the same scan time. pTx provides a solution to two major limitations for slice-accelerated high-resolution whole-brain dMRI at 7T; it improves flip-angle uniformity, and enables higher slice acceleration relative to current state-of-the-art. As such, pTx provides significant advantages for rapid acquisition of high-quality, high-resolution truly whole-brain dMRI data. © 2018 International Society for Magnetic Resonance in Medicine.

  3. Brain MRI diffusion-weighted imaging in patients with classical phenylketonuria

    International Nuclear Information System (INIS)

    Manara, Renzo; Citton, Valentina; Carollo, Carla; Burlina, Alessandro P.; Ermani, Mario; Vespignani, Francesco; Burlina, Alberto B.

    2009-01-01

    The aim of this study was to grade magnetic resonance white matter abnormalities (WMAs) of classical phenylketonuria (cPKU) patients treated from birth and to compare sensitivity and specificity of T2-weighted and diffusion-weighted images (DWI). Twenty early-treated cPKU patients still on a low-phenylalanine diet (12 males; mean age 21.2 years) and 26 normal subjects (ten males; mean age 25.1 years) were enrolled. Typical T2- and diffusion-weighted WMAs were semiquantitatively graded according to Thompson score (TS). Besides, a regional magnetic resonance imaging (MRI) score (mTS) was developed according to extension and intensity of WMAs. Phenylalanine and tyrosine plasma concentrations before performing MRI and the amino acid mean levels collected the year before MRI (Tyr year and Phe year ) were measured. No patient with Phe year concentration below 460 μmol/L showed WMAs. In cPKU patients, TS and mTS were significantly higher on DWI than on T2 images (3.50 vs 2.65 and 23.65 vs 15.85, respectively, p year levels. Among the different MR sequences, DWI seems to be the most sensitive and reliable in detecting and grading the typical WMAs of cPKU patients. (orig.)

  4. Diffusion MRI for rectal cancer staging: ADC measurements before and after ultrasonographic gel lumen distension

    Energy Technology Data Exchange (ETDEWEB)

    Palmucci, S., E-mail: spalmucci@sirm.org; Piccoli, M.; Piana, S.; Foti, P.V.; Siverino, R.O.A.; Mauro, L.A.; Milone, P.; Ettorre, G.C.

    2017-01-15

    Objectives: To compare Apparent Diffusion Coefficient (ADC) measurements in rectal neoplastic lesions before and after lumen distension obtained with sonography transmission gel. Methods: From January 2014 to July 2016, 25 patients (average age 63.7, range 41–85, 18 males) were studied for pre-treatment rectal cancer staging using a 1.5 T MRI. Diffusion MRI was obtained using echo-planar imaging with b = 800 value; all patients were studied acquiring diffusion sequences with and without rectal lumen distension obtained using sonography transmission gel. In both diffusion sequences, two blinded readers calculated border ADC values and small ADC values, drawing regions of interest respectively along tumour borders and far from tumour borders. Mean ADC values among readers − for each type of ADC measurement − were compared using Wilcoxon matched pairs signed rank test. Correlation was assessed using Pearson analysis. Results: Border ADC mean value for diffusion MR sequences without endorectal contrast was 1.122 mm{sup 2}/sec, with 95% Confidence Interval (CI) = 1.02–1.22; using gel lumen distension, higher border ADC mean value of 1.269 mm{sup 2}/s (95% CI = 1.16–1.38) was obtained. Wilcoxon matched pairs signed rank test revealed statistical difference (p < 0.01); a strong Pearson correlation was reported, with r value of 0.69. Small-ADC mean value was 1.038 mm{sup 2}/s (95% CI = 0.91–1.16) for diffusion sequences acquired without endorectal distension and 1.127 mm{sup 2}/s (95% CI = 0.98–1.27) for diffusion sequences obtained after endorectal gel lumen distension. Wilcoxon analysis did not show statistical difference (p = 0.13). A very strong positive correlation was observed, with r value of 0.81. Conclusions: ADC measurements are slightly higher using endorectal sonographic transmission gel; ROI should be traced far from tumour borders, to minimize gel filled-pixel along the interface between lumen and lesion. Further studies are needed to

  5. Diffusion MRI for rectal cancer staging: ADC measurements before and after ultrasonographic gel lumen distension

    International Nuclear Information System (INIS)

    Palmucci, S.; Piccoli, M.; Piana, S.; Foti, P.V.; Siverino, R.O.A.; Mauro, L.A.; Milone, P.; Ettorre, G.C.

    2017-01-01

    Objectives: To compare Apparent Diffusion Coefficient (ADC) measurements in rectal neoplastic lesions before and after lumen distension obtained with sonography transmission gel. Methods: From January 2014 to July 2016, 25 patients (average age 63.7, range 41–85, 18 males) were studied for pre-treatment rectal cancer staging using a 1.5 T MRI. Diffusion MRI was obtained using echo-planar imaging with b = 800 value; all patients were studied acquiring diffusion sequences with and without rectal lumen distension obtained using sonography transmission gel. In both diffusion sequences, two blinded readers calculated border ADC values and small ADC values, drawing regions of interest respectively along tumour borders and far from tumour borders. Mean ADC values among readers − for each type of ADC measurement − were compared using Wilcoxon matched pairs signed rank test. Correlation was assessed using Pearson analysis. Results: Border ADC mean value for diffusion MR sequences without endorectal contrast was 1.122 mm 2 /sec, with 95% Confidence Interval (CI) = 1.02–1.22; using gel lumen distension, higher border ADC mean value of 1.269 mm 2 /s (95% CI = 1.16–1.38) was obtained. Wilcoxon matched pairs signed rank test revealed statistical difference (p < 0.01); a strong Pearson correlation was reported, with r value of 0.69. Small-ADC mean value was 1.038 mm 2 /s (95% CI = 0.91–1.16) for diffusion sequences acquired without endorectal distension and 1.127 mm 2 /s (95% CI = 0.98–1.27) for diffusion sequences obtained after endorectal gel lumen distension. Wilcoxon analysis did not show statistical difference (p = 0.13). A very strong positive correlation was observed, with r value of 0.81. Conclusions: ADC measurements are slightly higher using endorectal sonographic transmission gel; ROI should be traced far from tumour borders, to minimize gel filled-pixel along the interface between lumen and lesion. Further studies are needed to investigate better

  6. Persistent lesion hyperintensity on brain diffusion-weighted MRI is an early sign of intravascular lymphoma.

    Science.gov (United States)

    Kageyama, Takashi; Yamanaka, Haruo; Nakamura, Fumihiko; Suenaga, Toshihiko

    2017-06-08

    A 63-year-old man presented with right-sided hemianopia and unsteady gait. Brain MRI revealed multiple hyperintense infarct-like lesions on diffusion-weighted images (DWI). Hyperintensity persisted in some of these lesions even after 6 weeks, although his symptoms were ameliorated then. The patient developed episodic dizziness and a transient event of apraxia at 18 weeks after the first episode. Brain MRI revealed additional hyperintense lesions on DWI, which persisted even after 7 weeks. Eventually, the patient manifested cauda equina syndrome 39 weeks after the first episode. Brain MRI showed the presence of new lesions in addition to the persistent hyperintense lesions on DWI over 21 weeks in the right frontal lobe. Based on laboratory findings and the pathological assessment of bone marrow and random skin biopsies, the patient was diagnosed with intravascular lymphoma (IVL). Persistent hyperintense lesions on DWI of brain MRI may precede the clinical exacerbation of IVL. © BMJ Publishing Group Ltd (unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

  7. Quantifying diffusion MRI tractography of the corticospinal tract in brain tumors with deterministic and probabilistic methods.

    Science.gov (United States)

    Bucci, Monica; Mandelli, Maria Luisa; Berman, Jeffrey I; Amirbekian, Bagrat; Nguyen, Christopher; Berger, Mitchel S; Henry, Roland G

    2013-01-01

    Diffusion MRI tractography has been increasingly used to delineate white matter pathways in vivo for which the leading clinical application is presurgical mapping of eloquent regions. However, there is rare opportunity to quantify the accuracy or sensitivity of these approaches to delineate white matter fiber pathways in vivo due to the lack of a gold standard. Intraoperative electrical stimulation (IES) provides a gold standard for the location and existence of functional motor pathways that can be used to determine the accuracy and sensitivity of fiber tracking algorithms. In this study we used intraoperative stimulation from brain tumor patients as a gold standard to estimate the sensitivity and accuracy of diffusion tensor MRI (DTI) and q-ball models of diffusion with deterministic and probabilistic fiber tracking algorithms for delineation of motor pathways. We used preoperative high angular resolution diffusion MRI (HARDI) data (55 directions, b = 2000 s/mm(2)) acquired in a clinically feasible time frame from 12 patients who underwent a craniotomy for resection of a cerebral glioma. The corticospinal fiber tracts were delineated with DTI and q-ball models using deterministic and probabilistic algorithms. We used cortical and white matter IES sites as a gold standard for the presence and location of functional motor pathways. Sensitivity was defined as the true positive rate of delineating fiber pathways based on cortical IES stimulation sites. For accuracy and precision of the course of the fiber tracts, we measured the distance between the subcortical stimulation sites and the tractography result. Positive predictive rate of the delineated tracts was assessed by comparison of subcortical IES motor function (upper extremity, lower extremity, face) with the connection of the tractography pathway in the motor cortex. We obtained 21 cortical and 8 subcortical IES sites from intraoperative mapping of motor pathways. Probabilistic q-ball had the best

  8. Automatic classification of patients with idiopathic Parkinson's disease and progressive supranuclear palsy using diffusion MRI datasets

    Science.gov (United States)

    Talai, Sahand; Boelmans, Kai; Sedlacik, Jan; Forkert, Nils D.

    2017-03-01

    Parkinsonian syndromes encompass a spectrum of neurodegenerative diseases, which can be classified into various subtypes. The differentiation of these subtypes is typically conducted based on clinical criteria. Due to the overlap of intra-syndrome symptoms, the accurate differential diagnosis based on clinical guidelines remains a challenge with failure rates up to 25%. The aim of this study is to present an image-based classification method of patients with Parkinson's disease (PD) and patients with progressive supranuclear palsy (PSP), an atypical variant of PD. Therefore, apparent diffusion coefficient (ADC) parameter maps were calculated based on diffusion-tensor magnetic resonance imaging (MRI) datasets. Mean ADC values were determined in 82 brain regions using an atlas-based approach. The extracted mean ADC values for each patient were then used as features for classification using a linear kernel support vector machine classifier. To increase the classification accuracy, a feature selection was performed, which resulted in the top 17 attributes to be used as the final input features. A leave-one-out cross validation based on 56 PD and 21 PSP subjects revealed that the proposed method is capable of differentiating PD and PSP patients with an accuracy of 94.8%. In conclusion, the classification of PD and PSP patients based on ADC features obtained from diffusion MRI datasets is a promising new approach for the differentiation of Parkinsonian syndromes in the broader context of decision support systems.

  9. Spectral Analysis of Non-ideal MRI Modes: The Effect of Hall Diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Mohandas, Gopakumar; Pessah, Martin E., E-mail: gopakumar@nbi.ku.dk, E-mail: mpessah@nbi.ku.dk [Niels Bohr International Academy, Niels Bohr Institute, Blegdamsvej 17, DK-2100, Copenhagen Ø (Denmark)

    2017-03-20

    The effect of magnetic field diffusion on the stability of accretion disks is a problem that has attracted considerable interest of late. In particular, the Hall effect has the potential to bring about remarkable changes in the dynamical behavior of disks that are without parallel. In this paper, we conduct a systematic examination of the linear eigenmodes in a weakly magnetized differentially rotating gas with a special focus on Hall diffusion. We first develop a geometrical representation of the eigenmodes and provide a detailed quantitative description of the polarization properties of the oscillatory modes under the combined influence of the Coriolis and Hall effects. We also analyze the effects of magnetic diffusion on the structure of the unstable modes and derive analytical expressions for the kinetic and magnetic stresses and energy densities associated with the non-ideal magnetorotational instability (MRI). Our analysis explicitly demonstrates that, if the dissipative effects are relatively weak, the kinetic stresses and energies make up the dominant contribution to the total stress and energy density when the equilibrium angular momentum and magnetic field vectors are anti-parallel. This is in sharp contrast to what is observed in the case of the ideal or dissipative MRI. We conduct shearing box simulations and find very good agreement with the results derived from linear theory. Because the modes under consideration are also exact solutions of the nonlinear equations, the unconventional nature of the kinetic and magnetic stresses may have significant implications for the nonlinear evolution in some regions of protoplanetary disks.

  10. Diffusion-weighted MRI characteristics of the cerebral metastasis to brain boundary predicts patient outcomes

    International Nuclear Information System (INIS)

    Zakaria, Rasheed; Das, Kumar; Radon, Mark; Bhojak, Maneesh; Rudland, Philip R; Sluming, Vanessa; Jenkinson, Michael D

    2014-01-01

    Diffusion-weighted MRI (DWI) has been used in neurosurgical practice mainly to distinguish cerebral metastases from abscess and glioma. There is evidence from other solid organ cancers and metastases that DWI may be used as a biomarker of prognosis and treatment response. We therefore investigated DWI characteristics of cerebral metastases and their peritumoral region recorded pre-operatively and related these to patient outcomes. Retrospective analysis of 76 cases operated upon at a single institution with DWI performed pre-operatively at 1.5T. Maps of apparent diffusion coefficient (ADC) were generated using standard protocols. Readings were taken from the tumor, peritumoral region and across the brain-tumor interface. Patient outcomes were overall survival and time to local recurrence. A minimum ADC greater than 919.4 × 10 -6 mm 2 /s within a metastasis predicted longer overall survival regardless of adjuvant therapies. This was not simply due to differences between the types of primary cancer because the effect was observed even in a subgroup of 36 patients with the same primary, non-small cell lung cancer. The change in diffusion across the tumor border and into peritumoral brain was measured by the “ADC transition coefficient” or ATC and this was more strongly predictive than ADC readings alone. Metastases with a sharp change in diffusion across their border (ATC >0.279) showed shorter overall survival compared to those with a more diffuse edge. The ATC was the only imaging measurement which independently predicted overall survival in multivariate analysis (hazard ratio 0.54, 95% CI 0.3 – 0.97, p = 0.04). DWI demonstrates changes in the tumor, across the tumor edge and in the peritumoral region which may not be visible on conventional MRI and this may be useful in predicting patient outcomes for operated cerebral metastases

  11. Diffusion-weighted MRI of kidneys in healthy volunteers and living kidney donors

    International Nuclear Information System (INIS)

    Sulkowska, K.; Palczewski, P.; Duda-Zysk, A.; Szeszkowski, W.; Wojcik, D.; Kownacka-Piotrowska, D.; Gołebiowski, M.

    2015-01-01

    Aim: To establish the normal apparent diffusion coefficient (ADC) values in healthy kidneys, comparing them with the literature, and assessing the correlation between ADC values, creatinine blood level, and glomerular filtration rate (GFR). Materials and methods: Twenty-four healthy volunteers and 26 living kidney donors were examined on a 1.5 T magnetic resonance imaging (MRI) unit. Two diffusion-weighted imaging (DWI) sequences were included in the study protocol (protocol 1 with 16 b-values, protocol 2 with 10 b-values) before the examination blood and urine samples were collected. The GFR was calculated using Cockcroft & Gault and MDRD (Modification of Diet In Renal Disease) formulas and the ADC values were measured separately for the cortex and medulla of each kidney by two independent observers. All statistical analyses were performed using the STATISTICA (version 10.0) software package. Data were analysed using an unpaired t-test; p<0.05 indicated a statistically significant difference. Results: The average ADC value for protocol 1 for the cortex was 2.26×10 −3  mm 2 /s, for the medulla 2.21×10 −3  mm 2 /s. In protocol 2, the respective values were 2.13×10 −3  mm 2 /s and 2.06×10 −3  mm 2 /s. Neither statistically significant interobserver differences nor correlation between ADC values, GFR, and creatinine serum level were observed. Conclusion: The reference ADC values were established. The measurements show high interobserver consistency. The differences in ADC values reported in the literature suggest dependence on the equipment and methodology and point to the necessity of obtaining ADC norms for each MRI unit. -- Highlights: •Magnetic resonance diffusion-weighted imaging of kidneys. •Apparent diffusion coefficient in healthy individuals. •Monoexponential model of diffusion

  12. Diffusion- and perfusion-weighted MRI in a patient with a prolonged reversible ischaemic neurological deficit

    International Nuclear Information System (INIS)

    Neumann-Haefelin, T.; Wittsack, H.J.; Wenserski, F.; Li, T.Q.; Moseley, M.E.; Siebler, M.; Freund, H.J.

    2000-01-01

    We report acute and follow-up diffusion- and perfusion-weighted MRI (DWI, PWI) findings in a patient with a prolonged reversible ischaemic neurological deficit. PWI 12 h after the patient was last seen to be without symptoms revealed a large perfusion deficit in the left posterior MCA territory with a relatively inconspicuous and much smaller abnormality on DWI. Follow-up showed resolution of abnormalities on both DWI and PWI, and conventional MRI was normal, apart from a very slight abnormality, visible only on FLAIR images, at the centre of the initially DWI-positive region. These findings demonstrate the utility of PWI when be used in combination with DWI to investigate the pathophysiology of transient ischemic syndromes. (orig.)

  13. Transient detection of early wallerian degeneration on diffusion-weighted MRI after an acute cerebrovascular accident

    International Nuclear Information System (INIS)

    Uchino, A.; Sawada, A.; Takase, Y.; Egashira, R.; Kudo, S.

    2004-01-01

    We report three patients with a cerebrovascular accident studied serially by MRI, including diffusion-weighted imaging (DWI). In case 1, DWI 1 day after the onset of left frontoparietal cortical infarcts showed no abnormal signal in the left corticospinal tract. DWI 12 days after onset showed high signal in the corticospinal tract, interpreted as early wallerian degeneration. This had disappeared by 22 days after onset. In case 2, DWI obtained 7 days after the onset of a right internal capsule lacunar infarct showed high signal from the right corticospinal tract in the brainstem, which was less marked 15 days after onset. In case 3, MRI on postnatal day 7 showed a cerebral haemorrhage in the right corona radiata and high signal from the right corticospinal tract on DWI. The latter disappeared by day 23. DWI shows early wallerian degeneration; transient signal abnormalities within 2 weeks of stroke should not be mistaken for new ischaemic lesions. (orig.)

  14. Diffusion-weighted imaging (DWI) in musculoskeletal MRI: a critical review

    Energy Technology Data Exchange (ETDEWEB)

    Khoo, Michael M.Y.; Tyler, Philippa A.; Saifuddin, Asif [Royal National Orthopaedic Hospital, Department of Radiology, Stanmore, Middlesex (United Kingdom); Padhani, Anwar R. [Mount Vernon Cancer Centre, Paul Strickland Scanner Centre, Northwood (United Kingdom)

    2011-06-15

    Magnetic resonance imaging (MRI) is the mainstay of diagnosis, staging and follow-up of much musculoskeletal pathology. Diffusion-weighted magnetic resonance imaging (DWI) is a recent addition to the MR sequences conventionally employed. DWI provides qualitative and quantitative functional information concerning the microscopic movements of water at the cellular level. A number of musculoskeletal disorders have been evaluated by DWI, including vertebral fractures, bone marrow infection, bone marrow malignancy, primary bone and soft tissue tumours; post-treatment follow-up has also been assessed. Differentiation between benign and malignant vertebral fractures by DWI and monitoring of therapy response have shown excellent results. However, in other pathologies, such as primary soft tissue tumours, DWI data have been inconclusive in some cases, contributing little additional information beyond that gained from conventional MR sequences. The aim of this article is to critically review the current literature on the contribution of DWI to musculoskeletal MRI. (orig.)

  15. Transient detection of early wallerian degeneration on diffusion-weighted MRI after an acute cerebrovascular accident

    Energy Technology Data Exchange (ETDEWEB)

    Uchino, A.; Sawada, A.; Takase, Y.; Egashira, R.; Kudo, S. [Department of Radiology, Saga Medical School, 5-1-1 Nabeshima, Saga, 849-8501 (Japan)

    2004-03-01

    We report three patients with a cerebrovascular accident studied serially by MRI, including diffusion-weighted imaging (DWI). In case 1, DWI 1 day after the onset of left frontoparietal cortical infarcts showed no abnormal signal in the left corticospinal tract. DWI 12 days after onset showed high signal in the corticospinal tract, interpreted as early wallerian degeneration. This had disappeared by 22 days after onset. In case 2, DWI obtained 7 days after the onset of a right internal capsule lacunar infarct showed high signal from the right corticospinal tract in the brainstem, which was less marked 15 days after onset. In case 3, MRI on postnatal day 7 showed a cerebral haemorrhage in the right corona radiata and high signal from the right corticospinal tract on DWI. The latter disappeared by day 23. DWI shows early wallerian degeneration; transient signal abnormalities within 2 weeks of stroke should not be mistaken for new ischaemic lesions. (orig.)

  16. ON INTERSECTIONS OF INDEPENDENT NONDEGENERATE DIFFUSION PROCESSES

    Institute of Scientific and Technical Information of China (English)

    Zhenlong CHEN

    2014-01-01

    Let X(1) = {X(1)(s), s ∈ R+} and X(2) = {X(2)(t), t ∈ R+} be two inde-pendent nondegenerate diffusion processes with values in Rd. The existence and fractal dimension of intersections of the sample paths of X (1) and X (2) are studied. More gener-ally, let E1, E2⊆(0,∞) and F ⊂Rd be Borel sets. A necessary condition and a suffcient condition for P{X(1)(E1)∩X(2)(E2)∩F 6=∅}>0 are proved in terms of the Bessel-Riesz type capacity and Hausdorff measure of E1 × E2 × F in the metric space (R+× R+× Rd,ρb), whereρb is an unsymmetric metric defined in R+× R+× Rd. Under reasonable conditions, results resembling those of Browian motion are obtained.

  17. Comparison of non-Gaussian and Gaussian diffusion models of diffusion weighted imaging of rectal cancer at 3.0 T MRI.

    Science.gov (United States)

    Zhang, Guangwen; Wang, Shuangshuang; Wen, Didi; Zhang, Jing; Wei, Xiaocheng; Ma, Wanling; Zhao, Weiwei; Wang, Mian; Wu, Guosheng; Zhang, Jinsong

    2016-12-09

    Water molecular diffusion in vivo tissue is much more complicated. We aimed to compare non-Gaussian diffusion models of diffusion-weighted imaging (DWI) including intra-voxel incoherent motion (IVIM), stretched-exponential model (SEM) and Gaussian diffusion model at 3.0 T MRI in patients with rectal cancer, and to determine the optimal model for investigating the water diffusion properties and characterization of rectal carcinoma. Fifty-nine consecutive patients with pathologically confirmed rectal adenocarcinoma underwent DWI with 16 b-values at a 3.0 T MRI system. DWI signals were fitted to the mono-exponential and non-Gaussian diffusion models (IVIM-mono, IVIM-bi and SEM) on primary tumor and adjacent normal rectal tissue. Parameters of standard apparent diffusion coefficient (ADC), slow- and fast-ADC, fraction of fast ADC (f), α value and distributed diffusion coefficient (DDC) were generated and compared between the tumor and normal tissues. The SEM exhibited the best fitting results of actual DWI signal in rectal cancer and the normal rectal wall (R 2  = 0.998, 0.999 respectively). The DDC achieved relatively high area under the curve (AUC = 0.980) in differentiating tumor from normal rectal wall. Non-Gaussian diffusion models could assess tissue properties more accurately than the ADC derived Gaussian diffusion model. SEM may be used as a potential optimal model for characterization of rectal cancer.

  18. Single-shot spiral imaging enabled by an expanded encoding model: Demonstration in diffusion MRI.

    Science.gov (United States)

    Wilm, Bertram J; Barmet, Christoph; Gross, Simon; Kasper, Lars; Vannesjo, S Johanna; Haeberlin, Max; Dietrich, Benjamin E; Brunner, David O; Schmid, Thomas; Pruessmann, Klaas P

    2017-01-01

    The purpose of this work was to improve the quality of single-shot spiral MRI and demonstrate its application for diffusion-weighted imaging. Image formation is based on an expanded encoding model that accounts for dynamic magnetic fields up to third order in space, nonuniform static B 0 , and coil sensitivity encoding. The encoding model is determined by B 0 mapping, sensitivity mapping, and concurrent field monitoring. Reconstruction is performed by iterative inversion of the expanded signal equations. Diffusion-tensor imaging with single-shot spiral readouts is performed in a phantom and in vivo, using a clinical 3T instrument. Image quality is assessed in terms of artefact levels, image congruence, and the influence of the different encoding factors. Using the full encoding model, diffusion-weighted single-shot spiral imaging of high quality is accomplished both in vitro and in vivo. Accounting for actual field dynamics, including higher orders, is found to be critical to suppress blurring, aliasing, and distortion. Enhanced image congruence permitted data fusion and diffusion tensor analysis without coregistration. Use of an expanded signal model largely overcomes the traditional vulnerability of spiral imaging with long readouts. It renders single-shot spirals competitive with echo-planar readouts and thus deploys shorter echo times and superior readout efficiency for diffusion imaging and further prospective applications. Magn Reson Med 77:83-91, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

  19. Function-specific and Enhanced Brain Structural Connectivity Mapping via Joint Modeling of Diffusion and Functional MRI.

    Science.gov (United States)

    Chu, Shu-Hsien; Parhi, Keshab K; Lenglet, Christophe

    2018-03-16

    A joint structural-functional brain network model is presented, which enables the discovery of function-specific brain circuits, and recovers structural connections that are under-estimated by diffusion MRI (dMRI). Incorporating information from functional MRI (fMRI) into diffusion MRI to estimate brain circuits is a challenging task. Usually, seed regions for tractography are selected from fMRI activation maps to extract the white matter pathways of interest. The proposed method jointly analyzes whole brain dMRI and fMRI data, allowing the estimation of complete function-specific structural networks instead of interactively investigating the connectivity of individual cortical/sub-cortical areas. Additionally, tractography techniques are prone to limitations, which can result in erroneous pathways. The proposed framework explicitly models the interactions between structural and functional connectivity measures thereby improving anatomical circuit estimation. Results on Human Connectome Project (HCP) data demonstrate the benefits of the approach by successfully identifying function-specific anatomical circuits, such as the language and resting-state networks. In contrast to correlation-based or independent component analysis (ICA) functional connectivity mapping, detailed anatomical connectivity patterns are revealed for each functional module. Results on a phantom (Fibercup) also indicate improvements in structural connectivity mapping by rejecting false-positive connections with insufficient support from fMRI, and enhancing under-estimated connectivity with strong functional correlation.

  20. Diffusion-weighted MRI of the prostate; Diffusionsgewichtete MRT der Prostata

    Energy Technology Data Exchange (ETDEWEB)

    Mueller-Lisse, U.G.; Scherr, M.K. [Klinikum der Ludwig-Maximilians-Universitaet Muenchen, Institut fuer Klinische Radiologie, Muenchen (Germany); Mueller-Lisse, U.L. [Klinikum der Ludwig-Maximilians-Universitaet Muenchen, Klinik und Poliklinik fuer Urologie, Muenchen (Germany); Zamecnik, P.; Schlemmer, H.P.W. [Deutsches Krebsforschungszentrum (DKFZ), Abteilung fuer Radiologische Diagnostik, Heidelberg (Germany)

    2011-03-15

    Diffusion-weighted magnetic resonance imaging (DWI) can complement MRI of the prostate in the detection and localization of prostate cancer, particularly after previous negative biopsy. A total of 13 original reports and 2 reviews published in 2010 demonstrate that prostate cancer can be detected by DWI due to its increased cell density and decreased diffusiveness, either qualitatively in DWI images or quantitatively by means of the apparent diffusion coefficient (ADC). In the prostate, the ADC is influenced by the strength of diffusion weighting, localization (peripheral or transitional zone), presence of prostatitis or hemorrhage and density and differentiation of prostate cancer cells. Mean differences between healthy tissue of the peripheral zone and prostate cancer appear to be smaller for ADC than for the (choline + creatine)/citrate ratio in MR spectroscopy. Test quality parameters vary greatly between different studies but appear to be slightly better for combined MRI and DWI than for MRI of the prostate alone. Clinical validation of DWI of the prostate requires both increased technical conformity and increased numbers of patients in clinical studies. (orig.) [German] Die diffusionsgewichtete MRT (''diffusion-weighted imaging'', DWI) kann die MRT der Prostata bei der Erkennung und Lokalisation von Prostatakarzinomen besonders nach vorangehender, negativer Stanzbiopsie ergaenzen. In 13 klinischen Original- und 2 Uebersichtsarbeiten des Jahres 2010 zeigt sich, dass die DWI Prostatakarzinome an Einschraenkungen der freien Teilchenbeweglichkeit bei erhoehter Zelldichte qualitativ im Bild oder quantitativ an Hand des ''apparent diffusion coefficient'' (ADC) nachweist. Den ADC in der Prostata beeinflussen Staerke der Diffusionsgewichtung, Lokalisation (periphere Zone, Transitionalzone), Vorliegen von Prostatitis oder Einblutung sowie Streudichte und Differenzierung von Prostatakarzinomzellen. Unterschiede zwischen gesundem

  1. Support vector machine for breast cancer classification using diffusion-weighted MRI histogram features: Preliminary study.

    Science.gov (United States)

    Vidić, Igor; Egnell, Liv; Jerome, Neil P; Teruel, Jose R; Sjøbakk, Torill E; Østlie, Agnes; Fjøsne, Hans E; Bathen, Tone F; Goa, Pål Erik

    2018-05-01

    Diffusion-weighted MRI (DWI) is currently one of the fastest developing MRI-based techniques in oncology. Histogram properties from model fitting of DWI are useful features for differentiation of lesions, and classification can potentially be improved by machine learning. To evaluate classification of malignant and benign tumors and breast cancer subtypes using support vector machine (SVM). Prospective. Fifty-one patients with benign (n = 23) and malignant (n = 28) breast tumors (26 ER+, whereof six were HER2+). Patients were imaged with DW-MRI (3T) using twice refocused spin-echo echo-planar imaging with echo time / repetition time (TR/TE) = 9000/86 msec, 90 × 90 matrix size, 2 × 2 mm in-plane resolution, 2.5 mm slice thickness, and 13 b-values. Apparent diffusion coefficient (ADC), relative enhanced diffusivity (RED), and the intravoxel incoherent motion (IVIM) parameters diffusivity (D), pseudo-diffusivity (D*), and perfusion fraction (f) were calculated. The histogram properties (median, mean, standard deviation, skewness, kurtosis) were used as features in SVM (10-fold cross-validation) for differentiation of lesions and subtyping. Accuracies of the SVM classifications were calculated to find the combination of features with highest prediction accuracy. Mann-Whitney tests were performed for univariate comparisons. For benign versus malignant tumors, univariate analysis found 11 histogram properties to be significant differentiators. Using SVM, the highest accuracy (0.96) was achieved from a single feature (mean of RED), or from three feature combinations of IVIM or ADC. Combining features from all models gave perfect classification. No single feature predicted HER2 status of ER + tumors (univariate or SVM), although high accuracy (0.90) was achieved with SVM combining several features. Importantly, these features had to include higher-order statistics (kurtosis and skewness), indicating the importance to account for heterogeneity. Our

  2. Whole-body MRI for full assessment and characterization of diffuse inflammatory myopathy

    Directory of Open Access Journals (Sweden)

    Saleh Saleh Elessawy

    2016-09-01

    Full Text Available Background Conventional magnetic resonance imaging (MRI is a highly valuable tool for full assessment of the extent of bilateral symmetrical diffuse inflammatory myopathy, owing to its high sensitivity in the detection of edema which correlates with, and sometimes precedes, clinical findings. Purpose To evaluate the use of whole-body (WB-MRI in characterization and full assessment of the extent and distribution of diffuse inflammatory myopathy. Material and Methods A prospective study on 15 patients presenting with clinical evidence of inflammatory myopathy. It included 4 boys/men and 11 girls/women (age range, 6–44 years; mean age, 25.5 years. 1.5 T WB-MRI was performed and the distribution and extent of disease severity was assessed according to muscle edema on STIR images. Results Four cases of dermatomyositis showed lower limb disease predilection with edema in gluteal, thigh, and calf muscles. The same finding was seen in one case with recurrent polymyositis and three cases with overlap myositis with systemic lupus erythematosus (SLE. Bilateral upper and lower limb myositis was demonstrated in three cases of polymyositis and one case of overlap myositis with scleroderma. Bilateral edema involving all scanned muscle groups was detected in three cases of polymyositis with paraneoplastic syndrome, SLE, and severe active dermatomyositis (including the neck muscles. Conclusion WB-MRI is the diagnostic modality of choice for cases of inflammatory myopathy. It accurately detects the most severely affected muscles candidate for biopsy and provides a reliable baseline study for follow-up of disease progression as well as response to treatment.

  3. Cortical hypoxic-ischemic brain damage in shaken-baby (shaken impact) syndrome: value of diffusion-weighted MRI

    International Nuclear Information System (INIS)

    Parizel, Paul M.; Oezsarlak, Oezkan; Goethem, Johan W. van; Ceulemans, Berten; Laridon, Annick; Jorens, Philippe G.

    2003-01-01

    Shaken-baby syndrome (SBS) is a type of child abuse caused by violent shaking of an infant, with or without impact, and characterized by subdural hematomas, retinal hemorrhages, and occult bone fractures. Parenchymal brain lesions in SBS may be missed or underestimated on CT scans, but can be detected at an earlier stage with diffusion-weighted MRI (DW-MRI) as areas of restricted diffusion. We demonstrate the value of DW-MRI in a 2-month-old baby boy with suspected SBS. The pattern of diffusion abnormalities indicates that the neuropathology of parenchymal lesions in SBS is due to hypoxic-ischemic brain injuries, and not to diffuse axonal injury. (orig.)

  4. Cortical hypoxic-ischemic brain damage in shaken-baby (shaken impact) syndrome: value of diffusion-weighted MRI

    Energy Technology Data Exchange (ETDEWEB)

    Parizel, Paul M.; Oezsarlak, Oezkan; Goethem, Johan W. van [Department of Radiology, University of Antwerp, Wilrijkstraat 10, 2650, Edegem (Belgium); Ceulemans, Berten; Laridon, Annick [Department of Pediatric Neurology, University of Antwerp, Wilrijkstraat 10, 2650, Edegem (Belgium); Jorens, Philippe G. [Department of Pediatric Intensive Care Medicine, University of Antwerp, Wilrijkstraat 10, 2650, Edegem (Belgium)

    2003-12-01

    Shaken-baby syndrome (SBS) is a type of child abuse caused by violent shaking of an infant, with or without impact, and characterized by subdural hematomas, retinal hemorrhages, and occult bone fractures. Parenchymal brain lesions in SBS may be missed or underestimated on CT scans, but can be detected at an earlier stage with diffusion-weighted MRI (DW-MRI) as areas of restricted diffusion. We demonstrate the value of DW-MRI in a 2-month-old baby boy with suspected SBS. The pattern of diffusion abnormalities indicates that the neuropathology of parenchymal lesions in SBS is due to hypoxic-ischemic brain injuries, and not to diffuse axonal injury. (orig.)

  5. Non-invasive imaging of transplanted human neural stem cells and ECM scaffold remodeling in the stroke-damaged rat brain by 19F- and diffusion-MRI

    Science.gov (United States)

    Bible, Ellen; Dell’Acqua, Flavio; Solanky, Bhavana; Balducci, Anthony; Crapo, Peter; Badylak, Stephen F.; Ahrens, Eric T.; Modo, Michel

    2012-01-01

    Transplantation of human neural stem cells (hNSCs) is emerging as a viable treatment for stroke related brain injury. However, intraparenchymal grafts do not regenerate lost tissue, but rather integrate into the host parenchyma without significantly affecting the lesion cavity. Providing a structural support for the delivered cells appears important for cell based therapeutic approaches. The non-invasive monitoring of therapeutic methods would provide valuable information regarding therapeutic strategies but remains a challenge. Labeling transplanted cells with metal-based 1H-magnetic resonance imaging (MRI) contrast agents affects the visualization of the lesion cavity. Herein, we demonstrate that a 19F-MRI contrast agent can adequately monitor the distribution of transplanted cells, whilst allowing an evaluation of the lesion cavity and the formation of new tissue on 1H-MRI scans. Twenty percent of cells labeled with the 19F-agent were of host origin, potentially reflecting the re-uptake of label from dead transplanted cells. Both T2- and diffusion-weighted MRI scans indicated that transplantation of hNSCs suspended in a gel form of a xenogeneic extracellular matrix (ECM) bioscaffold resulted in uniformly distributed cells throughout the lesion cavity. However, diffusion MRI indicated that the injected materials did not yet establish diffusion barriers (i.e. cellular network, fiber tracts) normally found within striatal tissue. The ECM bioscaffold therefore provides an important support to hNSCs for the creation of de novo tissue and multi-nuclei MRI represents an adept method for the visualization of some aspects of this process. However, significant developments of both the transplantation paradigm, as well as regenerative imaging, are required to successfully create new tissue in the lesion cavity and to monitor this process non-invasively. PMID:22244696

  6. Non-invasive imaging of transplanted human neural stem cells and ECM scaffold remodeling in the stroke-damaged rat brain by (19)F- and diffusion-MRI.

    Science.gov (United States)

    Bible, Ellen; Dell'Acqua, Flavio; Solanky, Bhavana; Balducci, Anthony; Crapo, Peter M; Badylak, Stephen F; Ahrens, Eric T; Modo, Michel

    2012-04-01

    Transplantation of human neural stem cells (hNSCs) is emerging as a viable treatment for stroke related brain injury. However, intraparenchymal grafts do not regenerate lost tissue, but rather integrate into the host parenchyma without significantly affecting the lesion cavity. Providing a structural support for the delivered cells appears important for cell based therapeutic approaches. The non-invasive monitoring of therapeutic methods would provide valuable information regarding therapeutic strategies but remains a challenge. Labeling transplanted cells with metal-based (1)H-magnetic resonance imaging (MRI) contrast agents affects the visualization of the lesion cavity. Herein, we demonstrate that a (19)F-MRI contrast agent can adequately monitor the distribution of transplanted cells, whilst allowing an evaluation of the lesion cavity and the formation of new tissue on (1)H-MRI scans. Twenty percent of cells labeled with the (19)F agent were of host origin, potentially reflecting the re-uptake of label from dead transplanted cells. Both T(2)- and diffusion-weighted MRI scans indicated that transplantation of hNSCs suspended in a gel form of a xenogeneic extracellular matrix (ECM) bioscaffold resulted in uniformly distributed cells throughout the lesion cavity. However, diffusion MRI indicated that the injected materials did not yet establish diffusion barriers (i.e. cellular network, fiber tracts) normally found within striatal tissue. The ECM bioscaffold therefore provides an important support to hNSCs for the creation of de novo tissue and multi-nuclei MRI represents an adept method for the visualization of some aspects of this process. However, significant developments of both the transplantation paradigm, as well as regenerative imaging, are required to successfully create new tissue in the lesion cavity and to monitor this process non-invasively. Copyright © 2011 Elsevier Ltd. All rights reserved.

  7. Monitoring In-Vivo the Mammary Gland Microstructure during Morphogenesis from Lactation to Post-Weaning Using Diffusion Tensor MRI.

    Science.gov (United States)

    Nissan, Noam; Furman-Haran, Edna; Shapiro-Feinberg, Myra; Grobgeld, Dov; Degani, Hadassa

    2017-09-01

    Lactation and the return to the pre-conception state during post-weaning are regulated by hormonal induced processes that modify the microstructure of the mammary gland, leading to changes in the features of the ductal / glandular tissue, the stroma and the fat tissue. These changes create a challenge in the radiological workup of breast disorder during lactation and early post-weaning. Here we present non-invasive MRI protocols designed to record in vivo high spatial resolution, T 2 -weighted images and diffusion tensor images of the entire mammary gland. Advanced imaging processing tools enabled tracking the changes in the anatomical and microstructural features of the mammary gland from the time of lactation to post-weaning. Specifically, by using diffusion tensor imaging (DTI) it was possible to quantitatively distinguish between the ductal / glandular tissue distention during lactation and the post-weaning involution. The application of the T 2 -weighted imaging and DTI is completely safe, non-invasive and uses intrinsic contrast based on differences in transverse relaxation rates and water diffusion rates in various directions, respectively. This study provides a basis for further in-vivo monitoring of changes during the mammary developmental stages, as well as identifying changes due to malignant transformation in patients with pregnancy associated breast cancer (PABC).

  8. Diffuse pachymeningeal enhancement on brain MRI: spontaneous intracranial hypotension and head trauma

    International Nuclear Information System (INIS)

    Ryu, Chang Woo; Lee, Byung Hee; Lee, Seung Ik; Kim, Young A; Kim, Hee Jin; Ko, Young Sik

    1998-01-01

    We evaluated the MRI finding of pachymeningeal enhancement in patients with intracranial hypotension and head trauma with particular attention to differential findings and change in follow-up study, and in order to support the knowledge about the pathophysiology of dural enhancement. The findings of enhanced brain MRI of fifteen patients who showed diffuse pachymeningeal enhancement were retrospectively examined. Seven of fifteen patients were finally diagnosed as spontaneous intracranial hypotension (SIH). Eight of fifteen patients had a recent history of head trauma. We analyzed the shape, thickness, continuity and extent of dural enhancement, and the others concerned with positive MR findings. We also analyzed findings suggested displacement of brain parenchyma-displacement of the iter and cerebellar tonsil, and flattening of the anterior aspect of the pons-. Four of seven patients with SIH and four of eight patients with head trauma, underwent follow-up MRI. In the follow-up study, the presence of resolving pachymeningeal enhancement and symptom improvement was investigated. In all cases of SIH, the dura showed diffuse, even 3(1mm thick, global and contiguous enhancement along both cerebral convexities, both tentoria, and the falx. Displacement of the iter was noted in six cases and flattening of the anterior aspect of the pons in five. Displacement of the cerebellar tonsil was noted in one case. Five of seven cases showed small amount of subdural fluid collection. In all cases of head trauma, the dura was enhanced diffusely and asymmetrically, and showed no contiguity. Its distribution was consistent with the locations of traumatic lesions. Displacement of the iter was noted in one case. In four cases of SIH, clinical symptoms had improved, and three showed complete resolution of dural enhancement, in one patient continuously showed partial dural enhancement. Four cases of head trauma showed complete resolution of dural enhancement. Reversible diffuse

  9. Apparent diffusion coefficient of vertebral haemangiomas allows differentiation from malignant focal deposits in whole-body diffusion-weighted MRI

    International Nuclear Information System (INIS)

    Winfield, Jessica M.; Blackledge, Matthew D.; Collins, David J.; Tunariu, Nina; Messiou, Christina; Poillucci, Gabriele; Shah, Vallari; Kaiser, Martin F.

    2018-01-01

    The aim of this study was to identify apparent diffusion coefficient (ADC) values for typical haemangiomas in the spine and to compare them with active malignant focal deposits. This was a retrospective single-institution study. Whole-body magnetic resonance imaging (MRI) scans of 106 successive patients with active multiple myeloma, metastatic prostate or breast cancer were analysed. ADC values of typical vertebral haemangiomas and malignant focal deposits were recorded. The ADC of haemangiomas (72 ROIs, median ADC 1,085 x 10 -6 mm 2 s -1 , interquartile range 927-1,295 x 10 -6 mm 2 s -1 ) was significantly higher than the ADC of malignant focal deposits (97 ROIs, median ADC 682 x 10 -6 mm 2 s -1 , interquartile range 583-781 x 10 -6 mm 2 s -1 ) with a p-value < 10 -6 . Receiver operating characteristic (ROC) analysis produced an area under the curve of 0.93. An ADC threshold of 872 x 10 -6 mm 2 s -1 separated haemangiomas from malignant focal deposits with a sensitivity of 84.7 % and specificity of 91.8 %. ADC values of classical vertebral haemangiomas are significantly higher than malignant focal deposits. The high ADC of vertebral haemangiomas allows them to be distinguished visually and quantitatively from active sites of disease, which show restricted diffusion. (orig.)

  10. Diffusion processes in nuclear waste glasses

    International Nuclear Information System (INIS)

    Serruys, Y.; Limoge, Y.; Brebec, G.

    1992-01-01

    Problems concerning the containment of nuclear wastes are presented. Different materials which have been considered for this purpose are briefly reviewed and we see why glass is one of the favorite candidates. It is focussed on what is known about diffusion in 'simple enough' glasses. After a recall concerning the structure and possible defects, the main results on diffusion in 'simple' glasses are given and it is shown what these results involve for the mechanisms of diffusion. The diffusion models are presented which can account for transport in random media: percolation and random walk models. Specific phenomena for the nuclear waste glasses are considered: the effect of irradiation on diffusion and leaching (i.e. corrosion by water). Finally diffusion data in nuclear waste glasses are presented. (author). 199 refs., 6 figs., 1 tab

  11. Added value of diffusion-weighted MRI in detection of cervical cancer recurrence: comparison with morphologic and dynamic contrast-enhanced MRI sequences.

    Science.gov (United States)

    Lucas, Rita; Lopes Dias, João; Cunha, Teresa Margarida

    2015-01-01

    We aimed to evaluate the added value of diffusion-weighted imaging (DWI) to standard magnetic resonance imaging (MRI) for detecting post-treatment cervical cancer recurrence. The detection accuracy of T2-weighted (T2W) images was compared with that of T2W MRI combined with either dynamic contrast-enhanced (DCE) MRI or DWI. Thirty-eight women with clinically suspected uterine cervical cancer recurrence more than six months after treatment completion were examined with 1.5 Tesla MRI including T2W, DCE, and DWI sequences. Disease was confirmed histologically and correlated with MRI findings. The diagnostic performance of T2W imaging and its combination with either DCE or DWI were analyzed. Sensitivity, positive predictive value, and accuracy were calculated. Thirty-six women had histologically proven recurrence. The accuracy for recurrence detection was 80% with T2W/DCE MRI and 92.1% with T2W/DWI. The addition of DCE sequences did not significantly improve the diagnostic ability of T2W imaging, and this sequence combination misclassified two patients as falsely positive and seven as falsely negative. The T2W/DWI combination revealed a positive predictive value of 100% and only three false negatives. The addition of DWI to T2W sequences considerably improved the diagnostic ability of MRI. Our results support the inclusion of DWI in the initial MRI protocol for the detection of cervical cancer recurrence, leaving DCE sequences as an option for uncertain cases.

  12. Apparent diffusion coefficients of normal uterus in premenopausal women with 3 T MRI

    International Nuclear Information System (INIS)

    Kuang, F.; Chen, Z.; Zhong, Q.; Fu, L.; Ma, M.

