Demonstration of Nonlinearity Bias in the Measurement of the Apparent Diffusion Coefficient in Multicenter Trials

PubMed Central

Malyarenko, Dariya; Newitt, David; Wilmes, Lisa; Tudorica, Alina; Helmer, Karl G.; Arlinghaus, Lori R.; Jacobs, Michael A.; Jajamovich, Guido; Taouli, Bachir; Yankeelov, Thomas E.; Huang, Wei; Chenevert, Thomas L.

2015-01-01

Purpose Characterize system-specific bias across common magnetic resonance imaging (MRI) platforms for quantitative diffusion measurements in multicenter trials. Methods Diffusion weighted imaging (DWI) was performed on an ice-water phantom along the superior-inferior (SI) and right-left (RL) orientations spanning ±150 mm. The same scanning protocol was implemented on 14 MRI systems at seven imaging centers. The bias was estimated as a deviation of measured from known apparent diffusion coefficient (ADC) along individual DWI directions. The relative contributions of gradient nonlinearity, shim errors, imaging gradients and eddy currents were assessed independently. The observed bias errors were compared to numerical models. Results The measured systematic ADC errors scaled quadratically with offset from isocenter, and ranged between −55% (SI) and 25% (RL). Nonlinearity bias was dependent on system design and diffusion gradient direction. Consistent with numerical models, minor ADC errors (±5%) due to shim, imaging and eddy currents were mitigated by double echo DWI and image co-registration of individual gradient directions. Conclusion The analysis confirms gradient nonlinearity as a major source of spatial DW bias and variability in off-center ADC measurements across MRI platforms, with minor contributions from shim, imaging gradients and eddy currents. The developed protocol enables empiric description of systematic bias in multicenter quantitative DWI studies. PMID:25940607

Demonstration of nonlinearity bias in the measurement of the apparent diffusion coefficient in multicenter trials.

PubMed

Malyarenko, Dariya I; Newitt, David; J Wilmes, Lisa; Tudorica, Alina; Helmer, Karl G; Arlinghaus, Lori R; Jacobs, Michael A; Jajamovich, Guido; Taouli, Bachir; Yankeelov, Thomas E; Huang, Wei; Chenevert, Thomas L

2016-03-01

Characterize system-specific bias across common magnetic resonance imaging (MRI) platforms for quantitative diffusion measurements in multicenter trials. Diffusion weighted imaging (DWI) was performed on an ice-water phantom along the superior-inferior (SI) and right-left (RL) orientations spanning ± 150 mm. The same scanning protocol was implemented on 14 MRI systems at seven imaging centers. The bias was estimated as a deviation of measured from known apparent diffusion coefficient (ADC) along individual DWI directions. The relative contributions of gradient nonlinearity, shim errors, imaging gradients, and eddy currents were assessed independently. The observed bias errors were compared with numerical models. The measured systematic ADC errors scaled quadratically with offset from isocenter, and ranged between -55% (SI) and 25% (RL). Nonlinearity bias was dependent on system design and diffusion gradient direction. Consistent with numerical models, minor ADC errors (± 5%) due to shim, imaging and eddy currents were mitigated by double echo DWI and image coregistration of individual gradient directions. The analysis confirms gradient nonlinearity as a major source of spatial DW bias and variability in off-center ADC measurements across MRI platforms, with minor contributions from shim, imaging gradients and eddy currents. The developed protocol enables empiric description of systematic bias in multicenter quantitative DWI studies. © 2015 Wiley Periodicals, Inc.

The importance of correcting for signal drift in diffusion MRI.

PubMed

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

2017-01-01

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. 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, and the effects on diffusion kurtosis tensor estimation in phantom and in vivo data were quantified. Scalar metrics (eigenvalues, fractional anisotropy, mean diffusivity, mean kurtosis) and directional information (first eigenvectors and tractography) were investigated. Signal drift, a global signal decrease with subsequently acquired images in the scan, was observed in phantom data on all three scanners, with varying magnitudes up to 5% in a 15-min scan. The signal drift has a noticeable effect on the estimation of diffusion parameters. All investigated quantitative parameters as well as tractography were affected by this artifactual signal decrease during the scan. By interspersing the non-diffusion-weighted images throughout the session, the signal decrease can be estimated and compensated for before data analysis; minimizing the detrimental effects on subsequent MRI analyses. Magn Reson Med 77:285-299, 2017. © 2016 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. © 2016 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine.

Individual classification of Alzheimer's disease with diffusion magnetic resonance imaging.

PubMed

Schouten, Tijn M; Koini, Marisa; Vos, Frank de; Seiler, Stephan; Rooij, Mark de; Lechner, Anita; Schmidt, Reinhold; Heuvel, Martijn van den; Grond, Jeroen van der; Rombouts, Serge A R B

2017-05-15

Diffusion magnetic resonance imaging (MRI) is a powerful non-invasive method to study white matter integrity, and is sensitive to detect differences in Alzheimer's disease (AD) patients. Diffusion MRI may be able to contribute towards reliable diagnosis of AD. We used diffusion MRI to classify AD patients (N=77), and controls (N=173). We use different methods to extract information from the diffusion MRI data. First, we use the voxel-wise diffusion tensor measures that have been skeletonised using tract based spatial statistics. Second, we clustered the voxel-wise diffusion measures with independent component analysis (ICA), and extracted the mixing weights. Third, we determined structural connectivity between Harvard Oxford atlas regions with probabilistic tractography, as well as graph measures based on these structural connectivity graphs. Classification performance for voxel-wise measures ranged between an AUC of 0.888, and 0.902. The ICA-clustered measures ranged between an AUC of 0.893, and 0.920. The AUC for the structural connectivity graph was 0.900, while graph measures based upon this graph ranged between an AUC of 0.531, and 0.840. All measures combined with a sparse group lasso resulted in an AUC of 0.896. Overall, fractional anisotropy clustered into ICA components was the best performing measure. These findings may be useful for future incorporation of diffusion MRI into protocols for AD classification, or as a starting point for early detection of AD using diffusion MRI. Copyright © 2017 Elsevier Inc. All rights reserved.

Clinical utility for diffusion MRI sequence in emergency and inpatient spine protocols.

PubMed

Hoch, Michael J; Rispoli, Joanne; Bruno, Mary; Wauchope, Mervin; Lui, Yvonne W; Shepherd, Timothy M

Diffusion imaging of the spine has the potential to change clinical management, but is challenging due to the small size of the cord and susceptibility artifacts from adjacent structures. Reduced field-of-view (rFOV) diffusion can improve image quality by decreasing the echo train length. Over the past 2 years, we have acquired a rFOV diffusion sequence for MRI spine protocols on most inpatients and emergency room patients. We provide selected imaging diagnoses to illustrate the utility of including diffusion spine MRI in clinical practice. Our experiences support using diffusion MRI to improve diagnostic certainty and facilitate prompt treatment or clinical management. Copyright © 2017 Elsevier Inc. All rights reserved.

Optimizing Filter-Probe Diffusion Weighting in the Rat Spinal Cord for Human Translation

PubMed Central

Budde, Matthew D.; Skinner, Nathan P.; Muftuler, L. Tugan; Schmit, Brian D.; Kurpad, Shekar N.

2017-01-01

Diffusion tensor imaging (DTI) is a promising biomarker of spinal cord injury (SCI). In the acute aftermath, DTI in SCI animal models consistently demonstrates high sensitivity and prognostic performance, yet translation of DTI to acute human SCI has been limited. In addition to technical challenges, interpretation of the resulting metrics is ambiguous, with contributions in the acute setting from both axonal injury and edema. Novel diffusion MRI acquisition strategies such as double diffusion encoding (DDE) have recently enabled detection of features not available with DTI or similar methods. In this work, we perform a systematic optimization of DDE using simulations and an in vivo rat model of SCI and subsequently implement the protocol to the healthy human spinal cord. First, two complementary DDE approaches were evaluated using an orientationally invariant or a filter-probe diffusion encoding approach. While the two methods were similar in their ability to detect acute SCI, the filter-probe DDE approach had greater predictive power for functional outcomes. Next, the filter-probe DDE was compared to an analogous single diffusion encoding (SDE) approach, with the results indicating that in the spinal cord, SDE provides similar contrast with improved signal to noise. In the SCI rat model, the filter-probe SDE scheme was coupled with a reduced field of view (rFOV) excitation, and the results demonstrate high quality maps of the spinal cord without contamination from edema and cerebrospinal fluid, thereby providing high sensitivity to injury severity. The optimized protocol was demonstrated in the healthy human spinal cord using the commercially-available diffusion MRI sequence with modifications only to the diffusion encoding directions. Maps of axial diffusivity devoid of CSF partial volume effects were obtained in a clinically feasible imaging time with a straightforward analysis and variability comparable to axial diffusivity derived from DTI. Overall, the results and optimizations describe a protocol that mitigates several difficulties with DTI of the spinal cord. Detection of acute axonal damage in the injured or diseased spinal cord will benefit the optimized filter-probe diffusion MRI protocol outlined here. PMID:29311786

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

PubMed

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.

Magnetic resonance imaging in experimental stroke and comparison with histology: systematic review and meta-analysis.

PubMed

Milidonis, Xenios; Marshall, Ian; Macleod, Malcolm R; Sena, Emily S

2015-03-01

Because the new era of preclinical stroke research demands improvements in validity and generalizability of findings, moving from single site to multicenter studies could be pivotal. However, the conduct of magnetic resonance imaging (MRI) in stroke remains ill-defined. We sought to assess the variability in the use of MRI for evaluating lesions post stroke and to examine the possibility as an alternative to gold standard histology for measuring the infarct size. We identified animal studies of ischemic stroke reporting lesion sizes using MRI. We assessed the degree of heterogeneity and reporting of scanning protocols, postprocessing methods, study design characteristics, and study quality. Studies performing histological evaluation of infarct size were further selected to compare with corresponding MRI using meta-regression. Fifty-four articles undertaking a total of 78 different MRI scanning protocols met the inclusion criteria. T2-weighted imaging was most frequently used (83% of the studies), followed by diffusion-weighted imaging (43%). Reporting of the imaging parameters was adequate, but heterogeneity between studies was high. Twelve studies assessed the infarct size using both MRI and histology at corresponding time points, with T2-weighted imaging-based treatment effect having a significant positive correlation with histology (; P<0.001). Guidelines for standardized use and reporting of MRI in preclinical stroke are urgently needed. T2-weighted imaging could be used as an effective in vivo alternative to histology for estimating treatment effects based on the extent of infarction; however, additional studies are needed to explore the effect of individual parameters. © 2015 American Heart Association, Inc.

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

PubMed

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.

Optimized magnetic resonance diffusion protocol for ex-vivo whole human brain imaging with a clinical scanner

NASA Astrophysics Data System (ADS)

Scherrer, Benoit; Afacan, Onur; Stamm, Aymeric; Singh, Jolene; Warfield, Simon K.

2015-03-01

Diffusion-weighted magnetic resonance imaging (DW-MRI) provides a novel insight into the brain to facilitate our understanding of the brain connectivity and microstructure. While in-vivo DW-MRI enables imaging of living patients and longitudinal studies of brain changes, post-mortem ex-vivo DW-MRI has numerous advantages. Ex-vivo imaging benefits from greater resolution and sensitivity due to the lack of imaging time constraints; the use of tighter fitting coils; and the lack of movement artifacts. This allows characterization of normal and abnormal tissues with unprecedented resolution and sensitivity, facilitating our ability to investigate anatomical structures that are inaccessible in-vivo. This also offers the opportunity to develop today novel imaging biomarkers that will, with tomorrow's MR technology, enable improved in-vivo assessment of the risk of disease in an individual. Post-mortem studies, however, generally rely on the fixation of specimen to inhibit tissue decay which starts as soon as tissue is deprived from its blood supply. Unfortunately, fixation of tissues substantially alters tissue diffusivity profiles. In addition, ex-vivo DW-MRI requires particular care when packaging the specimen because the presence of microscopic air bubbles gives rise to geometric and intensity image distortion. In this work, we considered the specific requirements of post-mortem imaging and designed an optimized protocol for ex-vivo whole brain DW-MRI using a human clinical 3T scanner. Human clinical 3T scanners are available to a large number of researchers and, unlike most animal scanners, have a bore diameter large enough to image a whole human brain. Our optimized protocol will facilitate widespread ex-vivo investigations of large specimen.

Post-mortem inference of the human hippocampal connectivity and microstructure using ultra-high field diffusion MRI at 11.7 T.

PubMed

Beaujoin, Justine; Palomero-Gallagher, Nicola; Boumezbeur, Fawzi; Axer, Markus; Bernard, Jeremy; Poupon, Fabrice; Schmitz, Daniel; Mangin, Jean-François; Poupon, Cyril

2018-06-01

The human hippocampus plays a key role in memory management and is one of the first structures affected by Alzheimer's disease. Ultra-high magnetic resonance imaging provides access to its inner structure in vivo. However, gradient limitations on clinical systems hinder access to its inner connectivity and microstructure. A major target of this paper is the demonstration of diffusion MRI potential, using ultra-high field (11.7 T) and strong gradients (750 mT/m), to reveal the extra- and intra-hippocampal connectivity in addition to its microstructure. To this purpose, a multiple-shell diffusion-weighted acquisition protocol was developed to reach an ultra-high spatio-angular resolution with a good signal-to-noise ratio. The MRI data set was analyzed using analytical Q-Ball Imaging, Diffusion Tensor Imaging (DTI), and Neurite Orientation Dispersion and Density Imaging models. High Angular Resolution Diffusion Imaging estimates allowed us to obtain an accurate tractography resolving more complex fiber architecture than DTI models, and subsequently provided a map of the cross-regional connectivity. The neurite density was akin to that found in the histological literature, revealing the three hippocampal layers. Moreover, a gradient of connectivity and neurite density was observed between the anterior and the posterior part of the hippocampus. These results demonstrate that ex vivo ultra-high field/ultra-high gradients diffusion-weighted MRI allows the mapping of the inner connectivity of the human hippocampus, its microstructure, and to accurately reconstruct elements of the polysynaptic intra-hippocampal pathway using fiber tractography techniques at very high spatial/angular resolutions.

MR evaluation of breast lesions obtained by diffusion-weighted imaging with background body signal suppression (DWIBS) and correlations with histological findings.

PubMed

Moschetta, Marco; Telegrafo, Michele; Rella, Leonarda; Capolongo, Arcangela; Stabile Ianora, Amato Antonio; Angelelli, Giuseppe

2014-07-01

Diffusion imaging represents a new imaging tool for the diagnosis of breast cancer. This study aims to investigate the role of diffusion-weighted MRI with background body signal suppression (DWIBS) for evaluating breast lesions. 90 patients were prospectively evaluated by MRI with STIR, TSE-T2, contrast enhanced THRIVE-T1 and DWIBS sequences. DWIBS were analyzed searching for the presence of breast lesions and calculating the ADC value. ADC values of ≤1.44×10(-3)mm(2)/s were considered suspicious for malignancy. This analysis was then compared with the histological findings. Sensitivity, specificity, diagnostic accuracy (DA), positive predictive value (PPV) and negative (NPV) were calculated. In 53/90 (59%) patients, DWIBS indicated the presence of breast lesions, 16 (30%) with ADC values of >1.44 and 37 (70%) with ADC≤1.44. The comparison with histology showed 25 malignant and 28 benign lesions. DWIBS sequences obtained sensitivity, specificity, DA, PPV and NPV values of 100, 82, 87, 68 and 100%, respectively. DWIBS can be proposed in the MRI breast protocol representing an accurate diagnostic complement. Copyright © 2014 Elsevier Inc. All rights reserved.

In vivo High Angular Resolution Diffusion-Weighted Imaging of Mouse Brain at 16.4 Tesla

PubMed Central

Alomair, Othman I.; Brereton, Ian M.; Smith, Maree T.; Galloway, Graham J.; Kurniawan, Nyoman D.

2015-01-01

Magnetic Resonance Imaging (MRI) of the rodent brain at ultra-high magnetic fields (> 9.4 Tesla) offers a higher signal-to-noise ratio that can be exploited to reduce image acquisition time or provide higher spatial resolution. However, significant challenges are presented due to a combination of longer T 1 and shorter T 2/T2* relaxation times and increased sensitivity to magnetic susceptibility resulting in severe local-field inhomogeneity artefacts from air pockets and bone/brain interfaces. The Stejskal-Tanner spin echo diffusion-weighted imaging (DWI) sequence is often used in high-field rodent brain MRI due to its immunity to these artefacts. To accurately determine diffusion-tensor or fibre-orientation distribution, high angular resolution diffusion imaging (HARDI) with strong diffusion weighting (b >3000 s/mm2) and at least 30 diffusion-encoding directions are required. However, this results in long image acquisition times unsuitable for live animal imaging. In this study, we describe the optimization of HARDI acquisition parameters at 16.4T using a Stejskal-Tanner sequence with echo-planar imaging (EPI) readout. EPI segmentation and partial Fourier encoding acceleration were applied to reduce the echo time (TE), thereby minimizing signal decay and distortion artefacts while maintaining a reasonably short acquisition time. The final HARDI acquisition protocol was achieved with the following parameters: 4 shot EPI, b = 3000 s/mm2, 64 diffusion-encoding directions, 125×150 μm2 in-plane resolution, 0.6 mm slice thickness, and 2h acquisition time. This protocol was used to image a cohort of adult C57BL/6 male mice, whereby the quality of the acquired data was assessed and diffusion tensor imaging (DTI) derived parameters were measured. High-quality images with high spatial and angular resolution, low distortion and low variability in DTI-derived parameters were obtained, indicating that EPI-DWI is feasible at 16.4T to study animal models of white matter (WM) diseases. PMID:26110770

Intravascular lymphoma: magnetic resonance imaging correlates of disease dynamics within the central nervous system

PubMed Central

Baehring, J; Henchcliffe, C; Ledezma, C; Fulbright, R; Hochberg, F

2005-01-01

Background: Intravascular lymphoma (IVL) is a rare non-Hodgkin's lymphoma with relative predilection for the central nervous system. In the absence of extraneural manifestations, the disease is not recognised until autopsy in the majority of cases underlining the need for new clinical markers. Methods: This is a retrospective series of five patients with IVL seen at a single institution over three years. An advanced magnetic resonance imaging (MRI) protocol was performed at various time points prior to diagnosis and during treatment. Results: MRI revealed multiple lesions scattered throughout the cerebral hemispheres; the brainstem, cerebellum, and spinal cord were less frequently involved. On initial presentation, hyperintense lesions were seen on diffusion weighted images suggestive of ischaemia in three of four patients in whom the images were obtained at that time point. In four patients lesions were also identifiable as hyperintense areas on fluid attenuated inversion recovery (FLAIR) sequences. Initial contrast enhancement was encountered in three cases. Diffusion weighted imaging lesions either vanished or followed the typical pattern of an ischaemic small vessel stroke with evolution of abnormal FLAIR signal followed by enhancement with gadolinium in the subacute stage and tissue loss in the chronic stage. Diffusion weighted imaging and FLAIR abnormalities proved to be partially reversible, correlating with the response to chemotherapy. Conclusion: We provide the first detailed description of the dynamic pattern of diffusion weighted MRI in IVL. These patterns in combination with systemic findings may facilitate early diagnosis and serve as a new tool to monitor treatment response. PMID:15774442

SU-F-I-16: Short Breast MRI with High-Resolution T2-Weighted and Dynamic Contrast Enhanced T1-Weighted Images

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

Ma, J; Son, J; Arun, B

Purpose: To develop and demonstrate a short breast (sb) MRI protocol that acquires both T2-weighted and dynamic contrast-enhanced T1-weighted images in approximately ten minutes. Methods: The sb-MRI protocol consists of two novel pulse sequences. The first is a flexible fast spin-echo triple-echo Dixon (FTED) sequence for high-resolution fat-suppressed T2-weighted imaging, and the second is a 3D fast dual-echo spoiled gradient sequence (FLEX) for volumetric fat-suppressed T1-weighted imaging before and post contrast agent injection. The flexible FTED sequence replaces each single readout during every echo-spacing period of FSE with three fast-switching bipolar readouts to produce three raw images in a singlemore » acquisition. These three raw images are then post-processed using a Dixon algorithm to generate separate water-only and fat-only images. The FLEX sequence acquires two echoes using dual-echo readout after each RF excitation and the corresponding images are post-processed using a similar Dixon algorithm to yield water-only and fat-only images. The sb-MRI protocol was implemented on a 3T MRI scanner and used for patients who had undergone concurrent clinical MRI for breast cancer screening. Results: With the same scan parameters (eg, spatial coverage, field of view, spatial and temporal resolution) as the clinical protocol, the total scan-time of the sb-MRI protocol (including the localizer, bilateral T2-weighted, and dynamic contrast-enhanced T1-weighted images) was 11 minutes. In comparison, the clinical breast MRI protocol took 43 minutes. Uniform fat suppression and high image quality were consistently achieved by sb-MRI. Conclusion: We demonstrated a sb-MRI protocol comprising both T2-weighted and dynamic contrast-enhanced T1-weighted images can be performed in approximately ten minutes. The spatial and temporal resolution of the images easily satisfies the current breast MRI accreditation guidelines by the American College of Radiology. The protocol has the potential of making breast MRI more widely accessible to and more tolerable by the patients. JMA is the inventor of United States patents that are owned by the University of Texas Board of Regents and currently licensed to GE Healthcare and Siemens Gmbh.« less

Comparison of BOLD, diffusion-weighted fMRI and ADC-fMRI for stimulation of the primary visual system with a block paradigm.

PubMed

Nicolas, R; Gros-Dagnac, H; Aubry, F; Celsis, P

2017-06-01

The blood oxygen level-dependent (BOLD) effect is extensively used for functional MRI (fMRI) but presents some limitations. Diffusion-weighted fMRI (DfMRI) has been proposed as a method more tightly linked to neuronal activity. This work proposes a protocol of DfMRI acquired for several b-values and diffusion directions that is compared to gradient-echo BOLD (GE-BOLD) and to repeated spin-echo BOLD (SE-BOLD, acquisitions performed with b=0s/mm 2 ), which was also used to ensure the reproducibility of the response. A block stimulation paradigm of the primary visual system (V1) was performed in 12 healthy subjects with checkerboard alternations (2Hz frequency). DfMRI was performed at 3T with 5 b-values (b=1500, 1000, 500, 250, 0s/mm 2 ) with TR/TE=1004/93ms, Δ/δ=45.4ms/30ms, and 6 spatial directions for diffusion measures. GE-BOLD was performed with a similar block stimulation design timing. Apparent Diffusion Coefficient (ADC)-fMRI was computed with all b-values used. An identical Z-score level was used for all fMRI modalities for the comparison of volumes of activation. ADC-fMRI and SE-BOLD fMRI activation locations were compared in a voxel-based analysis to a cytoarchitectural probability map of V1. SE-BOLD activation volumes represented only 55% of the GE-BOLD activation volumes (P<0.0001). DfMRI activation volumes averaged for all b-values acquired represented only 12% of GE-BOLD (P<0.0001) and only 22% of SE-BOLD activation volumes (P<0.005). Compared to SE-BOLD-fMRI, ADC-fMRI activations showed fewer pixels outside of V1 and a higher average probability of belonging to V1. DfMRI and ADC-fMRI acquisition at 3T could be easily post-processed with common neuro-imaging software. DfMRI and ADC-fMRI activation volumes were significantly smaller than those obtained with SE-BOLD. ADC-fMRI activations were more precisely localized in V1 than those of SE-BOLD-fMRI. This validated the increased capability of ADC-fMRI compared to BOLD to enhance the precision of localizing an fMRI activation in the cyto-architectural zone V1, thereby justifying the use of ADC-fMRI for neuro-scientific studies. Copyright © 2017 Elsevier Inc. All rights reserved.

Real Diffusion-Weighted MRI Enabling True Signal Averaging and Increased Diffusion Contrast

PubMed Central

Eichner, Cornelius; Cauley, Stephen F; Cohen-Adad, Julien; Möller, Harald E; Turner, Robert; Setsompop, Kawin; Wald, Lawrence L

2015-01-01

This project aims to characterize the impact of underlying noise distributions on diffusion-weighted imaging. The noise floor is a well-known problem for traditional magnitude-based diffusion-weighted MRI (dMRI) data, leading to biased diffusion model fits and inaccurate signal averaging. Here, we introduce a total-variation-based algorithm to eliminate shot-to-shot phase variations of complex-valued diffusion data with the intention to extract real-valued dMRI datasets. The obtained real-valued diffusion data are no longer superimposed by a noise floor but instead by a zero-mean Gaussian noise distribution, yielding dMRI data without signal bias. We acquired high-resolution dMRI data with strong diffusion weighting and, thus, low signal-to-noise ratio. Both the extracted real-valued and traditional magnitude data were compared regarding signal averaging, diffusion model fitting and accuracy in resolving crossing fibers. Our results clearly indicate that real-valued diffusion data enables idealized conditions for signal averaging. Furthermore, the proposed method enables unbiased use of widely employed linear least squares estimators for model fitting and demonstrates an increased sensitivity to detect secondary fiber directions with reduced angular error. The use of phase-corrected, real-valued data for dMRI will therefore help to clear the way for more detailed and accurate studies of white matter microstructure and structural connectivity on a fine scale. PMID:26241680

MRI diffusion tensor reconstruction with PROPELLER data acquisition.

PubMed

Cheryauka, Arvidas B; Lee, James N; Samsonov, Alexei A; Defrise, Michel; Gullberg, Grant T

2004-02-01

MRI diffusion imaging is effective in measuring the diffusion tensor in brain, cardiac, liver, and spinal tissue. Diffusion tensor tomography MRI (DTT MRI) method is based on reconstructing the diffusion tensor field from measurements of projections of the tensor field. Projections are obtained by appropriate application of rotated diffusion gradients. In the present paper, the potential of a novel data acquisition scheme, PROPELLER (Periodically Rotated Overlapping ParallEL Lines with Enhanced Reconstruction), is examined in combination with DTT MRI for its capability and sufficiency for diffusion imaging. An iterative reconstruction algorithm is used to reconstruct the diffusion tensor field from rotated diffusion weighted blades by appropriate rotated diffusion gradients. DTT MRI with PROPELLER data acquisition shows significant potential to reduce the number of weighted measurements, avoid ambiguity in reconstructing diffusion tensor parameters, increase signal-to-noise ratio, and decrease the influence of signal distortion.

Comparison of unsupervised classification methods for brain tumor segmentation using multi-parametric MRI.

PubMed

Sauwen, N; Acou, M; Van Cauter, S; Sima, D M; Veraart, J; Maes, F; Himmelreich, U; Achten, E; Van Huffel, S

2016-01-01

Tumor segmentation is a particularly challenging task in high-grade gliomas (HGGs), as they are among the most heterogeneous tumors in oncology. An accurate delineation of the lesion and its main subcomponents contributes to optimal treatment planning, prognosis and follow-up. Conventional MRI (cMRI) is the imaging modality of choice for manual segmentation, and is also considered in the vast majority of automated segmentation studies. Advanced MRI modalities such as perfusion-weighted imaging (PWI), diffusion-weighted imaging (DWI) and magnetic resonance spectroscopic imaging (MRSI) have already shown their added value in tumor tissue characterization, hence there have been recent suggestions of combining different MRI modalities into a multi-parametric MRI (MP-MRI) approach for brain tumor segmentation. In this paper, we compare the performance of several unsupervised classification methods for HGG segmentation based on MP-MRI data including cMRI, DWI, MRSI and PWI. Two independent MP-MRI datasets with a different acquisition protocol were available from different hospitals. We demonstrate that a hierarchical non-negative matrix factorization variant which was previously introduced for MP-MRI tumor segmentation gives the best performance in terms of mean Dice-scores for the pathologic tissue classes on both datasets.

Update on the MRI Core of the Alzheimer's Disease Neuroimaging Initiative

PubMed Central

Jack, Clifford R; Bernstein, Matt A; Borowski, Bret J; Gunter, Jeffrey L; Fox, Nick C; Thompson, Paul M; Schuff, Norbert; Krueger, Gunnar; Killiany, Ronald J; DeCarli, Charles S; Dale, Anders M; Weiner, Michael W

2010-01-01

Functions of the ADNI MRI core fall into three categories: (1) those of the central MRI core lab at Mayo Clinic, Rochester, Minnesota, needed to generate high quality MRI data in all subjects at each time point; (2) those of the funded ADNI MRI core imaging analysis groups responsible for analyzing the MRI data, and (3) the joint function of the entire MRI core in designing and problem solving MR image acquisition, pre-processing and analyses methods. The primary objective of ADNI was and continues to be improving methods for clinical trials in Alzheimer's disease. Our approach to the present (“ADNI-GO”) and future (“ADNI-2”, if funded) MRI protocol will be to maintain MRI methodological consistency in previously enrolled “ADNI-1” subjects who are followed longitudinally in ADNI-GO and ADNI-2. We will modernize and expand the MRI protocol for all newly enrolled ADNI-GO and ADNI-2 subjects. All newly enrolled subjects will be scanned at 3T with a core set of three sequence types: 3D T1-weighted volume, FLAIR, and a long TE gradient echo volumetric acquisition for micro hemorrhage detection. In addition to this core ADNI-GO and ADNI-2 protocol, we will perform vendor specific pilot sub-studies of arterial spin labeling perfusion, resting state functional connectivity and diffusion tensor imaging. One each of these sequences will be added to the core protocol on systems from each MRI vendor. These experimental sub-studies are designed to demonstrate the feasibility of acquiring useful data in a multi-center (but single vendor) setting for these three emerging MRI applications. PMID:20451869

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

PubMed

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.

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

PubMed Central

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. PMID:29494639

Diffusion pseudonormalization and clinical outcome in term neonates with hypoxic-ischemic encephalopathy.

PubMed

Hayakawa, Katsumi; Koshino, Sachiko; Tanda, Koichi; Nishimura, Akira; Sato, Osamu; Morishita, Hiroyuki; Ito, Takaaki

2018-06-01

Pseudonormalization of diffusion-weighted magnetic resonance imaging (MRI) can lead to underestimation of brain injury in newborns with hypoxic-ischemic encephalopathy (HIE), posing a significant problem. We have noticed that some neonates show pseudonormalization negativity on diffusion-weighted imaging. To compare pseudonormalization negativity with clinical outcomes. Seventeen term neonates with moderate or severe HIE underwent therapeutic hypothermia. They were examined by MRI twice at mean ages of 3 days and 10 days. We evaluated the presence of restricted diffusion, and also the presence or absence of pseudonormalization, by diffusion-weighted imaging at the time of the second MRI, and correlated the results with clinical outcome. DWI demonstrated no abnormality in seven neonates. Among the 10 neonates with abnormal diffusion-weighted imaging findings, 2 were positive for pseudonormalization and 8 were negative. Among neonates with normal diffusion-weighted imaging findings and with positivity for pseudonormalization, none had major disability. Among the eight neonates with pseudonormalization negativity, all but one, who was lost to follow-up, had major disability. Abnormal diffusion-weighted imaging with pseudonormalization negativity might be predictive of severe brain injury and major disability. The second-week MRI is important for the judgment of pseudonormalization.

The role of MRI in axillary lymph node imaging in breast cancer patients: a systematic review.

PubMed

Kuijs, V J L; Moossdorff, M; Schipper, R J; Beets-Tan, R G H; Heuts, E M; Keymeulen, K B M I; Smidt, M L; Lobbes, M B I

2015-04-01

To assess whether MRI can exclude axillary lymph node metastasis, potentially replacing sentinel lymph node biopsy (SLNB), and consequently eliminating the risk of SLNB-associated morbidity. PubMed, Cochrane, Medline and Embase databases were searched for relevant publications up to July 2014. Studies were selected based on predefined inclusion and exclusion criteria and independently assessed by two reviewers using a standardised extraction form. Sixteen eligible studies were selected from 1,372 publications identified by the search. A dedicated axillary protocol [sensitivity 84.7 %, negative predictive value (NPV) 95.0 %] was superior to a standard protocol covering both the breast and axilla simultaneously (sensitivity 82.0 %, NPV 82.6 %). Dynamic, contrast-enhanced MRI had a lower median sensitivity (60.0 %) and NPV (80.0 %) compared to non-enhanced T1w/T2w sequences (88.4, 94.7 %), diffusion-weighted imaging (84.2, 90.6 %) and ultrasmall superparamagnetic iron oxide (USPIO)- enhanced T2*w sequences (83.0, 95.9 %). The most promising results seem to be achievable when using non-enhanced T1w/T2w and USPIO-enhanced T2*w sequences in combination with a dedicated axillary protocol (sensitivity 84.7 % and NPV 95.0 %). The diagnostic performance of some MRI protocols for excluding axillary lymph node metastases approaches the NPV needed to replace SLNB. However, current observations are based on studies with heterogeneous study designs and limited populations. • Some axillary MRI protocols approach the NPV of an SLNB procedure. • Dedicated axillary MRI is more accurate than protocols also covering the breast. • T1w/T2w protocols combined with USPIO-enhanced sequences are the most promising sequences.

Multisite longitudinal reliability of tract-based spatial statistics in diffusion tensor imaging of healthy elderly subjects.

PubMed

Jovicich, Jorge; Marizzoni, Moira; Bosch, Beatriz; Bartrés-Faz, David; Arnold, Jennifer; Benninghoff, Jens; Wiltfang, Jens; Roccatagliata, Luca; Picco, Agnese; Nobili, Flavio; Blin, Oliver; Bombois, Stephanie; Lopes, Renaud; Bordet, Régis; Chanoine, Valérie; Ranjeva, Jean-Philippe; Didic, Mira; Gros-Dagnac, Hélène; Payoux, Pierre; Zoccatelli, Giada; Alessandrini, Franco; Beltramello, Alberto; Bargalló, Núria; Ferretti, Antonio; Caulo, Massimo; Aiello, Marco; Ragucci, Monica; Soricelli, Andrea; Salvadori, Nicola; Tarducci, Roberto; Floridi, Piero; Tsolaki, Magda; Constantinidis, Manos; Drevelegas, Antonios; Rossini, Paolo Maria; Marra, Camillo; Otto, Josephin; Reiss-Zimmermann, Martin; Hoffmann, Karl-Titus; Galluzzi, Samantha; Frisoni, Giovanni B

2014-11-01

Large-scale longitudinal neuroimaging studies with diffusion imaging techniques are necessary to test and validate models of white matter neurophysiological processes that change in time, both in healthy and diseased brains. The predictive power of such longitudinal models will always be limited by the reproducibility of repeated measures acquired during different sessions. At present, there is limited quantitative knowledge about the across-session reproducibility of standard diffusion metrics in 3T multi-centric studies on subjects in stable conditions, in particular when using tract based spatial statistics and with elderly people. In this study we implemented a multi-site brain diffusion protocol in 10 clinical 3T MRI sites distributed across 4 countries in Europe (Italy, Germany, France and Greece) using vendor provided sequences from Siemens (Allegra, Trio Tim, Verio, Skyra, Biograph mMR), Philips (Achieva) and GE (HDxt) scanners. We acquired DTI data (2 × 2 × 2 mm(3), b = 700 s/mm(2), 5 b0 and 30 diffusion weighted volumes) of a group of healthy stable elderly subjects (5 subjects per site) in two separate sessions at least a week apart. For each subject and session four scalar diffusion metrics were considered: fractional anisotropy (FA), mean diffusivity (MD), radial diffusivity (RD) and axial (AD) diffusivity. The diffusion metrics from multiple subjects and sessions at each site were aligned to their common white matter skeleton using tract-based spatial statistics. The reproducibility at each MRI site was examined by looking at group averages of absolute changes relative to the mean (%) on various parameters: i) reproducibility of the signal-to-noise ratio (SNR) of the b0 images in centrum semiovale, ii) full brain test-retest differences of the diffusion metric maps on the white matter skeleton, iii) reproducibility of the diffusion metrics on atlas-based white matter ROIs on the white matter skeleton. Despite the differences of MRI scanner configurations across sites (vendors, models, RF coils and acquisition sequences) we found good and consistent test-retest reproducibility. White matter b0 SNR reproducibility was on average 7 ± 1% with no significant MRI site effects. Whole brain analysis resulted in no significant test-retest differences at any of the sites with any of the DTI metrics. The atlas-based ROI analysis showed that the mean reproducibility errors largely remained in the 2-4% range for FA and AD and 2-6% for MD and RD, averaged across ROIs. Our results show reproducibility values comparable to those reported in studies using a smaller number of MRI scanners, slightly different DTI protocols and mostly younger populations. We therefore show that the acquisition and analysis protocols used are appropriate for multi-site experimental scenarios. Copyright © 2014 Elsevier Inc. All rights reserved.

Update on the magnetic resonance imaging core of the Alzheimer's disease neuroimaging initiative.

PubMed

Jack, Clifford R; Bernstein, Matt A; Borowski, Bret J; Gunter, Jeffrey L; Fox, Nick C; Thompson, Paul M; Schuff, Norbert; Krueger, Gunnar; Killiany, Ronald J; Decarli, Charles S; Dale, Anders M; Carmichael, Owen W; Tosun, Duygu; Weiner, Michael W

2010-05-01

Functions of the Alzheimer's Disease Neuroimaging Initiative (ADNI) magnetic resonance imaging (MRI) core fall into three categories: (1) those of the central MRI core laboratory at Mayo Clinic, Rochester, Minnesota, needed to generate high quality MRI data in all subjects at each time point; (2) those of the funded ADNI MRI core imaging analysis groups responsible for analyzing the MRI data; and (3) the joint function of the entire MRI core in designing and problem solving MR image acquisition, pre-processing, and analyses methods. The primary objective of ADNI was and continues to be improving methods for clinical trials in Alzheimer's disease. Our approach to the present ("ADNI-GO") and future ("ADNI-2," if funded) MRI protocol will be to maintain MRI methodological consistency in the previously enrolled "ADNI-1" subjects who are followed up longitudinally in ADNI-GO and ADNI-2. We will modernize and expand the MRI protocol for all newly enrolled ADNI-GO and ADNI-2 subjects. All newly enrolled subjects will be scanned at 3T with a core set of three sequence types: 3D T1-weighted volume, FLAIR, and a long TE gradient echo volumetric acquisition for micro hemorrhage detection. In addition to this core ADNI-GO and ADNI-2 protocol, we will perform vendor-specific pilot sub-studies of arterial spin-labeling perfusion, resting state functional connectivity, and diffusion tensor imaging. One of these sequences will be added to the core protocol on systems from each MRI vendor. These experimental sub-studies are designed to demonstrate the feasibility of acquiring useful data in a multicenter (but single vendor) setting for these three emerging MRI applications. Copyright 2010 The Alzheimer

Preliminary experience with a novel method of three-dimensional co-registration of prostate cancer digital histology and in vivo multiparametric MRI.

PubMed

Orczyk, C; Rusinek, H; Rosenkrantz, A B; Mikheev, A; Deng, F-M; Melamed, J; Taneja, S S

2013-12-01

To assess a novel method of three-dimensional (3D) co-registration of prostate cancer digital histology and in-vivo multiparametric magnetic resonance imaging (mpMRI) image sets for clinical usefulness. A software platform was developed to achieve 3D co-registration. This software was prospectively applied to three patients who underwent radical prostatectomy. Data comprised in-vivo mpMRI [T2-weighted, dynamic contrast-enhanced weighted images (DCE); apparent diffusion coefficient (ADC)], ex-vivo T2-weighted imaging, 3D-rebuilt pathological specimen, and digital histology. Internal landmarks from zonal anatomy served as reference points for assessing co-registration accuracy and precision. Applying a method of deformable transformation based on 22 internal landmarks, a 1.6 mm accuracy was reached to align T2-weighted images and the 3D-rebuilt pathological specimen, an improvement over rigid transformation of 32% (p = 0.003). The 22 zonal anatomy landmarks were more accurately mapped using deformable transformation than rigid transformation (p = 0.0008). An automatic method based on mutual information, enabled automation of the process and to include perfusion and diffusion MRI images. Evaluation of co-registration accuracy using the volume overlap index (Dice index) met clinically relevant requirements, ranging from 0.81-0.96 for sequences tested. Ex-vivo images of the specimen did not significantly improve co-registration accuracy. This preliminary analysis suggests that deformable transformation based on zonal anatomy landmarks is accurate in the co-registration of mpMRI and histology. Including diffusion and perfusion sequences in the same 3D space as histology is essential further clinical information. The ability to localize cancer in 3D space may improve targeting for image-guided biopsy, focal therapy, and disease quantification in surveillance protocols. Copyright © 2013 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

Image processing and Quality Control for the first 10,000 brain imaging datasets from UK Biobank.

PubMed

Alfaro-Almagro, Fidel; Jenkinson, Mark; Bangerter, Neal K; Andersson, Jesper L R; Griffanti, Ludovica; Douaud, Gwenaëlle; Sotiropoulos, Stamatios N; Jbabdi, Saad; Hernandez-Fernandez, Moises; Vallee, Emmanuel; Vidaurre, Diego; Webster, Matthew; McCarthy, Paul; Rorden, Christopher; Daducci, Alessandro; Alexander, Daniel C; Zhang, Hui; Dragonu, Iulius; Matthews, Paul M; Miller, Karla L; Smith, Stephen M

2018-02-01

UK Biobank is a large-scale prospective epidemiological study with all data accessible to researchers worldwide. It is currently in the process of bringing back 100,000 of the original participants for brain, heart and body MRI, carotid ultrasound and low-dose bone/fat x-ray. The brain imaging component covers 6 modalities (T1, T2 FLAIR, susceptibility weighted MRI, Resting fMRI, Task fMRI and Diffusion MRI). Raw and processed data from the first 10,000 imaged subjects has recently been released for general research access. To help convert this data into useful summary information we have developed an automated processing and QC (Quality Control) pipeline that is available for use by other researchers. In this paper we describe the pipeline in detail, following a brief overview of UK Biobank brain imaging and the acquisition protocol. We also describe several quantitative investigations carried out as part of the development of both the imaging protocol and the processing pipeline. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Comparison of neonatal MRI examinations with and without an MR-compatible incubator: advantages in examination feasibility and clinical decision-making.

PubMed

Rona, Z; Klebermass, K; Cardona, F; Czaba, C D; Brugger, P C; Weninger, M; Pollak, A; Prayer, D

2010-09-01

To assess the utility of an MRI-compatible incubator (INC) by comparing. In a retrospective study, the clinical and radiological aspects of 129 neonatal MRI examinations during a 3 year period were analyzed. Routine protocols including fast spin-echo T2-weighted (w) sequences, axial T1w, Gradient-echo, diffusion sequences, and 3D T1 gradient-echo sequences were performed routinely, angiography and spectroscopy were added in some cases. Diffusion-tensor imaging was done in 50% of the babies examined in the INC and 26% without INC. Sequences, adapted from fetal MR-protocols were done in infants younger than 32 gestational weeks. Benefit from MR-information with respect to further management was evaluated. The number of the examinations increased (30-99), while the mean age (43-38, 8 weeks of gestational age) and weight (3308-2766 g) decreased significantly with the use of the MR-compatible incubator. The mean imaging time (34, 43-30, 29 min) decreased, with a mean of one additionally performed sequence in the INC group. All infants received sedatives according to our anaesthetic protocol preceding imaging, but a repeated dose was never necessary (10% without INC) using the INC. Regarding all cases, MR-based changes in clinical management were initiated in 58%, while in 57% of cases the initial ultrasound diagnosis was changed or further specified. The use of the INC enables the MR access of unstable infants with suspect CNS problems to the management, of whom is improved by MR information to significantly higher percentage, than without INC. Copyright (c) 2010 European Paediatric Neurology Society. Published by Elsevier Ltd. All rights reserved.

Novel Diffusion-Weighted MRI for High-Grade Prostate Cancer Detection

DTIC Science & Technology

2017-10-01

AWARD NUMBER: W81XWH-15-1-0346 TITLE: Novel Diffusion-Weighted MRI for High -Grade Prostate Cancer Detection PRINCIPAL INVESTIGATOR: Michael Abern...Unlimited The views, opinions and/or findings contained in this report are those of the author(s) and should not be construed as an official Department of...Diffusion-Weighted MRI for High -Grade Prostate Cancer Detection 5a. CONTRACT NUMBER 5b. GRANT NUMBER W81XWH-15-1-0346 5c. PROGRAM ELEMENT NUMBER 6

Diffusion Weighted/Tensor Imaging, Functional MRI and Perfusion Weighted Imaging in Glioblastoma-Foundations and Future.

PubMed

Salama, Gayle R; Heier, Linda A; Patel, Praneil; Ramakrishna, Rohan; Magge, Rajiv; Tsiouris, Apostolos John

2017-01-01

In this article, we review the basics of diffusion tensor imaging and functional MRI, their current utility in preoperative neurosurgical mapping, and their limitations. We also discuss potential future applications, including implementation of resting state functional MRI. We then discuss perfusion and diffusion-weighted imaging and their application in advanced neuro-oncologic practice. We explain how these modalities can be helpful in guiding surgical biopsies and differentiating recurrent tumor from treatment related changes.

Diffusion Weighted/Tensor Imaging, Functional MRI and Perfusion Weighted Imaging in Glioblastoma—Foundations and Future

PubMed Central

Salama, Gayle R.; Heier, Linda A.; Patel, Praneil; Ramakrishna, Rohan; Magge, Rajiv; Tsiouris, Apostolos John

2018-01-01

In this article, we review the basics of diffusion tensor imaging and functional MRI, their current utility in preoperative neurosurgical mapping, and their limitations. We also discuss potential future applications, including implementation of resting state functional MRI. We then discuss perfusion and diffusion-weighted imaging and their application in advanced neuro-oncologic practice. We explain how these modalities can be helpful in guiding surgical biopsies and differentiating recurrent tumor from treatment related changes. PMID:29403420

Ultra-high field upper extremity peripheral nerve and non-contrast enhanced vascular imaging

PubMed Central

Raval, Shailesh B.; Britton, Cynthia A.; Zhao, Tiejun; Krishnamurthy, Narayanan; Santini, Tales; Gorantla, Vijay S.; Ibrahim, Tamer S.

2017-01-01

Objective The purpose of this study was to explore the efficacy of Ultra-high field [UHF] 7 Tesla [T] MRI as compared to 3T MRI in non-contrast enhanced [nCE] imaging of structural anatomy in the elbow, forearm, and hand [upper extremity]. Materials and method A wide range of sequences including T1 weighted [T1] volumetric interpolate breath-hold exam [VIBE], T2 weighted [T2] double-echo steady state [DESS], susceptibility weighted imaging [SWI], time-of-flight [TOF], diffusion tensor imaging [DTI], and diffusion spectrum imaging [DSI] were optimized and incorporated with a radiofrequency [RF] coil system composed of a transverse electromagnetic [TEM] transmit coil combined with an 8-channel receive-only array for 7T upper extremity [UE] imaging. In addition, Siemens optimized protocol/sequences were used on a 3T scanner and the resulting images from T1 VIBE and T2 DESS were compared to that obtained at 7T qualitatively and quantitatively [SWI was only qualitatively compared]. DSI studio was utilized to identify nerves based on analysis of diffusion weighted derived fractional anisotropy images. Images of forearm vasculature were extracted using a paint grow manual segmentation method based on MIPAV [Medical Image Processing, Analysis, and Visualization]. Results High resolution and high quality signal-to-noise ratio [SNR] and contrast-to-noise ratio [CNR]—images of the hand, forearm, and elbow were acquired with nearly homogeneous 7T excitation. Measured [performed on the T1 VIBE and T2 DESS sequences] SNR and CNR values were almost doubled at 7T vs. 3T. Cartilage, synovial fluid and tendon structures could be seen with higher clarity in the 7T T1 and T2 weighted images. SWI allowed high resolution and better quality imaging of large and medium sized arteries and veins, capillary networks and arteriovenous anastomoses at 7T when compared to 3T. 7T diffusion weighted sequence [not performed at 3T] demonstrates that the forearm nerves are clearly delineated by fiber tractography. The proper digital palmar arteries and superficial palmar arch could also be clearly visualized using TOF nCE 7T MRI. Conclusion Ultra-high resolution neurovascular imaging in upper extremities is possible at 7T without use of renal toxic intravenous contrast. 7T MRI can provide superior peripheral nerve [based on fiber anisotropy and diffusion coefficient parameters derived from diffusion tensor/spectrum imaging] and vascular [nCE MRA and vessel segmentation] imaging. PMID:28662061

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

PubMed

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).