    2013-01-01

    Aim: To investigate the apparent diffusion coefficient (ADC) values of the normal uterine cervical zonal structures (cervical epithelium, the junctional zone, and myometrium) during different phases of the menstrual cycle among premenopausal women in different age groups. Materials and methods: Seventy healthy women, who were divided into three age groups (group A, 24 women in their twenties; group B, 23 women in their thirties; group C, 23 women in their forties), underwent 3 T magnetic resonance imaging (MRI) with T2-weighted and diffusion-weighted imaging (DWI) during the mid-proliferative and the mid-secretory phases. Results: The ADC values of each cervical zonal structure were significantly different from one another (p 0.05). Conclusion: ADC values of normal cervical epithelium and the junctional zone change with different phases of the menstrual cycle, which should be taken into consideration when early cervical disease is detected, when monitoring treatment response, and differentiating early tumour recurrence

  13. Arcuate fasciculus laterality by diffusion tensor imaging correlates with language laterality by functional MRI in preadolescent children

    International Nuclear Information System (INIS)

    Sreedharan, Ruma Madhu; Menon, Amitha C.; Thomas, Sanjeev V.; James, Jija S.; Kesavadas, Chandrasekharan

    2015-01-01

    Language lateralization is unique to humans. Functional MRI (fMRI) and diffusion tensor imaging (DTI) enable the study of language areas and white matter fibers involved in language, respectively. The objective of this study was to correlate arcuate fasciculus (AF) laterality by diffusion tensor imaging with that by fMRI in preadolescent children which has not yet been reported. Ten children between 8 and 12 years were subjected to fMRI and DTI imaging using Siemens 1.5 T MRI. Two language fMRI paradigms - visual verb generation and word pair task - were used. Analysis was done using SPM8 software. In DTI, the fiber volume of the arcuate fasciculus (AFV) and fractional anisotropy (FA) was measured. The fMRI Laterality Index (fMRI-LI) and DTI Laterality Index (DTI-LI) were calculated and their correlation assessed using the Pearson Correlation Index. Of ten children, mean age 10.6 years, eight showed left lateralization while bilateral language lateralization was seen in two. AFV by DTI was more on the left side in seven of the eight children who had left lateralization by fMRI. DTI could not trace the AF in one child. Of the two with bilateral language lateralization on fMRI, one showed larger AFV on the right side while the other did not show any asymmetry. There was a significant correlation (p < 0.02) between fMRI-LI and DTI-LI. Group mean of AFV by DTI was higher on the left side (2659.89 ± 654.75 mm 3 ) as compared to the right (1824.11 ± 582.81 mm 3 ) (p < 0.01). Like fMRI, DTI also reveals language laterality in children with a high degree of correlation between the two imaging modalities. (orig.)

  14. Arcuate fasciculus laterality by diffusion tensor imaging correlates with language laterality by functional MRI in preadolescent children

    Energy Technology Data Exchange (ETDEWEB)

    Sreedharan, Ruma Madhu [Government Medical College Hospital, Department of Radiology, Trivandrum, Kerala (India); Menon, Amitha C.; Thomas, Sanjeev V. [Sree Chitra, Thirunal Institute for Medical Sciences and Technology, Department of Neurology, Thiruvananthapuram, Kerala (India); James, Jija S.; Kesavadas, Chandrasekharan [SCTIMST, Department of Imaging Science and Interventional Radiology, Trivandrum, Kerala (India)

    2015-03-01

    Language lateralization is unique to humans. Functional MRI (fMRI) and diffusion tensor imaging (DTI) enable the study of language areas and white matter fibers involved in language, respectively. The objective of this study was to correlate arcuate fasciculus (AF) laterality by diffusion tensor imaging with that by fMRI in preadolescent children which has not yet been reported. Ten children between 8 and 12 years were subjected to fMRI and DTI imaging using Siemens 1.5 T MRI. Two language fMRI paradigms - visual verb generation and word pair task - were used. Analysis was done using SPM8 software. In DTI, the fiber volume of the arcuate fasciculus (AFV) and fractional anisotropy (FA) was measured. The fMRI Laterality Index (fMRI-LI) and DTI Laterality Index (DTI-LI) were calculated and their correlation assessed using the Pearson Correlation Index. Of ten children, mean age 10.6 years, eight showed left lateralization while bilateral language lateralization was seen in two. AFV by DTI was more on the left side in seven of the eight children who had left lateralization by fMRI. DTI could not trace the AF in one child. Of the two with bilateral language lateralization on fMRI, one showed larger AFV on the right side while the other did not show any asymmetry. There was a significant correlation (p < 0.02) between fMRI-LI and DTI-LI. Group mean of AFV by DTI was higher on the left side (2659.89 ± 654.75 mm{sup 3}) as compared to the right (1824.11 ± 582.81 mm{sup 3}) (p < 0.01). Like fMRI, DTI also reveals language laterality in children with a high degree of correlation between the two imaging modalities. (orig.)

  15. Correlation of human papillomavirus status with apparent diffusion coefficient of diffusion-weighted MRI in head and neck squamous cell carcinomas.

    Science.gov (United States)

    Driessen, Juliette P; van Bemmel, Alexander J M; van Kempen, Pauline M W; Janssen, Luuk M; Terhaard, Chris H J; Pameijer, Frank A; Willems, Stefan M; Stegeman, Inge; Grolman, Wilko; Philippens, Marielle E P

    2016-04-01

    Identification of prognostic patient characteristics in head and neck squamous cell carcinoma (HNSCC) is of great importance. Human papillomavirus (HPV)-positive HNSCCs have favorable response to (chemo)radiotherapy. Apparent diffusion coefficient, derived from diffusion-weighted MRI, has also shown to predict treatment response. The purpose of this study was to evaluate the correlation between HPV status and apparent diffusion coefficient. Seventy-three patients with histologically proven HNSCC were retrospectively analyzed. Mean pretreatment apparent diffusion coefficient was calculated by delineation of total tumor volume on diffusion-weighted MRI. HPV status was analyzed and correlated to apparent diffusion coefficient. Six HNSCCs were HPV-positive. HPV-positive HNSCC showed significantly lower apparent diffusion coefficient compared to HPV-negative. This correlation was independent of other patient characteristics. In HNSCC, positive HPV status correlates with low mean apparent diffusion coefficient. The favorable prognostic value of low pretreatment apparent diffusion coefficient might be partially attributed to patients with a positive HPV status. © 2015 Wiley Periodicals, Inc. Head Neck 38: E613-E618, 2016. © 2015 Wiley Periodicals, Inc.

  16. Quantitative diffusion characteristics of the human brain depend on MRI sequence parameters

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, M.; Blumhardt, L.D. [University of Nottingham, Department of Neurology, Royal Preston Hospital, Preston (United Kingdom); Morgan, P.S. [Division of Academic Radiology, Queens Medical Centre, Nottingham (United Kingdom)

    2002-07-01

    Quantitative diffusion-weighted MRI has been applied to the study of neurological diseases, including multiple sclerosis, where the molecular self-diffusion coefficient D has been measured in both lesions and normal-appearing white matter. Histograms of D have been used as a novel measure of the ''lesion load'', with potential applications that include the monitoring of efficacy in new treatment trials. However different ways of measuring D may affect its value, making comparison between different centres and research groups impossible. We aimed to assess the effect, if any, of using two different MRI sequences on the value of D. We studied 13 healthy volunteers, using two different quantitative diffusion sequences (including different b{sub max} values and gradient applications). Maps of D were analysed using both regions of interest (ROI) in white matter and ''whole brain'' histograms, and compared between the two sequences. In addition, we studied three standardised test liquids (with known values of D) using both sequences. Histograms from the two sequences had different distributions, with a greater spread and higher peak position from the sequence with lower b{sub max}. This greater spread of D was also evident in the white matter and test liquid ROI. ''Limits of agreement'' analysis demonstrated that the differences could be clinically relevant, despite significant correlations between the sequences obtained using simple rank methods. We conclude that different quantitative diffusion sequences are unlikely to produce directly comparable values of D, particularly if different b{sub max} values are used. In addition, the use of inappropriate statistical tests may give false impressions of close agreement. Standardisation of methods for the measurement of D are required if these techniques are to become useful tools, for example in monitoring changes in the disease burden of multiple sclerosis. (orig.)

  17. Quantitative diffusion characteristics of the human brain depend on MRI sequence parameters

    International Nuclear Information System (INIS)

    Wilson, M.; Blumhardt, L.D.; Morgan, P.S.

    2002-01-01

    Quantitative diffusion-weighted MRI has been applied to the study of neurological diseases, including multiple sclerosis, where the molecular self-diffusion coefficient D has been measured in both lesions and normal-appearing white matter. Histograms of D have been used as a novel measure of the ''lesion load'', with potential applications that include the monitoring of efficacy in new treatment trials. However different ways of measuring D may affect its value, making comparison between different centres and research groups impossible. We aimed to assess the effect, if any, of using two different MRI sequences on the value of D. We studied 13 healthy volunteers, using two different quantitative diffusion sequences (including different b max values and gradient applications). Maps of D were analysed using both regions of interest (ROI) in white matter and ''whole brain'' histograms, and compared between the two sequences. In addition, we studied three standardised test liquids (with known values of D) using both sequences. Histograms from the two sequences had different distributions, with a greater spread and higher peak position from the sequence with lower b max . This greater spread of D was also evident in the white matter and test liquid ROI. ''Limits of agreement'' analysis demonstrated that the differences could be clinically relevant, despite significant correlations between the sequences obtained using simple rank methods. We conclude that different quantitative diffusion sequences are unlikely to produce directly comparable values of D, particularly if different b max values are used. In addition, the use of inappropriate statistical tests may give false impressions of close agreement. Standardisation of methods for the measurement of D are required if these techniques are to become useful tools, for example in monitoring changes in the disease burden of multiple sclerosis. (orig.)

  18. SCT: Spinal Cord Toolbox, an open-source software for processing spinal cord MRI data.

    Science.gov (United States)

    De Leener, Benjamin; Lévy, Simon; Dupont, Sara M; Fonov, Vladimir S; Stikov, Nikola; Louis Collins, D; Callot, Virginie; Cohen-Adad, Julien

    2017-01-15

    For the past 25 years, the field of neuroimaging has witnessed the development of several software packages for processing multi-parametric magnetic resonance imaging (mpMRI) to study the brain. These software packages are now routinely used by researchers and clinicians, and have contributed to important breakthroughs for the understanding of brain anatomy and function. However, no software package exists to process mpMRI data of the spinal cord. Despite the numerous clinical needs for such advanced mpMRI protocols (multiple sclerosis, spinal cord injury, cervical spondylotic myelopathy, etc.), researchers have been developing specific tools that, while necessary, do not provide an integrative framework that is compatible with most usages and that is capable of reaching the community at large. This hinders cross-validation and the possibility to perform multi-center studies. In this study we introduce the Spinal Cord Toolbox (SCT), a comprehensive software dedicated to the processing of spinal cord MRI data. SCT builds on previously-validated methods and includes state-of-the-art MRI templates and atlases of the spinal cord, algorithms to segment and register new data to the templates, and motion correction methods for diffusion and functional time series. SCT is tailored towards standardization and automation of the processing pipeline, versatility, modularity, and it follows guidelines of software development and distribution. Preliminary applications of SCT cover a variety of studies, from cross-sectional area measures in large databases of patients, to the precise quantification of mpMRI metrics in specific spinal pathways. We anticipate that SCT will bring together the spinal cord neuroimaging community by establishing standard templates and analysis procedures. Copyright © 2016 Elsevier Inc. All rights reserved.

  19. Brain morphological and microstructural features in cryptogenic late-onset temporal lobe epilepsy: a structural and diffusion MRI study.

    Science.gov (United States)

    Sone, Daichi; Sato, Noriko; Kimura, Yukio; Watanabe, Yutaka; Okazaki, Mitsutoshi; Matsuda, Hiroshi

    2018-04-13

    Although epilepsy in the elderly has attracted attention recently, there are few systematic studies of neuroimaging in such patients. In this study, we used structural MRI and diffusion tensor imaging (DTI) to investigate the morphological and microstructural features of the brain in late-onset temporal lobe epilepsy (TLE). We recruited patients with TLE and an age of onset > 50 years (late-TLE group) and age- and sex-matched healthy volunteers (control group). 3-Tesla MRI scans, including 3D T1-weighted images and 15-direction DTI, showed normal findings on visual assessment in both groups. We used Statistical Parametric Mapping 12 (SPM12) for gray and white matter structural normalization and comparison and used Tract-Based Spatial Statistics (TBSS) for fractional anisotropy and mean diffusivity comparisons of DTI. In both methods, p < 0.05 (family-wise error) was considered statistically significant. In total, 30 patients with late-onset TLE (mean ± SD age, 66.8 ± 8.4; mean ± SD age of onset, 63.0 ± 7.6 years) and 40 healthy controls (mean ± SD age, 66.6 ± 8.5 years) were enrolled. The late-onset TLE group showed significant gray matter volume increases in the bilateral amygdala and anterior hippocampus and significantly reduced mean diffusivity in the left temporofrontal lobe, internal capsule, and brainstem. No significant changes were evident in white matter volume or fractional anisotropy. Our findings may reflect some characteristics or mechanisms of cryptogenic TLE in the elderly, such as inflammatory processes.

  20. Prospective comparison of T2w-MRI and dynamic-contrast-enhanced MRI, 3D-MR spectroscopic imaging or diffusion-weighted MRI in repeat TRUS-guided biopsies

    Energy Technology Data Exchange (ETDEWEB)

    Portalez, Daniel [Clinique Pasteur, 45, Department of Radiology, Toulouse (France); Rollin, Gautier; Mouly, Patrick; Jonca, Frederic; Malavaud, Bernard [Hopital de Rangueil, Department of Urology, Toulouse Cedex 9 (France); Leandri, Pierre [Clinique Saint Jean, 20, Department of Urology, Toulouse (France); Elman, Benjamin [Clinique Pasteur, 45, Department of Urology, Toulouse (France)

    2010-12-15

    To compare T2-weighted MRI and functional MRI techniques in guiding repeat prostate biopsies. Sixty-eight patients with a history of negative biopsies, negative digital rectal examination and elevated PSA were imaged before repeat biopsies. Dichotomous criteria were used with visual validation of T2-weighted MRI, dynamic contrast-enhanced MRI and literature-derived cut-offs for 3D-spectroscopy MRI (choline-creatine-to-citrate ratio >0.86) and diffusion-weighted imaging (ADC x 10{sup 3} mm{sup 2}/s < 1.24). For each segment and MRI technique, results were rendered as being suspicious/non-suspicious for malignancy. Sextant biopsies, transition zone biopsies and at least two additional biopsies of suspicious areas were taken. In the peripheral zones, 105/408 segments and in the transition zones 19/136 segments were suspicious according to at least one MRI technique. A total of 28/68 (41.2%) patients were found to have cancer. Diffusion-weighted imaging exhibited the highest positive predictive value (0.52) compared with T2-weighted MRI (0.29), dynamic contrast-enhanced MRI (0.33) and 3D-spectroscopy MRI (0.25). Logistic regression showed the probability of cancer in a segment increasing 12-fold when T2-weighted and diffusion-weighted imaging MRI were both suspicious (63.4%) compared with both being non-suspicious (5.2%). The proposed system of analysis and reporting could prove clinically relevant in the decision whether to repeat targeted biopsies. (orig.)

  1. Brain diffusion tensor MRI in systematic lupus erythematosus: A systematic review.

    Science.gov (United States)

    Costallat, Beatriz Lavras; Ferreira, Daniel Miranda; Lapa, Aline Tamires; Rittner, Letícia; Costallat, Lilian Tereza Lavras; Appenzeller, Simone

    2018-01-01

    Diffusion tensor imaging (DTI) maps the brain's microstructure by measuring fractional anisotropy (FA) and mean diffusivity (MD). This systematic review describes brain diffusion tensor Magnetic resonance imaging (MRI) studies in systemic lupus erythematosus (SLE).The literature was reviewed following the PRISMA guidelines and using the terms "lupus", "systemic lupus erythematosus", "SLE", "diffusion tensor imaging", "DTI", "white matter" (WM), "microstructural damage", "tractography", and "fractional anisotropy"; the search included articles published in English from January 2007 to April 2017. The subjects included in the study were selected according to the ACR criteria and included 195 SLE patients with neuropsychiatric manifestation (NPSLE), 299 without neuropsychiatric manifestation (non-NPSLE), and 423 healthy controls (HC). Most studies identified significantly reduced FA and increased MD values in several WM regions of both NPSLE and non-NPSLE patients compared to HC. Subclinical microstructural changes were observed in either regional areas or the entire brain in both the non-NPSLE and NPSLE groups. Copyright © 2017 Elsevier B.V. All rights reserved.

  2. Physical bases for diffusion welding processes optimization

    International Nuclear Information System (INIS)

    Bulygina, S.M.; Berber, N.N.; Mukhambetov, D.G.

    1999-01-01

    One of wide-spread method of different materials joint is diffusion welding. It has being brought off at the expense of mutual diffusion of atoms of contacting surfaces under long-duration curing at its heating and compression. Welding regime in dependence from properties of welding details is defining of three parameters: temperature, pressure, time. Problem of diffusion welding optimization concludes in determination less values of these parameters, complying with requirements for quality of welded joint. In the work experiments on diffusion welding for calculated temperature and for given surface's roughness were carried out. Tests conduct on samples of iron and iron-nickel alloy with size 1·1·1 cm 3 . Optimal regime of diffusion welding of examined samples in vacuum is defined. It includes compression of welding samples, heating, isothermal holding at temperature 650 deg C during 0.5 h and affords the required homogeneity of joint

  3. Heroin-induced leukoencephalopathy: characterization using MRI, diffusion-weighted imaging, and MR spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Offiah, C. [Department of Neuroradiology, St Bartholomew' s and the London Hospitals NHS Trust, London (United Kingdom); Hall, E. [Department of Neuroradiology, St Bartholomew' s and the London Hospitals NHS Trust, London (United Kingdom)], E-mail: curtis.offiah@bartsandthelondon.nhs.uk

    2008-02-15

    Aim: To describe the magnetic resonance imaging (MRI) characteristics of heroin-induced leukoencephalopathy or 'chasing the dragon syndrome' and, in particular, the diffusion-weighted imaging (DWI) and MR spectroscopy (MRS) features. Material and methods: Six patients with a clinical or histopathological diagnosis of heroin-induced leukoencephalopathy were identified and MRI examinations, including DWI and single-voxel MRS, reviewed. Results: Cerebellar white matter was involved in all six cases demonstrating similar symmetrical distribution with sparing of the dentate nuclei. Brain stem signal change was evident in five of the six patients imaged. Supratentorial brain parenchymal involvement, as well as brain stem involvement, correlated anatomically with corticospinal tract distribution. None of the areas of signal abnormality were restricted on DWI. Of those patients subjected to MRS, the areas of parenchymal damage demonstrated reduced N-acetylaspartate, reduced choline, and elevated lactate. Conclusion: Heroin-induced leukoencephalopathy results in characteristic and highly specific signal abnormalities on MRI, which can greatly aid diagnosis. DWI and MRS findings can be explained by known reported neuropathological descriptions in this condition and can be used to support a proposed mechanism for the benefit of current recommended drug treatment regimes.

  4. Postmortem diffusion MRI of the entire human spinal cord at microscopic resolution

    Directory of Open Access Journals (Sweden)

    Evan Calabrese

    Full Text Available The human spinal cord is a central nervous system structure that plays an important role in normal motor and sensory function, and can be affected by many debilitating neurologic diseases. Due to its clinical importance, the spinal cord is frequently the subject of imaging research. Common methods for visualizing spinal cord anatomy and pathology include histology and magnetic resonance imaging (MRI, both of which have unique benefits and drawbacks. Postmortem microscopic resolution MRI of fixed specimens, sometimes referred to as magnetic resonance microscopy (MRM, combines many of the benefits inherent to both techniques. However, the elongated shape of the human spinal cord, along with hardware and scan time limitations, have restricted previous microscopic resolution MRI studies (both in vivo and ex vivo to small sections of the cord. Here we present the first MRM dataset of the entire postmortem human spinal cord. These data include 50 μm isotropic resolution anatomic image data and 100 μm isotropic resolution diffusion data, made possible by a 280 h long multi-segment acquisition and automated image segment composition. We demonstrate the use of these data for spinal cord lesion detection, automated volumetric gray matter segmentation, and quantitative spinal cord morphometry including estimates of cross sectional dimensions and gray matter fraction throughout the length of the cord. Keywords: Spinal cord, Magnetic resonance microscopy, Tractography, Human, Gray matter

  5. Can musical training influence brain connectivity? Evidence from diffusion tensor MRI.

    Science.gov (United States)

    Moore, Emma; Schaefer, Rebecca S; Bastin, Mark E; Roberts, Neil; Overy, Katie

    2014-06-10

    In recent years, musicians have been increasingly recruited to investigate grey and white matter neuroplasticity induced by skill acquisition. The development of Diffusion Tensor Magnetic Resonance Imaging (DT-MRI) has allowed more detailed investigation of white matter connections within the brain, addressing questions about the effect of musical training on connectivity between specific brain regions. Here, current DT-MRI analysis techniques are discussed and the available evidence from DT-MRI studies into differences in white matter architecture between musicians and non-musicians is reviewed. Collectively, the existing literature tends to support the hypothesis that musical training can induce changes in cross-hemispheric connections, with significant differences frequently reported in various regions of the corpus callosum of musicians compared with non-musicians. However, differences found in intra-hemispheric fibres have not always been replicated, while findings regarding the internal capsule and corticospinal tracts appear to be contradictory. There is also recent evidence to suggest that variances in white matter structure in non-musicians may correlate with their ability to learn musical skills, offering an alternative explanation for the structural differences observed between musicians and non-musicians. Considering the inconsistencies in the current literature, possible reasons for conflicting results are offered, along with suggestions for future research in this area.

  6. Diffuse intrinsic pontine glioma: is MRI surveillance improved by region of interest volumetry?

    Science.gov (United States)

    Riley, Garan T; Armitage, Paul A; Batty, Ruth; Griffiths, Paul D; Lee, Vicki; McMullan, John; Connolly, Daniel J A

    2015-02-01

    Paediatric diffuse intrinsic pontine glioma (DIPG) is noteworthy for its fibrillary infiltration through neuroparenchyma and its resultant irregular shape. Conventional volumetry methods aim to approximate such irregular tumours to a regular ellipse, which could be less accurate when assessing treatment response on surveillance MRI. Region-of-interest (ROI) volumetry methods, using manually traced tumour profiles on contiguous imaging slices and subsequent computer-aided calculations, may prove more reliable. To evaluate whether the reliability of MRI surveillance of DIPGs can be improved by the use of ROI-based volumetry. We investigated the use of ROI- and ellipsoid-based methods of volumetry for paediatric DIPGs in a retrospective review of 22 MRI examinations. We assessed the inter- and intraobserver variability of the two methods when performed by four observers. ROI- and ellipsoid-based methods strongly correlated for all four observers. The ROI-based volumes showed slightly better agreement both between and within observers than the ellipsoid-based volumes (inter-[intra-]observer agreement 89.8% [92.3%] and 83.1% [88.2%], respectively). Bland-Altman plots show tighter limits of agreement for the ROI-based method. Both methods are reproducible and transferrable among observers. ROI-based volumetry appears to perform better with greater intra- and interobserver agreement for complex-shaped DIPG.

  7. Diffuse intrinsic pontine glioma: is MRI surveillance improved by region of interest volumetry?

    International Nuclear Information System (INIS)

    Riley, Garan T.; Armitage, Paul A.; Griffiths, Paul D.; Batty, Ruth; Connolly, Daniel J.A.; Lee, Vicki; McMullan, John

    2015-01-01

    Paediatric diffuse intrinsic pontine glioma (DIPG) is noteworthy for its fibrillary infiltration through neuroparenchyma and its resultant irregular shape. Conventional volumetry methods aim to approximate such irregular tumours to a regular ellipse, which could be less accurate when assessing treatment response on surveillance MRI. Region-of-interest (ROI) volumetry methods, using manually traced tumour profiles on contiguous imaging slices and subsequent computer-aided calculations, may prove more reliable. To evaluate whether the reliability of MRI surveillance of DIPGs can be improved by the use of ROI-based volumetry. We investigated the use of ROI- and ellipsoid-based methods of volumetry for paediatric DIPGs in a retrospective review of 22 MRI examinations. We assessed the inter- and intraobserver variability of the two methods when performed by four observers. ROI- and ellipsoid-based methods strongly correlated for all four observers. The ROI-based volumes showed slightly better agreement both between and within observers than the ellipsoid-based volumes (inter-[intra-]observer agreement 89.8% [92.3%] and 83.1% [88.2%], respectively). Bland-Altman plots show tighter limits of agreement for the ROI-based method. Both methods are reproducible and transferrable among observers. ROI-based volumetry appears to perform better with greater intra- and interobserver agreement for complex-shaped DIPG. (orig.)

  8. Diffuse intrinsic pontine glioma: is MRI surveillance improved by region of interest volumetry?

    Energy Technology Data Exchange (ETDEWEB)

    Riley, Garan T. [University Hospital of North Tees, Department of General Radiology, North Tees and Hartlepool NHS Foundation Trust, Stockton-on-Tees, Cleveland (United Kingdom); Armitage, Paul A.; Griffiths, Paul D. [University of Sheffield, Academic Unit of Radiology, Sheffield (United Kingdom); Batty, Ruth; Connolly, Daniel J.A. [Sheffield Children' s NHS Foundation Trust, Department of Radiology, Sheffield (United Kingdom); Lee, Vicki [Sheffield Children' s NHS Foundation Trust, Department of Oncology, Sheffield (United Kingdom); McMullan, John [Sheffield Children' s NHS Foundation Trust, Department of Neurosurgery, Sheffield (United Kingdom)

    2014-08-21

    Paediatric diffuse intrinsic pontine glioma (DIPG) is noteworthy for its fibrillary infiltration through neuroparenchyma and its resultant irregular shape. Conventional volumetry methods aim to approximate such irregular tumours to a regular ellipse, which could be less accurate when assessing treatment response on surveillance MRI. Region-of-interest (ROI) volumetry methods, using manually traced tumour profiles on contiguous imaging slices and subsequent computer-aided calculations, may prove more reliable. To evaluate whether the reliability of MRI surveillance of DIPGs can be improved by the use of ROI-based volumetry. We investigated the use of ROI- and ellipsoid-based methods of volumetry for paediatric DIPGs in a retrospective review of 22 MRI examinations. We assessed the inter- and intraobserver variability of the two methods when performed by four observers. ROI- and ellipsoid-based methods strongly correlated for all four observers. The ROI-based volumes showed slightly better agreement both between and within observers than the ellipsoid-based volumes (inter-[intra-]observer agreement 89.8% [92.3%] and 83.1% [88.2%], respectively). Bland-Altman plots show tighter limits of agreement for the ROI-based method. Both methods are reproducible and transferrable among observers. ROI-based volumetry appears to perform better with greater intra- and interobserver agreement for complex-shaped DIPG. (orig.)

  9. Postmortem diffusion MRI of the human brainstem and thalamus for deep brain stimulator electrode localization

    Science.gov (United States)

    Calabrese, Evan; Hickey, Patrick; Hulette, Christine; Zhang, Jingxian; Parente, Beth; Lad, Shivanand P.; Johnson, G. Allan

    2015-01-01

    Deep brain stimulation (DBS) is an established surgical therapy for medically refractory tremor disorders including essential tremor (ET) and is currently under investigation for use in a variety of other neurologic and psychiatric disorders. There is growing evidence that the anti-tremor effects of DBS for ET are directly related to modulation of the dentatorubrothalamic tract (DRT), a white matter pathway that connects the cerebellum, red nucleus, and ventral intermediate nucleus of the thalamus. Emerging white matter targets for DBS, like the DRT, will require improved 3D reference maps of deep brain anatomy and structural connectivity for accurate electrode targeting. High-resolution diffusion MRI of postmortem brain specimens can provide detailed volumetric images of important deep brain nuclei and 3D reconstructions of white matter pathways with probabilistic tractography techniques. We present a high spatial and angular resolution diffusion MRI template of the postmortem human brainstem and thalamus with 3D reconstructions of the nuclei and white matter tracts involved in ET circuitry. We demonstrate accurate registration of these data to in vivo, clinical images from patients receiving DBS therapy, and correlate electrode proximity to tractography of the DRT with improvement of ET symptoms. PMID:26043869

  10. Brain MRI diffusion-weighted imaging in patients with classical phenylketonuria

    Energy Technology Data Exchange (ETDEWEB)

    Manara, Renzo; Citton, Valentina; Carollo, Carla [University Hospital of Padua, Neuroradiologic Unit, Padua (Italy); Burlina, Alessandro P.; Ermani, Mario [University Hospital of Padua, Neurological Clinic, Department of Neuroscience, Padua (Italy); Vespignani, Francesco; Burlina, Alberto B. [University Hospital of Padua, Metabolic Diseases Unit, Department of Paediatrics, Padua (Italy)

    2009-12-15

    The aim of this study was to grade magnetic resonance white matter abnormalities (WMAs) of classical phenylketonuria (cPKU) patients treated from birth and to compare sensitivity and specificity of T2-weighted and diffusion-weighted images (DWI). Twenty early-treated cPKU patients still on a low-phenylalanine diet (12 males; mean age 21.2 years) and 26 normal subjects (ten males; mean age 25.1 years) were enrolled. Typical T2- and diffusion-weighted WMAs were semiquantitatively graded according to Thompson score (TS). Besides, a regional magnetic resonance imaging (MRI) score (mTS) was developed according to extension and intensity of WMAs. Phenylalanine and tyrosine plasma concentrations before performing MRI and the amino acid mean levels collected the year before MRI (Tyr{sub year} and Phe{sub year}) were measured. No patient with Phe{sub year} concentration below 460 {mu}mol/L showed WMAs. In cPKU patients, TS and mTS were significantly higher on DWI than on T2 images (3.50 vs 2.65 and 23.65 vs 15.85, respectively, p<0.002, Wilcoxon test). All controls were scored 0 on DWI, while in T2 images, TS and mTS were 0.19 and 1.70. DWI evaluated by mTS disclosed a frontotemporal, occipital, and parietal WM progressive involvement. TS and mTS, both on T2 images and on DWI, showed no correlation with tyrosine while they proved to have a strong correlation with phenylalaninemia and an excellent one with Phe{sub year} levels. Among the different MR sequences, DWI seems to be the most sensitive and reliable in detecting and grading the typical WMAs of cPKU patients. (orig.)

  11. Diffusion-weighted MRI of malignant versus benign portal vein thrombosis

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Jhii Hyun; Yu, Jeong Sik; Cho, Eun Suk; Chung, Jae Joon; Kim, Joo Hee; Kim, Ki Whang [Yonsei University College of Medicine, Gangnam Severance Hospital, Seoul(Korea, Republic of)

    2016-07-15

    To validate the diffusion-weighted MRI (DWI) for differentiation of benign from malignant portal vein thrombosis. The Institutional Review Board approved this retrospective study and waived informed consent. A total of 59 consecutive patients (52 men and 7 women, aged 40-85 years) with grossly defined portal vein thrombus (PVT) on hepatic MRI were retrospectively analyzed. Among them, liver cirrhosis was found in 45 patients, and hepatocellular carcinoma in 47 patients. DWI was performed using b values of 50 and 800 sec/mm2 at 1.5-T unit. A thrombus was considered malignant if it enhanced on dynamic CT or MRI; otherwise, it was considered bland. There were 18 bland thrombi and 49 malignant thrombi in 59 patients, including 8 patients with simultaneous benign and malignant PVT. Mean apparent diffusion coefficients (ADCs) of benign and malignant PVTs were compared by using Mann-Whitney U test. Diagnostic accuracy was evaluated using receiver operating characteristic (ROC) curve analysis. The mean ADC ± standard deviation of bland and malignant PVT were 1.00 ± 0.39 × 10(-3) mm{sup 2}/sec and 0.92 ± 0.25 × 10(-3) mm{sup 2}/sec, respectively; without significant difference (p = 0.799). The area under ROC curve for ADC was 0.520. An ADC value of > 1.35 × 10(-3) mm{sup 2}/sec predicted bland PVT with a specificity of 94.6% (95% confidence interval [CI]: 84.9-98.9%) and a sensitivity of 22.2% (95% CI: 6.4-47.6%), respectively. Due to the wide range and considerable overlap of the ADCs, DWI cannot differentiate the benign from malignant thrombi efficiently.

  12. Diffusion-weighted MRI of malignant versus benign portal vein thrombosis

    International Nuclear Information System (INIS)

    Ahn, Jhii Hyun; Yu, Jeong Sik; Cho, Eun Suk; Chung, Jae Joon; Kim, Joo Hee; Kim, Ki Whang

    2016-01-01

    To validate the diffusion-weighted MRI (DWI) for differentiation of benign from malignant portal vein thrombosis. The Institutional Review Board approved this retrospective study and waived informed consent. A total of 59 consecutive patients (52 men and 7 women, aged 40-85 years) with grossly defined portal vein thrombus (PVT) on hepatic MRI were retrospectively analyzed. Among them, liver cirrhosis was found in 45 patients, and hepatocellular carcinoma in 47 patients. DWI was performed using b values of 50 and 800 sec/mm2 at 1.5-T unit. A thrombus was considered malignant if it enhanced on dynamic CT or MRI; otherwise, it was considered bland. There were 18 bland thrombi and 49 malignant thrombi in 59 patients, including 8 patients with simultaneous benign and malignant PVT. Mean apparent diffusion coefficients (ADCs) of benign and malignant PVTs were compared by using Mann-Whitney U test. Diagnostic accuracy was evaluated using receiver operating characteristic (ROC) curve analysis. The mean ADC ± standard deviation of bland and malignant PVT were 1.00 ± 0.39 × 10(-3) mm 2 /sec and 0.92 ± 0.25 × 10(-3) mm 2 /sec, respectively; without significant difference (p = 0.799). The area under ROC curve for ADC was 0.520. An ADC value of > 1.35 × 10(-3) mm 2 /sec predicted bland PVT with a specificity of 94.6% (95% confidence interval [CI]: 84.9-98.9%) and a sensitivity of 22.2% (95% CI: 6.4-47.6%), respectively. Due to the wide range and considerable overlap of the ADCs, DWI cannot differentiate the benign from malignant thrombi efficiently

  13. Diffusion-Weighted MRI of Malignant versus Benign Portal Vein Thrombosis

    Energy Technology Data Exchange (ETDEWEB)

    Ahn, Jhii-Hyun; Yu, Jeong-Sik; Cho, Eun-Suk; Chung, Jae-Joon; Kim, Joo Hee; Kim, Ki Whang [Department of Radiology, Yonsei University College of Medicine, Gangnam Severance Hospital, Seoul 06273 (Korea, Republic of)

    2016-11-01

    To validate the diffusion-weighted MRI (DWI) for differentiation of benign from malignant portal vein thrombosis. The Institutional Review Board approved this retrospective study and waived informed consent. A total of 59 consecutive patients (52 men and 7 women, aged 40–85 years) with grossly defined portal vein thrombus (PVT) on hepatic MRI were retrospectively analyzed. Among them, liver cirrhosis was found in 45 patients, and hepatocellular carcinoma in 47 patients. DWI was performed using b values of 50 and 800 sec/mm{sup 2} at 1.5-T unit. A thrombus was considered malignant if it enhanced on dynamic CT or MRI; otherwise, it was considered bland. There were 18 bland thrombi and 49 malignant thrombi in 59 patients, including 8 patients with simultaneous benign and malignant PVT. Mean apparent diffusion coefficients (ADCs) of benign and malignant PVTs were compared by using Mann-Whitney U test. Diagnostic accuracy was evaluated using receiver operating characteristic (ROC) curve analysis. The mean ADC ± standard deviation of bland and malignant PVT were 1.00 ± 0.39 × 10{sup -3} mm{sup 2}/sec and 0.92 ± 0.25 × 10{sup -3} mm{sup 2}/sec, respectively; without significant difference (p = 0.799). The area under ROC curve for ADC was 0.520. An ADC value of > 1.35 × 10{sup -3} mm{sup 2}/sec predicted bland PVT with a specificity of 94.6% (95% confidence interval [CI]: 84.9–98.9%) and a sensitivity of 22.2% (95% CI: 6.4–47.6%), respectively. Due to the wide range and considerable overlap of the ADCs, DWI cannot differentiate the benign from malignant thrombi efficiently.

  14. Can MRI diffusion-weighted imaging identify postoperative residual/recurrent soft-tissue sarcomas?

    Directory of Open Access Journals (Sweden)

    Mai Maher ElDaly

    2018-01-01

    Full Text Available Purpose: The aim of this study was to evaluate contrast-enhanced magnetic resonance imaging (CE-MRI and quantitative diffusion-weighted imaging (DWI with apparent diffusion coefficient (ADC mapping in the detection of recurrent/residual postoperative soft tissue sarcomas. Materials and Methods: This study included 36 patients; 27 patients had postoperative recurrent/residual soft tissue sarcomas and 9 patients had postoperative and treatment-related changes (inflammation/fibrosis. The DWI was obtained with 3 b values including 0, 400, and 800 s/mm2. Calculation of the ADC value of the lesion was done via placing the region of interest (ROI to include the largest area of the lesion. ADC values were compared to histopathology. Results: Our results showed that including CE-MRI improved the diagnostic accuracy and sensitivity in recurrence detection compared to conventional non-enhanced sequences. However, it showed low specificity (55.56% with a high false-positive rate that may lead to an unnecessary biopsy of a mass such as region of postoperative scar tissue. Conclusion: The joint use of gadolinium-enhanced MRI and quantitative DWI with ADC mapping offer added value in the detection of recurrent/residual postoperative soft tissue sarcoma. This combined use increased both the diagnostic sensitivity and specificity with a cut-off average ADC value for detecting nonmyxoid recurrent/residual lesions ≤1.3 × 10−3 mm2/s (100% specificity and 90.48% sensitivity. Our results showed limited value of DWI with ADC mapping in assessing myxoid sarcomatous tumor recurrences.

  15. Diffusion-Weighted MRI of Malignant versus Benign Portal Vein Thrombosis

    International Nuclear Information System (INIS)

    Ahn, Jhii-Hyun; Yu, Jeong-Sik; Cho, Eun-Suk; Chung, Jae-Joon; Kim, Joo Hee; Kim, Ki Whang

    2016-01-01

    To validate the diffusion-weighted MRI (DWI) for differentiation of benign from malignant portal vein thrombosis. The Institutional Review Board approved this retrospective study and waived informed consent. A total of 59 consecutive patients (52 men and 7 women, aged 40–85 years) with grossly defined portal vein thrombus (PVT) on hepatic MRI were retrospectively analyzed. Among them, liver cirrhosis was found in 45 patients, and hepatocellular carcinoma in 47 patients. DWI was performed using b values of 50 and 800 sec/mm 2 at 1.5-T unit. A thrombus was considered malignant if it enhanced on dynamic CT or MRI; otherwise, it was considered bland. There were 18 bland thrombi and 49 malignant thrombi in 59 patients, including 8 patients with simultaneous benign and malignant PVT. Mean apparent diffusion coefficients (ADCs) of benign and malignant PVTs were compared by using Mann-Whitney U test. Diagnostic accuracy was evaluated using receiver operating characteristic (ROC) curve analysis. The mean ADC ± standard deviation of bland and malignant PVT were 1.00 ± 0.39 × 10 -3 mm 2 /sec and 0.92 ± 0.25 × 10 -3 mm 2 /sec, respectively; without significant difference (p = 0.799). The area under ROC curve for ADC was 0.520. An ADC value of > 1.35 × 10 -3 mm 2 /sec predicted bland PVT with a specificity of 94.6% (95% confidence interval [CI]: 84.9–98.9%) and a sensitivity of 22.2% (95% CI: 6.4–47.6%), respectively. Due to the wide range and considerable overlap of the ADCs, DWI cannot differentiate the benign from malignant thrombi efficiently

  16. Brain changes following four weeks of unimanual motor training: Evidence from fMRI-guided diffusion MRI tractography.

    Science.gov (United States)

    Reid, Lee B; Sale, Martin V; Cunnington, Ross; Mattingley, Jason B; Rose, Stephen E

    2017-09-01

    We have reported reliable changes in behavior, brain structure, and function in 24 healthy right-handed adults who practiced a finger-thumb opposition sequence task with their left hand for 10 min daily, over 4 weeks. Here, we extend these findings by using diffusion MRI to investigate white-matter changes in the corticospinal tract, basal-ganglia, and connections of the dorsolateral prefrontal cortex. Twenty-three participant datasets were available with pre-training and post-training scans. Task performance improved in all participants (mean: 52.8%, SD: 20.0%; group P right caudate nucleus (4.9%; P left nucleus accumbens (-1.3%; P right corticospinal tract (mean 3.28%; P left corticospinal tract did not show any changes. FA also increased in white matter connections between the right middle frontal gyrus and both right caudate nucleus (17/22 participants; P right supplementary motor area (18/22 participants; P left (non-trained) hemisphere. In combination with our functional and structural findings, this study provides detailed, multifocal evidence for widespread neuroplastic changes in the human brain resulting from motor training. Hum Brain Mapp 38:4302-4312, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  17. Automatic segmentation of human cortical layer-complexes and architectural areas using diffusion MRI and its validation

    Directory of Open Access Journals (Sweden)

    Matteo Bastiani

    2016-11-01

    Full Text Available Recently, several magnetic resonance imaging contrast mechanisms have been shown to distinguish cortical substructure corresponding to selected cortical layers. Here, we investigate cortical layer and area differentiation by automatized unsupervised clustering of high resolution diffusion MRI data. Several groups of adjacent layers could be distinguished in human primary motor and premotor cortex. We then used the signature of diffusion MRI signals along cortical depth as a criterion to detect area boundaries and find borders at which the signature changes abruptly. We validate our clustering results by histological analysis of the same tissue. These results confirm earlier studies which show that diffusion MRI can probe layer-specific intracortical fiber organization and, moreover, suggests that it contains enough information to automatically classify architecturally distinct cortical areas. We discuss the strengths and weaknesses of the automatic clustering approach and its appeal for MR-based cortical histology.

  18. Auditory intensity processing: Effect of MRI background noise.

    Science.gov (United States)

    Angenstein, Nicole; Stadler, Jörg; Brechmann, André

    2016-03-01

    Studies on active auditory intensity discrimination in humans showed equivocal results regarding the lateralization of processing. Whereas experiments with a moderate background found evidence for right lateralized processing of intensity, functional magnetic resonance imaging (fMRI) studies with background scanner noise suggest more left lateralized processing. With the present fMRI study, we compared the task dependent lateralization of intensity processing between a conventional continuous echo planar imaging (EPI) sequence with a loud background scanner noise and a fast low-angle shot (FLASH) sequence with a soft background scanner noise. To determine the lateralization of the processing, we employed the contralateral noise procedure. Linearly frequency modulated (FM) tones were presented monaurally with and without contralateral noise. During both the EPI and the FLASH measurement, the left auditory cortex was more strongly involved than the right auditory cortex while participants categorized the intensity of FM tones. This was shown by a strong effect of the additional contralateral noise on the activity in the left auditory cortex. This means a massive reduction in background scanner noise still leads to a significant left lateralized effect. This suggests that the reversed lateralization in fMRI studies with loud background noise in contrast to studies with softer background cannot be fully explained by the MRI background noise. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Diffusion-weighted imaging findings on MRI as the sole radiographic findings in a child with proven herpes simplex encephalitis

    Energy Technology Data Exchange (ETDEWEB)

    Obeid, Makram; Franklin, Jeremy; Shrestha, Shraddha; Johnson, Lara; Hurst, Daniel [Texas Tech University Health Sciences Center, Department of Pediatrics, Lubbock, TX (United States); Quattromani, Frank [Texas Tech University Health Sciences Center, Department of Radiology, Lubbock, TX (United States)

    2007-11-15

    We present a case of herpes simplex encephalitis in an 8-year-old girl, in whom hyperintensity was detected on diffusion-weighted imaging (DWI) while conventional MRI sequences were normal 1 week after the onset of neurological symptoms. This case is rare in that a child beyond the neonatal period with focal herpes simplex encephalitis had an abnormal DWI sequence as the only MRI finding. (orig.)

  20. Edgeworth expansion for functionals of continuous diffusion processes

    DEFF Research Database (Denmark)

    Podolskij, Mark; Yoshida, Nakahiro

    This paper presents new results on the Edgeworth expansion for high frequency functionals of continuous diffusion processes. We derive asymptotic expansions for weighted functionals of the Brownian motion and apply them to provide the Edgeworth expansion for power variation of diffusion processes....... Our methodology relies on martingale embedding, Malliavin calculus and stable central limit theorems for semimartingales. Finally, we demonstrate the density expansion for studentized statistics of power variations.......This paper presents new results on the Edgeworth expansion for high frequency functionals of continuous diffusion processes. We derive asymptotic expansions for weighted functionals of the Brownian motion and apply them to provide the Edgeworth expansion for power variation of diffusion processes...

  1. Application of probabilistically weighted graphs to image-based diagnosis of Alzheimer's disease using diffusion MRI

    Science.gov (United States)

    Maryam, Syeda; McCrackin, Laura; Crowley, Mark; Rathi, Yogesh; Michailovich, Oleg

    2017-03-01

    The world's aging population has given rise to an increasing awareness towards neurodegenerative disorders, including Alzheimers Disease (AD). Treatment options for AD are currently limited, but it is believed that future success depends on our ability to detect the onset of the disease in its early stages. The most frequently used tools for this include neuropsychological assessments, along with genetic, proteomic, and image-based diagnosis. Recently, the applicability of Diffusion Magnetic Resonance Imaging (dMRI) analysis for early diagnosis of AD has also been reported. The sensitivity of dMRI to the microstructural organization of cerebral tissue makes it particularly well-suited to detecting changes which are known to occur in the early stages of AD. Existing dMRI approaches can be divided into two broad categories: region-based and tract-based. In this work, we propose a new approach, which extends region-based approaches to the simultaneous characterization of multiple brain regions. Given a predefined set of features derived from dMRI data, we compute the probabilistic distances between different brain regions and treat the resulting connectivity pattern as an undirected, fully-connected graph. The characteristics of this graph are then used as markers to discriminate between AD subjects and normal controls (NC). Although in this preliminary work we omit subjects in the prodromal stage of AD, mild cognitive impairment (MCI), our method demonstrates perfect separability between AD and NC subject groups with substantial margin, and thus holds promise for fine-grained stratification of NC, MCI and AD populations.