DIFFUSION-WEIGHTED IMAGING OF THE LIVER: TECHNIQUES AND APPLICATIONS

PubMed Central

Lewis, Sara; Dyvorne, Hadrien; Cui, Yong; Taouli, Bachir

2014-01-01

SYNOPSIS Diffusion weighted MRI (DWI) is a technique that assesses the cellularity, tortuosity of the extracellular/extravascular space and cell membrane density based upon differences in water proton mobility in tissues. The strength of the diffusion weighting is reflected by the b-value. DWI using several b-values enables quantification of the apparent diffusion coefficient (ADC). DWI is increasingly employed in liver imaging for multiple reasons: it can add useful qualitative and quantitative information to conventional imaging sequences, it is acquired relatively quickly, it is easily incorporated into existing clinical protocols, and it is a non-contrast technique. DWI is useful for focal liver lesion detection and characterization, for the assessment of post-treatment tumor response and for evaluation of diffuse liver disease. ADC quantification can be used to characterize lesions as cystic/necrotic or solid and for predicting tumor response to therapy. Advanced diffusion methods such as IVIM (intravoxel incoherent motion) may have potential for detection, staging and evaluation of the progression of liver fibrosis and for liver lesion characterization. The lack of standardization of DWI technique including choice of b-values and sequence parameters has somewhat limited its widespread adoption. PMID:25086935

Diffusion Tensor Imaging of Heterotopia: Changes of Fractional Anisotropy during Radial Migration of Neurons

PubMed Central

Kim, Jinna

2010-01-01

Purpose Diffusion tensor imaging provides better understanding of pathophysiology of congenital anomalies, involving central nervous system. This study was aimed to specify the pathogenetic mechanism of heterotopia, proved by diffusion tensor imaging, and establish new findings of heterotopia on fractional anisotropy maps. Materials and Methods Diffusion-weighted imaging data from 11 patients (M : F = 7 : 4, aged from 1 to 22 years, mean = 12.3 years) who visited the epilepsy clinic and received a routine seizure protocol MRI exam were retrospectively analyzed. Fractional anisotropy (FA) maps were generated from diffusion tensor imaging of 11 patients with heterotopia. Regions of interests (ROI) were placed in cerebral cortex, heterotopic gray matter and deep gray matter, including putamen. ANOVA analysis was performed for comparison of different gray matter tissues. Results Heterotopic gray matter showed signal intensities similar to normal gray matter on T1 and T2 weighted MRI. The measured FA of heterotopic gray matter was higher than that of cortical gray matter (0.236 ± 0.011 vs. 0.169 ± 0.015, p < 0.01, one way ANOVA), and slightly lower than that of deep gray matter (0.236 ± 0.011 vs. 0.259 ± 0.016, p < 0.01). Conclusion Increased FA of heterotopic gray matter suggests arrested neuron during radial migration and provides better understanding of neurodevelopment. PMID:20499428

Hybrid [¹⁸F]-FDG PET/MRI including non-Gaussian diffusion-weighted imaging (DWI): preliminary results in non-small cell lung cancer (NSCLC).

PubMed

Heusch, Philipp; Köhler, Jens; Wittsack, Hans-Joerg; Heusner, Till A; Buchbender, Christian; Poeppel, Thorsten D; Nensa, Felix; Wetter, Axel; Gauler, Thomas; Hartung, Verena; Lanzman, Rotem S

2013-11-01

To assess the feasibility of non-Gaussian DWI as part of a FDG-PET/MRI protocol in patients with histologically proven non-small cell lung cancer. 15 consecutive patients with histologically proven NSCLC (mean age 61 ± 11 years) were included in this study and underwent whole-body FDG-PET/MRI following whole-body FDG-PET/CT. As part of the whole-body FDG-PET/MRI protocol, an EPI-sequence with 5 b-values (0, 100, 500, 1000 and 2000 s/mm(2)) was acquired for DWI of the thorax during free-breathing. Volume of interest (VOI) measurements were performed to determine the maximum and mean standardized uptake value (SUV(max); SUV(mean)). A region of interest (ROI) was manually drawn around the tumor on b=0 images and then transferred to the corresponding parameter maps to assess ADC(mono), D(app) and K(app). To assess the goodness of the mathematical fit R(2) was calculated for monoexponential and non-Gaussian analysis. Spearman's correlation coefficients were calculated to compare SUV values and diffusion coefficients. A Student's t-test was performed to compare the monoexponential and non-Gaussian diffusion fitting (R(2)). T staging was equal between FDG-PET/CT and FDG-PET/MRI in 12 of 15 patients. For NSCLC, mean ADC(mono) was 2.11 ± 1.24 × 10(-3) mm(2)/s, Dapp was 2.46 ± 1.29 × 10(-3) mm(2)/s and mean Kapp was 0.70 ± 0.21. The non-Gaussian diffusion analysis (R(2)=0.98) provided a significantly better mathematical fitting to the DWI signal decay than the monoexponetial analysis (R(2)=0.96) (p<0.001). SUV(max) and SUV(mean) of NSCLC was 13.5 ± 7.6 and 7.9 ± 4.3 for FDG-PET/MRI. ADC(mono) as well as Dapp exhibited a significant inverse correlation with the SUV(max) (ADC(mono): R=-0.67; p<0.01; Dapp: R=-0.69; p<0.01) as well as with SUV(mean) assessed by FDG-PET/MRI (ADC(mono): R=-0.66; p<0.01; Dapp: R=-0.69; p<0.01). Furthermore, Kapp exhibited a significant correlation with SUV(max) (R=0.72; p<0.05) and SUV(mean) as assessed by FDG-PET/MRI (R=0.71; p<0.005). Simultaneous PET and non-Gaussian diffusion acquisitions are feasible. Non-Gaussian diffusion parameters show a good correlation with SUV and might provide additional information beyond monoexponential ADC, especially as non-Gaussian diffusion exhibits better mathematical fitting to the decay of the diffusion signal than monoexponential DWI. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Enhanced multi-protocol analysis via intelligent supervised embedding (EMPrAvISE): detecting prostate cancer on multi-parametric MRI

NASA Astrophysics Data System (ADS)

Viswanath, Satish; Bloch, B. Nicholas; Chappelow, Jonathan; Patel, Pratik; Rofsky, Neil; Lenkinski, Robert; Genega, Elizabeth; Madabhushi, Anant

2011-03-01

Currently, there is significant interest in developing methods for quantitative integration of multi-parametric (structural, functional) imaging data with the objective of building automated meta-classifiers to improve disease detection, diagnosis, and prognosis. Such techniques are required to address the differences in dimensionalities and scales of individual protocols, while deriving an integrated multi-parametric data representation which best captures all disease-pertinent information available. In this paper, we present a scheme called Enhanced Multi-Protocol Analysis via Intelligent Supervised Embedding (EMPrAvISE); a powerful, generalizable framework applicable to a variety of domains for multi-parametric data representation and fusion. Our scheme utilizes an ensemble of embeddings (via dimensionality reduction, DR); thereby exploiting the variance amongst multiple uncorrelated embeddings in a manner similar to ensemble classifier schemes (e.g. Bagging, Boosting). We apply this framework to the problem of prostate cancer (CaP) detection on 12 3 Tesla pre-operative in vivo multi-parametric (T2-weighted, Dynamic Contrast Enhanced, and Diffusion-weighted) magnetic resonance imaging (MRI) studies, in turn comprising a total of 39 2D planar MR images. We first align the different imaging protocols via automated image registration, followed by quantification of image attributes from individual protocols. Multiple embeddings are generated from the resultant high-dimensional feature space which are then combined intelligently to yield a single stable solution. Our scheme is employed in conjunction with graph embedding (for DR) and probabilistic boosting trees (PBTs) to detect CaP on multi-parametric MRI. Finally, a probabilistic pairwise Markov Random Field algorithm is used to apply spatial constraints to the result of the PBT classifier, yielding a per-voxel classification of CaP presence. Per-voxel evaluation of detection results against ground truth for CaP extent on MRI (obtained by spatially registering pre-operative MRI with available whole-mount histological specimens) reveals that EMPrAvISE yields a statistically significant improvement (AUC=0.77) over classifiers constructed from individual protocols (AUC=0.62, 0.62, 0.65, for T2w, DCE, DWI respectively) as well as one trained using multi-parametric feature concatenation (AUC=0.67).

Diffusion Tensor Imaging and Resting-State Functional MRI-Scanning in 5- and 6-Year-Old Children: Training Protocol and Motion Assessment

PubMed Central

Theys, Catherine; Wouters, Jan; Ghesquière, Pol

2014-01-01

Advanced Magnetic Resonance Imaging (MRI) techniques such as Diffusion Tensor Imaging (DTI) and resting-state functional MRI (rfMRI) are widely used to study structural and functional neural connectivity. However, as these techniques are highly sensitive to motion artifacts and require a considerable amount of time for image acquisition, successful acquisition of these images can be challenging to complete with certain populations. This is especially true for young children. This paper describes a new approach termed the ‘submarine protocol’, designed to prepare 5- and 6-year-old children for advanced MRI scanning. The submarine protocol aims to ensure that successful scans can be acquired in a time- and resource-efficient manner, without the need for sedation. This manuscript outlines the protocol and details its outcomes, as measured through the number of children who completed the scanning procedure and analysis of the degree of motion present in the acquired images. Seventy-six children aged between 5.8 and 6.9 years were trained using the submarine protocol and subsequently underwent DTI and rfMRI scanning. After completing the submarine protocol, 75 of the 76 children (99%) completed their DTI-scan and 72 children (95%) completed the full 35-minute scan session. Results of diffusion data, acquired in 75 children, showed that the motion in 60 of the scans (80%) did not exceed the threshold for excessive motion. In the rfMRI scans, this was the case for 62 of the 71 scans (87%). When placed in the context of previous studies, the motion data of the 5- and 6-year-old children reported here were as good as, or better than those previously reported for groups of older children (i.e., 8-year-olds). Overall, this study shows that the submarine protocol can be used successfully to acquire DTI and rfMRI scans in 5 and 6-year-old children, without the need for sedation or lengthy training procedures. PMID:24718364

Detailed magnetic resonance imaging features of a case series of primary gliosarcoma.

PubMed

Sampaio, Luísa; Linhares, Paulo; Fonseca, José

2017-12-01

Objective We aimed to characterise the magnetic resonance imaging (MRI) features of a case series of primary gliosarcoma, with the inclusion of diffusion-weighted imaging and perfusion imaging with dynamic susceptibility contrast MRI. Materials and methods We conducted a retrospective study of cases of primary gliosarcoma from the Pathology Department database from January 2006 to December 2014. Clinical and demographic data were obtained. Two neuroradiologists, blinded to diagnosis, assessed tumour location, signal intensity in T1 and T2-weighted images, pattern of enhancement, diffusion-weighted imaging and dynamic susceptibility contrast MRI studies on preoperative MRI. Results Seventeen patients with primary gliosarcomas had preoperative MRI study: seven men and 10 women, with a mean age of 59 years (range 27-74). All lesions were well demarcated, supratentorial and solitary (frontal n = 5, temporal n = 4, parietal n = 3); 13 tumours abutted the dural surface (8/13 with dural enhancement); T1 and T2-weighted imaging patterns were heterogeneous and the majority of lesions (12/17) showed a rim-like enhancement pattern with focal nodularities/irregular thickness. Restricted diffusion (mean apparent diffusion coefficient values 0.64 × 10 -3 mm 2 /s) in the more solid/thick components was present in eight out of 11 patients with diffusion-weighted imaging study. Dynamic susceptibility contrast MRI study ( n = 8) consistently showed hyperperfusion in non-necrotic/cystic components on relative cerebral volume maps. Conclusions The main distinguishing features of primary gliosarcoma are supratentorial and peripheral location, well-defined boundaries and a rim-like pattern of enhancement with an irregular thick wall. Diffusion-weighted imaging and relative cerebral volume map analysis paralleled primary gliosarcoma with high-grade gliomas, thus proving helpful in differential diagnosis.

Artifact correction in diffusion MRI of non-human primate brains on a clinical 3T scanner.

PubMed

Zhang, Xiaodong; Kirsch, John E; Zhong, Xiaodong

2016-02-01

Smearing artifacts were observed and investigated in diffusion tensor imaging (DTI) studies of macaque monkeys on a clinical whole-body 3T scanner. Four adult macaques were utilized to evaluate DTI artifacts. DTI images were acquired with a single-shot echo-planar imaging (EPI) sequence using a parallel imaging technique. The smearing artifacts observed on the diffusion-weighted images and fractional anisotropy maps were caused by the incomplete fat suppression due to the irregular macaque frontal skull geometry and anatomy. The artifact can be reduced substantially using a novel three-dimensional (3D) shimming procedure. The smearing artifacts observed on diffusion weighted images and fractional anisotropy (FA) maps of macaque brains can be reduced substantially using a robust 3D shimming approach. The DTI protocol combined with the shimming procedure could be a robust approach to examine brain connectivity and white matter integrity of non-human primates using a conventional clinical setting. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

A fast screening protocol for carotid plaques imaging using 3D multi-contrast MRI without contrast agent.

PubMed

Zhang, Na; Zhang, Lei; Yang, Qi; Pei, Anqi; Tong, Xiaoxin; Chung, Yiu-Cho; Liu, Xin

2017-06-01

To implement a fast (~15min) MRI protocol for carotid plaque screening using 3D multi-contrast MRI sequences without contrast agent on a 3Tesla MRI scanner. 7 healthy volunteers and 25 patients with clinically confirmed transient ischemic attack or suspected cerebrovascular ischemia were included in this study. The proposed protocol, including 3D T1-weighted and T2-weighted SPACE (variable-flip-angle 3D turbo spin echo), and T1-weighted magnetization prepared rapid acquisition gradient echo (MPRAGE) was performed first and was followed by 2D T1-weighted and T2-weighted turbo spin echo, and post-contrast T1-weighted SPACE sequences. Image quality, number of plaques, and vessel wall thicknesses measured at the intersection of the plaques were evaluated and compared between sequences. Average examination time of the proposed protocol was 14.6min. The average image quality scores of 3D T1-weighted, T2-weighted SPACE, and T1-weighted magnetization prepared rapid acquisition gradient echo were 3.69, 3.75, and 3.48, respectively. There was no significant difference in detecting the number of plaques and vulnerable plaques using pre-contrast 3D images with or without post-contrast T1-weighted SPACE. The 3D SPACE and 2D turbo spin echo sequences had excellent agreement (R=0.96 for T1-weighted and 0.98 for T2-weighted, p<0.001) regarding vessel wall thickness measurements. The proposed protocol demonstrated the feasibility of attaining carotid plaque screening within a 15-minute scan, which provided sufficient anatomical coverage and critical diagnostic information. This protocol offers the potential for rapid and reliable screening for carotid plaques without contrast agent. Copyright © 2016. Published by Elsevier Inc.

Multi-site Study of Diffusion Metric Variability: Characterizing the Effects of Site, Vendor, Field Strength, and Echo Time using the Histogram Distance.

PubMed

Helmer, K G; Chou, M-C; Preciado, R I; Gimi, B; Rollins, N K; Song, A; Turner, J; Mori, S

2016-02-27

MRI-based multi-site trials now routinely include some form of diffusion-weighted imaging (DWI) in their protocol. These studies can include data originating from scanners built by different vendors, each with their own set of unique protocol restrictions, including restrictions on the number of available gradient directions, whether an externally-generated list of gradient directions can be used, and restrictions on the echo time (TE). One challenge of multi-site studies is to create a common imaging protocol that will result in a reliable and accurate set of diffusion metrics. The present study describes the effect of site, scanner vendor, field strength, and TE on two common metrics: the first moment of the diffusion tensor field (mean diffusivity, MD), and the fractional anisotropy (FA). We have shown in earlier work that ROI metrics and the mean of MD and FA histograms are not sufficiently sensitive for use in site characterization. Here we use the distance between whole brain histograms of FA and MD to investigate within- and between-site effects. We concluded that the variability of DTI metrics due to site, vendor, field strength, and echo time could influence the results in multi-center trials and that histogram distance is sensitive metrics for each of these variables.

The potential of multiparametric MRI of the breast

PubMed Central

Pinker, Katja; Helbich, Thomas H

2017-01-01

MRI is an essential tool in breast imaging, with multiple established indications. Dynamic contrast-enhanced MRI (DCE-MRI) is the backbone of any breast MRI protocol and has an excellent sensitivity and good specificity for breast cancer diagnosis. DCE-MRI provides high-resolution morphological information, as well as some functional information about neoangiogenesis as a tumour-specific feature. To overcome limitations in specificity, several other functional MRI parameters have been investigated and the application of these combined parameters is defined as multiparametric MRI (mpMRI) of the breast. MpMRI of the breast can be performed at different field strengths (1.5–7 T) and includes both established (diffusion-weighted imaging, MR spectroscopic imaging) and novel MRI parameters (sodium imaging, chemical exchange saturation transfer imaging, blood oxygen level-dependent MRI), as well as hybrid imaging with positron emission tomography (PET)/MRI and different radiotracers. Available data suggest that multiparametric imaging using different functional MRI and PET parameters can provide detailed information about the underlying oncogenic processes of cancer development and progression and can provide additional specificity. This article will review the current and emerging functional parameters for mpMRI of the breast for improved diagnostic accuracy in breast cancer. PMID:27805423

Effectiveness of a Rapid Lumbar Spine MRI Protocol Using 3D T2-Weighted SPACE Imaging Versus a Standard Protocol for Evaluation of Degenerative Changes of the Lumbar Spine.

PubMed

Sayah, Anousheh; Jay, Ann K; Toaff, Jacob S; Makariou, Erini V; Berkowitz, Frank

2016-09-01

Reducing lumbar spine MRI scanning time while retaining diagnostic accuracy can benefit patients and reduce health care costs. This study compares the effectiveness of a rapid lumbar MRI protocol using 3D T2-weighted sampling perfection with application-optimized contrast with different flip-angle evolutions (SPACE) sequences with a standard MRI protocol for evaluation of lumbar spondylosis. Two hundred fifty consecutive unenhanced lumbar MRI examinations performed at 1.5 T were retrospectively reviewed. Full, rapid, and complete versions of each examination were interpreted for spondylotic changes at each lumbar level, including herniations and neural compromise. The full examination consisted of sagittal T1-weighted, T2-weighted turbo spin-echo (TSE), and STIR sequences; and axial T1- and T2-weighted TSE sequences (time, 18 minutes 40 seconds). The rapid examination consisted of sagittal T1- and T2-weighted SPACE sequences, with axial SPACE reformations (time, 8 minutes 46 seconds). The complete examination consisted of the full examination plus the T2-weighted SPACE sequence. Sensitivities and specificities of the full and rapid examinations were calculated using the complete study as the reference standard. The rapid and full studies had sensitivities of 76.0% and 69.3%, with specificities of 97.2% and 97.9%, respectively, for all degenerative processes. Rapid and full sensitivities were 68.7% and 66.3% for disk herniation, 85.2% and 81.5% for canal compromise, 82.9% and 69.1% for lateral recess compromise, and 76.9% and 69.7% for foraminal compromise, respectively. Isotropic SPACE T2-weighted imaging provides high-quality imaging of lumbar spondylosis, with multiplanar reformatting capability. Our SPACE-based rapid protocol had sensitivities and specificities for herniations and neural compromise comparable to those of the protocol without SPACE. This protocol fits within a 15-minute slot, potentially reducing costs and discomfort for a large subgroup of patients.

Ameliorating slice gaps in multislice magnetic resonance images: an interpolation scheme.

PubMed

Kashou, Nasser H; Smith, Mark A; Roberts, Cynthia J

2015-01-01

Standard two-dimension (2D) magnetic resonance imaging (MRI) clinical acquisition protocols utilize orthogonal plane images which contain slice gaps (SG). The purpose of this work is to introduce a novel interpolation method for these orthogonal plane MRI 2D datasets. Three goals can be achieved: (1) increasing the resolution based on a priori knowledge of scanning protocol, (2) ameliorating the loss of data as a result of SG and (3) reconstructing a three-dimension (3D) dataset from 2D images. MRI data was collected using a 3T GE scanner and simulated using Matlab. The procedure for validating the MRI data combination algorithm was performed using a Shepp-Logan and a Gaussian phantom in both 2D and 3D of varying matrix sizes (64-512), as well as on one MRI dataset of a human brain and on an American College of Radiology magnetic resonance accreditation phantom. The squared error and mean squared error were computed in comparing this scheme to common interpolating functions employed in MR consoles and workstations. The mean structure similarity matrix was computed in 2D as a means of qualitative image assessment. Additionally, MRI scans were used for qualitative assessment of the method. This new scheme was consistently more accurate than upsampling each orientation separately and averaging the upsampled data. An efficient new interpolation approach to resolve SG was developed. This scheme effectively fills in the missing data points by using orthogonal plane images. To date, there have been few attempts to combine the information of three MRI plane orientations using brain images. This has specific applications for clinical MRI, functional MRI, diffusion-weighted imaging/diffusion tensor imaging and MR angiography where 2D slice acquisition are used. In these cases, the 2D data can be combined using our method in order to obtain 3D volume.

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

PubMed

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.

The brain imaging data structure, a format for organizing and describing outputs of neuroimaging experiments.

PubMed

Gorgolewski, Krzysztof J; Auer, Tibor; Calhoun, Vince D; Craddock, R Cameron; Das, Samir; Duff, Eugene P; Flandin, Guillaume; Ghosh, Satrajit S; Glatard, Tristan; Halchenko, Yaroslav O; Handwerker, Daniel A; Hanke, Michael; Keator, David; Li, Xiangrui; Michael, Zachary; Maumet, Camille; Nichols, B Nolan; Nichols, Thomas E; Pellman, John; Poline, Jean-Baptiste; Rokem, Ariel; Schaefer, Gunnar; Sochat, Vanessa; Triplett, William; Turner, Jessica A; Varoquaux, Gaël; Poldrack, Russell A

2016-06-21

The development of magnetic resonance imaging (MRI) techniques has defined modern neuroimaging. Since its inception, tens of thousands of studies using techniques such as functional MRI and diffusion weighted imaging have allowed for the non-invasive study of the brain. Despite the fact that MRI is routinely used to obtain data for neuroscience research, there has been no widely adopted standard for organizing and describing the data collected in an imaging experiment. This renders sharing and reusing data (within or between labs) difficult if not impossible and unnecessarily complicates the application of automatic pipelines and quality assurance protocols. To solve this problem, we have developed the Brain Imaging Data Structure (BIDS), a standard for organizing and describing MRI datasets. The BIDS standard uses file formats compatible with existing software, unifies the majority of practices already common in the field, and captures the metadata necessary for most common data processing operations.

The brain imaging data structure, a format for organizing and describing outputs of neuroimaging experiments

PubMed Central

Gorgolewski, Krzysztof J.; Auer, Tibor; Calhoun, Vince D.; Craddock, R. Cameron; Das, Samir; Duff, Eugene P.; Flandin, Guillaume; Ghosh, Satrajit S.; Glatard, Tristan; Halchenko, Yaroslav O.; Handwerker, Daniel A.; Hanke, Michael; Keator, David; Li, Xiangrui; Michael, Zachary; Maumet, Camille; Nichols, B. Nolan; Nichols, Thomas E.; Pellman, John; Poline, Jean-Baptiste; Rokem, Ariel; Schaefer, Gunnar; Sochat, Vanessa; Triplett, William; Turner, Jessica A.; Varoquaux, Gaël; Poldrack, Russell A.

2016-01-01

The development of magnetic resonance imaging (MRI) techniques has defined modern neuroimaging. Since its inception, tens of thousands of studies using techniques such as functional MRI and diffusion weighted imaging have allowed for the non-invasive study of the brain. Despite the fact that MRI is routinely used to obtain data for neuroscience research, there has been no widely adopted standard for organizing and describing the data collected in an imaging experiment. This renders sharing and reusing data (within or between labs) difficult if not impossible and unnecessarily complicates the application of automatic pipelines and quality assurance protocols. To solve this problem, we have developed the Brain Imaging Data Structure (BIDS), a standard for organizing and describing MRI datasets. The BIDS standard uses file formats compatible with existing software, unifies the majority of practices already common in the field, and captures the metadata necessary for most common data processing operations. PMID:27326542

Reticular Appearance on Gadolinium-enhanced T1- and Diffusion-weighted MRI, and Low Apparent Diffusion Coefficient Values in Microcystic Meningioma Cysts.

PubMed

Terada, Yukinori; Toda, Hiroki; Okumura, Ryosuke; Ikeda, Naokado; Yuba, Yoshiaki; Katayama, Toshiro; Iwasaki, Koichi

2018-03-01

Microcystic meningioma, a rare meningioma subtype, can present diagnostic difficulty. We aimed to investigate the historadiological properties of microcystic meningioma using conventional magnetic resonance imaging (MRI) and diffusion-weighted imaging (DWI) analysis. We retrospectively analyzed conventional MRI and DWI results of six microcystic meningioma cases by examining their appearance and determining their apparent diffusion coefficient (ADC) values. The ADC values of the intratumoral components were normalized with ADC values of the cerebrospinal fluid in the lateral ventricle (ADC ratios). As cystic formations are frequently associated with microcystic meningiomas, their MRI characteristics were compared with the imaging data from 11 cystic meningiomas of non-microcystic subtypes. We found that cysts in microcystic meningioma tended to have a reticular appearance on DWI, as they did on gadolinium-enhanced T1-weighted imaging. Additionally, these reticular cysts had significantly lower ADC ratios than microcystic non-reticular and non-microcystic cysts. These DWI characteristics likely reflect the histological properties of microcystic meningioma. A reticular appearance on gadolinium-enhanced T1-weighted MRI and DWI, and cyst formation with relatively low ADC values can be diagnostic markers of microcystic meningiomas.

Whole body MRI, including diffusion-weighted imaging in follow-up of patients with testicular cancer.

PubMed

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 regarding the activity of residual masses.

UK quantitative WB-DWI technical workgroup: consensus meeting recommendations on optimisation, quality control, processing and analysis of quantitative whole-body diffusion-weighted imaging for cancer.

PubMed

Barnes, Anna; Alonzi, Roberto; Blackledge, Matthew; Charles-Edwards, Geoff; Collins, David J; Cook, Gary; Coutts, Glynn; Goh, Vicky; Graves, Martin; Kelly, Charles; Koh, Dow-Mu; McCallum, Hazel; Miquel, Marc E; O'Connor, James; Padhani, Anwar; Pearson, Rachel; Priest, Andrew; Rockall, Andrea; Stirling, James; Taylor, Stuart; Tunariu, Nina; van der Meulen, Jan; Walls, Darren; Winfield, Jessica; Punwani, Shonit

2018-01-01

Application of whole body diffusion-weighted MRI (WB-DWI) for oncology are rapidly increasing within both research and routine clinical domains. However, WB-DWI as a quantitative imaging biomarker (QIB) has significantly slower adoption. To date, challenges relating to accuracy and reproducibility, essential criteria for a good QIB, have limited widespread clinical translation. In recognition, a UK workgroup was established in 2016 to provide technical consensus guidelines (to maximise accuracy and reproducibility of WB-MRI QIBs) and accelerate the clinical translation of quantitative WB-DWI applications for oncology. A panel of experts convened from cancer centres around the UK with subspecialty expertise in quantitative imaging and/or the use of WB-MRI with DWI. A formal consensus method was used to obtain consensus agreement regarding best practice. Questions were asked about the appropriateness or otherwise on scanner hardware and software, sequence optimisation, acquisition protocols, reporting, and ongoing quality control programs to monitor precision and accuracy and agreement on quality control. The consensus panel was able to reach consensus on 73% (255/351) items and based on consensus areas made recommendations to maximise accuracy and reproducibly of quantitative WB-DWI studies performed at 1.5T. The panel were unable to reach consensus on the majority of items related to quantitative WB-DWI performed at 3T. This UK Quantitative WB-DWI Technical Workgroup consensus provides guidance on maximising accuracy and reproducibly of quantitative WB-DWI for oncology. The consensus guidance can be used by researchers and clinicians to harmonise WB-DWI protocols which will accelerate clinical translation of WB-DWI-derived QIBs.

Functional localization of the human color center by decreased water displacement using diffusion-weighted fMRI.

PubMed

Williams, Rebecca J; Reutens, David C; Hocking, Julia

2015-11-01

Decreased water displacement following increased neural activity has been observed using diffusion-weighted functional MRI (DfMRI) at high b-values. The physiological mechanisms underlying the diffusion signal change may be unique from the standard blood oxygenation level-dependent (BOLD) contrast and closer to the source of neural activity. Whether DfMRI reflects neural activity more directly than BOLD outside the primary cerebral regions remains unclear. Colored and achromatic Mondrian visual stimuli were statistically contrasted to functionally localize the human color center Area V4 in neurologically intact adults. Spatial and temporal properties of DfMRI and BOLD activation were examined across regions of the visual cortex. At the individual level, DfMRI activation patterns showed greater spatial specificity to V4 than BOLD. The BOLD activation patterns were more prominent in the primary visual cortex than DfMRI, where activation was localized to the ventral temporal lobe. Temporally, the diffusion signal change in V4 and V1 both preceded the corresponding hemodynamic response, however the early diffusion signal change was more evident in V1. DfMRI may be of use in imaging applications implementing cognitive subtraction paradigms, and where highly precise individual functional localization is required.

Abbreviated MRI Protocols for Detecting Breast Cancer in Women with Dense Breasts.

PubMed

Chen, Shuang-Qing; Huang, Min; Shen, Yu-Ying; Liu, Chen-Lu; Xu, Chuan-Xiao

2017-01-01

To evaluate the validity of two abbreviated protocols (AP) of MRI in breast cancer screening of dense breast tissue. This was a retrospective study in 356 participants with dense breast tissue and negative mammography results. The study was approved by the Nanjing Medical University Ethics Committee. Patients were imaged with a full diagnostic protocol (FDP) of MRI. Two APs (AP-1 consisting of the first post-contrast subtracted [FAST] and maximum-intensity projection [MIP] images, and AP-2 consisting of AP-1 combined with diffusion-weighted imaging [DWI]) and FDP images were analyzed separately, and the sensitivities and specificities of breast cancer detection were calculated. Of the 356 women, 67 lesions were detected in 67 women (18.8%) by standard MR protocol, and histological examination revealed 14 malignant lesions and 53 benign lesions. The average interpretation time of AP-1 and AP-2 were 37 seconds and 54 seconds, respectively, while the average interpretation time of the FDP was 3 minutes and 25 seconds. The sensitivities of the AP-1, AP-2, and FDP were 92.9, 100, and 100%, respectively, and the specificities of the three MR protocols were 86.5, 95.0, and 96.8%, respectively. There was no significant difference among the three MR protocols in the diagnosis of breast cancer ( p > 0.05). However, the specificity of AP-1 was significantly lower than that of AP-2 ( p = 0.031) and FDP ( p = 0.035), while there was no difference between AP-2 and FDP ( p > 0.05). The AP may be efficient in the breast cancer screening of dense breast tissue. FAST and MIP images combined with DWI of MRI are helpful to improve the specificity of breast cancer detection.

A prospective study of diffusion weighted magnetic resonance imaging abnormalities in patients with cluster of seizures and status epilepticus.

PubMed

Jabeen, S A; Cherukuri, Pavankumar; Mridula, Rukmini; Harshavardhana, K R; Gaddamanugu, Padmaja; Sarva, Sailaja; Meena, A K; Borgohain, Rupam; Jyotsna Rani, Y

2017-04-01

To study the frequency, imaging characteristics, and clinical predictors for development of periictal diffusion weighted MRI abnormalities. We prospectively analyzed electro clinical and imaging characteristic of adult patients with cluster of seizures or status epilepticus between November 2013 and November 2015, in whom the diffusion weighted imaging was done within 24h after the end of last seizure (clinical or electrographic). There were thirty patients who fulfilled the inclusion and exclusion criteria. Twenty patients (66%) had periictal MRI abnormalities. Nine patients (34%) did not have any MRI abnormality. All the patients with PMA had abnormalities on diffusion weighted imaging (DWI). Hippocampal abnormalities were seen in nine (53%), perisylvian in two (11.7%), thalamic in five (30%), splenium involvement in two (11.7%) and cortical involvement (temporo-occipital, parieto-occipital, temporo-parietal, fronto-parietal and fronto-temporal) in sixteen (94.1%) patients. Complete reversal of DWI changes was noted in sixteen (80%) patients and four (20%) patients showed partial resolution of MRI abnormalities. Mean duration of seizures was significantly higher among patients with PMA (59.11+20.97h) compared to those without MRI changes (27.33+9.33h) (p<0.001). Diffusion abnormalities on MRI are common in patients with cluster of seizures and status epilepticus and were highly concordant with clinical semiology and EEG activity. Patients with longer duration of seizures/status were more likely to have PMA. Copyright © 2017 Elsevier B.V. All rights reserved.

Diffusion-Weighted Magnetic Resonance Imaging of Cholesteatoma Using PROPELLER at 1.5T: A Single-Centre Retrospective Study.

PubMed

Clarke, Sharon E; Mistry, Dipan; AlThubaiti, Talal; Khan, M Naeem; Morris, David; Bance, Manohar

2017-05-01

The purpose of this study was to evaluate the sensitivity, specificity, and positive and negative predictive values of the diffusion-weighted periodically rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) technique in the detection of cholesteatoma at our institution with surgical confirmation in all cases. A retrospective review of 21 consecutive patients who underwent diffusion-weighted PROPELLER magnetic resonance imaging (MRI) on a 1.5T MRI scanner prior to primary or revision/second-look surgery for suspected cholesteatoma from 2009-2012 was performed. Diffusion-weighted PROPELLER had a sensitivity of 75%, specificity of 60%, positive predictive value of 86%, and negative predictive value of 43%. In the 15 patients for whom the presence or absence of cholesteatoma was correctly predicted, there were 2 cases where the reported locations of diffusion restriction did not correspond to the location of the cholesteatoma observed at surgery. On the basis of our retrospective study, we conclude that diffusion-weighted PROPELLER MRI is not sufficiently accurate to replace second look surgery at our institution. Copyright © 2016 Canadian Association of Radiologists. Published by Elsevier Inc. All rights reserved.

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

PubMed

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.

Multi-site Study of Diffusion Metric Variability: Characterizing the Effects of Site, Vendor, Field Strength, and Echo Time using the Histogram Distance

PubMed Central

Helmer, K. G.; Chou, M-C.; Preciado, R. I.; Gimi, B.; Rollins, N. K.; Song, A.; Turner, J.; Mori, S.

2016-01-01

MRI-based multi-site trials now routinely include some form of diffusion-weighted imaging (DWI) in their protocol. These studies can include data originating from scanners built by different vendors, each with their own set of unique protocol restrictions, including restrictions on the number of available gradient directions, whether an externally-generated list of gradient directions can be used, and restrictions on the echo time (TE). One challenge of multi-site studies is to create a common imaging protocol that will result in a reliable and accurate set of diffusion metrics. The present study describes the effect of site, scanner vendor, field strength, and TE on two common metrics: the first moment of the diffusion tensor field (mean diffusivity, MD), and the fractional anisotropy (FA). We have shown in earlier work that ROI metrics and the mean of MD and FA histograms are not sufficiently sensitive for use in site characterization. Here we use the distance between whole brain histograms of FA and MD to investigate within- and between-site effects. We concluded that the variability of DTI metrics due to site, vendor, field strength, and echo time could influence the results in multi-center trials and that histogram distance is sensitive metrics for each of these variables. PMID:27350723

The UNC/UMN Baby Connectome Project (BCP): An overview of the study design and protocol development.

PubMed

Howell, Brittany R; Styner, Martin A; Gao, Wei; Yap, Pew-Thian; Wang, Li; Baluyot, Kristine; Yacoub, Essa; Chen, Geng; Potts, Taylor; Salzwedel, Andrew; Li, Gang; Gilmore, John H; Piven, Joseph; Smith, J Keith; Shen, Dinggang; Ugurbil, Kamil; Zhu, Hongtu; Lin, Weili; Elison, Jed T

2018-03-22

The human brain undergoes extensive and dynamic growth during the first years of life. The UNC/UMN Baby Connectome Project (BCP), one of the Lifespan Connectome Projects funded by NIH, is an ongoing study jointly conducted by investigators at the University of North Carolina at Chapel Hill and the University of Minnesota. The primary objective of the BCP is to characterize brain and behavioral development in typically developing infants across the first 5 years of life. The ultimate goals are to chart emerging patterns of structural and functional connectivity during this period, map brain-behavior associations, and establish a foundation from which to further explore trajectories of health and disease. To accomplish these goals, we are combining state of the art MRI acquisition and analysis techniques, including high-resolution structural MRI (T1-and T2-weighted images), diffusion imaging (dMRI), and resting state functional connectivity MRI (rfMRI). While the overall design of the BCP largely is built on the protocol developed by the Lifespan Human Connectome Project (HCP), given the unique age range of the BCP cohort, additional optimization of imaging parameters and consideration of an age appropriate battery of behavioral assessments were needed. Here we provide the overall study protocol, including approaches for subject recruitment, strategies for imaging typically developing children 0-5 years of age without sedation, imaging protocol and optimization, a description of the battery of behavioral assessments, and QA/QC procedures. Combining HCP inspired neuroimaging data with well-established behavioral assessments during this time period will yield an invaluable resource for the scientific community. Copyright © 2018 Elsevier Inc. All rights reserved.

Evaluation of PET and MR datasets in integrated 18F-FDG PET/MRI: A comparison of different MR sequences for whole-body restaging of breast cancer patients.

PubMed

Grueneisen, Johannes; Sawicki, Lino Morris; Wetter, Axel; Kirchner, Julian; Kinner, Sonja; Aktas, Bahriye; Forsting, Michael; Ruhlmann, Verena; Umutlu, Lale

2017-04-01

To investigate the diagnostic value of different MR sequences and 18F-FDG PET data for whole-body restaging of breast cancer patients utilizing PET/MRI. A total of 36 patients with suspected tumor recurrence of breast cancer based on clinical follow-up or abnormal findings in follow-up examinations (e.g. CT, MRI) were prospectively enrolled in this study. All patients underwent a PET/CT and subsequently an additional PET/MR scan. Two readers were instructed to identify the occurrence of a tumor relapse in subsequent MR and PET/MR readings, utilizing different MR sequence constellations for each session. The diagnostic confidence for the determination of a malignant or benign lesion was qualitatively rated (3-point ordinal scale) for each lesion in the different reading sessions and the lesion conspicuity (4-point ordinal scale) for the three different MR sequences was additionally evaluated. Tumor recurrence was present in 25/36 (69%) patients. All three PET/MRI readings showed a significantly higher accuracy as well as higher confidence levels for the detection of recurrent breast cancer lesions when compared to MRI alone (p<0.05). Furthermore, all three PET/MR sequence constellations showed comparable diagnostic accuracy for the identification of a breast cancer recurrence (p>0.05), yet the highest confidence levels were obtained, when all three MR sequences were used for image interpretation. Moreover, contrast-enhanced T1-weighted VIBE imaging showed significantly higher values for the delineation of malignant and benign lesions when compared to T2w HASTE and diffusion-weighted imaging. Integrated PET/MRI provides superior restaging of breast cancer patients over MRI alone. Facing the need for appropriate and efficient whole-body PET/MR protocols, our results show the feasibility of fast and morphologically adequate PET/MR protocols. However, considering an equivalent accuracy for the detection of breast cancer recurrences in the three PET/MR readings, the application of contrast-agent and the inclusion of DWI in the study protocol seems to be debatable. Copyright © 2017 Elsevier B.V. All rights reserved.

Creatine, Glutamine plus Glutamate, and Macromolecules Are Decreased in the Central White Matter of Premature Neonates around Term

PubMed Central

Le Fur, Yann; Viout, Patrick; Ratiney, Hélène; Confort-Gouny, Sylviane; Cozzone, Patrick J.; Girard, Nadine

2016-01-01

Preterm birth represents a high risk of neurodevelopmental disabilities when associated with white-matter damage. Recent studies have reported cognitive deficits in children born preterm without brain injury on MRI at term-equivalent age. Understanding the microstructural and metabolic underpinnings of these deficits is essential for their early detection. Here, we used diffusion-weighted imaging and single-voxel 1H magnetic resonance spectroscopy (MRS) to compare brain maturation at term-equivalent age in premature neonates with no evidence of white matter injury on conventional MRI except diffuse excessive high-signal intensity, and normal term neonates. Thirty-two infants, 16 term neonates (mean post-conceptional age at scan: 39.8±1 weeks) and 16 premature neonates (mean gestational age at birth: 29.1±2 weeks, mean post-conceptional age at scan: 39.2±1 weeks) were investigated. The MRI/MRS protocol performed at 1.5T involved diffusion-weighted MRI and localized 1H-MRS with the Point RESolved Spectroscopy (PRESS) sequence. Preterm neonates showed significantly higher ADC values in the temporal white matter (P<0.05), the occipital white matter (P<0.005) and the thalamus (P<0.05). The proton spectrum of the centrum semiovale was characterized by significantly lower taurine/H2O and macromolecules/H2O ratios (P<0.05) at a TE of 30 ms, and reduced (creatine+phosphocreatine)/H2O and (glutamine+glutamate)/H2O ratios (P<0.05) at a TE of 135 ms in the preterm neonates than in full-term neonates. Our findings indicate that premature neonates with normal conventional MRI present a delay in brain maturation affecting the white matter and the thalamus. Their brain metabolic profile is characterized by lower levels of creatine, glutamine plus glutamate, and macromolecules in the centrum semiovale, a finding suggesting altered energy metabolism and protein synthesis. PMID:27547969

Clinicoradiological Correlation of Infarct Patterns on Diffusion-weighted Magnetic Resonance Imaging in Stroke.

PubMed

Hussain, Zainab; Hilal, Kiran; Ahmad, Muhammad; Sajjad, Zafar; Sayani, Raza

2018-03-02

Diffusion-weighted magnetic resonance imaging (DW-MRI) represents a major advance in the early diagnosis of acute ischemic stroke. It can detect edema due to ischemia in the brain tissue. It not only establishes the presence and location of ischemic brain injury but also a relatively new concept is the determination of infarct patterns seen on diffusion imaging and its clinical correlation. Objective To determine the frequency of various infarct patterns and their relationship with functional outcome of the patient. Materials and methods A total of 108 patients with acute stroke were enrolled by purposive sampling. Magnetic resonance imaging (MRI) was obtained with departmental protocol and diffusion-weighted sequences. The clinical data was collected from medical records and functional outcome was assessed at the time of admission using Barthel Index (BI) which was dichotomized into poor and favorable outcomes. The radiological data was collected and three infarct patterns (cortical, subcortical, and territorial infarcts) were recorded from diffusion-weighted images. Association of other risk factors such as age, gender, diabetes, hypertension (HTN), hyperlipidemia, and smoking were also evaluated. Results Amongst the three infarct patterns, subcortical infarcts were noted with the highest proportion of 62% (67/108). The highest proportion of territorial infarcts (78.6%) was significantly associated with a poor outcome in comparison to cortical and subcortical infarcts. Cortical infarcts (61.5%) were significantly associated with good outcomes followed by subcortical and then territorial infarcts (p-value < 0.002). Amongst the risk factors, HTN was found to be highly prevalent followed by diabetes mellitus (DM). Conclusion Subcortical infarct pattern was the most common, followed by territorial and cortical infarct. The highest proportion of infarct pattern with good outcomes was seen with cortical infarcts followed by subcortical and then territorial infarct pattern. HTN and coronary artery disease (CAD) were the effect modifiers showing significant association with poor outcomes.

Diffusion-weighted MRI derived apparent diffusion coefficient identifies prognostically distinct subgroups of pediatric diffuse intrinsic pontine glioma.

PubMed

Lober, Robert M; Cho, Yoon-Jae; Tang, Yujie; Barnes, Patrick D; Edwards, Michael S; Vogel, Hannes; Fisher, Paul G; Monje, Michelle; Yeom, Kristen W

2014-03-01

While pediatric diffuse intrinsic pontine gliomas (DIPG) remain fatal, recent data have shown subgroups with distinct molecular biology and clinical behavior. We hypothesized that diffusion-weighted MRI can be used as a prognostic marker to stratify DIPG subsets with distinct clinical behavior. Apparent diffusion coefficient (ADC) values derived from diffusion-weighted MRI were computed in 20 consecutive children with treatment-naïve DIPG tumors. The median ADC for the cohort was used to stratify the tumors into low and high ADC groups. Survival, gender, therapy, and potential steroid effects were compared between the ADC groups. Median age at diagnosis was 6.6 (range 2.3-13.2) years, with median follow-up seven (range 1-36) months. There were 14 boys and six girls. Seventeen patients received radiotherapy, five received chemotherapy, and six underwent cerebrospinal fluid diversion. The median ADC of 1,295 × 10(-6) mm(2)/s for the cohort partitioned tumors into low or high diffusion groups, which had distinct median survivals of 3 and 13 months, respectively (log-rank p < 0.001). Low ADC tumors were found only in boys, whereas high ADC tumors were found in both boys and girls. Available tissue specimens in three low ADC tumors demonstrated high-grade histology, whereas one high ADC tumor demonstrated low-grade histology with a histone H3.1 K27M mutation and high-grade metastatic lesion at autopsy. ADC derived from diffusion-weighted MRI may identify prognostically distinct subgroups of pediatric DIPG.

Pretreatment Prediction of Brain Tumors' Response to Radiation Therapy Using High b-Value Diffusion-Weighted MRI1

PubMed Central

Mardor, Yael; Roth, Yiftach; Ocherashvilli, Aharon; Spiegelmann, Roberto; Tichler, Thomas; Daniels, Dianne; Maier, Stephan E; Nissim, Ouzi; Ram, Zvi; Baram, Jacob; Orenstein, Arie; Pfeffer, Raphael

2004-01-01

Abstract Diffusion-weighted magnetic resonance imaging (DWMRI) is sensitive to tissues' biophysical characteristics, including apparent diffusion coefficients (ADCs) and volume fractions of water in different populations. In this work, we evaluate the clinical efficacy of DWMRI and high diffusion-weighted magnetic resonance imaging (HDWMRI), acquired up to b = 4000 sec/mm2 to amplify sensitivity to water diffusion properties, in pretreatment prediction of brain tumors' response to radiotherapy. Twelve patients with 20 brain lesions were studied. Six ring-enhancing lesions were excluded due to their distinct diffusion characteristics. Conventional and DWMRI were acquired on a 0.5-T MRI. Response to therapy was determined from relative changes in tumor volumes calculated from contrast-enhanced T1-weighted MRI, acquired before and a mean of 46 days after beginning therapy. ADCs and a diffusion index, RD, reflecting tissue viability based on water diffusion were calculated from DWMRIs. Pretreatment values of ADC and RD were found to correlate significantly with later tumor response/nonresponse (r = 0.76, P < .002 and r = 0.77, P < .001). This correlation implies that tumors with low pretreatment diffusion values, indicating high viability, will respond better to radiotherapy than tumors with high diffusion values, indicating necrosis. These results demonstrate the feasibility of using DWMRI for pretreatment prediction of response to therapy in patients with brain tumors undergoing radiotherapy. PMID:15140402

Pretreatment prediction of brain tumors' response to radiation therapy using high b-value diffusion-weighted MRI.