  2. TU-AB-BRA-07: Distortion-Free 3D Diffusion MRI On An MRI-Guided Radiotherapy System for Longitudinal Tumor Response Assessment

    International Nuclear Information System (INIS)

    Gao, Y; Yang, Y; Rangwala, N; Cao, M; Low, D; Hu, P

    2016-01-01

    Purpose: To develop a reliable, 3D distortion-free diffusion MRI technique for longitudinal tumor response assessment and MRI-guided adaptive radiotherapy(RT). Methods: A diffusion prepared 3D turbo spin echo readout (DP-TSE) sequence was developed and compared with the conventional diffusion-weighted single-shot echo-planar-imaging (DW-ssEPI) sequence in a commercially available diffusion phantom, and one head-and-neck and one brain cancer patient on an MRI-guided RT system (ViewRay). In phantom study, the geometric fidelity was quantified as the ratio between the left-right (RL) and anterior-posterior (AP) dimension. Ten slices were measured on DP-TSE, DW-ssEPI and standard TSE images where the later was used as the geometric reference. ADC accuracy was verified at both 0°C (reference ADC available) and room temperature with a range of diffusivity between 0.35 and 2.0*10"−"3mm"2/s. The ADC reproducibility was assessed based on 8 room-temperature measurements on 6 different days. In the pilot single-slice in-vivo study, CT images were used as the geometric reference, and ADC maps from both diffusion sequences were compared. Results: Distortion and susceptive-related artifact were severe in DW-ssEPI, with significantly lower RL/AP ratio (0.9579±0.0163) than DP-TSE (0.9990±0.0031) and TSE (0.9995±0.0031). ADCs from the two diffusion sequences both matched well with the vendor-provided values at 0°C; however DW-ssEPI fails to provide accurate ADC for high diffusivity vials at room temperature due to high noise level (10 times higher than DP-TSE). The DP-TSE sequence had excellent ADC reproducibility with <4% ADC variation among 8 separate measurements. In patient study, DP-TSE exhibited substantially improved geometric reliability. ROI analysis in ADC maps generated from DP-TSE and DW-ssEPI showed <5% difference where high b-value images were excluded from the latter approach due to excessive noise level. Conclusion: A diffusion MRI sequence with excellent

  3. TU-AB-BRA-07: Distortion-Free 3D Diffusion MRI On An MRI-Guided Radiotherapy System for Longitudinal Tumor Response Assessment

    Energy Technology Data Exchange (ETDEWEB)

    Gao, Y; Yang, Y; Rangwala, N; Cao, M; Low, D; Hu, P [UCLA School of Medicine, Los Angeles, CA (United States)

    2016-06-15

    Purpose: To develop a reliable, 3D distortion-free diffusion MRI technique for longitudinal tumor response assessment and MRI-guided adaptive radiotherapy(RT). Methods: A diffusion prepared 3D turbo spin echo readout (DP-TSE) sequence was developed and compared with the conventional diffusion-weighted single-shot echo-planar-imaging (DW-ssEPI) sequence in a commercially available diffusion phantom, and one head-and-neck and one brain cancer patient on an MRI-guided RT system (ViewRay). In phantom study, the geometric fidelity was quantified as the ratio between the left-right (RL) and anterior-posterior (AP) dimension. Ten slices were measured on DP-TSE, DW-ssEPI and standard TSE images where the later was used as the geometric reference. ADC accuracy was verified at both 0°C (reference ADC available) and room temperature with a range of diffusivity between 0.35 and 2.0*10{sup −3}mm{sup 2}/s. The ADC reproducibility was assessed based on 8 room-temperature measurements on 6 different days. In the pilot single-slice in-vivo study, CT images were used as the geometric reference, and ADC maps from both diffusion sequences were compared. Results: Distortion and susceptive-related artifact were severe in DW-ssEPI, with significantly lower RL/AP ratio (0.9579±0.0163) than DP-TSE (0.9990±0.0031) and TSE (0.9995±0.0031). ADCs from the two diffusion sequences both matched well with the vendor-provided values at 0°C; however DW-ssEPI fails to provide accurate ADC for high diffusivity vials at room temperature due to high noise level (10 times higher than DP-TSE). The DP-TSE sequence had excellent ADC reproducibility with <4% ADC variation among 8 separate measurements. In patient study, DP-TSE exhibited substantially improved geometric reliability. ROI analysis in ADC maps generated from DP-TSE and DW-ssEPI showed <5% difference where high b-value images were excluded from the latter approach due to excessive noise level. Conclusion: A diffusion MRI sequence with

  4. Assessment of renal fibrosis in chronic kidney disease using diffusion-weighted MRI

    International Nuclear Information System (INIS)

    Zhao, J.; Wang, Z.J.; Liu, M.; Zhu, J.; Zhang, X.; Zhang, T.; Li, S.; Li, Y.

    2014-01-01

    Aim: To assess the performance of diffusion-weighted magnetic resonance imaging (MRI) for the assessment of renal fibrosis in chronic kidney disease (CKD), with histopathology as a reference standard. Materials and methods: Forty patients with CKD and 30 healthy volunteers were recruited for the study. All participants underwent diffusion-weighted MRI. Renal biopsy was performed in 25 patients with CKD. Mean renal medullary and cortical apparent diffusion coefficient (ADC) values were compared between CKD patients and the healthy volunteers. Pearson's correlation coefficient was calculated to investigate the relationship between ADC values, serum creatinine (SCr), estimated glomerular filtration rate (eGFR), 24 h urinary protein (24h-UPRO), and renal histopathological scores. Results: Cortical and medullary ADC values in the CKD group were significantly lower compared to those in the healthy controls. In the CKD group, a significant negative correlation was found between cortical ADC values and SCr/24h-UPRO, and significant positive correlation was found between cortical ADC and eGFR. There was also a significant negative correlation between medullary ADC values and SCr. Both cortical and medullary ADC values were significantly correlated with histopathological fibrosis score. Conclusion: Renal ADC values strongly correlate with histological measures of fibrosis, and have the potential to enhance the non-invasive monitoring of chronic kidney disease. - Highlights: • Renal ADC values in the CKD patients were lower than those in controls. • Renal ADC values were strongly correlated with histological fibrosis score. • Renal ADC values have the potential to enhance the noninvasive monitoring of CKD

  5. Transition Process from Diffuser Stall to Stage Stall in a Centrifugal Compressor with a Vaned Diffuser

    Directory of Open Access Journals (Sweden)

    Nobumichi Fujisawa

    2017-01-01

    Full Text Available The transition process from a diffuser rotating stall to a stage stall in a centrifugal compressor with a vaned diffuser was investigated by experimental and numerical analyses. From the velocity measurements, it was found that the rotating stall existed on the shroud side of the diffuser passage in the off-design flow condition. The numerical results revealed the typical vortical structure of the diffuser stall. The diffuser stall cell was caused by the systematic vortical structure which consisted of the tornado-type vortex, the longitudinal vortex at the shroud/suction surface corner (i.e., leading edge vortex (LEV, and the vortex in the throat area of the diffuser passages. Furthermore, the stage stall, which rotated within both the impeller and diffuser passages, occurred instead of the diffuser stall as the mass flow rate was decreased. According to the velocity measurements at the diffuser inlet, the diffuser stall which rotated on the shroud side was shifted to the hub side. Then, the diffuser stall moved into the impeller passages and formed the stage stall. Therefore, the stage stall was caused by the development of the diffuser stall, which transferred from the shroud side to the hub side in the vaneless space and expanded to the impeller passages.

  6. Adapted diffusion processes for effective forging dies

    Science.gov (United States)

    Paschke, H.; Nienhaus, A.; Brunotte, K.; Petersen, T.; Siegmund, M.; Lippold, L.; Weber, M.; Mejauschek, M.; Landgraf, P.; Braeuer, G.; Behrens, B.-A.; Lampke, T.

    2018-05-01

    Hot forging is an effective production method producing safety relevant parts with excellent mechanical properties. The economic efficiency directly depends on the occurring wear of the tools, which limits service lifetime. Several approaches of the presenting research group aim at minimizing the wear caused by interacting mechanical and thermal loads by using enhanced nitriding technology. Thus, by modifying the surface zone layer it is possible to create a resistance against thermal softening provoking plastic deformation and pronounced abrasive wear. As a disadvantage, intensely nitrided surfaces may possibly include the risk of increased crack sensitivity and therefore feature the chipping of material at the treated surface. Recent projects (evaluated in several industrial applications) show the high technological potential of adapted treatments: A first approach evaluated localized treatments by preventing areas from nitrogen diffusion with applied pastes or other coverages. Now, further ideas are to use this principle to structure the surface with differently designed patterns generating smaller ductile zones beneath nitrided ones. The selection of suitable designs is subject to certain geo-metrical requirements though. The intention of this approach is to prevent the formation and propagation of cracks under thermal shock conditions. Analytical characterization methods for crack sensitivity of surface zone layers and an accurate system of testing rigs for thermal shock conditions verified the treatment concepts. Additionally, serial forging tests using adapted testing geometries and finally, tests in the industrial production field were performed. Besides stabilizing the service lifetime and decreasing specific wear mechanisms caused by thermal influences, the crack behavior was influenced positively. This leads to a higher efficiency of the industrial production process and enables higher output in forging campaigns of industrial partners.

  7. Process for producing a porous diffusion membrane

    International Nuclear Information System (INIS)

    Kabayama, Shisho; Ikeda, Hirosaka.

    1969-01-01

    A diffusion membrane having a sandwich construction, the pore diameter of which is 1,000A or less, is provided for the separation and enrichment of, for example, U-235F from U-238F. Flexibility, corrosion resistance and separation efficiency of the barrier are improved by a process which comprises the steps of filling powders of metallic or inorganic materials into a mesh or grid-like support, superimposing onto the filled support a fluorine resin sheet consisting of a fluorine resin and a liquid foaming agent so that the outermost layers are the fluorine resin sheets, adhering them by applying a pressure of 30 to 30,000kg/cm 2 , and removing the foaming agent. Particle size of the powders may be 0.3 microns or less, but preferably 0.1 microns or less. Gold, silver, copper, platinum, nickel, monel metal, stainless steel, alumina and the like can be used with or without fluorine treatment. The powders are filled in the support by slip casting, rolling or electrophoresis. In one example, 100 parts by weight of polytetrafluoroethylene mixed with 50 parts of perfluoroalkane were compressed in a metallic die under a pressure of 25kg/cm 3 and were rolled to a thickness of 0.05m. A 250 mesh nickel wire filled with alumina particles having a diameter of 0.05 microns were compressed under 10 tons/cm 2 . The above sheets were laminated onto the nickel support on opposite surfaces, and thereafter pressed under a pressure of 100kg/cm 2 . The perfluoroalkane was removed. Argon isotope permeability of the product was 1.60 x 10 -5 mol/cm 2 .min.cmHg. The separation efficiency was 78%. (Iwakiri, K.)

  8. Differentiation of prostate cancer lesions with high and with low Gleason score by diffusion-weighted MRI

    Energy Technology Data Exchange (ETDEWEB)

    Barbieri, Sebastiano; Broennimann, Michael; Vermathen, Peter; Thoeny, Harriet C. [Inselspital University Hospital, Institute of Diagnostic, Pediatric, and Interventional Radiology, Bern (Switzerland); Boxler, Silvan [Inselspital, Inselspital University Hospital, Department of Urology, Bern (Switzerland)

    2017-04-15

    To differentiate prostate cancer lesions with high and with low Gleason score by diffusion-weighted-MRI (DW-MRI). This prospective study was approved by the responsible ethics committee. DW-MRI of 84 consenting prostate and/or bladder cancer patients scheduled for radical prostatectomy were acquired and used to compute apparent diffusion coefficient (ADC), intravoxel incoherent motion (IVIM: the pure diffusion coefficient D{sub t}, the pseudo-diffusion fraction F{sub p} and the pseudo-diffusion coefficient D{sub p}), and high b value (as acquired and Hessian filtered) parameters within the index lesion. These parameters (separately and combined in a logistic regression model) were used to differentiate lesions depending on whether whole-prostate histopathological analysis after prostatectomy determined a high (≥7) or low (6) Gleason score. Mean ADC and D{sub t} differed significantly (p of independent two-sample t test < 0.01) between high- and low-grade lesions. The highest classification accuracy was achieved by the mean ADC (AUC 0.74) and D{sub t} (AUC 0.70). A logistic regression model based on mean ADC, mean F{sub p} and mean high b value image led to an AUC of 0.74 following leave-one-out cross-validation. Classification by IVIM parameters was not superior to classification by ADC. DW-MRI parameters correlated with Gleason score but did not provide sufficient information to classify individual patients. (orig.)

  9. Usefulness of diffusion-weighted MRI in differentiating benign from malignant musculoskeletal tumors

    International Nuclear Information System (INIS)

    Nagata, Shuji; Uchida, Masafumi; Hayabuchi, Naofumi

    2005-01-01

    The purpose of this study was to evaluate the usefulness of diffusion-weighted MRI in distinguishing different components and in differentiating benign from malignant musculoskeletal tumors. Fifty-seven patients with musculoskeletal tumors underwent MR at our institution from October 1999 to April 2002. We evaluated 57 tumors (9 bone tumors and 48 soft tissue tumors). All tumors were classified into 8 groups (myxomatous, fibrous, cystic, cartilaginous, fatty components, hematomas, other benign tumors, and other malignant tumors). MR examinations were performed with a 1.5-Tesla system. Diffusion-weighted single-shot echo planer imaging (EPI) images were obtained in all patients. Apparent diffusion coefficients (ADCs) were calculated by using b factors of 0 and 1,000 sec/mm 2 . ADC values of myxomatous, cystic, and cartilaginous components were significantly higher than those of other tumors. In cartilaginous tumors, malignant tumor ADC values (2.33±0.44) were higher than those of benign tumors (2.13±0.13). However, there was no significant difference between benign and malignant tumors. Except for high-intensity components on T1-weighted imaging and low or homogeneously very high intensity components on T2-weighted imaging, there was a significant difference in ADC between malignant (1.35±0.40) and benign (1.97±0.50) tumors. Within the limited number of cases, there was a significant difference in ADC between malignant and benign tumors. (author)

  10. Anatomical and diffusion MRI of deep gray matter in pediatric spina bifida

    Directory of Open Access Journals (Sweden)

    Ashley L. Ware

    2014-01-01

    Full Text Available Individuals with spina bifida myelomeningocele (SBM exhibit brain abnormalities in cortical thickness, white matter integrity, and cerebellar structure. Little is known about deep gray matter macro- and microstructure in this population. The current study utilized volumetric and diffusion-weighted MRI techniques to examine gray matter volume and microstructure in several subcortical structures: basal ganglia nuclei, thalamus, hippocampus, and amygdala. Sixty-six children and adolescents (ages 8–18; M = 12.0, SD = 2.73 with SBM and typically developing (TD controls underwent T1- and diffusion-weighted neuroimaging. Microstructural results indicated that hippocampal volume was disproportionately reduced, whereas the putamen volume was enlarged in the group with SBM. Microstructural analyses indicated increased mean diffusivity (MD and fractional anisotropy (FA in the gray matter of most examined structures (i.e., thalamus, caudate, hippocampus, with the putamen exhibiting a unique pattern of decreased MD and increased FA. These results provide further support that SBM differentially disrupts brain regions whereby some structures are volumetrically normal whereas others are reduced or enlarged. In the hippocampus, volumetric reduction coupled with increased MD may imply reduced cellular density and aberrant organization. Alternatively, the enlarged volume and significantly reduced MD in the putamen suggest increased density.

  11. Probing region-specific microstructure of human cortical areas using high angular and spatial resolution diffusion MRI.

    Science.gov (United States)

    Aggarwal, Manisha; Nauen, David W; Troncoso, Juan C; Mori, Susumu

    2015-01-15

    Regional heterogeneity in cortical cyto- and myeloarchitecture forms the structural basis of mapping of cortical areas in the human brain. In this study, we investigate the potential of diffusion MRI to probe the microstructure of cortical gray matter and its region-specific heterogeneity across cortical areas in the fixed human brain. High angular resolution diffusion imaging (HARDI) data at an isotropic resolution of 92-μm and 30 diffusion-encoding directions were acquired using a 3D diffusion-weighted gradient-and-spin-echo sequence, from prefrontal (Brodmann area 9), primary motor (area 4), primary somatosensory (area 3b), and primary visual (area 17) cortical specimens (n=3 each) from three human subjects. Further, the diffusion MR findings in these cortical areas were compared with histological silver impregnation of the same specimens, in order to investigate the underlying architectonic features that constitute the microstructural basis of diffusion-driven contrasts in cortical gray matter. Our data reveal distinct and region-specific diffusion MR contrasts across the studied areas, allowing delineation of intracortical bands of tangential fibers in specific layers-layer I, layer VI, and the inner and outer bands of Baillarger. The findings of this work demonstrate unique sensitivity of diffusion MRI to differentiate region-specific cortical microstructure in the human brain, and will be useful for myeloarchitectonic mapping of cortical areas as well as to achieve an understanding of the basis of diffusion NMR contrasts in cortical gray matter. Copyright © 2014 Elsevier Inc. All rights reserved.

  12. Biophysical modeling of high field diffusion MRI demonstrates micro-structural aberration in chronic mild stress rat brain

    DEFF Research Database (Denmark)

    Khan, Ahmad Raza; Chuhutin, Andrey; Wiborg, Ove

    2016-01-01

    anhedonia is considered to be a realistic model of depression in studies of animal subjects. Stereological and neuronal tracing techniques have demonstrated persistent remodeling of microstructure in hippocampus, prefrontal cortex and amygdala of CMS brains. Recent developments in diffusion MRI (d...... microstructure in the hippocampus, prefrontal cortex, caudate putamen and amygdala regions of CMS rat brains by comparison to brains from normal controls. To validate findings of CMS induced microstructural alteration, histology was performed to determine neurite, nuclear and astrocyte density. d-MRI based...... neurite density and tensor-based mean kurtosis (MKT) were significantly higher, while mean diffusivity (MD), extracellular diffusivity (Deff) and intra-neurite diffusivity(DL) were significantly lower in the amygdala of CMS rat brains. Deff was also significantly lower in the hippocampus and caudate...

  13. Diffusion processes in the magnetopause boundary layer

    International Nuclear Information System (INIS)

    Tsurutani, B.T.; Thorne, R.M.

    1982-01-01

    Anomalous cross-field diffusion of magnetosheath ions and electrons is a direct consequence of cyclotron-resonant scattering by electrostatic and electromagnetic emissions which are continuously present within the magnetopause boundary layer. Expressions for the rate of cross-field diffusion involving either type of wave are developed and expressed in terms of the absolute upper limit referred to as Bohm diffusion. For the typical average intensity of waves observed in the boundary layer, resonant electron cross-field diffusion is always insignificant. However, magnetosheath ions, resonant with low frequency electrostatic waves, may be transported inward at a rate approaching one tenth the Bohm rate (D/sub perpendiculartsperpendicular/roughly-equal10 3 km 2 /s). While this is not the only mechanism capable of explaining the presence of the low latitude boundary layer it is adequate to account for the typical boundary layer thickness and it should occur at all local times and under all interplanetary conditions. It consequently provides a continuous mechanism for significant mass and momentum transfer across the magnetopause under conditions when field merging is inoperative

  14. Correlation of diffusion-weighted MRI and gross anatomy of rat kidneys

    International Nuclear Information System (INIS)

    Chen Rongfeng; Wu Xiaomei; Chen Xiaoyan; Deng Yu; Li Xinchun; He Jianxun; Li Huiming

    2011-01-01

    Objective: To investigate the feasibility and accuracy of diffusion-weighted MRI in differentiating the cortico-medullary layers of rat kidneys. Methods: Twelve rats underwent MRI using a 1.5 Tesla system including DWI of various b-values, T1WI and T 2 WI sequences. The MR characteristics and thickness of renal cortico-medullary layers compared to those of the gross anatomical layers. Results: On the longitudinal anatomical sections of the kidneys, four parenchymal layers of cortex (CO), the outer (OS) and inner (IS) stripes of the outer medulla (OM), the inner medulla (IM) and renal pelvis could be clearly recognized. The numbers of layers visible on MRI varied with different pulse sequences. Single layers of cortex and medulla were visible on T 1 WI. CO, OM and IM were delineated on T 2 WI. CO, OS, IS and IM were clearly identified on DWI and ADC maps. DWI was significantly superior to T 1 WI and T 2 WI for displaying the renal parenchymal layers (P 0.05) from the measurements on DWI (CO: 1.39±0.15 mm, OS: 1.01±0.17 mm, IS: 1.11±0.19 mm, IM: 1.06±0.10 mm). Different b-values of DWI did not show significant difference in depiction of the parenchyma (P>0.05). Conclusion: Four parenchymal layers shown on DWI correlated well with gross anatomical structure and may be used in imaging study of rat kidneys. (authors)

  15. Corticospinal MRI tractography in space-occupying brain lesions by diffusion tensor and kurtosis imaging methods

    Energy Technology Data Exchange (ETDEWEB)

    Leote, Joao [epartment of Neurosurgery, Hospital Garcia de Orta, Almada (Portugal); Institute of Biophysics and Biomedical Engineering, Faculty of Sciences of the University of Lisbon, Lisboa (Portugal); Nunes, Rita; Cerqueira, Luis; Ferreira, Hugo Alexandre [Institute of Biophysics and Biomedical Engineering, Faculty of Sciences of the University of Lisbon, Lisboa (Portugal)

    2015-05-18

    Recently, DKI-based tractography has been developed, showing improved crossing-fiber resolution in comparison to deterministic DTI-based tractography in healthy subjects. In this work, DTI and DKI-based tractography methods were compared regarding the assessment of the corticospinal tract in patients presenting space-occupying brain lesions near cortical motor areas. Nine patients (4 males) aged 23 to 62 years old, with space-occupying brain lesions (e.g. tumors) were studied for pre-surgical planning using a 1.5T MRI scanner and a 12-channel head coil. In 5 patients diffusion data was acquired along 64 directions and in 4 patients along 32 directions both with b-values 0, 1000 and 2000 s/mm2. Corticospinal tracts were estimated using deterministic DTI and DKI methods and also using probabilistic DTI. The superior cerebellar peduncles and the motor cortical areas, ipsilateral and contralateral to the lesions, were used as seed regions-of-interest for fiber tracking. Tracts courses and volumes were documented and compared between methods. Results showed that it was possible to estimate fiber tracts using deterministic DTI and DKI methods in 8/9 patients, and using the probabilistic DTI method in all patients. Overall, it was observed that DKI-based tractography showed more voluminous fiber tracts than when using deterministic DTI. The DKI method also showed curvilinear fibers mainly above lesions margins, which were not visible with deterministic DTI in 5 patients. Similar tracts were observed when using probabilistic DTI in 3 of those patients. Results suggest that the DKI method contribute with additional information about the corticospinal tract course in comparison with the DTI method, especially with subcortical lesions and near lesions’ margins. Therefore, this study suggests that DKI-based tractography could be useful in MRI and hybrid PET-MRI pre-surgical planning protocols for improved corticospinal tract evaluation.

  16. Independent value added by diffusion MRI for prediction of cognitive function in older adults

    Directory of Open Access Journals (Sweden)

    Julia A Scott

    2017-01-01

    Full Text Available The purpose of this study was to determine whether white matter microstructure measured by diffusion magnetic resonance imaging (dMRI provides independent information about baseline level or change in executive function (EF or memory (MEM in older adults with and without cognitive impairment. Longitudinal data was acquired from the Alzheimer's Disease Neuroimaging Initiative (ADNI study from phases GO and 2 (2009–2015. ADNI participants included were diagnosed as cognitively normal (n = 46, early mild cognitive impairment (MCI (n = 48, late MCI (n = 29, and dementia (n = 39 at baseline. We modeled the association between dMRI-based global white matter mean diffusivity (MD and baseline level and change in EF and MEM composite scores, in models controlling for baseline bilateral hippocampal volume, regional cerebral FDG PET metabolism and global cerebral AV45 PET uptake. EF and MEM composite scores were measured at baseline, 6, 12, 24 and 36 months. In the baseline late MCI and dementia groups, greater global MD was associated with lesser baseline EF, but not EF change nor MEM baseline or change. As expected, lesser hippocampal volume and lesser FDG PET metabolism was associated with greater rates of EF and MEM decline. In ADNI-GO/2 participants, white matter integrity provided independent information about current executive function, but was not sensitive to future cognitive change. Since individuals experiencing executive function declines progress to dementia more rapidly than those with only memory impairment, better biomarkers of future executive function decline are needed.

  17. Median nerve cross-sectional area and MRI diffusion characteristics: normative values at the carpal tunnel

    International Nuclear Information System (INIS)

    Yao, Lawrence; Gai, Neville

    2009-01-01

    Enlargement of the median nerve is an objective potential imaging sign of carpal tunnel syndrome. Diffusion tensor MRI (DTI) may provide additional structural information that may prove useful in characterizing median neuropathy. This study further examines normal values for median nerve cross-sectional area (CSA), apparent diffusion coefficient (ADC), and fractional anisotropy (FA). Twenty-three wrists in 17 healthy volunteers underwent MRI of the wrist at 3 T. In 13 subjects, DTI was performed at a B value of 600 mm 2 /s. Median nerve CSA, ADC, and FA were analyzed at standardized anatomic levels. Mean (SD) median nerve CSA within the proximal carpal tunnel was 10.0 (3.4) mm 2 . The mean (SD) FA of the median nerve was 0.71 (0.06) and 0.70 (0.13) proximal to and within the carpal tunnel, respectively. There was a significant difference between nerve CSA and ADC, but not FA, at the distal forearm and proximal carpal tunnel. Nerve CSA, ADC, and FA did not differ between men and women or between dominant and non-dominant wrists. Nerve CSA at the proximal carpal tunnel was positively correlated with subject age and body mass index. Our results suggest a 90% upper confidence limit for normal median nerve CSA of 14.4 mm 2 at the proximal carpal tunnel, higher than normal limits reported by many ultrasound studies. We observed a difference between the CSA and ADC, but not the FA, of the median nerve at the distal forearm and proximal carpal tunnel levels. (orig.)

  18. Child dermoid cyst mimicking a craniopharyngioma: the benefit of MRI T2-weighted diffusion sequence.

    Science.gov (United States)

    Amelot, Aymeric; Borha, Alin; Calmon, Raphael; Barbet, Patrick; Puget, Stephanie

    2018-02-01

    Brain dermoid cysts are very rare lesions. Although benign, these cysts may be associated with devastating complications due to mass effect or meningitis. The discovery of completely asymptomatic dermoid cysts in the pediatric population is exceedingly rare. Despite the advances in imaging modalities, it sometimes remains difficult to exclude the differential diagnosis of craniopharyngioma. We describe a 12-year-old boy addressed for suspicion of craniopharyngioma diagnosed by decreased visual acuity, bitemporal hemianopia and a CT scan showing a large hypodense suprasellar lesion with intralesional calcifications. Despite the unusual localization and size of this lesion, the absence of dermal sinus commonly found, and before visualizing a hyperintense mass on MRI-diffusion, the diagnosis of craniopharyngioma was ruled out in favor of a dermoid cyst. Radical excision was performed. In the suprasellar area, craniopharyngioma and dermoid cyst may have very similar radiological aspects: low density masses on CT scan and a hyperintense signal on T1-weighted MRI sequences with a variable signal on T2-weighted sequences. Hitherto, only two cases in literature have described suprasellar dermoid cyst. Their initial diagnosis was facilitated by the presence of a dermal sinus.

  19. Analysis of diffuse brain injury with primary brainstem lesion on MRI

    International Nuclear Information System (INIS)

    Shibata, Masayoshi; Matsumae, Mitsunori; Shimoda, Masami; Ishizaka, Hideo; Shiramizu, Hideki; Morita, Seiji; Tsugane, Ryuichi

    2003-01-01

    It has been reported that diffuse brain injury patients with primary brainstem lesions have a poor prognosis. Predicting the existence of brainstem injury at hospital arrival is problematic in actual clinical practice. We conducted magnetic resonance imaging (MRI), to visualize brainstem lesions clearly, and retrospectively analyzed predictive factors of brainstem lesions by stepwise multiple logistic regression analysis of patient characteristics, neurological findings, laboratory data, and CT findings at arrival in each case. We compared 24 patients with brainstem lesion and 60 without using MRI obtained less than 3 weeks after admission. Items investigated were blood pressure immediately after hospital arrival, arterial blood gas analysis, existence of abnormal respiration, blow direction, Glasgow coma scale (GCS), light reflex, oculocephalic reflex, corneal reflex, intracranial pressure, jugular venous oxygen saturation, and CT findings such as existence of subarachnoid hemorrhage at the suprasellar cistern, perimesencephalic cistern and convexity, lesions on the thalamus and basal ganglia, gliding contusion, intraventricular hemorrhage and Traumatic Coma Data Bank classification. Independent predictive factors of primary brainstem lesion included impaired light reflex (odds ratio: 2.269), subarachnoid hemorrhage at convexity (odds ratio: 3.592) and suprasellar cistern (odds ratio: 2.458), and Traumatic Coma Data Bank group III (odds ratio: 11.062). (author)

  20. Bevacizumab treatment in malignant meningioma with additional radiation necrosis. An MRI diffusion and perfusion case study

    Energy Technology Data Exchange (ETDEWEB)

    Bostroem, J.P. [University of Bonn Medical Center, Department of Neurosurgery, Bonn (Germany); MediClin Robert Janker Clinic and MVZ MediClin, Department of Radiosurgery and Stereotactic Radiotherapy, Bonn (Germany); Seifert, M.; Greschus, S. [University of Bonn Medical Center, Department of Radiology, Bonn (Germany); Schaefer, N.; Herrlinger, U. [University of Bonn Medical Center, Division of Clinical Neurooncology, Department of Neurology, Bonn (Germany); Glas, M. [University of Bonn Medical Center, Division of Clinical Neurooncology, Department of Neurology, Bonn (Germany); University of Bonn Medical Center, Stem Cell Pathologies, Institute of Reconstructive Neurobiology, Bonn (Germany); MediClin Robert Janker Clinic, Clinical Cooperation Unit Neurooncology, Bonn (Germany); Lammering, G. [MediClin Robert Janker Clinic and MVZ MediClin, Department of Radiosurgery and Stereotactic Radiotherapy, Bonn (Germany); MediClin Robert Janker Clinic, Clinical Cooperation Unit Neurooncology, Bonn (Germany); Heinrich-Heine-University of Duesseldorf, Department of Radiotherapy and Radiation Oncology, Duesseldorf (Germany)

    2014-04-15

    Recently two retrospective cohort studies report efficacy of bevacizumab in patients with recurrent atypical and anaplastic meningioma. Another successful therapeutic option of bevacizumab seems to be treatment of cerebral radiation necrosis. However, the antiangiogenic effects in MRI diffusion and perfusion in meningiomas have not been previously described in detail. The objective of this research was to evaluate the clinical and MR imaging effects of bevacizumab in a malignant meningioma patient harboring additional cerebral radiation necrosis. We report the case of an 80-year-old woman who underwent bevacizumab therapy (5 mg/kg every 2 weeks for 2 months) for treatment of a symptomatic radiation necrosis in malignant meningiomatosis of World Health Organization (WHO) grade III. The patient was closely monitored with MRI including diffusion and perfusion studies. Upon bevacizumab therapy, the clinical situation was well stabilized over a period of 4 months until the patient unfortunately died due to pneumonia/septicemia probably unrelated to bevacizumab therapy. Consecutive MRI demonstrated 4 important aspects: (1) considerable decrease of the contrast medium (CM)-enhanced radiation necrosis, (2) mixed response with respect to the meningiomatosis with stable and predominantly growing tumor lesions, (3) a new diffusion-weighted imaging (DWI) lesion in a CM-enhanced tumor as described in gliomas, which we did not interpret as a response to bevacizumab therapy, and (4) new thrombembolic infarcts, which are a known side-effect of bevacizumab treatment. Bevacizumab is effective in the treatment of radiation necrosis. We could not confirm the potential antitumor effect of bevacizumab in this patient. However, we could describe several new radiographic effects of bevacizumab therapy in malignant meningioma. (orig.) [German] In zwei aktuellen retrospektiven Kohortenstudien konnte eine Wirksamkeit von Bevacizumab bei Patienten mit rezidivierenden atypischen und

  1. Diffusion-weighted MRI and fibroscan vs. histopathology for assessment of liver fibrosis in chronic HCV patients: (Pilot study

    Directory of Open Access Journals (Sweden)

    Ahmed Hosni Kamel Abdelmaksoud

    2015-06-01

    Conclusions: Diffusion MRI can distinguish non-fibrotic liver (F0 from advanced fibrosis (F3 and F4 but cannot be used to distinguish between the intermediate stages of fibrosis-fibroscan can differentiate between (F0, F1, F2 and (F3, F4.

  2. Validity of apparent diffusion coefficient hyperpolarized 3He-MRI using MSCT and pulmonary function tests as references

    DEFF Research Database (Denmark)

    Diaz, Sandra; Casselbrant, Ingrid; Piitulainen, Eeva

    2008-01-01

    PURPOSE: To compare apparent diffusion coefficient (ADC) measurements from hyperpolarized (HP) helium ((3)He)-magnetic resonance imaging (MRI) with quantitative data from multislice Computed Tomography (CT) (MSCT) of the whole lungs and pulmonary function tests (PFT). MATERIALS AND METHODS: Twenty......-seven subjects, 22 with established emphysema and 5 with preclinical emphysema defined by PFT criteria, were examined with HP (3)He-MRI and MSCT. Mean age was 55 (+/-12) years, 18 female and 9 male. Mean ADC from (3)He-MRI was compared with emphysema index (EI), 15th percentile and mean lung density (MLD) values...... from MSCT. Both mean ADC and MSCT data were compared to PFT, especially percent of predicted diffusing capacity of carbon monoxide (%predicted DLCO), using Pearson's correlation test. RESULTS: Mean ADC and standard deviation values were 0.392+/-0.119 cm(2)/s for the established emphysema group and 0...

  3. Distortion-free diffusion MRI using an MRI-guided Tri-Cobalt 60 radiotherapy system: Sequence verification and preliminary clinical experience.

    Science.gov (United States)

    Gao, Yu; Han, Fei; Zhou, Ziwu; Cao, Minsong; Kaprealian, Tania; Kamrava, Mitchell; Wang, Chenyang; Neylon, John; Low, Daniel A; Yang, Yingli; Hu, Peng

    2017-10-01

    Monitoring tumor response during the course of treatment and adaptively modifying treatment plan based on tumor biological feedback may represent a new paradigm for radiotherapy. Diffusion MRI has shown great promises in assessing and predicting tumor response to radiotherapy. However, the conventional diffusion-weighted single-shot echo-planar-imaging (DW-ssEPI) technique suffers from limited resolution, severe distortion, and possibly inaccurate ADC at low field strength. The purpose of this work was to develop a reliable, accurate and distortion-free diffusion MRI technique that is practicable for longitudinal tumor response evaluation and adaptive radiotherapy on a 0.35 T MRI-guided radiotherapy system. A diffusion-prepared turbo spin echo readout (DP-TSE) sequence was developed and compared with the conventional diffusion-weighted single-shot echo-planar-imaging sequence on a 0.35 T MRI-guided radiotherapy system (ViewRay). A spatial integrity phantom was used to quantitate and compare the geometric accuracy of the two diffusion sequences for three orthogonal orientations. The apparent diffusion coefficient (ADC) accuracy was evaluated on a diffusion phantom under both 0 °C and room temperature to cover a diffusivity range between 0.40 × 10 -3 and 2.10 × 10 -3 mm 2 /s. Ten room temperature measurements repeated on five different days were conducted to assess the ADC reproducibility of DP-TSE. Two glioblastoma (GBM) and six sarcoma patients were included to examine the in vivo feasibility. The target registration error (TRE) was calculated to quantitate the geometric accuracy where structural CT or MR images were co-registered to the diffusion images as references. ADC maps from DP-TSE and DW-ssEPI were calculated and compared. A tube phantom was placed next to patients not treated on ViewRay, and ADCs of this reference tube were also compared. The proposed DP-TSE passed the spatial integrity test (< 1 mm within 100 mm radius and < 2 mm within 175 mm radius

  4. Implementing diffusion-weighted MRI for body imaging in prospective multicentre trials. Current considerations and future perspectives

    Energy Technology Data Exchange (ETDEWEB)

    DeSouza, N.M.; Winfield, J.M.; Weller, A.; Papoutsaki, M.V.; Doran, S.J.; Collins, D.J. [Institute of Cancer Research and Royal Marsden NHS Foundation Trust, CRUK Cancer Imaging Centre, Surrey (United Kingdom); Waterton, J.C.; Jackson, A. [University of Manchester, Manchester Academic Health Sciences Institute, Manchester (United Kingdom); Fournier, L. [Universite Paris Descartes Sorbonne Paris Cite, Assistance Publique-Hopitaux de Paris, Hopital Europeen Georges Pompidou, Radiology Department, Paris (France); Sullivan, D. [Duke Comprehensive Cancer Institute, Durham, NC (United States); Chenevert, T. [University of Michigan Health System, Department of Radiology, Ann Arbor, MI (United States); Boss, M. [National Institute of Standards and Technology (NIST), Applied Physics Division, Boulder, CO (United States); Trattnig, S. [Medical University of Vienna, Department of Biomedical Imaging and Image Guided Therapy, Vienna (Austria); Liu, Y. [European Organisation for Research and Treatment of Cancer, Brussels (Belgium)

    2018-03-15

    For body imaging, diffusion-weighted MRI may be used for tumour detection, staging, prognostic information, assessing response and follow-up. Disease detection and staging involve qualitative, subjective assessment of images, whereas for prognosis, progression or response, quantitative evaluation of the apparent diffusion coefficient (ADC) is required. Validation and qualification of ADC in multicentre trials involves examination of i) technical performance to determine biomarker bias and reproducibility and ii) biological performance to interrogate a specific aspect of biology or to forecast outcome. Unfortunately, the variety of acquisition and analysis methodologies employed at different centres make ADC values non-comparable between them. This invalidates implementation in multicentre trials and limits utility of ADC as a biomarker. This article reviews the factors contributing to ADC variability in terms of data acquisition and analysis. Hardware and software considerations are discussed when implementing standardised protocols across multi-vendor platforms together with methods for quality assurance and quality control. Processes of data collection, archiving, curation, analysis, central reading and handling incidental findings are considered in the conduct of multicentre trials. Data protection and good clinical practice are essential prerequisites. Developing international consensus of procedures is critical to successful validation if ADC is to become a useful biomarker in oncology. (orig.)

  5. Diffusion-weighted MRI of epithelial ovarian cancers: Correlation of apparent diffusion coefficient values with histologic grade and surgical stage

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Ji-Won, E-mail: fromentin@naver.com [Department of Radiology, Seoul St. Mary' s Hospital, College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul 137-701 (Korea, Republic of); Rha, Sung Eun, E-mail: serha@catholic.ac.kr [Department of Radiology, Seoul St. Mary' s Hospital, College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul 137-701 (Korea, Republic of); Oh, Soon Nam, E-mail: hiohsn@catholic.ac.kr [Department of Radiology, Seoul St. Mary' s Hospital, College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul 137-701 (Korea, Republic of); Park, Michael Yong, E-mail: digirave@kmle.com [Department of Radiology, Seoul St. Mary' s Hospital, College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul 137-701 (Korea, Republic of); Byun, Jae Young, E-mail: jybyun@catholic.ac.kr [Department of Radiology, Seoul St. Mary' s Hospital, College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul 137-701 (Korea, Republic of); Lee, Ahwon, E-mail: klee@catholic.ac.kr [Department of Hospital Pathology, Seoul St. Mary' s Hospital, College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul 137-701 (Korea, Republic of)

    2015-04-15

    Highlights: •The solid component of all invasive epithelial cancers showed high b{sub 1000} signal intensity. •ADCs can predict the histologic grade of epithelial ovarian cancer. •ADCs correlate negatively to the surgical stage of epithelial ovarian cancer. •ADCs may be useful imaging biomarkers to assess epithelial ovarian cancer. -- Abstract: Objective: The purpose of this article is to correlate the apparent diffusion coefficient (ADC) values of epithelial ovarian cancers with histologic grade and surgical stage. Materials and methods: We enrolled 43 patients with pathologically proven epithelial ovarian cancers for this retrospective study. All patients underwent preoperative pelvic magnetic resonance imaging (MRI) including diffusion-weighted images with b value of 0 and 1000 s/mm{sup 2} at 3.0-T unit. The mean ADC values of the solid portion of the tumor were measured and compared among different histologic grades and surgical stages. Results: The mean ADC values of epithelial ovarian cancers differed significantly between grade 1 (well-differentiated) and grade 2 (moderately-differentiated) (P = 0.013) as well as between grade 1 and grade 3 (poorly-differentiated) (P = 0.01); however, no statistically significant difference existed between grade 2 and grade 3 (P = 0.737). The receiver-operating characteristic analysis indicated that a cutoff ADC value of less than or equal to 1.09 × 10{sup −3} mm{sup 2}/s was associated with 94.4% sensitivity and 85.7% specificity in distinguishing grade 1 and grade 2/3 cancer. The difference in mean ADC values was statistically significant for early stage (FIGO stage I) and advanced stage (FIGO stage II-IV) cancer (P = 0.011). The interobserver agreement for the mean ADC values of epithelial ovarian cancers was excellent. Conclusion: The mean ADC values of the solid portion of epithelial ovarian cancers negatively correlated to histologic grade and surgical stage. The mean ADC values may be useful imaging

  6. Clinical usefulness of diffusion-weighted MRI in various stages of ischemic stroke

    International Nuclear Information System (INIS)

    Song, So Youne; Cho, Woo Ho; Kim, Soung Hee; Kim, Jung Sook; Kim, Young Hoon; Kim, Myung Gyu; Hur, Gham

    2002-01-01

    Diffusion-weighted MRI (DWI) is well known to be sensitive in the detection of hyperacute infarct, but has not been systematically investigated in patients with acute or subacute infarct. We evaluated the usefulness of diffusion-weighted MRI in assessing the various stages of brain infarct. Fifty-five consecutive patients with symptoms of brain infarct underwent fast spinecho T2-weighted MRI (T2WI) and DWI. Using only a brief clinical history, two radiologists first attempted to detect the lesion using T2W1, which was then compared with DWI. The usefulness of the latter was then evaluated in terms of the following criteria: 1) Its abilility to detect a lesion not seen at T2WI(detection); 2) localization of the responsible ischemic focus among multiple high-signal intensities seen at T2WI (localization); 3) conspicuity of a lesion which was subtle at T2WI (conspicuity); 4) detection of multiple lesions (multiplicity). DWI was useful in 44 of 55 patients (80%), including 9 of 9 (100%) with hyperacute infarct (<6 hours), 20 of 27 (74%) with acute infarct (<48 hours), and 15 of 19 (79%) with subacute infarct (<2 weeks). Among the nine patients at the hyperacute stage, DWI was useful for detection of the lesion in six (67%), for localization, 4 (44%) in one (11%), for conspicuity in four (44%), and for multiplicity in five (56%); at the acute stage (20 patients), for detection in three (15%), for localization in ten (50%), for conspicuity in eight (40%), and for moltiplicity in five (25%); and at the subacute stage (15 patients), for detection in three (20%), for localization in nine (60%), for conspicuity in two (13%), and for multiplicity in three (20%). DWI is very sensitive for the diagnosis of hyperacute infarct. In the assessment of this, it is useful during the acute or subacute period for the detection of small lesions, the localization of ongoing lesions among multiple high signal intensities seen at T2WI, and the determination of lesion conspicuity

  7. Diffusion-weighted MRI - a new parameter for advanced rectal carcinoma?

    International Nuclear Information System (INIS)

    Hein, P.A.; Lukas, P.; DeVries, A.F.; Pfeiffer, K.-P.

    2003-01-01

    Purpose: To evaluate the predictive value of apparent diffusion coefficient (ADC) on therapy outcome of combined chemoradiation in patients with primary carcinoma of the rectum. Materials and Method: Prior to standardized, combined, neoadjuvant chemoradiation, 16 patients with primary carcinoma of the rectum (cT3) were examined with magnetic resonance imaging (MRI). Diffusion weighted spin echo echo-planar images (SE-EPI) and contrast-enhanced T 1 -weighted spin echo (SE) images at 1.5 Tesla were obtained. The mean ADC of the tumor region was calculated and correlated with the therapy outcome substantiated by postsurgical histopathologic staging. Results: Tumor downstaging (pT0-2) occurred in 9 patients (therapy responders) and no down-staging (pT3) in 7 patients (therapy non-responders). The mean ADC measured 0.476±0.114 x 10 -3 mm 2 /s in the responder group and 0.703±0.085 x 10 -3 mm 2 /s in the non-responder group. Comparison of the mean ADC between the groups reached statistical significance (p=0.001). Conclusion: The mean ADC might be a new quantitative parameter to predict therapy outcome of combined preoperative chemoradiation in patients with primary carcinoma of the rectum. (orig.) [de

  8. Characterization of ductal carcinoma in situ on diffusion weighted breast MRI

    International Nuclear Information System (INIS)

    Rahbar, Habib; Partridge, Savannah C.; Eby, Peter R.; DeMartini, Wendy B.; Gutierrez, Robert L.; Peacock, Sue; Lehman, Constance D.

    2011-01-01

    To characterize ductal carcinoma in situ (DCIS) and its subtypes on diffusion-weighted imaging (DWI). We retrospectively reviewed 74 pure DCIS lesions in 69 women who underwent DWI at 1.5 T (b = 0 and 600 s/mm 2 ). Each lesion was characterized by qualitative DWI intensity, quantitative DWI lesion-to-normal contrast-to-noise ratio (CNR), and quantitative apparent diffusion coefficient (ADC). The detection rate was calculated with predetermined thresholds for each parameter. The effects of lesion size, grade, morphology, and necrosis were assessed. Ninety-six percent (71/74) of DCIS lesions demonstrated greater qualitative DWI intensity than normal breast tissue. Quantitatively, DCIS lesions demonstrated on average 56% greater signal than normal tissue (mean CNR = 1.83 ± 2.7) and lower ADC values (1.50 ± 0.28 x 10 -3 mm 2 /s) than normal tissue (2.01 ± 0.37 x 10 -3 mm 2 /s, p -3 mm 2 /s). Non-high-grade DCIS exhibited greater qualitative DWI intensity (p = 0.02) and quantitative CNR (p = 0.01) than high-grade DCIS but no difference in ADC (p = 0.40). Lesion size, morphology, and necrosis did not affect qualitative or quantitative DWI parameters of DCIS lesions (p > 0.05). DCIS lesions have higher DWI signal intensity and lower ADC values than normal breast tissue. DWI warrants further investigation as a potential non-contrast MRI tool for early breast cancer detection. (orig.)

  9. Patterns in early diffusion-weighted MRI in children with haemolytic uraemic syndrome and CNS involvement

    International Nuclear Information System (INIS)

    Donnerstag, Frank; Ding, Xiaoqi; Bueltmann, Eva; Zajaczek, Jan; Lanfermann, Heinrich; Pape, Lars; Das, Anibh Martin; Ehrich, Jochen; Hartmann, Hans; Luecke, Thomas; Hoy, Ludwig

    2012-01-01

    Diffusion-weighted imaging (DWI) in children with diarrhoea associated haemolytic uraemic syndrome (D+HUS) and cerebral involvement was evaluated retrospectively. DWI within 24 h of onset of neurological symptoms. The apparent diffusion coefficient (ADC) was measured in grey/white matter and correlated with clinical and laboratory findings. DWI was abnormal in all. Abnormal ADC was detected in the supratentorial white matter (6/12) and cortex (1/12), the basal ganglia (5/12), the thalami (4/12), and the cerebellum (1/12). ADC was reduced in 5/12, increased in 4/12, and both in 3/12. Mean serum sodium was lower in patients with DWI abnormalities affecting the white matter (6/12), than in those with basal ganglia/thalamic involvement (6/12). Neurological outcome was normal in 4/11 and abnormal in 7/11, and 1 patient died, outcome did not correlate to either localisation or type of DWI abnormality. In D+HUS with neurological symptoms, early DWI may reveal abnormal ADC not only in the basal ganglia/thalami, but also in the white matter/cortex. Besides thrombotic microangiopathy, toxic effects of shiga toxin, azotaemia and hyponatraemia / hypoosmolality may be involved in cerebral involvement in children with D+HUS. Findings on early MRI seem not to predict clinical course or outcome. (orig.)

  10. The use of MRI apparent diffusion coefficient (ADC in monitoring the development of brain infarction

    Directory of Open Access Journals (Sweden)

    Yuan Jian-Jun

    2011-01-01

    Full Text Available Abstract Background To study the rules that apparent diffusion coefficient (ADC changes with time and space in cerebral infarction, and to provide the evidence in defining the infarction stages. Methods 117 work-ups in 98 patients with cerebral infarction (12 hyperacute, 43 acute, 29 subacute, 10 steady, and 23 chronic infarctions were imaged with both conventional MRI and diffusion weighted imaging. The average ADC values, the relative ADC (rADC values, and the ADC values or rADC values from the center to the periphery of the lesion were calculated. Results The average ADC values and the rADC values of hyperacute and acute infarction lesion depressed obviously. rADC values in hyperacute and acute stage was minimized, and increased progressively as time passed and appeared as "pseudonormal" values in approximately 8 to 14 days. Thereafter, rADC values became greater than normal in chronic stage. There was positive correlation between rADC values and time (P Conclusion The ADC values of infarction lesions have evolution rules with time and space. The evolution rules with time and those in space can be helpful to decide the clinical stage, and to provide the evidence in guiding the treatment or judging the prognosis in infarction.