PubMed

Mardor, Yael; Roth, Yiftach; Ochershvilli, Aharon; Spiegelmann, Roberto; Tichler, Thomas; Daniels, Dianne; Maier, Stephan E; Nissim, Ouzi; Ram, Zvi; Baram, Jacob; Orenstein, Arie; Pfeffer, Raphael

2004-01-01

Diffusion-weighted magnetic resonance imaging (DWMRI) is sensitive to tissues' biophysical characteristics, including apparent diffusion coefficients (ADCs) and volume fractions of water in different populations. In this work, we evaluate the clinical efficacy of DWMRI and high diffusion-weighted magnetic resonance imaging (HDWMRI), acquired up to b = 4000 sec/mm(2) to amplify sensitivity to water diffusion properties, in pretreatment prediction of brain tumors' response to radiotherapy. Twelve patients with 20 brain lesions were studied. Six ring-enhancing lesions were excluded due to their distinct diffusion characteristics. Conventional and DWMRI were acquired on a 0.5-T MRI. Response to therapy was determined from relative changes in tumor volumes calculated from contrast-enhanced T1-weighted MRI, acquired before and a mean of 46 days after beginning therapy. ADCs and a diffusion index, R(D), reflecting tissue viability based on water diffusion were calculated from DWMRIs. Pretreatment values of ADC and R(D) were found to correlate significantly with later tumor response/nonresponse (r = 0.76, P <.002 and r = 0.77, P <.001). This correlation implies that tumors with low pretreatment diffusion values, indicating high viability, will respond better to radiotherapy than tumors with high diffusion values, indicating necrosis. These results demonstrate the feasibility of using DWMRI for pretreatment prediction of response to therapy in patients with brain tumors undergoing radiotherapy.

Application of Paramagnetically Tagged Molecules for Magnetic Resonance Imaging of Biofilm Mass Transport Processes▿

PubMed Central

Ramanan, B.; Holmes, W. M.; Sloan, W. T.; Phoenix, V. R.

2010-01-01

Molecules become readily visible by magnetic resonance imaging (MRI) when labeled with a paramagnetic tag. Consequently, MRI can be used to image their transport through porous media. In this study, we demonstrated that this method could be applied to image mass transport processes in biofilms. The transport of a complex of gadolinium and diethylenetriamine pentaacetic acid (Gd-DTPA), a commercially available paramagnetic molecule, was imaged both in agar (as a homogeneous test system) and in a phototrophic biofilm. The images collected were T1 weighted, where T1 is an MRI property of the biofilm and is dependent on Gd-DTPA concentration. A calibration protocol was applied to convert T1 parameter maps into concentration maps, thus revealing the spatially resolved concentrations of this tracer at different time intervals. Comparing the data obtained from the agar experiment with data from a one-dimensional diffusion model revealed that transport of Gd-DTPA in agar was purely via diffusion, with a diffusion coefficient of 7.2 × 10−10 m2 s−1. In contrast, comparison of data from the phototrophic biofilm experiment with data from a two-dimensional diffusion model revealed that transport of Gd-DTPA inside the biofilm was by both diffusion and advection, equivalent to a diffusion coefficient of 1.04 × 10−9 m2 s−1. This technology can be used to further explore mass transport processes in biofilms, either by using the wide range of commercially available paramagnetically tagged molecules and nanoparticles or by using bespoke tagged molecules. PMID:20435773

Weighted linear least squares estimation of diffusion MRI parameters: strengths, limitations, and pitfalls.

PubMed

Veraart, Jelle; Sijbers, Jan; Sunaert, Stefan; Leemans, Alexander; Jeurissen, Ben

2013-11-01

Linear least squares estimators are widely used in diffusion MRI for the estimation of diffusion parameters. Although adding proper weights is necessary to increase the precision of these linear estimators, there is no consensus on how to practically define them. In this study, the impact of the commonly used weighting strategies on the accuracy and precision of linear diffusion parameter estimators is evaluated and compared with the nonlinear least squares estimation approach. Simulation and real data experiments were done to study the performance of the weighted linear least squares estimators with weights defined by (a) the squares of the respective noisy diffusion-weighted signals; and (b) the squares of the predicted signals, which are reconstructed from a previous estimate of the diffusion model parameters. The negative effect of weighting strategy (a) on the accuracy of the estimator was surprisingly high. Multi-step weighting strategies yield better performance and, in some cases, even outperformed the nonlinear least squares estimator. If proper weighting strategies are applied, the weighted linear least squares approach shows high performance characteristics in terms of accuracy/precision and may even be preferred over nonlinear estimation methods. Copyright © 2013 Elsevier Inc. All rights reserved.

A spin echo sequence with a single-sided bipolar diffusion gradient pulse to obtain snapshot diffusion weighted images in moving media

NASA Astrophysics Data System (ADS)

Freidlin, R. Z.; Kakareka, J. W.; Pohida, T. J.; Komlosh, M. E.; Basser, P. J.

2012-08-01

In vivo MRI data can be corrupted by motion. Motion artifacts are particularly troublesome in Diffusion Weighted MRI (DWI), since the MR signal attenuation due to Brownian motion can be much less than the signal loss due to dephasing from other types of complex tissue motion, which can significantly degrade the estimation of self-diffusion coefficients, diffusion tensors, etc. This paper describes a snapshot DWI sequence, which utilizes a novel single-sided bipolar diffusion sensitizing gradient pulse within a spin echo sequence. The proposed method shortens the diffusion time by applying a single refocused bipolar diffusion gradient on one side of a refocusing RF pulse, instead of a set of diffusion sensitizing gradients, separated by a refocusing RF pulse, while reducing the impact of magnetic field inhomogeneity by using a spin echo sequence. A novel MRI phantom that can exhibit a range of complex motions was designed to demonstrate the robustness of the proposed DWI sequence.

Single-shot turbo spin echo acquisition for in vivo cardiac diffusion MRI.

PubMed

Edalati, Masoud; Lee, Gregory R; Hui Wang; Taylor, Michael D; Li, Yu Y

2016-08-01

Diffusion MRI offers the ability to noninvasively characterize the microstructure of myocardium tissue and detect disease related pathology in cardiovascular examination. This study investigates the feasibility of in vivo cardiac diffusion MRI under free-breathing condition. A high-speed imaging technique, correlation imaging, is used to enable single-shot turbo spin echo for free-breathing cardiac data acquisition. The obtained in vivo cardiac diffusion-weighted images illustrate robust image quality and minor geometry distortions. The resultant diffusion scalar maps show reliable quantitative values consistent with those previously published in the literature. It is demonstrated that this technique has the potential for in vivo free-breathing cardiac diffusion MRI.

The Role of Diffusion-Weighted Magnetic Resonance Imaging in the Differentiation of Head and Neck Masses.

PubMed

Kanmaz, Lutfi; Karavas, Erdal

2018-05-29

The purpose of this study was to evaluate the value of diffusion-weighted MRI (DW-MRI) in differentiating benign and malignant head and neck masses by comparing their apparent diffusion coefficient (ADC) values. The study included 32 patients with a neck mass >1 cm in diameter who were examined with echo planar DW-MRI. Two different diffusion gradients (b values of b = 0 and b = 1000 s/mm²) were applied. DWI and ADC maps of 32 neck masses in 32 patients were obtained. Mean ADC values of benign and malignant neck lesions were measured and compared statistically. A total of 15 (46.9%) malignant masses and 17 (53.1%) benign masses were determined. Of all the neck masses, the ADC value of cystic masses was the highest and that of lymphomas was the lowest. The mean ADC values of benign and malignant neck masses were 1.57 × 10 -3 mm²/s and 0.90 × 10 -3 mm²/s, respectively. The difference between mean ADC values of benign and malignant neck masses was significant ( p < 0.01). Diffusion-weighted MRI with ADC measurements can be useful in the differential diagnosis of neck masses.

Machine-learning in grading of gliomas based on multi-parametric magnetic resonance imaging at 3T.

PubMed

Citak-Er, Fusun; Firat, Zeynep; Kovanlikaya, Ilhami; Ture, Ugur; Ozturk-Isik, Esin

2018-06-15

The objective of this study was to assess the contribution of multi-parametric (mp) magnetic resonance imaging (MRI) quantitative features in the machine learning-based grading of gliomas with a multi-region-of-interests approach. Forty-three patients who were newly diagnosed as having a glioma were included in this study. The patients were scanned prior to any therapy using a standard brain tumor magnetic resonance (MR) imaging protocol that included T1 and T2-weighted, diffusion-weighted, diffusion tensor, MR perfusion and MR spectroscopic imaging. Three different regions-of-interest were drawn for each subject to encompass tumor, immediate tumor periphery, and distant peritumoral edema/normal. The normalized mp-MRI features were used to build machine-learning models for differentiating low-grade gliomas (WHO grades I and II) from high grades (WHO grades III and IV). In order to assess the contribution of regional mp-MRI quantitative features to the classification models, a support vector machine-based recursive feature elimination method was applied prior to classification. A machine-learning model based on support vector machine algorithm with linear kernel achieved an accuracy of 93.0%, a specificity of 86.7%, and a sensitivity of 96.4% for the grading of gliomas using ten-fold cross validation based on the proposed subset of the mp-MRI features. In this study, machine-learning based on multiregional and multi-parametric MRI data has proven to be an important tool in grading glial tumors accurately even in this limited patient population. Future studies are needed to investigate the use of machine learning algorithms for brain tumor classification in a larger patient cohort. Copyright © 2018. Published by Elsevier Ltd.

Comparative sensitivities of functional MRI sequences in detection of local recurrence of prostate carcinoma after radical prostatectomy or external-beam radiotherapy.

PubMed

Roy, Catherine; Foudi, Fatah; Charton, Jeanne; Jung, Michel; Lang, Hervé; Saussine, Christian; Jacqmin, Didier

2013-04-01

The aim of this retrospective study was to determine the respective accuracies of three types of functional MRI sequences-diffusion-weighted imaging (DWI), dynamic contrast-enhanced (DCE) MRI, and 3D (1)H-MR spectroscopy (MRS)-in the depiction of local prostate cancer recurrence after two different initial therapy options. From a cohort of 83 patients with suspicion of local recurrence based on prostate-specific antigen (PSA) kinetics who were imaged on a 3-T MRI unit using an identical protocol including the three functional sequences with an endorectal coil, we selected 60 patients (group A, 28 patients who underwent radical prostatectomy; group B, 32 patients who underwent external-beam radiation) who had local recurrence ascertained on the basis of a transrectal ultrasound-guided biopsy results and a reduction in PSA level after salvage therapy. All patients presented with a local relapse. Sensitivity with T2-weighted MRI and 3D (1)H-MRS sequences was 57% and 53%, respectively, for group A and 71% and 78%, respectively, for group B. DCE-MRI alone showed a sensitivity of 100% and 96%, respectively, for groups A and B. DWI alone had a higher sensitivity for group B (96%) than for group A (71%). The combination of T2-weighted imaging plus DWI plus DCE-MRI provided a sensitivity as high as 100% in group B. The performance of functional imaging sequences for detecting recurrence is different after radical prostatectomy and external-beam radiotherapy. DCE-MRI is a valid and efficient tool to detect prostate cancer recurrence in radical prostatectomy as well as in external-beam radiotherapy. The combination of DCE-MRI and DWI is highly efficient after radiation therapy. Three-dimensional (1)H-MRS needs to be improved. Even though it is not accurate enough, T2-weighted imaging remains essential for the morphologic analysis of the area.

Role of diffusion-weighted MRI in differentiation of hepatic abscesses from non-infected fluid collections.

PubMed

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 < 0.01). Mean ADC values were significantly lower with abscesses versus non-infected fluid collections (0.83 ± 0.24 versus 2.25 ± 0.61 × 10(-3) mm(2)/s; p < 0.001). With ROC analysis there was good discrimination of abscess from non-infected fluid 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.

A Comparison of Ultrasonography, Computerised Tomography, and Conventional MRI Findings for Splenic Nodules Associated with Type 1 Gaucher’s Disease with Diffusion-Weighted MRI Findings

PubMed Central

Albayrak, Eda; Sonmezgoz, Fitnet; Ozmen, Zafer; Aktas, Fatma; Altunkas, Aysegul

2017-01-01

A 26-year-old female patient with Type 1 Gaucher’s disease (GD) was admitted to our clinic with complaints of stomachache and signs of anemia. The patient underwent ultrasonography (US), computerised tomography (CT), and magnetic resonance imaging (MRI) scan. Imaging studies revealed massive hepatosplenomegaly, choledocolithiasis, and six nodules in the spleen with a mean size of 14 mm. The nodules appeared hyperechoic, hypoechoic, and of mixed echogenicity on the US and hypodense on the CT. While the nodules were observed to be iso-hypointense in T1-weighted (T1WI) images, they appeared to be hyperintense in the T2-weighted (T2WI) images. There were no diffusion restrictions in these nodules that appeared on the diffusion-weighted magnetic resonance imaging (DWI). A nodule located at the lower pole was observed to be hypointense in the T2WI images. The nodule located at the lower pole, which appeared hypointense in T2WI series, had restricted diffusion upon DWI. In this study, we aimed to present the properties of splenic GD nodules using US, CT, and conventional MRI, together with DWI. This case report is the first to apply US, CT, and conventional MRI, together with DWI, to the splenic nodules associated with Gaucher’s disease. PMID:29386979

SU-D-207A-03: Potential Role of BOLD MRI in Discrimination of Aggressive Tumor Habitat in Prostate Cancer

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

Ford, J; Lopez, C; Tschudi, Y

Purpose: To determine whether blood oxygenation level dependent (BOLD) MRI signal measured in prostate cancer patients, in addition to quantitative diffusion and perfusion parameters from multiparametric (mp)MRI exams, can help discriminate aggressive and/or radioresistant lesions. Methods: Several ongoing clinical trials in our institution require mpMRI exam to determine eligibility (presence of identifiable tumor lesion on mpMRI) and prostate volumes for dose escalation. Upon consent, patients undergo fiducial markers placement and a T2*-weighted imaging at the time of CT sim to facilitate the fusion. In a retrospective analysis eleven clinical trial patients were identified who had undergone mpMRI on GE 3Tmore » magnet, followed by T2*-weighted imaging (time-period mean±SD = 48±20 days) using a consistent protocol (gradient echo, TR/TE=30/11.8ms, flip angle=12, matrix=256×256×75, voxel size=1.25×1.25×2.5mm). ROIs for prostate tumor lesions were automatically determined using ADC threshold ≤1200 µm2/s. Although the MR protocol was not intended for BOLD analysis, we utilized the T2*-weighted signal normalized to that in nearby muscle; likewise, T2-weighted lesion signal was normalized to muscle, following rigid registration of the T2 to T2* images. The ratio of these normalized signals, T2*/T2, is a measure of BOLD effect in the prostate tumors. Perfusion parameters (Ktrans, ve, kep) were also calculated. Results: T2*/T2 (mean±SE) was found to be substantially lower for Gleason score (GS) 8&9 (0.82±0.04) compared to GS 7 (1.08±0.07). A k-means cluster analysis of T2*/T2 versus kep = Ktrans/ve revealed two distinct clusters, one with higher T2*/T2 and lower kep, containing only GS 7 lesions, and another with lower T2*/T2 and higher kep, associated with tumor aggressiveness. This latter cluster contained all GS 8&9 lesions, as well as some GS 7. Conclusion: BOLD MRI, in addition to ADC and kep, may play a role (perhaps orthogonal to Gleason score) in identifying prostate lesions that would benefit from more aggressive radiotherapy.« less

Idiopathic granulomatous mastitis: magnetic resonance imaging findings with diffusion MRI.

PubMed

Aslan, Hulya; Pourbagher, Aysin; Colakoglu, Tamer

2016-07-01

Idiopathic granulomatous mastitis (IGM) is a rare benign breast disease with unknown etiology which can mimic breast carcinoma, both clinically and radiologically. Magnetic resonance imaging (MRI) findings of IGM have been previously described; however there is no study evaluating diffusion-weighted MRI findings of IGM. To analyze conventional, dynamic contrast-enhanced, and diffusion-weighted MRI signal characteristics of IGM by comparing it with the contralateral normal breast parenchyma. A total of 39 patients were included in the study. On dynamic contrast-enhanced MRI, the distribution and enhancement patterns of the lesions were evaluated. We also detected the frequencies of involving quadrants, retroareolar involvement, accompanying abscess, and skin edema. T2-weighted (T2W) and STIR signal intensities and both mean and minimum apparent diffusion coefficient (ADC) values were compared with the contralateral normal parenchyma. IGM showed significantly lower mean and minimum ADC values when compared with the normal parenchyma. Signal intensities on T2W and STIR sequences of the lesion were significantly higher than the normal parenchyma. On dynamic contrast-enhanced MRI, 7.7% of the patients had mass-like contrast enhancement, 92.3% of the patients had non-mass-like contrast enhancement. Abscess was positive in 33.3% of the patients. As a result, IGM showed commonly non-mass-like lesions with restricted diffusion. Although it is a benign pathology, it may show clustered ring-like enhancement like malignant lesions. © The Foundation Acta Radiologica 2015.

Basic concepts of MR imaging, diffusion MR imaging, and diffusion tensor imaging.

PubMed

de Figueiredo, Eduardo H M S G; Borgonovi, Arthur F N G; Doring, Thomas M

2011-02-01

MR image contrast is based on intrinsic tissue properties and specific pulse sequences and parameter adjustments. A growing number of MRI imaging applications are based on diffusion properties of water. To better understand MRI diffusion-weighted imaging, a brief overview of MR physics is presented in this article followed by physics of the evolving techniques of diffusion MR imaging and diffusion tensor imaging. Copyright © 2011. Published by Elsevier Inc.

Experimental considerations for fast kurtosis imaging.

PubMed

Hansen, Brian; Lund, Torben E; Sangill, Ryan; Stubbe, Ebbe; Finsterbusch, Jürgen; Jespersen, Sune Nørhøj

2016-11-01

The clinical use of kurtosis imaging is impeded by long acquisitions and postprocessing. Recently, estimation of mean kurtosis tensor W¯ and mean diffusivity ( D¯) was made possible from 13 distinct diffusion weighted MRI acquisitions (the 1-3-9 protocol) with simple postprocessing. Here, we analyze the effects of noise and nonideal diffusion encoding, and propose a new correction strategy. We also present a 1-9-9 protocol with increased robustness to experimental imperfections and minimal additional scan time. This refinement does not affect computation time and also provides a fast estimate of fractional anisotropy (FA). 1-3-9/1-9-9 data are acquired in rat and human brains, and estimates of D¯, FA, W¯ from human brains are compared with traditional estimates from an extensive diffusion kurtosis imaging data set. Simulations are used to evaluate the influence of noise and diffusion encodings deviating from the scheme, and the performance of the correction strategy. Optimal b-values are determined from simulations and data. Accuracy and precision in D¯ and W¯ are comparable to nonlinear least squares estimation, and is improved with the 1-9-9 protocol. The compensation strategy vastly improves parameter estimation in nonideal data. The framework offers a robust and compact method for estimating several diffusion metrics. The protocol is easily implemented. Magn Reson Med 76:1455-1468, 2016. © 2015 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. © 2015 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine.

Comparison of block and event-related experimental designs in diffusion-weighted functional MRI.

PubMed

Williams, Rebecca J; McMahon, Katie L; Hocking, Julia; Reutens, David C

2014-08-01

To compare diffusion-weighted functional magnetic resonance imaging (DfMRI), a novel alternative to the blood oxygenation level-dependent (BOLD) contrast, in a functional MRI experiment. Nine participants viewed contrast reversing (7.5 Hz) black-and-white checkerboard stimuli using block and event-related paradigms. DfMRI (b = 1800 mm/s(2)) and BOLD sequences were acquired. Four parameters describing the observed signal were assessed: percent signal change, spatial extent of the activation, the Euclidean distance between peak voxel locations, and the time-to-peak of the best fitting impulse response for different paradigms and sequences. The BOLD conditions showed a higher percent signal change relative to DfMRI; however, event-related DfMRI showed the strongest group activation (t = 21.23, P < 0.0005). Activation was more diffuse and spatially closer to the BOLD response for DfMRI when the block design was used. DfMRIevent showed the shortest TTP (4.4 ± 0.88 sec). The hemodynamic contribution to DfMRI may increase with the use of block designs. © 2013 Wiley Periodicals, Inc.

Single-shot ADC imaging for fMRI.

PubMed

Song, Allen W; Guo, Hua; Truong, Trong-Kha

2007-02-01

It has been suggested that apparent diffusion coefficient (ADC) contrast can be sensitive to cerebral blood flow (CBF) changes during brain activation. However, current ADC imaging techniques have an inherently low temporal resolution due to the requirement of multiple acquisitions with different b-factors, as well as potential confounds from cross talk between the deoxyhemoglobin-induced background gradients and the externally applied diffusion-weighting gradients. In this report a new method is proposed and implemented that addresses these two limitations. Specifically, a single-shot pulse sequence that sequentially acquires one gradient-echo (GRE) and two diffusion-weighted spin-echo (SE) images was developed. In addition, the diffusion-weighting gradient waveform was numerically optimized to null the cross terms with the deoxyhemoglobin-induced background gradients to fully isolate the effect of diffusion weighting from that of oxygenation-level changes. The experimental results show that this new single-shot method can acquire ADC maps with sufficient signal-to-noise ratio (SNR), and establish its practical utility in functional MRI (fMRI) to complement the blood oxygenation level-dependent (BOLD) technique and provide differential sensitivity for different vasculatures to better localize neural activity originating from the small vessels. Copyright (c) 2007 Wiley-Liss, Inc.

Combining diffusion-weighted MRI with Gd-EOB-DTPA-enhanced MRI improves the detection of colorectal liver metastases.

PubMed

Koh, D-M; Collins, D J; Wallace, T; Chau, I; Riddell, A M

2012-07-01

To compare the diagnostic accuracy of gadolinium-ethoxybenzyl-diethylenetriaminepentaacetic acid (Gd-EOB-DTPA)-enhanced MRI, diffusion-weighted MRI (DW-MRI) and a combination of both techniques for the detection of colorectal hepatic metastases. 72 patients with suspected colorectal liver metastases underwent Gd-EOB-DTPA MRI and DW-MRI. Images were retrospectively reviewed with unenhanced T(1) and T(2) weighted images as Gd-EOB-DTPA image set, DW-MRI image set and combined image set by two independent radiologists. Each lesion detected was scored for size, location and likelihood of metastasis, and compared with surgery and follow-up imaging. Diagnostic accuracy was compared using receiver operating characteristics and interobserver agreement by kappa statistics. 417 lesions (310 metastases, 107 benign) were found in 72 patients. For both readers, diagnostic accuracy using the combined image set was higher [area under the curve (Az)=0.96, 0.97] than Gd-EOB-DTPA image set (Az=0.86, 0.89) or DW-MRI image set (Az=0.93, 0.92). Using combined image set improved identification of liver metastases compared with Gd-EOB-DTPA image set (p<0.001) or DW-MRI image set (p<0.001). There was very good interobserver agreement for lesion classification (κ=0.81-0.88). Combining DW-MRI with Gd-EOB-DTPA-enhanced T(1) weighted MRI significantly improved the detection of colorectal liver metastases.

Super-resolution reconstruction of diffusion parameters from diffusion-weighted images with different slice orientations.

PubMed

Van Steenkiste, Gwendolyn; Jeurissen, Ben; Veraart, Jelle; den Dekker, Arnold J; Parizel, Paul M; Poot, Dirk H J; Sijbers, Jan

2016-01-01

Diffusion MRI is hampered by long acquisition times, low spatial resolution, and a low signal-to-noise ratio. Recently, methods have been proposed to improve the trade-off between spatial resolution, signal-to-noise ratio, and acquisition time of diffusion-weighted images via super-resolution reconstruction (SRR) techniques. However, during the reconstruction, these SRR methods neglect the q-space relation between the different diffusion-weighted images. An SRR method that includes a diffusion model and directly reconstructs high resolution diffusion parameters from a set of low resolution diffusion-weighted images was proposed. Our method allows an arbitrary combination of diffusion gradient directions and slice orientations for the low resolution diffusion-weighted images, optimally samples the q- and k-space, and performs motion correction with b-matrix rotation. Experiments with synthetic data and in vivo human brain data show an increase of spatial resolution of the diffusion parameters, while preserving a high signal-to-noise ratio and low scan time. Moreover, the proposed SRR method outperforms the previous methods in terms of the root-mean-square error. The proposed SRR method substantially increases the spatial resolution of MRI that can be obtained in a clinically feasible scan time. © 2015 Wiley Periodicals, Inc.

Diffusion-weighted magnetic resonance imaging and apparent diffusion coefficient mapping for diagnosing infectious spondylodiscitis: a preliminary study.

PubMed

Chen, Tai-Yuan; Wu, Te-Chang; Tsui, Yu-Kun; Chen, Hou-Hsun; Lin, Chien-Jen; Lee, Huey-Jen; Wu, Tai-Ching

2015-01-01

Though diffusion-weighted (DW) magnetic resonance imaging (MRI) is useful for diagnosing many pathologies, its use in infectious spondylodiscitis is unclear. We aimed to evaluate the use of DW MRI and apparent diffusion coefficient (ADC) mapping for the diagnosis of infectious spondylodiscitis. In this retrospective study, 17 patients with confirmed infectious spondylodiscitis were matched by age and level of infected disc with 17 patients with degenerative disc disease (DDD) and 17 healthy controls. All patients received conventional MRI and diffusion-weighted imaging (DWI) in the same imaging session. ADC values of the 3 groups of patients were compared. The mean age of each group was 67.4 ± 11.6 years. The mean ADCs of the normal control, DDD, and infectious spondylodiscitis groups were 1.76 ± 0.19 × 10(-3) , 1.12 ± 0.22 × 10(-3) , and 1.27 ± 0.38 × 10(-3) mm2 /second, respectively. The ADCs of the DDD and infectious spondylodiscitis groups were both significantly lower than that of the normal control group (both, P < 0.001). These data suggest that DWI/ADC MRI may be useful in the early diagnosis of infectious spondylodiscitis. © 2014 The Authors. Journal of Neuroimaging published by Wiley Periodicals, Inc. on behalf of American Society of Neuroimaging.

Significance of diffusion weighted imaging (DWI) as an improving factor in contrast enhanced magnetic resonance imaging (MRI) enterography in evaluation of patients with Crohn's disease.

PubMed

Imširović, Bilal; Zerem, Enver; Efendić, Alma; Mekić Abazović, Alma; Zerem, Omar; Djedović, Muhamed

2018-08-01

Aim To determine capabilities and potential of contrast enhanced magnetic resonance imaging (MRI) enterography in order to establish the diagnosis and to evaluate severity and activity of intestinal inflammation. Methods Fifty-five patients with suspicion for presence of Crohn's disease were evaluated. All patients underwent contrast enhanced MRI enterography and diffusion weighted imaging (DWI), and subsequently endoscopic examination or surgical treatment. Four parameters were analysed: thickening of the bowel wall, and presence of abscess, fistula and lymphadenopathy. Results Comparing results of DWI and contrast enhanced MRI enterography a significant difference between results given through diffusion and histopathological test was found, e.g. a significant difference between results obtained through diffusion and MRI enterography was found. MRI enterography sensitiveness for bowel wall thickening was 97.7% and specificity 70%, whilst DWI sensitivity for bowel wall thickening was 84% and specificity 100%. The diagnostics of abscess and fistula showed no significant difference between DWI and MRI, while in lymphadenopathy significant difference between contrast enhanced MRI enterography and DWI was found. Conclusion Contrast enhanced MRI enterography in combination with DWI allows for excellent evaluation of disease activity, but also problems or complications following it. The examination can be repeated, controlled, and it can contribute to monitoring of patients with this disease. Copyright© by the Medical Assotiation of Zenica-Doboj Canton.

Methods to Differentiate Radiation Necrosis and Recurrent Disease in Gliomas

NASA Astrophysics Data System (ADS)

Ewell, Lars

2007-03-01

Given the difficulty in differentiating Radiation Induced Necrosis (RIN) and recurrent disease in glioma patients using conventional techniques (CT scans, MRI scans), researchers have looked for different imaging modalities. Among these different modalities are Diffusion Weighted Magnetic Resonance Imaging (DWMRI) and Magnetic Resonance Spectroscopy (MRS). In DWMRI, an Apparent Diffusion Coefficient (ADC) is calculated for a Region Of Interest (ROI), and then monitored over time (longitudinally). In the brain, different anatomical features can complicate the interpretation of ADCs. In particular, the density and spatial variation of the cerebral spinal fluid filled fissures known as sulci can influence how a change in an ADC is explained. We have used the covariance of pixel intensity in T1 weighted MRI scans to study how intra-patient and inter-patient sulci density varies, and will present these results. MRS uses the shift in the MR signal due to the local chemical environment to determine the concentration of brain metabolites like choline and creatin. The ratio of metabolites such as these has been shown to have the power to discriminate between RIN and recurrent disease in glioma patients. At our institution, we have initiated a protocol whereby we will use DWMRI and MRS to study how best to utilize these complimentary forms of imaging.

b matrix errors in echo planar diffusion tensor imaging

PubMed Central

Boujraf, Saïd; Luypaert, Robert; Osteaux, Michel

2001-01-01

Diffusion‐weighted magnetic resonance imaging (DW‐MRI) is a recognized tool for early detection of infarction of the human brain. DW‐MRI uses the signal loss associated with the random thermal motion of water molecules in the presence of magnetic field gradients to derive parameters that reflect the translational mobility of the water molecules in tissues. If diffusion‐weighted images with different values of b matrix are acquired during one individual investigation, it is possible to calculate apparent diffusion coefficient maps that are the elements of the diffusion tensor. The diffusion tensor elements represent the apparent diffusion coefficient of protons of water molecules in each pixel in the corresponding sample. The relation between signal intensity in the diffusion‐weighted images, diffusion tensor, and b matrix is derived from the Bloch equations. Our goal is to establish the magnitude of the error made in the calculation of the elements of the diffusion tensor when the imaging gradients are ignored. PACS number(s): 87.57. –s, 87.61.–c PMID:11602015

TIA triage in emergency department using acute MRI (TIA-TEAM): a feasibility and safety study.

PubMed

Vora, Nirali; Tung, Christie E; Mlynash, Michael; Garcia, Madelleine; Kemp, Stephanie; Kleinman, Jonathan; Zaharchuk, Greg; Albers, Gregory; Olivot, Jean-Marc

2015-04-01

Positive diffusion weighted imaging (DWI) on MRI is associated with increased recurrent stroke risk in TIA patients. Acute MRI aids in TIA risk stratification and diagnosis. To evaluate the feasibility and safety of TIA triage directly from the emergency department (ED) with acute MRI and neurological consultation. Consecutive ED TIA patients assessed by a neurologist underwent acute MRI/MRA of head/neck per protocol and were hospitalized if positive DWI, symptomatic vessel stenosis, or per clinical judgment. Stroke neurologist adjudicated the final TIA diagnosis as definite, possible, or not a cerebrovascular event. Stroke recurrence rates were calculated at 7, 90, 365 days and compared with predicted stroke rates derived from historical DWI and ABCD(2) score data. One hundred twenty-nine enrolled patients had a mean age of 69 years (± 17) and median ABCD(2) score of 3 (interquartile range [IQR] 3-4). During triage, 112 (87%) patients underwent acute MRI after a median of 16 h (IQR 10-23) from symptom onset. No patients experienced a recurrent event before imaging. Twenty-four (21%) had positive DWI and 8 (7%) had symptomatic vessel stenosis. Of the total cohort, 83 (64%) were discharged and 46 (36%) were hospitalized. By one-year follow-up, one patient in each group had experienced a stroke. Of 92 patients with MRI and index cerebrovascular event, recurrent stroke rates were 1.1% at 7 and 90 days. These were similar to predicted recurrence rates. TIA triage in the ED using a protocol with neurological consultation and acute MRI is feasible and safe. The majority of patients were discharged without hospitalization and rates of recurrent stroke were not higher than predicted. © 2014 World Stroke Organization.

Tensor Based Representation and Analysis of Diffusion-Weighted Magnetic Resonance Images

ERIC Educational Resources Information Center

Barmpoutis, Angelos

2009-01-01

Cartesian tensor bases have been widely used to model spherical functions. In medical imaging, tensors of various orders can approximate the diffusivity function at each voxel of a diffusion-weighted MRI data set. This approximation produces tensor-valued datasets that contain information about the underlying local structure of the scanned tissue.…

Small-bowel MRI in children and young adults with Crohn disease: retrospective head-to-head comparison of contrast-enhanced and diffusion-weighted MRI.

PubMed

Neubauer, Henning; Pabst, Thomas; Dick, Anke; Machann, Wolfram; Evangelista, Laura; Wirth, Clemens; Köstler, Herbert; Hahn, Dietbert; Beer, Meinrad

2013-01-01

Small-bowel MRI based on contrast-enhanced T1-weighted sequences has been challenged by diffusion-weighted imaging (DWI) for detection of inflammatory bowel lesions and complications in patients with Crohn disease. To evaluate free-breathing DWI, as compared to contrast-enhanced MRI, in children, adolescents and young adults with Crohn disease. This retrospective study included 33 children and young adults with Crohn disease ages 17 ± 3 years (mean ± standard deviation) and 27 matched controls who underwent small-bowel MRI with contrast-enhanced T1-weighted sequences and DWI at 1.5 T. The detectability of Crohn manifestations was determined. Concurrent colonoscopy as reference was available in two-thirds of the children with Crohn disease. DWI and contrast-enhanced MRI correctly identified 32 and 31 patients, respectively. All 22 small-bowel lesions and all Crohn complications were detected. False-positive findings (two on DWI, one on contrast-enhanced MRI), compared to colonoscopy, were a result of large-bowel lumen collapse. Inflammatory wall thickening was comparable on DWI and contrast-enhanced MRI. DWI was superior to contrast-enhanced MRI for detection of lesions in 27% of the assessed bowel segments and equal to contrast-enhanced MRI in 71% of segments. DWI facilitates fast, accurate and comprehensive workup in Crohn disease without the need for intravenous administration of contrast medium. Contrast-enhanced MRI is superior in terms of spatial resolution and multiplanar acquisition.

Training-induced improvements in postural control are accompanied by alterations in cerebellar white matter in brain injured patients.

PubMed

Drijkoningen, David; Caeyenberghs, Karen; Leunissen, Inge; Vander Linden, Catharine; Leemans, Alexander; Sunaert, Stefan; Duysens, Jacques; Swinnen, Stephan P

2015-01-01

We investigated whether balance control in young TBI patients can be promoted by an 8-week balance training program and whether this is associated with neuroplastic alterations in brain structure. The cerebellum and cerebellar peduncles were selected as regions of interest because of their importance in postural control as well as their vulnerability to brain injury. Young patients with moderate to severe TBI and typically developing (TD) subjects participated in balance training using PC-based portable balancers with storage of training data and real-time visual feedback. An additional control group of TD subjects did not attend balance training. Mean diffusivity and fractional anisotropy were determined with diffusion MRI scans and were acquired before, during (4 weeks) and at completion of training (8 weeks) together with balance assessments on the EquiTest® System (NeuroCom) which included the Sensory Organization Test, Rhythmic Weight Shift and Limits of Stability protocols. Following training, TBI patients showed significant improvements on all EquiTest protocols, as well as a significant increase in mean diffusivity in the inferior cerebellar peduncle. Moreover, in both training groups, diffusion metrics in the cerebellum and/or cerebellar peduncles at baseline were predictive of the amount of performance increase after training. Finally, amount of training-induced improvement on the Rhythmic Weight Shift test in TBI patients was positively correlated with amount of change in fractional anisotropy in the inferior cerebellar peduncle. This suggests that training-induced plastic changes in balance control are associated with alterations in the cerebellar white matter microstructure in TBI patients.

Training-induced improvements in postural control are accompanied by alterations in cerebellar white matter in brain injured patients

PubMed Central

Drijkoningen, David; Caeyenberghs, Karen; Leunissen, Inge; Vander Linden, Catharine; Leemans, Alexander; Sunaert, Stefan; Duysens, Jacques; Swinnen, Stephan P.

2014-01-01

We investigated whether balance control in young TBI patients can be promoted by an 8-week balance training program and whether this is associated with neuroplastic alterations in brain structure. The cerebellum and cerebellar peduncles were selected as regions of interest because of their importance in postural control as well as their vulnerability to brain injury. Young patients with moderate to severe TBI and typically developing (TD) subjects participated in balance training using PC-based portable balancers with storage of training data and real-time visual feedback. An additional control group of TD subjects did not attend balance training. Mean diffusivity and fractional anisotropy were determined with diffusion MRI scans and were acquired before, during (4 weeks) and at completion of training (8 weeks) together with balance assessments on the EquiTest® System (NeuroCom) which included the Sensory Organization Test, Rhythmic Weight Shift and Limits of Stability protocols. Following training, TBI patients showed significant improvements on all EquiTest protocols, as well as a significant increase in mean diffusivity in the inferior cerebellar peduncle. Moreover, in both training groups, diffusion metrics in the cerebellum and/or cerebellar peduncles at baseline were predictive of the amount of performance increase after training. Finally, amount of training-induced improvement on the Rhythmic Weight Shift test in TBI patients was positively correlated with amount of change in fractional anisotropy in the inferior cerebellar peduncle. This suggests that training-induced plastic changes in balance control are associated with alterations in the cerebellar white matter microstructure in TBI patients. PMID:25610786

MRI Sequences in Head & Neck Radiology - State of the Art.

PubMed

Widmann, Gerlig; Henninger, Benjamin; Kremser, Christian; Jaschke, Werner

2017-05-01

Background  Magnetic resonance imaging (MRI) has become an essential imaging modality for the evaluation of head & neck pathologies. However, the diagnostic power of MRI is strongly related to the appropriate selection and interpretation of imaging protocols and sequences. The aim of this article is to review state-of-the-art sequences for the clinical routine in head & neck MRI and to describe the evidence for which medical question these sequences and techniques are useful. Method  Literature review of state-of-the-art sequences in head & neck MRI. Results and Conclusion  Basic sequences (T1w, T2w, T1wC+) and fat suppression techniques (TIRM/STIR, Dixon, Spectral Fat sat) are important tools in the diagnostic workup of inflammation, congenital lesions and tumors including staging. Additional sequences (SSFP (CISS, FIESTA), SPACE, VISTA, 3D-FLAIR) are used for pathologies of the cranial nerves, labyrinth and evaluation of endolymphatic hydrops in Menière's disease. Vessel and perfusion sequences (3D-TOF, TWIST/TRICKS angiography, DCE) are used in vascular contact syndromes, vascular malformations and analysis of microvascular parameters of tissue perfusion. Diffusion-weighted imaging (EPI-DWI, non-EPI-DWI, RESOLVE) is helpful in cholesteatoma imaging, estimation of malignancy, and evaluation of treatment response and posttreatment recurrence in head & neck cancer. Understanding of MRI sequences and close collaboration with referring physicians improves the diagnostic confidence of MRI in the daily routine and drives further research in this fascinating image modality. Key Points:   · Understanding of MRI sequences is essential for the correct and reliable interpretation of MRI findings.. · MRI protocols have to be carefully selected based on relevant clinical information.. · Close collaboration with referring physicians improves the output obtained from the diagnostic possibilities of MRI.. Citation Format · Widmann G, Henninger B, Kremser C et al. MRI Sequences in Head & Neck Radiology - State of the Art. Fortschr Röntgenstr 2017; 189: 413 - 422. © Georg Thieme Verlag KG Stuttgart · New York.

Multi-site study of diffusion metric variability: effects of site, vendor, field strength, and echo time on regions-of-interest and histogram-bin analyses.

PubMed

Helmer, K G; Chou, M-C; Preciado, R I; Gimi, B; Rollins, N K; Song, A; Turner, J; Mori, S

2016-02-27

It is now common for magnetic-resonance-imaging (MRI) based multi-site trials to include diffusion-weighted imaging (DWI) as part of the protocol. It is also common for these sites to possess MR scanners of different manufacturers, different software and hardware, and different software licenses. These differences mean that scanners may not be able to acquire data with the same number of gradient amplitude values and number of available gradient directions. Variability can also occur in achievable b-values and minimum echo times. The challenge of a multi-site study then, is to create a common protocol by understanding and then minimizing the effects of scanner variability and identifying reliable and accurate diffusion metrics. This study describes the effect of site, scanner vendor, field strength, and TE on two diffusion metrics: the first moment of the diffusion tensor field (mean diffusivity, MD), and the fractional anisotropy (FA) using two common analyses (region-of-interest and mean-bin value of whole brain histograms). The goal of the study was to identify sources of variability in diffusion-sensitized imaging and their influence on commonly reported metrics. The results demonstrate that the site, vendor, field strength, and echo time all contribute to variability in FA and MD, though to different extent. We conclude that characterization of the variability of DTI metrics due to site, vendor, field strength, and echo time is a worthwhile step in the construction of multi-center trials.

Mean apparent propagator (MAP) MRI: a novel diffusion imaging method for mapping tissue microstructure.

PubMed

Özarslan, Evren; Koay, Cheng Guan; Shepherd, Timothy M; Komlosh, Michal E; İrfanoğlu, M Okan; Pierpaoli, Carlo; Basser, Peter J

2013-09-01

Diffusion-weighted magnetic resonance (MR) signals reflect information about underlying tissue microstructure and cytoarchitecture. We propose a quantitative, efficient, and robust mathematical and physical framework for representing diffusion-weighted MR imaging (MRI) data obtained in "q-space," and the corresponding "mean apparent propagator (MAP)" describing molecular displacements in "r-space." We also define and map novel quantitative descriptors of diffusion that can be computed robustly using this MAP-MRI framework. We describe efficient analytical representation of the three-dimensional q-space MR signal in a series expansion of basis functions that accurately describes diffusion in many complex geometries. The lowest order term in this expansion contains a diffusion tensor that characterizes the Gaussian displacement distribution, equivalent to diffusion tensor MRI (DTI). Inclusion of higher order terms enables the reconstruction of the true average propagator whose projection onto the unit "displacement" sphere provides an orientational distribution function (ODF) that contains only the orientational dependence of the diffusion process. The representation characterizes novel features of diffusion anisotropy and the non-Gaussian character of the three-dimensional diffusion process. Other important measures this representation provides include the return-to-the-origin probability (RTOP), and its variants for diffusion in one- and two-dimensions-the return-to-the-plane probability (RTPP), and the return-to-the-axis probability (RTAP), respectively. These zero net displacement probabilities measure the mean compartment (pore) volume and cross-sectional area in distributions of isolated pores irrespective of the pore shape. MAP-MRI represents a new comprehensive framework to model the three-dimensional q-space signal and transform it into diffusion propagators. Experiments on an excised marmoset brain specimen demonstrate that MAP-MRI provides several novel, quantifiable parameters that capture previously obscured intrinsic features of nervous tissue microstructure. This should prove helpful for investigating the functional organization of normal and pathologic nervous tissue. Copyright © 2013 Elsevier Inc. All rights reserved.

Measurement and modeling of diffusion time dependence of apparent diffusion coefficient and fractional anisotropy in prostate tissue ex vivo.

PubMed

Bourne, Roger; Liang, Sisi; Panagiotaki, Eleftheria; Bongers, Andre; Sved, Paul; Watson, Geoffrey

2017-10-01

The purpose of this study was to measure and model the diffusion time dependence of apparent diffusion coefficient (ADC) and fractional anisotropy (FA) derived from conventional prostate diffusion-weighted imaging methods as used in recommended multiparametric MRI protocols. Diffusion tensor imaging (DTI) was performed at 9.4 T with three radical prostatectomy specimens, with diffusion times in the range 10-120 ms and b-values 0-3000 s/mm 2 . ADC and FA were calculated from DTI measurements at b-values of 800 and 1600 s/mm 2 . Independently, a two-component model (restricted isotropic plus Gaussian anisotropic) was used to synthesize DTI data, from which ADC and FA were predicted and compared with the measured values. Measured ADC and FA exhibited a diffusion time dependence, which was closely predicted by the two-component model. ADC decreased by about 0.10-0.15 μm 2 /ms as diffusion time increased from 10 to 120 ms. FA increased with diffusion time at b-values of 800 and 1600 s/mm 2 but was predicted to be independent of diffusion time at b = 3000 s/mm 2 . Both ADC and FA exhibited diffusion time dependence that could be modeled as two unmixed water pools - one having isotropic restricted dynamics, and the other unrestricted anisotropic dynamics. These results highlight the importance of considering and reporting diffusion times in conventional ADC and FA calculations and protocol recommendations, and inform the development of improved diffusion methods for prostate cancer imaging. Copyright © 2017 John Wiley & Sons, Ltd.

Metastatic Renal Cell Carcinoma Masquerading as Jugular Foramen Paraganglioma: A Role for Novel Magnetic Resonance Imaging.

PubMed

Thomas, Andrew J; Wiggins, Richard H; Gurgel, Richard K

2017-08-01

To describe a case of metastatic renal cell carcinoma (RCC) masquerading as a jugular foramen paraganglioma (JP). To compare imaging findings between skull base metastatic RCC and histologically proven paraganglioma. A case of unexpected metastatic skull base RCC is reviewed. Computed tomography (CT) and magnetic resonance imaging (MRI) were compared between 3 confirmed cases of JP and our case of metastatic RCC. Diffusion-weighted MRI (DW-MRI) sequences and computed apparent diffusion coefficient (ADC) values were compared between these entities. A 55-year-old man presents with what appears clinically and radiographically to be JP. The tumor was resected, then discovered on postoperative pathology to be metastatic RCC. Imaging was retrospectively compared between 3 histologically confirmed cases of JP and our case of skull base RCC. The RCC metastasis was indistinguishable from JP on CT and traditional MRI but distinct by ADC values calculated from DW-MRI. Metastatic RCC at the skull base may mimic the clinical presentation and radiographic appearance of JP. The MRI finding of flow voids is seen in both paraganglioma and metastatic RCC. Diffusion-weighted MRI is able to distinguish these entities, highlighting its potential utility in distinguishing skull base lesions.

[Effect of vibration caused by time-varying magnetic fields on diffusion-weighted MRI].

PubMed

Ogura, Akio; Maeda, Fumie; Miyai, Akira; Hayashi, Kohji; Hongoh, Takaharu

2006-04-20

Diffusion-weighted images (DWIs) with high b-factor in the body are often used to detect and diagnose cancer at MRI. The echo planar imaging (EPI) sequence and high motion probing gradient pulse are used at diffusion weighted imaging, causing high table vibration. The purpose of this study was to assess whether the diffusion signal and apparent diffusion coefficient (ADC) values are influenced by this vibration because of time-varying magnetic fields. Two DWIs were compared. In one, phantoms were fixed on the MRI unit's table transmitting the vibration. In the other, phantoms were supported in air, in the absence of vibration. The phantoms called "solution phantoms" were made from agarose of a particular density. The phantoms called "jelly phantoms" were made from agarose that was heated. The diffusion signal and ADC value of each image were compared. The results showed that the signal of DWI units using the solution phantom was not affected by vibration. However, the signal of DWI and ADC were increased in the low-density jelly phantom as a result of vibration, causing the jelly phantom to vibrate. The DWIs of vibrating regions such as the breast maybe be subject to error. A countermeasure seems to be to support the region adequately.

Characterization of the collagen component of cartilage repair tissue of the talus with quantitative MRI: comparison of T2 relaxation time measurements with a diffusion-weighted double-echo steady-state sequence (dwDESS).

PubMed

Kretzschmar, M; Bieri, O; Miska, M; Wiewiorski, M; Hainc, N; Valderrabano, V; Studler, U

2015-04-01

The purpose of this study was to characterize the collagen component of repair tissue (RT) of the talus after autologous matrix-induced chondrogenesis (AMIC) using quantitative T2 and diffusion-weighted imaging. Mean T2 values and diffusion coefficients of AMIC-RT and normal cartilage of the talus of 25 patients with posttraumatic osteochondral lesions and AMIC repair were compared in a cross-sectional design using partially spoiled steady-state free precession (pSSFP) for T2 quantification, and diffusion-weighted double-echo steady-state (dwDESS) for diffusion measurement. RT and cartilage were graded with modified Noyes and MOCART scores on morphological sequences. An association between follow-up interval and quantitative MRI measures was assessed using multivariate regression, after stratifying the cohort according to time interval between surgery and MRI. Mean T2 of the AMIC-RT and cartilage were 43.1 ms and 39.1 ms, respectively (p = 0.26). Mean diffusivity of the RT (1.76 μm(2)/ms) was significantly higher compared to normal cartilage (1.46 μm(2)/ms) (p = 0.0092). No correlation was found between morphological and quantitative parameters. RT diffusivity was lowest in the subgroup with follow-up >28 months (p = 0.027). Compared to T2-mapping, dwDESS demonstrated greater sensitivity in detecting differences in the collagen matrix between AMIC-RT and cartilage. Decreased diffusivity in patients with longer follow-up times may indicate an increased matrix organization of RT. • MRI is used to assess morphology of the repair tissue during follow-up. • Quantitative MRI allows an estimation of biochemical properties of the repair tissue. • Differences between repair tissue and cartilage were more significant with dwDESS than T2 mapping.