  11. Patterns in early diffusion-weighted MRI in children with haemolytic uraemic syndrome and CNS involvement

    Energy Technology Data Exchange (ETDEWEB)

    Donnerstag, Frank; Ding, Xiaoqi; Bueltmann, Eva; Zajaczek, Jan; Lanfermann, Heinrich [Hannover Medical School, Institute of Diagnostic and Therapeutic Neuroradiology, Hannover (Germany); Pape, Lars; Das, Anibh Martin; Ehrich, Jochen; Hartmann, Hans [Hannover Medical School, Clinic for Pediatric Kidney, Liver and Metabolic Diseases, Hannover (Germany); Luecke, Thomas [Hannover Medical School, Clinic for Pediatric Kidney, Liver and Metabolic Diseases, Hannover (Germany); University of Bochum, Department of Neuropediatrics, Pediatric Hospital, Bochum (Germany); Hoy, Ludwig [Hannover Medical School, Institute of Biometrics, Hannover (Germany)

    2012-03-15

    Diffusion-weighted imaging (DWI) in children with diarrhoea associated haemolytic uraemic syndrome (D+HUS) and cerebral involvement was evaluated retrospectively. DWI within 24 h of onset of neurological symptoms. The apparent diffusion coefficient (ADC) was measured in grey/white matter and correlated with clinical and laboratory findings. DWI was abnormal in all. Abnormal ADC was detected in the supratentorial white matter (6/12) and cortex (1/12), the basal ganglia (5/12), the thalami (4/12), and the cerebellum (1/12). ADC was reduced in 5/12, increased in 4/12, and both in 3/12. Mean serum sodium was lower in patients with DWI abnormalities affecting the white matter (6/12), than in those with basal ganglia/thalamic involvement (6/12). Neurological outcome was normal in 4/11 and abnormal in 7/11, and 1 patient died, outcome did not correlate to either localisation or type of DWI abnormality. In D+HUS with neurological symptoms, early DWI may reveal abnormal ADC not only in the basal ganglia/thalami, but also in the white matter/cortex. Besides thrombotic microangiopathy, toxic effects of shiga toxin, azotaemia and hyponatraemia / hypoosmolality may be involved in cerebral involvement in children with D+HUS. Findings on early MRI seem not to predict clinical course or outcome. (orig.)

  12. Optimising diffusion weighted MRI for imaging metastatic and myeloma bone disease and assessing reproducibility

    International Nuclear Information System (INIS)

    Messiou, C.; Collins, D.J.; Morgan, V.A.; DeSouza, N.M.

    2011-01-01

    To establish normal bone marrow values of apparent diffusion coefficient (ADC) over an age range, compare them with metastatic and myelomatous involvement, to establish reproducibility and to optimise b values. The ADCs of bone marrow in 7 volunteers (mean age 29.7 years), 34 volunteers (mean age 63.3 years) and 43 patients with metastatic and myelomatous involvement (mean age 65.5 years) were measured. In 9 volunteers diffusion weighted MRI was repeated within 7 days. b values were derived to optimise contrast between normal and pathological marrow. The mean ADC of bone marrow in younger volunteers was significantly higher than that of older volunteers. The coefficient of reproducibility was 14.8%. The ADC mean of metastatic and myeloma bone disease was 1054+/-456 x 10 -6 mm 2 s -1 . An ADC threshold of 655 x 10 -6 mm 2 s -1 separated normal and abnormal marrow with a sensitivity and specificity of 90% and 93% respectively. Contrast between normal and abnormal marrow was optimal at b = 1389 smm -2 . The reproducibility of ADC measurements in bone is equivalent to published data for soft tissue with a high sensitivity and specificity for separating abnormal from age matched normal bone marrow. A b value of around 1,400 smm -2 is optimal for imaging bone marrow. (orig.)

  13. Optimising diffusion weighted MRI for imaging metastatic and myeloma bone disease and assessing reproducibility

    Energy Technology Data Exchange (ETDEWEB)

    Messiou, C. [Institute of Cancer Research and Royal Marsden, NHS Foundation Trust, Cancer Research UK Clinical Magnetic Resonance Research Group, Surrey (United Kingdom); Institute of Cancer Research and Royal Marsden, NHS Foundation Trust, MRI Department, Surrey (United Kingdom); Collins, D.J.; Morgan, V.A.; DeSouza, N.M. [Institute of Cancer Research and Royal Marsden, NHS Foundation Trust, Cancer Research UK Clinical Magnetic Resonance Research Group, Surrey (United Kingdom)

    2011-08-15

    To establish normal bone marrow values of apparent diffusion coefficient (ADC) over an age range, compare them with metastatic and myelomatous involvement, to establish reproducibility and to optimise b values. The ADCs of bone marrow in 7 volunteers (mean age 29.7 years), 34 volunteers (mean age 63.3 years) and 43 patients with metastatic and myelomatous involvement (mean age 65.5 years) were measured. In 9 volunteers diffusion weighted MRI was repeated within 7 days. b values were derived to optimise contrast between normal and pathological marrow. The mean ADC of bone marrow in younger volunteers was significantly higher than that of older volunteers. The coefficient of reproducibility was 14.8%. The ADC mean of metastatic and myeloma bone disease was 1054+/-456 x 10{sup -6} mm{sup 2}s{sup -1}. An ADC threshold of 655 x 10{sup -6} mm{sup 2}s{sup -1} separated normal and abnormal marrow with a sensitivity and specificity of 90% and 93% respectively. Contrast between normal and abnormal marrow was optimal at b = 1389 smm{sup -2}. The reproducibility of ADC measurements in bone is equivalent to published data for soft tissue with a high sensitivity and specificity for separating abnormal from age matched normal bone marrow. A b value of around 1,400 smm{sup -2} is optimal for imaging bone marrow. (orig.)

  14. 4D flow mri post-processing strategies for neuropathologies

    Science.gov (United States)

    Schrauben, Eric Mathew

    4D flow MRI allows for the measurement of a dynamic 3D velocity vector field. Blood flow velocities in large vascular territories can be qualitatively visualized with the added benefit of quantitative probing. Within cranial pathologies theorized to have vascular-based contributions or effects, 4D flow MRI provides a unique platform for comprehensive assessment of hemodynamic parameters. Targeted blood flow derived measurements, such as flow rate, pulsatility, retrograde flow, or wall shear stress may provide insight into the onset or characterization of more complex neuropathologies. Therefore, the thorough assessment of each parameter within the context of a given disease has important medical implications. Not surprisingly, the last decade has seen rapid growth in the use of 4D flow MRI. Data acquisition sequences are available to researchers on all major scanner platforms. However, the use has been limited mostly to small research trials. One major reason that has hindered the more widespread use and application in larger clinical trials is the complexity of the post-processing tasks and the lack of adequate tools for these tasks. Post-processing of 4D flow MRI must be semi-automated, fast, user-independent, robust, and reliably consistent for use in a clinical setting, within large patient studies, or across a multicenter trial. Development of proper post-processing methods coupled with systematic investigation in normal and patient populations pushes 4D flow MRI closer to clinical realization while elucidating potential underlying neuropathological origins. Within this framework, the work in this thesis assesses venous flow reproducibility and internal consistency in a healthy population. A preliminary analysis of venous flow parameters in healthy controls and multiple sclerosis patients is performed in a large study employing 4D flow MRI. These studies are performed in the context of the chronic cerebrospinal venous insufficiency hypothesis. Additionally, a

  15. Use of diffusion-weighted imaging (DWI) in PET/MRI for head and neck cancer evaluation

    International Nuclear Information System (INIS)

    Queiroz, Marcelo A.; Schulthess, Gustav von; Huellner, Martin; Kuhn, Felix; Veit-Haibach, Patrick; Huber, Gerhardt; Meerwein, Christian; Kollias, Spyros

    2014-01-01

    The purpose of this study was to analyze whether diffusion-weighted imaging (DWI) adds significant information to positron emission tomography/magnetic resonance imaging (PET/MRI) on lesion detection and characterization in head and neck cancers. Seventy patients with different head and neck cancers were enrolled in this prospective study. All patients underwent sequential contrast-enhanced (ce) PET/computed tomography (CT) and cePET/MRI using a tri-modality PET/CT-MR setup either for staging or re-staging. First, the DWI alone was evaluated, followed by the PET/MRI with conventional sequences, and in a third step, the PET/MRI with DWI was evaluated. McNemar's test was used to evaluate differences in the accuracy of PET/MRI with and without DWI compared to the standard of reference. One hundred eighty-eight (188) lesions were found, and of those, 118 (62.8 %) were malignant and 70 (37.2 %) were benign. PET/MRI without DWI had a higher accuracy in detecting malignant lesions than DWI alone (86.8 % vs. 60.6 %, p < 0.001). PET/MRI combined with DWI detected 120 concurrent lesions (89 malignant and 31 benign), PET/MRI alone identified 48 additional lesions (20 malignant and 28 benign), and DWI alone detected 20 different lesions (nine malignant and 11 benign). However, lesions detected on DWI did not change overall staging. SUV maximum and mean were significantly higher in malignant lesions than in benign lesions. DWI parameters between malignant and benign lesions were not statistically different. The use of DWI as part of PET/MRI to evaluate head and neck cancers does not provide remarkable information. Thus, the use of DWI might not be needed in clinical PET/MRI protocols for the staging or restaging of head and neck cancers. (orig.)

  16. Diffusion processes in bombardment-induced surface topography

    International Nuclear Information System (INIS)

    Robinson, R.S.

    1984-01-01

    A treatment is given of the problem of surface diffusion processes occurring during surface topography development, whenever a surface is simultaneously seeded with impurities and ion bombarded. The development of controllable topography and the importance of surface diffusion parameters, which can be obtained during these studies, are also analyzed. 101 refs.; 7 figs.; 2 tabs

  17. "We noticed that suddenly the country has become full of MRI". Policy makers' views on diffusion and use of health technologies in Iran

    Directory of Open Access Journals (Sweden)

    Tishelman Carol

    2010-04-01

    Full Text Available Abstract Objective Uncontrolled proliferation of health technologies (HT is one contributor to the increasing pressure on health systems to adopt new technologies. With limited resources, policy-makers encounter difficulties in fulfilling their responsibility to meet the healthcare needs of the population. The aim of this study is to explore how policy-makers' reason about the diffusion and utilization of health technologies in Iran using magnetic resonance imaging (MRI and interferon beta as tracers. Method This qualitative exploration complements quantitative data generated in a research project investigating the diffusion and utilization of MRI and interferon beta in Iran. Qualitative semi-structured interviews were conducted with 13 informants in different positions and levels of authority in the Ministry of Health (MOH, University of Medical Sciences, Health Insurance Organizations, and Parliament. The data was analysed using the framework approach. Findings Although policy-makers appeared to be positive to health technology assessment (HTA, the processes of policy-making described by the interviewees did not seem to be based on a full understanding of this (discipline. Several obstacles to applying knowledge about HT and HTA were described. The current official plan for MRI adoption and diffusion in the country was said not to be followed, and no such plan was described for interferon beta. Instead, market forces such as advertising, and physician and consumer demand, appear to have strong influence on HT diffusion and use. Dual practice may have increased the induced demand and also reduced the supervision of the private sector by the MOH. Conclusion Management instability and lack of coordination in the MOH were found to be important obstacles to accumulation of knowledge and experience which, in turn, could have led to suboptimal managerial and policy-making processes. Furthermore marketing should be controlled in order to avoid

  18. Diffusive processes in a stochastic magnetic field

    International Nuclear Information System (INIS)

    Wang, H.; Vlad, M.; Vanden Eijnden, E.; Spineanu, F.; Misguich, J.H.; Balescu, R.

    1995-01-01

    The statistical representation of a fluctuating (stochastic) magnetic field configuration is studied in detail. The Eulerian correlation functions of the magnetic field are determined, taking into account all geometrical constraints: these objects form a nondiagonal matrix. The Lagrangian correlations, within the reasonable Corrsin approximation, are reduced to a single scalar function, determined by an integral equation. The mean square perpendicular deviation of a geometrical point moving along a perturbed field line is determined by a nonlinear second-order differential equation. The separation of neighboring field lines in a stochastic magnetic field is studied. We find exponentiation lengths of both signs describing, in particular, a decay (on the average) of any initial anisotropy. The vanishing sum of these exponentiation lengths ensures the existence of an invariant which was overlooked in previous works. Next, the separation of a particle's trajectory from the magnetic field line to which it was initially attached is studied by a similar method. Here too an initial phase of exponential separation appears. Assuming the existence of a final diffusive phase, anomalous diffusion coefficients are found for both weakly and strongly collisional limits. The latter is identical to the well known Rechester-Rosenbluth coefficient, which is obtained here by a more quantitative (though not entirely deductive) treatment than in earlier works

  19. Multidimensional epidemic thresholds in diffusion processes over interdependent networks

    International Nuclear Information System (INIS)

    Salehi, Mostafa; Siyari, Payam; Magnani, Matteo; Montesi, Danilo

    2015-01-01

    Highlights: •We propose a new concept of multidimensional epidemic threshold for interdependent networks. •We analytically derive and numerically illustrate the conditions for multilayer epidemics. •We study the evolution of infection density and diffusion dynamics. -- Abstract: Several systems can be modeled as sets of interdependent networks where each network contains distinct nodes. Diffusion processes like the spreading of a disease or the propagation of information constitute fundamental phenomena occurring over such coupled networks. In this paper we propose a new concept of multidimensional epidemic threshold characterizing diffusion processes over interdependent networks, allowing different diffusion rates on the different networks and arbitrary degree distributions. We analytically derive and numerically illustrate the conditions for multilayer epidemics, i.e., the appearance of a giant connected component spanning all the networks. Furthermore, we study the evolution of infection density and diffusion dynamics with extensive simulation experiments on synthetic and real networks

  20. fMRI paradigm designing and post-processing tools

    International Nuclear Information System (INIS)

    James, Jija S; Rajesh, PG; Chandran, Anuvitha VS; Kesavadas, Chandrasekharan

    2014-01-01

    In this article, we first review some aspects of functional magnetic resonance imaging (fMRI) paradigm designing for major cognitive functions by using stimulus delivery systems like Cogent, E-Prime, Presentation, etc., along with their technical aspects. We also review the stimulus presentation possibilities (block, event-related) for visual or auditory paradigms and their advantage in both clinical and research setting. The second part mainly focus on various fMRI data post-processing tools such as Statistical Parametric Mapping (SPM) and Brain Voyager, and discuss the particulars of various preprocessing steps involved (realignment, co-registration, normalization, smoothing) in these software and also the statistical analysis principles of General Linear Modeling for final interpretation of a functional activation result

  1. Prognostic significance of focal lesions and diffuse infiltration on MRI for multiple myeloma: a meta-analysis

    Energy Technology Data Exchange (ETDEWEB)

    Lee, So-Yeon; Park, Hee-Jin [Sungkyunkwan University School of Medicine, Department of Radiology, Kangbuk Samsung Hospital, Seoul (Korea, Republic of); Kim, Hyun-Jung [Korea University College of Medicine, Department of Preventive Medicine, Seoul (Korea, Republic of); Shin, Yu Ri [The Catholic University of Korea, Department of Radiology, Incheon St. Mary' s Hospital, College of Medicine, Seoul (Korea, Republic of); Lee, Yun-Gyoo; Oh, Suk Joong [Sungkyunkwan University School of Medicine, Division of Hematology and Oncology, Department of Internal Medicine, Kangbuk Samsung Hospital, Seoul (Korea, Republic of)

    2017-06-15

    MRI of bone marrow of the axial skeleton is recommended for evaluation of multiple myeloma. The impact of bone marrow involvement pattern on MRI for determining progression-free survival (PFS) and overall survival (OS) is not yet clear. We performed a meta-analysis of research on the prognostic significance of MRI patterns for OS and PFS using a random effects model. Databases searched without language restriction were MEDLINE, EMBASE, and the Cochrane Library (January 1976 to April 2014). Manual searches were also conducted. Of 10,953 citations identified in the original search, 10 cohort studies for a total of 2015 patients met the inclusion criteria. Nine of the 10 included studies are from three research groups. Pooled hazard ratios were 1.80 (95 % confidence interval [CI] 1.32-2.46; P < 0.001) for OS and 2.30 (95 % CI 1.65-3.20; P < 0.001) for PFS for focal lesions on MRI; and 1.70 (95 % CI 1.30-2.21; P < 0.001) for OS and 1.74 (95 % CI 1.07-2.85; P = 0.03) for PFS for diffuse infiltration on MRI. No significant heterogeneity was observed among studies. This meta-analysis demonstrated an association between focal lesions and diffuse infiltration and poor prognosis in this population. (orig.)

  2. What’s the clinical significance of adding diffusion and perfusion MRI in the differentiation of glioblastoma multiforme and solitary brain metastasis?

    Directory of Open Access Journals (Sweden)

    Amr F. Mourad

    2017-09-01

    Full Text Available Objective: To evaluate the additional diagnostic value of diffusion and perfusion MRI in the differentiation of glioblastoma multiforme (GBM and solitary brain metastasis. Patients and methods: This retrospective study included 24 patients with histologically proven brain tumors who underwent conventional MRI with analysis of diffusion (DWI and perfusion (PWI MRI findings of each tumor. The Apparent Diffusion Coefficient (ADC values were calculated in the minimum (ADC-MIN, mean (ADC-MEAN, and maximum (ADC-MAX in all the tumors and the peritumoral regions. The PWI data was expressed as maximum regional cerebral blood volume (rCBV of the tumors and peritumoral regions. Results: After adding diffusion and perfusion to conventional MRI findings, we found that the accuracy of differentiation between glioblastoma multiforme (GBM and solitary metastasis increased from 70% to 90%.There is a significant difference in DWI signal intensity between GBM and metastatic tumors (P < 0.05. The ADC values of GBM were lower than that of metastatic tumors. On perfusion MRI, the maximum rCBV of the peritumoral region (rCBVP of GBM was higher than that of brain metastases (P < 0.001. Conclusion: The addition of diffusion and perfusion to the MRI protocol increases the accuracy of differentiation between GBM and solitary brain metastasis and should be considered routinely. Keywords: Diffusion MRI, Perfusion MRI, GBM, Solitary brain metastases

  3. Ergodicity breaking, ageing, and confinement in generalized diffusion processes with position and time dependent diffusivity

    International Nuclear Information System (INIS)

    Cherstvy, Andrey G; Metzler, Ralf

    2015-01-01

    We study generalized anomalous diffusion processes whose diffusion coefficient D(x, t) ∼ D 0 |x| α t β depends on both the position x of the test particle and the process time t. This process thus combines the features of scaled Brownian motion and heterogeneous diffusion parent processes. We compute the ensemble and time averaged mean squared displacements of this generalized diffusion process. The scaling exponent of the ensemble averaged mean squared displacement is shown to be the product of the critical exponents of the parent processes, and describes both subdiffusive and superdiffusive systems. We quantify the amplitude fluctuations of the time averaged mean squared displacement as function of the length of the time series and the lag time. In particular, we observe a weak ergodicity breaking of this generalized diffusion process: even in the long time limit the ensemble and time averaged mean squared displacements are strictly disparate. When we start to observe this process some time after its initiation we observe distinct features of ageing. We derive a universal ageing factor for the time averaged mean squared displacement containing all information on the ageing time and the measurement time. External confinement is shown to alter the magnitudes and statistics of the ensemble and time averaged mean squared displacements. (paper)

  4. Minimum uncertainty and squeezing in diffusion processes and stochastic quantization

    Science.gov (United States)

    Demartino, S.; Desiena, S.; Illuminati, Fabrizo; Vitiello, Giuseppe

    1994-01-01

    We show that uncertainty relations, as well as minimum uncertainty coherent and squeezed states, are structural properties for diffusion processes. Through Nelson stochastic quantization we derive the stochastic image of the quantum mechanical coherent and squeezed states.

  5. Rotational and translational diffusions of fluorescent probes during gelation process

    Science.gov (United States)

    Hattori, Yusuke; Panizza, Pascal; Letamendia, Louis; Ushiki, Hideharu

    2006-04-01

    Gelation process has been investigated by using light scattering techniques in recent years. We measured both of rotational and translational motions of fluorescent probes during gelation process. The measurements were performed after the temperature quenched at 30 °C. As the results, rotational diffusion coefficient of fluorescein was decreased after 6.0 × 10 4 s and energy transfer rate was reduced after 2.0 × 10 4 s. We sorted the gelation process into the following three parts, (I) pre-gelation, (II) reduction of translational diffusion (aging), and (III) reduction of rotational diffusion with saturating translational diffusion (post-gelation). The time scale of the process was completely different from the results of other methods.

  6. MRI-Guided Diffuse Optical Spectroscopy of Malignant and Benign Breast Lesions

    Directory of Open Access Journals (Sweden)

    Vasilis Ntziachristos

    2002-01-01

    Full Text Available We present the clinical implementation of a novel hybrid system that combines magnetic resonance imaging (MRI and near-infrared (NIR optical measurements for the noninvasive study of breast cancer in vivo. Fourteen patients were studied with a MR-NIR prototype imager and spectrometer. A diffuse optical tomographic scheme employed the MR images as a priori information to implement an image-guided NIR localized spectroscopic scheme. All patients who entered the study also underwent gadolinium-enhanced MRI and biopsy so that the optical findings were crossvalidated with MR readings and histopathology. The technique quantified the oxy-and deoxyhemoglobin of five malignant and nine benign breast lesions in vivo. Breast cancers were found with decreased oxygen saturation and higher blood concentration than most benign lesions. The average hemoglobin concentration ([H] of cancers was 0.130±0.100 mM, and the average hemoglobin saturation (Y was 60±9% compared to [H]=0.018±0.005 mM and Y=69±6% of background tissue. Fibroadenomas exhibited high hemoglobin concentration [H]=0.060±0.010 mM and mild decrease in oxygen saturation Y=67±2%. Cysts and other normal lesions were easily differentiated based on intrinsic contrast information. This novel optical technology can be a significant add-on in MR examinations and can be used to characterize functional parameters of cancers with diagnostic and treatment prognosis potential. It is foreseen that the technique can play a major role in functional activation studies of brain and muscle as well.

  7. Strain Map of the Tongue in Normal and ALS Speech Patterns from Tagged and Diffusion MRI.

    Science.gov (United States)

    Xing, Fangxu; Prince, Jerry L; Stone, Maureen; Reese, Timothy G; Atassi, Nazem; Wedeen, Van J; El Fakhri, Georges; Woo, Jonghye

    2018-02-01

    Amyotrophic Lateral Sclerosis (ALS) is a neurological disease that causes death of neurons controlling muscle movements. Loss of speech and swallowing functions is a major impact due to degeneration of the tongue muscles. In speech studies using magnetic resonance (MR) techniques, diffusion tensor imaging (DTI) is used to capture internal tongue muscle fiber structures in three-dimensions (3D) in a non-invasive manner. Tagged magnetic resonance images (tMRI) are used to record tongue motion during speech. In this work, we aim to combine information obtained with both MR imaging techniques to compare the functionality characteristics of the tongue between normal and ALS subjects. We first extracted 3D motion of the tongue using tMRI from fourteen normal subjects in speech. The estimated motion sequences were then warped using diffeomorphic registration into the b0 spaces of the DTI data of two normal subjects and an ALS patient. We then constructed motion atlases by averaging all warped motion fields in each b0 space, and computed strain in the line of action along the muscle fiber directions provided by tractography. Strain in line with the fiber directions provides a quantitative map of the potential active region of the tongue during speech. Comparison between normal and ALS subjects explores the changing volume of compressing tongue tissues in speech facing the situation of muscle degradation. The proposed framework provides for the first time a dynamic map of contracting fibers in ALS speech patterns, and has the potential to provide more insight into the detrimental effects of ALS on speech.

  8. Ex-vivo diffusion MRI reveals microstructural alterations in stress-sensitive brain regions: A chronic mild stress recovery study

    DEFF Research Database (Denmark)

    Khan, Ahmad Raza; Hansen, Brian; Wiborg, Ove

    Depression is a leading cause of disability worldwide and causes significant microstructural alterations in stress-sensitive brain regions. However, the potential recovery of these microstructural alterations has not previously been investigated, which we, therefore, set out to do using diffusion...... MRI (d-MRI) in the chronic mild stress (CMS) rat model of depression. This study reveals significant microstructural alterations after 8 weeks of recovery, in the opposite direction to change induced by stress in the acute phase of the experiment. Such findings may be useful in the prognosis...... of depression or for monitoring treatment response....

  9. Differentiation between benign and malignant breast lesions using quantitative diffusion-weighted sequence on 3 T MRI

    International Nuclear Information System (INIS)

    Tan, S.L.L.; Rahmat, K.; Rozalli, F.I.; Mohd-Shah, M.N.; Aziz, Y.F.A.; Yip, C.H.; Vijayananthan, A.; Ng, K.H.

    2014-01-01

    Aim: To investigate the capability and diagnostic accuracy of diffusion-weighted imaging (DWI) in differentiating benign from malignant breast lesions using 3 T magnetic resonance imaging (MRI). Materials and methods: Women with suspicious or indeterminate breast lesions detected at MRI, mammogram and/or ultrasound were recruited for dynamic contrast-enhanced (DCE)-MRI and DWI prior to their biopsy. Image fusion of DCE-MRI with apparent diffusion coefficient (ADC) map was utilized to select the region of interest (ROI) for ADC calculation in the area that showed the most avid enhancement. DWI was performed using two sets of b-values at 500 and 1000 s/mm 2 , respectively. Results: Fifty women were recruited and the final analysis comprised 44 breast lesions, 31 of which were malignant and 13 were benign. Significant results were obtained between ADC values of benign and malignant lesions (p −3 mm 2 /s for b = 500 s/mm 2 and 1.22 × 10 −3 mm 2 /s for b = 1000 s/mm 2 , respectively. The sensitivity of DCE-MRI alone was 100% with a specificity of 66.7%. When DCE-MRI was combined with b = 1000 s/mm 2 , the specificity rose to 100%, while only mildly affecting sensitivity (90.6%). No significant correlation was found between ADC values and prognostic factors, such as lymph node metastasis, tumour size, oestrogen receptor (ER), progesterone receptor (PR), and human epidermal growth factor receptor 2 (HER2) status, and tumour grades. Conclusion: The present study provides consistent evidence to support DWI as a diagnostic tool for breast lesion characterization. A combination of DCE-MRI with DWI is suggested to improve the sensitivity and specificity of lesion characterization

  10. Separation of type and grade in cervical tumours using non-mono-exponential models of diffusion-weighted MRI

    International Nuclear Information System (INIS)

    Winfield, Jessica M.; Collins, David J.; Morgan, Veronica A.; DeSouza, Nandita M.; Orton, Matthew R.; Ind, Thomas E.J.; Attygalle, Ayoma; Hazell, Steve

    2017-01-01

    Assessment of empirical diffusion-weighted MRI (DW-MRI) models in cervical tumours to investigate whether fitted parameters distinguish between types and grades of tumours. Forty-two patients (24 squamous cell carcinomas, 14 well/moderately differentiated, 10 poorly differentiated; 15 adenocarcinomas, 13 well/moderately differentiated, two poorly differentiated; three rare types) were imaged at 3 T using nine b-values (0 to 800 s mm -2 ). Mono-exponential, stretched exponential, kurtosis, statistical, and bi-exponential models were fitted. Model preference was assessed using Bayesian Information Criterion analysis. Differences in fitted parameters between tumour types/grades and correlation between fitted parameters were assessed using two-way analysis of variance and Pearson's linear correlation coefficient, respectively. Non-mono-exponential models were preferred by 83 % of tumours with bi-exponential and stretched exponential models preferred by the largest numbers of tumours. Apparent diffusion coefficient (ADC) and diffusion coefficients from non-mono-exponential models were significantly lower in poorly differentiated tumours than well/moderately differentiated tumours. α (stretched exponential), K (kurtosis), f and D* (bi-exponential) were significantly different between tumour types. Strong correlation was observed between ADC and diffusion coefficients from other models. Non-mono-exponential models were preferred to the mono-exponential model in DW-MRI data from cervical tumours. Parameters of non-mono-exponential models showed significant differences between types and grades of tumours. (orig.)

  11. Separation of type and grade in cervical tumours using non-mono-exponential models of diffusion-weighted MRI

    Energy Technology Data Exchange (ETDEWEB)

    Winfield, Jessica M.; Collins, David J.; Morgan, Veronica A.; DeSouza, Nandita M. [The Royal Marsden NHS Foundation Trust, MRI Unit, Sutton, Surrey (United Kingdom); The Institute of Cancer Research, Cancer Research UK Cancer Imaging Centre, Division of Radiotherapy and Imaging, London (United Kingdom); Orton, Matthew R. [The Institute of Cancer Research, Cancer Research UK Cancer Imaging Centre, Division of Radiotherapy and Imaging, London (United Kingdom); Ind, Thomas E.J. [The Royal Marsden NHS Foundation Trust, Gynaecology Unit, London (United Kingdom); Attygalle, Ayoma; Hazell, Steve [The Royal Marsden NHS Foundation Trust, Department of Histopathology, London (United Kingdom)

    2017-02-15

    Assessment of empirical diffusion-weighted MRI (DW-MRI) models in cervical tumours to investigate whether fitted parameters distinguish between types and grades of tumours. Forty-two patients (24 squamous cell carcinomas, 14 well/moderately differentiated, 10 poorly differentiated; 15 adenocarcinomas, 13 well/moderately differentiated, two poorly differentiated; three rare types) were imaged at 3 T using nine b-values (0 to 800 s mm{sup -2}). Mono-exponential, stretched exponential, kurtosis, statistical, and bi-exponential models were fitted. Model preference was assessed using Bayesian Information Criterion analysis. Differences in fitted parameters between tumour types/grades and correlation between fitted parameters were assessed using two-way analysis of variance and Pearson's linear correlation coefficient, respectively. Non-mono-exponential models were preferred by 83 % of tumours with bi-exponential and stretched exponential models preferred by the largest numbers of tumours. Apparent diffusion coefficient (ADC) and diffusion coefficients from non-mono-exponential models were significantly lower in poorly differentiated tumours than well/moderately differentiated tumours. α (stretched exponential), K (kurtosis), f and D* (bi-exponential) were significantly different between tumour types. Strong correlation was observed between ADC and diffusion coefficients from other models. Non-mono-exponential models were preferred to the mono-exponential model in DW-MRI data from cervical tumours. Parameters of non-mono-exponential models showed significant differences between types and grades of tumours. (orig.)

  12. Is diffusion-weighted MRI sufficient for follow-up of neuroendocrine tumour liver metastases?

    International Nuclear Information System (INIS)

    Lavelle, L.P.; O'Neill, A.C.; McMahon, C.J.; Cantwell, C.P.; Heffernan, E.J.; Malone, D.E.; Daly, L.; Skehan, S.J.

    2016-01-01

    Aim: To assess if diffusion-weighted imaging (DWI) alone could be used for follow-up of neuroendocrine hepatic metastases. Material and methods: This was a retrospective study, approved by the institutional review board. Twenty-two patients with neuroendocrine liver metastases who had undergone more than one liver magnetic resonance imaging (MRI) examination, (including DWI and using hepatocyte-specific contrast medium) were evaluated. Up to five metastases were measured at baseline and at each subsequent examination. The reference standard measurement was performed on the hepatocyte phase by one reader. Three independent readers separately measured the same lesions on DWI sequences alone, blinded to other sequences, and recorded the presence of any new lesions. Results: The longest diameters of 317 liver metastases (91 on 22 baseline examinations and a further 226 measurements on follow-up) were measured on the reference standard by one reader and on three b-values by three other readers. The mean difference between DWI measurements and the reference standard measurement was between 0.01–0.08 cm over the nine reader/b-value combinations. Based on the width of the Bland and Altman interval containing approximately 95% of the differences between the reader observation and the mean of reference standard and DWI measurement, the narrowest interval over the nine reader/b-value combinations was −0.6 to +0.7 cm and the widest was −0.9 to 1 cm. In the evaluation of overall response using Response Evaluation Criteria in Solid Tumors (RECIST) 1.1 criteria, the weighted kappa statistic was between 0.49 and 0.86, indicating moderate-to-good agreement between the reference standard and DWI. Conclusion: The visualisation and measurement of hepatic metastases using DWI alone are within acceptable limits for clinical use, allowing the use of this rapid technique to restage hepatic disease in patients with neuroendocrine metastases. - Highlights: • DWI showed excellent

  13. Diffusion-weighted MRI of the prostate at 3.0 T: Comparison of endorectal coil (ERC) MRI and phased-array coil (PAC) MRI—The impact of SNR on ADC measurement

    International Nuclear Information System (INIS)

    Mazaheri, Yousef; Vargas, H. Alberto; Nyman, Gregory; Shukla-Dave, Amita; Akin, Oguz; Hricak, Hedvig

    2013-01-01

    Purpose: To compare ADC values measured from diffusion-weighted MR (DW-MR) images of the prostate obtained with both endorectal and phased-array coils (ERC + PAC) to those from DW-MRI images obtained with an eight-channel torso phased-array coil (PAC) at 3.0 T. Methods: The institutional review board issued a waiver of informed consent for this HIPAA-compliant study. Twenty-five patients with biopsy-proven prostate cancer underwent standard 3-T MRI using 2 different coil arrangements (ERC + PAC and PAC only) in the same session. DW-MRI at five b-values (0, 600, 1000, 1200, and 1500 s/mm 2 ) were acquired using both coil arrangements. On b = 0 images, signal-to-noise ratios (SNRs) were measured as the ratio of the mean signal from PZ and TZ ROIs to the standard deviation from the mean signal in an artifact-free ROI in the rectum. Matching regions-of-interest (ROIs) were identified in the peripheral zone and transition zone on ERC-MRI and PAC-MRI. For each ROI, mean ADC values for all zero and non-zero b-value combinations were computed. Results: Mean SNR with ERC-MRI at PZ (66.33 ± 27.07) and TZ (32.69 ± 12.52) was 9.27 and 5.52 times higher than with PAC-MRI ((7.32 ± 2.30) and (6.13 ± 1.56), respectively) (P < 0.0001 for both). ADCs from DW-MR images obtained with all b-values in the PZ and TZ were significantly lower with PAC-MRI than with ERC-MRI (P < 0.001 for all). Conclusion: Lower SNR of DW-MR images of the prostate obtained with a PAC can significantly decrease ADC values at higher b-values compared to similar measurements obtained using the ERC. To address these requirements, clinical MR systems should have image processing capabilities which incorporate the noise distribution

  14. Diffusion weighted magnetic resonance imaging: ischemic and traumatic injury of the central nervous system; Diffusionsgewichtete MRI: ischaemische und traumatische Verletzungen des Zentralnervensystems

    Energy Technology Data Exchange (ETDEWEB)

    Huisman, T.A.G.M.; Sorensen, A.G. [Massachusetts General Hospital and Harvard Medical School, Boston (United States). MGH-NMR Center; Hawighorst, H.; Benoit, C.H. [Swiss Paraplegic Center Nottwil (Switzerland). Inst. of Radiology

    2001-12-01

    Diffusion weighted magnetic resonance imaging (DWI) represents a recent development that extends imaging from the depiction of the neuroanatomy into the field of functional and physiologic processes. DWI measures a fundamentally different physiologic parameter than conventional MRI. Image contrast is related to differences in the microscopic motion (diffusion) of water molecules within brain tissue rather than a change in total tissue water. Consequently, DWI can reveal pathology where conventional T1- and T2-weighted MR images are negative. DWI has clinically proven its value in the assessment of acute cerebral stroke and trauma by showing cerebral injury early due to its ability to discriminate between lesions with cytotoxic edema (decreased diffusion) from lesions with vasogenic edema (increased diffusion). Full tensor DWI allows to calculate a variety of functional maps, the most widely used maps include maps of apparent diffusion coefficients and isotropic diffusion. In addition maps of anisotropic diffusion can be calculated which are believed to give information about the integrity and location of fiber tracts. This functional-anatomical information will most probably play an increasingly important role in the early detection of primary and secondary tissue injury from various reasons and could guide and validate current and future neuroprotective treatments. (orig.) [German] Die diffusionsgewichtete Magnetresonanz Tomografie (DWI) stellt ein neues Verfahren dar, welches die Bildgebung von der einfachen Darstellung der Neuroanatomie um das Feld der funktionalen und physiologischen Prozesse erweitert. Im Gegensatz zur konventionellen MRT misst die DWI einen vollkommen anderen physiologischen Parameter. Der Bildkontrast haengt von Unterschieden in der Mikrobewegung (Diffusion) der Wassermolekuele im Hirngewebe ab. Daher kann die DWI pathologische Prozesse aufzeichnen, wo konventionelle T1- und T2-gewichtete MR Bilder unauffaellig bleiben. In der klinischen

  15. CADrx for GBM Brain Tumors: Predicting Treatment Response from Changes in Diffusion-Weighted MRI

    Directory of Open Access Journals (Sweden)

    Matthew S. Brown

    2009-11-01

    Full Text Available The goal of this study was to develop a computer-aided therapeutic response (CADrx system for early prediction of drug treatment response for glioblastoma multiforme (GBM brain tumors with diffusion weighted (DW MR images. In conventional Macdonald assessment, tumor response is assessed nine weeks or more post-treatment. However, we will investigate the ability of DW-MRI to assess response earlier, at five weeks post treatment. The apparent diffusion coefficient (ADC map, calculated from DW images, has been shown to reveal changes in the tumor’s microenvironment preceding morphologic tumor changes. ADC values in treated brain tumors could theoretically both increase due to the cell kill (and thus reduced cell density and decrease due to inhibition of edema. In this study, we investigated the effectiveness of features that quantify changes from pre- and post-treatment tumor ADC histograms to detect treatment response. There are three parts to this study: first, tumor regions were segmented on T1w contrast enhanced images by Otsu’s thresholding method, and mapped from T1w images onto ADC images by a 3D region of interest (ROI mapping tool using DICOM header information; second, ADC histograms of the tumor region were extracted from both pre- and five weeks post-treatment scans, and fitted by a two-component Gaussian mixture model (GMM. The GMM features as well as standard histogram-based features were extracted. Finally, supervised machine learning techniques were applied for classification of responders or non-responders. The approach was evaluated with a dataset of 85 patients with GBM under chemotherapy, in which 39 responded and 46 did not, based on tumor volume reduction. We compared adaBoost, random forest and support vector machine classification algorithms, using ten-fold cross validation, resulting in the best accuracy of 69.41% and the corresponding area under the curve (Az of 0.70.

  16. Correlation of MRI apparent diffusion coefficient of invasive breast cancer with tumor tissue growth and angiogenesis

    Directory of Open Access Journals (Sweden)

    Ze-Hong Fu

    2017-08-01

    Full Text Available Objective: To study the correlation of MRI apparent diffusion coefficient (ADC value of invasive breast cancer with tumor tissue growth and angiogenesis. Methods: Patients with breast mass who were treated in Wuhan No. 6 Hospital between March 2014 and May 2017 were selected as the research subjects and divided into group A with invasive ductal carcinoma, group B with intraductal carcinoma and group C with benign lesion according to the biopsy results, magnetic resonance diffusion-weighted imaging was conducted to determine ADC values, and biopsy tissue was taken to determine the expression of proliferation genes and angiogenesis genes. Results: USP39, CyclinD1, VEGF, bFGF, Angplt-2, Angplt-3 and Angplt-4 protein expression levels in lesions of group A and group B were significantly higher than those of group C while ADC value as well as ALEX1 and Bax protein expression levels were significantly lower than those of group C; USP39, CyclinD1, VEGF, bFGF, Angplt-2, Angplt-3 and Angplt-4 protein expression levels in lesions of group A were significantly higher than those of group B while ADC value as well as ALEX1 and Bax protein expression levels was significantly lower than those of group B; USP39, CyclinD1, VEGF, bFGF, Angplt-2, Angplt-3 and Angplt-4 protein expression levels in invasive breast cancer tissue with high ADC value were significantly lower than those in invasive breast cancer tissue with low ADC value while ALEX1 and Bax protein expression levels were significantly higher than those in invasive breast cancer tissue with low ADC value. Conclusion: The decrease of ADC value of invasive breast cancer is closely related to cancer cell proliferation and angiogenesis.

  17. The use of MRI apparent diffusion coefficient (ADC) in monitoring the development of brain infarction

    International Nuclear Information System (INIS)

    Shen, Jian-Min; Xia, Xian-Wu; Kang, Wu-Gen; Yuan, Jian-Jun; Sheng, Liang

    2011-01-01

    To study the rules that apparent diffusion coefficient (ADC) changes with time and space in cerebral infarction, and to provide the evidence in defining the infarction stages. 117 work-ups in 98 patients with cerebral infarction (12 hyperacute, 43 acute, 29 subacute, 10 steady, and 23 chronic infarctions) were imaged with both conventional MRI and diffusion weighted imaging. The average ADC values, the relative ADC (rADC) values, and the ADC values or rADC values from the center to the periphery of the lesion were calculated. The average ADC values and the rADC values of hyperacute and acute infarction lesion depressed obviously. rADC values in hyperacute and acute stage was minimized, and increased progressively as time passed and appeared as 'pseudonormal' values in approximately 8 to 14 days. Thereafter, rADC values became greater than normal in chronic stage. There was positive correlation between rADC values and time (P < 0.01). The ADC values and the rADC values in hyperacute and acute lesions had gradient signs that these lesions increased from the center to the periphery. The ADC values and the rADC values in subacute lesions had adverse gradient signs that these lesions decreased from the center to the periphery. The ADC values of infarction lesions have evolution rules with time and space. The evolution rules with time and those in space can be helpful to decide the clinical stage, and to provide the evidence in guiding the treatment or judging the prognosis in infarction

  18. Metrics and textural features of MRI diffusion to improve classification of pediatric posterior fossa tumors.

    Science.gov (United States)

    Rodriguez Gutierrez, D; Awwad, A; Meijer, L; Manita, M; Jaspan, T; Dineen, R A; Grundy, R G; Auer, D P

    2014-05-01

    Qualitative radiologic MR imaging review affords limited differentiation among types of pediatric posterior fossa brain tumors and cannot detect histologic or molecular subtypes, which could help to stratify treatment. This study aimed to improve current posterior fossa discrimination of histologic tumor type by using support vector machine classifiers on quantitative MR imaging features. This retrospective study included preoperative MRI in 40 children with posterior fossa tumors (17 medulloblastomas, 16 pilocytic astrocytomas, and 7 ependymomas). Shape, histogram, and textural features were computed from contrast-enhanced T2WI and T1WI and diffusivity (ADC) maps. Combinations of features were used to train tumor-type-specific classifiers for medulloblastoma, pilocytic astrocytoma, and ependymoma types in separation and as a joint posterior fossa classifier. A tumor-subtype classifier was also produced for classic medulloblastoma. The performance of different classifiers was assessed and compared by using randomly selected subsets of training and test data. ADC histogram features (25th and 75th percentiles and skewness) yielded the best classification of tumor type (on average >95.8% of medulloblastomas, >96.9% of pilocytic astrocytomas, and >94.3% of ependymomas by using 8 training samples). The resulting joint posterior fossa classifier correctly assigned >91.4% of the posterior fossa tumors. For subtype classification, 89.4% of classic medulloblastomas were correctly classified on the basis of ADC texture features extracted from the Gray-Level Co-Occurence Matrix. Support vector machine-based classifiers using ADC histogram features yielded very good discrimination among pediatric posterior fossa tumor types, and ADC textural features show promise for further subtype discrimination. These findings suggest an added diagnostic value of quantitative feature analysis of diffusion MR imaging in pediatric neuro-oncology. © 2014 by American Journal of Neuroradiology.

  19. Diffusion-weighted magnetic resonance imaging (MRI) in acute brain stem infarction

    International Nuclear Information System (INIS)

    Narisawa, Aya; Shamoto, Hiroshi; Shimizu, Hiroaki; Tominaga, Teiji; Yoshimoto, Takashi

    2001-01-01

    Diffusion-weighted magnetic resonance imaging (DWI) provides one of the earliest demonstrations of ischemic lesions. However some lesions may be missed in the acute stage due to technical limitation of DWI. We therefore conducted the study to clarify the sensitivity of DWI to acute brain stem infarctions. Twenty-eight patients with the final diagnosis of brain stem infarction (midbrain 2, pons 9, medulla oblongata 17) who had been examined by DWI within 24 hours of onset were retrospectively analyzed for how sensitively the initial DWI demonstrated the final ischemic lesion. Only obvious (distinguishable with DWI alone without referring clinical symptoms and other informations) hyperintensity on DWI was regarded to show an ischemic lesion. Sixteen (57.1%) out of 28 patients had brain stem infarctions demonstrated by initial DWI. In the remaining 12 cases, no obvious ischemic lesion was evident on initial DWI. Subsequent MRI studies obtained 127 hours, on average after the onset showed infarction in the medulla oblongate in 11 cases and in the pons in one case. Negative findings of DWI in the acute stage does not exclude possibility of the brain stem infarction, in particularly medulla oblongata infarction. (author)

  20. Comparison of CT and diffusion-weighted MRI in acute ischemic stroke

    International Nuclear Information System (INIS)

    Moriwaki, Hiroshi; Okazaki, Shuhei; Yamada, Naoaki; Naritomi, Hiroaki

    2006-01-01

    Non-contrast CT and diffusion-weighted MRI (DWI) are widely used for assessing patients with acute ischemic stroke including candidates for thrombolytic therapy. Early CT signs, still a gold standard as the diagnostic measure for thrombolysis, are quite subtle and strongly depend on image quality. We evaluated 76 patients (47 male, mean age 71.0 yrs) with ischemic stroke of the anterior cerebral circulation who underwent CT and DWI within 6 hours of onset. The scans were examined separately by two neurologists in a blinded fashion with knowledge of the affected hemisphere. Detection of acute ischemic changes were significantly higher on DWI (72/76, 95%) compared with that on CT (50/76, 66%) (P<0.0001), especially in cases with subcortical lesions (P<0.001). Detection of the lesion with more than 33% of MCA involvement, which should exclude from the thrombolitic therapy, was somewhat higher for DWI (26/26, 100%) compared with CT (22/26, 85%). DWI is more sensitive than CT in the identification of acute ischemic stroke and can visualize major ischemia more easily than CT. Additional studies are required to determine whether these advantages of DWI are clinically relevant in the management of patients with acute stroke. (author)

  1. On conductivity, permittivity, apparent diffusion coefficient, and their usefulness as cancer markers at MRI frequencies.