Diffusion-weighted MRI monitoring of pancreatic cancer response to radiofrequency heat-enhanced intratumor chemotherapy.

PubMed

Zhang, Tong; Zhang, Feng; Meng, Yanfeng; Wang, Han; Le, Thomas; Wei, Baojie; Lee, Donghoon; Willis, Patrick; Shen, Baozhong; Yang, Xiaoming

2013-12-01

The aim of this study was to evaluate the feasibility of using diffusion-weighted MRI to monitor the early response of pancreatic cancers to radiofrequency heat (RFH)-enhanced chemotherapy. Human pancreatic carcinoma cells (PANC-1) in different groups and 24 mice with pancreatic cancer xenografts in four groups were treated with phosphate-buffered saline (PBS) as a control, RFH at 42 °C, gemcitabine and gemcitabine plus RFH at 42 °C. One day before and 1, 7 and 14 days after treatment, diffusion-weighted MRI and T2 -weighted imaging were applied to monitor the apparent diffusion coefficients (ADCs) of tumors and tumor growth. MRI findings were correlated with the results of tumor apoptosis analysis. In the in vitro experiments, the quantitative viability assay showed lower relative cell viabilities for treatment with gemcitabine plus RFH at 42 °C relative to treatment with RFH only and gemcitabine only (37 ± 5% versus 65 ± 4% and 58 ± 8%, respectively, p < 0.05). In the in vivo experiments, the combination therapy resulted in smaller relative tumor volumes than RFH only and chemotherapy only (0.82 ± 0.17 versus 2.23 ± 0.90 and 1.64 ± 0.44, respectively, p = 0.003). In vivo, 14-T MRI demonstrated a remarkable decrease in ADCs at day 1 and increased ADCs at days 7 and 14 in the combination therapy group. The apoptosis index in the combination therapy group was significantly higher than those in the chemotherapy-only, RFH-only and PBS treatment groups (37 ± 6% versus 20 ± 5%, 8 ± 2% and 3 ± 1%, respectively, p < 0.05). This study confirms that it is feasible to use MRI to monitor RFH-enhanced chemotherapy in pancreatic cancers, which may present new options for the efficient treatment of pancreatic malignancies using MRI/RFH-integrated local chemotherapy. Copyright © 2013 John Wiley & Sons, Ltd.

Assessing the multiscale architecture of muscular tissue with Q-space magnetic resonance imaging: Review.

PubMed

Hoffman, Matthew P; Taylor, Erik N; Aninwene, George E; Sadayappan, Sakthivel; Gilbert, Richard J

2018-02-01

Contraction of muscular tissue requires the synchronized shortening of myofibers arrayed in complex geometrical patterns. Imaging such myofiber patterns with diffusion-weighted MRI reveals architectural ensembles that underlie force generation at the organ scale. Restricted proton diffusion is a stochastic process resulting from random translational motion that may be used to probe the directionality of myofibers in whole tissue. During diffusion-weighted MRI, magnetic field gradients are applied to determine the directional dependence of proton diffusion through the analysis of a diffusional probability distribution function (PDF). The directions of principal (maximal) diffusion within the PDF are associated with similarly aligned diffusion maxima in adjacent voxels to derive multivoxel tracts. Diffusion-weighted MRI with tractography thus constitutes a multiscale method for depicting patterns of cellular organization within biological tissues. We provide in this review, details of the method by which generalized Q-space imaging is used to interrogate multidimensional diffusion space, and thereby to infer the organization of muscular tissue. Q-space imaging derives the lowest possible angular separation of diffusion maxima by optimizing the conditions by which magnetic field gradients are applied to a given tissue. To illustrate, we present the methods and applications associated with Q-space imaging of the multiscale myoarchitecture associated with the human and rodent tongues. These representations emphasize the intricate and continuous nature of muscle fiber organization and suggest a method to depict structural "blueprints" for skeletal and cardiac muscle tissue. © 2016 Wiley Periodicals, Inc.

TU-F-CAMPUS-J-02: Evaluation of Textural Feature Extraction for Radiotherapy Response Assessment of Early Stage Breast Cancer Patients Using Diffusion Weighted MRI and Dynamic Contrast Enhanced MRI

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

Xie, Y; Wang, C; Horton, J

Purpose: To investigate the feasibility of using classic textural feature extraction in radiotherapy response assessment, we studied a unique cohort of early stage breast cancer patients with paired pre - and post-radiation Diffusion Weighted MRI (DWI-MRI) and Dynamic Contrast Enhanced MRI (DCE-MRI). Methods: 15 female patients from our prospective phase I trial evaluating preoperative radiotherapy were included in this retrospective study. Each patient received a single-fraction radiation treatment, and DWI and DCE scans were conducted before and after the radiotherapy. DWI scans were acquired using a spin-echo EPI sequence with diffusion weighting factors of b = 0 and b =more » 500 mm{sup 2} /s, and the apparent diffusion coefficient (ADC) maps were calculated. DCE-MRI scans were acquired using a T{sub 1}-weighted 3D SPGR sequence with a temporal resolution of about 1 minute. The contrast agent (CA) was intravenously injected with a 0.1 mmol/kg bodyweight dose at 2 ml/s. Two parameters, volume transfer constant (K{sup trans} ) and k{sub ep} were analyzed using the two-compartment Tofts kinetic model. For DCE parametric maps and ADC maps, 33 textural features were generated from the clinical target volume (CTV) in a 3D fashion using the classic gray level co-occurrence matrix (GLCOM) and gray level run length matrix (GLRLM). Wilcoxon signed-rank test was used to determine the significance of each texture feature’s change after the radiotherapy. The significance was set to 0.05 with Bonferroni correction. Results: For ADC maps calculated from DWI-MRI, 24 out of 33 CTV features changed significantly after the radiotherapy. For DCE-MRI pharmacokinetic parameters, all 33 CTV features of K{sup trans} and 33 features of k{sub ep} changed significantly. Conclusion: Initial results indicate that those significantly changed classic texture features are sensitive to radiation-induced changes and can be used for assessment of radiotherapy response in breast cancer.« less

Transcortical Sensory Aphasia after Left Frontal Lobe Infarction: Loss of Functional Connectivity.

PubMed

Kwon, Miseon; Shim, Woo Hyun; Kim, Sang-Joon; Kim, Jong S

2017-01-01

The underlying mechanism of transcortical sensory aphasia (TSA) caused by lesions occurring in the left frontal lobe remains unclear. We attempted to investigate the mechanism with the use of functional MRI (fMRI). We studied 2 patients with TSA after a left frontal infarction identified by diffusion-weighted MRI. As control subjects, a patient with transcortical motor aphasia and a healthy normal adult were chosen. The Korean version of Western Aphasia Battery was performed initially and at 3 months post stroke. We performed fMRI using verb generation and sentence completion tasks. Resting-state fMRI (rs-fMRI) was also obtained for network-level analysis initially and at 3 months post stroke. The results of diffusion- and perfusion-weighted MRI revealed no diffusion-perfusion mismatch. Initial fMRI in patients with TSA showed no reversed inter-/intrahemispheric activation patterns. rs-fMRI showed significantly decreased resting-state functional connectivity in the language network in patients with TSA compared with the control subjects. Follow-up rs-fMRI studies showed improvement in functional connectivity along with the recovery of patients' language function. Our data showed that the auditory comprehension deficits in patients with frontal lobe infarcts is attributed to difficulty accessing the posterior language area due to functional disconnection between language centers in the acute stage of stroke. © 2017 S. Karger AG, Basel.

Diffusion weighted imaging reflects variable cellularity and stromal density present in breast fibroadenomas

PubMed Central

Parsian, Sana; Giannakopoulos, Nadia V.; Rahbar, Habib; Rendi, Mara H.; Chai, Xiaoyu

2016-01-01

OBJECTIVE To determine the underlying histopathologic features influencing apparent diffusion coefficient (ADC) values of breast fibroadenomas. MATERIALS AND METHODS Biopsy proven fibroadenomas (n=26) initially identified as suspicious on breast MRI were retrospectively evaluated. Histopathological assessments of lesion cellularity and stromal type were compared with ADC measures on diffusion-weighted MRI. RESULTS Presence of epithelial hyperplasia (increased cellularity) and dense collagenous stroma were both significantly associated with lower lesion ADC values (p=0.02 and 0.004, respectively. CONCLUSION Variations in epithelial cellularity and stromal type influence breast lesion ADC values and may explain the wide range of ADC measures observed in benign fibroadenomas. PMID:27379441

The role of diffusion-weighted MR imaging for differentiating benign from malignant bile duct strictures.

PubMed

Park, Hyun Jeong; Kim, Seong Hyun; Jang, Kyung Mi; Choi, Seo-youn; Lee, Soon Jin; Choi, Dongil

2014-04-01

To assess the added value of diffusion-weighted imaging (DWI) to conventional magnetic resonance imaging (MRI) for differentiating benign from malignant bile duct strictures. Twenty-seven patients with a benign stricture and 42 patients with a malignant stricture who had undergone gadoxetic acid-enhanced MRI with DWI were enrolled. Qualitative (signal intensity, dynamic enhancement pattern) and quantitative (wall thickness and length) analyses were performed. Two observers independently reviewed a set of conventional MRI and a combined set of conventional MRI and DWI, and receiver operating characteristic (ROC) curve analysis was assessed. Benign strictures showed isointensity (18.5-70.4 %) and a similar enhancement pattern (22.2 %) to that of normal bile duct more frequently than malignant strictures (0-40.5 % and 0 %) on conventional MRI (P < 0.05). Malignant strictures (90.5-92.9 %) showed hypervascularity on arterial and portal venous phase images more frequently than benign strictures (37.0-70.4 %) (P < 0.01) On DWI, all malignant strictures showed hyperintensity compared with benign cases (70.4 %) (P < 0.001). Malignant strictures were significantly thicker and longer than benign strictures (P < 0.001). The diagnostic performance of both observers improved significantly after additional review of DWI. Adding DWI to conventional MRI is more helpful for differentiating benign from malignant bile duct strictures than conventional MRI alone. • Accurate diagnosis and exclusion of benign strictures of bile duct are important. • Diffusion-weighted MRI helps to distinguish benign from malignant bile duct strictures. • DWI plus conventional MRI provides superior diagnostic accuracy to conventional MRI alone.

Extended T2-IVIM model for correction of TE dependence of pseudo-diffusion volume fraction in clinical diffusion-weighted magnetic resonance imaging

NASA Astrophysics Data System (ADS)

Jerome, N. P.; d'Arcy, J. A.; Feiweier, T.; Koh, D.-M.; Leach, M. O.; Collins, D. J.; Orton, M. R.

2016-12-01

The bi-exponential intravoxel-incoherent-motion (IVIM) model for diffusion-weighted MRI (DWI) fails to account for differential T 2 s in the model compartments, resulting in overestimation of pseudodiffusion fraction f. An extended model, T2-IVIM, allows removal of the confounding echo-time (TE) dependence of f, and provides direct compartment T 2 estimates. Two consented healthy volunteer cohorts (n  =  5, 6) underwent DWI comprising multiple TE/b-value combinations (Protocol 1: TE  =  62-102 ms, b  =  0-250 mm-2s, 30 combinations. Protocol 2: 8 b-values 0-800 mm-2s at TE  =  62 ms, with 3 additional b-values 0-50 mm-2s at TE  =  80, 100 ms scanned twice). Data from liver ROIs were fitted with IVIM at individual TEs, and with the T2-IVIM model using all data. Repeat-measures coefficients of variation were assessed for Protocol 2. Conventional IVIM modelling at individual TEs (Protocol 1) demonstrated apparent f increasing with longer TE: 22.4  ±  7% (TE  =  62 ms) to 30.7  ±  11% (TE  =  102 ms) T2-IVIM model fitting accounted for all data variation. Fitting of Protocol 2 data using T2-IVIM yielded reduced f estimates (IVIM: 27.9  ±  6%, T2-IVIM: 18.3  ±  7%), as well as T 2  =  42.1  ±  7 ms, 77.6  ±  30 ms for true and pseudodiffusion compartments, respectively. A reduced Protocol 2 dataset yielded comparable results in a clinical time frame (11 min). The confounding dependence of IVIM f on TE can be accounted for using additional b/TE images and the extended T2-IVIM model.

Unilateral or bilateral punctate hippocampal hyperintensities on DW-MRI: seizures, amnesia, or both?

PubMed

Bocos-Portillo, Jone; Escalza-Cortina, Inés; Gómez-Beldarrain, Marian; Rodriguez-Sainz, Aida; Garcia-Monco, Juan Carlos

2018-06-02

The presence of small hippocampal hyperintense lesions on diffusion-weighted (DW) MRI can respond to different etiologies and represents a challenge where clinical judgment is imperative, since therapeutic approach may be quite different.We here report three patients with similar neuroradiological findings, i.e., hyperintense punctate hippocampal lesions on diffusion-weighted MRI sequences, yet of different origin. The first one presented with isolated amnesia (transient global amnesia), the second one with amnesia and seizures, and the third one with seizures.Thus, hippocampal punctate lesions appear after transient global amnesia, but the same pattern may be present after seizures, either focal-onset or generalized seizures. This peculiar radiological MRI pattern could indicate a pathogenic link between transient global amnesia (TGA) and seizures which should be further studied.

Prenatal MR imaging of a meconium pseudocyst extending to the right subphrenic space with right lung compression.

PubMed

Wong, Alex M; Toh, Cheng-Hong; Lien, Reyin; Chao, An-Shine; Wong, Ho-Fai; Ng, Koon-Kwan

2006-11-01

Meconium pseudocyst results from a loculated inflammation occurring in response to spillage of meconium into the peritoneal cavity after a bowel perforation. Certain cystic lesions, such as abscesses and dermoid and epidermoid cysts, are known to show reduced water diffusion on DWI. MRI has recently become a valuable adjunct to ultrasonography for fetal gastrointestinal anomalies. Complementary to ultrasonography, prenatal MRI can help further characterize the lesion and can clearly demonstrate the anatomical relationship between the lesion and adjacent organs. We report a case of meconium pseudocyst that was prenatally imaged with ultrasonography and MRI, postnatally complicated by pneumoperitoneum, and proved by postnatal surgery and histopathology. We emphasize the MRI of the pseudocyst, particularly T1-weighted and diffusion-weighted imaging.

Aggressive Angiomyxoma with Diffusion-Weighted Magnetic Resonance Imaging and Dynamic Contrast Enhancement: A Case Report and Review of the Literature

PubMed Central

Brunelle, S.; Bertucci, F.; Chetaille, B.; Lelong, B.; Piana, G.; Sarran, A.

2013-01-01

Introduction Aggressive angiomyxoma (AA) is a rare benign soft tissue tumour usually affecting the pelvis and perineum of young women. Magnetic resonance imaging (MRI) is crucial in the management of AA patients for its diagnostic contribution and for the preoperative assessment of the actual tumour extension. Given the current development of less aggressive therapeutics associated with a higher risk of recurrence, close follow-up with MRI is fundamental after treatment. In this context, diffusion-weighted (DW) imaging has already shown high efficacy in the detection of early small relapses in prostate or rectal cancer. Case Report We report here a case of pelvic AA in a 51-year-old woman examined with dynamic contrast enhancement and DW-MRI, including apparent diffusion coefficient mapping and calculation. Conclusion To our knowledge, this is the first description of DW-MRI in AA reported in the literature. Here, knowledge about imaging features of AA will be reviewed and expanded. PMID:23904848

Aggressive angiomyxoma with diffusion-weighted magnetic resonance imaging and dynamic contrast enhancement: a case report and review of the literature.

PubMed

Brunelle, S; Bertucci, F; Chetaille, B; Lelong, B; Piana, G; Sarran, A

2013-05-01

Aggressive angiomyxoma (AA) is a rare benign soft tissue tumour usually affecting the pelvis and perineum of young women. Magnetic resonance imaging (MRI) is crucial in the management of AA patients for its diagnostic contribution and for the preoperative assessment of the actual tumour extension. Given the current development of less aggressive therapeutics associated with a higher risk of recurrence, close follow-up with MRI is fundamental after treatment. In this context, diffusion-weighted (DW) imaging has already shown high efficacy in the detection of early small relapses in prostate or rectal cancer. We report here a case of pelvic AA in a 51-year-old woman examined with dynamic contrast enhancement and DW-MRI, including apparent diffusion coefficient mapping and calculation. To our knowledge, this is the first description of DW-MRI in AA reported in the literature. Here, knowledge about imaging features of AA will be reviewed and expanded.

Rocky Mountain spotted fever: 'starry sky' appearance with diffusion-weighted imaging in a child.

PubMed

Crapp, Seth; Harrar, Dana; Strother, Megan; Wushensky, Curtis; Pruthi, Sumit

2012-04-01

We present a case of Rocky Mountain spotted fever encephalitis in a child imaged utilizing diffusion-weighted MRI. Although the imaging and clinical manifestations of this entity have been previously described, a review of the literature did not reveal any such cases reported in children utilizing diffusion-weighted imaging. The imaging findings and clinical history are presented as well as a brief review of this disease.

Spatially constrained incoherent motion method improves diffusion-weighted MRI signal decay analysis in the liver and spleen

PubMed Central

Taimouri, Vahid; Afacan, Onur; Perez-Rossello, Jeannette M.; Callahan, Michael J.; Mulkern, Robert V.; Warfield, Simon K.; Freiman, Moti

2015-01-01

Purpose: To evaluate the effect of the spatially constrained incoherent motion (SCIM) method on improving the precision and robustness of fast and slow diffusion parameter estimates from diffusion-weighted MRI in liver and spleen in comparison to the independent voxel-wise intravoxel incoherent motion (IVIM) model. Methods: We collected diffusion-weighted MRI (DW-MRI) data of 29 subjects (5 healthy subjects and 24 patients with Crohn’s disease in the ileum). We evaluated parameters estimates’ robustness against different combinations of b-values (i.e., 4 b-values and 7 b-values) by comparing the variance of the estimates obtained with the SCIM and the independent voxel-wise IVIM model. We also evaluated the improvement in the precision of parameter estimates by comparing the coefficient of variation (CV) of the SCIM parameter estimates to that of the IVIM. Results: The SCIM method was more robust compared to IVIM (up to 70% in liver and spleen) for different combinations of b-values. Also, the CV values of the parameter estimations using the SCIM method were significantly lower compared to repeated acquisition and signal averaging estimated using IVIM, especially for the fast diffusion parameter in liver (CVIV IM = 46.61 ± 11.22, CVSCIM = 16.85 ± 2.160, p < 0.001) and spleen (CVIV IM = 95.15 ± 19.82, CVSCIM = 52.55 ± 1.91, p < 0.001). Conclusions: The SCIM method characterizes fast and slow diffusion more precisely compared to the independent voxel-wise IVIM model fitting in the liver and spleen. PMID:25832079

Accuracy of magnetic resonance imaging in differentiating between benign and malignant vertebral lesions: role of diffusion-weighted imaging, in-phase/opposed-phase imaging and apparent diffusion coefficient.

PubMed

Martel Villagrán, J; Bueno Horcajadas, Á; Pérez Fernández, E; Martín Martín, S

2015-01-01

To determine the ability of MRI to distinguish between benign and malignant vertebral lesions. We included 85 patients and studied a total of 213 vertebrae (both pathologic and normal). For each vertebra, we determined whether the lesion was hypointense in T1-weighted sequences and whether it was hyperintense in STIR and in diffusion-weighted sequences. We calculated the in-phase/out-of-phase quotient and the apparent diffusion coefficient for each vertebra. We combined parameters from T1-weighted, diffusion-weighted, and STIR sequences to devise a formula to distinguish benign from malignant lesions. The group comprised 60 (70.6%) women and 25 (29.4%) men with a mean age of 67±13.5 years (range, 33-90 y). Of the 85 patients, 26 (30.6%) had a known primary tumor. When the lesion was hypointense on T1-weighted sequences, hyperintense on STIR and diffusion-weighted sequences, and had a signal intensity quotient greater than 0.8, the sensitivity was 97.2%, the specificity was 90%, and the diagnostic accuracy was 91.2%. If the patient had a known primary tumor, these values increased to 97.2%, 99.4%, and 99%, respectively. Benign lesions can be distinguished from malignant lesions if we combine the information from T1-weighted, STIR, and diffusion-weighted sequences together with the in-phase/out-of-phase quotient of the lesion detected in the vertebral body on MRI. Copyright © 2013 SERAM. Published by Elsevier España, S.L.U. All rights reserved.

Relative diffusion of paramagnetic metal complexes of MRI contrast agents in an isotropic hydrogel medium.

PubMed

Weerakoon, Bimali Sanjeevani; Osuga, Toshiaki

2017-03-01

The observation of molecular diffusion by means of magnetic resonance imaging (MRI) is significant in the evaluation of the metabolic activity of living tissues. Series of MRI examinations were conducted on a diffusion model to study the behaviour of the diffusion process of different-molecular-weight (MW) paramagnetic MRI contrast agents in an isotropic agar hydrogel medium. The model consisted of a solidified 1 % agar gel with an initial concentration of 0.5 mmol/L contrast solution layered on top of the gel. The diffusion process was monitored at pre-determined time intervals of immediately, 1, 6, 9, 23, and 48 h after introduction of the contrast agents onto the agar gel with a T1-weighted spin-echo (SE) pulse sequence. Three types of paramagnetic contrast agents, Gd-DTPA with a MW of 547.57 g/mol, Prohance with a MW of 558.69 g/mol and MnCl 2 with a MW of 125.84 g/mol, resulted in an approximate average diffusional displacement ratio of 1:1:2 per hour, respectively, within 48 h of the experiment. Therefore, the results of this study supported the hypothesis that the rate of the diffusion process of MRI contrast agents in the agar hydrogel medium is inversely related to their MWs. However, more repetitions are necessary under various types of experimental conditions and also with various types of contrast media of different MWs for further confirmation and validation of these results.

Diffusion MRI in the heart

PubMed Central

Mekkaoui, Choukri; Reese, Timothy G.; Jackowski, Marcel P.; Bhat, Himanshu

2015-01-01

Diffusion MRI provides unique information on the structure, organization, and integrity of the myocardium without the need for exogenous contrast agents. Diffusion MRI in the heart, however, has proven technically challenging because of the intrinsic non‐rigid deformation during the cardiac cycle, displacement of the myocardium due to respiratory motion, signal inhomogeneity within the thorax, and short transverse relaxation times. Recently developed accelerated diffusion‐weighted MR acquisition sequences combined with advanced post‐processing techniques have improved the accuracy and efficiency of diffusion MRI in the myocardium. In this review, we describe the solutions and approaches that have been developed to enable diffusion MRI of the heart in vivo, including a dual‐gated stimulated echo approach, a velocity‐ (M 1) or an acceleration‐ (M 2) compensated pulsed gradient spin echo approach, and the use of principal component analysis filtering. The structure of the myocardium and the application of these techniques in ischemic heart disease are also briefly reviewed. The advent of clinical MR systems with stronger gradients will likely facilitate the translation of cardiac diffusion MRI into clinical use. The addition of diffusion MRI to the well‐established set of cardiovascular imaging techniques should lead to new and complementary approaches for the diagnosis and evaluation of patients with heart disease. © 2015 The Authors. NMR in Biomedicine published by John Wiley & Sons Ltd. PMID:26484848

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

PubMed

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.

Removal of intensity bias in magnitude spin-echo MRI images by nonlinear diffusion filtering

NASA Astrophysics Data System (ADS)

Samsonov, Alexei A.; Johnson, Chris R.

2004-05-01

MRI data analysis is routinely done on the magnitude part of complex images. While both real and imaginary image channels contain Gaussian noise, magnitude MRI data are characterized by Rice distribution. However, conventional filtering methods often assume image noise to be zero mean and Gaussian distributed. Estimation of an underlying image using magnitude data produces biased result. The bias may lead to significant image errors, especially in areas of low signal-to-noise ratio (SNR). The incorporation of the Rice PDF into a noise filtering procedure can significantly complicate the method both algorithmically and computationally. In this paper, we demonstrate that inherent image phase smoothness of spin-echo MRI images could be utilized for separate filtering of real and imaginary complex image channels to achieve unbiased image denoising. The concept is demonstrated with a novel nonlinear diffusion filtering scheme developed for complex image filtering. In our proposed method, the separate diffusion processes are coupled through combined diffusion coefficients determined from the image magnitude. The new method has been validated with simulated and real MRI data. The new method has provided efficient denoising and bias removal in conventional and black-blood angiography MRI images obtained using fast spin echo acquisition protocols.

The Marburg-Münster Affective Disorders Cohort Study (MACS): A quality assurance protocol for MR neuroimaging data.

PubMed

Vogelbacher, Christoph; Möbius, Thomas W D; Sommer, Jens; Schuster, Verena; Dannlowski, Udo; Kircher, Tilo; Dempfle, Astrid; Jansen, Andreas; Bopp, Miriam H A

2018-05-15

Large, longitudinal, multi-center MR neuroimaging studies require comprehensive quality assurance (QA) protocols for assessing the general quality of the compiled data, indicating potential malfunctions in the scanning equipment, and evaluating inter-site differences that need to be accounted for in subsequent analyses. We describe the implementation of a QA protocol for functional magnet resonance imaging (fMRI) data based on the regular measurement of an MRI phantom and an extensive variety of currently published QA statistics. The protocol is implemented in the MACS (Marburg-Münster Affective Disorders Cohort Study, http://for2107.de/), a two-center research consortium studying the neurobiological foundations of affective disorders. Between February 2015 and October 2016, 1214 phantom measurements have been acquired using a standard fMRI protocol. Using 444 healthy control subjects which have been measured between 2014 and 2016 in the cohort, we investigate the extent of between-site differences in contrast to the dependence on subject-specific covariates (age and sex) for structural MRI, fMRI, and diffusion tensor imaging (DTI) data. We show that most of the presented QA statistics differ severely not only between the two scanners used for the cohort but also between experimental settings (e.g. hardware and software changes), demonstrate that some of these statistics depend on external variables (e.g. time of day, temperature), highlight their strong dependence on proper handling of the MRI phantom, and show how the use of a phantom holder may balance this dependence. Site effects, however, do not only exist for the phantom data, but also for human MRI data. Using T1-weighted structural images, we show that total intracranial (TIV), grey matter (GMV), and white matter (WMV) volumes significantly differ between the MR scanners, showing large effect sizes. Voxel-based morphometry (VBM) analyses show that these structural differences observed between scanners are most pronounced in the bilateral basal ganglia, thalamus, and posterior regions. Using DTI data, we also show that fractional anisotropy (FA) differs between sites in almost all regions assessed. When pooling data from multiple centers, our data show that it is a necessity to account not only for inter-site differences but also for hardware and software changes of the scanning equipment. Also, the strong dependence of the QA statistics on the reliable placement of the MRI phantom shows that the use of a phantom holder is recommended to reduce the variance of the QA statistics and thus to increase the probability of detecting potential scanner malfunctions. Copyright © 2018 Elsevier Inc. All rights reserved.

Readout-segmented multi-shot diffusion-weighted MRI of the knee joint in patients with juvenile idiopathic arthritis.

PubMed

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 differentiate non-inflamed joints from knee joints with mild synovial irritation.

"MASSIVE" brain dataset: Multiple acquisitions for standardization of structural imaging validation and evaluation.

PubMed

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

2017-05-01

In this work, we present the MASSIVE (Multiple Acquisitions for Standardization of Structural Imaging Validation and Evaluation) brain dataset of a single healthy subject, which is intended to facilitate diffusion MRI (dMRI) modeling and methodology development. MRI data of one healthy subject (female, 25 years) were acquired on a clinical 3 Tesla system (Philips Achieva) with an eight-channel head coil. In total, the subject was scanned on 18 different occasions with a total acquisition time of 22.5 h. The dMRI data were acquired with an isotropic resolution of 2.5 mm 3 and distributed over five shells with b-values up to 4000 s/mm 2 and two Cartesian grids with b-values up to 9000 s/mm 2 . The final dataset consists of 8000 dMRI volumes, corresponding B 0 field maps and noise maps for subsets of the dMRI scans, and ten three-dimensional FLAIR, T 1 -, and T 2 -weighted scans. The average signal-to-noise-ratio of the non-diffusion-weighted images was roughly 35. This unique set of in vivo MRI data will provide a robust framework to evaluate novel diffusion processing techniques and to reliably compare different approaches for diffusion modeling. The MASSIVE dataset is made publically available (both unprocessed and processed) on www.massive-data.org. Magn Reson Med 77:1797-1809, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 International Society for Magnetic Resonance in Medicine.

MRI diffusion-weighted imaging (DWI) in pediatric small bowel Crohn disease: correlation with MRI findings of active bowel wall inflammation.

PubMed

Ream, Justin M; Dillman, Jonathan R; Adler, Jeremy; Khalatbari, Shokoufeh; McHugh, Jonathan B; Strouse, Peter J; Dhanani, Muhammad; Shpeen, Benjamin; Al-Hawary, Mahmoud M

2013-09-01

Restricted diffusion on diffusion-weighted imaging (DWI) sequences during magnetic resonance enterography (MRE) has been shown in segments of bowel affected by Crohn disease. However, the exact meaning of this finding, particularly within the pediatric Crohn disease population, is poorly understood. The purpose of this study was to determine the significance of bowel wall restricted diffusion in children with small bowel Crohn disease by correlating apparent diffusion coefficient (ADC) values with other MRI markers of disease activity. A retrospective review of pediatric patients (≤ 18 years of age) with Crohn disease terminal ileitis who underwent MRE with DWI at our institution between May 1, 2009 and May 31, 2011 was undertaken. All of the children had either biopsy-proven Crohn disease terminal ileitis or clinically diagnosed Crohn disease, including terminal ileal involvement by imaging. The mean minimum ADC value within the wall of the terminal ileum was determined for each examination. ADC values were tested for correlation/association with other MRI findings to determine whether a relationship exists between bowel wall restricted diffusion and disease activity. Forty-six MRE examinations with DWI in children with terminal ileitis were identified (23 girls and 23 boys; mean age, 14.3 years). There was significant negative correlation or association between bowel wall minimum ADC value and established MRI markers of disease activity, including degree of bowel wall thickening (R = (-)0.43; P = 0.003), striated pattern of arterial enhancement (P = 0.01), degree of arterial enhancement (P = 0.01), degree of delayed enhancement (P = 0.045), amount of mesenteric inflammatory changes (P < 0.0001) and presence of a stricture (P = 0.02). ADC values were not significantly associated with bowel wall T2-weighted signal intensity, length of disease involvement or mesenteric fibrofatty proliferation. Increasing bowel wall restricted diffusion (lower ADC values) is associated with multiple MRI findings that are traditionally associated with active inflammation in pediatric small bowel Crohn disease.

Assessing the sensitivity of diffusion MRI to detect neuronal activity directly.

PubMed

Bai, Ruiliang; Stewart, Craig V; Plenz, Dietmar; Basser, Peter J

2016-03-22

Functional MRI (fMRI) is widely used to study brain function in the neurosciences. Unfortunately, conventional fMRI only indirectly assesses neuronal activity via hemodynamic coupling. Diffusion fMRI was proposed as a more direct and accurate fMRI method to detect neuronal activity, yet confirmative findings have proven difficult to obtain. Given that the underlying relation between tissue water diffusion changes and neuronal activity remains unclear, the rationale for using diffusion MRI to monitor neuronal activity has yet to be clearly established. Here, we studied the correlation between water diffusion and neuronal activity in vitro by simultaneous calcium fluorescence imaging and diffusion MR acquisition. We used organotypic cortical cultures from rat brains as a biological model system, in which spontaneous neuronal activity robustly emerges free of hemodynamic and other artifacts. Simultaneous fluorescent calcium images of neuronal activity are then directly correlated with diffusion MR signals now free of confounds typically encountered in vivo. Although a simultaneous increase of diffusion-weighted MR signals was observed together with the prolonged depolarization of neurons induced by pharmacological manipulations (in which cell swelling was demonstrated to play an important role), no evidence was found that diffusion MR signals directly correlate with normal spontaneous neuronal activity. These results suggest that, whereas current diffusion MR methods could monitor pathological conditions such as hyperexcitability, e.g., those seen in epilepsy, they do not appear to be sensitive or specific enough to detect or follow normal neuronal activity.

Assessing the sensitivity of diffusion MRI to detect neuronal activity directly

PubMed Central

Bai, Ruiliang; Stewart, Craig V.; Plenz, Dietmar; Basser, Peter J.

2016-01-01

Functional MRI (fMRI) is widely used to study brain function in the neurosciences. Unfortunately, conventional fMRI only indirectly assesses neuronal activity via hemodynamic coupling. Diffusion fMRI was proposed as a more direct and accurate fMRI method to detect neuronal activity, yet confirmative findings have proven difficult to obtain. Given that the underlying relation between tissue water diffusion changes and neuronal activity remains unclear, the rationale for using diffusion MRI to monitor neuronal activity has yet to be clearly established. Here, we studied the correlation between water diffusion and neuronal activity in vitro by simultaneous calcium fluorescence imaging and diffusion MR acquisition. We used organotypic cortical cultures from rat brains as a biological model system, in which spontaneous neuronal activity robustly emerges free of hemodynamic and other artifacts. Simultaneous fluorescent calcium images of neuronal activity are then directly correlated with diffusion MR signals now free of confounds typically encountered in vivo. Although a simultaneous increase of diffusion-weighted MR signals was observed together with the prolonged depolarization of neurons induced by pharmacological manipulations (in which cell swelling was demonstrated to play an important role), no evidence was found that diffusion MR signals directly correlate with normal spontaneous neuronal activity. These results suggest that, whereas current diffusion MR methods could monitor pathological conditions such as hyperexcitability, e.g., those seen in epilepsy, they do not appear to be sensitive or specific enough to detect or follow normal neuronal activity. PMID:26941239

Diffusion MRI in the heart.

PubMed

Mekkaoui, Choukri; Reese, Timothy G; Jackowski, Marcel P; Bhat, Himanshu; Sosnovik, David E

2017-03-01

Diffusion MRI provides unique information on the structure, organization, and integrity of the myocardium without the need for exogenous contrast agents. Diffusion MRI in the heart, however, has proven technically challenging because of the intrinsic non-rigid deformation during the cardiac cycle, displacement of the myocardium due to respiratory motion, signal inhomogeneity within the thorax, and short transverse relaxation times. Recently developed accelerated diffusion-weighted MR acquisition sequences combined with advanced post-processing techniques have improved the accuracy and efficiency of diffusion MRI in the myocardium. In this review, we describe the solutions and approaches that have been developed to enable diffusion MRI of the heart in vivo, including a dual-gated stimulated echo approach, a velocity- (M 1 ) or an acceleration- (M 2 ) compensated pulsed gradient spin echo approach, and the use of principal component analysis filtering. The structure of the myocardium and the application of these techniques in ischemic heart disease are also briefly reviewed. The advent of clinical MR systems with stronger gradients will likely facilitate the translation of cardiac diffusion MRI into clinical use. The addition of diffusion MRI to the well-established set of cardiovascular imaging techniques should lead to new and complementary approaches for the diagnosis and evaluation of patients with heart disease. © 2015 The Authors. NMR in Biomedicine published by John Wiley & Sons Ltd. © 2015 The Authors. NMR in Biomedicine published by John Wiley & Sons Ltd.

Introduction of a standardized multimodality image protocol for navigation-guided surgery of suspected low-grade gliomas.

PubMed

Mert, Aygül; Kiesel, Barbara; Wöhrer, Adelheid; Martínez-Moreno, Mauricio; Minchev, Georgi; Furtner, Julia; Knosp, Engelbert; Wolfsberger, Stefan; Widhalm, Georg

2015-01-01

OBJECT Surgery of suspected low-grade gliomas (LGGs) poses a special challenge for neurosurgeons due to their diffusely infiltrative growth and histopathological heterogeneity. Consequently, neuronavigation with multimodality imaging data, such as structural and metabolic data, fiber tracking, and 3D brain visualization, has been proposed to optimize surgery. However, currently no standardized protocol has been established for multimodality imaging data in modern glioma surgery. The aim of this study was therefore to define a specific protocol for multimodality imaging and navigation for suspected LGG. METHODS Fifty-one patients who underwent surgery for a diffusely infiltrating glioma with nonsignificant contrast enhancement on MRI and available multimodality imaging data were included. In the first 40 patients with glioma, the authors retrospectively reviewed the imaging data, including structural MRI (contrast-enhanced T1-weighted, T2-weighted, and FLAIR sequences), metabolic images derived from PET, or MR spectroscopy chemical shift imaging, fiber tracking, and 3D brain surface/vessel visualization, to define standardized image settings and specific indications for each imaging modality. The feasibility and surgical relevance of this new protocol was subsequently prospectively investigated during surgery with the assistance of an advanced electromagnetic navigation system in the remaining 11 patients. Furthermore, specific surgical outcome parameters, including the extent of resection, histological analysis of the metabolic hotspot, presence of a new postoperative neurological deficit, and intraoperative accuracy of 3D brain visualization models, were assessed in each of these patients. RESULTS After reviewing these first 40 cases of glioma, the authors defined a specific protocol with standardized image settings and specific indications that allows for optimal and simultaneous visualization of structural and metabolic data, fiber tracking, and 3D brain visualization. This new protocol was feasible and was estimated to be surgically relevant during navigation-guided surgery in all 11 patients. According to the authors' predefined surgical outcome parameters, they observed a complete resection in all resectable gliomas (n = 5) by using contour visualization with T2-weighted or FLAIR images. Additionally, tumor tissue derived from the metabolic hotspot showed the presence of malignant tissue in all WHO Grade III or IV gliomas (n = 5). Moreover, no permanent postoperative neurological deficits occurred in any of these patients, and fiber tracking and/or intraoperative monitoring were applied during surgery in the vast majority of cases (n = 10). Furthermore, the authors found a significant intraoperative topographical correlation of 3D brain surface and vessel models with gyral anatomy and superficial vessels. Finally, real-time navigation with multimodality imaging data using the advanced electromagnetic navigation system was found to be useful for precise guidance to surgical targets, such as the tumor margin or the metabolic hotspot. CONCLUSIONS In this study, the authors defined a specific protocol for multimodality imaging data in suspected LGGs, and they propose the application of this new protocol for advanced navigation-guided procedures optimally in conjunction with continuous electromagnetic instrument tracking to optimize glioma surgery.

Diffusion and perfusion weighted magnetic resonance imaging for tumor volume definition in radiotherapy of brain tumors.

PubMed

Guo, Lu; Wang, Gang; Feng, Yuanming; Yu, Tonggang; Guo, Yu; Bai, Xu; Ye, Zhaoxiang

2016-09-21

Accurate target volume delineation is crucial for the radiotherapy of tumors. Diffusion and perfusion magnetic resonance imaging (MRI) can provide functional information about brain tumors, and they are able to detect tumor volume and physiological changes beyond the lesions shown on conventional MRI. This review examines recent studies that utilized diffusion and perfusion MRI for tumor volume definition in radiotherapy of brain tumors, and it presents the opportunities and challenges in the integration of multimodal functional MRI into clinical practice. The results indicate that specialized and robust post-processing algorithms and tools are needed for the precise alignment of targets on the images, and comprehensive validations with more clinical data are important for the improvement of the correlation between histopathologic results and MRI parameter images.

Comparison of endorectal coil and nonendorectal coil T2W and diffusion-weighted MRI at 3 Tesla for localizing prostate cancer: correlation with whole-mount histopathology.

PubMed

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.

TH-A-BRF-05: MRI of Individual Lymph Nodes to Guide Regional Breast Radiotherapy

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

Heijst, T van; Asselen, B van; Lagendijk, J

2014-06-15

Purpose: In regional radiotherapy (RT) for breast-cancer patients, direct visualization of individual lymph nodes (LNs) may reduce target volumes and Result in lower toxicity (i.e. reduced radiation pneumonitis, arm edema, arm morbidity), relative to standard CT-based delineations. To this end, newly designed magnetic resonance imaging (MRI) sequences were optimized and assessed qualitatively and quantitatively. Methods: In ten healthy female volunteers, a scanning protocol was developed and optimized. Coronal images were acquired in supine RT position positioned on a wedge board on a 1.5 T Ingenia (Philips) wide-bore MRI. In four volunteers the optimized MRI protocol was applied, including a 3-dimensionalmore » (3D) T1-weighted (T1w) fast-field-echo (FFE). T2w sequences, including 3D FFE, 3D and 2D fast spin echo (FSE), and diffusion-weighted single-shot echo-planar imaging (DWI) were also performed. Several fatsuppression techniques were used. Qualitative evaluation parameters included LN contrast, motion susceptibility, visibility of anatomical structures, and fat suppression. The number of visible axillary and supraclavicular LNs was also determined. Results: T1 FFE, insensitive to motion, lacked contrast of LNs, which often blended in with soft tissue and blood. T2 FFE showed high contrast, but some LNs were obscured due to motion. Both 2D and 3D FSE were motion-insensitive having high contrast, although some blood remained visible. 2D FSE showed more anatomical details, while in 3D FSE, some blurring occurred. DWI showed high LN contrast, but suffered from geometric distortions and low resolution. Fat suppression by mDixon was the most reliable in regions with magnetic-field inhomogeneities. The FSE sequences showed the highest sensitivity for LN detection. Conclusion: MRI of regional LNs was achieved in volunteers. The FSE techniques were robust and the most sensitive. Our optimized MRI sequences can facilitate direct delineation of individual LNs. This can Result in smaller target volumes and reduced toxicity in regional RT compared to standard CT planning.« less

Reliability of magnetic resonance imaging for the detection of hypopituitarism in children with optic nerve hypoplasia.

PubMed

Ramakrishnaiah, Raghu H; Shelton, Julie B; Glasier, Charles M; Phillips, Paul H

2014-01-01

It is essential to identify hypopituitarism in children with optic nerve hypoplasia (ONH) because they are at risk for developmental delay, seizures, or death. The purpose of this study is to determine the reliability of neurohypophyseal abnormalities on magnetic resonance imaging (MRI) for the detection of hypopituitarism in children with ONH. Cross-sectional study. One hundred one children with clinical ONH who underwent MRI of the brain and orbits and a detailed pediatric endocrinologic evaluation. Magnetic resonance imaging studies were performed on 1.5-Tesla scanners. The imaging protocol included sagittal T1-weighted images, axial fast fluid-attenuated inversion-recovery/T2-weighted images, and diffusion-weighted images of the brain. Orbital imaging included fat-saturated axial and coronal images and high-resolution axial T2-weighted images. The MRI studies were reviewed by 2 pediatric neuroradiologists for optic nerve hypoplasia, absent or ectopic posterior pituitary, absent pituitary infundibulum, absent septum pellucidum, migration anomalies, and hemispheric injury. Medical records were reviewed for clinical examination findings and endocrinologic status. All patients underwent a clinical evaluation by a pediatric endocrinologist and a standardized panel of serologic testing that included serum insulin-like growth factor-1, insulin-like growth factor binding protein-3, prolactin, cortisol, adrenocorticotropic hormone, thyroid-stimulating hormone, and free thyroxine levels. Radiologists were masked to patients' endocrinologic status and funduscopic findings. Sensitivity and specificity of MRI findings for the detection of hypopituitarism. Neurohypophyseal abnormalities, including absent pituitary infundibulum, ectopic posterior pituitary bright spot, and absent posterior pituitary bright spot, occurred in 33 children. Magnetic resonance imaging disclosed neurohypophyseal abnormalities in 27 of the 28 children with hypopituitarism (sensitivity, 96%). A normal neurohypophysis occurred in 67 of 73 children with normal endocrinologic function (specificity, 92%). Neurohypophyseal abnormalities on MRI are sensitive and specific indicators of hypopituitarism in children with ONH. Copyright © 2014 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Diffusion kurtosis imaging of the liver at 3 Tesla: in vivo comparison to standard diffusion-weighted imaging.

PubMed

Budjan, Johannes; Sauter, Elke A; Zoellner, Frank G; Lemke, Andreas; Wambsganss, Jens; Schoenberg, Stefan O; Attenberger, Ulrike I

2018-01-01

Background Functional techniques like diffusion-weighted imaging (DWI) are gaining more and more importance in liver magnetic resonance imaging (MRI). Diffusion kurtosis imaging (DKI) is an advanced technique that might help to overcome current limitations of DWI. Purpose To evaluate DKI for the differentiation of hepatic lesions in comparison to conventional DWI at 3 Tesla. Material and Methods Fifty-six consecutive patients were examined using a routine abdominal MR protocol at 3 Tesla which included DWI with b-values of 50, 400, 800, and 1000 s/mm 2 . Apparent diffusion coefficient maps were calculated applying a standard mono-exponential fit, while a non-Gaussian kurtosis fit was used to obtain DKI maps. ADC as well as Kurtosis-corrected diffusion ( D) values were quantified by region of interest analysis and compared between lesions. Results Sixty-eight hepatic lesions (hepatocellular carcinoma [HCC] [n = 25]; hepatic adenoma [n = 4], cysts [n = 18]; hepatic hemangioma [HH] [n = 18]; and focal nodular hyperplasia [n = 3]) were identified. Differentiation of malignant and benign lesions was possible based on both DWI ADC as well as DKI D-values ( P values were in the range of 0.04 to < 0.0001). Conclusion In vivo abdominal DKI calculated using standard b-values is feasible and enables quantitative differentiation between malignant and benign liver lesions. Assessment of conventional ADC values leads to similar results when using b-values below 1000 s/mm 2 for DKI calculation.

Multiparametric Magnetic Resonance Imaging for Active Surveillance of Prostate Cancer.

PubMed

An, Julie Y; Sidana, Abhinav; Choyke, Peter L; Wood, Bradford J.; Pinto, Peter A; Türkbey, İsmail Barış

2017-09-29

Active surveillance has gained popularity as an acceptable management option for men with low-risk prostate cancer. Successful utilization of this strategy can delay or prevent unnecessary interventions - thereby reducing morbidity associated with overtreatment. The usefulness of active surveillance primarily depends on correct identification of patients with low-risk disease. However, current population-wide algorithms and tools do not adequately exclude high-risk disease, thereby limiting the confidence of clinicians and patients to go on active surveillance. Novel imaging tools such as mpMRI provide information about the size and location of potential cancers enabling more informed treatment decisions. The term "multiparametric" in prostate mpMRI refers to the summation of several MRI series into one examination whose initial goal is to identify potential clinically-significant lesions suitable for targeted biopsy. The main advantages of MRI are its superior anatomic resolution and the lack of ionizing radiation. Recently, the Prostate Imaging-Reporting and Data System has been instituted as an international standard for unifying mpMRI results. The imaging sequences in mpMRI defined by Prostate Imaging Reporting and Data System version 2 includes: T2-weighted MRI, diffusion-weighted MRI, derived apparent-diffusion coefficient from diffusion-weighted MRI, and dynamic contrast-enhanced MRI. The use of mpMRI prior to starting active surveillance could prevent those with missed, high-grade lesions from going on active surveillance, and reassure those with minimal disease who may be hesitant to take part in active surveillance. Although larger validation studies are still necessary, preliminary results suggest mpMRI has a role in selecting patients for active surveillance. Less certain is the role of mpMRI in monitoring patients on active surveillance, as data on this will take a long time to mature. The biggest obstacles to routine use of prostate MRI are quality control, cost, reproducibility, and access. Nevertheless, there is great a potential for mpMRI to improve outcomes and quality of treatment. The major roles of MRI will continue to expand and its emerging use in standard of care approaches becomes more clearly defined and supported by increasing levels of data.

Anatomic study of the canine stifle using low-field magnetic resonance imaging (MRI) and MRI arthrography.