    Science.gov (United States)

    Hancu, Ileana; Roberts, Jeannette Christine; Bulumulla, Selaka; Lee, Seung-Kyun

    2015-05-01

    To investigate the permittivity and conductivity of cancerous and normal tissues, their correlation to the apparent diffusion coefficient (ADC), and the specificity that they could add to cancer detection. Breast and prostate carcinomas were induced in rats. Conductivity and permittivity measurements were performed in the anesthetized animals using a dielectric probe and an impedance analyzer between 50 and 270 MHz. The correlations between ADCs (measured at 128 MHz) and conductivity values were investigated. Frequency-dependent discriminant functions were computed to assess the value that each parameter adds to cancer detection. Tumors exhibited higher permittivity than muscle tissue by 27%/12%/5% at 64/128/270MHz. Frequency independent, 15-20% higher conductivity was also noted in tumors compared to muscle tissue over the same frequency range. Strong negative correlation was observed between tissue conductivity and ADC. Whereas permittivity had the strongest discriminatory power at 64 MHz, it became comparable to ADC at 128 MHz and less important than ADC at 270 MHz. Conductivity measurements offered limited advantages in separating cancer from normal tissue beyond what ADC already provided; conversely, permittivity added separation power when added to the discriminant function. The moderately high cancerous tissue permittivity and conductivity impose strong constraints on the capability of MRI-based tissue electrical property measurements. © 2014 Wiley Periodicals, Inc.

  2. Potential of diffusion tensor MRI in the assessment of periventricular leukomalacia

    International Nuclear Information System (INIS)

    Fan, G.G.; Yu, B.; Quan, S.M.; Sun, B.H.; Guo, Q.Y.

    2006-01-01

    AIM: To investigate magnetic resonance (MR) diffusion tensor imaging (DTI) and fibre tractography in the assessment of altered major white matter (WM) fibre tracts in periventricular leukomalacia (PVL). MATERIALS AND METHODS: Twelve children (male:female=7:5, age range 3-10 years; mean age=6.5 years) who had suffered PVL were included in this study. Meanwhile, Twelve age-matched normal controls (male:female=6:6, age range 4-12 years; mean age=7.3 years) with normal MRI findings and no neurological abnormalities were recruited for comparison. DTI was performed with 15 different diffusion gradient directions and DTI colour maps were created from fractional anisotropy (FA) values and the three vector elements. To identify alteration of WM fibre tracts in patient of PVL quantitatively, FA values on diffusion tensor colour maps were compared between the patients and controls. Quantitative analysis was performed using the regions of interest (ROI) method settled on the central part of all identifiable WM fibres, including the corticospinal tract (CST) in the brainstem, middle cerebellar peduncle (MCP), medial lemniscus (ML), anterior/posterior limb of internal capsule (ICAL/ICPL), arcuate fasciculus (AF), posterior thalamic radiation (PTR), genu of corpus callosum (GCC), splenium of corpus callosum (SCC), corona radiata (CR), cingulum (CG), and superior longitudinal fasciculus (SLF). The averaged FA value of each WM fibre was measured and summarized as the mean±standard deviation (SD). All data were analysed by paired Student's t-test. A p-value of less than 0.05 was considered to indicate statistical significance. RESULTS: Visual investigation of WM fibre tracts showed that the ICAL, brainstem CST, ML, MCP, and external capsule (EC) was similar in controls and subjects. However, the ICPL, AF, PTR, CR, CG, SLF and corpus callosum, were all attenuated in size. All 12 cases of PVL showed a significant mean FA reduction in the ICPL, AF, PTR, CR, CG, SLF, SCC, and GCC in

  3. MRI and unilateral NMR study of reindeer skin tanning processes.

    Science.gov (United States)

    Zhu, Lizheng; Del Federico, Eleonora; Ilott, Andrew J; Klokkernes, Torunn; Kehlet, Cindie; Jerschow, Alexej

    2015-04-07

    The study of arctic or subarctic indigenous skin clothing material, known for its design and ability to keep the body warm, provides information about the tanning materials and techniques. The study also provides clues about the culture that created it, since tanning processes are often specific to certain indigenous groups. Untreated skin samples and samples treated with willow (Salix sp) bark extract and cod liver oil are compared in this study using both MRI and unilateral NMR techniques. The two types of samples show different proton spatial distributions and different relaxation times, which may also provide information about the tanning technique and aging behavior.

  4. Conventional 3T brain MRI and diffusion tensor imaging in the diagnostic workup of early stage parkinsonism

    International Nuclear Information System (INIS)

    Meijer, Frederick J.A.; Rumund, Anouke van; Tuladhar, Anil M.; Aerts, Marjolein B.; Titulaer, Imke; Esselink, Rianne A.J.; Bloem, Bastiaan R.; Verbeek, Marcel M.; Goraj, Bozena

    2015-01-01

    The aim of this study is to evaluate whether the diagnostic accuracy of 3 T brain MRI is improved by region of interest (ROI) measures of diffusion tensor imaging (DTI), to differentiate between neurodegenerative atypical parkinsonism (AP) and Parkinson's disease (PD) in early stage parkinsonism. We performed a prospective observational cohort study of 60 patients presenting with early stage parkinsonism and initial uncertain diagnosis. At baseline, patients underwent a 3 T brain MRI including DTI. After clinical follow-up (mean 28.3 months), diagnoses could be made in 49 patients (30 PD and 19 AP). Conventional brain MRI was evaluated for regions of atrophy and signal intensity changes. Tract-based spatial statistics and ROI analyses of DTI were performed to analyze group differences in mean diffusivity (MD) and fractional anisotropy (FA), and diagnostic thresholds were determined. Diagnostic accuracy of conventional brain MRI and DTI was assessed with the receiver operating characteristic (ROC). Significantly higher MD of the centrum semiovale, body corpus callosum, putamen, external capsule, midbrain, superior cerebellum, and superior cerebellar peduncles was found in AP. Significantly increased MD of the putamen was found in multiple system atrophy-parkinsonian form (MSA-P) and increased MD in the midbrain and superior cerebellar peduncles in progressive supranuclear palsy (PSP). The diagnostic accuracy of brain MRI to identify AP as a group was not improved by ROI measures of MD, though the diagnostic accuracy to identify MSA-P was slightly increased (AUC 0.82 to 0.85). The diagnostic accuracy of brain MRI to identify AP as a group was not improved by the current analysis approach to DTI, though DTI measures could be of added value to identify AP subgroups. (orig.)

  5. MRI-only lesions: application of diffusion-weighted imaging obviates unnecessary MR-guided breast biopsies

    Energy Technology Data Exchange (ETDEWEB)

    Spick, Claudio; Pinker-Domenig, Katja; Helbich, Thomas H.; Baltzer, Pascal A. [Medical University of Vienna (AKH), General Hospital Vienna, Department of Biomedical Imaging and Image-guided Therapy, Division of Molecular and Gender Imaging, Wien (Austria); Rudas, Margaretha [Medical University of Vienna (AKH), Clinical Institute of Pathology, Wien (Austria)

    2014-06-15

    To assess if the application of diffusion-weighted imaging (DWI) obviates unnecessary MR-guided biopsies in suspicious breast lesions visible only on contrast-enhanced MRI (CE-MRI). This institutional review board (IRB)-approved, retrospective, single-centre study included 101 patients (mean age, 49.5; SD 13.9 years) who underwent additional DWI at 1.5 T prior to MRI-guided biopsy of 104 lesions classified as suspicious for malignancy and visible on CE-MRI only. An experienced radiologist, blinded to histopathologic and follow-up results, measured apparent diffusion coefficient (ADC) values obtained from DWI. Diagnostic accuracy was investigated using receiver operating characteristics (ROC) analysis. Histopathology revealed 20 malignant and 84 benign lesions. Lesions were masses in 61 (15 malignant, 24.6 %) and non-masses in 43 cases (five malignant, 11.6 %). Mean ADC values were 1.53 ± 0.38 x 10{sup -3} mm{sup 2}/s in benign lesions and 1.06 ± 0.27 x 10{sup -3} mm{sup 2}/s in malignant lesions. ROC analysis revealed exclusively benign lesions if ADC values were greater than 1.58 x 10{sup -3} mm{sup 2}/s. As a consequence, 29 false-positive biopsies (34.5 %) could have been avoided without any false-negative findings. Both in mass and in non-mass lesions, rule-in and rule-out criteria were identified using flexible ADC thresholds based on ROC analysis. Additional application of DWI in breast lesions visible only on MRI can avoid false-positive, MR-guided biopsies. Thus, DWI should be an integral part of breast MRI protocols. (orig.)

  6. Conventional 3T brain MRI and diffusion tensor imaging in the diagnostic workup of early stage parkinsonism

    Energy Technology Data Exchange (ETDEWEB)

    Meijer, Frederick J.A. [Radboud University Nijmegen Medical Center, Department of Radiology and Nuclear Medicine, Nijmegen (Netherlands); Rumund, Anouke van; Tuladhar, Anil M.; Aerts, Marjolein B.; Titulaer, Imke; Esselink, Rianne A.J.; Bloem, Bastiaan R. [Radboud University Nijmegen Medical Center, Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Nijmegen (Netherlands); Verbeek, Marcel M. [Radboud University Nijmegen Medical Center, Department of Neurology, Donders Institute for Brain, Cognition and Behaviour, Nijmegen (Netherlands); Radboud University Nijmegen Medical Center, Department of Laboratory Medicine, Nijmegen (Netherlands); Goraj, Bozena [Radboud University Nijmegen Medical Center, Department of Radiology and Nuclear Medicine, Nijmegen (Netherlands); Medical Center of Postgraduate Education, Department of Diagnostic Imaging, Warsaw (Poland)

    2015-07-15

    The aim of this study is to evaluate whether the diagnostic accuracy of 3 T brain MRI is improved by region of interest (ROI) measures of diffusion tensor imaging (DTI), to differentiate between neurodegenerative atypical parkinsonism (AP) and Parkinson's disease (PD) in early stage parkinsonism. We performed a prospective observational cohort study of 60 patients presenting with early stage parkinsonism and initial uncertain diagnosis. At baseline, patients underwent a 3 T brain MRI including DTI. After clinical follow-up (mean 28.3 months), diagnoses could be made in 49 patients (30 PD and 19 AP). Conventional brain MRI was evaluated for regions of atrophy and signal intensity changes. Tract-based spatial statistics and ROI analyses of DTI were performed to analyze group differences in mean diffusivity (MD) and fractional anisotropy (FA), and diagnostic thresholds were determined. Diagnostic accuracy of conventional brain MRI and DTI was assessed with the receiver operating characteristic (ROC). Significantly higher MD of the centrum semiovale, body corpus callosum, putamen, external capsule, midbrain, superior cerebellum, and superior cerebellar peduncles was found in AP. Significantly increased MD of the putamen was found in multiple system atrophy-parkinsonian form (MSA-P) and increased MD in the midbrain and superior cerebellar peduncles in progressive supranuclear palsy (PSP). The diagnostic accuracy of brain MRI to identify AP as a group was not improved by ROI measures of MD, though the diagnostic accuracy to identify MSA-P was slightly increased (AUC 0.82 to 0.85). The diagnostic accuracy of brain MRI to identify AP as a group was not improved by the current analysis approach to DTI, though DTI measures could be of added value to identify AP subgroups. (orig.)

  7. Role of diffusion-weighted MRI in differentiation of hepatic abscesses from non-infected fluid collections.

    Science.gov (United States)

    Schmid-Tannwald, C; Schmid-Tannwald, C M; Morelli, J N; Neumann, R; Reiser, M F; Nikolaou, K; Rist, C

    2014-07-01

    To evaluate the role of diffusion-weighted magnetic resonance imaging (DW-MRI) in the differentiation of hepatic abscesses from non-infected fluid collections. In this retrospective study, 22 hepatic abscesses and 27 non-infected hepatic fluid collections were examined in 27 patients who underwent abdominal MRI including DW-MRI. Two independent observers reviewed T2-weighted + DW-MRI and T2-weighted + contrast-enhanced T1-weighted (CET1W) images in two sessions. Detection rates and confidence levels were calculated and compared using McNemar's and Wilcoxon's signed rank tests, respectively. Apparent diffusion coefficient (ADC) values of abscesses and non-infected fluid collections were compared using the t-test. Receiver operating characteristic (ROC) curves were constructed. There was no statistically significant difference in the accuracy of detecting abscesses using T2-weighted + DW-MRI (both observers: 21/22, 95.5%) versus T2-weighted + CET1W images (observer 1: 21/22, 95.5%; observer 2: 22/22, 100%; p collections (0.83 ± 0.24 versus 2.25 ± 0.61 × 10(-3) mm(2)/s; p collections at a threshold ADC value of 1.36 × 10(-3) mm(2)/s. DW-MRI allows qualitative and quantitative differentiation of abscesses from non-infected fluid collections in the liver. Copyright © 2014 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

  8. Diffusion- and Perfusion-weighted MRI Studies Just Before and After Removal of Hypertensive Putaminal Hematoma: Case Report

    OpenAIRE

    木下, 良正; 安河内, 秀興; 原田, 篤邦; 津留, 英智; 奥寺, 利男; 横田, 晃; Yoshimasa, KINOSHITA; Hideoki, YASUKOUCHI; Atsukuni, HARADA; Eichi, TSURU; Toshio, OKUDERA; Akira, YOKOTA; 宗像水光会総合病院 脳神経外科; 宗像水光会総合病院 脳神経外科; 宗像水光会総合病院 脳神経外科

    2007-01-01

    It has been suspected that a zone of perihematomal ischemia analogous to an ischemic penumbra exists in patients with subacute putaminal hemorrhage who showed transient neurological improvement with hyperbaric oxygenation therapy (HBO). A 54-year-old woman, who suffered from left putaminal hemorrhage, was examined for regional hemodynamics in the perihematomal region just before and just after the removal of putaminal hematoma in the subacute period by diffusion and perfusion MRI. The pyramid...

  9. Choosing the polarity of the phase-encoding direction in diffusion MRI: Does it matter for group analysis?

    OpenAIRE

    Kennis, M.; van Rooij, S.J.H.; Kahn, R.S.; Geuze, E.; Leemans, A.

    2016-01-01

    Notorious for degrading diffusion MRI data quality are so-called susceptibility-induced off-resonance fields, which cause non-linear geometric image deformations. While acquiring additional data to correct for these distortions alleviates the adverse effects of this artifact drastically – e.g., by reversing the polarity of the phase-encoding (PE) direction – this strategy is often not an option due to scan time constraints. Especially in a clinical context, where patient comfort and safety ar...

  10. Telomere length and advanced diffusion MRI as biomarkers for repetitive mild traumatic brain injury in adolescent rats

    Directory of Open Access Journals (Sweden)

    David K. Wright

    Full Text Available Mild traumatic brain injuries (mTBI are of worldwide concern in adolescents of both sexes, and repeated mTBI (RmTBI may have serious long-term neurological consequences. As such, the study of RmTBI and discovery of objective biomarkers that can help guide medical decisions is an important undertaking. Diffusion-weighted MRI (DWI, which provides markers of axonal injury, and telomere length (TL are two clinically relevant biomarkers that have been implicated in a number of neurological conditions, and may also be affected by RmTBI. Therefore, this study utilized the lateral impact injury model of RmTBI to investigate changes in diffusion MRI and TL, and how these changes relate to each other. Adolescent male and female rats received either three mTBIs or three sham injuries. The first injury was given on postnatal day 30 (P30, with the repeated injuries separated by four days each. Seven days after the final injury, a sample of ear tissue was collected for TL analysis. Rats were then euthanized and whole brains were collected and fixated for MRI analyses that included diffusion and high-resolution structural sequences. Compared to the sham-injured group, RmTBI rats had significantly shorter TL at seven days post-injury. Analysis of advanced DWI measures found that RmTBI rats had abnormalities in the corpus callosum and cortex at seven days post-injury. Notably, many of the DWI changes were correlated with TL. These findings demonstrate that TL and DWI measurements are changed by RmTBI and may represent clinically applicable biomarkers for this. Keywords: Biomarker, Concussion, Track weighted imaging, Animal model, Diffusion tensor imaging, MRI

  11. MRI

    DEFF Research Database (Denmark)

    Schroeter, Aileen; Rudin, Markus; Gianolio, Eliana

    2017-01-01

    This chapter discusses principles of nuclear magnetic resonance (NMR) and MRI followed by a survey on the major classes of MRI contrast agents (CA), their modes of action, and some of the most significative applications. The two more established classes of MRI-CA are represented by paramagnetic...... been attained that markedly increase the number and typology of systems with CEST properties. Currently much attention is also devoted to hyperpolarized molecules that display a sensitivity enhancement sufficient for their direct exploitation for the formation of the MR image. A real breakthrough...

  12. Contribution of the diffusion-weighted MRI in the diagnosis and follow-up of encephalopathy caused by maple syrup urine disease in a full-term newborn

    International Nuclear Information System (INIS)

    Ferraz-Filho, Jose Roberto Lopes; Floriano, Valdeci Helio; Quirici, Marcelo Bianco; Souza, Antonio Soares; Albuquerque, Regina Pires de

    2009-01-01

    The purpose of this case report is to show conventional MRI and diffusion-weighted imaging (DWI) findings of the different evolutionary phases in MSUD (Maple syrup urine disease) of a newborn that evolved with brain white matter lesions (author)

  13. MRI

    Science.gov (United States)

    ... the room. Pins, hairpins, metal zippers, and similar metallic items can distort the images. Removable dental work ... an MRI can cause heart pacemakers and other implants not to work as well. The magnets can ...

  14. Neurite density imaging versus imaging of microscopic anisotropy in diffusion MRI: A model comparison using spherical tensor encoding.

    Science.gov (United States)

    Lampinen, Björn; Szczepankiewicz, Filip; Mårtensson, Johan; van Westen, Danielle; Sundgren, Pia C; Nilsson, Markus

    2017-02-15

    In diffusion MRI (dMRI), microscopic diffusion anisotropy can be obscured by orientation dispersion. Separation of these properties is of high importance, since it could allow dMRI to non-invasively probe elongated structures such as neurites (axons and dendrites). However, conventional dMRI, based on single diffusion encoding (SDE), entangles microscopic anisotropy and orientation dispersion with intra-voxel variance in isotropic diffusivity. SDE-based methods for estimating microscopic anisotropy, such as the neurite orientation dispersion and density imaging (NODDI) method, must thus rely on model assumptions to disentangle these features. An alternative approach is to directly quantify microscopic anisotropy by the use of variable shape of the b-tensor. Along those lines, we here present the 'constrained diffusional variance decomposition' (CODIVIDE) method, which jointly analyzes data acquired with diffusion encoding applied in a single direction at a time (linear tensor encoding, LTE) and in all directions (spherical tensor encoding, STE). We then contrast the two approaches by comparing neurite density estimated using NODDI with microscopic anisotropy estimated using CODIVIDE. Data were acquired in healthy volunteers and in glioma patients. NODDI and CODIVIDE differed the most in gray matter and in gliomas, where NODDI detected a neurite fraction higher than expected from the level of microscopic diffusion anisotropy found with CODIVIDE. The discrepancies could be explained by the NODDI tortuosity assumption, which enforces a connection between the neurite density and the mean diffusivity of tissue. Our results suggest that this assumption is invalid, which leads to a NODDI neurite density that is inconsistent between LTE and STE data. Using simulations, we demonstrate that the NODDI assumptions result in parameter bias that precludes the use of NODDI to map neurite density. With CODIVIDE, we found high levels of microscopic anisotropy in white matter

  15. Temporal comparison of functional brain imaging with diffuse optical tomography and fMRI during rat forepaw stimulation

    International Nuclear Information System (INIS)

    Siegel, Andrew M; Culver, Joseph P; Mandeville, Joseph B; Boas, David A

    2003-01-01

    The time courses of oxyhaemoglobin ([HbO 2 ]), deoxyhaemoglobin ([HbR]) and total haemoglobin ([HbT]) concentration changes following cortical activation in rats by electrical forepaw stimulation were measured using diffuse optical tomography (DOT) and compared to similar measurements performed previously with fMRI at 2.0 T and 4.7 T. We also explored the qualitative effects of varying stimulus parameters on the temporal evolution of the hemodynamic response. DOT images were reconstructed at a depth of 1.5 mm over a 1 cm square area from 2 mm anterior to bregma to 8 mm posterior to bregma. The measurement set included 9 sources and 16 detectors with an imaging frame rate of 10 Hz. Both DOT [HbR] and [HbO 2 ] time courses were compared to the fMRI BOLD time course during stimulation, and the DOT [HbT] time course was compared to the fMRI cerebral plasma volume (CPV) time course. We believe that DOT and fMRI can provide similar temporal information for both blood volume and deoxyhaemoglobin changes, which helps to cross-validate these two techniques and to demonstrate that DOT can be useful as a complementary modality to fMRI for investigating the hemodynamic response to neuronal activity

  16. Liver Imaging Reporting and Data System on CT and gadoxetic acid-enhanced MRI with diffusion-weighted imaging

    Energy Technology Data Exchange (ETDEWEB)

    Cha, Dong Ik; Jang, Kyung Mi; Kim, Seong Hyun; Kang, Tae Wook; Song, Kyoung Doo [Sungkyunkwan University School of Medicine, Department of Radiology and Center for Imaging Science, Samsung Medical Center, Seoul (Korea, Republic of)

    2017-10-15

    To assess major imaging features of Liver Imaging Reporting and Data System (LI-RADS) on contrast-enhanced CT and gadoxetic acid-enhanced MRI and to estimate whether the combination of signal intensity favouring HCC on hepatobiliary phase (HBP) and diffusion-weighted images (DWI) can act as a major feature in LI-RADS. Four hundred twenty one patients with 445 observations were included. Major features of LI-RADS on CT and MRI as well as HBP and DWI features were assessed. Diagnostic performances of LR-5 according to LI-RADS v2014 and modified LI-RADS which incorporate combination of HBP and DWI were assessed. Pairwise comparisons of the receiver operating characteristic (ROC) curves were performed. For HCCs, capsule appearance had the highest rate of discordance between CT and MRI (32.7%), followed by washout appearance (22.2%). Specificity (75%) of LR-5 of LI-RADS v2014 was lower than that (77.1-79.2%) of modified LI-RADS. Area under the ROC curve of modified LI-RADS (0.755-0.775) was not significantly different from that of LI-RADS v 2014 (0.709) (p > 0.05). There were substantial discordances between CT and MRI for capsule and washout appearances in hepatic observations, and combination of gadoxetic acid-enhanced MRI and DWI might be able to be incorporated as a major feature of LI-RADS. (orig.)

  17. Temporal comparison of functional brain imaging with diffuse optical tomography and fMRI during rat forepaw stimulation

    Energy Technology Data Exchange (ETDEWEB)

    Siegel, Andrew M [Tufts University Bioengineering Center, Medford, MA 02155 (United States); Culver, Joseph P [Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02129 (United States); Mandeville, Joseph B [Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02129 (United States); Boas, David A [Martinos Center for Biomedical Imaging, Massachusetts General Hospital, Harvard Medical School, Boston, MA 02129 (United States)

    2003-05-21

    The time courses of oxyhaemoglobin ([HbO{sub 2}]), deoxyhaemoglobin ([HbR]) and total haemoglobin ([HbT]) concentration changes following cortical activation in rats by electrical forepaw stimulation were measured using diffuse optical tomography (DOT) and compared to similar measurements performed previously with fMRI at 2.0 T and 4.7 T. We also explored the qualitative effects of varying stimulus parameters on the temporal evolution of the hemodynamic response. DOT images were reconstructed at a depth of 1.5 mm over a 1 cm square area from 2 mm anterior to bregma to 8 mm posterior to bregma. The measurement set included 9 sources and 16 detectors with an imaging frame rate of 10 Hz. Both DOT [HbR] and [HbO{sub 2}] time courses were compared to the fMRI BOLD time course during stimulation, and the DOT [HbT] time course was compared to the fMRI cerebral plasma volume (CPV) time course. We believe that DOT and fMRI can provide similar temporal information for both blood volume and deoxyhaemoglobin changes, which helps to cross-validate these two techniques and to demonstrate that DOT can be useful as a complementary modality to fMRI for investigating the hemodynamic response to neuronal activity.

  18. Comparison of gadolinium-EOB-DTPA-enhanced and diffusion-weighted liver MRI for detection of small hepatic metastases.

    Science.gov (United States)

    Shimada, Kotaro; Isoda, Hiroyoshi; Hirokawa, Yuusuke; Arizono, Shigeki; Shibata, Toshiya; Togashi, Kaori

    2010-11-01

    To compare the accuracy of gadolinium ethoxybenzyl-diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced MRI with that of diffusion-weighted MRI (DWI) in the detection of small hepatic metastases (2 cm or smaller). Forty-five patients underwent abdominal MRI at 3 T, including T1-weighted imaging (T1WI), T2-weighted imaging (T2WI), heavily T2WI (HASTE), DWI with a b-value of 500 s/mm(2) and contrast-enhanced MRI with Gd-EOB-DTPA. Two groups were assigned and compared: group A (T1WI, T2WI, HASTE and contrast-enhanced study with Gd-EOB-DTPA), and group B (T1WI, T2WI, HASTE and DWI). Two observers independently interpreted the images obtained in a random order. For all hepatic metastases, the diagnostic performance using each imaging set was evaluated by receiver-operating characteristic (ROC) curve analysis. A total of 51 hepatic metastases were confirmed. The area under the ROC curve (Az) of group A was larger than that of group B, and the difference in the mean Az values between the two image sets was statistically significant, whereas, there were three metastases that lay near thin vessels or among multiple cysts and were better visualised in group B than in group A. Gd-EOB-DTPA-enhanced MRI showed higher accuracy in the detection of small metastases than DWI.

  19. Transient ischemic attacks and presence of an acute brain lesion in diffusion-weighted MRI: study of 50 patients

    Directory of Open Access Journals (Sweden)

    Sabeti M

    2012-10-01

    Full Text Available Background: Finding an acute brain lesion by diffusion-weighted (DW MRI upon an episode of transient ischemic attack (TIA is a predictor of imminent stroke in the near future. Therefore, exploring risk factors associated with lesions in DW-MRI of the brain is important in adopting an approach to TIA management. In the current study, we tried to determine the risk factors associated with lesions in DW-MRI of the brain in patients experiencing TIA episodes.Methods: Fifty patients with TIA were recruited consecutively in Sina Hospital, Tehran, Iran, over a 6-month period between July 2008 and January 2009. All of the patients underwent a complete neurological examination and laboratory tests. Brain DW-MRIs were performed for all the patients within 72 hours of a TIA episode.Results: DW-MRI revealed an acute lesion in 16% of the participants. There was a significant correlation between presence of an acute lesion in DW-MRI and TIA duration, history of diabetes mellitus and presence of unilateral facial palsy (P=0.0003, P=0.02 and P=0.008, respectively. Other variables such as age, hypertension, hyperlipidemia, past history of TIA, headache, vertigo, and sensory or visual disturbances had no significant relation with the presence of an acute lesion in DW-MRI.Conclusion: Duration of TIA, presence of diabetes mellitus and unilateral facial palsy are risk factors for an acute lesion in DW-MRI, meaning that patients with such risk factors are at risk for stroke in the near future.

  20. Analysis of the utility of diffusion-weighted MRI and apparent diffusion coefficient values in distinguishing central nervous system toxoplasmosis from lymphoma

    International Nuclear Information System (INIS)

    Schroeder, Paul C.; Donovan Post, M. Judith; Bruce-Gregorios, Jocelyn; Oschatz, Elizabeth; Stadler, Alfred; Thurnher, Majda M.

    2006-01-01

    Toxoplasmosis and lymphoma are common lesions of the central nervous system in patients with AIDS. It is often difficult to distinguish between these lesions both clinically and radiographically. Previous research has demonstrated restricted diffusion within cerebral lymphomas and bacterial abscesses. However, little work has been done to evaluate the diffusion characteristics of toxoplasmosis lesions. This study was designed to explore further the utility of diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) maps and values in making the distinction between toxoplasmosis and lymphoma. The magnetic resonance imaging (MRI) studies of 36 patients, including 22 with toxoplasmosis (all of whom had AIDS) and 14 with lymphoma (8 of whom had AIDS), at two institutions were reviewed retrospectively. The characteristics of the lesions on DWI were evaluated, and the ADC ratios of the lesions were calculated and compared. There was significant overlap of the ADC ratios of toxoplasma and lymphoma, most notably in the intermediate (1.0-1.6) range. There was variability in ADC ratios even among different lesions in the same patient. In only a minority of the lymphoma patients were the ADC ratios low enough to suggest the correct diagnosis. Our study showed that toxoplasmosis exhibits a wide spectrum of diffusion characteristics with ADC ratios which have significant overlap with those of lymphoma. Therefore, in the majority of patients, ADC ratios are not definitive in making the distinction between toxoplasmosis and lymphoma. (orig.)

  1. Analysis of the utility of diffusion-weighted MRI and apparent diffusion coefficient values in distinguishing central nervous system toxoplasmosis from lymphoma

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, Paul C.; Donovan Post, M. Judith; Bruce-Gregorios, Jocelyn [University of Miami, Jackson Memorial Hospital, Miami, FL (United States); Oschatz, Elizabeth; Stadler, Alfred; Thurnher, Majda M. [Medical University of Vienna, Department of Radiology Neuroradiology Section, Vienna (Austria)

    2006-10-15

    Toxoplasmosis and lymphoma are common lesions of the central nervous system in patients with AIDS. It is often difficult to distinguish between these lesions both clinically and radiographically. Previous research has demonstrated restricted diffusion within cerebral lymphomas and bacterial abscesses. However, little work has been done to evaluate the diffusion characteristics of toxoplasmosis lesions. This study was designed to explore further the utility of diffusion-weighted imaging (DWI) and apparent diffusion coefficient (ADC) maps and values in making the distinction between toxoplasmosis and lymphoma. The magnetic resonance imaging (MRI) studies of 36 patients, including 22 with toxoplasmosis (all of whom had AIDS) and 14 with lymphoma (8 of whom had AIDS), at two institutions were reviewed retrospectively. The characteristics of the lesions on DWI were evaluated, and the ADC ratios of the lesions were calculated and compared. There was significant overlap of the ADC ratios of toxoplasma and lymphoma, most notably in the intermediate (1.0-1.6) range. There was variability in ADC ratios even among different lesions in the same patient. In only a minority of the lymphoma patients were the ADC ratios low enough to suggest the correct diagnosis. Our study showed that toxoplasmosis exhibits a wide spectrum of diffusion characteristics with ADC ratios which have significant overlap with those of lymphoma. Therefore, in the majority of patients, ADC ratios are not definitive in making the distinction between toxoplasmosis and lymphoma. (orig.)

  2. Readout-segmented multi-shot diffusion-weighted MRI of the knee joint in patients with juvenile idiopathic arthritis.

    Science.gov (United States)

    Sauer, Alexander; Li, Mengxia; Holl-Wieden, Annette; Pabst, Thomas; Neubauer, Henning

    2017-10-12

    Diffusion-weighted MRI has been proposed as a new technique for imaging synovitis without intravenous contrast application. We investigated diagnostic utility of multi-shot readout-segmented diffusion-weighted MRI (multi-shot DWI) for synovial imaging of the knee joint in patients with juvenile idiopathic arthritis (JIA). Thirty-two consecutive patients with confirmed or suspected JIA (21 girls, median age 13 years) underwent routine 1.5 T MRI with contrast-enhanced T1w imaging (contrast-enhanced MRI) and with multi-shot DWI (RESOLVE, b-values 0-50 and 800 s/mm 2 ). Contrast-enhanced MRI, representing the diagnostic standard, and diffusion-weighted images at b = 800 s/mm 2 were separately rated by three independent blinded readers at different levels of expertise for the presence and the degree of synovitis on a modified 5-item Likert scale along with the level of subjective diagnostic confidence. Fourteen (44%) patients had active synovitis and joint effusion, nine (28%) patients showed mild synovial enhancement not qualifying for arthritis and another nine (28%) patients had no synovial signal alterations on contrast-enhanced imaging. Ratings by the 1st reader on contrast-enhanced MRI and on DWI showed substantial agreement (κ = 0.74). Inter-observer-agreement was high for diagnosing, or ruling out, active arthritis of the knee joint on contrast-enhanced MRI and on DWI, showing full agreement between 1st and 2nd reader and disagreement in one case (3%) between 1st and 3rd reader. In contrast, ratings in cases of absent vs. little synovial inflammation were markedly inconsistent on DWI. Diagnostic confidence was lower on DWI, compared to contrast-enhanced imaging. Multi-shot DWI of the knee joint is feasible in routine imaging and reliably diagnoses, or rules out, active arthritis of the knee joint in paediatric patients without the need of gadolinium-based i.v. contrast injection. Possibly due to "T2w shine-through" artifacts, DWI does not reliably

  3. Value of conventional, and diffusion- and perfusion weighted MRI in the management of patients with unclear cerebral pathology, admitted to the intensive care unit

    International Nuclear Information System (INIS)

    Sundgren, P.C.; Reinstrup, P.; Romner, B.; Holtaas, S.; Maly, P.

    2002-01-01

    The aim of our retrospective study was to determine the extent to which diffusion- and perfusion- weighted MRI combined with conventional MRI could be helpful in the evaluation of intensive care unit (ICU) patients who have unknown or unclear cerebral pathology underlying a serious clinical condition. Twenty-one ICU patients with disparity between the findings on brain CT scan and their clinical status were studied. All patients underwent conventional MR and diffusion-weighted imaging and 14 also had MR perfusion studies. Abnormalities were present on diffusion-weighted imaging of 17 of the 21 patients and on perfusion-weighted studies of 7 of 14 patients. The MRI results changed the preliminary/working diagnosis in six patients. In eight other patients, MRI revealed additional pathology that had not been suspected clinically, and/or characterized more closely findings that had already been detected by CT or suspected clinically. MRI showed abnormalities in four of the five patients who had normal CT. MRI findings suggested a negative clinical outcome in all nine patients who subsequently died. MRI findings also suggested positive long-term outcome in five of nine patients who improved significantly as based on Glasgow and extended Glasgow outcome scales. In the three unconscious patients who had normal diffusion- and perfusion-weighted imaging the clinical outcome was good. This study suggests that MRI in seriously ill ICU patients with unclear cerebral pathology can provide information that changes, characterizes, or supports diagnoses and/or prognoses and therefore facilitates further management. (orig.)

  4. Feynman-Kac equations for reaction and diffusion processes

    Science.gov (United States)

    Hou, Ru; Deng, Weihua

    2018-04-01

    This paper provides a theoretical framework for deriving the forward and backward Feynman-Kac equations for the distribution of functionals of the path of a particle undergoing both diffusion and reaction processes. Once given the diffusion type and reaction rate, a specific forward or backward Feynman-Kac equation can be obtained. The results in this paper include those for normal/anomalous diffusions and reactions with linear/nonlinear rates. Using the derived equations, we apply our findings to compute some physical (experimentally measurable) statistics, including the occupation time in half-space, the first passage time, and the occupation time in half-interval with an absorbing or reflecting boundary, for the physical system with anomalous diffusion and spontaneous evanescence.

  5. Simple computation of reaction–diffusion processes on point clouds

    KAUST Repository

    Macdonald, Colin B.; Merriman, Barry; Ruuth, Steven J.

    2013-01-01

    The study of reaction-diffusion processes is much more complicated on general curved surfaces than on standard Cartesian coordinate spaces. Here we show how to formulate and solve systems of reaction-diffusion equations on surfaces in an extremely simple way, using only the standard Cartesian form of differential operators, and a discrete unorganized point set to represent the surface. Our method decouples surface geometry from the underlying differential operators. As a consequence, it becomes possible to formulate and solve rather general reaction-diffusion equations on general surfaces without having to consider the complexities of differential geometry or sophisticated numerical analysis. To illustrate the generality of the method, computations for surface diffusion, pattern formation, excitable media, and bulk-surface coupling are provided for a variety of complex point cloud surfaces.

  6. Simple computation of reaction–diffusion processes on point clouds

    KAUST Repository

    Macdonald, Colin B.

    2013-05-20

    The study of reaction-diffusion processes is much more complicated on general curved surfaces than on standard Cartesian coordinate spaces. Here we show how to formulate and solve systems of reaction-diffusion equations on surfaces in an extremely simple way, using only the standard Cartesian form of differential operators, and a discrete unorganized point set to represent the surface. Our method decouples surface geometry from the underlying differential operators. As a consequence, it becomes possible to formulate and solve rather general reaction-diffusion equations on general surfaces without having to consider the complexities of differential geometry or sophisticated numerical analysis. To illustrate the generality of the method, computations for surface diffusion, pattern formation, excitable media, and bulk-surface coupling are provided for a variety of complex point cloud surfaces.

  7. Markov Jump Processes Approximating a Non-Symmetric Generalized Diffusion

    International Nuclear Information System (INIS)

    Limić, Nedžad

    2011-01-01

    Consider a non-symmetric generalized diffusion X(⋅) in ℝ d determined by the differential operator A(x) = -Σ ij ∂ i a ij (x)∂ j + Σ i b i (x)∂ i . In this paper the diffusion process is approximated by Markov jump processes X n (⋅), in homogeneous and isotropic grids G n ⊂ℝ d , which converge in distribution in the Skorokhod space D([0,∞),ℝ d ) to the diffusion X(⋅). The generators of X n (⋅) are constructed explicitly. Due to the homogeneity and isotropy of grids, the proposed method for d≥3 can be applied to processes for which the diffusion tensor {a ij (x)} 11 dd fulfills an additional condition. The proposed construction offers a simple method for simulation of sample paths of non-symmetric generalized diffusion. Simulations are carried out in terms of jump processes X n (⋅). For piece-wise constant functions a ij on ℝ d and piece-wise continuous functions a ij on ℝ 2 the construction and principal algorithm are described enabling an easy implementation into a computer code.

  8. Nonergodicity, fluctuations, and criticality in heterogeneous diffusion processes.

    Science.gov (United States)

    Cherstvy, A G; Metzler, R

    2014-07-01

    We study the stochastic behavior of heterogeneous diffusion processes with the power-law dependence D(x) ∼ |x|(α) of the generalized diffusion coefficient encompassing sub- and superdiffusive anomalous diffusion. Based on statistical measures such as the amplitude scatter of the time-averaged mean-squared displacement of individual realizations, the ergodicity breaking and non-Gaussianity parameters, as well as the probability density function P(x,t), we analyze the weakly nonergodic character of the heterogeneous diffusion process and, particularly, the degree of irreproducibility of individual realizations. As we show, the fluctuations between individual realizations increase with growing modulus |α| of the scaling exponent. The fluctuations appear to diverge when the critical value α = 2 is approached, while for even larger α the fluctuations decrease, again. At criticality, the power-law behavior of the mean-squared displacement changes to an exponentially fast growth, and the fluctuations of the time-averaged mean-squared displacement do not converge for increasing number of realizations. From a systematic comparison we observe some striking similarities of the heterogeneous diffusion process with the familiar subdiffusive continuous time random walk process with power-law waiting time distribution and diverging characteristic waiting time.

  9. Diffusion processes and related topics in biology

    CERN Document Server

    Ricciardi, Luigi M

    1977-01-01

    These notes are based on a one-quarter course given at the Department of Biophysics and Theoretical Biology of the University of Chicago in 1916. The course was directed to graduate students in the Division of Biological Sciences with interests in population biology and neurobiology. Only a slight acquaintance with probability and differential equations is required of the reader. Exercises are interwoven with the text to encourage the reader to play a more active role and thus facilitate his digestion of the material. One aim of these notes is to provide a heuristic approach, using as little mathematics as possible, to certain aspects of the theory of stochastic processes that are being increasingly employed in some of the population biol­ ogy and neurobiology literature. While the subject may be classical, the nov­ elty here lies in the approach and point of view, particularly in the applica­ tions such as the approach to the neuronal firing problem and its related dif­ fusion approximations. It is a ple...

  10. A Dirichlet process mixture model for brain MRI tissue classification.

    Science.gov (United States)

    Ferreira da Silva, Adelino R

    2007-04-01

    Accurate classification of magnetic resonance images according to tissue type or region of interest has become a critical requirement in diagnosis, treatment planning, and cognitive neuroscience. Several authors have shown that finite mixture models give excellent results in the automated segmentation of MR images of the human normal brain. However, performance and robustness of finite mixture models deteriorate when the models have to deal with a variety of anatomical structures. In this paper, we propose a nonparametric Bayesian model for tissue classification of MR images of the brain. The model, known as Dirichlet process mixture model, uses Dirichlet process priors to overcome the limitations of current parametric finite mixture models. To validate the accuracy and robustness of our method we present the results of experiments carried out on simulated MR brain scans, as well as on real MR image data. The results are compared with similar results from other well-known MRI segmentation methods.

  11. Diffusion-Weighted MRI Assessment of Adjacent Disc Degeneration After Thoracolumbar Vertebral Fractures

    Energy Technology Data Exchange (ETDEWEB)

    Noriega, David C., E-mail: dcnoriega1970@gmail.com [Valladolid University Hospital, Spine Department (Spain); Marcia, Stefano, E-mail: stemarcia@gmail.com [SS. Trinità Hospital ASL 8 Cagliari, Department of Radiology (Italy); Ardura, Francisco, E-mail: fardura@ono.com [Valladolid University Hospital, Spine Department (Spain); Lite, Israel Sanchez, E-mail: israelslite@hotmail.com [Valladolid University Hospital, Radiology Department (Spain); Marras, Mariangela, E-mail: mariangela.marrasmd@gmail.com [Azienda Ospedaliero Brotzu (A.O.B.), Department of Radiology (Italy); Saba, Luca, E-mail: lucasaba@tiscali.it [Azienda Ospedaliero Universitaria (A.O.U.), Department of Radiology (Italy)

    2016-09-15

    ObjectiveThe purpose of this study was to assess, by the mean apparent diffusion coefficient (ADC), if a relationship exists between disc ADC and MR findings of adjacent disc degeneration after thoracolumbar fractures treated by anatomic reduction using vertebral augmentation (VAP).Materials and MethodsTwenty non-consecutive patients (mean age 50.7 years; range 45–56) treated because of vertebral fractures, were included in this study. There were 10 A3.1 and 10 A1.2 fractures (AO classification). Surgical treatment using VAP was applied in 14 cases, and conservative in 6 patients. MRI T2-weighted images and mapping of apparent diffusion coefficient (ADC) of the intervertebral disc adjacent to the fractured segment were performed after a mean follow-up of 32 months. A total of 60 discs, 3 per patient, were analysed: infra-adjacent, supra-adjacent and a control disc one level above the supra-adjacent.ResultsNo differences between patients surgically treated and those following a conservative protocol regarding the average ADC values obtained in the 20 control discs analysed were found. Considering all discs, average ADC in the supra-adjacent level was lower than in the infra-adjacent (1.35 ± 0.12 vs. 1.53 ± 0.06; p < 0.001). Average ADC values of the discs used as a control were similar to those of the infra-adjacent level (1.54 ± 0.06). Compared to surgically treated patients, discs at the supra-adjacent fracture level showed statistically significant lower values in cases treated conservatively (p < 0.001). The variation in the delay of surgery had no influence on the average values of ADC at any of the measured levels.ConclusionsADC measurements of the supra-adjacent discs after a mean follow-up of 32 months following thoracolumbar fractures, showed that restoration of the vertebral collapse by minimally invasive VAP prevents posttraumatic disc degeneration.

  12. Diffusion tensor imaging in evaluation of posterior fossa tumors in children on a 3T MRI scanner

    International Nuclear Information System (INIS)

    Assis, Zarina Abdul; Saini, Jitender; Ranjan, Manish; Gupta, Arun Kumar; Sabharwal, Paramveer; Naidu, Purushotham R

    2015-01-01

    Primary intracranial tumors in children are commonly located in the posterior fossa. Conventional MRI offers limited information regarding the histopathological type of tumor which is essential for better patient management. The purpose of the study was to evaluate the usefulness of advanced MR imaging techniques like diffusion tensor imaging (DTI) in distinguishing the various histopathological types of posterior fossa tumors in children. DTI was performed on a 3T MRI scanner in 34 untreated children found to have posterior fossa lesions. Using third party software, various DTI parameters [apparent diffusion coefficient (ADC), fractional anisotropy (FA), radial diffusivity, planar index, spherical index, and linear index] were calculated for the lesion. Data were subjected to statistical analysis [analysis of variance (ANOVA)] using SPSS 15.0 software. We observed significant correlation (P < 0.01) between ADC mean and maximum, followed by radial diffusivity (RD) with the histopathological types of the lesions. Rest of the DTI parameters did not show any significant correlation in our study. The results of our study support the hypothesis that most cellular tumors and those with greater nuclear area like medulloblastoma would have the lowest ADC values, as compared to less cellular tumors like pilocytic astrocytoma

  13. Detectability and detection rate of acute cerebral hemisphere infarcts on CT and diffusion-weighted MRI

    International Nuclear Information System (INIS)

    Urbach, H.; Flacke, S.; Keller, E.; Textor, J.; Berlis, A.; Reul, J.; Schild, H.H.; Hartmann, A.; Solymosi, L.

    2000-01-01

    Our purpose was to compare the detectability and detection rate of acute ischaemic cerebral hemisphere infarcts on CT and diffusion-weighted MRI (DWI). We investigated 32 consecutive patients with acute hemisphere stroke with unenhanced CT and DWI within 6 h of stroke onset. The interval between CT and DWI ranged from 15 to 180 min (mean 60 min). Infarct detectability on CT and DWI was determined by comparing the initial CT, DWI and later reference images in a consensus reading of five independent examiners. The ''true'' detection rate was assessed by analysing all single readings. Two patients had intracerebral haematomas on DWI and CT and were excluded. There were 27 patients with ischaemic infarcts; all were visible on DWI and proven by follow-up. DWI was negative in three patients without a final diagnosis of infarct (100 % sensitivity, 100 % specificity, χ 2 = 30, P 2 = 1.48, P = 0.224). With regard to the single readings (30 examinations x 5 examiners = 150 readings), 63 CT readings were true positive and 72 false negative (sensitivity 47 %, specificity 86 %, χ 2 = 2.88, P = 0.089). Of the DWI readings 128 were true positive and 7 false negative (sensitivity 95 %, specificity 87 %, χ 2 = 70.67, P < 0.0001). Interobserver agreement was substantial for CT (χ= 0.72, 95 % confidence interval, 0.6-0.84) and DWI (χ= 0.82, 95 % confidence interval, 0.46-1). Taken together, detectability and detection rate of acute (< 6 h) hemisphere infarcts are significantly higher with DWI than with CT. (orig.)

  14. Cardiomyocyte architectural plasticity in fetal, neonatal, and adult pig hearts delineated with diffusion tensor MRI.

    Science.gov (United States)

    Zhang, Lei; Allen, John; Hu, Lingzhi; Caruthers, Shelton D; Wickline, Samuel A; Chen, Junjie

    2013-01-15

    Cardiomyocyte organization is a critical determinant of coordinated cardiac contractile function. Because of the acute opening of the pulmonary circulation, the relative workload of the left ventricle (LV) and right ventricle (RV) changes substantially immediately after birth. We hypothesized that three-dimensional cardiomyocyte architecture might be required to adapt rapidly to accommodate programmed perinatal changes of cardiac function. Isolated fixed hearts from pig fetuses or pigs at midgestation, preborn, postnatal day 1 (P1), postnatal day 5, postnatal day 14 (P14), and adulthood (n = 5 for each group) were acquired for diffusion-weighted magnetic resonance imaging. Cardiomyocyte architecture was visualized by three-dimensional fiber tracking and was quantitatively evaluated by the measured helix angle (α(h)). Upon the completion of MRI, hearts were sectioned and stained with hematoxylin/eosin (H&E) to evaluate cardiomyocyte alignment, with picrosirius red to evaluate collagen content, and with anti-Ki67 to evaluate postnatal cell proliferation. The helical architecture of cardiomyocyte was observed as early as the midgestational period. Postnatal changes of cardiomyocyte architecture were observed from P1 to P14, which primary occurred in the septum and RV free wall (RVFW). In the septum, the volume ratio of LV- vs. RV-associated cardiomyocytes rapidly changed from RV-LV balanced pattern at birth to LV dominant pattern by P14. In the RVFW, subendocardial α(h) decreased by ~30° from P1 to P14. These findings indicate that the helical architecture of cardiomyocyte is developed as early as the midgestation period. Substantial and rapid adaptive changes in cardiac microarchitecture suggested considerable developmental plasticity of cardiomyocyte form and function in the postnatal period in response to altered cardiac mechanical function.