PubMed

Pujol, Esteban; Van Bree, Henri; Cauzinille, Laurent; Poncet, Cyrill; Gielen, Ingrid; Bouvy, Bernard

2011-06-01

To investigate the use of low-field magnetic resonance imaging (MRI) and MR arthrography in normal canine stifles and to compare MRI images to gross dissection. Descriptive study. Adult canine pelvic limbs (n=17). Stifle joints from 12 dogs were examined by orthopedic and radiographic examination, synovial fluid analysis, and MRI performed using a 0.2 T system. Limbs 1 to 7 were used to develop the MR and MR arthrography imaging protocol. Limbs 8-17 were studied with the developed MR and MR arthrography protocol and by gross dissection. Three sequences were obtained: T1-weighted spin echo (SE) in sagittal, dorsal, and transverse plane; T2-weighted SE in sagittal plane and T1-gradient echo in sagittal plane. Specific bony and soft tissue structures were easily identifiable with the exception of articular cartilage. The cranial and caudal cruciate ligaments were identified. Medial and lateral menisci were seen as wedge-shaped hypointense areas. MR arthrography permitted further delineation of specific structures. MR images corresponded with gross dissection morphology. With the exception of poor delineation of articular cartilage, a low-field MRI and MR arthrography protocol provides images of adequate quality to assess the normal canine stifle joint. © Copyright 2011 by The American College of Veterinary Surgeons.

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

PubMed

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.

Diffusion-weighted magnetic resonance imaging for assessment of lung lesions: repeatability of the apparent diffusion coefficient measurement.

PubMed

Bernardin, L; Douglas, N H M; Collins, D J; Giles, S L; O'Flynn, E A M; Orton, M; deSouza, N M

2014-02-01

To establish repeatability of apparent diffusion coefficients (ADCs) acquired from free-breathing diffusion-weighted magnetic resonance imaging (DW-MRI) in malignant lung lesions and investigate effects of lesion size, location and respiratory motion. Thirty-six malignant lung lesions (eight patients) were examined twice (1- to 5-h interval) using T1-weighted, T2-weighted and axial single-shot echo-planar DW-MRI (b = 100, 500, 800 s/mm(2)) during free-breathing. Regions of interest around target lesions on computed b = 800 s/mm(2) images by two independent observers yielded ADC values from maps (pixel-by-pixel fitting using all b values and a mono-exponential decay model). Intra- and inter-observer repeatability was assessed per lesion, per patient and by lesion size (> or <2 cm) or location. ADCs were similar between observers (mean ± SD, 1.15 ± 0.28 × 10(-3) mm(2)/s, observer 1; 1.15 ± 0.29 × 10(-3) mm(2)/s, observer 2). Intra-observer coefficients of variation of the mean [median] ADC per lesion and per patient were 11% [11.4%], 5.7% [5.7%] for observer 1 and 9.2% [9.5%], 3.9% [4.7%] for observer 2 respectively; inter-observer values were 8.9% [9.3%] (per lesion) and 3.0% [3.7%] (per patient). Inter-observer coefficient of variation (CoV) was greater for lesions <2 cm (n = 20) compared with >2 cm (n = 16) (10.8% vs 6.5% ADCmean, 11.3% vs 6.7% ADCmedian) and for mid (n = 14) vs apical (n = 9) or lower zone (n = 13) lesions (13.9%, 2.7%, 3.8% respectively ADCmean; 14.2%, 2.8%, 4.7% respectively ADCmedian). Free-breathing DW-MRI of whole lung achieves good intra- and inter-observer repeatability of ADC measurements in malignant lung tumours. • Diffusion-weighted MRI of the lung can be satisfactorily acquired during free-breathing • DW-MRI demonstrates high contrast between primary and metastatic lesions and normal lung • Apparent diffusion coefficient (ADC) measurements in lung tumours are repeatable and reliable • ADC offers potential in assessing response in lung metastases in clinical trials.

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

PubMed

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 < 0.05). Malignant skull-involved lesions demonstrated a significantly lower ADC ( P = 0.016) than benign lesions. ROC curve analyses indicated that a combination of CT, MRI, and DWI with an ADC ≤ 0.703 × 10 -3 mm 2 /s showed optimal sensitivity, while DWI along showed optimal specificity of 88.4% in differentiating between 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.

Role of MRI in osteosarcoma for evaluation and prediction of chemotherapy response: correlation with histological necrosis.

PubMed

Bajpai, Jyoti; Gamnagatti, Shivanand; Kumar, Rakesh; Sreenivas, Vishnubhatla; Sharma, Mehar Chand; Khan, Shah Alam; Rastogi, Shishir; Malhotra, Arun; Safaya, Rajni; Bakhshi, Sameer

2011-04-01

Histological necrosis, the current standard for response evaluation in osteosarcoma, is attainable after neoadjuvant chemotherapy. To establish the role of surrogate markers of response prediction and evaluation using MRI in the early phases of the disease. Thirty-one treatment-naïve osteosarcoma patients received three cycles of neoadjuvant chemotherapy followed by surgery during 2006-2008. All patients underwent baseline and post-chemotherapy conventional, diffusion-weighted and dynamic contrast-enhanced MRI. Taking histological response (good response ≥90% necrosis) as the reference standard, various parameters of MRI were compared to it. A tumor was considered ellipsoidal; volume, average tumor plane and its relative value (average tumor plane relative/body surface area) was calculated using the standard formula for ellipse. Receiver operating characteristic curves were generated to assess best threshold and predictability. After deriving thresholds for each parameter in univariable analysis, multivariable analysis was carried out. Both pre-and post-chemotherapy absolute and relative-size parameters correlated well with necrosis. Apparent diffusion coefficient did not correlate with necrosis; however, on adjusting for volume, significant correlation was found. Thus, we could derive a new parameter: diffusion per unit volume. In osteosarcoma, chemotherapy response can be predicted and evaluated by conventional and diffusion-weighted MRI early in the disease course and it correlates well with necrosis. Further, newly derived parameter diffusion per unit volume appears to be a sensitive substitute for response evaluation in osteosarcoma.

Rapid resolution of diffusion weighted MRI abnormality in a patient with a stuttering stroke

PubMed Central

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

Comparison of gadolinium-EOB-DTPA-enhanced and diffusion-weighted liver MRI for detection of small hepatic metastases.

PubMed

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.

Dynamic Contrast Magnetic Resonance Imaging (DCE-MRI) and Diffusion Weighted MR Imaging (DWI) for Differentiation between Benign and Malignant Salivary Gland Tumors

PubMed Central

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 MRI (DWI) can indicate the characteristics of tumor tissue. Methods DCE-MRI analysis is based on the parameters of time intensity curve (TIC) before and after contrast agent injection. This method has the potential to identify the angiogenesis of tumors. DWI analysis is performed according to diffusion of water molecules in a tissue for determination of the cellularity of tumors. Conclusion According to the literature, these methods cannot be used individually to differentiate benign from malignant salivary gland tumors. An effective approach could be to combine the aforementioned methods to increase the accuracy of discrimination between different tumor types. The main objective of this study is to explore the application of DCE-MRI and DWI for assessment of salivary gland tumor types. PMID:26688794

Non-invasive detection of infection in acute pancreatic and acute necrotic collections with diffusion-weighted magnetic resonance imaging: preliminary findings.

PubMed

Islim, Filiz; Salik, Aysun Erbahceci; Bayramoglu, Sibel; Guven, Koray; Alis, Halil; Turhan, Ahmet Nuray

2014-06-01

The purpose of this study was to evaluate the contribution of diffusion-weighted magnetic resonance imaging (DW-MRI) to the detection of infection in acute pancreatitis-related collections. A total of 21 DW-MRI, and computed tomography (CT) were performed on 20 patients diagnosed as acute pancreatitis with acute peri-pancreatic fluid or necrotic collections. Collections were classified as infected or sterile according to the culture and follow-up results. Collections with gas bubbles on CT images were considered to be infected. Collections with peripheral bright signals on DW-MRI images were considered to be positive, whereas those without signals were considered to be negative. Apparent diffusion coefficient (ADC) values of the peripheral and central parts of the collections were measured. Student's t test was used to compare the means of ADC values of independent groups. Apart from one false positive result, the presence of infection was detected by DW-MRI with 95.2% accuracy. The sensitivity and accuracy of DW-MRI were higher than CT for the detection of infection. The ADC values in the central parts of the collections were significantly different between the infected and sterile groups. DW-MRI can be used as a non-invasive technique for the detection of infection in acute pancreatitis-associated collections.

Acute Brain Imaging in Children: Can MRI Replace CT as a Screening Tool?

PubMed

Wagner, Matthias W; Kontzialis, Marinos; Seeburg, Daniel; Stern, Steven E; Oshmyansky, Alexander; Poretti, Andrea; Huisman, Thierry A G M

2016-01-01

To determine if axial T2-weighted imaging can serve as screening tool for pediatric brain imaging. We retrospectively evaluated consecutive brain magnetic resonance imaging (MRI) data of 161 children (74 girls) with a mean age of 7.44 ± 5.71 years. Standard of reference was the final report of neuroradiology attendings. Three readers with different levels of experience were blinded for clinical diagnoses and study indications. First, readers studied only the axial T2-weighted screening sequence. Second, they studied all available anatomical and functional MRI sequences as performed per standard protocol for each clinical indication. The readings were classified as normal or abnormal. Sensitivity and specificity were measured. Axial T2 screening yielded a sensitivity of 77-88% and a specificity of 92%. The full studies/data sets had a sensitivity of 89-95% and a specificity of 86-93%. Nineteen of 167 studies were acquired for acute and 148 of 167 studies for nonacute clinical indication. Twenty-five false-negative diagnoses paneled in three groups were made by all readers together. Readers misread four of 19 studies with acute and 21 of 148 studies with nonacute clinical indication. Four of 21 misread studies with nonacute indications harbored unexpected findings needing management. Axial T2 screening can detect pediatric brain abnormalities with high sensitivity and specificity and can possibly replace CT as screening tool if the reading physician is aware of possible limitations/pitfalls. The level of experience influences sensitivity and specificity. Adding diffusion-weighted imaging and susceptibility-weighted imaging to a 3-dimensional T2-weighted sequence would most likely further increase sensitivity and specificity. Copyright © 2015 by the American Society of Neuroimaging.

Multi-modal magnetic resonance imaging in the acute and sub-acute phase of mild traumatic brain injury: can we see the difference?

PubMed

Toth, Arnold; Kovacs, Noemi; Perlaki, Gabor; Orsi, Gergely; Aradi, Mihaly; Komaromy, Hedvig; Ezer, Erzsebet; Bukovics, Peter; Farkas, Orsolya; Janszky, Jozsef; Doczi, Tamas; Buki, Andras; Schwarcz, Attila

2013-01-01

Advanced magnetic resonance imaging (MRI) methods were shown to be able to detect the subtle structural consequences of mild traumatic brain injury (mTBI). The objective of this study was to investigate the acute structural alterations and recovery after mTBI, using diffusion tensor imaging (DTI) to reveal axonal pathology, volumetric analysis, and susceptibility weighted imaging (SWI) to detect microhemorrhage. Fourteen patients with mTBI who had computed tomography with negative results underwent MRI within 3 days and 1 month after injury. High resolution T1-weighted imaging, DTI, and SWI, were performed at both time points. A control group of 14 matched volunteers were also examined following the same imaging protocol and time interval. Tract-Based Spatial Statistics (TBSS) were performed on DTI data to reveal group differences. T1-weighted images were fed into Freesurfer volumetric analysis. TBSS showed fractional anisotropy (FA) to be significantly (corrected p<0.05) lower, and mean diffusivity (MD) to be higher in the mTBI group in several white matter tracts (FA=40,737; MD=39,078 voxels) compared with controls at 72 hours after injury and still 1month later for FA. Longitudinal analysis revealed significant change (i.e., normalization) of FA and MD over 1 month dominantly in the left hemisphere (FA=3408; MD=7450 voxels). A significant (p<0.05) decrease in cortical volumes (mean 1%) and increase in ventricular volumes (mean 3.4%) appeared at 1 month after injury in the mTBI group. SWI did not reveal microhemorrhage in our patients. Our findings present dynamic micro- and macrostructural changes occurring in the acute to sub-acute phase in mTBI, in very mildly injured patients lacking microhemorrhage detectable by SWI. These results underscore the importance of strictly defined image acquisition time points when performing MRI studies on patients with mTBI.

Documenting the location of systematic transrectal ultrasound-guided prostate biopsies: correlation with multi-parametric MRI.

PubMed

Turkbey, Baris; Xu, Sheng; Kruecker, Jochen; Locklin, Julia; Pang, Yuxi; Shah, Vijay; Bernardo, Marcelino; Baccala, Angelo; Rastinehad, Ardeshir; Benjamin, Compton; Merino, Maria J; Wood, Bradford J; Choyke, Peter L; Pinto, Peter A

2011-03-29

During transrectal ultrasound (TRUS)-guided prostate biopsies, the actual location of the biopsy site is rarely documented. Here, we demonstrate the capability of TRUS-magnetic resonance imaging (MRI) image fusion to document the biopsy site and correlate biopsy results with multi-parametric MRI findings. Fifty consecutive patients (median age 61 years) with a median prostate-specific antigen (PSA) level of 5.8 ng/ml underwent 12-core TRUS-guided biopsy of the prostate. Pre-procedural T2-weighted magnetic resonance images were fused to TRUS. A disposable needle guide with miniature tracking sensors was attached to the TRUS probe to enable fusion with MRI. Real-time TRUS images during biopsy and the corresponding tracking information were recorded. Each biopsy site was superimposed onto the MRI. Each biopsy site was classified as positive or negative for cancer based on the results of each MRI sequence. Sensitivity, specificity, and receiver operating curve (ROC) area under the curve (AUC) values were calculated for multi-parametric MRI. Gleason scores for each multi-parametric MRI pattern were also evaluated. Six hundred and 5 systemic biopsy cores were analyzed in 50 patients, of whom 20 patients had 56 positive cores. MRI identified 34 of 56 positive cores. Overall, sensitivity, specificity, and ROC area values for multi-parametric MRI were 0.607, 0.727, 0.667, respectively. TRUS-MRI fusion after biopsy can be used to document the location of each biopsy site, which can then be correlated with MRI findings. Based on correlation with tracked biopsies, T2-weighted MRI and apparent diffusion coefficient maps derived from diffusion-weighted MRI are the most sensitive sequences, whereas the addition of delayed contrast enhancement MRI and three-dimensional magnetic resonance spectroscopy demonstrated higher specificity consistent with results obtained using radical prostatectomy specimens.

Joint 6D k-q Space Compressed Sensing for Accelerated High Angular Resolution Diffusion MRI.

PubMed

Cheng, Jian; Shen, Dinggang; Basser, Peter J; Yap, Pew-Thian

2015-01-01

High Angular Resolution Diffusion Imaging (HARDI) avoids the Gaussian. diffusion assumption that is inherent in Diffusion Tensor Imaging (DTI), and is capable of characterizing complex white matter micro-structure with greater precision. However, HARDI methods such as Diffusion Spectrum Imaging (DSI) typically require significantly more signal measurements than DTI, resulting in prohibitively long scanning times. One of the goals in HARDI research is therefore to improve estimation of quantities such as the Ensemble Average Propagator (EAP) and the Orientation Distribution Function (ODF) with a limited number of diffusion-weighted measurements. A popular approach to this problem, Compressed Sensing (CS), affords highly accurate signal reconstruction using significantly fewer (sub-Nyquist) data points than required traditionally. Existing approaches to CS diffusion MRI (CS-dMRI) mainly focus on applying CS in the q-space of diffusion signal measurements and fail to take into consideration information redundancy in the k-space. In this paper, we propose a framework, called 6-Dimensional Compressed Sensing diffusion MRI (6D-CS-dMRI), for reconstruction of the diffusion signal and the EAP from data sub-sampled in both 3D k-space and 3D q-space. To our knowledge, 6D-CS-dMRI is the first work that applies compressed sensing in the full 6D k-q space and reconstructs the diffusion signal in the full continuous q-space and the EAP in continuous displacement space. Experimental results on synthetic and real data demonstrate that, compared with full DSI sampling in k-q space, 6D-CS-dMRI yields excellent diffusion signal and EAP reconstruction with low root-mean-square error (RMSE) using 11 times less samples (3-fold reduction in k-space and 3.7-fold reduction in q-space).

Uterine sarcoma vs adenocarcinoma: can MRI distinguish between them?

PubMed

Hernández Mateo, P; Méndez Fernández, R; Serrano Tamayo, E

2016-01-01

To analyze the MRI characteristics of uterine sarcomas (mainly carcinosarcomas) and to compare them with those of adenocarcinomas to define the findings that would be useful for the differential diagnosis. We retrospectively reviewed the MRI studies of 13 patients with histologically diagnosed uterine sarcoma. We analyzed tumor size, signal in T2-weighted, unenhanced and gadolinium-enhanced T1-weighted, and diffusion-weighted sequences. We compared the data obtained with those of another series of 30 consecutive cases of adenocarcinomas studied with MRI. The sarcomas (> 9cm in 77% of cases) were considerably larger than the adenocarcinomas (p<0.001). There were no differences in FIGO staging by MRI or surgery: both tumor types were diagnosed in early stages. The signal intensity in T2-weighted images differed significantly between the two tumor types: all the sarcomas were heterogeneous and predominantly hyperintense with respect to the myometrium in T2-weighted sequences (p<0.001). In postcontrast studies, all the sarcomas showed enhancement greater than or equal to the myometrium; this finding was significantly different from the adenocarcinomas (p<0.001). In diffusion-weighted sequences, we found no significant differences in ADC values in the areas with greatest restriction, but the ADC map was more heterogeneous in the sarcomas. Uterine sarcomas do not have specific characteristics on MRI, but some findings can indicate the diagnosis. In our study, we found significant differences between sarcomas and adenocarcinomas. Sarcomas were larger, had more hyperintense and heterogeneous signal intensity in T2-weighted sequences, and enhanced more than or at least as much as the myometrium. Copyright © 2015 SERAM. Published by Elsevier España, S.L.U. All rights reserved.

Cerebral microbleeds, cognitive impairment, and MRI in patients with diabetes mellitus.

PubMed

Zhou, Hong; Yang, Juan; Xie, Peihan; Dong, Yulan; You, Yong; Liu, Jincai

2017-07-01

Cerebral microbleeds (CMBs), a typical imaging manifestation marker of sporadic cerebral small vessel disease, play a critical role in vascular cognitive impairment, which is often accompanied by diabetes mellitus (DM). Hence, CMBs may, in part, be responsible for the occurrence and development of cognitive impairment in patients with diabetes. Novel magnetic resonance imaging (MRI) sequences, such as susceptibility-weighted imaging and T2*-weighted gradient-echo, have the capability of noninvasively revealing CMBs in the brain. Moreover, a correlation between CMBs and cognitive impairment in patients with diabetes has been suggested in applications of functional MRI (fMRI). Since pathological changes in the brain occur prior to observable decline in cognitive function, neuroimaging may help predict the progression of cognitive impairment in diabetic patients. In this article, we review the detection of CMBs using MRI in diabetic patients exhibiting cognitive impairment. Future studies should emphasize the development and establishment of a novel MRI protocol, including fMRI, for diabetic patients with cognitive impairment to detect CMBs. A reliable MRI protocol would also be helpful in understanding the pathological mechanisms of cognitive impairment in this important patient population. Copyright © 2017. Published by Elsevier B.V.

Usefulness of diffusion-weighted MR imaging for differentiating between benign and malignant superficial soft tissue tumours and tumour-like lesions

PubMed Central

Jeon, Ji Young; Lee, Min Hee; Lee, Sang Hoon; Shin, Myung Jin

2016-01-01

Objective: To evaluate the usefulness of adding diffusion-weighted imaging (DWI) with apparent diffusion coefficient (ADC) mapping to conventional 3.0-T MRI to differentiate between benign and malignant superficial soft-tissue masses (SSTMs). Methods: The institutional review board approved this study and informed consent was waived. The authors retrospectively analyzed conventional MR images including diffusion-weighted images (b-values: 0, 400, 800 s mm−2) in 60 histologically proven SSTMs (35 benign and 25 malignant) excluding lipomas. Two radiologists independently evaluated the conventional MRI alone and again with the additional DWI for the evaluation of malignant masses. The mean ADC values measured within an entire mass and the contrast-enhancing solid portion were used for quantitative analysis. Diagnostic performances were compared using receiver-operating characteristic analysis. Results: For an inexperienced reader, using only conventional MRI, the sensitivity, specificity and accuracy were 84%, 80% and 81.6%, respectively. When combining conventional MRI and DWI, the sensitivity, specificity and accuracy were 96%, 85.7% and 90%, respectively. Additional DWI influenced the improvement of the rate of correct diagnosis by 8.3% (5/60). For an experienced reader, additional DWI revealed the same accuracy of 86.7% without added value on the correct diagnosis. The group mean ADCs of malignant SSTMs were significantly lower than that of benign SSTMs (p < 0.001). The best diagnostic performance with respect to differentiation of SSTMs could be obtained when conventional MRI was assessed in combination with DWI. Conclusion: Adding qualitative and quantitative DWI to conventional MRI can improve the diagnostic performance for the differentiation between benign and malignant SSTMs. Advances in knowledge: Because the imaging characteristics of many malignant superficial soft-tissue lesions overlap with those of benign ones, inadequate surgical resection due to misinterpretation of MRI often occurs. Adding DWI to conventional MRI yields greater diagnostic performances [area under the receiver-operating characteristic curve (AUC), 0.83–0.99] than does the use of conventional MRI alone (AUC, 0.71–0.93) in the evaluation of malignant superficial masses by inexperienced readers. PMID:26892266

Combined diffusion-weighted, blood oxygen level-dependent, and dynamic contrast-enhanced MRI for characterization and differentiation of renal cell carcinoma.

PubMed

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.

Prospective and retrospective high order eddy current mitigation for diffusion weighted echo planar imaging.

PubMed

Xu, Dan; Maier, Joseph K; King, Kevin F; Collick, Bruce D; Wu, Gaohong; Peters, Robert D; Hinks, R Scott

2013-11-01

The proposed method is aimed at reducing eddy current (EC) induced distortion in diffusion weighted echo planar imaging, without the need to perform further image coregistration between diffusion weighted and T2 images. These ECs typically have significant high order spatial components that cannot be compensated by preemphasis. High order ECs are first calibrated at the system level in a protocol independent fashion. The resulting amplitudes and time constants of high order ECs can then be used to calculate imaging protocol specific corrections. A combined prospective and retrospective approach is proposed to apply correction during data acquisition and image reconstruction. Various phantom, brain, body, and whole body diffusion weighted images with and without the proposed method are acquired. Significantly reduced image distortion and misregistration are consistently seen in images with the proposed method compared with images without. The proposed method is a powerful (e.g., effective at 48 cm field of view and 30 cm slice coverage) and flexible (e.g., compatible with other image enhancements and arbitrary scan plane) technique to correct high order ECs induced distortion and misregistration for various diffusion weighted echo planar imaging applications, without the need for further image post processing, protocol dependent prescan, or sacrifice in signal-to-noise ratio. Copyright © 2013 Wiley Periodicals, Inc.

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

NASA Astrophysics Data System (ADS)

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.

Evaluation of the specificity and sensitivity of ferritin as an MRI reporter gene in the mouse brain using lentiviral and adeno-associated viral vectors.

PubMed

Vande Velde, G; Rangarajan, J R; Toelen, J; Dresselaers, T; Ibrahimi, A; Krylychkina, O; Vreys, R; Van der Linden, A; Maes, F; Debyser, Z; Himmelreich, U; Baekelandt, V

2011-06-01

The development of in vivo imaging protocols to reliably track transplanted cells or to report on gene expression is critical for treatment monitoring in (pre)clinical cell and gene therapy protocols. Therefore, we evaluated the potential of lentiviral vectors (LVs) and adeno-associated viral vectors (AAVs) to express the magnetic resonance imaging (MRI) reporter gene ferritin in the rodent brain. First, we compared the induction of background MRI contrast for both vector systems in immune-deficient and immune-competent mice. LV injection resulted in hypointense (that is, dark) changes of T(2)/T(2)(*) (spin-spin relaxation time)-weighted MRI contrast at the injection site, which can be partially explained by an inflammatory response against the vector injection. In contrast to LVs, AAV injection resulted in reduced background contrast. Moreover, AAV-mediated ferritin overexpression resulted in significantly enhanced contrast to background on T(2)(*)-weighted MRI. Although sensitivity associated with the ferritin reporter remains modest, AAVs seem to be the most promising vector system for in vivo MRI reporter gene imaging.

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

PubMed Central

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

Symmetric Positive 4th Order Tensors & Their Estimation from Diffusion Weighted MRI⋆

PubMed Central

Barmpoutis, Angelos; Jian, Bing; Vemuri, Baba C.; Shepherd, Timothy M.

2009-01-01

In Diffusion Weighted Magnetic Resonance Image (DW-MRI) processing a 2nd order tensor has been commonly used to approximate the diffusivity function at each lattice point of the DW-MRI data. It is now well known that this 2nd-order approximation fails to approximate complex local tissue structures, such as fibers crossings. In this paper we employ a 4th order symmetric positive semi-definite (PSD) tensor approximation to represent the diffusivity function and present a novel technique to estimate these tensors from the DW-MRI data guaranteeing the PSD property. There have been several published articles in literature on higher order tensor approximations of the diffusivity function but none of them guarantee the positive semi-definite constraint, which is a fundamental constraint since negative values of the diffusivity coefficients are not meaningful. In our methods, we parameterize the 4th order tensors as a sum of squares of quadratic forms by using the so called Gram matrix method from linear algebra and its relation to the Hilbert’s theorem on ternary quartics. This parametric representation is then used in a nonlinear-least squares formulation to estimate the PSD tensors of order 4 from the data. We define a metric for the higher-order tensors and employ it for regularization across the lattice. Finally, performance of this model is depicted on synthetic data as well as real DW-MRI from an isolated rat hippocampus. PMID:17633709

Fetal lung apparent diffusion coefficient measurement using diffusion-weighted MRI at 3 Tesla: Correlation with gestational age.

PubMed

Afacan, Onur; Gholipour, Ali; Mulkern, Robert V; Barnewolt, Carol E; Estroff, Judy A; Connolly, Susan A; Parad, Richard B; Bairdain, Sigrid; Warfield, Simon K

2016-12-01

To evaluate the feasibility of using diffusion-weighted magnetic resonance imaging (DW-MRI) to assess the fetal lung apparent diffusion coefficient (ADC) at 3 Tesla (T). Seventy-one pregnant women (32 second trimester, 39 third trimester) were scanned with a twice-refocused Echo-planar diffusion-weighted imaging sequence with 6 different b-values in 3 orthogonal diffusion orientations at 3T. After each scan, a region-of-interest (ROI) mask was drawn to select a region in the fetal lung and an automated robust maximum likelihood estimation algorithm was used to compute the ADC parameter. The amount of motion in each scan was visually rated. When scans with unacceptable levels of motion were eliminated, the lung ADC values showed a strong association with gestational age (P < 0.01), increasing dramatically between 16 and 27 weeks and then achieving a plateau around 27 weeks. We show that to get reliable estimates of ADC values of fetal lungs, a multiple b-value acquisition, where motion is either corrected or considered, can be performed. J. Magn. Reson. Imaging 2016;44:1650-1655. © 2016 International Society for Magnetic Resonance in Medicine.

Condition Number as a Measure of Noise Performance of Diffusion Tensor Data Acquisition Schemes with MRI

NASA Astrophysics Data System (ADS)

Skare, Stefan; Hedehus, Maj; Moseley, Michael E.; Li, Tie-Qiang

2000-12-01

Diffusion tensor mapping with MRI can noninvasively track neural connectivity and has great potential for neural scientific research and clinical applications. For each diffusion tensor imaging (DTI) data acquisition scheme, the diffusion tensor is related to the measured apparent diffusion coefficients (ADC) by a transformation matrix. With theoretical analysis we demonstrate that the noise performance of a DTI scheme is dependent on the condition number of the transformation matrix. To test the theoretical framework, we compared the noise performances of different DTI schemes using Monte-Carlo computer simulations and experimental DTI measurements. Both the simulation and the experimental results confirmed that the noise performances of different DTI schemes are significantly correlated with the condition number of the associated transformation matrices. We therefore applied numerical algorithms to optimize a DTI scheme by minimizing the condition number, hence improving the robustness to experimental noise. In the determination of anisotropic diffusion tensors with different orientations, MRI data acquisitions using a single optimum b value based on the mean diffusivity can produce ADC maps with regional differences in noise level. This will give rise to rotational variances of eigenvalues and anisotropy when diffusion tensor mapping is performed using a DTI scheme with a limited number of diffusion-weighting gradient directions. To reduce this type of artifact, a DTI scheme with not only a small condition number but also a large number of evenly distributed diffusion-weighting gradients in 3D is preferable.

Perspectives on Porous Media MR in Clinical MRI

NASA Astrophysics Data System (ADS)

Sigmund, E. E.

2011-03-01

Many goals and challenges of research in natural or synthetic porous media are mirrored in quantitative medical MRI. This review will describe examples where MR techniques used in porous media (particularly diffusion-weighted imaging (DWI)) are applied to physiological pathologies. Tissue microstructure is one area with great overlap with porous media science. Diffusion-weighting (esp. in neurological tissue) has motivated models with explicit physical dimensions, statistical parameters, empirical descriptors, or hybrids thereof. Another clinically relevant microscopic process is active flow. Renal (kidney) tissue possesses significant active vascular / tubular transport that manifests as "pseudodiffusion." Cancerous lesions involve anomalies in both structure and flow. The tools of magnetic resonance and their interpretation in porous media has had great impact on clinical MRI, and continued cross-fertilization of ideas can only enhance the progress of both fields.

Whole-body diffusion-weighted MR image stitching and alignment to anatomical MRI

NASA Astrophysics Data System (ADS)

Ceranka, Jakub; Polfliet, Mathias; Lecouvet, Frederic; Michoux, Nicolas; Vandemeulebroucke, Jef

2017-02-01

Whole-body diffusion-weighted (WB-DW) MRI in combination with anatomical MRI has shown a great poten- tial in bone and soft tissue tumour detection, evaluation of lymph nodes and treatment response assessment. Because of the vast body coverage, whole-body MRI is acquired in separate stations, which are subsequently combined into a whole-body image. However, inter-station and inter-modality image misalignments can occur due to image distortions and patient motion during acquisition, which may lead to inaccurate representations of patient anatomy and hinder visual assessment. Automated and accurate whole-body image formation and alignment of the multi-modal MRI images is therefore crucial. We investigated several registration approaches for the formation or stitching of the whole-body image stations, followed by a deformable alignment of the multi- modal whole-body images. We compared a pairwise approach, where diffusion-weighted (DW) image stations were sequentially aligned to a reference station (pelvis), to a groupwise approach, where all stations were simultaneously mapped to a common reference space while minimizing the overall transformation. For each, a choice of input images and corresponding metrics was investigated. Performance was evaluated by assessing the quality of the obtained whole-body images, and by verifying the accuracy of the alignment with whole-body anatomical sequences. The groupwise registration approach provided the best compromise between the formation of WB- DW images and multi-modal alignment. The fully automated method was found to be robust, making its use in the clinic feasible.

The diffusion tensor imaging (DTI) component of the NIH MRI study of normal brain development (PedsDTI).

PubMed

Walker, Lindsay; Chang, Lin-Ching; Nayak, Amritha; Irfanoglu, M Okan; Botteron, Kelly N; McCracken, James; McKinstry, Robert C; Rivkin, Michael J; Wang, Dah-Jyuu; Rumsey, Judith; Pierpaoli, Carlo

2016-01-01

The NIH MRI Study of normal brain development sought to characterize typical brain development in a population of infants, toddlers, children and adolescents/young adults, covering the socio-economic and ethnic diversity of the population of the United States. The study began in 1999 with data collection commencing in 2001 and concluding in 2007. The study was designed with the final goal of providing a controlled-access database; open to qualified researchers and clinicians, which could serve as a powerful tool for elucidating typical brain development and identifying deviations associated with brain-based disorders and diseases, and as a resource for developing computational methods and image processing tools. This paper focuses on the DTI component of the NIH MRI study of normal brain development. In this work, we describe the DTI data acquisition protocols, data processing steps, quality assessment procedures, and data included in the database, along with database access requirements. For more details, visit http://www.pediatricmri.nih.gov. This longitudinal DTI dataset includes raw and processed diffusion data from 498 low resolution (3 mm) DTI datasets from 274 unique subjects, and 193 high resolution (2.5 mm) DTI datasets from 152 unique subjects. Subjects range in age from 10 days (from date of birth) through 22 years. Additionally, a set of age-specific DTI templates are included. This forms one component of the larger NIH MRI study of normal brain development which also includes T1-, T2-, proton density-weighted, and proton magnetic resonance spectroscopy (MRS) imaging data, and demographic, clinical and behavioral data. Published by Elsevier Inc.

Various diffusion magnetic resonance imaging techniques for pancreatic cancer

PubMed Central

Tang, Meng-Yue; Zhang, Xiao-Ming; Chen, Tian-Wu; Huang, Xiao-Hua

2015-01-01

Pancreatic cancer is one of the most common malignant tumors and remains a treatment-refractory cancer with a poor prognosis. Currently, the diagnosis of pancreatic neoplasm depends mainly on imaging and which methods are conducive to detecting small lesions. Compared to the other techniques, magnetic resonance imaging (MRI) has irreplaceable advantages and can provide valuable information unattainable with other noninvasive or minimally invasive imaging techniques. Advances in MR hardware and pulse sequence design have particularly improved the quality and robustness of MRI of the pancreas. Diffusion MR imaging serves as one of the common functional MRI techniques and is the only technique that can be used to reflect the diffusion movement of water molecules in vivo. It is generally known that diffusion properties depend on the characterization of intrinsic features of tissue microdynamics and microstructure. With the improvement of the diffusion models, diffusion MR imaging techniques are increasingly varied, from the simplest and most commonly used technique to the more complex. In this review, the various diffusion MRI techniques for pancreatic cancer are discussed, including conventional diffusion weighted imaging (DWI), multi-b DWI based on intra-voxel incoherent motion theory, diffusion tensor imaging and diffusion kurtosis imaging. The principles, main parameters, advantages and limitations of these techniques, as well as future directions for pancreatic diffusion imaging are also discussed. PMID:26753059

Spot Sign in Acute Intracerebral Hemorrhage in Dynamic T1-Weighted Magnetic Resonance Imaging.

PubMed

Schindlbeck, Katharina A; Santaella, Anna; Galinovic, Ivana; Krause, Thomas; Rocco, Andrea; Nolte, Christian H; Villringer, Kersten; Fiebach, Jochen B

2016-02-01

In computed tomographic imaging of acute intracerebral hemorrhage spot sign on computed tomographic angiography has been established as a marker for hematoma expansion and poor clinical outcome. Although, magnetic resonance imaging (MRI) can accurately visualize acute intracerebral hemorrhage, a corresponding MRI marker is lacking to date. We prospectively examined 50 consecutive patients with acute intracerebral hemorrhage within 24 hours of symptom onset. The MRI protocol consisted of a standard stroke protocol and dynamic contrast-enhanced T1-weighted imaging with a time resolution of 7.07 s/batch. Stroke scores were assessed at admission and at time of discharge. Volume measurements of hematoma size and spot sign were performed with MRIcron. Contrast extravasation within sites of the hemorrhage (MRI spot sign) was seen in 46% of the patients. Patients with an MRI spot sign had a significantly shorter time to imaging than those without (P<0.001). The clinical outcome measured by the modified Rankin Scale was significantly worse in patients with spot sign compared with those without (P≤0.001). Hematoma expansion was observed in the spot sign group compared with the nonspot sign group, although the differences were not significant. Spot sign can be detected using MRI on postcontrast T1-weighted and dynamic T1-weighted images. It is associated with worse clinical outcome. The time course of contrast extravasation in dynamic T1 images indicates that these spots represent ongoing bleeding. © 2015 American Heart Association, Inc.

[Optimization of diagnosis indicator selection and inspection plan by 3.0T MRI in breast cancer].

PubMed

Jiang, Zhongbiao; Wang, Yunhua; He, Zhong; Zhang, Lejun; Zheng, Kai

2013-08-01

To optimize 3.0T MRI diagnosis indicator in breast cancer and to select the best MRI scan program. Totally 45 patients with breast cancers were collected, and another 35 patients with benign breast tumor served as the control group. All patients underwent 3.0T MRI, including T1- weighted imaging (T1WI), fat suppression of the T2-weighted imaging (T2WI), diffusion weighted imaging (DWI), 1H magnetic resonance spectroscopy (1H-MRS) and dynamic contrast enhanced (DCE) sequence. With operation pathology results as the gold standard in the diagnosis of breast diseases, the pathological results of benign and malignant served as dependent variables, and the diagnostic indicators of MRI were taken as independent variables. We put all the indicators of MRI examination under Logistic regression analysis, established the Logistic model, and optimized the diagnosis indicators of MRI examination to further improve MRI scan of breast cancer. By Logistic regression analysis, some indicators were selected in the equation, including the edge feature of the tumor, the time-signal intensity curve (TIC) type and the apparent diffusion coefficient (ADC) value when b=500 s/mm2. The regression equation was Logit (P)=-21.936+20.478X6+3.267X7+ 21.488X3. Valuable indicators in the diagnosis of breast cancer are the edge feature of the tumor, the TIC type and the ADC value when b=500 s/mm2. Combining conventional MRI scan, DWI and dynamic enhanced MRI is a better examination program, while MRS is the complementary program when diagnosis is difficult.

Utility of Clinical Parameters and Multiparametric MRI as Predictive Factors for Differentiating Uterine Sarcoma From Atypical Leiomyoma.

PubMed

Bi, Qiu; Xiao, Zhibo; Lv, Fajin; Liu, Yao; Zou, Chunxia; Shen, Yiqing

2018-02-05

The objective of this study was to find clinical parameters and qualitative and quantitative magnetic resonance imaging (MRI) features for differentiating uterine sarcoma from atypical leiomyoma (ALM) preoperatively and to calculate predictive values for uterine sarcoma. Data from 60 patients with uterine sarcoma and 88 patients with ALM confirmed by surgery and pathology were collected. Clinical parameters, qualitative MRI features, diffusion-weighted imaging with apparent diffusion coefficient values, and quantitative parameters of dynamic contrast-enhanced MRI of these two tumor types were compared. Predictive values for uterine sarcoma were calculated using multivariable logistic regression. Patient clinical manifestations, tumor locations, margins, T2-weighted imaging signals, mean apparent diffusion coefficient values, minimum apparent diffusion coefficient values, and time-signal intensity curves of solid tumor components were obvious significant parameters for distinguishing between uterine sarcoma and ALM (all P <.001). Abnormal vaginal bleeding, tumors located mainly in the uterine cavity, ill-defined tumor margins, and mean apparent diffusion coefficient values of <1.272 × 10 -3  mm 2 /s were significant preoperative predictors of uterine sarcoma. When the overall scores of these four predictors were greater than or equal to 7 points, the sensitivity, the specificity, the accuracy, and the positive and negative predictive values were 88.9%, 99.9%, 95.7%, 97.0%, and 95.1%, respectively. The use of clinical parameters and multiparametric MRI as predictive factors was beneficial for diagnosing uterine sarcoma preoperatively. These findings could be helpful for guiding treatment decisions. Copyright © 2018 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.

q-Space Deep Learning: Twelve-Fold Shorter and Model-Free Diffusion MRI Scans.

PubMed

Golkov, Vladimir; Dosovitskiy, Alexey; Sperl, Jonathan I; Menzel, Marion I; Czisch, Michael; Samann, Philipp; Brox, Thomas; Cremers, Daniel

2016-05-01

Numerous scientific fields rely on elaborate but partly suboptimal data processing pipelines. An example is diffusion magnetic resonance imaging (diffusion MRI), a non-invasive microstructure assessment method with a prominent application in neuroimaging. Advanced diffusion models providing accurate microstructural characterization so far have required long acquisition times and thus have been inapplicable for children and adults who are uncooperative, uncomfortable, or unwell. We show that the long scan time requirements are mainly due to disadvantages of classical data processing. We demonstrate how deep learning, a group of algorithms based on recent advances in the field of artificial neural networks, can be applied to reduce diffusion MRI data processing to a single optimized step. This modification allows obtaining scalar measures from advanced models at twelve-fold reduced scan time and detecting abnormalities without using diffusion models. We set a new state of the art by estimating diffusion kurtosis measures from only 12 data points and neurite orientation dispersion and density measures from only 8 data points. This allows unprecedentedly fast and robust protocols facilitating clinical routine and demonstrates how classical data processing can be streamlined by means of deep learning.

Magnetic resonance imaging in active surveillance—a modern approach

PubMed Central

Moore, Caroline M.

2018-01-01

In recent years, active surveillance has been increasingly adopted as a conservative management approach to low and sometimes intermediate risk prostate cancer, to avoid or delay treatment until there is evidence of higher risk disease. A number of studies have investigated the role of multiparametric magnetic resonance imaging (mpMRI) in this setting. MpMRI refers to the use of multiple MRI sequences (T2-weighted anatomical and functional imaging which can include diffusion-weighted imaging, dynamic contrast enhanced imaging, spectroscopy). Each of the parameters investigates different aspects of the prostate gland (anatomy, cellularity, vascularity, etc.). In addition to a qualitative assessment, the radiologist can also extrapolate quantitative imaging biomarkers from these sequences, for example the apparent diffusion coefficient from diffusion-weighted imaging. There are many different types of articles (e.g., reviews, commentaries, consensus meetings, etc.) that address the use of mpMRI in men on active surveillance for prostate cancer. In this paper, we compare original articles that investigate the role of the different mpMRI sequences in men on active surveillance for prostate cancer, in order to discuss the relative utility of the different sequences, and combinations of sequences. We searched MEDLINE/PubMed for manuscripts published from inception to 1st December 2017. The search terms used were (prostate cancer or prostate adenocarcinoma or prostatic carcinoma or prostate carcinoma or prostatic adenocarcinoma) and (MRI or NMR or magnetic resonance imaging or mpMRI or multiparametric MRI) and active surveillance. Overall, 425 publications were found. All abstracts were reviewed to identify papers with original data. Twenty-five papers were analysed and summarised. Some papers based their analysis only on one mpMRI sequence, while others assessed two or more. The evidence from this review suggests that qualitative assessments and quantitative data from different mpMRI sequences hold promise in the management of men on active surveillance for prostate cancer. Both qualitative and quantitative approaches should be considered when assessing mpMRI of the prostate. There is a need for robust studies assessing the relative utility of different combinations of sequences in a systematic manner to determine the most efficient use of mpMRI in men on active surveillance. PMID:29594026

Use of diffusion-weighted MRI to modify radiosurgery planning in brain metastases may reduce local recurrence.

PubMed

Zakaria, Rasheed; Pomschar, Andreas; Jenkinson, Michael D; Tonn, Jörg-Christian; Belka, Claus; Ertl-Wagner, Birgit; Niyazi, Maximilian

2017-02-01

Stereotactic radiosurgery (SRS) is an effective and well tolerated treatment for selected brain metastases; however, local recurrence still occurs. We investigated the use of diffusion weighted MRI (DWI) as an adjunct for SRS treatment planning in brain metastases. Seventeen consecutive patients undergoing complete surgical resection of a solitary brain metastasis underwent image analysis retrospectively. SRS treatment plans were generated based on standard 3D post-contrast T1-weighted sequences at 1.5T and then separately using apparent diffusion coefficient (ADC) maps in a blinded fashion. Control scans immediately post operation confirmed complete tumour resection. Treatment plans were compared to one another and with volume of local recurrence at progression quantitatively and qualitatively by calculating the conformity index (CI), the overlapping volume as a proportion of the total combined volume, where 1 = identical plans and 0 = no conformation whatsoever. Gross tumour volumes (GTVs) using ADC and post-contrast T1-weighted sequences were quantitatively the same (related samples Wilcoxon signed rank test = -0.45, p = 0.653) but showed differing conformations (CI 0.53, p < 0.001). The diffusion treatment volume (DTV) obtained by combining the two target volumes was significantly greater than the treatment volume based on post contrast T1-weighted MRI alone, both quantitatively (median 13.65 vs. 9.52 cm 3 , related samples Wilcoxon signed rank test p < 0.001) and qualitatively (CI 0.74, p = 0.001). This DTV covered a greater volume of subsequent tumour recurrence than the standard plan (median 3.53 cm 3 vs. 3.84 cm 3 , p = 0.002). ADC maps may be a useful tool in addition to the standard post-contrast T1-weighted sequence used for SRS planning.

Whole-body MRI including diffusion-weighted MRI compared with 5-HTP PET/CT in the detection of neuroendocrine tumors

PubMed Central

Carlbom, Lina; Caballero-Corbalán, José; Granberg, Dan; Sörensen, Jens; Eriksson, Barbro; Ahlström, Håkan

2017-01-01

Aim We wanted to explore if whole-body magnetic resonance imaging (MRI) including diffusion-weighted (DW) and liver-specific contrast agent-enhanced imaging could be valuable in lesion detection of neuroendocrine tumors (NET). [11C]-5-Hydroxytryptophan positron emission tomography/computed tomography (5-HTP PET/CT) was used for comparison. Materials and methods Twenty-one patients with NET were investigated with whole-body MRI, including DW imaging (DWI) and contrast-enhanced imaging of the liver, and whole-body 5-HTP PET/CT. Seven additional patients underwent upper abdomen MRI including DWI, liver-specific contrast agent-enhanced imaging, and 5-HTP PET/CT. Results There was a patient-based concordance of 61% and a lesion-based concordance of 53% between the modalities. MRI showed good concordance with PET in detecting bone metastases but was less sensitive in detecting metastases in mediastinal lymph nodes. MRI detected more liver metastases than 5-HTP PET/CT. Conclusion Whole-body MRI with DWI did not detect all NET lesions found with whole-body 5-HTP PET/CT. Our findings indicate that MRI of the liver including liver-specific contrast agent-enhanced imaging and DWI could be a useful complement to whole-body 5-HTP PET/CT. PMID:27894208

Distortion correction for diffusion-weighted MRI tractography and fMRI in the temporal lobes.

PubMed

Embleton, Karl V; Haroon, Hamied A; Morris, David M; Ralph, Matthew A Lambon; Parker, Geoff J M

2010-10-01

Single shot echo-planar imaging (EPI) sequences are currently the most commonly used sequences for diffusion-weighted imaging (DWI) and functional magnetic resonance imaging (fMRI) as they allow relatively high signal to noise with rapid acquisition time. A major drawback of EPI is the substantial geometric distortion and signal loss that can occur due to magnetic field inhomogeneities close to air-tissue boundaries. If DWI-based tractography and fMRI are to be applied to these regions, then the distortions must be accurately corrected to achieve meaningful results. We describe robust acquisition and processing methods for correcting such distortions in spin echo (SE) EPI using a variant of the reversed direction k space traversal method with a number of novel additions. We demonstrate that dual direction k space traversal with maintained diffusion-encoding gradient strength and direction results in correction of the great majority of eddy current-associated distortions in DWI, in addition to those created by variations in magnetic susceptibility. We also provide examples to demonstrate that the presence of severe distortions cannot be ignored if meaningful tractography results are desired. The distortion correction routine was applied to SE-EPI fMRI acquisitions and allowed detection of activation in the temporal lobe that had been previously found using PET but not conventional fMRI. © 2010 Wiley-Liss, Inc.

The role of magnetic resonance diffusion-weighted imaging and three-dimensional arterial spin labelling perfusion imaging in the differentiation of parasellar meningioma and cavernous haemangioma.

PubMed

Xiao, Hua-Feng; Lou, Xin; Liu, Meng-Yu; Wang, Yu-Lin; Wang, Yan; Chen, Zhi-Ye; Shi, Kai-Ning; Ma, Lin

2014-08-01

To evaluate the diagnostic value of magnetic resonance diffusion-weighted imaging (DWI) and three-dimensional arterial spin labelling perfusion imaging (3D-ASL) in distinguishing cavernous haemangioma from parasellar meningioma, using histological data as a reference standard. Patients with parasellar meningioma or parasellar cavernous haemangioma underwent conventional T1- and T2-weighted magnetic resonance imaging (MRI) followed by DWI and 3D-ASL using a 3.0 Tesla MRI. The minimum apparent diffusion coefficient (minADC) from DWI and the maximal normalized cerebral blood flow (nCBF) from 3D-ASL were measured in each tumour. Diagnosis was confirmed by histology. MinADC was significantly lower and nCBF significantly higher in meningioma (n = 19) than cavernous haemangioma (n = 15). There was a significant negative correlation between minADC and nCBF (r = -0.605). DWI and 3D-ASL are useful in differentiating cavernous haemangiomas from parasellar meningiomas, particularly in situations when the appearance on conventional MRI sequences is otherwise ambiguous. © The Author(s) 2014 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.

Is contrast enhancement needed for diagnostic prostate MRI?

PubMed Central

Rondoni, Valeria; Aisa, Maria Cristina; Martorana, Eugenio; D’Andrea, Alfredo; Malaspina, Corrado Maria; Orlandi, Agostino; Galassi, Giorgio; Orlandi, Emanuele; Scialpi, Pietro; Dragone, Michele; Palladino, Diego; Simeone, Annalisa; Amenta, Michele; Bianchi, Giampaolo

2017-01-01

Prostate Imaging Reporting and Data System version 2 (PI-RADS v2) provides clinical guidelines for multiparametric magnetic resonance imaging (mpMRI) [T2-weighted imaging (T2WI), diffusion-weighted imaging (DWI) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI)] of prostate. However, DCE-MRI seems to show a limited contribution in prostate cancer (PCa) detection and management. In our experience, DCE-MRI, did not show significant change in diagnostic performance in addition to DWI and T2WI [biparametric MRI (bpMRI)] which represent the predominant sequences to detect suspected lesions in peripheral and transitional zone (TZ). In this article we reviewed the role of DCE-MRI also indicating the potential contribute of bpMRI approach (T2WI and DWI) and lesion volume evaluation in the diagnosis and management of suspected PCa. PMID:28725592

Is contrast enhancement needed for diagnostic prostate MRI?

PubMed

Scialpi, Michele; Rondoni, Valeria; Aisa, Maria Cristina; Martorana, Eugenio; D'Andrea, Alfredo; Malaspina, Corrado Maria; Orlandi, Agostino; Galassi, Giorgio; Orlandi, Emanuele; Scialpi, Pietro; Dragone, Michele; Palladino, Diego; Simeone, Annalisa; Amenta, Michele; Bianchi, Giampaolo

2017-06-01

Prostate Imaging Reporting and Data System version 2 (PI-RADS v2) provides clinical guidelines for multiparametric magnetic resonance imaging (mpMRI) [T2-weighted imaging (T2WI), diffusion-weighted imaging (DWI) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI)] of prostate. However, DCE-MRI seems to show a limited contribution in prostate cancer (PCa) detection and management. In our experience, DCE-MRI, did not show significant change in diagnostic performance in addition to DWI and T2WI [biparametric MRI (bpMRI)] which represent the predominant sequences to detect suspected lesions in peripheral and transitional zone (TZ). In this article we reviewed the role of DCE-MRI also indicating the potential contribute of bpMRI approach (T2WI and DWI) and lesion volume evaluation in the diagnosis and management of suspected PCa.

Gene interference regulates aquaporin-4 expression in swollen tissue of rats with cerebral ischemic edema: Correlation with variation in apparent diffusion coefficient.

PubMed

Hu, Hui; Lu, Hong; He, Zhanping; Han, Xiangjun; Chen, Jing; Tu, Rong

2012-07-25

To investigate the effects of mRNA interference on aquaporin-4 expression in swollen tissue of rats with ischemic cerebral edema, and diagnose the significance of diffusion-weighted MRI, we injected 5 μL shRNA- aquaporin-4 (control group) or siRNA- aquaporin-4 solution (1:800) (RNA interference group) into the rat right basal ganglia immediately before occlusion of the middle cerebral artery. At 0.25 hours after occlusion of the middle cerebral artery, diffusion-weighted MRI displayed a high signal; within 2 hours, the relative apparent diffusion coefficient decreased markedly, aquaporin-4 expression increased rapidly, and intracellular edema was obviously aggravated; at 4 and 6 hours, the relative apparent diffusion coefficient slowly returned to control levels, aquaporin-4 expression slightly increased, and angioedema was observed. In the RNA interference group, during 0.25-6 hours after injection of siRNA- aquaporin-4 solution, the relative apparent diffusion coefficient slightly fluctuated and aquaporin-4 expression was upregulated; during 0.5-4 hours, the relative apparent diffusion coefficient was significantly higher, while aquaporin-4 expression was significantly lower when compared with the control group, and intracellular edema was markedly reduced; at 0.25 and 6 hours, the relative apparent diffusion coefficient and aquaporin-4 expression were similar when compared with the control group; obvious angioedema remained at 6 hours. Pearson's correlation test results showed that aquaporin-4 expression was negatively correlated with the apparent diffusion coefficient (r = -0.806, P < 0.01). These findings suggest that upregulated aquaporin-4 expression is likely to be the main molecular mechanism of intracellular edema and may be the molecular basis for decreased relative apparent diffusion coefficient. Aquaporin-4 gene interference can effectively inhibit the upregulation of aquaporin-4 expression during the stage of intracellular edema with time-effectiveness. Moreover, diffusion-weighted MRI can accurately detect intracellular edema.

Multiparametric Breast MRI of Breast Cancer

PubMed Central

Rahbar, Habib; Partridge, Savannah C.

2015-01-01

Synopsis Breast MRI has increased in popularity over the past two decades due to evidence for its high sensitivity for cancer detection. Current clinical MRI approaches rely on the use of a dynamic contrast enhanced (DCE-MRI) acquisition that facilitates morphologic and semi-quantitative kinetic assessments of breast lesions. The use of more functional and quantitative parameters, such as pharmacokinetic features from high temporal resolution DCE-MRI, apparent diffusion coefficient (ADC) and intravoxel incoherent motion (IVIM) on diffusion weighted MRI, and choline concentrations on MR spectroscopy, hold promise to broaden the utility of MRI and improve its specificity. However, due to wide variations in approach among centers for measuring these parameters and the considerable technical challenges, robust multicenter data supporting their routine use is not yet available, limiting current applications of many of these tools to research purposes. PMID:26613883

T2-weighted MRI-derived textural features reflect prostate cancer aggressiveness: preliminary results.

PubMed

Nketiah, Gabriel; Elschot, Mattijs; Kim, Eugene; Teruel, Jose R; Scheenen, Tom W; Bathen, Tone F; Selnæs, Kirsten M

2017-07-01

To evaluate the diagnostic relevance of T2-weighted (T2W) MRI-derived textural features relative to quantitative physiological parameters derived from diffusion-weighted (DW) and dynamic contrast-enhanced (DCE) MRI in Gleason score (GS) 3+4 and 4+3 prostate cancers. 3T multiparametric-MRI was performed on 23 prostate cancer patients prior to prostatectomy. Textural features [angular second moment (ASM), contrast, correlation, entropy], apparent diffusion coefficient (ADC), and DCE pharmacokinetic parameters (K trans and V e ) were calculated from index tumours delineated on the T2W, DW, and DCE images, respectively. The association between the textural features and prostatectomy GS and the MRI-derived parameters, and the utility of the parameters in differentiating between GS 3+4 and 4+3 prostate cancers were assessed statistically. ASM and entropy correlated significantly (p < 0.05) with both GS and median ADC. Contrast correlated moderately with median ADC. The textural features correlated insignificantly with K trans and V e . GS 4+3 cancers had significantly lower ASM and higher entropy than 3+4 cancers, but insignificant differences in median ADC, K trans , and V e . The combined texture-MRI parameters yielded higher classification accuracy (91%) than the individual parameter sets. T2W MRI-derived textural features could serve as potential diagnostic markers, sensitive to the pathological differences in prostate cancers. • T2W MRI-derived textural features correlate significantly with Gleason score and ADC. • T2W MRI-derived textural features differentiate Gleason score 3+4 from 4+3 cancers. • T2W image textural features could augment tumour characterization.

Magnetic Resonance Imaging in Patients With Mechanical Low Back Pain Using a Novel Rapid-Acquisition Three-Dimensional SPACE Sequence at 1.5-T: A Pilot Study Comparing Lumbar Stenosis Assessment With Routine Two-Dimensional Magnetic Resonance Sequences.

PubMed

Swami, Vimarsha G; Katlariwala, Mihir; Dhillon, Sukhvinder; Jibri, Zaid; Jaremko, Jacob L

2016-11-01

To minimize the burden of overutilisation of lumbar spine magnetic resonance imaging (MRI) on a resource-constrained public healthcare system, it may be helpful to image some patients with mechanical low-back pain (LBP) using a simplified rapid MRI screening protocol at 1.5-T. A rapid-acquisition 3-dimensional (3D) SPACE (Sampling Perfection with Application-optimized Contrasts using different flip angle Evolution) sequence can demonstrate common etiologies of LBP. We compared lumbar spinal canal stenosis (LSCS) and neural foraminal stenosis (LNFS) assessment on 3D SPACE against conventional 2-dimensional (2D) MRI. We prospectively performed 3D SPACE and 2D spin-echo MRI sequences (axial or sagittal T1-weighted or T2-weighted) at 1.5-T in 20 patients. Two blinded readers assessed levels L3-4, L4-5 and L5-S1 using: 1) morphologic grading systems, 2) global impression on the presence or absence of clinically significant stenosis (n = 60 disc levels for LSCS, n = 120 foramina for LNFS). Reliability statistics were calculated. Acquisition time was ∼5 minutes for SPACE and ∼20 minutes for 2D MRI sequences. Interobserver agreement of LSCS was substantial to near perfect on both sequences (morphologic grading: kappa [k] = 0.71 SPACE, k = 0.69 T2-weighted; global impression: k = 0.85 SPACE, k = 0.78 T2-weighted). LNFS assessment had superior interobserver reliability using SPACE than T1-weighted (k = 0.54 vs 0.37). Intersequence agreement of findings between SPACE and 2D MRI was substantial to near perfect by global impression (LSCS: k = 0.78 Reader 1, k = 0.85 Reader 2; LNFS: k = 0.63 Reader 1, k = 0.66 Reader 2). 3D SPACE was acquired in one-quarter the time as the conventional 2D MRI protocol, had excellent agreement with 2D MRI for stenosis assessment, and had interobserver reliability superior to 2D MRI. These results justify future work to explore the role of 3D SPACE in a rapid MRI screening protocol at 1.5-T for mechanical LBP. Copyright © 2016 Canadian Association of Radiologists. Published by Elsevier Inc. All rights reserved.

[Cavernous sinus thrombosis as a rare cause of exophthalmos in childhood : A case report].

PubMed

Kamawal, A; Schmidt, M A; Rompel, O; Gusek-Schneider, G C; Mardin, C Y; Trollmann, R

2017-05-01

Complications of acute bacterial sinusitis mostly occur in children and adolescents. In particular, intracranial spread of the infection can lead to severe even fatal courses of the disease. This article is a case report about a 13-year-old boy suffering from left-sided headache, meningismus and exophthalmos as presenting symptoms. Cranial magnetic resonance imaging (MRI) showed merely right-sided sphenoid sinusitis; however, the diffusion-weighted MRI sequence indicated a left-sided cavernous sinus thrombosis, which could be confirmed by computed tomography (CT) angiography. Cerebrospinal fluid diagnostics showed significant leukocytosis confirming secondary meningitis. Finally, exophthalmos was explained by parainfectious cavernous sinus thrombosis and periorbital edema. This case report highlights the importance of extended and specific diagnostic imaging in cases of clinically suspected complications in children and adolescents with sinusitis and the diagnostic significance of diffusion-weighted MRI.

Microstructural imaging of the human brain with a 'super-scanner': 10 key advantages of ultra-strong gradients for diffusion MRI.

PubMed

Jones, D K; Alexander, D C; Bowtell, R; Cercignani, M; Dell'Acqua, F; McHugh, D J; Miller, K L; Palombo, M; Parker, G J M; Rudrapatna, U S; Tax, C M W

2018-05-22

The key component of a microstructural diffusion MRI 'super-scanner' is a dedicated high-strength gradient system that enables stronger diffusion weightings per unit time compared to conventional gradient designs. This can, in turn, drastically shorten the time needed for diffusion encoding, increase the signal-to-noise ratio, and facilitate measurements at shorter diffusion times. This review, written from the perspective of the UK National Facility for In Vivo MR Imaging of Human Tissue Microstructure, an initiative to establish a shared 300 mT/m-gradient facility amongst the microstructural imaging community, describes ten advantages of ultra-strong gradients for microstructural imaging. Specifically, we will discuss how the increase of the accessible measurement space compared to a lower-gradient systems (in terms of Δ, b-value, and TE) can accelerate developments in the areas of 1) axon diameter distribution mapping; 2) microstructural parameter estimation; 3) mapping micro-vs macroscopic anisotropy features with gradient waveforms beyond a single pair of pulsed-gradients; 4) multi-contrast experiments, e.g. diffusion-relaxometry; 5) tractography and high-resolution imaging in vivo and 6) post mortem; 7) diffusion-weighted spectroscopy of metabolites other than water; 8) tumour characterisation; 9) functional diffusion MRI; and 10) quality enhancement of images acquired on lower-gradient systems. We finally discuss practical barriers in the use of ultra-strong gradients, and provide an outlook on the next generation of 'super-scanners'. Copyright © 2018. Published by Elsevier Inc.

The Potential for an Enhanced Role for MRI in Radiation-therapy Treatment Planning

PubMed Central

Metcalfe, P.; Liney, G. P.; Holloway, L.; Walker, A.; Barton, M.; Delaney, G. P.; Vinod, S.; Tomé, W.

2013-01-01

The exquisite soft-tissue contrast of magnetic resonance imaging (MRI) has meant that the technique is having an increasing role in contouring the gross tumor volume (GTV) and organs at risk (OAR) in radiation therapy treatment planning systems (TPS). MRI-planning scans from diagnostic MRI scanners are currently incorporated into the planning process by being registered to CT data. The soft-tissue data from the MRI provides target outline guidance and the CT provides a solid geometric and electron density map for accurate dose calculation on the TPS computer. There is increasing interest in MRI machine placement in radiotherapy clinics as an adjunct to CT simulators. Most vendors now offer 70 cm bores with flat couch inserts and specialised RF coil designs. We would refer to these devices as MR-simulators. There is also research into the future application of MR-simulators independent of CT and as in-room image-guidance devices. It is within the background of this increased interest in the utility of MRI in radiotherapy treatment planning that this paper is couched. The paper outlines publications that deal with standard MRI sequences used in current clinical practice. It then discusses the potential for using processed functional diffusion maps (fDM) derived from diffusion weighted image sequences in tracking tumor activity and tumor recurrence. Next, this paper reviews publications that describe the use of MRI in patient-management applications that may, in turn, be relevant to radiotherapy treatment planning. The review briefly discusses the concepts behind functional techniques such as dynamic contrast enhanced (DCE), diffusion-weighted (DW) MRI sequences and magnetic resonance spectroscopic imaging (MRSI). Significant applications of MR are discussed in terms of the following treatment sites: brain, head and neck, breast, lung, prostate and cervix. While not yet routine, the use of apparent diffusion coefficient (ADC) map analysis indicates an exciting future application for functional MRI. Although DW-MRI has not yet been routinely used in boost adaptive techniques, it is being assessed in cohort studies for sub-volume boosting in prostate tumors. PMID:23617289

Assessment of mediastinal tumors with diffusion-weighted single-shot echo-planar MRI.

PubMed

Razek, Ahmed Abdel; Elmorsy, Ahmed; Elshafey, Mohsen; Elhadedy, Tamer; Hamza, Osama

2009-09-01

To assess the role of diffusion-weighted single-shot echo-planar magnetic resonance imaging (MRI) in patients with mediastinal tumors. Prospective study was conducted on 45 consecutive patients (29 male, 16 female, age 22-66 years, mean 41 years) with mediastinal tumor. They underwent diffusion-weighted single-shot echo-planar MRI of the mediastinum with a b-factor of 0, 300, and 600 sec/mm(2). The apparent diffusion coefficient (ADC) value of the mediastinal tumor was correlated with the histopathological findings. The mean ADC value of malignant mediastinal tumors was 1.09 +/- 0.25 x 10(-3) mm(2)/sec, and of benign tumors was 2.38 +/- 0.56 x 10(-3) mm(2)/sec. There was a significant difference in the mean ADC value between malignant and benign tumors (P = 0.001) and within different grades of malignancy (0.001). When an ADC value of 1.56 x 10(-3) mm(2)/sec was used as a threshold value for differentiating malignant from benign tumor, the best results were obtained with an accuracy of 95%, sensitivity of 96%, specificity of 94%, positive predictive value of 94%, negative predictive value of 96%, and area under the curve of 0.938. The ADC value is a noninvasive parameter that can be used for differentiation of malignant from benign mediastinal tumors and grading of mediastinal malignancy.

Gene interference regulates aquaporin-4 expression in swollen tissue of rats with cerebral ischemic edema

PubMed Central

Hu, Hui; Lu, Hong; He, Zhanping; Han, Xiangjun; Chen, Jing; Tu, Rong

2012-01-01

To investigate the effects of mRNA interference on aquaporin-4 expression in swollen tissue of rats with ischemic cerebral edema, and diagnose the significance of diffusion-weighted MRI, we injected 5 μL shRNA- aquaporin-4 (control group) or siRNA- aquaporin-4 solution (1:800) (RNA interference group) into the rat right basal ganglia immediately before occlusion of the middle cerebral artery. At 0.25 hours after occlusion of the middle cerebral artery, diffusion-weighted MRI displayed a high signal; within 2 hours, the relative apparent diffusion coefficient decreased markedly, aquaporin-4 expression increased rapidly, and intracellular edema was obviously aggravated; at 4 and 6 hours, the relative apparent diffusion coefficient slowly returned to control levels, aquaporin-4 expression slightly increased, and angioedema was observed. In the RNA interference group, during 0.25–6 hours after injection of siRNA- aquaporin-4 solution, the relative apparent diffusion coefficient slightly fluctuated and aquaporin-4 expression was upregulated; during 0.5–4 hours, the relative apparent diffusion coefficient was significantly higher, while aquaporin-4 expression was significantly lower when compared with the control group, and intracellular edema was markedly reduced; at 0.25 and 6 hours, the relative apparent diffusion coefficient and aquaporin-4 expression were similar when compared with the control group; obvious angioedema remained at 6 hours. Pearson's correlation test results showed that aquaporin-4 expression was negatively correlated with the apparent diffusion coefficient (r = −0.806, P < 0.01). These findings suggest that upregulated aquaporin-4 expression is likely to be the main molecular mechanism of intracellular edema and may be the molecular basis for decreased relative apparent diffusion coefficient. Aquaporin-4 gene interference can effectively inhibit the upregulation of aquaporin-4 expression during the stage of intracellular edema with time-effectiveness. Moreover, diffusion-weighted MRI can accurately detect intracellular edema. PMID:25657707

Geometric distortion correction in prostate diffusion-weighted MRI and its effect on quantitative apparent diffusion coefficient analysis.

PubMed

Nketiah, Gabriel; Selnaes, Kirsten M; Sandsmark, Elise; Teruel, Jose R; Krüger-Stokke, Brage; Bertilsson, Helena; Bathen, Tone F; Elschot, Mattijs

2018-05-01

To evaluate the effect of correction for B 0 inhomogeneity-induced geometric distortion in echo-planar diffusion-weighted imaging on quantitative apparent diffusion coefficient (ADC) analysis in multiparametric prostate MRI. Geometric distortion correction was performed in echo-planar diffusion-weighted images (b = 0, 50, 400, 800 s/mm 2 ) of 28 patients, using two b 0 scans with opposing phase-encoding polarities. Histology-matched tumor and healthy tissue volumes of interest delineated on T 2 -weighted images were mapped to the nondistortion-corrected and distortion-corrected data sets by resampling with and without spatial coregistration. The ADC values were calculated on the volume and voxel level. The effect of distortion correction on ADC quantification and tissue classification was evaluated using linear-mixed models and logistic regression, respectively. Without coregistration, the absolute differences in tumor ADC (range: 0.0002-0.189 mm 2 /s×10 -3 (volume level); 0.014-0.493 mm 2 /s×10 -3 (voxel level)) between the nondistortion-corrected and distortion-corrected were significantly associated (P < 0.05) with distortion distance (mean: 1.4 ± 1.3 mm; range: 0.3-5.3 mm). No significant associations were found upon coregistration; however, in patients with high rectal gas residue, distortion correction resulted in improved spatial representation and significantly better classification of healthy versus tumor voxels (P < 0.05). Geometric distortion correction in DWI could improve quantitative ADC analysis in multiparametric prostate MRI. Magn Reson Med 79:2524-2532, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

Evaluation of three inverse problem models to quantify skin microcirculation using diffusion-weighted MRI

NASA Astrophysics Data System (ADS)

Cordier, G.; Choi, J.; Raguin, L. G.

2008-11-01

Skin microcirculation plays an important role in diseases such as chronic venous insufficiency and diabetes. Magnetic resonance imaging (MRI) can provide quantitative information with a better penetration depth than other noninvasive methods, such as laser Doppler flowmetry or optical coherence tomography. Moreover, successful MRI skin studies have recently been reported. In this article, we investigate three potential inverse models to quantify skin microcirculation using diffusion-weighted MRI (DWI), also known as q-space MRI. The model parameters are estimated based on nonlinear least-squares (NLS). For each of the three models, an optimal DWI sampling scheme is proposed based on D-optimality in order to minimize the size of the confidence region of the NLS estimates and thus the effect of the experimental noise inherent to DWI. The resulting covariance matrices of the NLS estimates are predicted by asymptotic normality and compared to the ones computed by Monte-Carlo simulations. Our numerical results demonstrate the effectiveness of the proposed models and corresponding DWI sampling schemes as compared to conventional approaches.

Functional and structural correlates of magnetic resonance patterns in a new in vitro model of cerebral ischemia by transient occlusion of the medial cerebral artery.

PubMed

Breschi, Gian Luca; Librizzi, Laura; Pastori, Chiara; Zucca, Ileana; Mastropietro, Alfonso; Cattalini, Alessandro; de Curtis, Marco

2010-08-01

Magnetic resonance imaging (MRI) during the acute phase of a stroke contributes to recognize ischemic regions and is potentially useful to predict clinical outcome. Yet, the functional significance of early MRI alterations during brain ischemia is not clearly understood. We achieved an experimental study to interpret MRI signals in a novel model of focal ischemia in the in vitro isolated guinea pig brain. By combining neurophysiological and morphological analysis with MR-imaging, we evaluated the suitability of MR to identify ischemic and peri-ischemic regions. Extracellular recordings demonstrated depolarizations in the ischemic core, but not in adjacent areas, where evoked activity was preserved and brief peri-infarct depolarizations occurred. Diffusion-weighted MRI and immunostaining performed after neurophysiological characterization showed changes restricted to the core region. Diffusion-weighted MR alterations did not include the penumbra region characterized by peri-infarct depolarizations. Therefore, by comparing neurophysiological, imaging and anatomical data, we can conclude that DW-MRI underestimates the extension of the tissue damage involved in brain ischemia.

Studying microstructure and microstructural changes in plant tissues by advanced diffusion magnetic resonance imaging techniques

PubMed Central

Morozov, Darya; Tal, Iris; Pisanty, Odelia; Shani, Eilon

2017-01-01

Abstract As sessile organisms, plants must respond to the environment by adjusting their growth and development. Most of the plant body is formed post-embryonically by continuous activity of apical and lateral meristems. The development of lateral adventitious roots is a complex process, and therefore the development of methods that can visualize, non-invasively, the plant microstructure and organ initiation that occur during growth and development is of paramount importance. In this study, relaxation-based and advanced diffusion magnetic resonance imaging (MRI) methods including diffusion tensor (DTI), q-space diffusion imaging (QSI), and double-pulsed-field-gradient (d-PFG) MRI, at 14.1 T, were used to characterize the hypocotyl microstructure and the microstructural changes that occurred during the development of lateral adventitious roots in tomato. Better contrast was observed in relaxation-based MRI using higher in-plane resolution but this also resulted in a significant reduction in the signal-to-noise ratio of the T2-weighted MR images. Diffusion MRI revealed that water diffusion is highly anisotropic in the vascular cylinder. QSI and d-PGSE MRI showed that in the vascular cylinder some of the cells have sizes in the range of 6–10 μm. The MR images captured cell reorganization during adventitious root formation in the periphery of the primary vascular bundles, adjacent to the xylem pole that broke through the cortex and epidermis layers. This study demonstrates that MRI and diffusion MRI methods allow the non-invasive study of microstructural features of plants, and enable microstructural changes associated with adventitious root formation to be followed. PMID:28398563

A Framework for Linear and Non-Linear Registration of Diffusion-Weighted MRIs Using Angular Interpolation

PubMed Central

Duarte-Carvajalino, Julio M.; Sapiro, Guillermo; Harel, Noam; Lenglet, Christophe

2013-01-01

Registration of diffusion-weighted magnetic resonance images (DW-MRIs) is a key step for population studies, or construction of brain atlases, among other important tasks. Given the high dimensionality of the data, registration is usually performed by relying on scalar representative images, such as the fractional anisotropy (FA) and non-diffusion-weighted (b0) images, thereby ignoring much of the directional information conveyed by DW-MR datasets itself. Alternatively, model-based registration algorithms have been proposed to exploit information on the preferred fiber orientation(s) at each voxel. Models such as the diffusion tensor or orientation distribution function (ODF) have been used for this purpose. Tensor-based registration methods rely on a model that does not completely capture the information contained in DW-MRIs, and largely depends on the accurate estimation of tensors. ODF-based approaches are more recent and computationally challenging, but also better describe complex fiber configurations thereby potentially improving the accuracy of DW-MRI registration. A new algorithm based on angular interpolation of the diffusion-weighted volumes was proposed for affine registration, and does not rely on any specific local diffusion model. In this work, we first extensively compare the performance of registration algorithms based on (i) angular interpolation, (ii) non-diffusion-weighted scalar volume (b0), and (iii) diffusion tensor image (DTI). Moreover, we generalize the concept of angular interpolation (AI) to non-linear image registration, and implement it in the FMRIB Software Library (FSL). We demonstrate that AI registration of DW-MRIs is a powerful alternative to volume and tensor-based approaches. In particular, we show that AI improves the registration accuracy in many cases over existing state-of-the-art algorithms, while providing registered raw DW-MRI data, which can be used for any subsequent analysis. PMID:23596381

A Framework for Linear and Non-Linear Registration of Diffusion-Weighted MRIs Using Angular Interpolation.

PubMed

Duarte-Carvajalino, Julio M; Sapiro, Guillermo; Harel, Noam; Lenglet, Christophe

2013-01-01

Registration of diffusion-weighted magnetic resonance images (DW-MRIs) is a key step for population studies, or construction of brain atlases, among other important tasks. Given the high dimensionality of the data, registration is usually performed by relying on scalar representative images, such as the fractional anisotropy (FA) and non-diffusion-weighted (b0) images, thereby ignoring much of the directional information conveyed by DW-MR datasets itself. Alternatively, model-based registration algorithms have been proposed to exploit information on the preferred fiber orientation(s) at each voxel. Models such as the diffusion tensor or orientation distribution function (ODF) have been used for this purpose. Tensor-based registration methods rely on a model that does not completely capture the information contained in DW-MRIs, and largely depends on the accurate estimation of tensors. ODF-based approaches are more recent and computationally challenging, but also better describe complex fiber configurations thereby potentially improving the accuracy of DW-MRI registration. A new algorithm based on angular interpolation of the diffusion-weighted volumes was proposed for affine registration, and does not rely on any specific local diffusion model. In this work, we first extensively compare the performance of registration algorithms based on (i) angular interpolation, (ii) non-diffusion-weighted scalar volume (b0), and (iii) diffusion tensor image (DTI). Moreover, we generalize the concept of angular interpolation (AI) to non-linear image registration, and implement it in the FMRIB Software Library (FSL). We demonstrate that AI registration of DW-MRIs is a powerful alternative to volume and tensor-based approaches. In particular, we show that AI improves the registration accuracy in many cases over existing state-of-the-art algorithms, while providing registered raw DW-MRI data, which can be used for any subsequent analysis.

Intravoxel Incoherent Motion MR Imaging in the Head and Neck: Correlation with Dynamic Contrast-Enhanced MR Imaging and Diffusion-Weighted Imaging.

PubMed

Xu, Xiao Quan; Choi, Young Jun; Sung, Yu Sub; Yoon, Ra Gyoung; Jang, Seung Won; Park, Ji Eun; Heo, Young Jin; Baek, Jung Hwan; Lee, Jeong Hyun

2016-01-01

To investigate the correlation between perfusion- and diffusion-related parameters from intravoxel incoherent motion (IVIM) and those from dynamic contrast-enhanced MR imaging (DCE-MRI) and diffusion-weighted imaging in tumors and normal muscles of the head and neck. We retrospectively enrolled 20 consecutive patients with head and neck tumors with MR imaging performed using a 3T MR scanner. Tissue diffusivity (D), pseudo-diffusion coefficient (D(*)), and perfusion fraction (f) were derived from bi-exponential fitting of IVIM data obtained with 14 different b-values in three orthogonal directions. We investigated the correlation between D, f, and D(*) and model-free parameters from the DCE-MRI (wash-in, Tmax, Emax, initial AUC60, whole AUC) and the apparent diffusion coefficient (ADC) value in the tumor and normal masseter muscle using a whole volume-of-interest approach. Pearson's correlation test was used for statistical analysis. No correlation was found between f or D(*) and any of the parameters from the DCE-MRI in all patients or in patients with squamous cell carcinoma (p > 0.05). The ADC was significantly correlated with D values in the tumors (p < 0.001, r = 0.980) and muscles (p = 0.013, r = 0.542), despite its significantly higher value than D. The difference between ADC and D showed significant correlation with f values in the tumors (p = 0.017, r = 0.528) and muscles (p = 0.003, r = 0.630), but no correlation with D(*) (p > 0.05, respectively). Intravoxel incoherent motion shows no significant correlation with model-free perfusion parameters derived from the DCE-MRI but is feasible for the analysis of diffusivity in both tumors and normal muscles of the head and neck.

Non-contrast magnetic resonance imaging for bladder cancer: fused high b value diffusion-weighted imaging and T2-weighted imaging helps evaluate depth of invasion.

PubMed

Lee, Minsu; Shin, Su-Jin; Oh, Young Taik; Jung, Dae Chul; Cho, Nam Hoon; Choi, Young Deuk; Park, Sung Yoon

2017-09-01

To investigate the utility of fused high b value diffusion-weighted imaging (DWI) and T2-weighted imaging (T2WI) for evaluating depth of invasion in bladder cancer. We included 62 patients with magnetic resonance imaging (MRI) and surgically confirmed urothelial carcinoma in the urinary bladder. An experienced genitourinary radiologist analysed the depth of invasion (T stage <2 or ≥2) using T2WI, DWI, T2WI plus DWI, and fused DWI and T2WI (fusion MRI). Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV) and accuracy were investigated. Area under the curve (AUC) was analysed to identify T stage ≥2. The rate of patients with surgically confirmed T stage ≥2 was 41.9% (26/62). Sensitivity, specificity, PPV, NPV and accuracy were 50.0%, 55.6%, 44.8%, 60.6% and 53.2%, respectively, with T2WI; 57.7%, 77.8%, 65.2%, 71.8% and 69.4%, respectively, with DWI; 65.4%, 80.6%, 70.8%, 76.3% and 74.2%, respectively, with T2WI plus DWI and 80.8%, 77.8%, 72.4%, 84.9% and 79.0%, respectively, with fusion MRI. AUC was 0.528 with T2WI, 0.677 with DWI, 0.730 with T2WI plus DWI and 0.793 with fusion MRI for T stage ≥2. Fused high b value DWI and T2WI may be a promising non-contrast MRI technique for assessing depth of invasion in bladder cancer. • Accuracy of fusion MRI was 79.0% for T stage ≥2 in bladder cancer. • AUC of fusion MRI was 0.793 for T stage ≥2 in bladder cancer. • Diagnostic performance of fusion MRI was comparable with T2WI plus DWI. • As a non-contrast MRI technique, fusion MRI is useful for bladder cancer.

Differential diagnosis of benign and malignant breast masses using diffusion-weighted magnetic resonance imaging.

PubMed

Min, Qinghua; Shao, Kangwei; Zhai, Lulan; Liu, Wei; Zhu, Caisong; Yuan, Lixin; Yang, Jun

2015-02-07

Diffusion-weighted magnetic resonance imaging (DW-MRI) is different from conventional diagnostic methods and has the potential to delineate the microscopic anatomy of a target tissue or organ. The purpose of our study was to evaluate the value of DW-MRI in the diagnosis of benign and malignant breast masses, which would help the clinical surgeon to decide the scope and pattern of operation. A total of 52 female patients with palpable solid breast masses received breast MRI scans using routine sequences, dynamic contrast-enhanced imaging, and diffusion-weighted echo-planar imaging at b values of 400, 600, and 800 s/mm(2), respectively. Two regions of interest (ROIs) were plotted, with a smaller ROI for the highest signal and a larger ROI for the overall lesion. Apparent diffusion coefficient (ADC) values were calculated at three different b values for all detectable lesions and from two different ROIs. The sensitivity, specificity, positive predictive value, and positive likelihood ratio of DW-MRI were determined for comparison with histological results. A total of 49 (49/52, 94.2%) lesions were detected using DW-MRI, including 20 benign lesions (two lesions detected in the same patient) and 29 malignant lesions. Benign lesion had a higher mean ADC value than their malignant counterparts, regardless of b value. According to the receiver operating characteristic (ROC) curve, the smaller-range ROI was more effective in differentiation between benign and malignant lesions. The area under the ROC curve was the largest at a b value of 800 s/mm(2). With a threshold ADC value at 1.23 × 10(-3) mm(2)/s, DW-MRI achieved a sensitivity of 82.8%, specificity of 90.0%, positive predictive value of 92.3%, and positive likelihood ratio of 8.3 for differentiating benign and malignant lesions. DW-MRI is an accurate diagnostic tool for differentiation between benign and malignant breast lesions, with an optimal b value of 800 s/mm(2). A smaller-range ROI focusing on the highest signal has a better differential value.

In vivo tumor characterization using both MR and optical contrast agents with a hybrid MRI-DOT system

NASA Astrophysics Data System (ADS)

Lin, Yuting; Ghijsen, Michael; Thayer, David; Nalcioglu, Orhan; Gulsen, Gultekin

2011-03-01

Dynamic contrast enhanced MRI (DCE-MRI) has been proven to be the most sensitive modality in detecting breast lesions. Currently available MR contrast agent, Gd-DTPA, is a low molecular weight extracellular agent and can diffuse freely from the vascular space into interstitial space. Due to this reason, DCE-MRI has low sensitivity in differentiating benign and malignant tumors. Meanwhile, diffuse optical tomography (DOT) can be used to provide enhancement kinetics of an FDA approved optical contrast agent, ICG, which behaves like a large molecular weight optical agent due to its binding to albumin. The enhancement kinetics of ICG may have a potential to distinguish between the malignant and benign tumors and hence improve the specificity. Our group has developed a high speed hybrid MRI-DOT system. The DOT is a fully automated, MR-compatible, multi-frequency and multi-spectral imaging system. Fischer-344 rats bearing subcutaneous R3230 tumor are injected simultaneously with Gd-DTPA (0.1nmol/kg) and IC-Green (2.5mg/kg). The enhancement kinetics of both contrast agents are recorded simultaneously with this hybrid MRI-DOT system and evaluated for different tumors.

Simultaneous 68Ga-DOTATOC PET/MRI in patients with gastroenteropancreatic neuroendocrine tumors: initial results.

PubMed

Beiderwellen, Karsten J; Poeppel, Thorsten D; Hartung-Knemeyer, Verena; Buchbender, Christian; Kuehl, Hilmar; Bockisch, Andreas; Lauenstein, Thomas C

2013-05-01

The aim of this pilot study was to demonstrate the potential of simultaneously acquired 68-Gallium-DOTA-D-Phe1-Tyr3-octreotide (68Ga-DOTATOC) positron emission tomography/magnetic resonance imaging (PET/MRI) in comparison with 68Ga-DOTATOC PET/computed tomography (PET/CT) in patients with known gastroenteropancreatic neuroendocrine tumors (NETs). Eight patients (4 women and 4 men; mean [SD] age, 54 [17] years; median, 55 years; range 25-74 years) with histopathologically confirmed NET and scheduled 68Ga-DOTATOC PET/CT were prospectively enrolled for an additional integrated PET/MRI scan. Positron emission tomography/computed tomography was performed using a triple-phase contrast-enhanced full-dose protocol. Positron emission tomography/magnetic resonance imaging encompassed a diagnostic, contrast-enhanced whole-body MRI protocol. Two readers separately analyzed the PET/CT and PET/MRI data sets including their subscans in random order regarding lesion localization, count, and characterization on a 4-point ordinal scale (0, not visible; 1, benign; 2, indeterminate; and 3, malignant). In addition, each lesion was rated in consensus on a binary scale (allowing for benign/malignant only). Clinical imaging, existing prior examinations, and histopathology (if available) served as the standard of reference. In PET-positive lesions, the standardized uptake value (SUV max) was measured in consensus. A descriptive, case-oriented data analysis was performed, including determination of frequencies and percentages in detection of malignant, benign, and indeterminate lesions in connection to their localization. In addition, percentages in detection by a singular modality (such as PET, CT, or MRI) were calculated. Interobserver variability was calculated (Cohen's κ). The SUVs in the lesions in PET/CT and PET/MRI were measured, and the correlation coefficient (Pearson, 2-tailed) was calculated. According to the reference standard, 5 of the 8 patients had malignant NET lesions at the time of the examination. A total of 4 patients were correctly identified by PET/CT, with the PET and CT component correctly identifying 3 patients each. All 5 patients positive for NET disease were correctly identified by PET/MRI, with the MRI subscan identifying all 5 patients and the PET subscan identifying 3 patients. All lesions considered as malignant in PET/CT were equally depicted in and considered using PET/MRI. One liver lesion rated as "indetermined" in PET/CT was identified as metastasis in PET/MRI because of a diffusion restriction in diffusion-weighted imaging. Of the 4 lung lesions characterized in PET/CT, only 1 was depicted in PET/MRI. Of the 3 lymph nodes depicted in PET/CT, only 1 was characterized in PET/MRI. Interobserver reliability was equally very good in PET/CT (κ = 0.916) and PET/MRI (κ = 1.0). The SUV max measured in PET/CT and in PET/MRI showed a strong correlation (Pearson correlation coefficient, 0.996). This pilot study demonstrates the potential of 68Ga-DOTATOC PET/MRI in patients with gastroenteropancreatic NET, with special advantages in the characterization of abdominal lesions yet certain weaknesses inherent to MRI, such as lung metastases and hypersclerotic bone lesions.

Quantitative evaluation of multi-parametric MR imaging marker changes post-laser interstitial ablation therapy (LITT) for epilepsy

NASA Astrophysics Data System (ADS)

Tiwari, Pallavi; Danish, Shabbar; Wong, Stephen; Madabhushi, Anant

2013-03-01

Laser-induced interstitial thermal therapy (LITT) has recently emerged as a new, less invasive alternative to craniotomy for treating epilepsy; which allows for focussed delivery of laser energy monitored in real time by MRI, for precise removal of the epileptogenic foci. Despite being minimally invasive, the effects of laser ablation on the epileptogenic foci (reflected by changes in MR imaging markers post-LITT) are currently unknown. In this work, we present a quantitative framework for evaluating LITT-related changes by quantifying per-voxel changes in MR imaging markers which may be more reflective of local treatment related changes (TRC) that occur post-LITT, as compared to the standard volumetric analysis which involves monitoring a more global volume change across pre-, and post-LITT MRI. Our framework focuses on three objectives: (a) development of temporal MRI signatures that characterize TRC corresponding to patients with seizure freedom by comparing differences in MR imaging markers and monitoring them over time, (b) identification of the optimal time point when early LITT induced effects (such as edema and mass effect) subside by monitoring TRC at subsequent time-points post-LITT, and (c) identification of contributions of individual MRI protocols towards characterizing LITT-TRC for epilepsy by identifying MR markers that change most dramatically over time and employ individual contributions to create a more optimal weighted MP-MRI temporal profile that can better characterize TRC compared to any individual imaging marker. A cohort of patients were monitored at different time points post-LITT via MP-MRI involving T1-w, T2-w, T2-GRE, T2-FLAIR, and apparent diffusion coefficient (ADC) protocols. Post affine registration of individual MRI protocols to a reference MRI protocol pre-LITT, differences in individual MR markers are computed on a per-voxel basis, at different time-points with respect to baseline (pre-LITT) MRI as well as across subsequent time-points. A time-dependent MRI profile corresponding to successful (seizure-free) is then created that captures changes in individual MR imaging markers over time. Our preliminary analysis on two patient studies suggests that (a) LITT related changes (attributed to swelling and edema) appear to subside within 4-weeks post-LITT, (b) ADC may be more sensitive for evaluating early TRC (up to 3-months), and T1-w may be more sensitive in evaluating early delayed TRC (1-month, 3-months), while T2-w and T2-FLAIR appeared to be more sensitive in identifying late TRC (around 6-months post-LITT) compared to the other MRI protocols under evaluation. T2-GRE was found to be only nominally sensitive in identifying TRC at any follow-up time-point post-LITT. The framework presented in this work thus serves as an important precursor to a comprehensive treatment evaluation framework that can be used to identify sensitive MR markers corresponding to patient response (seizure-freedom or seizure recurrence), with an ultimate objective of making prognostic predictions about patient outcome post-LITT.

Detection of the index tumour and tumour volume in prostate cancer using T2-weighted and diffusion-weighted magnetic resonance imaging (MRI) alone.

PubMed

Rud, Erik; Klotz, Dagmar; Rennesund, Kristin; Baco, Eduard; Berge, Viktor; Lien, Diep; Svindland, Aud; Lundeby, Eskild; Berg, Rolf E; Eri, Lars M; Eggesbø, Heidi B

2014-12-01

To examine the performance of T2-weighted (T2W) and diffusion-weighted (DW) magnetic resonance imaging (MRI) for detecting the index tumour in patients with prostate cancer and to examine the agreement between MRI and histology when assessing tumour volume (TV) and overall tumour burden. The study included 199 consecutive patients with biopsy confirmed prostate cancer randomised to MRI before radical prostatectomy from December 2009 to July 2012. MRI-detected tumours (MRTs) were ranked from 1 to 3 according to decreasing volume and were compared with histologically detected tumours (HTs) ranked from 1 to 3, with HT 1 = index tumour. Whole-mount section histology was used as a reference standard. The TVs of true-positive MRTs (MRTVs 1-3) were compared with the TVs found by histology (HTVs 1-3). All tumours were registered on a 30-sector map and by classifying each sector as positive/negative, the rate of true-positive and -negative sectors was calculated. The detection rate for the HT 1 (index tumour) was 92%; HT 2, 45%; and HT 3, 37%. The MRTV 1-3 vs the HTV 1-3 were 2.8 mL vs 4.0 mL (index tumour, P < 0.001), 1.0 mL vs 0.9 mL (tumour 2, P = 0.413), and 0.6 mL vs 0.5 mL (tumour 3, P = 0.492). The rate of true-positive and -negative sectors was 50% and 88%, κ = 0.39. A combination of T2W and DW MRI detects the index tumour in 92% of cases, although MRI underestimates both TV and tumour burden compared with histology. © 2014 The Authors. BJU International © 2014 BJU International.

Assessment of image quality of a radiotherapy-specific hardware solution for PET/MRI in head and neck cancer patients.

PubMed

Winter, René M; Leibfarth, Sara; Schmidt, Holger; Zwirner, Kerstin; Mönnich, David; Welz, Stefan; Schwenzer, Nina F; la Fougère, Christian; Nikolaou, Konstantin; Gatidis, Sergios; Zips, Daniel; Thorwarth, Daniela

2018-05-07

Functional PET/MRI has great potential to improve radiotherapy planning (RTP). However, data integration requires imaging with radiotherapy-specific patient positioning. Here, we investigated the feasibility and image quality of radiotherapy-customized PET/MRI in head-and-neck cancer (HNC) patients using a dedicated hardware setup. Ten HNC patients were examined with simultaneous PET/MRI before treatment, with radiotherapy and diagnostic scan setup, respectively. We tested feasibility of radiotherapy-specific patient positioning and compared the image quality between both setups by pairwise image analysis of 18 F-FDG-PET, T1/T2-weighted and diffusion-weighted MRI. For image quality assessment, similarity measures including average symmetric surface distance (ASSD) of PET and MR-based tumor contours, MR signal-to-noise ratio (SNR) and mean apparent diffusion coefficient (ADC) value were used. PET/MRI in radiotherapy position was feasible - all patients were successfully examined. ASSD (median/range) of PET and MR contours was 0.6 (0.4-1.2) and 0.9 (0.5-1.3) mm, respectively. For T2-weighted MRI, a reduced SNR of -26.2% (-39.0--11.7) was observed with radiotherapy setup. No significant difference in mean ADC was found. Simultaneous PET/MRI in HNC patients using radiotherapy positioning aids is clinically feasible. Though SNR was reduced, the image quality obtained with a radiotherapy setup meets RTP requirements and the data can thus be used for personalized RTP. Copyright © 2018 The Author(s). Published by Elsevier B.V. All rights reserved.

Detection of liver metastasis: is diffusion-weighted imaging needed in Gd-EOB-DTPA-enhanced MR imaging for evaluation of colorectal liver metastases?

PubMed

Tajima, Taku; Akahane, Masaaki; Takao, Hidemasa; Akai, Hiroyuki; Kiryu, Shigeru; Imamura, Hiroshi; Watanabe, Yasushi; Kokudo, Norihiro; Ohtomo, Kuni

2012-10-01

We compared diagnostic ability for detecting hepatic metastases between gadolinium ethoxy benzyl diethylenetriamine pentaacetic acid (Gd-EOB-DTPA)-enhanced magnetic resonance imaging (MRI) and diffusion-weighted imaging (DWI) on a 1.5-T system, and determined whether DWI is necessary in Gd-EOB-DTPA-enhanced MRI for diagnosing colorectal liver metastases. We assessed 29 consecutive prospectively enrolled patients with suspected metachronous colorectal liver metastases; all patients underwent surgery and had preoperative Gd-EOB-DTPA-enhanced MRI. Overall detection rate, sensitivity for detecting metastases and benign lesions, positive predictive value, and diagnostic accuracy (Az value) were compared among three image sets [unenhanced MRI (DWI set), Gd-EOB-DTPA-enhanced MRI excluding DWI (EOB set), and combined set]. Gd-EOB-DTPA-enhanced MRI yielded better overall detection rate (77.8-79.0 %) and sensitivity (87.1-89.4 %) for detecting metastases than the DWI set (55.9 % and 64.7 %, respectively) for one observer (P < 0.001). No statistically significant difference was seen between the EOB and combined sets, although several metastases were newly detected on additional DWI. Gd-EOB-DTPA-enhanced MRI yielded a better overall detection rate and higher sensitivity for detecting metastases compared with unenhanced MRI. Additional DWI may be able to reduce oversight of lesions in Gd-EOB-DTPA-enhanced 1.5-T MRI for detecting colorectal liver metastases.

Value of diffusion-weighted MRI and apparent diffusion coefficient measurements for predicting the response of locally advanced rectal cancer to neoadjuvant chemoradiotherapy.