  15. WE-FG-202-11: Longitudinal Diffusion MRI for Treatment Assessment of Sarcoma Patients with Pre-Operative Radiation Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Y; Cao, M; Kamrava, M; Low, D; Sheng, K; Lamb, J; Agazaryan, N; Thomas, D; Hu, P [UCLA, Los Angeles, CA (United States)

    2016-06-15

    Purpose: Diffusion weighted MRI (DWI) is a promising imaging technique for early prediction of tumor response to radiation therapy. A recently proposed longitudinal DWI strategy using a Co-60 MRI guided RT system (MRIgRT) may bring functional MRI guided adaptive radiation therapy closer to clinical utility. We report our preliminary results of using this longitudinal DWI approach performed on the MRIgRT system for predicting the response of sarcoma patient to preop RT. Methods: Three sarcoma patients who underwent fractionated IMRT were recruited in this study. For all three patients DWI images were acquired immediately following his/her treatment. For each imaging session, ten slices were acquired interleaved with the b values covering the gross tumor volume (GTV). The diffusion images were processed to obtain the ADC maps using standard exponential fitting for each voxel. Regions of interest were drawn in the tumor on the diffusion images based on each patient’s clinical GTV contours. Each patient subsequently underwent surgery and the tumor necrosis score was available from standard pathology. The ADC values for each patient were compared to the necrosis scores to assess the predictive value of our longitudinal DWI for tumor response. Results: Each patient underwent 3 to 5 diffusion MRI scans depending on their treatment length. Patient 1 had a relatively unchanged ADC during the course of RT and a necrosis score of 30% at surgery. For patient 2, the mean ADC values decreased from 1.56 × 10-3 to 1.12 × 10-3 mm2/s and the patient’s necrosis score was less than 10%. Patient 3 had a slight increase in the ADC values from 0.59 × 10-3 to 0.71 × 10-3 mm2/s and patient’s necrosis score was 50%. Conclusion: Based on limited data from 3 patients, our longitudinal changes in tumor ADC assessed using the MRIgRT system correlated well with pathology results.

  16. Interestingness-Driven Diffusion Process Summarization in Dynamic Networks

    DEFF Research Database (Denmark)

    Qu, Qiang; Liu, Siyuan; Jensen, Christian S.

    2014-01-01

    The widespread use of social networks enables the rapid diffusion of information, e.g., news, among users in very large communities. It is a substantial challenge to be able to observe and understand such diffusion processes, which may be modeled as networks that are both large and dynamic. A key...... tool in this regard is data summarization. However, few existing studies aim to summarize graphs/networks for dynamics. Dynamic networks raise new challenges not found in static settings, including time sensitivity and the needs for online interestingness evaluation and summary traceability, which...... render existing techniques inapplicable. We study the topic of dynamic network summarization: how to summarize dynamic networks with millions of nodes by only capturing the few most interesting nodes or edges over time, and we address the problem by finding interestingness-driven diffusion processes...

  17. Solute coupled diffusion in osmotically driven membrane processes.

    Science.gov (United States)

    Hancock, Nathan T; Cath, Tzahi Y

    2009-09-01

    Forward osmosis (FO) is an emerging water treatment technology with potential applications in desalination and wastewater reclamation. In FO, water is extracted from a feed solution using the high osmotic pressure of a hypertonic solution that flows on the opposite side of a semipermeable membrane; however, solutes diffuse simultaneously through the membrane in both directions and may jeopardize the process. In this study, we have comprehensively explored the effects of different operating conditions on the forward diffusion of solutes commonly found in brackish water and seawater, and reverse diffusion of common draw solution solutes. Results show that reverse transport of solutes through commercially available FO membranes range between 80 mg to nearly 3,000 mg per liter of water produced. Divalent feed solutes have low permeation rates (less than 1 mmol/m2-hr) while monovalent ions and uncharged solutes exhibit higher permeation. Findings have significant implications on the performance and sustainability of the FO process.

  18. Hardfacing of duplex stainless steel using melting and diffusion processes

    Science.gov (United States)

    Lailatul, H.; Maleque, M. A.

    2017-03-01

    Duplex stainless steel (DSS) is a material with high potential successes in many new applications such as rail car manufacturing, automotive and chemical industries. Although DSS is widely used in various industries, this material has faced wear and hardness problems which obstruct a wider capability of this material and causes problems in current application. Therefore, development of surface modification has been introduced to produce hard protective layer or coating on DSS. The main aim of this work is to brief review on hard surface layer formation on DSS using melting and diffusion processes. Melting technique using tungsten inert gas (TIG) torch and diffusion technique using gas nitriding are the effective process to meet this requirement. The processing route plays a significant role in developing the hard surface layer for any application with effective cost and environmental factors. The good understanding and careful selection of processing route to form products are very important factors to decide the suitable techniques for surface engineering treatment. In this paper, an attempt is also made to consolidate the important research works done on melting and diffusion techniques of DSS in the past. The advantages and disadvantages between melting and diffusion technique are presented for better understanding on the feasibility of hard surface formation on DSS. Finally, it can be concluded that this work will open an avenue for further research on the application of suitable process for hard surface formation on DSS.

  19. Whole body MRI, including diffusion-weighted imaging in follow-up of patients with testicular cancer.

    Science.gov (United States)

    Mosavi, Firas; Laurell, Anna; Ahlström, Håkan

    2015-11-01

    Whole body (WB) magnetic resonance imaging (MRI), including diffusion-weighted imaging (DWI) has become increasingly utilized in cancer imaging, yet the clinical utility of these techniques in follow-up of testicular cancer patients has not been evaluated. The purpose of this study was to evaluate the feasibility of WB MRI with continuous table movement (CTM) technique, including multistep DWI in follow-up of patients with testicular cancer. WB MRI including DWI was performed in follow-up of 71 consecutive patients (median age, 37 years; range 19-84) with histologically confirmed testicular cancer. WB MRI protocol included axial T1-Dixon and T2-BLADE sequences using CTM technique. Furthermore, multi-step DWI was performed using b-value 50 and 1000 s/mm(2). One criterion for feasibility was patient tolerance and satisfactory image quality. Another criterion was the accuracy in detection of any pathological mass, compared to standard of reference. Signal intensity in DWI was used for evaluation of residual mass activity. Clinical, laboratory and imaging follow-up were applied as standard of reference for the evaluation of WB MRI. WB MRI was tolerated in nearly all patients (69/71 patients, 97%) and the image quality was satisfactory. Metal artifacts deteriorated the image quality in six patients, but it did not influence the overall results. No case of clinical relapse was observed during the follow-up time. There was a good agreement between conventional WB MRI and standard of reference in all patients. Three patients showed residual masses and DWI signal was not restricted in these patients. Furthermore, DWI showed abnormally high signal intensity in a normal-sized retroperitoneal lymph node indicating metastasis. The subsequent (18)F-FDG PET/CT could verify the finding. WB MRI with CTM technique including multi-step DWI is feasible in follow-up of patients with testicular cancer. DWI may contribute to important added-value data to conventional MRI sequences

  20. Effectiveness of 3 T PROPELLER DUO diffusion-weighted MRI in differentiating sinonasal lymphomas and carcinomas

    International Nuclear Information System (INIS)

    Wang, X.; Zhang, Z.; Chen, Q.; Li, J.; Xian, J.

    2014-01-01

    Aim: To evaluate the value of 3 T Periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) DUO diffusion-weighted MRI (DW-MRI) in differentiating sinonasal lymphomas from carcinomas. Materials and methods: PROPELLER DUO DW-MRI was performed in 23 patients with sinonasal lymphomas and 28 patients with carcinomas histologically confirmed at 3 T MRI. Apparent diffusion coefficients (ADCs) were obtained with two different b-values (b = 0 and 700 s/mm 2 , b = 0 and 1000 s/mm 2 ) and two different regions of interest (ROIs) sampling strategies [whole section (WS), partial section (PS)], respectively. Difference in ADCs between sinonasal lymphomas and carcinomas was evaluated using the independent samples t-test or Mann–Whitney U-test. The utility of ADC thresholds for discriminating between them was evaluated by receiver operating characteristic analysis. Results: ADCs of sinonasal lymphomas (WS ADC b0,700 , 0.838 × 10 −3  mm 2 /s) were significantly (p < 0.001) lower than those of carcinomas (WS ADC b0,700 , 1.396 × 10 −3  mm 2 /s). Using a WS ADC b0,700 value of 1.040 × 10 −3  mm 2 /s as the threshold value effectively differentiated sinonasal lymphomas from carcinomas with 100% sensitivity, 82.1% specificity, and 82.1% positive and 100% negative predictive values and 90.2% accuracy (b = 0, 700 s/mm 2 ). There was no significant difference in diagnostic ability between different b-values settings (p > 0.05) and different sampling strategies of ROIs (p > 0.05), respectively. Additionally, there was significant differences in the ADCs between diffuse large B-cell lymphomas and natural killer (NK)/T-cell lymphomas (p < 0.05). Conclusion: PROPELLER DUO DW-MRI can effectively differentiate sinonasal lymphomas from carcinomas. - Highlights: • ADCs of sinonasal lymphomas were lower than those of carcinomas. • ADCs might effectively differentiate sinonasal lymphomas from carcinomas. • Diffuse large B

  1. Membrane formation : diffusion induced demixing processes in ternary polymeric systems

    NARCIS (Netherlands)

    Reuvers, Albertus Johannes

    1987-01-01

    In this thesis the mechanism of membrane formation by means of immersion precipitation is studied. Immersion of a concentrated polymer solution film into a nonsolvent bath induces an exchange of solvent and nonsolvent in the film by means of diffusion. This process results in an asymmetric polymer

  2. Emptiness formation probability of XX-chain in diffusion process

    International Nuclear Information System (INIS)

    Ogata, Yoshiko

    2004-01-01

    We study the distribution of emptiness formation probability of XX-model in the diffusion process. There exits a Gaussian decay as well as an exponential decay. The Gaussian decay is caused by the existence of zero point in the Fermi distribution function. The correlation length for each point of scaling factor varies up to the initial condition, monotonically or non-monotonically

  3. Magnetic resonance imaging (MRI) in diffuse liver diseases. Comparison with CT

    Energy Technology Data Exchange (ETDEWEB)

    Yoshikawa, Masaharu; Ebara, Masaaki; Ohto, Masao

    1987-06-01

    MRI (Magnetic Resonance Imaging) was performed in 74 patients with chronic hepatitis, liver cirrhosis, idiopathic portal hypertension, Budd-Chiari syndrome, extrahepatic protal vein occlusion, Wilson disease and hemochromatosis. We measured relaxation time of the liver and the spleen in these patients and compared MRI with CT in the diagnostic capability. MRI was superior to plain CT in the detection of collateral vessels in liver cirrhosis and extrahepatic protal vein occlusion. MRI could also demonstrate the occluded part of the inferior vena cava in Budd-Chiari syndrome. However, MRI was almost the same as CT in the visualization of the hepatic configuration in liver cirrhosis. In liver cirrhosis, T1 values of the liver and the spleen were longer than those in normal controls, and T1 values of the liver were correlated with ICG R-15. Hepatic T1 values in Budd-Chiari syndrome were longer than those in normal controls.

  4. Gadoxetic acid-enhanced MRI and diffusion-weighted imaging for the detection of colorectal liver metastases after neoadjuvant chemotherapy

    International Nuclear Information System (INIS)

    Yu, Mi Hye; Lee, Jeong Min; Han, Joon Koo; Choi, Byung-Ihn; Hur, Bo Yun; Kim, Tae-You; Jeong, Seung-Yong; Yi, Nam-Joon; Suh, Kyung-Suk

    2015-01-01

    To investigate the diagnostic performance of gadoxetic acid-enhanced MRI including diffusion-weighted imaging (DWI) for the detection of colorectal liver metastases (CRLMs) after neoadjuvant chemotherapy (NAC). Our study population comprised 77 patients with 140 CRLMs who underwent gadoxetic acid-enhanced MRI within 1 month prior to surgery: group A (without NAC, n = 38) and group B (with NAC, n = 39). Two radiologists independently assessed all MR images and graded their diagnostic confidence for CRLM on a 5-point scale. Diagnostic accuracy, sensitivity and positive predictive values (PPV) were calculated and compared between the two groups. Diagnostic accuracy of gadoxetic acid-enhanced MRI in group B was slightly lower than in group A, but a statistically significant difference was not observed (observer 1: A z , 0.926 in group A, 0.905 in group B; observer 2: A z , 0.944 in group A, 0.885 in group B; p > 0.05). Sensitivity and PPV of group B were comparable to those of group A (observer 1: sensitivity = 93.5 % vs. 93.6 %, PPV = 95.1 % vs. 86.9 %; observer 2: sensitivity = 96.8 % vs. 91.0 %; PPV = 90.0 % vs. 89.7 %; all p > 0.05). Gadoxetic acid-enhanced MRI including DWI provided good diagnostic performance with high sensitivity (>90 %) for the detection of CRLMs, regardless of the influence of NAC. (orig.)

  5. Effects on atmospheric diffusion of meterological processes in coastal zones

    International Nuclear Information System (INIS)

    Raynor, G.S.

    1977-01-01

    Meteorological processes in coastal zones differ from those inland because of the surface discontinuity between land and water. The difference in heating between the two surfaces gives rise to sea or lake breeze circulations which can transport pollutants in nongradient directions and recirculate them over source areas. The step change in surface characteristics at the land-water interface also causes formation of internal boundary layers having different transport velocities and diffusion rates than unmodified air upwind or above the boundary. These features require a more extensive measurement program and more versatile diffusion models than at inland sites

  6. Modelling and simulation of diffusive processes methods and applications

    CERN Document Server

    Basu, SK

    2014-01-01

    This book addresses the key issues in the modeling and simulation of diffusive processes from a wide spectrum of different applications across a broad range of disciplines. Features: discusses diffusion and molecular transport in living cells and suspended sediment in open channels; examines the modeling of peristaltic transport of nanofluids, and isotachophoretic separation of ionic samples in microfluidics; reviews thermal characterization of non-homogeneous media and scale-dependent porous dispersion resulting from velocity fluctuations; describes the modeling of nitrogen fate and transport

  7. XQ-NLM: Denoising Diffusion MRI Data via x-q Space Non-Local Patch Matching.

    Science.gov (United States)

    Chen, Geng; Wu, Yafeng; Shen, Dinggang; Yap, Pew-Thian

    2016-10-01

    Noise is a major issue influencing quantitative analysis in diffusion MRI. The effects of noise can be reduced by repeated acquisitions, but this leads to long acquisition times that can be unrealistic in clinical settings. For this reason, post-acquisition denoising methods have been widely used to improve SNR. Among existing methods, non-local means (NLM) has been shown to produce good image quality with edge preservation. However, currently the application of NLM to diffusion MRI has been mostly focused on the spatial space (i.e., the x -space), despite the fact that diffusion data live in a combined space consisting of the x -space and the q -space (i.e., the space of wavevectors). In this paper, we propose to extend NLM to both x -space and q -space. We show how patch-matching, as required in NLM, can be performed concurrently in x-q space with the help of azimuthal equidistant projection and rotation invariant features. Extensive experiments on both synthetic and real data confirm that the proposed x-q space NLM (XQ-NLM) outperforms the classic NLM.

  8. Incremental value of diffusion weighted and dynamic contrast enhanced MRI in the detection of locally recurrent prostate cancer after radiation treatment: preliminary results

    International Nuclear Information System (INIS)

    Akin, Oguz; Vargas, Hebert Alberto; Hricak, Hedvig; Gultekin, David H.; Zheng, Junting; Moskowitz, Chaya; Pei, Xin; Sperling, Dahlia; Zelefsky, Michael J.; Schwartz, Lawrence H.

    2011-01-01

    To assess the incremental value of diffusion-weighted (DW-MRI) and dynamic contrast-enhanced MRI (DCE-MRI) to T2-weighted MRI (T2WI) in detecting locally recurrent prostate cancer after radiotherapy. Twenty-four patients (median age, 70 years) with a history of radiotherapy-treated prostate cancer underwent multi-parametric MRI (MP-MRI) and transrectal prostate biopsy. Two readers independently scored the likelihood of cancer on a 1-5 scale, using T2WI alone and then adding DW-MRI and DCE-MRI. Areas under receiver operating characteristic curves (AUCs) were estimated at the patient and prostate-side levels. The apparent diffusion coefficient (ADC) from DW-MRI and the K trans , k ep , v e , AUGC90 and AUGC180 from DCE-MRI were recorded. Biopsy was positive in 16/24 (67%) and negative in 8/24 (33%) patients. AUCs for readers 1 and 2 increased from 0.64 and 0.53 to 0.95 and 0.86 with MP-MRI, at the patient level, and from 0.73 and 0.66 to 0.90 and 0.79 with MP-MRI, at the prostate-side level (p values -3 mm 2 /s)], median K trans [1.07 vs. 0.34 (1/min)], and k ep [2.06 vs 1.0 (1/min)] (p values < 0.05). MP-MRI was significantly more accurate than T2WI alone in detecting locally recurrent prostate cancer after radiotherapy. (orig.)

  9. Incremental value of diffusion weighted and dynamic contrast enhanced MRI in the detection of locally recurrent prostate cancer after radiation treatment: preliminary results

    Energy Technology Data Exchange (ETDEWEB)

    Akin, Oguz; Vargas, Hebert Alberto; Hricak, Hedvig [Memorial Sloan-Kettering Cancer Center, Department of Radiology, New York, NY (United States); Gultekin, David H. [Memorial Sloan-Kettering Cancer Center, Medical Physics, New York, NY (United States); Zheng, Junting; Moskowitz, Chaya [Memorial Sloan-Kettering Cancer Center, Epidemiology and Biostatistics, New York, NY (United States); Pei, Xin; Sperling, Dahlia; Zelefsky, Michael J. [Memorial Sloan-Kettering Cancer Center, Radiation Oncology, New York, NY (United States); Schwartz, Lawrence H. [Columbia University College of Physicians and Surgeons, Radiology, New York, NY (United States)

    2011-09-15

    To assess the incremental value of diffusion-weighted (DW-MRI) and dynamic contrast-enhanced MRI (DCE-MRI) to T2-weighted MRI (T2WI) in detecting locally recurrent prostate cancer after radiotherapy. Twenty-four patients (median age, 70 years) with a history of radiotherapy-treated prostate cancer underwent multi-parametric MRI (MP-MRI) and transrectal prostate biopsy. Two readers independently scored the likelihood of cancer on a 1-5 scale, using T2WI alone and then adding DW-MRI and DCE-MRI. Areas under receiver operating characteristic curves (AUCs) were estimated at the patient and prostate-side levels. The apparent diffusion coefficient (ADC) from DW-MRI and the K{sup trans}, k{sub ep}, v{sub e}, AUGC90 and AUGC180 from DCE-MRI were recorded. Biopsy was positive in 16/24 (67%) and negative in 8/24 (33%) patients. AUCs for readers 1 and 2 increased from 0.64 and 0.53 to 0.95 and 0.86 with MP-MRI, at the patient level, and from 0.73 and 0.66 to 0.90 and 0.79 with MP-MRI, at the prostate-side level (p values < 0.05). Biopsy-positive and biopsy-negative prostate sides differed significantly in median ADC [1.44 vs. 1.68 (x 10{sup -3} mm{sup 2}/s)], median K{sup trans} [1.07 vs. 0.34 (1/min)], and k{sub ep} [2.06 vs 1.0 (1/min)] (p values < 0.05). MP-MRI was significantly more accurate than T2WI alone in detecting locally recurrent prostate cancer after radiotherapy. (orig.)

  10. Promoting information diffusion through interlayer recovery processes in multiplex networks

    Science.gov (United States)

    Wang, Xin; Li, Weihua; Liu, Longzhao; Pei, Sen; Tang, Shaoting; Zheng, Zhiming

    2017-09-01

    For information diffusion in multiplex networks, the effect of interlayer contagion on spreading dynamics has been explored in different settings. Nevertheless, the impact of interlayer recovery processes, i.e., the transition of nodes to stiflers in all layers after they become stiflers in any layer, still remains unclear. In this paper, we propose a modified ignorant-spreader-stifler model of rumor spreading equipped with an interlayer recovery mechanism. We find that the information diffusion can be effectively promoted for a range of interlayer recovery rates. By combining the mean-field approximation and the Markov chain approach, we derive the evolution equations of the diffusion process in two-layer homogeneous multiplex networks. The optimal interlayer recovery rate that achieves the maximal enhancement can be calculated by solving the equations numerically. In addition, we find that the promoting effect on a certain layer can be strengthened if information spreads more extensively within the counterpart layer. When applying the model to two-layer scale-free multiplex networks, with or without degree correlation, similar promoting effect is also observed in simulations. Our work indicates that the interlayer recovery process is beneficial to information diffusion in multiplex networks, which may have implications for designing efficient spreading strategies.

  11. IgG4-related kidney disease: MRI findings with emphasis on the usefulness of diffusion-weighted imaging

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Bohyun; Kim, Jin Hee, E-mail: kimjhrad@amc.seoul.kr; Byun, Jae Ho; Kim, Hyoung Jung; Lee, Seung Soo; Kim, So Yeon; Lee, Moon-Gyu

    2014-07-15

    Objectives: To investigate the imaging findings of immunoglobulin G4 (IgG4)-related kidney disease (IgG4-KD) on magnetic resonance imaging (MRI) including diffusion-weighted imaging (DWI) and to evaluate the usefulness of DWI in lesion detection. Methods: This retrospective cohort study included 31 patients with IgG4-KD who underwent MRI covering both kidneys. Two radiologists reviewed in consensus the MR images to determine the distribution pattern (location, laterality, and multiplicity) and the visually assessed signal intensity (hypointense, isointense or hyperintense) of the renal lesions compared to the normal renal parenchyma on each sequence. Per-patient sensitivity for detecting IgG4-KD and the number of detectable lesions were compared in T2-weighted images, DWI, and dynamic contrast-enhanced images. Results: IgG4-KD typically manifested as bilateral (83.9%), multiple (93.5%), and renal parenchymal (87.1%) nodules appearing isointense (93.5%) on T1-weighted images, hypointense (77.4%) on T2-weighted images, hyperintense (100%) on DWI (b = 1000), and hypointense (83.3%) in the arterial phase and with a progressive enhancement pattern on dynamic contrast-enhanced images. The sensitivity of DWI for detecting IgG4-KD was significantly higher than that of T2-weighted images (100% vs. 77.4%, P = 0.034). The median number of detectable lesions was significantly greater in DWI (n = 9) than in T2-weighted images (n = 2) and dynamic contrast-enhanced images (n = 5) (P ≤ 0.008). Conclusions: The characteristic MRI findings of IgG4-KD were bilateral, multiple, renal parenchymal nodules with T2 hypointensity, diffusion restriction, and a progressive enhancement pattern. As DWI was useful in the detection of IgG4-KD, adding DWI to conventional MRI for patients suspected of having IgG4-KD may enhance the diagnosis.

  12. IgG4-related kidney disease: MRI findings with emphasis on the usefulness of diffusion-weighted imaging

    International Nuclear Information System (INIS)

    Kim, Bohyun; Kim, Jin Hee; Byun, Jae Ho; Kim, Hyoung Jung; Lee, Seung Soo; Kim, So Yeon; Lee, Moon-Gyu

    2014-01-01

    Objectives: To investigate the imaging findings of immunoglobulin G4 (IgG4)-related kidney disease (IgG4-KD) on magnetic resonance imaging (MRI) including diffusion-weighted imaging (DWI) and to evaluate the usefulness of DWI in lesion detection. Methods: This retrospective cohort study included 31 patients with IgG4-KD who underwent MRI covering both kidneys. Two radiologists reviewed in consensus the MR images to determine the distribution pattern (location, laterality, and multiplicity) and the visually assessed signal intensity (hypointense, isointense or hyperintense) of the renal lesions compared to the normal renal parenchyma on each sequence. Per-patient sensitivity for detecting IgG4-KD and the number of detectable lesions were compared in T2-weighted images, DWI, and dynamic contrast-enhanced images. Results: IgG4-KD typically manifested as bilateral (83.9%), multiple (93.5%), and renal parenchymal (87.1%) nodules appearing isointense (93.5%) on T1-weighted images, hypointense (77.4%) on T2-weighted images, hyperintense (100%) on DWI (b = 1000), and hypointense (83.3%) in the arterial phase and with a progressive enhancement pattern on dynamic contrast-enhanced images. The sensitivity of DWI for detecting IgG4-KD was significantly higher than that of T2-weighted images (100% vs. 77.4%, P = 0.034). The median number of detectable lesions was significantly greater in DWI (n = 9) than in T2-weighted images (n = 2) and dynamic contrast-enhanced images (n = 5) (P ≤ 0.008). Conclusions: The characteristic MRI findings of IgG4-KD were bilateral, multiple, renal parenchymal nodules with T2 hypointensity, diffusion restriction, and a progressive enhancement pattern. As DWI was useful in the detection of IgG4-KD, adding DWI to conventional MRI for patients suspected of having IgG4-KD may enhance the diagnosis

  13. WE-FG-202-08: Assessment of Treatment Response Via Longitudinal Diffusion MRI On A MRI-Guided System: Initial Experience of Quantitative Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Qi, X; Yang, Y; Yang, L; Low, D; Sheng, K [UCLA, Los Angeles, CA (United States)

    2016-06-15

    Purpose: To report our initial experience of systematic monitoring treatment response using longitudinal diffusion MR images on a Co-60 MRI-guided radiotherapy system. Methods: Four patients, including 2 head-and-necks, 1 sarcoma and 1 GBM treated on a 0.35 Tesla MRI-guided treatment system, were analyzed. For each patient, 3D TrueFISP MRIs were acquired during CT simulation and before each treatment for treatment planning and patient setup purposes respectively. Additionally, 2D diffusion-weighted MR images (DWI) were acquired weekly throughout the treatment course. The gross target volume (GTV) and brainstem (as a reference structure) were delineated on weekly 3D TrueFISP MRIs to monitor anatomy changes, the contours were then transferred onto the corresponding DWI images after fusing with the weekly TrueFISP images. The patient-specific temporal and spatial variations during the entire treatment course, such as anatomic changes, target apparent diffusion coefficient (ADC) distribution were evaluated in a longitudinal pattern. Results: Routine MRI revealed progressive soft-tissue GTV volume changes (up to 53%) for the H&N cases during the treatment course of 5–7 weeks. Within the GTV, the mean ADC values varied from −44% (ADC decrease) to +26% (ADC increase) in a week. The gradual increase of ADC value was inversely associated with target volume variation for one H&N case. The maximal changes of mean ADC values within the brainstem were 5.3% for the H&N cases. For the large size sarcoma and GBM tumors, spatial heterogeneity and temporal variations were observed through longitudinal ADC analysis. Conclusion: In addition to the superior soft-tissue visualization, the 0.35T MR system on ViewRay showed the potential to quantitatively measure the ADC values for both tumor and normal tissues. For normal tissue that is minimally affected by radiation, its ADC values are reproducible. Tumor ADC values show temporal and spatial fluctuation that can be exploited for

  14. Functional MRI of music emotion processing in frontotemporal dementia.

    Science.gov (United States)

    Agustus, Jennifer L; Mahoney, Colin J; Downey, Laura E; Omar, Rohani; Cohen, Miriam; White, Mark J; Scott, Sophie K; Mancini, Laura; Warren, Jason D

    2015-03-01

    Frontotemporal dementia is an important neurodegenerative disorder of younger life led by profound emotional and social dysfunction. Here we used fMRI to assess brain mechanisms of music emotion processing in a cohort of patients with frontotemporal dementia (n = 15) in relation to healthy age-matched individuals (n = 11). In a passive-listening paradigm, we manipulated levels of emotion processing in simple arpeggio chords (mode versus dissonance) and emotion modality (music versus human emotional vocalizations). A complex profile of disease-associated functional alterations was identified with separable signatures of musical mode, emotion level, and emotion modality within a common, distributed brain network, including posterior and anterior superior temporal and inferior frontal cortices and dorsal brainstem effector nuclei. Separable functional signatures were identified post-hoc in patients with and without abnormal craving for music (musicophilia): a model for specific abnormal emotional behaviors in frontotemporal dementia. Our findings indicate the potential of music to delineate neural mechanisms of altered emotion processing in dementias, with implications for future disease tracking and therapeutic strategies. © 2014 The Authors. Annals of the New York Academy of Sciences published by Wiley Periodicals Inc. on behalf of The New York Academy of Sciences.

  15. A tutorial on inverse problems for anomalous diffusion processes

    International Nuclear Information System (INIS)

    Jin, Bangti; Rundell, William

    2015-01-01

    Over the last two decades, anomalous diffusion processes in which the mean squares variance grows slower or faster than that in a Gaussian process have found many applications. At a macroscopic level, these processes are adequately described by fractional differential equations, which involves fractional derivatives in time or/and space. The fractional derivatives describe either history mechanism or long range interactions of particle motions at a microscopic level. The new physics can change dramatically the behavior of the forward problems. For example, the solution operator of the time fractional diffusion diffusion equation has only limited smoothing property, whereas the solution for the space fractional diffusion equation may contain weak singularity. Naturally one expects that the new physics will impact related inverse problems in terms of uniqueness, stability, and degree of ill-posedness. The last aspect is especially important from a practical point of view, i.e., stably reconstructing the quantities of interest. In this paper, we employ a formal analytic and numerical way, especially the two-parameter Mittag-Leffler function and singular value decomposition, to examine the degree of ill-posedness of several ‘classical’ inverse problems for fractional differential equations involving a Djrbashian–Caputo fractional derivative in either time or space, which represent the fractional analogues of that for classical integral order differential equations. We discuss four inverse problems, i.e., backward fractional diffusion, sideways problem, inverse source problem and inverse potential problem for time fractional diffusion, and inverse Sturm–Liouville problem, Cauchy problem, backward fractional diffusion and sideways problem for space fractional diffusion. It is found that contrary to the wide belief, the influence of anomalous diffusion on the degree of ill-posedness is not definitive: it can either significantly improve or worsen the conditioning

  16. ¹⁸F-FDG PET metabolic parameters and MRI perfusion and diffusion parameters in hepatocellular carcinoma: a preliminary study.

    Directory of Open Access Journals (Sweden)

    Sung Jun Ahn

    Full Text Available OBJECTIVES: Glucose metabolism, perfusion, and water diffusion may have a relationship or affect each other in the same tumor. The understanding of their relationship could expand the knowledge of tumor characteristics and contribute to the field of oncologic imaging. The purpose of this study was to evaluate the relationships between metabolism, vasculature and cellularity of advanced hepatocellular carcinoma (HCC, using multimodality imaging such as ¹⁸F-FDG positron emission tomography (PET, dynamic contrast enhanced (DCE-MRI, and diffusion weighted imaging(DWI. MATERIALS AND METHODS: Twenty-one patients with advanced HCC underwent ¹⁸F-FDG PET, DCE-MRI, and DWI before treatment. Maximum standard uptake values (SUV(max from ¹⁸F-FDG-PET, variables of the volume transfer constant (K(trans from DCE-MRI and apparent diffusion coefficient (ADC from DWI were obtained for the tumor and their relationships were examined by Spearman's correlation analysis. The influence of portal vein thrombosis on SUV(max and variables of K(trans and ADC was evaluated by Mann-Whitney test. RESULTS: SUV(max showed significant negative correlation with K(trans(max (ρ = -0.622, p = 0.002. However, variables of ADC showed no relationship with variables of K(trans or SUV(max (p>0.05. Whether portal vein thrombosis was present or not did not influence the SUV max and variables of ADC and K(trans (p>0.05. CONCLUSION: In this study, SUV was shown to be correlated with K(trans in advanced HCCs; the higher the glucose metabolism a tumor had, the lower the perfusion it had, which might help in guiding target therapy.

  17. Option Pricing with Stochastic Volatility and Jump Diffusion Processes

    Directory of Open Access Journals (Sweden)

    Radu Lupu

    2006-03-01

    Full Text Available Option pricing by the use of Black Scholes Merton (BSM model is based on the assumption that asset prices have a lognormal distribution. In spite of the use of these models on a large scale, both by practioners and academics, the assumption of lognormality is rejected by the history of returns. The objective of this article is to present the methods that developed after the Black Scholes Merton environment and deals with the option pricing model adjustment to the empirical properties of asset returns. The main models that appeared after BSM allowed for special changes of the returns that materialized in jump-diffusion and stochastic volatility processes. The article presents the foundations of risk neutral options evaluation and the empirical evidence that fed the amendment of the lognormal assumption in the first part and shows the evaluation procedure under the assumption of stock prices following the jump-diffusion process and the stochastic volatility process.

  18. Quantitative evaluation of the tibial tunnel after anterior cruciate ligament reconstruction using diffusion weighted and dynamic contrast enhanced MRI: a follow-up feasibility study

    Energy Technology Data Exchange (ETDEWEB)

    Rupreht, Mitja; Seruga, Tomaz; Jevsek, Marko [University Medical Centre Maribor, Radiology Department, Maribor (Slovenia); Jevtic, Vladimir [University of Ljubljana, Medical Faculty, Ljubljana (Slovenia); Sersa, Igor [Jozef Stefan Institute, MRI Laboratory, Ljubljana (Slovenia); Vogrin, Matjaz [University of Medical Centre of Maribor, Department of Orthopaedics, Maribor (Slovenia)

    2012-05-15

    The aim of the study was to evaluate the feasibility of two quantitative MRI methods: diffusion weighted imaging (DWI) and dynamic contrast enhanced imaging (DCEI), for follow-up assessment of the tibial tunnel after reconstruction of the anterior cruciate ligament (ACL). Twenty-three patients were examined by MRI at 1 and 6 months following ACL reconstruction. DWI and DCEI were utilized for evaluating the region of interest (ROI) within the proximal part of the tibial tunnel. From the resulting apparent diffusion coefficient (ADC) maps, ADC values were calculated. DCEI data were used to extract the enhancement factor (f{sub enh}) and the enhancement gradient (g{sub enh}) for the same ROI. Calculated ADC as well as the f{sub enh} and g{sub enh} had diminished to a statistically significant extent by 6 months after ACL reconstruction. The average ADC value diminished from 1.48 (10{sup -3} mm{sup 2}/s) at 1 month to 1.30 (10{sup -3} mm{sup 2}/s) at 6 months after reconstruction. The average f{sub enh} value decreased from 1.21 at 1 month to 0.50 at 6 months and the average g{sub enh} value decreased from 2.01%/s to 1.15%/s at 6 months, respectively. The study proved feasibility of DWI and DCEI for quantitative assessment of the tibial tunnel at 1 and 6 months after ACL reconstruction. Both methods have the potential for use as an additional tool in the evaluation of new methods of ACL reconstruction. To our knowledge, this is the first time quantitative MRI has been used in the follow-up to the ACL graft healing process. (orig.)

  19. Detection of hepatocellular carcinoma in gadoxetic acid-enhanced MRI and diffusion-weighted MRI with respect to the severity of liver cirrhosis

    International Nuclear Information System (INIS)

    Kim, Ah Yeong; Kim, Young Kon; Lee, Min Woo; Park, Min Jung; Hwang, Jiyoung; Lee, Mi Hee; Lee, Jae Won

    2012-01-01

    Background As gadoxetic acid-enhanced magnetic resonance imaging (MRI) and diffusion-weighted imaging (DWI) have been widely used for the evaluation of hepatocellular carcinoma (HCC), it is clinically relevant to determine the diagnostic efficacy of gadoxetic acid-enhanced MRI and DWI for detection of HCCs with respect to the severity of liver cirrhosis. Purpose To compare the diagnostic accuracy and sensitivity of gadoxetic acid-enhanced MRI and DWI for detection of HCCs with respect to the severity of liver cirrhosis. Material and Methods A total of 189 patients with 240 HCCs (≤3.0 cm) (Child-Pugh A, 81 patients with 90 HCCs; Child-Pugh B, 65 patients with 85 HCCs; Child-Pugh C, 43 patients with 65 HCCs) underwent DWI and gadoxetic acid-enhanced MRI at 3.0 T. A gadoxetic acid set (dynamic and hepatobiliary phase plus T2-weighted image) and DWI set (DWI plus unenhanced MRIs) for each Child-Pugh class were analyzed independently by two observers for detecting HCCs using receiver-operating characteristic analysis. The diagnostic accuracy and sensitivity were calculated. Results There was a trend toward decreased diagnostic accuracy for gadoxetic acid and DWI set with respect to the severity of cirrhosis (Child-Pugh A [mean 0.974, 0.961], B [mean 0.904, 0.863], C [mean 0.779, 0.760]). For both observers, the sensitivities of both image sets were highest in Child-Pugh class A (mean 95.6%, 93.9%), followed by class B (mean 83.0%, 77.1%), and class C (mean 60.6%, 60.0%) (P < 0.05). Conclusion In HCC detection, the diagnostic accuracy and sensitivity for gadoxetic acid-enhanced MRI and DWI were highest in Child-Pugh class A, followed by Child-Pugh class B, and Child-Pugh class C, indicating a tendency toward decreased diagnostic capability with the severity of cirrhosis

  20. Surface-based reconstruction and diffusion MRI in the assessment of gray and white matter damage in multiple sclerosis

    Science.gov (United States)

    Caffini, Matteo; Bergsland, Niels; LaganÃ, Marcella; Tavazzi, Eleonora; Tortorella, Paola; Rovaris, Marco; Baselli, Giuseppe

    2014-03-01

    Despite advances in the application of nonconventional MRI techniques in furthering the understanding of multiple sclerosis pathogenic mechanisms, there are still many unanswered questions, such as the relationship between gray and white matter damage. We applied a combination of advanced surface-based reconstruction and diffusion tensor imaging techniques to address this issue. We found significant relationships between white matter tract integrity indices and corresponding cortical structures. Our results suggest a direct link between damage in white and gray matter and contribute to the notion of gray matter loss relating to clinical disability.

  1. Validity of apparent diffusion coefficient hyperpolarized 3He-MRI using MSCT and pulmonary function tests as references

    DEFF Research Database (Denmark)

    Diaz, Sandra; Casselbrant, Ingrid; Piitulainen, Eeva

    2008-01-01

    from MSCT. Both mean ADC and MSCT data were compared to PFT, especially percent of predicted diffusing capacity of carbon monoxide (%predicted DLCO), using Pearson's correlation test. RESULTS: Mean ADC and standard deviation values were 0.392+/-0.119 cm(2)/s for the established emphysema group and 0....... Correlations between mean ADC and EI and 15th percentile were both r=0.90 and for MLD r=0.59. There was higher correlation between mean ADC and %predicted DLCO (r=0.90) than between EI and %predicted DLCO (r=0.76). CONCLUSION: HP (3)He-MRI correlates well with density measurements from MSCT and agrees better...

  2. Diffusion

    International Nuclear Information System (INIS)

    Kubaschewski, O.

    1983-01-01

    The diffusion rate values of titanium, its compounds and alloys are summarized and tabulated. The individual chemical diffusion coefficients and self-diffusion coefficients of certain isotopes are given. Experimental methods are listed which were used for the determination of diffusion coefficients. Some values have been taken over from other studies. Also given are graphs showing the temperature dependences of diffusion and changes in the diffusion coefficient with concentration changes

  3. Novel Diffusion-Weighted MRI for High-Grade Prostate Cancer Detection

    Science.gov (United States)

    2017-10-01

    technical difficulty with comparison of radical prostatectomy histology with imaging, we have also introduced a method to evaluate the accuracy of our...MatLab code for co-registration of digital radical prostatectomy histology to T2 weighted MRI images of alpha and DDC maps to T2 weighted MRI was...HPA 479 ( Evaluation of Clinical Interventions), with a grade of A. He completed BHIS 509 (Informatics for the Clinical Investigator) with a grade

  4. Chronotype Modulates Language Processing-Related Cerebral Activity during Functional MRI (fMRI.

    Directory of Open Access Journals (Sweden)

    Jessica Rosenberg

    Full Text Available Based on individual daily physiological cycles, humans can be classified as early (EC, late (LC and intermediate (IC chronotypes. Recent studies have verified that chronotype-specificity relates to performance on cognitive tasks: participants perform more efficiently when tested in the chronotype-specific optimal time of day than when tested in their non-optimal time. Surprisingly, imaging studies focussing on the underlying neural mechanisms of potential chronotype-specificities are sparse. Moreover, chronotype-specific alterations of language-related semantic processing have been neglected so far.16 male, healthy ECs, 16 ICs and 16 LCs participated in a fast event-related functional Magnetic Resonance Imaging (fMRI paradigm probing semantic priming. Subjects read two subsequently presented words (prime, target and were requested to determine whether the target word was an existing word or a non-word. Subjects were tested during their individual evening hours when homeostatic sleep pressure and circadian alertness levels are high to ensure equal entrainment.Chronotype-specificity is associated with task-performance and brain activation. First, ECs exhibited slower reaction times than LCs. Second, ECs showed attenuated BOLD responses in several language-related brain areas, e.g. in the left postcentral gyrus, left and right precentral gyrus and in the right superior frontal gyrus. Additionally, increased BOLD responses were revealed for LCs as compared to ICs in task-related areas, e.g. in the right inferior parietal lobule and in the right postcentral gyrus.These findings reveal that even basic language processes are associated with chronotype-specific neuronal mechanisms. Consequently, results might change the way we schedule patient evaluations and/or healthy subjects in e.g. experimental research and adding "chronotype" as a statistical covariate.

  5. The role of isotropic diffusion MRI in children under 2 years of age

    International Nuclear Information System (INIS)

    Gelal, F.M.; Grant, P.E.; Fischbein, N.J.; Henry, R.G.; Vigneron, D.B.; Barkovich, A.J.

    2001-01-01

    Our objective was to determine the contribution of diffusion MR imaging to standard MR imaging in the neuroradiological evaluation of children less than 2 years of age. Echo-planar diffusion MR imaging was added to standard MR exams in 75 consecutive patients under the age of 2 years. Single-shot echo-planar spin-echo T2 weighted images (EPSE-T2) were acquired. Isotropic diffusion-weighted images (DWI), attenuation coefficient maps (ACM), and apparent diffusion coefficient (ADC) maps were calculated offline from images obtained with diffusion gradients (b=1000 s/mm 2 ) in three orthogonal directions. Two neuroradiologists determined if EPSE-T2, DWI, or ACM contributed new information to spin-echo proton density (SE PD) and T2 studies. In 15 of 18 abnormalities detected in 8 patients with symptoms less than 1 week in duration, DWI and/or ACM added information to SE PD and T2. Diffusion sequences detected five new lesions, showed six lesions with greater conspicuity, and identified four lesions with different diffusion character. In patients with symptoms of more than 7 days duration, diffusion studies added no information. Isotropic diffusion MR contributed to lesion detection and characterization in infants when symptoms were less than 1 week in duration. Diffusion MR is useful in patients with leukodystrophies, metabolic disorders, and patients with acute ischemic lesions. (orig.)

  6. Comparison of Diffusion MRI Acquisition Protocols for the In Vivo Characterization of the Mouse Spinal Cord: Variability Analysis and Application to an Amyotrophic Lateral Sclerosis Model.

    Science.gov (United States)

    Figini, Matteo; Scotti, Alessandro; Marcuzzo, Stefania; Bonanno, Silvia; Padelli, Francesco; Moreno-Manzano, Victoria; García-Verdugo, José Manuel; Bernasconi, Pia; Mantegazza, Renato; Bruzzone, Maria Grazia; Zucca, Ileana

    2016-01-01

    Diffusion-weighted Magnetic Resonance Imaging (dMRI) has relevant applications in the microstructural characterization of the spinal cord, especially in neurodegenerative diseases. Animal models have a pivotal role in the study of such diseases; however, in vivo spinal dMRI of small animals entails additional challenges that require a systematical investigation of acquisition parameters. The purpose of this study is to compare three acquisition protocols and identify the scanning parameters allowing a robust estimation of the main diffusion quantities and a good sensitivity to neurodegeneration in the mouse spinal cord. For all the protocols, the signal-to-noise and contrast-to noise ratios and the mean value and variability of Diffusion Tensor metrics were evaluated in healthy controls. For the estimation of fractional anisotropy less variability was provided by protocols with more diffusion directions, for the estimation of mean, axial and radial diffusivity by protocols with fewer diffusion directions and higher diffusion weighting. Intermediate features (12 directions, b = 1200 s/mm2) provided the overall minimum inter- and intra-subject variability in most cases. In order to test the diagnostic sensitivity of the protocols, 7 G93A-SOD1 mice (model of amyotrophic lateral sclerosis) at 10 and 17 weeks of age were scanned and the derived diffusion parameters compared with those estimated in age-matched healthy animals. The protocols with an intermediate or high number of diffusion directions provided the best differentiation between the two groups at week 17, whereas only few local significant differences were highlighted at week 10. According to our results, a dMRI protocol with an intermediate number of diffusion gradient directions and a relatively high diffusion weighting is optimal for spinal cord imaging. Further work is needed to confirm these results and for a finer tuning of acquisition parameters. Nevertheless, our findings could be important for the

  7. Quantification of diffusion tensor imaging in normal white matter maturation of early childhood using an automated processing pipeline.

    Science.gov (United States)

    Loh, K B; Ramli, N; Tan, L K; Roziah, M; Rahmat, K; Ariffin, H

    2012-07-01

    The degree and status of white matter myelination can be sensitively monitored using diffusion tensor imaging (DTI). This study looks at the measurement of fractional anistropy (FA) and mean diffusivity (MD) using an automated ROI with an existing DTI atlas. Anatomical MRI and structural DTI were performed cross-sectionally on 26 normal children (newborn to 48 months old), using 1.5-T MRI. The automated processing pipeline was implemented to convert diffusion-weighted images into the NIfTI format. DTI-TK software was used to register the processed images to the ICBM DTI-81 atlas, while AFNI software was used for automated atlas-based volumes of interest (VOIs) and statistical value extraction. DTI exhibited consistent grey-white matter contrast. Triphasic temporal variation of the FA and MD values was noted, with FA increasing and MD decreasing rapidly early in the first 12 months. The second phase lasted 12-24 months during which the rate of FA and MD changes was reduced. After 24 months, the FA and MD values plateaued. DTI is a superior technique to conventional MR imaging in depicting WM maturation. The use of the automated processing pipeline provides a reliable environment for quantitative analysis of high-throughput DTI data. Diffusion tensor imaging outperforms conventional MRI in depicting white matter maturation. • DTI will become an important clinical tool for diagnosing paediatric neurological diseases. • DTI appears especially helpful for developmental abnormalities, tumours and white matter disease. • An automated processing pipeline assists quantitative analysis of high throughput DTI data.