PubMed

Iannicelli, Elsa; Di Pietropaolo, Marco; Pilozzi, Emanuela; Osti, Mattia Falchetto; Valentino, Maria; Masoni, Luigi; Ferri, Mario

2016-10-01

The aim of our study was to assess the performance value of magnetic resonance imaging (MRI) in the restaging of locally advanced rectal cancer after neoadjuvant chemoradiotherapy (CRT) and in the identification of good vs. poor responders to neoadjuvant therapy. A total of 34 patients with locally advanced rectal cancer underwent MRI prior to and after CRT. T stage and tumor regression grade (TRG) on post-CRT MRI was compared with the pathological staging ypT and TRG. Tumor volume and the apparent diffusion coefficient (ADC) were measured using diffusion-weighted imaging (DWI) before and after neoadjuvant CRT; the percentage of tumor volume reduction and the change of ADC (ΔADC) was also calculated. ADC parameters and the percentage of tumor volume reduction were correlated to histopathological results. The diagnostic performance of ADC and volume reduction to assess tumor response was evaluated by calculating the area under the ROC curve and the optimal cut-off values. A significant correlation between the T stage and the TRG defined in DW-MRI after CRT and the ypT and the TRG observed on the surgical specimens was found (p = 0.001; p < 0.001). The mean post-CRT ADC and ΔADC in responder patients was significantly higher compared to non-responder ones (p = 0.001; p = 0.01). Furthermore, the mean post-CRT ADC values were significantly higher in tumors with T-downstage (p = 0.01). DW-MRI may have a significant role in the restaging and in the evaluation of post-CRT response of locally advanced rectal cancer. Quantitative analysis of DWI through ADC map may result in a promising noninvasive tool to evaluate the response to therapy.

Advanced MRI Methods for Assessment of Chronic Liver Disease

PubMed Central

Taouli, Bachir; Ehman, Richard L.; Reeder, Scott B.

2010-01-01

MRI plays an increasingly important role for assessment of patients with chronic liver disease. MRI has numerous advantages, including lack of ionizing radiation and the possibility of performing multiparametric imaging. With recent advances in technology, advanced MRI methods such as diffusion-, perfusion-weighted MRI, MR elastography, chemical shift based fat-water separation and MR spectroscopy can now be applied to liver imaging. We will review the respective roles of these techniques for assessment of chronic liver disease. PMID:19542391

Magnetic resonance characteristics and susceptibility weighted imaging of the brain in gadolinium encephalopathy.

PubMed

Samardzic, Dejan; Thamburaj, Krishnamoorthy

2015-01-01

To report the brain imaging features on magnetic resonance imaging (MRI) in inadvertent intrathecal gadolinium administration. A 67-year-old female with gadolinium encephalopathy from inadvertent high dose intrathecal gadolinium administration during an epidural steroid injection was studied with multisequence 3T MRI. T1-weighted imaging shows pseudo-T2 appearance with diffusion of gadolinium into the brain parenchyma, olivary bodies, and membranous labyrinth. Nulling of cerebrospinal fluid (CSF) signal is absent on fluid attenuation recovery (FLAIR). Susceptibility-weighted imaging (SWI) demonstrates features similar to subarachnoid hemorrhage. CT may demonstrate a pseudo-cerebral edema pattern given the high attenuation characteristics of gadolinium. Intrathecal gadolinium demonstrates characteristic imaging features on MRI of the brain and may mimic subarachnoid hemorrhage on susceptibility-weighted imaging. Identifying high dose gadolinium within the CSF spaces on MRI is essential to avoid diagnostic and therapeutic errors. Copyright © 2013 by the American Society of Neuroimaging.

Diagnostic performance of conventional MRI parameters and apparent diffusion coefficient values in differentiating between benign and malignant soft-tissue tumours.

PubMed

Song, Y; Yoon, Y C; Chong, Y; Seo, S W; Choi, Y-L; Sohn, I; Kim, M-J

2017-08-01

To compare the abilities of conventional magnetic resonance imaging (MRI) and apparent diffusion coefficient (ADC) in differentiating between benign and malignant soft-tissue tumours (STT). A total of 123 patients with STT who underwent 3 T MRI, including diffusion-weighted imaging (DWI), were retrospectively analysed using variate conventional MRI parameters, ADC mean and ADC min . For the all-STT group, the correlation between the malignant STT conventional MRI parameters, except deep compartment involvement, compared to those of benign STT were statistically significant with univariate analysis. Maximum diameter of the tumour (p=0.001; odds ratio [OR], 8.97) and ADC mean (p=0.020; OR, 4.30) were independent factors with multivariate analysis. For the non-myxoid non-haemosiderin STT group, signal heterogeneity on axial T1-weighted imaging (T1WI; p=0.017), ADC mean , and ADC min (p=0.001, p=0.001), showed significant differences with univariate analysis between malignancy and benignity. Signal heterogeneity in axial T1WI (p=0.025; OR, 12.64) and ADC mean (p=0.004; OR, 33.15) were independent factors with multivariate analysis. ADC values as well as conventional MRI parameters were useful in differentiating between benign and malignant STT. The ADC mean was the most powerful diagnostic parameter in non-myxoid non-haemosiderin STT. Copyright © 2017 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

Unexpected recovery of function after severe traumatic brain injury: the limits of early neuroimaging-based outcome prediction.

PubMed

Edlow, Brian L; Giacino, Joseph T; Hirschberg, Ronald E; Gerrard, Jason; Wu, Ona; Hochberg, Leigh R

2013-12-01

Prognostication in the early stage of traumatic coma is a common challenge in the neuro-intensive care unit. We report the unexpected recovery of functional milestones (i.e., consciousness, communication, and community reintegration) in a 19-year-old man who sustained a severe traumatic brain injury. The early magnetic resonance imaging (MRI) findings, at the time, suggested a poor prognosis. During the first year of the patient's recovery, MRI with diffusion tensor imaging and T2*-weighted imaging was performed on day 8 (coma), day 44 (minimally conscious state), day 198 (post-traumatic confusional state), and day 366 (community reintegration). Mean apparent diffusion coefficient (ADC) and fractional anisotropy values in the corpus callosum, cerebral hemispheric white matter, and thalamus were compared with clinical assessments using the Disability Rating Scale (DRS). Extensive diffusion restriction in the corpus callosum and bihemispheric white matter was observed on day 8, with ADC values in a range typically associated with neurotoxic injury (230-400 × 10(-6 )mm(2)/s). T2*-weighted MRI revealed widespread hemorrhagic axonal injury in the cerebral hemispheres, corpus callosum, and brainstem. Despite the presence of severe axonal injury on early MRI, the patient regained the ability to communicate and perform activities of daily living independently at 1 year post-injury (DRS = 8). MRI data should be interpreted with caution when prognosticating for patients in traumatic coma. Recovery of consciousness and community reintegration are possible even when extensive traumatic axonal injury is demonstrated by early MRI.

Regional brain injury on conventional and diffusion weighted MRI is associated with outcome after pediatric cardiac arrest.

PubMed

Fink, Ericka L; Panigrahy, A; Clark, R S B; Fitz, C R; Landsittel, D; Kochanek, P M; Zuccoli, G

2013-08-01

To assess regional brain injury on magnetic resonance imaging (MRI) after pediatric cardiac arrest (CA) and to associate regional injury with patient outcome and effects of hypothermia therapy for neuroprotection. We performed a retrospective chart review with prospective imaging analysis. Children between 1 week and 17 years of age who had a brain MRI in the first 2 weeks after CA without other acute brain injury between 2002 and 2008 were included. Brain MRI (1.5 T General Electric, Milwaukee, WI, USA) images were analyzed by 2 blinded neuroradiologists with adjudication; images were visually graded. Brain lobes, basal ganglia, thalamus, brain stem, and cerebellum were analyzed using T1, T2, and diffusion-weighted images (DWI). We examined 28 subjects with median age 1.9 years (IQR 0.4-13.0) and 19 (68 %) males. Increased intensity on T2 in the basal ganglia and restricted diffusion in the brain lobes were associated with unfavorable outcome (all P < 0.05). Therapeutic hypothermia had no effect on regional brain injury. Repeat brain MRI was infrequently performed but demonstrated evolution of lesions. Children with lesions in the basal ganglia on conventional MRI and brain lobes on DWI within the first 2 weeks after CA represent a group with increased risk of poor outcome. These findings may be important for developing neuroprotective strategies based on regional brain injury and for evaluating response to therapy in interventional clinical trials.

SU-F-R-06: Traumatic Brachial Plexus Injury Imaging, Developing a Coherent Clinical Protocol From Literature Review Through Practice

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

Wu, D; France, E; Lambert, J

Purpose: Medical Physics teams can now play a critical role to help plan and provide studied approaches for traumatic brachial plexus MR imaging (tbpMRI). This is especially important for coordination with uncommon applications, since it is challenging to select the right modality, parameters, and train technologists on the essential components. For this work, we started with a review of the medical literature, performed crossover/volunteer studies to bring tbpMRI to practice with greater image QC and protocol management. Methods: To the best of our knowledge, we reviewed the known searchable domain for tbpMRI. We found 69 total articles since 2000. Articlesmore » were evaluated with our published protocol for literature management (LIMES3). Two physicists and two radiologists condensed the information from all articles into a knowledgebase. Results: The initial literature demonstrated great heterogeneity, which was a sign that this area needed greater consistency. Despite inconsistency and imprecision, we extracted the most relevant targets using our long-term experience with protocol development in MSK. We ran volunteers on six different magnets of various field strengths with multiple receiver coils, and rebuilt a coherent protocol for tbpMRI. Our radiologists rated LIMES3 work as superior. We have received referrals from the ER and have conducted four patient evaluations. Conclusion: Traumatic brachial plexus MRI has great possible benefits for patients. This work supports the complexity of tbpMRI scanning. As this is rarely performed, it requires a more diligent protocol workflow, coordination of caregivers, and education within multiple clinical departments. Choosing the correct imaging exam can be critical, as patients can have significant neuropathy and/or paralysis. The LIMES3 protocol is well liked at our institution, and forms the cornerstone of understanding for our work. Our literature management led to a better clinical protocol creation despite the diffuse and inconclusive information presented in the existing medical literature.« less

Advanced magnetic resonance imaging in glioblastoma: a review.

PubMed

Shukla, Gaurav; Alexander, Gregory S; Bakas, Spyridon; Nikam, Rahul; Talekar, Kiran; Palmer, Joshua D; Shi, Wenyin

2017-08-01

Glioblastoma, the most common and most rapidly progressing primary malignant tumor of the central nervous system, continues to portend a dismal prognosis, despite improvements in diagnostic and therapeutic strategies over the last 20 years. The standard of care radiographic characterization of glioblastoma is magnetic resonance imaging (MRI), which is a widely utilized examination in the diagnosis and post-treatment management of patients with glioblastoma. Basic MRI modalities available from any clinical scanner, including native T1-weighted (T1w) and contrast-enhanced (T1CE), T2-weighted (T2w), and T2-fluid-attenuated inversion recovery (T2-FLAIR) sequences, provide critical clinical information about various processes in the tumor environment. In the last decade, advanced MRI modalities are increasingly utilized to further characterize glioblastomas more comprehensively. These include multi-parametric MRI sequences, such as dynamic susceptibility contrast (DSC), dynamic contrast enhancement (DCE), higher order diffusion techniques such as diffusion tensor imaging (DTI), and MR spectroscopy (MRS). Significant efforts are ongoing to implement these advanced imaging modalities into improved clinical workflows and personalized therapy approaches. Functional MRI (fMRI) and tractography are increasingly being used to identify eloquent cortices and important tracts to minimize postsurgical neuro-deficits. A contemporary review of the application of standard and advanced MRI in clinical neuro-oncologic practice is presented here.

A 1-minute full brain MR exam using a multicontrast EPI sequence.

PubMed

Skare, Stefan; Sprenger, Tim; Norbeck, Ola; Rydén, Henric; Blomberg, Lars; Avventi, Enrico; Engström, Mathias

2018-06-01

A new multicontrast echo-planar imaging (EPI)-based sequence is proposed for brain MRI, which can directly generate six MR contrasts (T 1 -FLAIR, T 2 -w, diffusion-weighted (DWI), apparent diffusion coefficient (ADC), T2*-w, T 2 -FLAIR) in 1 min with full brain coverage. This could enable clinical MR clinical screening in similar time as a conventional CT exam but with more soft-tissue information. Eleven sequence modules were created as dynamic building blocks for the sequence. Two EPI readout modules were reused throughout the sequence and were prepended by other modules to form the desired MR contrasts. Two scan protocols were optimized with scan times of 55-75 s. Motion experiments were carried out on two volunteers to investigate the robustness against head motion. Scans on patients were carried out and compared to conventional clinical images. The pulse sequence is found to be robust against motion given its single-shot nature of each contrast. For excessive out-of-plane head motion, the T 1 -FLAIR and T 2 -FLAIR contrasts suffer from incomplete inversion. Despite lower signal-to-noise ratio (SNR) and resolution, the 1-min multicontrast EPI data show promising correspondence with conventional diagnostic scans on patients. A 1 min multicontrast brain MRI scan based on EPI readouts has been presented in this feasibility study. Preliminary data show potential for clinical brain MRI use with minimal bore time for the patient. Such short examination time could be useful (e.g., for screening and acute stroke). The sequence may also help planning conventional brain MRI scans if run at the beginning of an examination. Magn Reson Med 79:3045-3054, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

Stroke With Unknown Time of Symptom Onset: Baseline Clinical and Magnetic Resonance Imaging Data of the First Thousand Patients in WAKE-UP (Efficacy and Safety of MRI-Based Thrombolysis in Wake-Up Stroke: A Randomized, Doubleblind, Placebo-Controlled Trial).

PubMed

Thomalla, Götz; Boutitie, Florent; Fiebach, Jochen B; Simonsen, Claus Z; Nighoghossian, Norbert; Pedraza, Salvador; Lemmens, Robin; Roy, Pascal; Muir, Keith W; Ebinger, Martin; Ford, Ian; Cheng, Bastian; Galinovic, Ivana; Cho, Tae-Hee; Puig, Josep; Thijs, Vincent; Endres, Matthias; Fiehler, Jens; Gerloff, Christian

2017-03-01

We describe clinical and magnetic resonance imaging (MRI) characteristics of stroke patients with unknown time of symptom onset potentially eligible for thrombolysis from a large prospective cohort. We analyzed baseline data from WAKE-UP (Efficacy and Safety of MRI-Based Thrombolysis in Wake-Up Stroke: A Randomized, Doubleblind, Placebo-Controlled Trial), an investigator-initiated, randomized, placebo-controlled trial of MRI-based thrombolysis in stroke patients with unknown time of symptom onset. MRI judgment included assessment of the mismatch between visibility of the acute ischemic lesion on diffusion-weighted imaging and fluid-attenuated inversion recovery. Of 1005 patients included, diffusion-weighted imaging and fluid-attenuated inversion recovery mismatch was present in 479 patients (48.0%). Patients with daytime-unwitnessed stroke (n=138, 13.7%) had a shorter delay between symptom recognition and hospital arrival (1.5 versus 1.8 hours; P =0.002), a higher National Institutes of Stroke Scale score on admission (8 versus 6; P <0.001), and more often aphasia (72.5% versus 34.0%; P <0.001) when compared with stroke patients waking up from nighttime sleep. Frequency of diffusion-weighted imaging and fluid-attenuated inversion recovery mismatch was comparable between both groups (43.7% versus 48.7%; P =0.30). Almost half of the patients with unknown time of symptom onset stroke otherwise eligible for thrombolysis had MRI findings making them likely to be within a time window for safe and effective thrombolysis. Patients with daytime onset unwitnessed stroke differ from wake-up stroke patients with regards to clinical characteristics but are comparable in terms of MRI characteristics of lesion age. URL: http://www.clinicaltrials.gov. Unique identifier: NCT01525290. URL: https://www.clinicaltrialsregister.eu. Unique identifier: 2011-005906-32. © 2017 American Heart Association, Inc.

Technique of diffusion weighted imaging and its application in stroke

NASA Astrophysics Data System (ADS)

Li, Enzhong; Tian, Jie; Han, Ying; Wang, Huifang; Li, Wu; He, Huiguang

2003-05-01

To study the application of diffusion weighted imaging and image post processing in the diagnosis of stroke, especially in acute stroke, 205 patients were examined by 1.5 T or 1.0 T MRI scanner and the images such as T1, T2 and diffusion weighted images were obtained. Image post processing was done with "3D Med System" developed by our lab to analyze data and acquire the apparent diffusion coefficient (ADC) map. In acute and subacute stage of stroke, the signal in cerebral infarction areas changed to hyperintensity in T2- and diffusion-weighted images, normal or hypointensity in T1-weighted images. In hyperacute stage, however, the signal was hyperintense just in the diffusion weighted imaes; others were normal. In the chronic stage, the signal in T1- and diffusion-weighted imaging showed hypointensity and hyperintensity in T2 weighted imaging. Because ADC declined obviously in acute and subacute stage of stroke, the lesion area was hypointensity in ADC map. With the development of the disease, ADC gradually recovered and then changed to hyperintensity in ADC map in chronic stage. Using diffusion weighted imaging and ADC mapping can make a diagnosis of stroke, especially in the hyperacute stage of stroke, and can differentiate acute and chronic stroke.

Unenhanced breast MRI (STIR, T2-weighted TSE, DWIBS): An accurate and alternative strategy for detecting and differentiating breast lesions.

PubMed

Telegrafo, Michele; Rella, Leonarda; Stabile Ianora, Amato Antonio; Angelelli, Giuseppe; Moschetta, Marco

2015-10-01

To assess the role of STIR, T2-weighted TSE and DWIBS sequences for detecting and characterizing breast lesions and to compare unenhanced (UE)-MRI results with contrast-enhanced (CE)-MRI and histological findings, having the latter as the reference standard. Two hundred eighty consecutive patients (age range, 27-73 years; mean age±standard deviation (SD), 48.8±9.8years) underwent MR examination with a diagnostic protocol including STIR, T2-weighted TSE, THRIVE and DWIBS sequences. Two radiologists blinded to both dynamic sequences and histological findings evaluated in consensus STIR, T2-weighted TSE and DWIBS sequences and after two weeks CE-MRI images searching for breast lesions. Sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and diagnostic accuracy for UE-MRI and CE-MRI were calculated. UE-MRI results were also compared with CE- MRI. UE-MRI sequences obtained sensitivity, specificity, diagnostic accuracy, PPV and NPV values of 94%, 79%, 86%, 79% and 94%, respectively. CE-MRI sequences obtained sensitivity, specificity, diagnostic accuracy, PPV and NPV values of 98%, 83%, 90%, 84% and 98%, respectively. No statistically significant difference between UE-MRI and CE-MRI was found. Breast UE-MRI could represent an accurate diagnostic tool and a valid alternative to CE-MRI for evaluating breast lesions. STIR and DWIBS sequences allow to detect breast lesions while T2-weighted TSE sequences and ADC values could be useful for lesion characterization. Copyright © 2015 Elsevier Inc. All rights reserved.

Diffusion-weighted imaging: Apparent diffusion coefficient histogram analysis for detecting pathologic complete response to chemoradiotherapy in locally advanced rectal cancer.

PubMed

Choi, Moon Hyung; Oh, Soon Nam; Rha, Sung Eun; Choi, Joon-Il; Lee, Sung Hak; Jang, Hong Seok; Kim, Jun-Gi; Grimm, Robert; Son, Yohan

2016-07-01

To investigate the usefulness of apparent diffusion coefficient (ADC) values derived from histogram analysis of the whole rectal cancer as a quantitative parameter to evaluate pathologic complete response (pCR) on preoperative magnetic resonance imaging (MRI). We enrolled a total of 86 consecutive patients who had undergone surgery for rectal cancer after neoadjuvant chemoradiotherapy (CRT) at our institution between July 2012 and November 2014. Two radiologists who were blinded to the final pathological results reviewed post-CRT MRI to evaluate tumor stage. Quantitative image analysis was performed using T2 -weighted and diffusion-weighted images independently by two radiologists using dedicated software that performed histogram analysis to assess the distribution of ADC in the whole tumor. After surgery, 16 patients were confirmed to have achieved pCR (18.6%). All parameters from pre- and post-CRT ADC histogram showed good or excellent agreement between two readers. The minimum, 10th, 25th, 50th, and 75th percentile and mean ADC from post-CRT ADC histogram were significantly higher in the pCR group than in the non-pCR group for both readers. The 25th percentile value from ADC histogram in post-CRT MRI had the best diagnostic performance for detecting pCR, with an area under the receiver operating characteristic curve of 0.796. Low percentile values derived from the ADC histogram analysis of rectal cancer on MRI after CRT showed a significant difference between pCR and non-pCR groups, demonstrating the utility of the ADC value as a quantitative and objective marker to evaluate complete pathologic response to preoperative CRT in rectal cancer. J. Magn. Reson. Imaging 2016;44:212-220. © 2015 Wiley Periodicals, Inc.

Non-parametric representation and prediction of single- and multi-shell diffusion-weighted MRI data using Gaussian processes

PubMed Central

Andersson, Jesper L.R.; Sotiropoulos, Stamatios N.

2015-01-01

Diffusion MRI offers great potential in studying the human brain microstructure and connectivity. However, diffusion images are marred by technical problems, such as image distortions and spurious signal loss. Correcting for these problems is non-trivial and relies on having a mechanism that predicts what to expect. In this paper we describe a novel way to represent and make predictions about diffusion MRI data. It is based on a Gaussian process on one or several spheres similar to the Geostatistical method of “Kriging”. We present a choice of covariance function that allows us to accurately predict the signal even from voxels with complex fibre patterns. For multi-shell data (multiple non-zero b-values) the covariance function extends across the shells which means that data from one shell is used when making predictions for another shell. PMID:26236030

Added Value of Assessing Adnexal Masses with Advanced MRI Techniques

PubMed Central

Thomassin-Naggara, I.; Balvay, D.; Rockall, A.; Carette, M. F.; Ballester, M.; Darai, E.; Bazot, M.

2015-01-01

This review will present the added value of perfusion and diffusion MR sequences to characterize adnexal masses. These two functional MR techniques are readily available in routine clinical practice. We will describe the acquisition parameters and a method of analysis to optimize their added value compared with conventional images. We will then propose a model of interpretation that combines the anatomical and morphological information from conventional MRI sequences with the functional information provided by perfusion and diffusion weighted sequences. PMID:26413542

3D Fast Spin Echo T2-weighted Contrast for Imaging the Female Cervix

NASA Astrophysics Data System (ADS)

Vargas Sanchez, Andrea Fernanda

Magnetic Resonance Imaging (MRI) with T2-weighted contrast is the preferred modality for treatment planning and monitoring of cervical cancer. Current clinical protocols image the volume of interest multiple times with two dimensional (2D) T2-weighted MRI techniques. It is of interest to replace these multiple 2D acquisitions with a single three dimensional (3D) MRI acquisition to save time. However, at present the image contrast of standard 3D MRI does not distinguish cervical healthy tissue from cancerous tissue. The purpose of this thesis is to better understand the underlying factors that govern the contrast of 3D MRI and exploit this understanding via sequence modifications to improve the contrast. Numerical simulations are developed to predict observed contrast alterations and to propose an improvement. Improvements of image contrast are shown in simulation and with healthy volunteers. Reported results are only preliminary but a promising start to establish definitively 3D MRI for cervical cancer applications.

Is 3-Tesla Gd-EOB-DTPA-Enhanced MRI with Diffusion-Weighted Imaging Superior to 64-Slice Contrast-Enhanced CT for the Diagnosis of Hepatocellular Carcinoma?

PubMed Central

Maiwald, Bettina; Lobsien, Donald; Kahn, Thomas; Stumpp, Patrick

2014-01-01

Objectives To compare 64-slice contrast-enhanced computed tomography (CT) with 3-Tesla magnetic resonance imaging (MRI) using Gd-EOB-DTPA for the diagnosis of hepatocellular carcinoma (HCC) and evaluate the utility of diffusion-weighted imaging (DWI) in this setting. Methods 3-phase-liver-CT was performed in fifty patients (42 male, 8 female) with suspected or proven HCC. The patients were subjected to a 3-Tesla-MRI-examination with Gd-EOB-DTPA and diffusion weighted imaging (DWI) at b-values of 0, 50 and 400 s/mm2. The apparent diffusion coefficient (ADC)-value was determined for each lesion detected in DWI. The histopathological report after resection or biopsy of a lesion served as the gold standard, and a surrogate of follow-up or complementary imaging techniques in combination with clinical and paraclinical parameters was used in unresected lesions. Diagnostic accuracy, sensitivity, specificity, and positive and negative predictive values were evaluated for each technique. Results MRI detected slightly more lesions that were considered suspicious for HCC per patient compared to CT (2.7 versus 2.3, respectively). ADC-measurements in HCC showed notably heterogeneous values with a median of 1.2±0.5×10−3 mm2/s (range from 0.07±0.1 to 3.0±0.1×10−3 mm2/s). MRI showed similar diagnostic accuracy, sensitivity, and positive and negative predictive values compared to CT (AUC 0.837, sensitivity 92%, PPV 80% and NPV 90% for MRI vs. AUC 0.798, sensitivity 85%, PPV 79% and NPV 82% for CT; not significant). Specificity was 75% for both techniques. Conclusions Our study did not show a statistically significant difference in detection in detection of HCC between MRI and CT. Gd-EOB-DTPA-enhanced MRI tended to detect more lesions per patient compared to contrast-enhanced CT; therefore, we would recommend this modality as the first-choice imaging method for the detection of HCC and therapeutic decisions. However, contrast-enhanced CT was not inferior in our study, so that it can be a useful image modality for follow-up examinations. PMID:25375778

Effect of gradient pulse duration on MRI estimation of the diffusional kurtosis for a two-compartment exchange model

NASA Astrophysics Data System (ADS)

Jensen, Jens H.; Helpern, Joseph A.

2011-06-01

Hardware constraints typically require the use of extended gradient pulse durations for clinical applications of diffusion-weighted magnetic resonance imaging (DW-MRI), which can potentially influence the estimation of diffusion metrics. Prior studies have examined this effect for the apparent diffusion coefficient. This study employs a two-compartment exchange model in order to assess the gradient pulse duration sensitivity of the apparent diffusional kurtosis (ADK), a quantitative index of diffusional non-Gaussianity. An analytic expression is derived and numerically evaluated for parameter ranges relevant to DW-MRI of brain. It is found that the ADK differs from the true diffusional kurtosis by at most a few percent. This suggests that ADK estimates for brain may be robust with respect to changes in pulse gradient duration.

Early detection of neuropathophysiology using diffusion-weighted magnetic resonance imaging in asymptomatic cats with feline immunodeficiency viral infection.

PubMed

Bucy, Daniel S; Brown, Mark S; Bielefeldt-Ohmann, Helle; Thompson, Jesse; Bachand, Annette M; Morges, Michelle; Elder, John H; Vandewoude, Sue; Kraft, Susan L

2011-08-01

HIV infection results in a highly prevalent syndrome of cognitive and motor disorders designated as HIV-associated dementia (HAD). Neurologic dysfunction resembling HAD has been documented in cats infected with strain PPR of the feline immunodeficiency virus (FIV), whereas another highly pathogenic strain (C36) has not been known to cause neurologic signs. Animals experimentally infected with equivalent doses of FIV-C36 or FIV-PPR, and uninfected controls were evaluated by magnetic resonance diffusion-weighted imaging (DW-MRI) and spectroscopy (MRS) at 17.5-18 weeks post-infection, as part of a study of viral clade pathogenesis in FIV-infected cats. The goals of the MR imaging portion of the project were to determine whether this methodology was capable of detecting early neuropathophysiology in the absence of outward manifestation of neurological signs and to compare the MR imaging results for the two viral strains expected to have differing degrees of neurologic effects. We hypothesized that there would be increased diffusion, evidenced by the apparent diffusion coefficient as measured by DW-MRI, and altered metabolite ratios measured by MRS, in the brains of FIV-PPR-infected cats relative to C36-infected cats and uninfected controls. Increased apparent diffusion coefficients were seen in the white matter, gray matter, and basal ganglia of both the PPR and C36-infected (asymptomatic) cats. Thalamic MRS metabolite ratios did not differ between groups. The equivalently increased diffusion by DW-MRI suggests similar indirect neurotoxicity mechanisms for the two viral genotypes. DW-MRI is a sensitive tool to detect neuropathophysiological changes in vivo that could be useful during longitudinal studies of FIV.

Brain structural changes in spasmodic dysphonia: A multimodal magnetic resonance imaging study.

PubMed

Kostic, Vladimir S; Agosta, Federica; Sarro, Lidia; Tomić, Aleksandra; Kresojević, Nikola; Galantucci, Sebastiano; Svetel, Marina; Valsasina, Paola; Filippi, Massimo

2016-04-01

The pathophysiology of spasmodic dysphonia is poorly understood. This study evaluated patterns of cortical morphology, basal ganglia, and white matter microstructural alterations in patients with spasmodic dysphonia relative to healthy controls. T1-weighted and diffusion tensor magnetic resonance imaging (MRI) scans were obtained from 13 spasmodic dysphonia patients and 30 controls. Tract-based spatial statistics was applied to compare diffusion tensor MRI indices (i.e., mean, radial and axial diffusivities, and fractional anisotropy) between groups on a voxel-by-voxel basis. Cortical measures were analyzed using surface-based morphometry. Basal ganglia were segmented on T1-weighted images, and volumes and diffusion tensor MRI metrics of nuclei were measured. Relative to controls, patients with spasmodic dysphonia showed increased cortical surface area of the primary somatosensory cortex bilaterally in a region consistent with the buccal sensory representation, as well as right primary motor cortex, left superior temporal, supramarginal and superior frontal gyri. A decreased cortical area was found in the rolandic operculum bilaterally, left superior/inferior parietal and lingual gyri, as well as in the right angular gyrus. Compared to controls, spasmodic dysphonia patients showed increased diffusivities and decreased fractional anisotropy of the corpus callosum and major white matter tracts, in the right hemisphere. Altered diffusion tensor MRI measures were found in the right caudate and putamen nuclei with no volumetric changes. Multi-level alterations in voice-controlling networks, that included regions devoted not only to sensorimotor integration, motor preparation and motor execution, but also processing of auditory and visual information during speech, might have a role in the pathophysiology of spasmodic dysphonia. Copyright © 2016 Elsevier Ltd. All rights reserved.

Appearances of colorectal hepatic metastases at diffusion-weighted MRI compared with histopathology: initial observations.

PubMed

Scurr, E D; Collins, D J; Temple, L; Karanjia, N; Leach, M O; Koh, D-M

2012-03-01

To describe the appearances of colorectal liver metastases on diffusion-weighted MRI (DW-MRI) and to compare these appearances with histopathology. 43 patients with colorectal liver metastases were evaluated using breath-hold DW-MRI (b-values 0, 150 and 500 s mm(-2)). The b=500 s mm(-2) DW-MRI were reviewed consensually for lesion size and appearance by two readers. 18/43 patients underwent surgery allowing radiological-pathological comparison. Tissue sections were reviewed by a pathologist, who classified metastases histologically as cellular, fibrotic, necrotic or mixed. The frequency of DW-MRI findings and histological features were compared using the χ(2) test. 84 metastases were found in 43 patients. On b=500 s mm(-2) DW-MRI, metastases showed three high signal intensity patterns: rim (55/84), uniform (23/84) and variegate (6/84). Of the 55 metastases showing rim pattern, 54 were >1 cm in diameter (p<0.01, χ(2) test). 25/84 metastases were surgically resected. Of these, 11/22 metastases >1 cm in diameter showed rim pattern and demonstrated central necrosis at histopathology (p=0.04, χ(2) test). No definite relationship was found between uniform and variegate patterns with histology. Rim high signal intensity was the most common appearance of colorectal liver metastases >1 cm diameter on DW-MRI at b-values of 500 s mm(-2), a finding attributable to central necrosis.

Diffusion-Weighted Magnetic Resonance Imaging to Evaluate Major Salivary Gland Function Before and After Radiotherapy

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

Dirix, Piet; Keyzer, Frederik de; Vandecaveye, Vincent

2008-08-01

Purpose: To evaluate diffusion-weighted (DW)-MRI as a noninvasive tool to investigate major salivary gland function before and after radiotherapy (RT) for head and neck cancer (HNC). Methods and Materials: DW-MRI was performed in 8 HNC patients before and after parotid-sparing RT (mean dose to the contralateral parotid gland <26 Gy). A DW sequence was performed once at rest and then repeated continuously during salivary stimulation. Apparent diffusion coefficient (ADC) maps for both parotid and submandibular glands were calculated. Findings were compared with salivary gland scintigraphy. Results: Before RT, the mean ADC value at rest was significantly lower in the parotidmore » than in the submandibular glands. During the first 5 min of stimulation, the ADC value of the salivary glands showed a decrease, followed by a steady increase until a peak ADC, significantly higher than the baseline value, was reached after a median of 17 min. The baseline ADC value at rest was significantly higher after RT than before RT in the nonspared salivary glands but not in the spared parotid glands. In the contralateral parotid glands, the same response was seen as before RT. This pattern was completely lost in the nonspared glands. These results corresponded with remaining or loss of salivary function, respectively, as confirmed by salivary gland scintigraphy. Conclusions: Diffusion-weighted-MRI allows noninvasive evaluation of functional changes in the major salivary glands after RT and is a promising tool for investigating radiation-induced xerostomia.« less

Progressing Toward a Cohesive Pediatric 18F-FDG PET/MR Protocol: Is Administration of Gadolinium Chelates Necessary?

PubMed

Klenk, Christopher; Gawande, Rakhee; Tran, Vy Thao; Leung, Jennifer Trinh; Chi, Kevin; Owen, Daniel; Luna-Fineman, Sandra; Sakamoto, Kathleen M; McMillan, Alex; Quon, Andy; Daldrup-Link, Heike E

2016-01-01

With the increasing availability of integrated PET/MR scanners, the utility and need for MR contrast agents for combined scans is questioned. The purpose of our study was to evaluate whether administration of gadolinium chelates is necessary for evaluation of pediatric tumors on (18)F-FDG PET/MR images. First, in 119 pediatric patients with primary and secondary tumors, we used 14 diagnostic criteria to compare the accuracy of several MR sequences: unenhanced T2-weighted fast spin-echo imaging; unenhanced diffusion-weighted imaging; and-before and after gadolinium chelate contrast enhancement-T1-weighted 3-dimensional spoiled gradient echo LAVA (liver acquisition with volume acquisition) imaging. Next, in a subset of 36 patients who had undergone (18)F-FDG PET within 3 wk of MRI, we fused the PET images with the unenhanced T2-weighted MR images (unenhanced (18)F-FDG PET/MRI) and the enhanced T1-weighted MR images (enhanced (18)F-FDG PET/MRI). Using the McNemar test, we compared the accuracy of the two types of fused images using the 14 diagnostic criteria. We also evaluated the concordance between (18)F-FDG avidity and gadolinium chelate enhancement. The standard of reference was histopathologic results, surgical notes, and follow-up imaging. There was no significant difference in diagnostic accuracy between the unenhanced and enhanced MR images. Accordingly, there was no significant difference in diagnostic accuracy between the unenhanced and enhanced (18)F-FDG PET/MR images. (18)F-FDG avidity and gadolinium chelate enhancement were concordant in 30 of the 36 patients and 106 of their 123 tumors. Gadolinium chelate administration is not necessary for accurate diagnostic characterization of most solid pediatric malignancies on (18)F-FDG PET/MR images, with the possible exception of focal liver lesions. © 2016 by the Society of Nuclear Medicine and Molecular Imaging, Inc.

Endometrial Stromal Sarcoma of the Uterus: Magnetic Resonance Imaging Findings Including Apparent Diffusion Coefficient Value and Its Correlation With Ki-67 Expression.

PubMed

Li, Hai Ming; Liu, Jia; Qiang, Jin Wei; Gu, Wei Yong; Zhang, Guo Fu; Ma, Feng Hua

2017-11-01

This study aimed to investigate the conventional magnetic resonance imaging (MRI) and diffusion-weighted imaging (DWI) features of endometrial stromal sarcoma (ESS) including a preliminary investigation of the correlation between the apparent diffusion coefficient (ADC) value and Ki-67 expression. The clinical and MRI data of 15 patients with ESS confirmed by surgery and pathology were analyzed retrospectively. The conventional MR morphological features, signal intensity on DWI, ADC value (n = 14), and clinicopathological marker Ki-67 (n = 13) were evaluated. Of 15 patients with ESS, 13 tumors were low-grade ESS (LGESS), and the remaining 2 were high-grade ESS (HGESS); 9 tumors were located in the myometrium, 5 were located in the endometrium and/or cervical canal, and 1 was located in extrauterine. Thirteen (87%) of 15 tumors showed a homo- or heterogeneous isointensity on T1-weighted imaging and a heterogeneous hyperintensity on T2-weighted imaging. The hypointense bands were observed in 11 tumors (73%) on T2-weighted imaging. The degenerations (cystic/necrosis/hemorrhage) were observed in 7 LGESS tumors and 2 HGESS tumors. The DWI hyperintensity was observed in 13 tumors (93%) and isointensity in remaining 1. The mean ADC value of the solid components in 14 ESSs was (1.05 ± 0.20) × 10mm/s. The contrast-enhanced MRI showed an obvious enhancement in 14 tumors (93%) (heterogeneous in 7 LGESSs and 2 HGESSs; homogeneous in 5 LGESSs). The ADC value was inversely correlated with the Ki-67 expression (r = -0.613, P = 0.026). Patients with ESS showed some characteristics on conventional MRI and DWI, and there was an inverse correlation between the ADC value and Ki-67 expression.

Diffusion-weighted-preparation (D-prep) MRI as a future extension of SPECT/CT based surgical planning for sentinel node procedures in the head and neck area?

PubMed

Buckle, Tessa; KleinJan, Gijs H; Engelen, Thijs; van den Berg, Nynke S; DeRuiter, Marco C; van der Heide, Uulke; Valdes Olmos, Renato A; Webb, Andrew; van Buchem, Mark A; Balm, Alfons J; van Leeuwen, Fijs W B

2016-09-01

Even when guided by SPECT/CT planning of nodal resection in the head-and-neck area is challenging due to the many critical anatomical structures present within the surgical field. In this study the potential of a (SPECT/)MRI-based surgical planning method was explored. Hereby MRI increases the identification of SNs within clustered lymph nodes (LNs) and vital structures located adjacent to the SN (such as cranial nerve branches). SPECT/CT and pathology reports from 100 head-and-neck melanoma and 40 oral cavity cancer patients were retrospectively assessed for SN locations in levels I-V and degree of nodal clustering. A diffusion-weighted-preparation magnetic resonance neurography (MRN) sequence was used in eight healthy volunteers to detect LNs and peripheral nerves. In 15% of patients clustered nodes were retrospectively shown to be present at the location where the SN was identified on SPECT/CT (level IIA: 37.2%, level IIB: 21.6% and level III: 15.5%). With MRN, improved LN delineation enabled discrimination of individual LNs within a cluster. Uniquely, this MRI technology also provided insight in LN distribution (23.2±4 LNs per subject) and size (range 21-372mm(3)), and enabled non-invasive assessment of anatomical variances in the location of the LNs and facial nerves. Diffusion-weighted-preparation MRN enabled improved delineation of LNs and their surrounding delicate anatomical structures in the areas that most often harbor SNs in the head-and-neck. Based on our findings a combined SPECT/MRI approach is envisioned for future surgical planning of complex SN resections in this region. Copyright © 2016 Elsevier Ltd. All rights reserved.

Diffusion MRI in early cancer therapeutic response assessment

PubMed Central

Galbán, C. J.; Hoff, B. A.; Chenevert, T. L.; Ross, B. D.

2016-01-01

Imaging biomarkers for the predictive assessment of treatment response in patients with cancer earlier than standard tumor volumetric metrics would provide new opportunities to individualize therapy. Diffusion-weighted MRI (DW-MRI), highly sensitive to microenvironmental alterations at the cellular level, has been evaluated extensively as a technique for the generation of quantitative and early imaging biomarkers of therapeutic response and clinical outcome. First demonstrated in a rodent tumor model, subsequent studies have shown that DW-MRI can be applied to many different solid tumors for the detection of changes in cellularity as measured indirectly by an increase in the apparent diffusion coefficient (ADC) of water molecules within the lesion. The introduction of quantitative DW-MRI into the treatment management of patients with cancer may aid physicians to individualize therapy, thereby minimizing unnecessary systemic toxicity associated with ineffective therapies, saving valuable time, reducing patient care costs and ultimately improving clinical outcome. This review covers the theoretical basis behind the application of DW-MRI to monitor therapeutic response in cancer, the analytical techniques used and the results obtained from various clinical studies that have demonstrated the efficacy of DW-MRI for the prediction of cancer treatment response. PMID:26773848

MRI Features in a Canine Model of Ischemic Stroke: Correlation between Lesion Volume and Neurobehavioral Status during the Subacute Stage

PubMed Central

Kang, Byeong-Teck; Jang, Dong-Pyo; Gu, Su-Hyun; Lee, Jong-Hwan; Jung, Dong-In; Lim, Chae-Young; Kim, Ha-Jung; Kim, Young-Bo; Kim, Hyung-Joong; Woo, Eung-Je; Cho, Zang-Hee; Park, Hee-Myung

2009-01-01

The purpose of this study was to evaluate the diagnostic value of magnetic resonance imaging (MRI) and assess the correlation between the volume of the ischemic lesion and neurobehavioral status during the subacute stage of ischemic stroke. Ischemic stroke was induced in 6 healthy laboratory beagles through permanent occlusion of the middle cerebral artery (MCAO). T2-weighted and fluid-attenuated inversion recovery (FLAIR) imaging, diffusion-weighted imaging (DWI), measurement of the apparent diffusion coefficient (ADC) ratio, and neurobehavioral evaluation were performed 3 times serially by using a 1.5-T MR system: before and 3 and 10 d after MCAO. Ischemic lesions demonstrated T2 hyperintensity, FLAIR hyperintensity, and DWI hyperintensity. The ADC ratio was decreased initially but then was increased at 10 d after MCAO. Ischemic lesion volumes on T2-weighted and FLAIR imaging were not significantly different from those on DWI. The lesion volume and neurobehavioral score showed strong correlation. Our results suggest that conventional MRI may be a reliable diagnostic tool during the subacute stage of canine ischemic stroke. PMID:19887030

Diagnostic performance of magnetic resonance imaging and 3D endoanal ultrasound in detection, staging and assessment post treatment, in anal cancer.

PubMed

Reginelli, Alfonso; Granata, Vincenza; Fusco, Roberta; Granata, Francesco; Rega, Daniela; Roberto, Luca; Pellino, Gianluca; Rotondo, Antonio; Selvaggi, Francesco; Izzo, Francesco; Petrillo, Antonella; Grassi, Roberto

2017-04-04

We compared Magnetic Resonance Imaging (MRI) and 3D Endoanal Ultrasound (EAUS) imaging performance to confirm anal carcinoma and to monitor treatment response.58 patients with anal cancer were retrospectively enrolled. All patients underwent clinical examination, anoscopic examination; EAUS and contrast-enhanced MRI study before and after treatment. Four radiologists evaluated the presence of lesions, using a 4-point confidence scale, features of the lesion and nodes on EAUS images, T1-weighted (T1-W), T2-weighted (T2-W) and diffusion-weighted images (DWI) signal intensity (SI), the apparent diffusion coefficient (ADC) map for nodes and lesion, as well as enhancement pattern during dynamic MRI were assessed.All lesions were detected by EAUS while MRI detected 93.1% of anal cancer. MRI showed a good correlation with EAUS, anoscopy and clinical examination. The residual tissue not showed significant difference in EAUS assessment and T2-W SI in pre and post treatment. We found significant difference in dynamic study, in SI of DWI, in ADC map and values among responder's patients in pre and post treatment. The neoplastic nodes were hypoecoic on EAUS, with hyperintense signal on T2-W sequences and hypointense signal on T1-W. The neoplastic nodes showed SI on DWI sequences and ADC value similar to anal cancer. We found significant difference in nodes status in pre and post therapy on DWI data.3D EAUS and MRI are accurate techniques in anal cancer staging, although EAUS is more accurate than MRI for T1 stage. MRI allows correct detection of neoplastic nodes and can properly stratify patients into responders or non responders.

Spurious group differences due to head motion in a diffusion MRI study

PubMed Central

Yendiki, Anastasia; Koldewyn, Kami; Kakunoori, Sita; Kanwisher, Nancy; Fischl, Bruce

2014-01-01

Diffusion-weighted MRI (DW-MRI) has become a popular imaging modality for probing the microstructural properties of white matter and comparing them between populations in vivo. However, the contrast in DW-MRI arises from the microscopic random motion of water molecules in brain tissues, which makes it particularly sensitive to macroscopic head motion. Although this has been known since the introduction of DW-MRI, most studies that use this modality for group comparisons do not report measures of head motion for each group and rely on registration-based correction methods that cannot eliminate the full effects of head motion on the DW-MRI contrast. In this work we use data from children with autism and typically developing children to investigate the effects of head motion on differences in anisotropy and diffusivity measures between groups. We show that group differences in head motion can induce group differences in DW-MRI measures, and that this is the case even when comparing groups that include control subjects only, where no anisotropy or diffusivity differences are expected. We also show that such effects can be more prominent in some white-matter pathways than others, and that they can be ameliorated by including motion as a nuisance regressor in the analyses. Our results demonstrate the importance of taking head motion into account in any population study where one group might exhibit more head motion than the other. PMID:24269273

Effects of b-value and number of gradient directions on diffusion MRI measures obtained with Q-ball imaging

NASA Astrophysics Data System (ADS)

Schilling, Kurt G.; Nath, Vishwesh; Blaber, Justin; Harrigan, Robert L.; Ding, Zhaohua; Anderson, Adam W.; Landman, Bennett A.

2017-02-01

High-angular-resolution diffusion-weighted imaging (HARDI) MRI acquisitions have become common for use with higher order models of diffusion. Despite successes in resolving complex fiber configurations and probing microstructural properties of brain tissue, there is no common consensus on the optimal b-value and number of diffusion directions to use for these HARDI methods. While this question has been addressed by analysis of the diffusion-weighted signal directly, it is unclear how this translates to the information and metrics derived from the HARDI models themselves. Using a high angular resolution data set acquired at a range of b-values, and repeated 11 times on a single subject, we study how the b-value and number of diffusion directions impacts the reproducibility and precision of metrics derived from Q-ball imaging, a popular HARDI technique. We find that Q-ball metrics associated with tissue microstructure and white matter fiber orientation are sensitive to both the number of diffusion directions and the spherical harmonic representation of the Q-ball, and often are biased when under sampled. These results can advise researchers on appropriate acquisition and processing schemes, particularly when it comes to optimizing the number of diffusion directions needed for metrics derived from Q-ball imaging.

Brain Tissue Compartment Density Estimated Using Diffusion-Weighted MRI Yields Tissue Parameters Consistent With Histology

PubMed Central

Sepehrband, Farshid; Clark, Kristi A.; Ullmann, Jeremy F.P.; Kurniawan, Nyoman D.; Leanage, Gayeshika; Reutens, David C.; Yang, Zhengyi

2015-01-01

We examined whether quantitative density measures of cerebral tissue consistent with histology can be obtained from diffusion magnetic resonance imaging (MRI). By incorporating prior knowledge of myelin and cell membrane densities, absolute tissue density values were estimated from relative intra-cellular and intra-neurite density values obtained from diffusion MRI. The NODDI (neurite orientation distribution and density imaging) technique, which can be applied clinically, was used. Myelin density estimates were compared with the results of electron and light microscopy in ex vivo mouse brain and with published density estimates in a healthy human brain. In ex vivo mouse brain, estimated myelin densities in different sub-regions of the mouse corpus callosum were almost identical to values obtained from electron microscopy (Diffusion MRI: 42±6%, 36±4% and 43±5%; electron microscopy: 41±10%, 36±8% and 44±12% in genu, body and splenium, respectively). In the human brain, good agreement was observed between estimated fiber density measurements and previously reported values based on electron microscopy. Estimated density values were unaffected by crossing fibers. PMID:26096639

MRI as a Translational Tool for the Study of Neonatal Stroke

PubMed Central

Dzietko, Mark; Wendland, Michael; Derugin, Nikita; Ferriero, Donna M.; Vexler, Zinaida S.