  8. The role of diffusion-weighted MRI (DWI) in the differentiation of benign from malignant skeletal lesions of the pelvis

    International Nuclear Information System (INIS)

    Douis, Hassan; Davies, Mark A.; Sian, Parmjit

    2016-01-01

    Purpose: To evaluate the utility of Diffusion-weighted MRI in the differentiation of benign from malignant skeletal lesions of the pelvis. Materials and methods: In this retrospective study 33 patients with indeterminate skeletal lesions of the pelvis were evaluated with DWI. Minimum, mean, maximum ADC-values of the skeletal lesions were measured followed by qualitative assessment of DWI. All patients underwent histological confirmation using CT-guided biopsy or surgical resection. The histology of the skeletal lesions was correlated with the findings on DWI. Results: There were 13 malignant lesions and 20 benign lesions. The mean, minimum and maximum ADC values (×10–6mm2/s) for benign skeletal lesions was higher than the mean ADC-values for malignant lesions (1422.2 vs 1263.7; 780.4 vs 771.8; 1969.6 vs 1676.8 respectively). These differences were however not statistically significant (P-values = 0.29; 0.94; 0.149 respectively). The sensitivity, specificity, positive predictive value and negative predictive value for qualitative assessment of Diffusion-weighted MRI in the differentiation of benign from malignant skeletal lesions were: 53.9%, 85%, 70%, 73.9% respectively. Qualitative assessment of DWI (restricted diffusion versus non-restricted diffusion) allowed differentiation of benign from malignant skeletal lesions (P-value = 0.0259). Conclusions: Qualitative assessment of DWI may aid in the differentiation of benign skeletal lesions from malignant skeletal lesions of the pelvis. Although DWI has a low sensitivity in the distinction of the two disease entities, it may be a useful adjunct due to its relatively high specificity. This is of particular importance in lymphoma where biopsy may only show chronic inflammatory cells and hence may be false negative.

  9. The role of diffusion-weighted MRI (DWI) in the differentiation of benign from malignant skeletal lesions of the pelvis

    Energy Technology Data Exchange (ETDEWEB)

    Douis, Hassan, E-mail: douis.hassan@hotmail.co.uk [Department of Radiology, University Hospital Birmingham NHS Foundation Trust, Birmingham, B15 2GW (United Kingdom); Department of Radiology, Royal Orthopaedic Hospital NHS Foundation Trust, Birmingham, B31 2AP (United Kingdom); Davies, Mark A. [Department of Radiology, Royal Orthopaedic Hospital NHS Foundation Trust, Birmingham, B31 2AP (United Kingdom); Sian, Parmjit [Department of Spinal Surgical Oncology, Royal Orthopaedic Hospital NHS Foundation Trust, Birmingham, B31 2AP (United Kingdom)

    2016-12-15

    Purpose: To evaluate the utility of Diffusion-weighted MRI in the differentiation of benign from malignant skeletal lesions of the pelvis. Materials and methods: In this retrospective study 33 patients with indeterminate skeletal lesions of the pelvis were evaluated with DWI. Minimum, mean, maximum ADC-values of the skeletal lesions were measured followed by qualitative assessment of DWI. All patients underwent histological confirmation using CT-guided biopsy or surgical resection. The histology of the skeletal lesions was correlated with the findings on DWI. Results: There were 13 malignant lesions and 20 benign lesions. The mean, minimum and maximum ADC values (×10–6mm2/s) for benign skeletal lesions was higher than the mean ADC-values for malignant lesions (1422.2 vs 1263.7; 780.4 vs 771.8; 1969.6 vs 1676.8 respectively). These differences were however not statistically significant (P-values = 0.29; 0.94; 0.149 respectively). The sensitivity, specificity, positive predictive value and negative predictive value for qualitative assessment of Diffusion-weighted MRI in the differentiation of benign from malignant skeletal lesions were: 53.9%, 85%, 70%, 73.9% respectively. Qualitative assessment of DWI (restricted diffusion versus non-restricted diffusion) allowed differentiation of benign from malignant skeletal lesions (P-value = 0.0259). Conclusions: Qualitative assessment of DWI may aid in the differentiation of benign skeletal lesions from malignant skeletal lesions of the pelvis. Although DWI has a low sensitivity in the distinction of the two disease entities, it may be a useful adjunct due to its relatively high specificity. This is of particular importance in lymphoma where biopsy may only show chronic inflammatory cells and hence may be false negative.

  10. Grading and outcome prediction of pediatric diffuse astrocytic tumors with diffusion and arterial spin labeling perfusion MRI in comparison with 18F-DOPA PET

    Energy Technology Data Exchange (ETDEWEB)

    Morana, Giovanni; Tortora, Domenico; Severino, Mariasavina; Rossi, Andrea [Istituto Giannina Gaslini, Neuroradiology Unit, Genoa (Italy); Piccardo, Arnoldo; Cabria, Manlio [Ente Ospedaliero Ospedali Galliera, Nuclear Medicine Unit, Genoa (Italy); Puntoni, Matteo [Ente Ospedaliero Ospedali Galliera, Clinical Trial Unit, Scientific Directorate, Genoa (Italy); Nozza, Paolo [Istituto Giannina Gaslini, Pathology Unit, Genoa (Italy); Ravegnani, Marcello; Consales, Alessandro; Mascelli, Samantha; Raso, Alessandro [Istituto Giannina Gaslini, Neurosurgery Unit, Genoa (Italy); Verrico, Antonio; Milanaccio, Claudia [Istituto Giannina Gaslini, Neuro-oncology Unit, Genoa (Italy)

    2017-11-15

    The aim of this study was to investigate MRI-derived diffusion weighted imaging (DWI) and arterial spin labeling (ASL) perfusion imaging in comparison with {sup 18}F-dihydroxyphenylalanine (DOPA) PET with respect to diagnostic performance in tumor grading and outcome prediction in pediatric patients with diffuse astrocytic tumors (DAT). We retrospectively analyzed 26 children with histologically proven treatment naive low and high grade DAT who underwent ASL and DWI performed within 2 weeks of {sup 18}F-DOPA PET. Relative ASL-derived cerebral blood flow max (rCBF max) and DWI-derived minimum apparent diffusion coefficient (rADC min) were compared with {sup 18}F-DOPA uptake tumor/normal tissue (T/N) and tumor/striatum (T/S) ratios, and correlated with World Health Organization (WHO) tumor grade and progression-free survival (PFS). Statistics included Pearson's chi-square and Mann-Whitney U tests, Spearman's rank correlation, receiver operating characteristic (ROC) analysis, discriminant function analysis (DFA), Kaplan-Meier survival curve, and Cox analysis. A significant correlation was demonstrated between rCBF max, rADC min, and {sup 18}F-DOPA PET data (p < 0.001). Significant differences in terms of rCBF max, rADC min, and {sup 18}F-DOPA uptake were found between low- and high-grade DAT (p ≤ 0.001). ROC analysis and DFA demonstrated that T/S and T/N values were the best parameters for predicting tumor progression (AUC 0.93, p < 0.001). On univariate analysis, all diagnostic tools correlated with PFS (p ≤ 0.001); however, on multivariate analysis, only {sup 18}F-DOPA uptake remained significantly associated with outcome (p ≤ 0.03), while a trend emerged for rCBF max (p = 0.09) and rADC min (p = 0.08). The combination of MRI and PET data increased the predictive power for prognosticating tumor progression (AUC 0.97, p < 0.001). DWI, ASL and {sup 18}F-DOPA PET provide useful complementary information for pediatric DAT grading. {sup 18}F-DOPA uptake

  11. Comparative study of diffusion weighted imaging and dynamic contrast enhanced MRI for the detection of small breast cancers

    International Nuclear Information System (INIS)

    Tang Jianhua; Yan Fuhua; Zhou Meiling; Ye Fang; Xu Pengju

    2008-01-01

    Objective: To compare the sensitivity of diffusion weighted imaging (DWI) with dynamic contrast enhanced (DCE) MRI for the detection of small breast cancers and to evaluate the clinical value of DWI. Methods: Forty-eight patients with benign (n=25) and malignant (n=45) small breast lesions (≤2 cm) proved by pathology underwent DWI and DCE MRI. The DCE MRI was performed using FLASH sequence and the time-signal intensity curve was drawn. The DWI was performed using GRAPPA- EPI sequence with different b values (800, 1000 s/mm 2 ) and the ADC values of lesions were measured. The sensitivity and specificity of DWI for the detection of small breast cancers were compared with DCE MRI. Results: Forty of 45 small breast cancers and 19 of 25 small benign breast lesions were correctly diagnosed using DCE MRI. The sensitivity and positive predictive value of TIC were 88.9% (40/45) and 87.0% (40/46). With b values of 800 s/mm 2 and 1000 s/mm 2 , the average ADC values of small breast cancers were (1.153±0.192) x 10 -3 and (1.079±0.186) x 10 -3 mm 2 /s, while those of benign ones were (1.473±0.252) x 10 -3 and (1.419 ± 0.255) x 10 -3 mm 2 /s, respectively. There was no significant difference for the ADC values with different b values in the same group (P>0.05), while there was a significant difference between the malignant and the benign lesions (P 2 . Both the sensitivity and positive predictive value of diagnosis were 86.7% (39/45). The abilities of DWI and DCE MRI for the diagnosis of small breast cancers were the same. The sensitivity (93.3%) and positive predictive value (91.3%) were improved with the combination of DCE MRI and DWI. Conclusion: DWI has a high sensitivity for the detection of small breast cancers, the ADC value can provide valuable information in the differential diagnosis. (authors)

  12. Diffusion-weighted imaging and dynamic contrast-enhanced MRI of experimental breast cancer bone metastases – A correlation study with histology

    Energy Technology Data Exchange (ETDEWEB)

    Merz, Maximilian [Department of Medical Physics in Radiology, German Cancer Research Center, Im Neuenheimer Feld 280, 69120 Heidelberg (Germany); Department of Hematology, Oncology and Rheumatology, Heidelberg University Hospital, Im Neuenheimer Feld 410, 69120 Heidelberg (Germany); Seyler, Lisa; Bretschi, Maren; Semmler, Wolfhard [Department of Medical Physics in Radiology, German Cancer Research Center, Im Neuenheimer Feld 280, 69120 Heidelberg (Germany); Bäuerle, Tobias, E-mail: tobias.baeuerle@uk-erlangen.de [Department of Medical Physics in Radiology, German Cancer Research Center, Im Neuenheimer Feld 280, 69120 Heidelberg (Germany); Institute of Radiology, University Medical Center Erlangen, Palmsanlage 5, 90154 Erlangen (Germany)

    2015-04-15

    Purpose: To validate imaging parameters from diffusion-weighted imaging and dynamic contrast-enhanced MRI with immunohistology and to non-invasively assess microstructure of experimental breast cancer bone metastases. Materials and methods: Animals bearing breast cancer bone metastases were imaged in a clinical 1.5 T MRI scanner. HASTE sequences were performed to calculate apparent diffusion coefficients. Saturation recovery turbo FLASH sequences were conducted while infusing 0.1 mmol/l Gd–DTPA for dynamic contrast-enhanced MRI to quantify parameters amplitude A and exchange rate constant k{sub ep}. After imaging, bone metastases were analyzed immunohistologically. Results: We found correlations of the apparent diffusion coefficients from diffusion-weighted imaging with tumor cellularity as assessed with cell nuclei staining. Histological vessel maturity was correlated negatively with parameters A and k{sub ep} from dynamic contrast-enhanced MRI. Tumor size correlated inversely with cell density and vessel permeability as well as positively with mean vessel calibers. Parameters from the rim of bone metastases differed significantly from values of the center. Conclusion: In vivo diffusion-weighted imaging and dynamic contrast-enhanced MRI in experimental bone metastases provide information about tumor cellularity and vascularity and correlate well with immunohistology.

  13. Individual differences in emotion word processing: A diffusion model analysis.

    Science.gov (United States)

    Mueller, Christina J; Kuchinke, Lars

    2016-06-01

    The exploratory study investigated individual differences in implicit processing of emotional words in a lexical decision task. A processing advantage for positive words was observed, and differences between happy and fear-related words in response times were predicted by individual differences in specific variables of emotion processing: Whereas more pronounced goal-directed behavior was related to a specific slowdown in processing of fear-related words, the rate of spontaneous eye blinks (indexing brain dopamine levels) was associated with a processing advantage of happy words. Estimating diffusion model parameters revealed that the drift rate (rate of information accumulation) captures unique variance of processing differences between happy and fear-related words, with highest drift rates observed for happy words. Overall emotion recognition ability predicted individual differences in drift rates between happy and fear-related words. The findings emphasize that a significant amount of variance in emotion processing is explained by individual differences in behavioral data.

  14. Rapid resolution of diffusion weighted MRI abnormality in a patient with a stuttering stroke

    Science.gov (United States)

    Peters, Jurriaan M; MacLean, Ainsley V; Young, Geoffrey S

    2010-01-01

    We report the unusually rapid and spontaneous normalisation of low diffusivity that accompanied resolution of acute neurological deficits in a stroke patient who underwent two magnetic resonance imaging examinations within 24 h of symptom onset. Diffusion weighted imaging obtained within hours of onset of left sided weakness demonstrated a focal right capsular area of low diffusivity that resolved within 24 h, coinciding with resolution of the patient’s symptoms. PMID:22315635

  15. Dynamics Of Innovation Diffusion With Two Step Decision Process

    Directory of Open Access Journals (Sweden)

    Szymczyk Michał

    2014-02-01

    Full Text Available The paper discusses the dynamics of innovation diffusion among heterogeneous consumers. We assume that customers’ decision making process is divided into two steps: testing the innovation and later potential adopting. Such a model setup is designed to imitate the mobile applications market. An innovation provider, to some extent, can control the innovation diffusion by two parameters: product quality and marketing activity. Using the multi-agent approach we identify factors influencing the saturation level and the speed of innovation adaptation in the artificial population. The results show that the expected level of innovation adoption among customer’s friends and relative product quality and marketing campaign intensity are crucial factors explaining them. It has to be stressed that the product quality is more important for innovation saturation level and marketing campaign has bigger influence on the speed of diffusion. The topology of social network between customers is found important, but within investigated parameter range it has lover impact on innovation diffusion dynamics than the above mentioned factors

  16. External boundary effects on simultaneous diffusion and reaction processes

    International Nuclear Information System (INIS)

    Le Roux, M.N.; Wilhelmsson, H.

    1989-01-01

    External boundaries influence the spatial and temporal structure of evolution of dynamic systems governed by reaction-diffusion equations. Critical limits, i.e. thresholds for explosive growth or onset of diffusion dominated decay, are found to be caused by the presence of the boundary and to depend on: the position of the boundary, where the density is assumed to be zero at any instant of time: the mutual weights (coefficients) and powers of the nonlinear reaction and diffusion processes; and the initial spatial distribution. However, for particular relations between the nonlinear powers of the reaction and diffusion terms the critical limits do not depend on the initial conditions. The results are obtained by simulation experiment for one, two and three dimensions. Trends in the dynamic evolution of the system with an external boundary imposed are compared with the corresponding analytic results obtained for free boundary. Interesting applications are found in various areas, e.g. in the field of high temperature fusion plasma where the evolution of the temperature profile for the so-called H-mode (constant plasma density) is described

  17. Microstructural changes in ischemic cortical gray matter predicted by a model of diffusion-weighted MRI.

    Science.gov (United States)

    Vestergaard-Poulsen, Peter; Hansen, Brian; Ostergaard, Leif; Jakobsen, Rikke

    2007-09-01

    To understand the diffusion attenuated MR signal from normal and ischemic brain tissue in order to extract structural and physiological information using mathematical modeling, taking into account the transverse relaxation rates in gray matter. We fit our diffusion model to the diffusion-weighted MR signal obtained from cortical gray matter in healthy subjects. Our model includes variable volume fractions, intracellular restriction effects, and exchange between compartments in addition to individual diffusion coefficients and transverse relaxation rates for each compartment. A global optimum was found from a wide range of parameter permutations using cluster computing. We also present simulations of cell swelling and changes of exchange rate and intracellular diffusion as possible cellular mechanisms in ischemia. Our model estimates an extracellular volume fraction of 0.19 in accordance with the accepted value from histology. The absolute apparent diffusion coefficient obtained from the model was similar to that of experiments. The model and the experimental results indicate significant differences in diffusion and transverse relaxation between the tissue compartments and slow water exchange. Our model reproduces the signal changes observed in ischemia via physiologically credible mechanisms. Our modeling suggests that transverse relaxation has a profound influence on the diffusion attenuated MR signal. Our simulations indicate cell swelling as the primary cause of the diffusion changes seen in the acute phase of brain ischemia. (c) 2007 Wiley-Liss, Inc.

  18. Diffusion tensor MRI and fiber tractography of the sacral plexus in children with spina bifida

    DEFF Research Database (Denmark)

    Haakma, Wieke; Dik, Pieter; ten Haken, Bennie

    2014-01-01

    anatomical and microstructural properties of the sacral plexus of patients with spina bifida using diffusion tensor imaging and fiber tractography. MATERIALS AND METHODS: Ten patients 8 to 16 years old with spina bifida underwent diffusion tensor imaging on a 3 Tesla magnetic resonance imaging system...... diffusivity values at S1-S3 were significantly lower in patients. CONCLUSIONS: To our knowledge this 3 Tesla magnetic resonance imaging study showed for the first time sacral plexus asymmetry and disorganization in 10 patients with spina bifida using diffusion tensor imaging and fiber tractography...

  19. MRI in seven cases of tacrolimus (FK-506) encephalopathy: utility of FLAIR and diffusion-weighted imaging

    Energy Technology Data Exchange (ETDEWEB)

    Furukawa, M. [Dept. of Radiology, Yamaguchi University School of Medicine, Ube (Japan); Dept. of Radiology, Hokkaido University School of Medicine, Sapporo (Japan); Terae, S.; Chu, B.C.; Kaneko, K.; Kamada, H.; Miyasaka, K. [Dept. of Radiology, Hokkaido University School of Medicine, Sapporo (Japan)

    2001-08-01

    We assessed the utility of fluid-attenuated inversion-recovery (FLAIR) and diffusion-weighted (DWI) images in investigation of tacrolimus (FK-506) encephalopathy, and to see whether we could predict its cause from clinical and imaging data. In seven patients with presumed FK-506 toxicity the areas involved on MRI were similar to those in cyclosporin A (CsA) toxicity. The abnormal signal was most evident on FLAIR in all cases. In three of four patients who underwent DWI, no diffusion abnormalities were detected; in the remaining patient, increased diffusion was seen in the deep white matter bilaterally on the apparent diffusion coefficient map, consistent with the findings on T2-weighted spin-echo and FLAIR images. Five of the six patients for whom we had clinical data showed sudden changes in electrolyte or fluid equilibrium due to diarrhoea, a polyuria or oliguria one day before or on the day of onset of the central nervous system disturbances. We speculate that FK-506 encephalopathy is triggered by the disturbance of the electrolyte and/or fluid equilibrium, given a certain serum level of FK-506. (orig.)

  20. MRI in seven cases of tacrolimus (FK-506) encephalopathy: utility of FLAIR and diffusion-weighted imaging

    International Nuclear Information System (INIS)

    Furukawa, M.; Terae, S.; Chu, B.C.; Kaneko, K.; Kamada, H.; Miyasaka, K.

    2001-01-01

    We assessed the utility of fluid-attenuated inversion-recovery (FLAIR) and diffusion-weighted (DWI) images in investigation of tacrolimus (FK-506) encephalopathy, and to see whether we could predict its cause from clinical and imaging data. In seven patients with presumed FK-506 toxicity the areas involved on MRI were similar to those in cyclosporin A (CsA) toxicity. The abnormal signal was most evident on FLAIR in all cases. In three of four patients who underwent DWI, no diffusion abnormalities were detected; in the remaining patient, increased diffusion was seen in the deep white matter bilaterally on the apparent diffusion coefficient map, consistent with the findings on T2-weighted spin-echo and FLAIR images. Five of the six patients for whom we had clinical data showed sudden changes in electrolyte or fluid equilibrium due to diarrhoea, a polyuria or oliguria one day before or on the day of onset of the central nervous system disturbances. We speculate that FK-506 encephalopathy is triggered by the disturbance of the electrolyte and/or fluid equilibrium, given a certain serum level of FK-506. (orig.)

  1. Holographic diffuser by use of a silver halide sensitized gelatin process

    Science.gov (United States)

    Kim, Sun Il; Choi, Yoon Sun; Ham, Yong Nam; Park, Chong Yun; Kim, Jong Man

    2003-05-01

    Diffusers play an important role in liquid-crystal display (LCD) application as a beam-shaping device, a brightness homogenizer, a light-scattering device, and an imaging screen. The transmittance and diffusing angle of the diffusers are the critical aspects for the applications to the LCD. The holographic diffusers by use of various processing methods have been investigated. The diffusing characteristics of different diffusing materials and processing methods have been evaluated and compared. The micro-structures of holographic diffusers have been investigated by use of using scanning electron microscopy. The holographic diffusers by use of the silver halide sensitized gelatin (SHSG) method have the structural merits for the improvement of the quality of diffusers. The features of holographic diffuser were exceptional in terms of transmittance and diffusing angle. The replication method by use of the SHSG process can be directly used for the manufacturing of diffusers for the display application.

  2. Diffusion processes in tumors: A nuclear medicine approach

    International Nuclear Information System (INIS)

    Amaya, Helman

    2016-01-01

    The number of counts used in nuclear medicine imaging techniques, only provides physical information about the desintegration of the nucleus present in the the radiotracer molecules that were uptaken in a particular anatomical region, but that information is not a real metabolic information. For this reason a mathematical method was used to find a correlation between number of counts and "1"8F-FDG mass concentration. This correlation allows a better interpretation of the results obtained in the study of diffusive processes in an agar phantom, and based on it, an image from the PETCETIX DICOM sample image set from OsiriX-viewer software was processed. PET-CT gradient magnitude and Laplacian images could show direct information on diffusive processes for radiopharmaceuticals that enter into the cells by simple diffusion. In the case of the radiopharmaceutical "1"8F-FDG is necessary to include pharmacokinetic models, to make a correct interpretation of the gradient magnitude and Laplacian of counts images.

  3. Diffusion processes in tumors: A nuclear medicine approach

    Energy Technology Data Exchange (ETDEWEB)

    Amaya, Helman, E-mail: haamayae@unal.edu.co [Grupo de Física Nuclear, Universidad Nacional de Colombia (Colombia)

    2016-07-07

    The number of counts used in nuclear medicine imaging techniques, only provides physical information about the desintegration of the nucleus present in the the radiotracer molecules that were uptaken in a particular anatomical region, but that information is not a real metabolic information. For this reason a mathematical method was used to find a correlation between number of counts and {sup 18}F-FDG mass concentration. This correlation allows a better interpretation of the results obtained in the study of diffusive processes in an agar phantom, and based on it, an image from the PETCETIX DICOM sample image set from OsiriX-viewer software was processed. PET-CT gradient magnitude and Laplacian images could show direct information on diffusive processes for radiopharmaceuticals that enter into the cells by simple diffusion. In the case of the radiopharmaceutical {sup 18}F-FDG is necessary to include pharmacokinetic models, to make a correct interpretation of the gradient magnitude and Laplacian of counts images.

  4. Clinical Implications of Diffuse Excessive High Signal Intensity (DEHSI on Neonatal MRI in School Age Children Born Extremely Preterm.

    Directory of Open Access Journals (Sweden)

    Lina Broström

    Full Text Available Magnetic resonance imaging (MRI of the brain carried out during the neonatal period shows that 55-80% of extremely preterm infants display white matter diffuse excessive high signal intensity (DEHSI. Our aim was to study differences in developmental outcome at the age of 6.5 years in children born extremely preterm with and without DEHSI.This was a prospective cohort study of 83 children who were born in Stockholm, Sweden, between 2004 and 2007, born at gestational age of < 27 weeks + 0 days and who underwent an MRI scan of their brain at term equivalent age. The outcome measures at 6.5 years included testing 66 children with the modified Touwen neurology examination, the Movement Assessment Battery for Children 2, the Wechsler Intelligence Scale for Children-Fourth Edition, Beery Visual-motor Integration test-Sixth Edition, and the Strengths and Difficulties Questionnaire. Group-wise comparisons were done between children with and without DEHSI using Student t-test, Mann Whitney U test, Chi square test and regression analysis.DEHSI was detected in 39 (59% of the 66 children who were assessed at 6.5 years. The presence of DEHSI was not associated with mild neurological dysfunction, scores on M-ABC assessment, cognition, visual-motor integration, or behavior at 6.5 years.The presence of qualitatively defined DEHSI on neonatal MRI did not prove to be a useful predictor of long-term impairment in children born extremely preterm.

  5. Redefining the target early during treatment. Can we visualize regional differences within the target volume using sequential diffusion weighted MRI?

    International Nuclear Information System (INIS)

    Lambrecht, Maarten; Van Herck, Hans; De Keyzer, Frederik; Vandecaveye, Vincent; Slagmolen, Pieter; Suetens, Paul; Hermans, Robert; Nuyts, Sandra

    2014-01-01

    Purpose: In head and neck cancer, diffusion weighted MRI (DWI) can predict response early during treatment. Treatment-induced changes and DWI-specific artifacts hinder an accurate registration between apparent diffusion coefficient (ADC) maps. The aim of the study was to develop a registration tool which calculates and visualizes regional changes in ADC. Methods: Twenty patients with stage IV HNC treated with primary radiotherapy received an MRI including DWI before and early during treatment. Markers were manually placed at anatomical landmarks on the different modalities at both time points. A registration method, consisting of a fully automatic rigid and nonrigid registration and two semi-automatic thin-plate spline (TPS) warps was developed and applied to the image sets. After each registration step the mean registration errors were calculated and ΔADC was compared between good and poor responders. Results: Adding the TPS warps significantly reduced the registration error (in mm, 6.3 ± 6.2 vs 3.2 ± 3.3 mm, p < 0.001). After the marker based registration the median ΔADC in poor responders was significantly lower than in good responders (7% vs. 21%; p < 0.001). Conclusions: This registration method allowed for a significant reduction of the mean registration error. Furthermore the voxel-wise calculation of the ΔADC early during radiotherapy allowed for a visualization of the regional differences of ΔADC within the tumor

  6. Pretreatment Diffusion-Weighted MRI Can Predict the Response to Neoadjuvant Chemotherapy in Patients with Nasopharyngeal Carcinoma

    Directory of Open Access Journals (Sweden)

    Guo-Yi Zhang

    2015-01-01

    Full Text Available Purpose. To explore the potential of diffusion-weighted (DW magnetic resonance imaging (MRI using apparent diffusion coefficient (ADC for predicting the response to neoadjuvant chemotherapy in nasopharyngeal carcinoma (NPC. Methods and Materials. Ninety-two consecutive patients with NPC who underwent three cycles of neoadjuvant chemotherapy were retrospectively analyzed. DW and anatomical MRI were performed before and after neoadjuvant chemotherapy prior to radiotherapy. Pretreatment ADCs and percentage increases in ADC after chemotherapy were calculated for the primary lesions and metastatic adenopathies. Receiver operating characteristic curve analysis was used to select optimal pretreatment ADCs. Results. Pretreatment mean ADCs were significantly lower for responders than for nonresponders (primary lesions, P=0.012; metastatic adenopathies, P=0.013. Mean percentage increases in ADC were higher for responders than for nonresponders (primary lesions, P=0.008; metastatic adenopathies, P<0.001. The optimal pretreatment primary lesion and metastatic adenopathy ADCs for differentiating responders from nonresponders were 0.897 × 10−3 mm2/sec and 1.031 × 10−3 mm2/sec, respectively. Conclusions. NPC patients with low pretreatment ADCs tend to respond better to neoadjuvant chemotherapy. Pretreatment ADCs could be used as a new pretreatment imaging biomarker of response to neoadjuvant chemotherapy.

  7. Role of diffusion-weighted echo-planar MRI in distinguishing between brain abscess and tumour: a preliminary report

    International Nuclear Information System (INIS)

    Noguchi, K.; Watanabe, N.; Nagayoshi, T.; Kanazawa, T.; Toyoshima, S.; Shimizu, M.; Seto, H.

    1999-01-01

    Our purpose was to evaluate diffusion-weighted (DW) echo-planar MRI in differentiating between brain abscess and tumour. We examined two patients with surgically confirmed pyogenic brain abscess and 18 with metastatic brain tumours or high-grade glioma, using a 1.5 T system. The apparent diffusion coefficient (ADC) of each necrotic or solid contrast-enhancing lesion was measured with two different b values (20 and 1200 s/mm 2 ). All capsule-stage brain abscesses (4 lesions) and zones of cerebritis (2 lesions) were identified on high-b-value DWI as markedly high-signal areas of decreased ADC (range, 0.58-0.70 [(10-3 mm 2 /s; mean, 0.63)]). All cystic or necrotic portions of brain tumours (14 lesions) were identified on high-b-value DWI as low-signal areas of increased ADC (range, 2.20-3.20 [(10-3 mm 2 /s; mean, 2.70)]). Solid, contrast-enhancing portions of brain tumours (19 lesions) were identified on high-b-value DWI as high-signal areas of sightly decreased or increased ADC (range, 0.77-1.29 [(10-3 mm 2 /s; mean, 0.94)]). Our preliminary results indicate that DW echo-planar MRI be used for distinguishing between brain abscess and tumour. (orig.) (orig.)

  8. Neonatal brain structure on MRI and diffusion tensor imaging, sex, and neurodevelopment in very-low-birthweight preterm children.

    Science.gov (United States)

    Rose, Jessica; Butler, Erin E; Lamont, Lauren E; Barnes, Patrick D; Atlas, Scott W; Stevenson, David K

    2009-07-01

    The neurological basis of an increased incidence of cerebral palsy (CP) in preterm males is unknown. This study examined neonatal brain structure on magnetic resonance imaging (MRI) and diffusion tensor imaging (DTI) at term-equivalent age, sex, and neurodevelopment at 1 year 6 months on the basis of the Amiel-Tison neurological examination, Gross Motor Function Classification System, and Bayley Scales of Infant Development in 78 very-low-birthweight preterm children (41 males, 37 females; mean gestational age 27.6 wks, SD 2.5; mean birthweight 1021 g, SD 339). Brain abnormalities on MRI and DTI were not different between males and females except in the splenium of the corpus callosum, where males had lower DTI fractional anisotropy (p=0.025) and a higher apparent diffusion coefficient (p=0.013), indicating delayed splenium development. In the 26 infants who were at higher risk on the basis of DTI, males had more abnormalities on MRI (p=0.034) and had lower fractional anisotropy and a higher apparent diffusion coefficient in the splenium (p=0.049; p=0.025) and right posterior limb of the internal capsule (PLIC; p=0.003; p=0.033). Abnormal neurodevelopment was more common in males (n=9) than in females (n=2; p=0.036). Children with abnormal neurodevelopment had more abnormalities on MRI (p=0.014) and reduced splenium and right PLIC fractional anisotropy (p=0.001; p=0.035). In children with abnormal neurodevelopment, right PLIC fractional anisotropy was lower than left (p=0.035), whereas in those with normal neurodevelopment right PLIC fractional anisotropy was higher than left (p=0.001). Right PLIC fractional anisotropy correlated to neurodevelopment (rho=0.371, p=0.002). Logistic regression predicted neurodevelopment with 94% accuracy; only right PLIC fractional anisotropy was a significant logistic coefficient. Results indicate that the higher incidence of abnormal neurodevelopment in preterm males relates to greater incidence and severity of brain abnormalities

  9. Assessment of treatment response by total tumor volume and global apparent diffusion coefficient using diffusion-weighted MRI in patients with metastatic bone disease: a feasibility study.

    Directory of Open Access Journals (Sweden)

    Matthew D Blackledge

    Full Text Available We describe our semi-automatic segmentation of whole-body diffusion-weighted MRI (WBDWI using a Markov random field (MRF model to derive tumor total diffusion volume (tDV and associated global apparent diffusion coefficient (gADC; and demonstrate the feasibility of using these indices for assessing tumor burden and response to treatment in patients with bone metastases. WBDWI was performed on eleven patients diagnosed with bone metastases from breast and prostate cancers before and after anti-cancer therapies. Semi-automatic segmentation incorporating a MRF model was performed in all patients below the C4 vertebra by an experienced radiologist with over eight years of clinical experience in body DWI. Changes in tDV and gADC distributions were compared with overall response determined by all imaging, tumor markers and clinical findings at serial follow up. The segmentation technique was possible in all patients although erroneous volumes of interest were generated in one patient because of poor fat suppression in the pelvis, requiring manual correction. Responding patients showed a larger increase in gADC (median change = +0.18, range = -0.07 to +0.78 × 10(-3 mm2/s after treatment compared to non-responding patients (median change = -0.02, range = -0.10 to +0.05 × 10(-3 mm2/s, p = 0.05, Mann-Whitney test, whereas non-responding patients showed a significantly larger increase in tDV (median change = +26%, range = +3 to +284% compared to responding patients (median change = -50%, range = -85 to +27%, p = 0.02, Mann-Whitney test. Semi-automatic segmentation of WBDWI is feasible for metastatic bone disease in this pilot cohort of 11 patients, and could be used to quantify tumor total diffusion volume and median global ADC for assessing response to treatment.

  10. Assessment of early renal allograft dysfunction with blood oxygenation level-dependent MRI and diffusion-weighted imaging

    Energy Technology Data Exchange (ETDEWEB)

    Park, Sung Yoon [Department of Radiology and Research Institute of Radiological Science, Severance Hospital, Yonsei University College of Medicine, Seoul (Korea, Republic of); Kim, Chan Kyo, E-mail: chankyokim@skku.edu [Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of); Park, Byung Kwan [Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of); Kim, Sung Ju; Lee, Sanghoon [Department of Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of); Huh, Wooseong [Department of Nephrology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul (Korea, Republic of)

    2014-12-15

    Highlights: • R2* and ADC in renal allografts are moderately correlated with eGFR. • R2* and ADC are lower in early allograft dysfunction than normal allograft function. • No significant difference between AR and ATN was found in both R2* and ADC. - Abstract: Purpose: To investigate blood oxygenation level-dependent (BOLD) MRI and diffusion-weighted imaging (DWI) at 3 T for assessment of early renal allograft dysfunction. Materials and methods: 34 patients with a renal allograft (early dysfunction, 24; normal, 10) were prospectively enrolled. BOLD MRI and DWI were performed at 3 T. R2* and apparent diffusion coefficient (ADC) values were measured in cortex and medulla of the allografts. Correlation between R2* or ADC values and estimated glomerular filtration rate (eGFR) was investigated. R2* or ADC values were compared among acute rejection (AR), acute tubular necrosis (ATN) and normal function. Results: In all renal allografts, cortical or medullary R2* and ADC values were moderately correlated with eGFR (P < 0.05). Early dysfunction group showed lower R2* and ADC values than normal function group (P < 0.05). AR or ATN had lower R2* values than normal allografts (P < 0.05), and ARs had lower cortical ADC values than normal allografts (P < 0.05). No significant difference of R2* or ADC values was found between AR and ATN (P > 0.05). Conclusion: BOLD MRI and DWI at 3 T may demonstrate early functional state of renal allografts, but may be limited in characterizing a cause of early renal allograft dysfunction. Further studies are needed.

  11. The functional relevance of diffusion tensor imaging in comparison to conventional MRI in patients with cervical compressive myelopathy

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Young-Mi; Oh, Jae-Keun; Song, Ji-Sun [Hallym University Sacred Heart Hospital, College of Medicine, Hallym University, Spine Center, Anyang-si, Gyeonggi-do (Korea, Republic of); Yoo, Woo-Kyoung [Hallym University Sacred Heart Hospital, College of Medicine, Hallym University, Department of Physical Medicine and Rehabilitation, Anyang-si (Korea, Republic of); Hallym University Sacred Heart Hospital, College of Medicine, Hallym University, Hallym Institute for Translational Genomics and Bioinformatics, Anyang-si (Korea, Republic of); Yoo, Je Hyun; Kwak, Yoon Hae [Hallym University Sacred Heart Hospital, College of Medicine, Hallym University, Department of Orthopaedic surgery, Anyang-si (Korea, Republic of); Kim, Seok Woo [Hallym University Sacred Heart Hospital, College of Medicine, Hallym University, Spine Center, Anyang-si, Gyeonggi-do (Korea, Republic of); Hallym University Sacred Heart Hospital, College of Medicine, Hallym University, Department of Orthopaedic surgery, Anyang-si (Korea, Republic of)

    2017-11-15

    To determine the functional relevance of diffusion tensor imaging (DTI) metrics and conventional MRI (signal intensity change in T2, compression ratio) by measuring the correlation of these parameters with clinical outcome measured by the modified Japanese Orthopedic Association (mJOA) score. A total of 20 cervical myelopathy (CM) patients participated in this prospective cohort study. The severities of CM were assessed using the mJOA score. Conventional MRIs (T2-weighted images) measuring the signal changes of spinal cords and the degree of compression at the lesion level and DTI metrics [fractional anisotropy (FA), apparent diffusion coefficient (ADC)] at each lesion and below each lesion (C7/T1) level were acquired using a 3-T Achieva MRI. These parameters were correlated with the mJOA scores to determine the functional relevance. Ninety percent of CM patients showed signal changes and 30 % of patients noted a more than 40% canal compression ratio in conventional MRIs at the lesion level; however, these findings were not correlated with the mJOA score (p < 0.05). In contrast, FA values on DTI showed high sensitivity to CM (100%), which was well correlated with the mJOA score (p = 0.034, r = 0.475) below the lesion level (C7/T1). This study showed a meaningful symptomatic correlation between mJOA scores and FA values below the lesion levels in CM patients. It could give us more understanding of the pathological changes in spinal cords matched with various clinical findings in CM patients than the results from conventional MRI. (orig.)

  12. Visualization of transverse diffusion paths across fiber cells of the ocular lens by small animal MRI

    International Nuclear Information System (INIS)

    Vaghefi, Ehsan; Hunter, Peter J; Jacobs, Marc D; Pontre, Beau; Donaldson, Paul J

    2009-01-01

    The sense of vision requires that light penetrate through the ocular lens. Experiments, performed and published by many research groups, have suggested that the lens, which has no blood vessels, relies on internally directed ion and water fluxes for its circulation, survival and transparency. We investigated the internal diffusive pathways of the lens in order to better understand the constraints that may be operating on directional lens fluxes. Small animal magnetic resonance imaging, including T2-weighted and diffusion tensor imaging, was used to measure tissue properties and diffusivity throughout cultured bovine lenses. A range of concentric regions of signal intensity was distinguished inside the lens, by both T2-weighted signal and mean diffusivity. Diffusivity mapping of the lens revealed novel anisotropic polar and equatorial zones of pronounced diffusivity directed transverse to the fiber cells. In contrast, an inner zone including the lens nucleus showed isotropic and weak diffusivity. Our results lend support to models of internally directed lens micro-circulation, by placing non-structural diffusive constraints on global patterns of fluid circulation

  13. Reviewing the process of preparing children for MRI

    Energy Technology Data Exchange (ETDEWEB)

    Hallowell, Leanne M.; Stewart, Shari E. [Royal Children' s Hospital, Department of Educational Play Therapy, Melbourne, Victoria (Australia); Amorim e.Silva, Cicero T. de [Royal Children' s Hospital, Department of Medical Imaging, Melbourne (Australia); King Faisal Specialist Hospital and Research Centre, Pediatric Radiology Section, Radiology Department, Riyadh (Saudi Arabia); Ditchfield, Michael R. [Royal Children' s Hospital, Department of Medical Imaging, Melbourne (Australia)

    2008-03-15

    MRI is a common medical imaging investigation. Patients, including young children, can be required to keep still for up to 60 min for the study to be completed successfully. Children often find the confined space, noise, need to lie still and possibility of intravenous administration of contrast agent anxiety-provoking and sometimes so distressing that they are unable to cope and require general anaesthesia. A practice MRI intervention was introduced at the Royal Children's Hospital in Melbourne, Australia. The program is conducted by educational play therapists in conjunction with the Department of Medical Imaging. This study explored the effectiveness of this intervention. The intervention was conducted in a practice MRI unit devoid of magnets. Data were collected as a clinical audit with respect to age, gender, times of scans, position in bore, diagnostic scans and movement artefact. Epidata and Stata were used to analyze the data. A total of 291 children were included; their ages ranged from 3 years 7 months to 17 years (mean 7.9 years), and 48.8% were male. Of the 291 children, 218 (74.9%) were considered a pass at practice, 35 (12 %) were considered borderline pass, and diagnostic images were obtained from 218 (96%) of those children who went onto a clinical MRI. We conclude that practice MRI intervention facilitated by educational play therapists is a useful intervention in supporting children to cope with MRI without general anaesthesia. (orig.)

  14. Reviewing the process of preparing children for MRI

    International Nuclear Information System (INIS)

    Hallowell, Leanne M.; Stewart, Shari E.; Amorim e Silva, Cicero T. de; Ditchfield, Michael R.

    2008-01-01

    MRI is a common medical imaging investigation. Patients, including young children, can be required to keep still for up to 60 min for the study to be completed successfully. Children often find the confined space, noise, need to lie still and possibility of intravenous administration of contrast agent anxiety-provoking and sometimes so distressing that they are unable to cope and require general anaesthesia. A practice MRI intervention was introduced at the Royal Children's Hospital in Melbourne, Australia. The program is conducted by educational play therapists in conjunction with the Department of Medical Imaging. This study explored the effectiveness of this intervention. The intervention was conducted in a practice MRI unit devoid of magnets. Data were collected as a clinical audit with respect to age, gender, times of scans, position in bore, diagnostic scans and movement artefact. Epidata and Stata were used to analyze the data. A total of 291 children were included; their ages ranged from 3 years 7 months to 17 years (mean 7.9 years), and 48.8% were male. Of the 291 children, 218 (74.9%) were considered a pass at practice, 35 (12 %) were considered borderline pass, and diagnostic images were obtained from 218 (96%) of those children who went onto a clinical MRI. We conclude that practice MRI intervention facilitated by educational play therapists is a useful intervention in supporting children to cope with MRI without general anaesthesia. (orig.)

  15. Time-Dependent Diffusion MRI in Cancer: Tissue Modeling and Applications

    Directory of Open Access Journals (Sweden)

    Olivier Reynaud

    2017-11-01

    Full Text Available In diffusion weighted imaging (DWI, the apparent diffusion coefficient (ADC has been recognized as a useful and sensitive surrogate for cell density, paving the way for non-invasive tumor staging, and characterization of treatment efficacy in cancer. However, microstructural parameters, such as cell size, density and/or compartmental diffusivities affect diffusion in various fashions, making of conventional DWI a sensitive but non-specific probe into changes happening at cellular level. Alternatively, tissue complexity can be probed and quantified using the time dependence of diffusion metrics, sometimes also referred to as temporal diffusion spectroscopy when only using oscillating diffusion gradients. Time-dependent diffusion (TDD is emerging as a strong candidate for specific and non-invasive tumor characterization. Despite the lack of a general analytical solution for all diffusion times/frequencies, TDD can be probed in various regimes where systems simplify in order to extract relevant information about tissue microstructure. The fundamentals of TDD are first reviewed (a in the short time regime, disentangling structural and diffusive tissue properties, and (b near the tortuosity limit, assuming weakly heterogeneous media near infinitely long diffusion times. Focusing on cell bodies (as opposed to neuronal tracts, a simple but realistic model for intracellular diffusion can offer precious insight on diffusion inside biological systems, at all times. Based on this approach, the main three geometrical models implemented so far (IMPULSED, POMACE, VERDICT are reviewed. Their suitability to quantify cell size, intra- and extracellular spaces (ICS and ECS and diffusivities are assessed. The proper modeling of tissue membrane permeability—hardly a newcomer in the field, but lacking applications—and its impact on microstructural estimates are also considered. After discussing general issues with tissue modeling and microstructural parameter

  16. Time-dependent diffusion MRI in cancer: tissue modeling and applications

    Science.gov (United States)

    Reynaud, Olivier

    2017-11-01

    In diffusion weighted imaging (DWI), the apparent diffusion coefficient has been recognized as a useful and sensitive surrogate for cell density, paving the way for non-invasive tumor staging, and characterization of treatment efficacy in cancer. However, microstructural parameters, such as cell size, density and/or compartmental diffusivities affect diffusion in various fashions, making of conventional DWI a sensitive but non-specific probe into changes happening at cellular level. Alternatively, tissue complexity can be probed and quantified using the time dependence of diffusion metrics, sometimes also referred to as temporal diffusion spectroscopy when only using oscillating diffusion gradients. Time-dependent diffusion (TDD) is emerging as a strong candidate for specific and non-invasive tumor characterization. Despite the lack of a general analytical solution for all diffusion times / frequencies, TDD can be probed in various regimes where systems simplify in order to extract relevant information about tissue microstructure. The fundamentals of TDD are first reviewed (a) in the short time regime, disentangling structural and diffusive tissue properties, and (b) near the tortuosity limit, assuming weakly heterogeneous media near infinitely long diffusion times. Focusing on cell bodies (as opposed to neuronal tracts), a simple but realistic model for intracellular diffusion can offer precious insight on diffusion inside biological systems, at all times. Based on this approach, the main three geometrical models implemented so far (IMPULSED, POMACE, VERDICT) are reviewed. Their suitability to quantify cell size, intra- and extracellular spaces (ICS and ECS) and diffusivities are assessed. The proper modeling of tissue membrane permeability – hardly a newcomer in the field, but lacking applications - and its impact on microstructural estimates are also considered. After discussing general issues with tissue modeling and microstructural parameter estimation (i

  17. Comparison of endorectal coil and nonendorectal coil T2W and diffusion-weighted MRI at 3 Tesla for localizing prostate cancer: correlation with whole-mount histopathology.

    Science.gov (United States)

    Turkbey, Baris; Merino, Maria J; Gallardo, Elma Carvajal; Shah, Vijay; Aras, Omer; Bernardo, Marcelino; Mena, Esther; Daar, Dagane; Rastinehad, Ardeshir R; Linehan, W Marston; Wood, Bradford J; Pinto, Peter A; Choyke, Peter L

    2014-06-01

    To compare utility of T2-weighted (T2W) MRI and diffusion-weighted MRI (DWI-MRI) obtained with and without an endorectal coil at 3 Tesla (T) for localizing prostate cancer. This Institutional Review Board-approved study included 20 patients (median prostate-specific antigen, 8.4 ng/mL). Patients underwent consecutive prostate MRIs at 3T, first with a surface coil alone, then with combination of surface, endorectal coils (dual coil) followed by robotic assisted radical prostatectomy. Lesions were mapped at time of acquisition on dual-coil T2W, DWI-MRI. To avoid bias, 6 months later nonendorectal coil T2W, DWI-MRI were mapped. Both MRI evaluations were performed by two readers blinded to pathology with differences resolved by consensus. A lesion-based correlation with whole-mount histopathology was performed. At histopathology 51 cancer foci were present ranging in size from 2 to 60 mm. The sensitivity of the endorectal dual-coil, nonendorectal coil MRIs were 0.76, 0.45, respectively. PPVs for endorectal dual-coil, nonendorectal coil MRI were 0.80, 0.64, respectively. Mean size of detected lesions with nonendorectal coil MRI were larger than those detected by dual-coil MRI (22 mm versus 17.4 mm). Dual-coil prostate MRI detected more cancer foci than nonendorectal coil MRI. While nonendorectal coil MRI is an attractive alternative, physicians performing prostate MRI should be aware of its limitations. Copyright © 2013 Wiley Periodicals, Inc.

  18. Network formation determined by the diffusion process of random walkers

    International Nuclear Information System (INIS)

    Ikeda, Nobutoshi

    2008-01-01

    We studied the diffusion process of random walkers in networks formed by their traces. This model considers the rise and fall of links determined by the frequency of transports of random walkers. In order to examine the relation between the formed network and the diffusion process, a situation in which multiple random walkers start from the same vertex is investigated. The difference in diffusion rate of random walkers according to the difference in dimension of the initial lattice is very important for determining the time evolution of the networks. For example, complete subgraphs can be formed on a one-dimensional lattice while a graph with a power-law vertex degree distribution is formed on a two-dimensional lattice. We derived some formulae for predicting network changes for the 1D case, such as the time evolution of the size of nearly complete subgraphs and conditions for their collapse. The networks formed on the 2D lattice are characterized by the existence of clusters of highly connected vertices and their life time. As the life time of such clusters tends to be small, the exponent of the power-law distribution changes from γ ≅ 1-2 to γ ≅ 3

  19. Nonstationary random acoustic and electromagnetic fields as wave diffusion processes

    International Nuclear Information System (INIS)

    Arnaut, L R

    2007-01-01

    We investigate the effects of relatively rapid variations of the boundaries of an overmoded cavity on the stochastic properties of its interior acoustic or electromagnetic field. For quasi-static variations, this field can be represented as an ideal incoherent and statistically homogeneous isotropic random scalar or vector field, respectively. A physical model is constructed showing that the field dynamics can be characterized as a generalized diffusion process. The Langevin-It o-hat and Fokker-Planck equations are derived and their associated statistics and distributions for the complex analytic field, its magnitude and energy density are computed. The energy diffusion parameter is found to be proportional to the square of the ratio of the standard deviation of the source field to the characteristic time constant of the dynamic process, but is independent of the initial energy density, to first order. The energy drift vanishes in the asymptotic limit. The time-energy probability distribution is in general not separable, as a result of nonstationarity. A general solution of the Fokker-Planck equation is obtained in integral form, together with explicit closed-form solutions for several asymptotic cases. The findings extend known results on statistics and distributions of quasi-stationary ideal random fields (pure diffusions), which are retrieved as special cases

  20. Dynamic Contrast Magnetic Resonance Imaging (DCE-MRI) and Diffusion Weighted MR Imaging (DWI) for Differentiation between Benign and Malignant Salivary Gland Tumors

    OpenAIRE

    Assili, S.; Fathi Kazerooni, A.; Aghaghazvini, L.; Saligheh Rad, H.R.; Pirayesh Islamian, J.

    2015-01-01

    Background: Salivary gland tumors form nearly 3% of head and neck tumors. Due to their large histological variety and vicinity to facial nerves, pre-operative diagnosis and differentiation of benign and malignant parotid tumors are a major challenge for radiologists. Objective: The majority of these tumors are benign; however, sometimes they tend to transform into a malignant form. Functional MRI techniques, namely dynamic contrast enhanced (DCE-) MRI and diffusion-weighted ...

  1. Diffusion processes in bombardment-induced surface topography

    International Nuclear Information System (INIS)

    Robinson, R.S.

    1984-01-01

    The bombardment of surfaces with moderate energy ions can lead to the development of various micron-sized surface structures. These structures include ridges, ledges, flat planes, pits and cones. The causal phenomena in the production of these features are sputtering, ion reflection, redeposition of sputtered material, and surface diffusion of both impurity and target-atom species. The authors concentrate on the formation of ion bombardment-induced surface topography wherein surface diffusion is a dominant process. The most thoroughly understood aspect of this topography development is the generation of cone-like structures during sputtering. The formation of cones during sputtering has been attributed to three effects. These are: (1) the presence of asperities, defects, or micro-inclusions in the surface layers, (2) the presence of impurities on the surfaces, and (3) particular crystal orientations. (Auth.)

  2. Modeling Effectivity of Atmospheric Advection-Diffusion Processes

    International Nuclear Information System (INIS)

    Brojewski, R.

    1999-01-01

    Some methods of solving the advection-diffusion problems useful in the field of atmospheric physics are presented and analyzed in the paper. The most effective one ( from the point of view of computer applications) was chosen. This is the method of problem decomposition with respect to the directions followed by secondary decomposition of the problem with respect to the physical phenomena. Introducing some corrections to the classical numerical methods of solving the problems, a hybrid composed of the finite element method for the advection problems and the implicit method with averaging for the diffusion processes was achieved. This hybrid method and application of the corrections produces a very effective means for solving the problems of substance transportation in atmosphere. (author)

  3. Diffusion measurement of intraplaque hemorrhage and intramural hematoma using diffusion weighted MRI at 3T in cervical artery

    Energy Technology Data Exchange (ETDEWEB)

    Yao, Bin [The Second Affiliated Hospital of Nanchang University, Nanchang, Jiangxi (China); Yang, Li [Fudan University, Department of Radiology, Shanghai Institute of Medical Imaging, Zhongshan Hospital, Shanghai (China); Wang, Guangbin; Shi, Honglu; Wang, Shanshan; Li, Huihua [Shandong University, Shandong Medical Imaging Research Institute, Jinan, Shandong (China); Chen, Weibo; Chan, Queenie [Philips Healthcare, Shanghai (China)

    2016-10-15

    To assess the difference between carotid haemorrhagic plaque and non-haemorrhagic plaque by using diffusion-weighted imaging (DWI) and to evaluate carotid intraplaque haemorrhage (IPH) and intramural hematoma (IMH) of cervical artery dissection with apparent diffusion coefficient (ADC) measurement. Fifty-one symptomatic patients underwent 3.0-T carotid MR imaging, including conventional sequences, three-dimensional (3D) magnetization-prepared rapid acquisition gradient-echo (MPRAGE) sequence, and DWI. Thirty-nine patients with carotid plaque and eight patients with IMH of cervical artery dissection were finally included. The groups of hemorrhagic plaque, non-hemorrhagic plaque and IMH were divided according to 3D MPRAGE sequence. ADC values of different groups were measured, and t tests were performed. The mean ADC values of hemorrhagic plaques, non-hemorrhagic plaque and IMH were (1.284 ± 0.327) x 10{sup -3}mm{sup 2}/s, (1.766 ± 0.477) x 10{sup -3}mm{sup 2}/s, and (0.563 ± 0.119) x 10{sup -3}mm{sup 2}/s, respectively. The mean ADC values of hemorrhagic and non-hemorrhagic regions in the hemorrhagic plaque group were (0.985 ± 0.376) x 10{sup -3}mm{sup 2}/s and (1.480 ± 0.465) x 10{sup -3}mm{sup 2}/s, respectively. The differences between the hemorrhagic plaque and non-hemorrhagic plaque, hemorrhagic region and non-hemorrhagic region in hemorrhagic plaque, and the hemorrhagic region in the hemorrhagic plaque and IMH of artery dissection were significant (P < 0.05). DWI may be a useful complement to conventional MR imaging for identifying haemorrhage of carotid plaques and differentiate IMHs from IPH. (orig.)

  4. Diffusion measurement of intraplaque hemorrhage and intramural hematoma using diffusion weighted MRI at 3T in cervical artery

    International Nuclear Information System (INIS)

    Yao, Bin; Yang, Li; Wang, Guangbin; Shi, Honglu; Wang, Shanshan; Li, Huihua; Chen, Weibo; Chan, Queenie

    2016-01-01

    To assess the difference between carotid haemorrhagic plaque and non-haemorrhagic plaque by using diffusion-weighted imaging (DWI) and to evaluate carotid intraplaque haemorrhage (IPH) and intramural hematoma (IMH) of cervical artery dissection with apparent diffusion coefficient (ADC) measurement. Fifty-one symptomatic patients underwent 3.0-T carotid MR imaging, including conventional sequences, three-dimensional (3D) magnetization-prepared rapid acquisition gradient-echo (MPRAGE) sequence, and DWI. Thirty-nine patients with carotid plaque and eight patients with IMH of cervical artery dissection were finally included. The groups of hemorrhagic plaque, non-hemorrhagic plaque and IMH were divided according to 3D MPRAGE sequence. ADC values of different groups were measured, and t tests were performed. The mean ADC values of hemorrhagic plaques, non-hemorrhagic plaque and IMH were (1.284 ± 0.327) x 10 -3 mm 2 /s, (1.766 ± 0.477) x 10 -3 mm 2 /s, and (0.563 ± 0.119) x 10 -3 mm 2 /s, respectively. The mean ADC values of hemorrhagic and non-hemorrhagic regions in the hemorrhagic plaque group were (0.985 ± 0.376) x 10 -3 mm 2 /s and (1.480 ± 0.465) x 10 -3 mm 2 /s, respectively. The differences between the hemorrhagic plaque and non-hemorrhagic plaque, hemorrhagic region and non-hemorrhagic region in hemorrhagic plaque, and the hemorrhagic region in the hemorrhagic plaque and IMH of artery dissection were significant (P < 0.05). DWI may be a useful complement to conventional MR imaging for identifying haemorrhage of carotid plaques and differentiate IMHs from IPH. (orig.)

  5. Gas phase decontamination of gaseous diffusion process equipment

    International Nuclear Information System (INIS)

    Bundy, R.D.; Munday, E.B.; Simmons, D.W.; Neiswander, D.W.

    1994-01-01

    D ampersand D of the process facilities at the gaseous diffusion plants (GDPs) will be an enormous task. The EBASCO estimate places the cost of D ampersand D of the GDP at the K-25 Site at approximately $7.5 billion. Of this sum, nearly $4 billion is associated with the construction and operation of decontamination facilities and the dismantlement and transport of contaminated process equipment to these facilities. In situ long-term low-temperature (LTLT) gas phase decontamination is being developed and demonstrated at the K-25 site as a technology that has the potential to substantially lower these costs while reducing criticality and safeguards concerns and worker exposure to hazardous and radioactive materials. The objective of gas phase decontamination is to employ a gaseous reagent to fluorinate nonvolatile uranium deposits to form volatile LJF6, which can be recovered by chemical trapping or freezing. The LTLT process permits the decontamination of the inside of gas-tight GDP process equipment at room temperature by substituting a long exposure to subatmospheric C1F for higher reaction rates at higher temperatures. This paper outlines the concept for applying LTLT gas phase decontamination, reports encouraging laboratory experiments, and presents the status of the design of a prototype mobile system. Plans for demonstrating the LTLT process on full-size gaseous diffusion equipment are also outlined briefly

  6. Quantification of diffusion tensor imaging in normal white matter maturation of early childhood using an automated processing pipeline

    International Nuclear Information System (INIS)

    Loh, K.B.; Ramli, N.; Tan, L.K.; Roziah, M.; Rahmat, K.; Ariffin, H.

    2012-01-01

    The degree and status of white matter myelination can be sensitively monitored using diffusion tensor imaging (DTI). This study looks at the measurement of fractional anistropy (FA) and mean diffusivity (MD) using an automated ROI with an existing DTI atlas. Anatomical MRI and structural DTI were performed cross-sectionally on 26 normal children (newborn to 48 months old), using 1.5-T MRI. The automated processing pipeline was implemented to convert diffusion-weighted images into the NIfTI format. DTI-TK software was used to register the processed images to the ICBM DTI-81 atlas, while AFNI software was used for automated atlas-based volumes of interest (VOIs) and statistical value extraction. DTI exhibited consistent grey-white matter contrast. Triphasic temporal variation of the FA and MD values was noted, with FA increasing and MD decreasing rapidly early in the first 12 months. The second phase lasted 12-24 months during which the rate of FA and MD changes was reduced. After 24 months, the FA and MD values plateaued. DTI is a superior technique to conventional MR imaging in depicting WM maturation. The use of the automated processing pipeline provides a reliable environment for quantitative analysis of high-throughput DTI data. (orig.)

  7. Quantification of diffusion tensor imaging in normal white matter maturation of early childhood using an automated processing pipeline

    Energy Technology Data Exchange (ETDEWEB)

    Loh, K.B.; Ramli, N.; Tan, L.K.; Roziah, M. [University of Malaya, Department of Biomedical Imaging, University Malaya Research Imaging Centre (UMRIC), Faculty of Medicine, Kuala Lumpur (Malaysia); Rahmat, K. [University of Malaya, Department of Biomedical Imaging, University Malaya Research Imaging Centre (UMRIC), Faculty of Medicine, Kuala Lumpur (Malaysia); University Malaya, Biomedical Imaging Department, Kuala Lumpur (Malaysia); Ariffin, H. [University of Malaya, Department of Paediatrics, Faculty of Medicine, Kuala Lumpur (Malaysia)

    2012-07-15

    The degree and status of white matter myelination can be sensitively monitored using diffusion tensor imaging (DTI). This study looks at the measurement of fractional anistropy (FA) and mean diffusivity (MD) using an automated ROI with an existing DTI atlas. Anatomical MRI and structural DTI were performed cross-sectionally on 26 normal children (newborn to 48 months old), using 1.5-T MRI. The automated processing pipeline was implemented to convert diffusion-weighted images into the NIfTI format. DTI-TK software was used to register the processed images to the ICBM DTI-81 atlas, while AFNI software was used for automated atlas-based volumes of interest (VOIs) and statistical value extraction. DTI exhibited consistent grey-white matter contrast. Triphasic temporal variation of the FA and MD values was noted, with FA increasing and MD decreasing rapidly early in the first 12 months. The second phase lasted 12-24 months during which the rate of FA and MD changes was reduced. After 24 months, the FA and MD values plateaued. DTI is a superior technique to conventional MR imaging in depicting WM maturation. The use of the automated processing pipeline provides a reliable environment for quantitative analysis of high-throughput DTI data. (orig.)

  8. Ultrasound elastography and diffusion weighted MRI in patients with rectal cancer

    DEFF Research Database (Denmark)

    Rafaelsen, Søren Rafael; Vagn-Hansen, Chris Aksel; Sørensen, Torben

    the Acoustic Radiation Force Impulse (ARFI) to generate information on the mechanical properties of the tissue. The objective quantitative elastography shear wave velocity was blindly compared to the ADC measurements using a 1.5 Tesla MRI system. The study was approved by the local Clinical Ethics Committee...

  9. Validation of diffusion tensor MRI measurements of cardiac microstructure with structure tensor synchrotron radiation imaging.

    Science.gov (United States)

    Teh, Irvin; McClymont, Darryl; Zdora, Marie-Christine; Whittington, Hannah J; Davidoiu, Valentina; Lee, Jack; Lygate, Craig A; Rau, Christoph; Zanette, Irene; Schneider, Jürgen E

    2017-03-10

    Diffusion tensor imaging (DTI) is widely used to assess tissue microstructure non-invasively. Cardiac DTI enables inference of cell and sheetlet orientations, which are altered under pathological conditions. However, DTI is affected by many factors, therefore robust validation is critical. Existing histological validation is intrinsically flawed, since it requires further tissue processing leading to sample distortion, is routinely limited in field-of-view and requires reconstruction of three-dimensional volumes from two-dimensional images. In contrast, synchrotron radiation imaging (SRI) data enables imaging of the heart in 3D without further preparation following DTI. The objective of the study was to validate DTI measurements based on structure tensor analysis of SRI data. One isolated, fixed rat heart was imaged ex vivo with DTI and X-ray phase contrast SRI, and reconstructed at 100 μm and 3.6 μm isotropic resolution respectively. Structure tensors were determined from the SRI data and registered to the DTI data. Excellent agreement in helix angles (HA) and transverse angles (TA) was observed between the DTI and structure tensor synchrotron radiation imaging (STSRI) data, where HA DTI-STSRI  = -1.4° ± 23.2° and TA DTI-STSRI  = -1.4° ± 35.0° (mean ± 1.96 standard deviation across all voxels in the left ventricle). STSRI confirmed that the primary eigenvector of the diffusion tensor corresponds with the cardiomyocyte long-axis across the whole myocardium. We have used STSRI as a novel and high-resolution gold standard for the validation of DTI, allowing like-with-like comparison of three-dimensional tissue structures in the same intact heart free of distortion. This represents a critical step forward in independently verifying the structural basis and informing the interpretation of cardiac DTI data, thereby supporting the further development and adoption of DTI in structure-based electro-mechanical modelling and routine clinical

  10. Parallel workflow tools to facilitate human brain MRI post-processing

    Directory of Open Access Journals (Sweden)

    Zaixu eCui

    2015-05-01

    Full Text Available Multi-modal magnetic resonance imaging (MRI techniques are widely applied in human brain studies. To obtain specific brain measures of interest from MRI datasets, a number of complex image post-processing steps are typically required. Parallel workflow tools have recently been developed, concatenating individual processing steps and enabling fully automated processing of raw MRI data to obtain the final results. These workflow tools are also designed to make optimal use of available computational resources and to support the parallel processing of different subjects or of independent processing steps for a single subject. Automated, parallel MRI post-processing tools can greatly facilitate relevant brain investigations and are being increasingly applied. In this review, we briefly summarize these parallel workflow tools and discuss relevant issues.

  11. First-Passage-Time Distribution for Variable-Diffusion Processes

    Science.gov (United States)

    Barney, Liberty; Gunaratne, Gemunu H.

    2017-05-01

    First-passage-time distribution, which presents the likelihood of a stock reaching a pre-specified price at a given time, is useful in establishing the value of financial instruments and in designing trading strategies. First-passage-time distribution for Wiener processes has a single peak, while that for stocks exhibits a notable second peak within a trading day. This feature has only been discussed sporadically—often dismissed as due to insufficient/incorrect data or circumvented by conversion to tick time—and to the best of our knowledge has not been explained in terms of the underlying stochastic process. It was shown previously that intra-day variations in the market can be modeled by a stochastic process containing two variable-diffusion processes (Hua et al. in, Physica A 419:221-233, 2015). We show here that the first-passage-time distribution of this two-stage variable-diffusion model does exhibit a behavior similar to the empirical observation. In addition, we find that an extended model incorporating overnight price fluctuations exhibits intra- and inter-day behavior similar to those of empirical first-passage-time distributions.

  12. In vivo measurements of relaxation process in the human liver by MRI. The role of respiratory gating/triggering

    DEFF Research Database (Denmark)

    Thomsen, C; Henriksen, O; Ring, P

    1988-01-01

    In vivo estimation of relaxation processes in the liver by magnetic resonance imaging (MRI) may be helpful for characterization of various pathological conditions in the liver. However, such measurements may be significantly hampered by movement of the liver with the respiration. The effect...... of synchronization of data acquisition to the respiratory cycle on measured T1- and T2-relaxation curves was studied in normal subjects, patients with diffuse liver disease, and patients with focal liver pathology. Multi spin echo sequences with five different repetition times were used. The measurements were...... carried out with and without respiratory gating/triggering. In the healthy subjects as well as in the patients with diffuse liver diseases respiratory synchronization did not alter the obtained relaxation curves. However, in the patients with focal pathology the relaxation curves were significantly...

  13. Microstructural changes in ischemic cortical gray matter predicted by a model of diffusion-weighted MRI

    DEFF Research Database (Denmark)

    Vestergaard-Poulsen, Peter; Hansen, Brian; Østergaard, Leif

    2007-01-01

    compartment. A global optimum was found from a wide range of parameter permutations using cluster computing. We also present simulations of cell swelling and changes of exchange rate and intracellular diffusion as possible cellular mechanisms in ischemia. RESULTS: Our model estimates an extracellular volume...... compartments and slow water exchange. Our model reproduces the signal changes observed in ischemia via physiologically credible mechanisms. CONCLUSION: Our modeling suggests that transverse relaxation has a profound influence on the diffusion attenuated MR signal. Our simulations indicate cell swelling...... model to the diffusion-weighted MR signal obtained from cortical gray matter in healthy subjects. Our model includes variable volume fractions, intracellular restriction effects, and exchange between compartments in addition to individual diffusion coefficients and transverse relaxation rates for each...

  14. Processes in arithmetic strategy selection: A fMRI study.

    Directory of Open Access Journals (Sweden)

    Julien eTaillan

    2015-02-01

    Full Text Available This neuroimaging (fMRI study investigated neural correlates of strategy selection. Young adults performed an arithmetic task in two different conditions. In both conditions, participants had to provide estimates of two-digit multiplication problems like 54 x 78. In the choice condition, participants had to select the better of two available rounding strategies, rounding-up strategy (RU (i.e., doing 60x80 = 4,800 or rounding-down strategy (RD (i.e., doing 50x70=3,500 to estimate product of 54x78. In the no-choice condition, participants did not have to select strategy on each problem but were told which strategy to use; they executed RU and RD strategies each on a series of problems. Participants also had a control task (i.e., providing correct products of multiplication problems like 40x50. Brain activations and performance were analyzed as a function of these conditions. Participants were able to frequently choose the better strategy in the choice condition; they were also slower when they executed the difficult RU than the easier RD. Neuroimaging data showed greater brain activations in right anterior cingulate cortex (ACC, dorso-lateral prefrontal cortex (DLPFC, and angular gyrus (ANG, when selecting (relative to executing the better strategy on each problem. Moreover, RU was associated with more parietal cortex activation than RD. These results suggest an important role of fronto-parietal network in strategy selection and have important implications for our further understanding and modelling cognitive processes underlying strategy selection.

  15. Change-point analysis data of neonatal diffusion tensor MRI in preterm and term-born infants

    Directory of Open Access Journals (Sweden)

    Dan Wu

    2017-06-01

    Full Text Available The data presented in this article are related to the research article entitled “Mapping the Critical Gestational Age at Birth that Alters Brain Development in Preterm-born Infants using Multi-Modal MRI” (Wu et al., 2017 [1]. Brain immaturity at birth poses critical neurological risks in the preterm-born infants. We used a novel change-point model to analyze the critical gestational age at birth (GAB that could affect postnatal development, based on diffusion tensor MRI (DTI acquired from 43 preterm and 43 term-born infants in 126 brain regions. In the corresponding research article, we presented change-point analysis of fractional anisotropy (FA and mean diffusivities (MD measurements in these infants. In this article, we offered the relative changes of axonal and radial diffusivities (AD and RD in relation to the change of FA and FA-based change-points, and we also provided the AD- and RD-based change-point results.

  16. Diagnostic utility of novel MRI-based biomarkers for Alzheimer's disease: diffusion tensor imaging and deformation-based morphometry.

    Science.gov (United States)

    Friese, Uwe; Meindl, Thomas; Herpertz, Sabine C; Reiser, Maximilian F; Hampel, Harald; Teipel, Stefan J

    2010-01-01

    We report evidence that multivariate analyses of deformation-based morphometry and diffusion tensor imaging (DTI) data can be used to discriminate between healthy participants and patients with Alzheimer's disease (AD) with comparable diagnostic accuracy. In contrast to other studies on MRI-based biomarkers which usually only focus on a single modality, we derived deformation maps from high-dimensional normalization of T1-weighted images, as well as mean diffusivity maps and fractional anisotropy maps from DTI of the same group of 21 patients with AD and 20 healthy controls. Using an automated multivariate analysis of the entire brain volume, widespread decreased white matter integrity and atrophy effects were found in cortical and subcortical regions of AD patients. Mean diffusivity maps and deformation maps were equally effective in discriminating between AD patients and controls (AUC =0.88 vs. AUC=0.85) while fractional anisotropy maps performed slightly inferior. Combining the maps from different modalities in a logistic regression model resulted in a classification accuracy of AUC=0.86 after leave-one-out cross-validation. It remains to be shown if this automated multivariate analysis of DTI-measures can improve early diagnosis of AD in predementia stages.

  17. Correlation of standardized uptake value and apparent diffusion coefficient in integrated whole-body PET/MRI of primary and recurrent cervical cancer.

    Science.gov (United States)

    Grueneisen, Johannes; Beiderwellen, Karsten; Heusch, Philipp; Buderath, Paul; Aktas, Bahriye; Gratz, Marcel; Forsting, Michael; Lauenstein, Thomas; Ruhlmann, Verena; Umutlu, Lale

    2014-01-01

    To evaluate a potential correlation of the maximum standard uptake value (SUVmax) and the minimum apparent diffusion coefficient (ADCmin) in primary and recurrent cervical cancer based on integrated PET/MRI examinations. 19 consecutive patients (mean age 51.6 years; range 30-72 years) with histopathologically confirmed primary cervical cancer (n = 9) or suspected tumor recurrence (n = 10) were prospectively enrolled for an integrated PET/MRI examination. Two radiologists performed a consensus reading in random order, using a dedicated post-processing software. Polygonal regions of interest (ROI) covering the entire tumor lesions were drawn into PET/MR images to assess SUVmax and into ADC parameter maps to determine ADCmin values. Pearson's correlation coefficients were calculated to assess a potential correlation between the mean values of ADCmin and SUVmax. In 15 out of 19 patients cervical cancer lesions (n = 12) or lymph node metastases (n = 42) were detected. Mean SUVmax (12.5 ± 6.5) and ADCmin (644.5 ± 179.7 × 10(-5) mm2/s) values for all assessed tumor lesions showed a significant but weak inverse correlation (R = -0.342, p correlation between SUVmax and ADCmin (R = -0.692, p correlation. These initial results of this emerging hybrid imaging technique demonstrate the high diagnostic potential of simultaneous PET/MR imaging for the assessment of functional biomarkers, revealing a significant and strong correlation of tumor metabolism and higher cellularity in cervical cancer lesions.

  18. Characterization of diffusivity based on spherical array processing

    DEFF Research Database (Denmark)

    Nolan, Melanie; Fernandez Grande, Efren; Jeong, Cheol-Ho

    2015-01-01

    -dimensional domain and consequently examine some of its fundamental properties: spatial distribution of sound pressure levels, particle velocity and sound intensity. The study allows for visualization of the intensity field inside a reverberant space, and successfully illustrates the behavior of the sound field...... in such an environment. This initial investigation shows the validity of the suggested processing and reveals interesting perspectives for future work. Ultimately, the aim is to define a proper and reliable measure of the diffuse sound field conditions in a reverberation chamber, with the prospect of improving...

  19. Role of MRI and added value of diffusion-weighted and gadolinium-enhanced MRI for the diagnosis of local recurrence from rectal cancer.

    Science.gov (United States)

    Molinelli, Valeria; Angeretti, Maria Gloria; Duka, Ejona; Tarallo, Nicola; Bracchi, Elena; Novario, Raffaele; Fugazzola, Carlo

    2018-03-14

    To evaluate whether the addition of gadolinium-enhanced MRI and diffusion-weighted imaging (DWI) improves T2 sequence performance for the diagnosis of local recurrence (LR) from rectal cancer and to assess which approach is better at formulating this diagnosis among readers with different experience. Forty-three patients with suspected LR underwent pelvic MRI with T2 weighted (T2) sequences, gadolinium fat-suppressed T1 weighted sequences (post-contrast T1), and DWI sequences. Three readers (expert: G, intermediate: E, resident: V) scored the likelihood of LR on T2, T2 + post-contrast T1, T2 + DWI, and T2 + post-contrast T1 + DWI. In total, 18/43 patients had LR; on T2 images, the expert reader achieved an area under the ROC curve (AUC) of 0.916, sensitivity of 88.9%, and specificity of 76%; the intermediate reader achieved values of 0.890, 88.9%, and 48%, respectively, and the resident achieved values of 0.852, 88.9%, and 48%, respectively. DWI significantly improved the AUC value for the expert radiologist by up to 0.999 (p = 0.04), while post-contrast T1 significantly improved the AUC for the resident by up to 0.950 (p = 0.04). For the intermediate reader, both the T2 + DWI AUC and T2 + post-contrast T1 AUC were better than the T2 AUC (0.976 and 0.980, respectively), but with no statistically significant difference. No statistically significant difference was achieved by any of the three readers by comparing either the T2 + DWI AUCs to the T2 + post-contrast T1 AUCs or the AUCs of the two pairs of sequences to those of the combined three sequences. Furthermore, using the T2 sequences alone, all of the readers achieved a fair number of "equivocal" cases: they decreased with the addition of either DWI or post-contrast T1 sequences and, for the two less experienced readers, they decreased even more with the three combined sequences. Both DWI and T1 post-contrast MRI increased diagnostic performance for LR diagnosis compared to T2; however, no

  20. Heat stress presenting with encephalopathy and MRI findings of diffuse cerebral injury and hemorrhage.

    Science.gov (United States)

    Guerrero, Waldo R; Varghese, Shaun; Savitz, Sean; Wu, Tzu Ching

    2013-06-17

    Heat stress results in multiorgan failure and CNS injury. There a few case reports in the literature on the neurological consequences of heat stress. We describe a patient with heat stress presenting with encephalopathy and bilateral cerebral, cerebellar, and thalamic lesions and intraventricular hemorrhage on MRI. Heat stress should be in the differential diagnosis of patients presenting with encephalopathy and elevated serum inflammatory markers especially if the history suggests a preceding episode of hyperthermia.

  1. A renewal jump-diffusion process with threshold dividend strategy

    Science.gov (United States)

    Li, Bo; Wu, Rong; Song, Min

    2009-06-01

    In this paper, we consider a jump-diffusion risk process with the threshold dividend strategy. Both the distributions of the inter-arrival times and the claims are assumed to be in the class of phase-type distributions. The expected discounted dividend function and the Laplace transform of the ruin time are discussed. Motivated by Asmussen [S. Asmussen, Stationary distributions for fluid flow models with or without Brownian noise, Stochastic Models 11 (1) (1995) 21-49], instead of studying the original process, we study the constructed fluid flow process and their closed-form formulas are obtained in terms of matrix expression. Finally, numerical results are provided to illustrate the computation.

  2. Feasibility of a RARE-based sequence for quantitative diffusion-weighted MRI of the spine

    International Nuclear Information System (INIS)

    Raya, J.G.; Dietrich, O.; Sommer, J.; Reiser, M.F.; Baur-Melnyk, A.; Birkenmaier, C.

    2007-01-01

    The feasibility of a diffusion-weighted single-shot fast-spin-echo sequence for the diagnostic work-up of bone marrow diseases was assessed. Twenty healthy controls and 16 patients with various bone marrow pathologies of the spine (bone marrow edema, tumor and inflammation) were examined with a diffusion-weighted single-shot sequence based on a modified rapid acquisition with relaxation enhancement (mRARE) technique; four diffusion weightings (b-values: 50, 250, 500 and 750 s/mm 2 ) in three orthogonal orientations were applied. Apparent diffusion coefficients (ADCs) were determined in the bone marrow and in the intervertebral discs of healthy volunteers and in diseased bone marrow. Ten of the 20 volunteers were repeatedly scanned within 30 min to examine short-time reproducibility. Spatial reproducibility was assessed by measuring ADCs in two different slices including the same lesion in 12 patients. The ADCs of the lesions exhibited significantly higher values, (1.27 ± 0.32) x 10 -3 mm 2 /s, compared with healthy bone marrow, (0.21 ± 0.10) x 10 -3 mm 2 /s. Short-time and spatial reproducibility had a mean coefficient of variation of 2.1% and 6.4%, respectively. The diffusion-weighted mRARE sequence provides a reliable tool for determining quantitative ADCs in vertebral bone marrow with adequate image quality. (orig.)

  3. Image processing techniques for quantification and assessment of brain MRI

    NARCIS (Netherlands)

    Kuijf, H.J.

    2013-01-01

    Magnetic resonance imaging (MRI) is a widely used technique to acquire digital images of the human brain. A variety of acquisition protocols is available to generate images in vivo and noninvasively, giving great opportunities to study the anatomy and physiology of the human brain. In my thesis,

  4. Experimental and theoretical investigations on diffusion process for rare earth ores

    Energy Technology Data Exchange (ETDEWEB)

    He, Ye; Li, Wenzhi Z. [Changchun Univ. (China)

    2013-06-01

    The diffusion reaction kinetics of weathered crust elution-deposited rare earth with mixed ammonium salts was studied. The influence of concentration of reagents and particle size of ore on diffusion rate was investigated. The results showed that the diffusion process and diffusion rate could be improved by increasing reagents concentration and decreasing diffusion flowing rate and particle size. The diffusion process could be explained with the shrinking core Model, which could be controlled by the diffusion rate of reacting reagents in porous solid layer.

  5. Diffusion of samarium into cobalt in the reduction-diffusion process

    International Nuclear Information System (INIS)

    Freitas Nogueira, P. de; Neto, F.B.; Landgraf, F.J.G.

    1998-01-01

    The presence of metallic cobalt in samarium-cobalt powders is a major cause for low magnetic properties in magnets. This paper intends to investigate the effect of time and temperature in the microstructure of powders produced by reduction-diffusion. This process, developed for the production of rare earth-transition metal alloys, consists on the reduction of the rare earth oxide with metallic calcium (or calcium hydride) and its subsequent diffusion into the cobalt particle. In the present work, a mixture of samarium oxide, cobalt powder and metallic calcium was heated to 1100 or 1200 C for 2 or 4 hours in a tubular furnace under one atmosphere of purified argon. The material thereof obtained, a sintered mass is disintegrated by aqueous crepitation. The powder was evaluated in terms of its chemical composition, its samarium yield and the intermetallic compounds present. The samarium, oxygen and calcium content of the powders produced were adequate for magnet production. However, despite the massive formation of the SmCo 5 compound after 2 hours at 1100 C, final homogeneity is attained only after 4 hours at 1200 C, with the presence of SmCo 5 and Sm 2 Co 7 and the absence of the Sm 5 Co 19 compound. Also, metallic cobalt and Sm 2 Co 17 were observed in the materials produced after 2 hours at 1100 or 1200 C. (orig.)

  6. Stochastic processes and applications diffusion processes, the Fokker-Planck and Langevin equations

    CERN Document Server

    Pavliotis, Grigorios A

    2014-01-01

    This book presents various results and techniques from the theory of stochastic processes that are useful in the study of stochastic problems in the natural sciences. The main focus is analytical methods, although numerical methods and statistical inference methodologies for studying diffusion processes are also presented. The goal is the development of techniques that are applicable to a wide variety of stochastic models that appear in physics, chemistry and other natural sciences. Applications such as stochastic resonance, Brownian motion in periodic potentials and Brownian motors are studied and the connection between diffusion processes and time-dependent statistical mechanics is elucidated.                 The book contains a large number of illustrations, examples, and exercises. It will be useful for graduate-level courses on stochastic processes for students in applied mathematics, physics and engineering. Many of the topics covered in this book (reversible diffusions, convergence to eq...

  7. Combined diffusion-weighted, blood oxygen level-dependent, and dynamic contrast-enhanced MRI for characterization and differentiation of renal cell carcinoma.

    Science.gov (United States)

    Notohamiprodjo, Mike; Staehler, Michael; Steiner, Nicole; Schwab, Felix; Sourbron, Steven P; Michaely, Henrik J; Helck, Andreas D; Reiser, Maximilian F; Nikolaou, Konstantin

    2013-06-01

    To investigate a multiparametric magnetic resonance imaging (MRI) approach comprising diffusion-weighted imaging (DWI), blood oxygen-dependent (BOLD), and dynamic contrast-enhanced (DCE) MRI for characterization and differentiation of primary renal cell carcinoma (RCC). Fourteen patients with clear-cell carcinoma and four patients with papillary RCC were examined with DWI, BOLD MRI, and DCE MRI at 1.5T. The apparent diffusion coefficient (ADC) was calculated with a monoexponential decay. The spin-dephasing rate R2* was derived from parametric R2* maps. DCE-MRI was analyzed using a two-compartment exchange model allowing separation of perfusion (plasma flow [FP] and plasma volume [VP]), permeability (permeability surface area product [PS]), and extravascular extracellular volume (VE). Statistical analysis was performed with Wilcoxon signed-rank test, Pearson's correlation coefficient, and receiver operating characteristic curve analysis. Clear-cell RCC showed higher ADC and lower R2* compared to papillary subtypes, but differences were not significant. FP of clear-cell subtypes was significantly higher than in papillary RCC. Perfusion parameters showed moderate but significant inverse correlation with R2*. VE showed moderate inverse correlation with ADC. Fp and Vp showed best sensitivity for histological differentiation. Multiparametric MRI comprising DWI, BOLD, and DCE MRI is feasible for assessment of primary RCC. BOLD moderately correlates to DCE MRI-derived perfusion. ADC shows moderate correlation to the extracellular volume, but does not correlate to tumor oxygenation or perfusion. In this preliminary study DCE-MRI appeared superior to BOLD and DWI for histological differentiation. Copyright © 2013 AUR. Published by Elsevier Inc. All rights reserved.

  8. The Diffusion Process in Small Particles and Brownian Motion

    Science.gov (United States)

    Khoshnevisan, M.

    Albert Einstein in 1926 published his book entitled ''INVESTIGATIONS ON THE THEORY OF THE BROWNIAN MOVEMENT''. He investigated the process of diffusion in an undissociated dilute solution. The diffusion process is subject to Brownian motion. Furthermore, he elucidated the fact that the heat content of a substance will change the position of the single molecules in an irregular fashion. In this paper, I have shown that in order for the displacement of the single molecules to be proportional to the square root of the time, and for v/2 - v 1 Δ =dv/dx , (where v1 and v2 are the concentrations in two cross sections that are separated by a very small distance), ∫ - ∞ ∞ Φ (Δ) dΔ = I and I/τ ∫ - ∞ ∞Δ2/2 Φ (Δ) dΔ = D conditions to hold, then equation (7a) D =√{ 2 D }√{ τ} must be changed to Δ =√{ 2 D }√{ τ} . I have concluded that D =√{ 2 D }√{ τ} is an unintended error, and it has not been amended for almost 90 years in INVESTIGATIONS ON THE THEORY OF THE BROWNIAN MOVEMENT, 1926 publication.

  9. Application of ultrasound processed images in space: assessing diffuse affectations

    Science.gov (United States)

    Pérez-Poch, A.; Bru, C.; Nicolau, C.

    The purpose of this study was to evaluate diffuse affectations in the liver using texture image processing techniques. Ultrasound diagnose equipments are the election of choice to be used in space environments as they are free from hazardous effects on health. However, due to the need for highly trained radiologists to assess the images, this imaging method is mainly applied on focal lesions rather than on non-focal ones. We have conducted a clinical study on 72 patients with different degrees of chronic hepatopaties and a group of control of 18 individuals. All subjects' clinical reports and results of biopsies were compared to the degree of affectation calculated by our computer system , thus validating the method. Full statistical results are given in the present paper showing a good correlation (r=0.61) between pathologist's report and analysis of the heterogenicity of the processed images from the liver. This computer system to analyze diffuse affectations may be used in-situ or via telemedicine to the ground.

  10. Is there a role for diffusion-weighted MRI (DWI) in the diagnosis of central cartilage tumors?

    International Nuclear Information System (INIS)

    Douis, H.; Jeys, L.; Grimer, R.; Vaiyapuri, S.; Davies, A.M.

    2015-01-01

    To assess if diffusion-weighted MRI (DWI) can differentiate between central enchondromas and chondrosarcomas (CS) and if DWI can distinguish low-grade chondroid lesions from high-grade CS. Fifty-two patients with central cartilage tumors were included. Patients underwent conventional MRI and DWI with ADC mapping. The slice on MRI with the most aggressive imaging feature was identified. The corresponding mean and minimum ADC maps of the tumor at this position were measured. There were 24 enchondromas, five atypical cartilaginous lesions, 15 grade 1, three grade 2, two grade 3, and three dedifferentiated CS. Mean ADC values (x 10 -6 mm 2 /s) for enchondromas, atypical cartilaginous tumors, grade 1 CS, grade 2, CS, grade 3 CS and dedifferentiated CS were 1,896, 2,048, 2,152, 2,170, 2,076, and 1,261, respectively. Minimum ADC values (x 10 -6 mm 2 /s) for enchondromas, atypical cartilaginous tumors, grade 1 CS, grade 2, CS, grade 3 CS and dedifferentiated CS were 1,820, 1,752, 2,010, 1,829, 1,752, and 767, respectively. ANOVA test demonstrated a statistically significant difference in mean and minimum ADC values in all groups. Post hoc analysis revealed this was due to difference in mean and minimum ADC values in dedifferentiated CS. The mean ADC value in low-grade chondroid lesions was 2,001, while the ADC value for high-grade CS were 2,132. The minimum ADC value for low-grade chondroid lesions was 1,896, while the minimum ADC for high-grade CS was 1,837. The difference in minimum and mean ADC values was not statistically significant. DWI cannot differentiate between enchondromas and CS and DWI does not aid in the distinction of low-grade chondroid tumors from high-grade CS. (orig.)

  11. Correlation of apparent diffusion coefficient ratio on 3.0 T MRI with prostate cancer Gleason score.

    Science.gov (United States)

    Jyoti, Rajeev; Jain, Tarun Pankaj; Haxhimolla, Hodo; Liddell, Heath; Barrett, Sean Edward

    2018-01-01

    The purpose was to investigate the usefulness of ADC ratio on Diffusion MRI to discriminate between benign and malignant lesions of Prostate. Images of patients who underwent in-gantry MRI guided prostate lesion biopsy were retrospectively analyzed. Prostate Cancers with 20% or more Gleason score (GS) pattern 3 + 3 = 6 in each core or any volume of higher Gleason score pattern were included. ADC ratio was calculated by two reviewers for each lesion. The ADC ratio was calculated for each lesion by dividing the lowest ADC value in a lesion and highest ADC value in normal prostate in peripheral zone (PZ). ADC ratio values were compared with the biopsy result. Data was analysed using independent samples T-test, Spearman correlation, intra-class correlation coefficient (ICC) and Receiver operating characteristic (ROC) curve. 45 lesions in 33 patients were analyzed. 12 lesions were in transitional zone (TZ) and 33 in perpheral zone PZ. All lesions demonstrated an ADC ratio of 0.45 or lower. GS demonstrated a negative correlation with both the ADC value and ADC ratio . However, ADC ratio (p correlation compared to ADC value alone (p = 0.014). There was no significant statistical difference between GS 3 + 4 and GS 4 + 3 mean ADC tumour value (p = 0.167). However when using ADC ratio , there was a significant difference (p = 0.032). ROC curve analysis demonstrated an area under the curve of 0.83 using ADC ratio and 0.76 when using ADC tumour value when discriminating Gleason 6 from Gleason ≥7 tumours. Inter-observer reliability in the calculation of ADC ratios was excellent, with ICC of 0.964. ADC ratio is a reliable and reproducible tool in quantification of diffusion restriction for clinically significant prostate cancer foci.

  12. Modern MRI tools for the characterization of acute demyelinating lesions: value of chemical shift and diffusion-weighted imaging

    International Nuclear Information System (INIS)

    Kueker, W.; Mehnert, F.; Mader, I.; Naegele, T.; Ruff, J.; Gaertner, S.

    2004-01-01

    Acute demyelinating lesions occur in various inflammatory disorders of the CNS. Apart from multiple sclerosis, most cases can be attributed to an overshooting immunological response to infectious agents called acute disseminated encephalomyelitis (ADEM). ADEM, which is mostly characterized by a monophasic course, has a multiphasic variant (MDEM). The early application of corticosteroids has been shown to be beneficial for the outcome; thus, an early diagnosis is highly desirable. Furthermore, the differential diagnosis ruling out neoplastic disorders may be difficult using conventional MRI alone. The potential diagnostic value of advanced MR techniques such as chemical shift imaging (CSI) and diffusion-weighted imaging (DWI) was investigated in a patient with MDEM, who had a new lesion in continuity with the initial disease manifestation. CSI was performed at 1.5 T with a long echo time of 135 ms for the evaluation of N-acetyl-aspartate (NAA) and choline (Cho) and with short TE of 30 ms for macromolecules (mm) and myo-Inositol (mI). DWI was performed using a single-shot isotropic EPI sequence. Whereas acute and chronic areas of demyelination were neither distinguishable on T2- nor on contrast-enhanced T1-weigted images, CSI and DWI revealed different metabolite concentrations and diffusion characteristics within the composite lesion, clearly separating acute from chronic areas of demyelination. In conclusion, the addition of CSI and DWI may add to the diagnostic power of MRI in the setting of demyelinating disorders by identifying areas of acute and chronic demyelination, even in the absence of contrast enhancement. (orig.)

  13. Case report of a young stroke patient showing interim normalization of the MRI diffusion-weighted imaging lesion

    International Nuclear Information System (INIS)

    Ostwaldt, Ann-Christin; Usnich, Tatiana; Nolte, Christian H.; Villringer, Kersten; Fiebach, Jochen B.

    2015-01-01

    In acute ischemic stroke, diffusion weighted imaging (DWI) shows hyperintensities and is considered to indicate irreversibly damaged tissue. We present the case of a young stroke patient with unusual variability in the development of signal intensities within the same vessel territory. A 35-year-old patient presented with symptoms of global aphasia and hypesthesia of the left hand. MRI demonstrated a scattered lesion in the MCA territory. After rtPA therapy the patient received further MRI examination, three times on day 1, and once on day 2, 3, 5 and 43. The posterior part of the lesion showed the usual pattern with increasing DWI hyperintensity and decreased ADC, as well as delayed FLAIR positivity. However, the anterior part of the lesion, which was clearly visible in the first examination completely normalized on the first day and only reappeared on day 2. This was accompanied by a normalization of the ADC as well as an even further delayed FLAIR positivity. We showed that interim normalization of DWI and ADC in the acute phase can not only be found in rodent models of stroke, but also in humans. We propose that DWI lesion development might be more variable during the first 24 h after stroke than previously assumed

  14. Diffusion-weighted MRI to assess response to chemoradiotherapy in rectal cancer: main interpretation pitfalls and their use for teaching

    Energy Technology Data Exchange (ETDEWEB)

    Lambregts, Doenja M.J.; Lahaye, Max J.; Maas, Monique [The Netherlands Cancer Institute, Department of Radiology, Amsterdam (Netherlands); Heeswijk, Miriam M. van [The Netherlands Cancer Institute, Department of Radiology, Amsterdam (Netherlands); Maastricht University Medical Centre, Department of Radiology, Maastricht (Netherlands); Maastricht University Medical Centre, Department of Surgery, Maastricht (Netherlands); Maastricht University, GROW School for Oncology and Developmental Biology, Maastricht (Netherlands); Delli Pizzi, Andrea [Gabriele d' Annunzio University, SS. Annunziate Hospital, Department of Neuroscience and Imaging, Chieti (Italy); Elderen, Saskia G.C. van [Leiden University Medical Centre, Department of Radiology, Leiden (Netherlands); Andrade, Luisa [Hospitais da Universidade de Coimbra, Department of Radiology, Coimbra (Portugal); Peters, Nicky H.G.M.; Osinga-de Jong, Margreet [Zuyderland Medical Center, location Heerlen, Heerlen (Netherlands); Kint, Peter A.M. [Amphia Hospital, Department of Radiology, Breda (Netherlands); Bipat, Shandra [Academic Medical Centre, Department of Radiology, Amsterdam (Netherlands); Ooms, Rik [Maxima Medical Centre, Department of Radiology, Eindhoven-Veldhoven (Netherlands); Beets, Geerard L. [The Netherlands Cancer Institute, Department of Surgery, Amsterdam (Netherlands); Maastricht University, GROW School for Oncology and Developmental Biology, Maastricht (Netherlands); Bakers, Frans C.H. [Maastricht University Medical Centre, Department of Radiology, Maastricht (Netherlands); Beets-Tan, Regina G.H. [The Netherlands Cancer Institute, Department of Radiology, Amsterdam (Netherlands); Maastricht University, GROW School for Oncology and Developmental Biology, Maastricht (Netherlands)

    2017-10-15

    To establish the most common image interpretation pitfalls for non-expert readers using diffusion-weighted imaging (DWI) to assess response to chemoradiotherapy in patients with rectal cancer and to explore the use of these pitfalls in an expert teaching setting. Two independent non-expert readers (R1 and R2) scored the restaging DW MRI scans (b1,000 DWI, in conjunction with ADC maps and T2-W MRI scans for anatomical reference) in 100 patients for the likelihood of a complete response versus residual tumour using a five-point confidence score. The readers received expert feedback and the final response outcome for each case. The supervising expert documented any potential interpretation errors/pitfalls discussed for each case to identify the most common pitfalls. The most common pitfalls were the interpretation of low signal on the ADC map, small susceptibility artefacts, T2 shine-through effects, subopti