2013-01-01

More than half of neonatal stroke survivors have long-term sequelae, including seizures and neurological deficits. Although the immature brain has tremendous potential for recovery, mechanisms governing repair are essentially unexplored. We explored whether magnetic resonance imaging (MRI) early or late after transient middle cerebral arterial occlusion in 10-day-old (P10) rats can serve as an intermediate endpoint for long-term studies. Injured animals selected by diffusion-weighted MRI during middle cerebral arterial occlusion were scanned using T2-weighted MRI at P18 and P25 (injury volumes on MRI and histology were compared), or were subjected to contrast-enhanced MRI at P13 to characterize cerebral microcirculatory disturbances and blood-brain barrier leakage. Injury volume did not predict histological outcome at 2 weeks. Major reductions occurred by P18, with no further changes by P25. Cerebral perfusion was significantly reduced in the injured caudate but blood-brain barrier leakage was small. Therefore, conventional T2-weighted MRI performed during a subchronic injury phase predicts long-term histological outcome after experimental neonatal focal stroke. PMID:21670390

Accuracy of combined dynamic contrast-enhanced magnetic resonance imaging and diffusion-weighted imaging for breast cancer detection: a meta-analysis.

PubMed

Zhang, Li; Tang, Min; Min, Zhiqian; Lu, Jun; Lei, Xiaoyan; Zhang, Xiaoling

2016-06-01

Magnetic resonance imaging (MRI) is increasingly being used to examine patients with suspected breast cancer. To determine the diagnostic performance of combined dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and diffusion-weighted imaging (DWI) for breast cancer detection. A comprehensive search of the PUBMED, EMBASE, Web of Science, and Cochrane Library databases was performed up to September 2014. Statistical analysis included pooling of sensitivity and specificity, positive likelihood ratio (PLR), negative likelihood ratio (NLR), diagnostic odds ratio (DOR), and diagnostic accuracy using the summary receiver operating characteristic (SROC). All analyses were conducted using STATA (version 12.0), RevMan (version 5.2), and Meta-Disc 1.4 software programs. Fourteen studies were analyzed, which included a total of 1140 patients with 1276 breast lesions. The pooled sensitivity and specificity of combined DCE-MRI and DWI were 91.6% and 85.5%, respectively. The pooled sensitivity and specificity of DWI-MRI were 86.0% and 75.6%, respectively. The pooled sensitivity and specificity of DCE-MRI were 93.2% and 71.1%. The area under the SROC curve (AUC-SROC) of combined DCE-MRI and DWI was 0.94, the DCE-MRI of 0.85. Deeks testing confirmed no significant publication bias in all studies. Combined DCE-MRI and DWI had superior diagnostic accuracy than either DCE-MRI or DWI alone for the diagnosis of breast cancer. © The Foundation Acta Radiologica 2015.

Studying variability in human brain aging in a population-based German cohort-rationale and design of 1000BRAINS.

PubMed

Caspers, Svenja; Moebus, Susanne; Lux, Silke; Pundt, Noreen; Schütz, Holger; Mühleisen, Thomas W; Gras, Vincent; Eickhoff, Simon B; Romanzetti, Sandro; Stöcker, Tony; Stirnberg, Rüdiger; Kirlangic, Mehmet E; Minnerop, Martina; Pieperhoff, Peter; Mödder, Ulrich; Das, Samir; Evans, Alan C; Jöckel, Karl-Heinz; Erbel, Raimund; Cichon, Sven; Nöthen, Markus M; Sturma, Dieter; Bauer, Andreas; Jon Shah, N; Zilles, Karl; Amunts, Katrin

2014-01-01

The ongoing 1000 brains study (1000BRAINS) is an epidemiological and neuroscientific investigation of structural and functional variability in the human brain during aging. The two recruitment sources are the 10-year follow-up cohort of the German Heinz Nixdorf Recall (HNR) Study, and the HNR MultiGeneration Study cohort, which comprises spouses and offspring of HNR subjects. The HNR is a longitudinal epidemiological investigation of cardiovascular risk factors, with a comprehensive collection of clinical, laboratory, socioeconomic, and environmental data from population-based subjects aged 45-75 years on inclusion. HNR subjects underwent detailed assessments in 2000, 2006, and 2011, and completed annual postal questionnaires on health status. 1000BRAINS accesses these HNR data and applies a separate protocol comprising: neuropsychological tests of attention, memory, executive functions and language; examination of motor skills; ratings of personality, life quality, mood and daily activities; analysis of laboratory and genetic data; and state-of-the-art magnetic resonance imaging (MRI, 3 Tesla) of the brain. The latter includes (i) 3D-T1- and 3D-T2-weighted scans for structural analyses and myelin mapping; (ii) three diffusion imaging sequences optimized for diffusion tensor imaging, high-angular resolution diffusion imaging for detailed fiber tracking and for diffusion kurtosis imaging; (iii) resting-state and task-based functional MRI; and (iv) fluid-attenuated inversion recovery and MR angiography for the detection of vascular lesions and the mapping of white matter lesions. The unique design of 1000BRAINS allows: (i) comprehensive investigation of various influences including genetics, environment and health status on variability in brain structure and function during aging; and (ii) identification of the impact of selected influencing factors on specific cognitive subsystems and their anatomical correlates.

Multi-institutional validation of a novel textural analysis tool for preoperative stratification of suspected thyroid tumors on diffusion-weighted MRI.

PubMed

Brown, Anna M; Nagala, Sidhartha; McLean, Mary A; Lu, Yonggang; Scoffings, Daniel; Apte, Aditya; Gonen, Mithat; Stambuk, Hilda E; Shaha, Ashok R; Tuttle, R Michael; Deasy, Joseph O; Priest, Andrew N; Jani, Piyush; Shukla-Dave, Amita; Griffiths, John

2016-04-01

Ultrasound-guided fine needle aspirate cytology fails to diagnose many malignant thyroid nodules; consequently, patients may undergo diagnostic lobectomy. This study assessed whether textural analysis (TA) could noninvasively stratify thyroid nodules accurately using diffusion-weighted MRI (DW-MRI). This multi-institutional study examined 3T DW-MRI images obtained with spin echo echo planar imaging sequences. The training data set included 26 patients from Cambridge, United Kingdom, and the test data set included 18 thyroid cancer patients from Memorial Sloan Kettering Cancer Center (New York, New York, USA). Apparent diffusion coefficients (ADCs) were compared over regions of interest (ROIs) defined on thyroid nodules. TA, linear discriminant analysis (LDA), and feature reduction were performed using the 21 MaZda-generated texture parameters that best distinguished benign and malignant ROIs. Training data set mean ADC values were significantly different for benign and malignant nodules (P = 0.02) with a sensitivity and specificity of 70% and 63%, respectively, and a receiver operator characteristic (ROC) area under the curve (AUC) of 0.73. The LDA model of the top 21 textural features correctly classified 89/94 DW-MRI ROIs with 92% sensitivity, 96% specificity, and an AUC of 0.97. This algorithm correctly classified 16/18 (89%) patients in the independently obtained test set of thyroid DW-MRI scans. TA classifies thyroid nodules with high sensitivity and specificity on multi-institutional DW-MRI data sets. This method requires further validation in a larger prospective study. Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance. © 2015 The Authors. Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine.

Improved Performance in Differentiating Benign from Malignant Sinonasal Tumors Using Diffusion-weighted Combined with Dynamic Contrast-enhanced Magnetic Resonance Imaging

PubMed Central

Wang, Xin-Yan; Yan, Fei; Hao, Hui; Wu, Jian-Xing; Chen, Qing-Hua; Xian, Jun-Fang

2015-01-01

Background: Differentiating benign from malignant sinonsal lesions is essential for treatment planning as well as determining the patient's prognosis, but the differentiation is often difficult in clinical practice. The study aimed to determine whether the combination of diffusion-weighted (DW) and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) can improve the performance in differentiating benign from malignant sinonasal tumors. Methods: This retrospective study included 197 consecutive patients with sinonasal tumors (116 malignant tumors and 81 benign tumors). All patients underwent both DW and DCE-MRI in a 3-T magnetic resonance scanner. Two different settings of b values (0,700 and 0,1000 s/mm2) and two different strategies of region of interest (ROI) including whole slice (WS) and partial slice (PS) were used to calculate apparent diffusion coefficients (ADCs). A DW parameter with WS ADCsb0,1000 and two DCE-MRI parameters (time intensity curve [TIC] and time to peak enhancement [Tpeak]) were finally combined to use in differentiating the benign from the malignant tumors in this study. Results: The mean ADCs of malignant sinonasal tumors (WS ADCsb0,1000 = 1.084 × 10−3 mm2/s) were significantly lower than those of benign tumors (WS ADCsb0,1000 = 1.617 × 10−3 mm2/s, P < 0.001). The accuracy using WS ADCsb0,1000 alone was 83.7% in differentiating the benign from the malignant tumors (85.3% sensitivity, 81.2% specificity, 86.4% positive predictive value [PPV], and 79.5% negative predictive value [NPV]). The accuracy using DCE with Tpeak and TIC alone was 72.1% (69.1% sensitivity, 74.1% specificity, 77.5% PPV, and 65.1% NPV). Using DW-MRI parameter was superior than using DCE parameters in differentiation between benign and malignant sinonasal tumors (P < 0.001). The accuracy was 87.3% (90.5% sensitivity, 82.7% specificity, 88.2% PPV, and 85.9% NPV) using DW-MRI combined with DCE-MRI, which was superior than that using DCE-MRI alone or using DW-MRI alone (both P < 0.001) in differentiating the benign from the malignant tumors. Conclusions: Diffusion-weighted combined with DCE-MRI can improve imaging performance in differentiating benign from malignant sinonasal tumors, which has the potential to improve diagnostic accuracy and to provide added value in the management for these tumors. PMID:25698188

Interrogating two schedules of the AKT inhibitor MK-2206 in patients with advanced solid tumors incorporating novel pharmacodynamic and functional imaging biomarkers

PubMed Central

Yap, Timothy A.; Yan, Li; Patnaik, Amita; Tunariu, Nina; Biondo, Andrea; Fearen, Ivy; Papadopoulos, Kyriakos P.; Olmos, David; Baird, Richard; Delgado, Liliana; Tetteh, Ernestina; Beckman, Robert A.; Lupinacci, Lisa; Riisnaes, Ruth; Decordova, Shaun; Heaton, Simon P.; Swales, Karen; deSouza, Nandita M; Leach, Martin O.; Garrett, Michelle D.; Sullivan, Daniel M.; de Bono, Johann S.; Tolcher, Anthony W.

2014-01-01

Purpose Multiple cancers harbor genetic aberrations that impact AKT signaling. MK-2206 is a potent pan-AKT inhibitor with a maximum tolerated dose (MTD) previously established at 60mg on alternate days (QOD). Due to a long half-life (60-80h), a weekly (QW) MK-2206 schedule was pursued to compare intermittent QW and continuous QOD dosing. Experimental Design Patients with advanced cancers were enrolled onto a QW dose-escalation phase I study to investigate the safety and pharmacokinetic-pharmacodynamic profiles of tumor and platelet-rich plasma (PRP). The QOD MTD of MK-2206 was also assessed in patients with ovarian and castration-resistant prostate cancers, and patients with advanced cancers undergoing multiparametric functional magnetic resonance imaging (MRI) studies, including dynamic contrast-enhanced MRI, diffusion-weighted imaging, magnetic resonance spectroscopy and intrinsic susceptibility-weighted MRI. Results Seventy-one patients were enrolled; 38 patients had 60mg MK-2206 QOD, while 33 received MK-2206 at 90mg, 135mg, 150mg, 200mg, 250mg, and 300mg QW. The QW MK-2206 MTD was established at 200mg following dose-limiting rash at 250mg and 300mg. QW dosing appeared to be similarly tolerated to QOD, with toxicities including rash, gastrointestinal symptoms, fatigue, and hyperglycemia. Significant AKT pathway blockade was observed with both continuous QOD and intermittent QW dosing of MK-2206 in serially-obtained tumor and PRP specimens. The functional imaging studies demonstrated that complex multiparametric MRI protocols may be effectively implemented in a phase I trial. Conclusions MK-2206 safely results in significant AKT pathway blockade in QOD and QW schedules. The intermittent dose of 200mg QW is currently used in phase II MK-2206 monotherapy and combination studies. PMID:25239610

Interrogating two schedules of the AKT inhibitor MK-2206 in patients with advanced solid tumors incorporating novel pharmacodynamic and functional imaging biomarkers.

PubMed

Yap, Timothy A; Yan, Li; Patnaik, Amita; Tunariu, Nina; Biondo, Andrea; Fearen, Ivy; Papadopoulos, Kyriakos P; Olmos, David; Baird, Richard; Delgado, Liliana; Tetteh, Ernestina; Beckman, Robert A; Lupinacci, Lisa; Riisnaes, Ruth; Decordova, Shaun; Heaton, Simon P; Swales, Karen; deSouza, Nandita M; Leach, Martin O; Garrett, Michelle D; Sullivan, Daniel M; de Bono, Johann S; Tolcher, Anthony W

2014-11-15

Multiple cancers harbor genetic aberrations that impact AKT signaling. MK-2206 is a potent pan-AKT inhibitor with a maximum tolerated dose (MTD) previously established at 60 mg on alternate days (QOD). Due to a long half-life (60-80 hours), a weekly (QW) MK-2206 schedule was pursued to compare intermittent QW and continuous QOD dosing. Patients with advanced cancers were enrolled in a QW dose-escalation phase I study to investigate the safety and pharmacokinetic-pharmacodynamic profiles of tumor and platelet-rich plasma (PRP). The QOD MTD of MK-2206 was also assessed in patients with ovarian and castration-resistant prostate cancers and patients with advanced cancers undergoing multiparametric functional magnetic resonance imaging (MRI) studies, including dynamic contrast-enhanced MRI, diffusion-weighted imaging, magnetic resonance spectroscopy, and intrinsic susceptibility-weighted MRI. A total of 71 patients were enrolled; 38 patients had 60 mg MK-2206 QOD, whereas 33 received MK-2206 at 90, 135, 150, 200, 250, and 300 mg QW. The QW MK-2206 MTD was established at 200 mg following dose-limiting rash at 250 and 300 mg. QW dosing appeared to be similarly tolerated to QOD, with toxicities including rash, gastrointestinal symptoms, fatigue, and hyperglycemia. Significant AKT pathway blockade was observed with both continuous QOD and intermittent QW dosing of MK-2206 in serially obtained tumor and PRP specimens. The functional imaging studies demonstrated that complex multiparametric MRI protocols may be effectively implemented in a phase I trial. Treatment with MK-2206 safely results in significant AKT pathway blockade in QOD and QW schedules. The intermittent dose of 200 mg QW is currently used in phase II MK-2206 monotherapy and combination studies (NCT00670488). ©2014 American Association for Cancer Research.

Software Toolbox for Low-Frequency Conductivity and Current Density Imaging Using MRI.

PubMed

Sajib, Saurav Z K; Katoch, Nitish; Kim, Hyung Joong; Kwon, Oh In; Woo, Eung Je

2017-11-01

Low-frequency conductivity and current density imaging using MRI includes magnetic resonance electrical impedance tomography (MREIT), diffusion tensor MREIT (DT-MREIT), conductivity tensor imaging (CTI), and magnetic resonance current density imaging (MRCDI). MRCDI and MREIT provide current density and isotropic conductivity images, respectively, using current-injection phase MRI techniques. DT-MREIT produces anisotropic conductivity tensor images by incorporating diffusion weighted MRI into MREIT. These current-injection techniques are finding clinical applications in diagnostic imaging and also in transcranial direct current stimulation (tDCS), deep brain stimulation (DBS), and electroporation where treatment currents can function as imaging currents. To avoid adverse effects of nerve and muscle stimulations due to injected currents, conductivity tensor imaging (CTI) utilizes B1 mapping and multi-b diffusion weighted MRI to produce low-frequency anisotropic conductivity tensor images without injecting current. This paper describes numerical implementations of several key mathematical functions for conductivity and current density image reconstructions in MRCDI, MREIT, DT-MREIT, and CTI. To facilitate experimental studies of clinical applications, we developed a software toolbox for these low-frequency conductivity and current density imaging methods. This MR-based conductivity imaging (MRCI) toolbox includes 11 toolbox functions which can be used in the MATLAB environment. The MRCI toolbox is available at http://iirc.khu.ac.kr/software.html . Its functions were tested by using several experimental datasets, which are provided together with the toolbox. Users of the toolbox can focus on experimental designs and interpretations of reconstructed images instead of developing their own image reconstruction softwares. We expect more toolbox functions to be added from future research outcomes. Low-frequency conductivity and current density imaging using MRI includes magnetic resonance electrical impedance tomography (MREIT), diffusion tensor MREIT (DT-MREIT), conductivity tensor imaging (CTI), and magnetic resonance current density imaging (MRCDI). MRCDI and MREIT provide current density and isotropic conductivity images, respectively, using current-injection phase MRI techniques. DT-MREIT produces anisotropic conductivity tensor images by incorporating diffusion weighted MRI into MREIT. These current-injection techniques are finding clinical applications in diagnostic imaging and also in transcranial direct current stimulation (tDCS), deep brain stimulation (DBS), and electroporation where treatment currents can function as imaging currents. To avoid adverse effects of nerve and muscle stimulations due to injected currents, conductivity tensor imaging (CTI) utilizes B1 mapping and multi-b diffusion weighted MRI to produce low-frequency anisotropic conductivity tensor images without injecting current. This paper describes numerical implementations of several key mathematical functions for conductivity and current density image reconstructions in MRCDI, MREIT, DT-MREIT, and CTI. To facilitate experimental studies of clinical applications, we developed a software toolbox for these low-frequency conductivity and current density imaging methods. This MR-based conductivity imaging (MRCI) toolbox includes 11 toolbox functions which can be used in the MATLAB environment. The MRCI toolbox is available at http://iirc.khu.ac.kr/software.html . Its functions were tested by using several experimental datasets, which are provided together with the toolbox. Users of the toolbox can focus on experimental designs and interpretations of reconstructed images instead of developing their own image reconstruction softwares. We expect more toolbox functions to be added from future research outcomes.

Diffusion-weighted magnetic resonance imaging in autoimmune pancreatitis.

PubMed

Taniguchi, Takao; Kobayashi, Hisato; Nishikawa, Koji; Iida, Etsushi; Michigami, Yoshihiro; Morimoto, Emiko; Yamashita, Rikiya; Miyagi, Ken; Okamoto, Motozumi

2009-04-01

The aim of this study was to investigate the usefulness of diffusion-weighted magnetic resonance imaging (DWI MRI) for the diagnosis and evaluation of autoimmune pancreatitis (AIP). A total of 4 consecutive patients with AIP, 5 patients with chronic alcoholic pancreatitis (CP), and 13 patients without pancreatic disease (controls) were studied. DWI was performed in the axial plane with spin-echo echo-planar imaging single-shot sequence. Apparent diffusion coefficients (ADCs) were measured in circular regions of interest in the pancreas. In AIP patients, abdominal MRI was performed before, and 2-4 weeks after steroid treatment. Follow-up study was performed chronologically for up to 11 months in two patients. The correlation between ADCs of the pancreas and the immunoglobulin G4 (IgG4) index (serum IgG4 value/serum IgG4 value before steroid treatment) was evaluated. In the AIP patients, DWI of the pancreas showed high signal intensity, and the ADCs of the pancreas (mean +/- SD: 0.97 +/- 0.18 x 10(-3) mm(2)/s) were significantly lower than those in patients with CP (1.45 +/- 0.10 x 10(-3) mm(2)/s) or the controls (1.45 +/- 0.16 x 10(-3) mm(2)/s) (Mann-Whitney U-test, P < 0.05). In one AIP patient with focal swelling of the pancreas head that appeared to be a mass, DWI showed high signal intensity throughout the pancreas, indicating diffuse involvement. The ADCs of the pancreas and IgG4 index were significantly inversely correlated (Spearman's rank correlation coefficient, r (s) = -0.80, P < 0.05). Autoimmune pancreatitis showed high signal intensity on DWI, which improved after steroid treatment. ADCs reflected disease activity. Thus, diffusion-weighted MRI might be useful for diagnosing AIP, determining the affected area, and evaluating the effect of treatment.

Diffusion-Weighted MRI Assessment of Adjacent Disc Degeneration After Thoracolumbar Vertebral Fractures

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

Noriega, David C., E-mail: dcnoriega1970@gmail.com; Marcia, Stefano, E-mail: stemarcia@gmail.com; Ardura, Francisco, E-mail: fardura@ono.com

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 themore » 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.« less

Analysis of the contribution of experimental bias, experimental noise, and inter-subject biological variability on the assessment of developmental trajectories in diffusion MRI studies of the brain.

PubMed

Sadeghi, Neda; Nayak, Amritha; Walker, Lindsay; Okan Irfanoglu, M; Albert, Paul S; Pierpaoli, Carlo

2015-04-01

Metrics derived from the diffusion tensor, such as fractional anisotropy (FA) and mean diffusivity (MD) have been used in many studies of postnatal brain development. A common finding of previous studies is that these tensor-derived measures vary widely even in healthy populations. This variability can be due to inherent inter-individual biological differences as well as experimental noise. Moreover, when comparing different studies, additional variability can be introduced by different acquisition protocols. In this study we examined scans of 61 individuals (aged 4-22 years) from the NIH MRI study of normal brain development. Two scans were collected with different protocols (low and high resolution). Our goal was to separate the contributions of biological variability and experimental noise to the overall measured variance, as well as to assess potential systematic effects related to the use of different protocols. We analyzed FA and MD in seventeen regions of interest. We found that biological variability for both FA and MD varies widely across brain regions; biological variability is highest for FA in the lateral part of the splenium and body of the corpus callosum along with the cingulum and the superior longitudinal fasciculus, and for MD in the optic radiations and the lateral part of the splenium. These regions with high inter-individual biological variability are the most likely candidates for assessing genetic and environmental effects in the developing brain. With respect to protocol-related effects, the lower resolution acquisition resulted in higher MD and lower FA values for the majority of regions compared with the higher resolution protocol. However, the majority of the regions did not show any age-protocol interaction, indicating similar trajectories were obtained irrespective of the protocol used. Published by Elsevier Inc.

MRI signal intensity of anterior cruciate ligament graft after transtibial versus anteromedial portal technique (TRANSIG): design of a randomized controlled clinical trial.

PubMed

Ruiter, Simeon J S; Brouwer, Reinoud W; Meys, Tim W G M; Slump, Cornelis H; van Raay, Jos J A M

2016-08-10

There are two primary surgical techniques to reconstruct the anterior cruciate ligament (ACL), transtibial (TT) technique and anteromedial portal (AMP) technique. Currently, there is no consensus which surgical technique elicits the best clinical and functional outcomes. MRI-derived measures of the signal intensity (SI) of the ACL graft have been described as an independent predictor of graft properties. The purpose of this study is to compare the MRI derived SI measurements of the ACL graft one year after ACL reconstruction, in order to compare the outcomes of both the AMP and TT ACL reconstruction technique. Thirty-six patients will be included in a randomized controlled trial. Patients who are admitted for primary unilateral ACL reconstruction will be included in the study. Exclusion criteria are a history of previous surgery on the ipsilateral knee, re-rupture of the ipsilateral ACL graft, associated ligamentous injuries or meniscal tear of the ipsilateral knee, unhealthy contralateral knee, contra-indications for MRI and a preference for one of the two surgical techniques and/or orthopaedic surgeon. Primary outcome is MRI Signal intensity ratio (SIR) of the ACL graft. Secondary outcome measures are the International Knee Documentation Committee (IKDC) Knee Examination Form,the Knee injury and Osteoarthritis Outcome Scores (KOOS) and the Anterior Cruciate Ligament OsteoArthritis Score (ACLOAS). Differences between MRI SIR assessment with the current MRI protocol (proton density weighted imaging protocol) and the additional T2*-weighted gradient-echo protocol will be assessed. There is no consensus regarding the TT or AMP ACL reconstruction technique. SI measurements with MRI have been used in other clinical studies for evaluation of the ACL graft and maturation after ACL reconstruction compared to clinical and functional outcomes. This randomized controlled trial has been designed to compare the TT technique with the AMP technique with the use of MRI SI of the graft after ACL reconstruction. Netherlands Trial Registry NTR5410 (registered on August 24, 2015).

Multiparametric [18F]Fluorodeoxyglucose/ [18F]Fluoromisonidazole Positron Emission Tomography/ Magnetic Resonance Imaging of Locally Advanced Cervical Cancer for the Non-Invasive Detection of Tumor Heterogeneity: A Pilot Study

PubMed Central

Andrzejewski, Piotr; Baltzer, Pascal; Polanec, Stephan H.; Sturdza, Alina; Georg, Dietmar; Helbich, Thomas H.; Karanikas, Georgios; Grimm, Christoph; Polterauer, Stephan; Poetter, Richard; Wadsak, Wolfgang; Mitterhauser, Markus; Georg, Petra

2016-01-01

Objectives To investigate fused multiparametric positron emission tomography/magnetic resonance imaging (MP PET/MRI) at 3T in patients with locally advanced cervical cancer, using high-resolution T2-weighted, contrast-enhanced MRI (CE-MRI), diffusion-weighted imaging (DWI), and the radiotracers [18F]fluorodeoxyglucose ([18F]FDG) and [18F]fluoromisonidazol ([18F]FMISO) for the non-invasive detection of tumor heterogeneity for an improved planning of chemo-radiation therapy (CRT). Materials and Methods Sixteen patients with locally advanced cervix were enrolled in this IRB approved and were examined with fused MP [18F]FDG/ [18F]FMISO PET/MRI and in eleven patients complete data sets were acquired. MP PET/MRI was assessed for tumor volume, enhancement (EH)-kinetics, diffusivity, and [18F]FDG/ [18F]FMISO-avidity. Descriptive statistics and voxel-by-voxel analysis of MRI and PET parameters were performed. Correlations were assessed using multiple correlation analysis. Results All tumors displayed imaging parameters concordant with cervix cancer, i.e. type II/III EH-kinetics, restricted diffusivity (median ADC 0.80x10-3mm2/sec), [18F]FDG- (median SUVmax16.2) and [18F]FMISO-avidity (median SUVmax3.1). In all patients, [18F]FMISO PET identified the hypoxic tumor subvolume, which was independent of tumor volume. A voxel-by-voxel analysis revealed only weak correlations between the MRI and PET parameters (0.05–0.22), indicating that each individual parameter yields independent information and the presence of tumor heterogeneity. Conclusion MP [18F]FDG/ [18F]FMISO PET/MRI in patients with cervical cancer facilitates the acquisition of independent predictive and prognostic imaging parameters. MP [18F]FDG/ [18F]FMISO PET/MRI enables insights into tumor biology on multiple levels and provides information on tumor heterogeneity, which has the potential to improve the planning of CRT. PMID:27167829

Multiparametric [18F]Fluorodeoxyglucose/ [18F]Fluoromisonidazole Positron Emission Tomography/ Magnetic Resonance Imaging of Locally Advanced Cervical Cancer for the Non-Invasive Detection of Tumor Heterogeneity: A Pilot Study.

PubMed

Pinker, Katja; Andrzejewski, Piotr; Baltzer, Pascal; Polanec, Stephan H; Sturdza, Alina; Georg, Dietmar; Helbich, Thomas H; Karanikas, Georgios; Grimm, Christoph; Polterauer, Stephan; Poetter, Richard; Wadsak, Wolfgang; Mitterhauser, Markus; Georg, Petra

2016-01-01

To investigate fused multiparametric positron emission tomography/magnetic resonance imaging (MP PET/MRI) at 3T in patients with locally advanced cervical cancer, using high-resolution T2-weighted, contrast-enhanced MRI (CE-MRI), diffusion-weighted imaging (DWI), and the radiotracers [18F]fluorodeoxyglucose ([18F]FDG) and [18F]fluoromisonidazol ([18F]FMISO) for the non-invasive detection of tumor heterogeneity for an improved planning of chemo-radiation therapy (CRT). Sixteen patients with locally advanced cervix were enrolled in this IRB approved and were examined with fused MP [18F]FDG/ [18F]FMISO PET/MRI and in eleven patients complete data sets were acquired. MP PET/MRI was assessed for tumor volume, enhancement (EH)-kinetics, diffusivity, and [18F]FDG/ [18F]FMISO-avidity. Descriptive statistics and voxel-by-voxel analysis of MRI and PET parameters were performed. Correlations were assessed using multiple correlation analysis. All tumors displayed imaging parameters concordant with cervix cancer, i.e. type II/III EH-kinetics, restricted diffusivity (median ADC 0.80x10-3mm2/sec), [18F]FDG- (median SUVmax16.2) and [18F]FMISO-avidity (median SUVmax3.1). In all patients, [18F]FMISO PET identified the hypoxic tumor subvolume, which was independent of tumor volume. A voxel-by-voxel analysis revealed only weak correlations between the MRI and PET parameters (0.05-0.22), indicating that each individual parameter yields independent information and the presence of tumor heterogeneity. MP [18F]FDG/ [18F]FMISO PET/MRI in patients with cervical cancer facilitates the acquisition of independent predictive and prognostic imaging parameters. MP [18F]FDG/ [18F]FMISO PET/MRI enables insights into tumor biology on multiple levels and provides information on tumor heterogeneity, which has the potential to improve the planning of CRT.

Non-invasive imaging using reporter genes altering cellular water permeability

NASA Astrophysics Data System (ADS)

Mukherjee, Arnab; Wu, Di; Davis, Hunter C.; Shapiro, Mikhail G.

2016-12-01

Non-invasive imaging of gene expression in live, optically opaque animals is important for multiple applications, including monitoring of genetic circuits and tracking of cell-based therapeutics. Magnetic resonance imaging (MRI) could enable such monitoring with high spatiotemporal resolution. However, existing MRI reporter genes based on metalloproteins or chemical exchange probes are limited by their reliance on metals or relatively low sensitivity. Here we introduce a new class of MRI reporters based on the human water channel aquaporin 1. We show that aquaporin overexpression produces contrast in diffusion-weighted MRI by increasing tissue water diffusivity without affecting viability. Low aquaporin levels or mixed populations comprising as few as 10% aquaporin-expressing cells are sufficient to produce MRI contrast. We characterize this new contrast mechanism through experiments and simulations, and demonstrate its utility in vivo by imaging gene expression in tumours. Our results establish an alternative class of sensitive, metal-free reporter genes for non-invasive imaging.

Cerebral Metastases of Lung Cancer Mimicking Multiple Ischaemic Lesions - A Case Report and Review of Literature.

PubMed

Zacharzewska-Gondek, Anna; Maksymowicz, Hanna; Szymczyk, Małgorzata; Sąsiadek, Marek; Bladowska, Joanna

2017-01-01

Restricted diffusion that is found on magnetic resonance diffusion-weighted imaging (DWI) typically indicates acute ischaemic stroke. However, restricted diffusion can also occur in other diseases, like metastatic brain tumours, which we describe in this case report. A 57-year-old male, with a diagnosis of small-cell cancer of the right lung (microcellular anaplastic carcinoma), was admitted with focal neurological symptoms. Initial brain MRI revealed multiple, disseminated lesions that were hyperintense on T2-weighted images and did not enhance after contrast administration; notably, some lesions manifested restricted diffusion on DWI images. Based on these findings, disseminated ischaemic lesions were diagnosed. On follow-up MRI that was performed after 2 weeks, we observed enlargement of the lesions; there were multiple, disseminated, sharply outlined, contrast-enhancing, oval foci with persistent restriction of diffusion. We diagnosed the lesions as disseminated brain metastases due to lung cancer. To our knowledge, this is the first description of a patient with brain metastases that were characterised by restricted diffusion and no contrast enhancement. Multiple, disseminated brain lesions, that are characterised by restricted diffusion on DWI, typically indicate acute or hyperacute ischemic infarcts; however, they can also be due to hypercellular metastases, even if no contrast enhancement is observed. This latter possibility should be considered particularly in patients with cancer.

Appearances of colorectal hepatic metastases at diffusion-weighted MRI compared with histopathology: initial observations

PubMed Central

Scurr, E D; Collins, D J; Temple, L; Karanjia, N; Leach, M O; Koh, D-M

2012-01-01

Objective To describe the appearances of colorectal liver metastases on diffusion-weighted MRI (DW-MRI) and to compare these appearances with histopathology. Methods 43 patients with colorectal liver metastases were evaluated using breath-hold DW-MRI (b-values 0, 150 and 500 s mm–2). The b=500 s mm–2 DW-MRI were reviewed consensually for lesion size and appearance by two readers. 18/43 patients underwent surgery allowing radiological–pathological comparison. Tissue sections were reviewed by a pathologist, who classified metastases histologically as cellular, fibrotic, necrotic or mixed. The frequency of DW-MRI findings and histological features were compared using the χ2 test. Results 84 metastases were found in 43 patients. On b=500 s mm–2 DW-MRI, metastases showed three high signal intensity patterns: rim (55/84), uniform (23/84) and variegate (6/84). Of the 55 metastases showing rim pattern, 54 were >1 cm in diameter (p<0.01, χ2 test). 25/84 metastases were surgically resected. Of these, 11/22 metastases >1 cm in diameter showed rim pattern and demonstrated central necrosis at histopathology (p=0.04, χ2 test). No definite relationship was found between uniform and variegate patterns with histology. Conclusion Rim high signal intensity was the most common appearance of colorectal liver metastases >1 cm diameter on DW-MRI at b-values of 500 s mm–2, a finding attributable to central necrosis. PMID:21224302

Noninvasive Localization of Prostate Cancer via Diffusion Sensitive MRI

DTIC Science & Technology

2008-03-01

sequence, Haker et al and Roebuck et al using a line-scan diffusion sequence, and Vigneron et al using a fast spin-echo diffusion sequence (33,35-37...Mulkern RV, Haker S, Zhang J, Zou KH, Maier SE, Tempany CM. Detection of prostate cancer by integration of line-scan diffusion, T2-mapping and T2-weighted...36. Haker SJ, Szot Barnes A, Maier SE, Tempany CM, Mulkern RV. Diffusion Tensor Imaging for Prostate Cancer Detection: Preliminary Results from a

Primary Uterine Peripheral T-cell Lymphoma

PubMed Central

Gong, Jing; Dong, Aisheng; Wang, Yang; Zhang, Xuefeng; Yang, Panpan; Wang, Li; Jing, Wei

2016-01-01

Abstract Primary uterine non-Hodgkin's lymphoma is extremely rare accounting for <1% of all extranodal non-Hodgkin's lymphomas. Imaging findings of primary uterine lymphoma have rarely been reported before. We present magnetic resonance imaging (MRI) and fluorine-18-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET)/CT findings in a patient with primary uterine peripheral T-cell lymphoma. A 27-year-old female presented with intermittent fever with neutropenia for 7 months. MRI showed an ill-defined mass involved both the uterine corpus and cervix, resulting in diffuse enlargement of the uterus. This mass showed inhomogeneous hypointensity on unenhanced T1-weighted images, hyperintensity on diffusion-weighted imaging, relative hypointensity compared to the surrounding myometrium on T2-weighted images and lower enhancement than the surrounding myometrium on enhanced T1-weighted images. FDG PET/CT showed intense FDG uptake in the thickened wall of the uterine corpus and cervix with SUVmax of 26.9. There were multiple hypermetabolic lymph nodes in the pelvis and retroperitoneum. Uterine curettage and CT-guided biopsy of the uterine mass revealed peripheral T-cell lymphoma. Bone marrow biopsy revealed no evidence of lymphomatous involvement. The imaging and pathologic findings were consistent with primary uterine lymphoma. After 3 circles of chemotherapy, follow-up enhanced MRI showed decreased thickness of the uterine wall. Despite its rarity, primary uterine non-Hodgkin's lymphoma should be taken into consideration when a uterine tumor shows large size, relative hypointesity on both T2-weighted images and enhanced T1-weighted images compared to the surrounding myometrium, and intense FDG uptake on PET/CT. MRI may be helpful for describing the relationship between the tumor and adjacent structures. FDG PET/CT may be useful for tumor detection and staging. PMID:27124063

[Correlations between apparent diffusion coefficient in diffusion?weighted magnetic resonance imaging and molecular subtypes of invasive breast cancer masses].

PubMed

Shang, Liu-Tong; Yang, Jia-Fei; Lu, Jing; Wang, Ting-Ting; Zhou, Ying; Xing, Xin-Bo; Wang, Xin-Kun; Yang, Shu-Hui; Hu, Ming-Yan

2017-10-20

To study the correlation of apparent diffusion coefficient (ADC) measured by diffusion-weighted magnetic resonance imaging (MRI) with the molecular subtypes and biological prognostic factors of invasive breast cancer masses. Breast MRI data (including dynamic enhanced and diffusion-weighted imaging) were collected from 64 patients with pathologically confirmed invasive breast cancer masses (a total of 69 lesions). The mean ADC values of the lesions were calculated and their correlations were analyzed with the 5 molecular subtypes of invasive breast cancer and the biological prognostic factors including estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor 2 (HER2), and Ki-67 index. The ADC values did not differ significantly among the 5 molecular subtypes of invasive breast cancer masses (P>0.05) or among lesions with different ER, PR, or HER2 status (P>0.05). The mean ADC values were significantly higher in Ki-67-positive lesions than in the negative lesions (P=0.023 and negatively correlated with the expressions of Ki-67 (r=-0.249). ADC value can not be used to identify the molecular subtypes of invasive breast cancer masses or to evaluate the biological prognosis of the lesions, but its correlation with Ki-67 expression may help in prognostic evaluation and guiding clinical therapy of the tumors.

Corticobulbar tract changes as predictors of dysarthria in childhood brain injury.

PubMed

Liégeois, Frédérique; Tournier, Jacques-Donald; Pigdon, Lauren; Connelly, Alan; Morgan, Angela T

2013-03-05

To identify corticobulbar tract changes that may predict chronic dysarthria in young people who have sustained a traumatic brain injury (TBI) in childhood using diffusion MRI tractography. We collected diffusion-weighted MRI data from 49 participants. We compared 17 young people (mean age 17 years, 10 months; on average 8 years postinjury) with chronic dysarthria who sustained a TBI in childhood (range 3-16 years) with 2 control groups matched for age and sex: 1 group of young people who sustained a traumatic injury but had no subsequent dysarthria (n = 15), and 1 group of typically developing individuals (n = 17). We performed tractography from spherical seed regions within the precentral gyrus white matter to track: 1) the hand-related corticospinal tract; 2) the dorsal corticobulbar tract, thought to correspond to the lips/larynx motor representation; and 3) the ventral corticobulbar tract, corresponding to the tongue representation. Despite widespread white matter damage, radial (perpendicular) diffusivity within the left dorsal corticobulbar tract was the best predictor of the presence of dysarthria after TBI. Diffusion metrics in this tract also predicted speech and oromotor performance across the whole group of TBI participants, with additional significant contributions from ventral speech tract volume in the right hemisphere. An intact left dorsal corticobulbar tract seems crucial to the normal execution of speech long term after acquired injury. Examining the speech-related motor pathways using diffusion-weighted MRI tractography offers a promising prognostic tool for people with acquired, developmental, or degenerative neurologic conditions likely to affect speech.

Automated correction of improperly rotated diffusion gradient orientations in diffusion weighted MRI.

PubMed

Jeurissen, Ben; Leemans, Alexander; Sijbers, Jan

2014-10-01

Ensuring one is using the correct gradient orientations in a diffusion MRI study can be a challenging task. As different scanners, file formats and processing tools use different coordinate frame conventions, in practice, users can end up with improperly oriented gradient orientations. Using such wrongly oriented gradient orientations for subsequent diffusion parameter estimation will invalidate all rotationally variant parameters and fiber tractography results. While large misalignments can be detected by visual inspection, small rotations of the gradient table (e.g. due to angulation of the acquisition plane), are much more difficult to detect. In this work, we propose an automated method to align the coordinate frame of the gradient orientations with that of the corresponding diffusion weighted images, using a metric based on whole brain fiber tractography. By transforming the gradient table and measuring the average fiber trajectory length, we search for the transformation that results in the best global 'connectivity'. To ensure a fast calculation of the metric we included a range of algorithmic optimizations in our tractography routine. To make the optimization routine robust to spurious local maxima, we use a stochastic optimization routine that selects a random set of seed points on each evaluation. Using simulations, we show that our method can recover the correct gradient orientations with high accuracy and precision. In addition, we demonstrate that our technique can successfully recover rotated gradient tables on a wide range of clinically realistic data sets. As such, our method provides a practical and robust solution to an often overlooked pitfall in the processing of diffusion MRI. Copyright © 2014 Elsevier B.V. All rights reserved.

Prospective comparison of magnetic resonance imaging to transient elastography and serum markers for liver fibrosis detection.

PubMed

Dyvorne, Hadrien A; Jajamovich, Guido H; Bane, Octavia; Fiel, M Isabel; Chou, Hsin; Schiano, Thomas D; Dieterich, Douglas; Babb, James S; Friedman, Scott L; Taouli, Bachir

2016-05-01

Establishing accurate non-invasive methods of liver fibrosis quantification remains a major unmet need. Here, we assessed the diagnostic value of a multiparametric magnetic resonance imaging (MRI) protocol including diffusion-weighted imaging (DWI), dynamic contrast-enhanced (DCE)-MRI and magnetic resonance elastography (MRE) in comparison with transient elastography (TE) and blood tests [including ELF (Enhanced Liver Fibrosis) and APRI] for liver fibrosis detection. In this single centre cross-sectional study, we prospectively enrolled 60 subjects with liver disease who underwent multiparametric MRI (DWI, DCE-MRI and MRE), TE and blood tests. Correlation was assessed between non-invasive modalities and histopathologic findings including stage, grade and collagen content, while accounting for covariates such as age, sex, BMI, HCV status and MRI-derived fat and iron content. ROC curve analysis evaluated the performance of each technique for detection of moderate-to-advanced liver fibrosis (F2-F4) and advanced fibrosis (F3-F4). Magnetic resonance elastography provided the strongest correlation with fibrosis stage (r = 0.66, P < 0.001), inflammation grade (r = 0.52, P < 0.001) and collagen content (r = 0.53, P = 0.036). For detection of moderate-to-advanced fibrosis (F2-F4), AUCs were 0.78, 0.82, 0.72, 0.79, 0.71 for MRE, TE, DCE-MRI, DWI and APRI, respectively. For detection of advanced fibrosis (F3-F4), AUCs were 0.94, 0.77, 0.79, 0.79 and 0.70, respectively. Magnetic resonance elastography provides the highest correlation with histopathologic markers and yields high diagnostic performance for detection of advanced liver fibrosis and cirrhosis, compared to DWI, DCE-MRI, TE and serum markers. © 2016 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Temporal and spatial profile of brain diffusion-weighted MRI after cardiac arrest

PubMed Central

Mlynash, M.; Campbell, D.M.; Leproust, E.M.; Fischbein, N.J.; Bammer, R.; Eyngorn, I.; Hsia, A.W.; Moseley, M.; Wijman, C.A.C.

2010-01-01

Background and Purpose Diffusion-weighted MRI (DWI) of the brain is a promising technique to help predict functional outcome in comatose survivors of cardiac arrest. We aimed to evaluate prospectively the temporal-spatial profile of brain apparent diffusion coefficient (ADC) changes in comatose survivors during the first 8 days after cardiac arrest. Methods ADC values were measured by two independent and blinded investigators in predefined brain regions in 18 good and 15 poor outcome patients with 38 brain MRIs, and compared with 14 normal controls. The same brain regions were also assessed qualitatively by two other independent and blinded investigators. Results In poor outcome patients, cortical structures, in particular the occipital and temporal lobes, and the putamen exhibited the most profound ADC reductions, which were noted as early as 1.5 days and reached nadir between 3 to 5 days after the arrest. Conversely, when compared to normal controls, good outcome patients exhibited increased diffusivity, in particular in the hippocampus, temporal and occipital lobes, and corona radiata. By the qualitative MRI readings, one or more cortical gray matter structures were read as moderately-to-severely abnormal in all poor outcome patients imaged beyond 54 hours after the arrest, but not in the three patients imaged earlier. Conclusions Brain DWI changes in comatose post-cardiac arrest survivors in the first week after the arrest are region- and time-dependent and differ between good and poor outcome patients. With the increasing use of MRI in this context, it is important to be aware of these relationships. PMID:20595666

A Sparse Bayesian Learning Algorithm for White Matter Parameter Estimation from Compressed Multi-shell Diffusion MRI.

PubMed

Pisharady, Pramod Kumar; Sotiropoulos, Stamatios N; Sapiro, Guillermo; Lenglet, Christophe

2017-09-01

We propose a sparse Bayesian learning algorithm for improved estimation of white matter fiber parameters from compressed (under-sampled q-space) multi-shell diffusion MRI data. The multi-shell data is represented in a dictionary form using a non-monoexponential decay model of diffusion, based on continuous gamma distribution of diffusivities. The fiber volume fractions with predefined orientations, which are the unknown parameters, form the dictionary weights. These unknown parameters are estimated with a linear un-mixing framework, using a sparse Bayesian learning algorithm. A localized learning of hyperparameters at each voxel and for each possible fiber orientations improves the parameter estimation. Our experiments using synthetic data from the ISBI 2012 HARDI reconstruction challenge and in-vivo data from the Human Connectome Project demonstrate the improvements.

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

PubMed

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.

Local texture descriptors for the assessment of differences in diffusion magnetic resonance imaging of the brain.

PubMed

Thomsen, Felix Sebastian Leo; Delrieux, Claudio Augusto; de Luis-García, Rodrigo

2017-03-01

Descriptors extracted from magnetic resonance imaging (MRI) of the brain can be employed to locate and characterize a wide range of pathologies. Scalar measures are typically derived within a single-voxel unit, but neighborhood-based texture measures can also be applied. In this work, we propose a new set of descriptors to compute local texture characteristics from scalar measures of diffusion tensor imaging (DTI), such as mean and radial diffusivity, and fractional anisotropy. We employ weighted rotational invariant local operators, namely standard deviation, inter-quartile range, coefficient of variation, quartile coefficient of variation and skewness. Sensitivity and specificity of those texture descriptors were analyzed with tract-based spatial statistics of the white matter on a diffusion MRI group study of elderly healthy controls, patients with mild cognitive impairment (MCI), and mild or moderate Alzheimer's disease (AD). In addition, robustness against noise has been assessed with a realistic diffusion-weighted imaging phantom and the contamination of the local neighborhood with gray matter has been measured. The new texture operators showed an increased ability for finding formerly undetected differences between groups compared to conventional DTI methods. In particular, the coefficient of variation, quartile coefficient of variation, standard deviation and inter-quartile range of the mean and radial diffusivity detected significant differences even between previously not significantly discernible groups, such as MCI versus moderate AD and mild versus moderate AD. The analysis provided evidence of low contamination of the local neighborhood with gray matter and high robustness against noise. The local operators applied here enhance the identification and localization of areas of the brain where cognitive impairment takes place and thus indicate them as promising extensions in diffusion MRI group studies.

Six-minute magnetic resonance imaging protocol for evaluation of acute ischemic stroke: pushing the boundaries.

PubMed

Nael, Kambiz; Khan, Rihan; Choudhary, Gagandeep; Meshksar, Arash; Villablanca, Pablo; Tay, Jennifer; Drake, Kendra; Coull, Bruce M; Kidwell, Chelsea S

2014-07-01

If magnetic resonance imaging (MRI) is to compete with computed tomography for evaluation of patients with acute ischemic stroke, there is a need for further improvements in acquisition speed. Inclusion criteria for this prospective, single institutional study were symptoms of acute ischemic stroke within 24 hours onset, National Institutes of Health Stroke Scale ≥3, and absence of MRI contraindications. A combination of echo-planar imaging (EPI) and a parallel acquisition technique were used on a 3T magnetic resonance (MR) scanner to accelerate the acquisition time. Image analysis was performed independently by 2 neuroradiologists. A total of 62 patients met inclusion criteria. A repeat MRI scan was performed in 22 patients resulting in a total of 84 MRIs available for analysis. Diagnostic image quality was achieved in 100% of diffusion-weighted imaging, 100% EPI-fluid attenuation inversion recovery imaging, 98% EPI-gradient recalled echo, 90% neck MR angiography and 96% of brain MR angiography, and 94% of dynamic susceptibility contrast perfusion scans with interobserver agreements (k) ranging from 0.64 to 0.84. Fifty-nine patients (95%) had acute infarction. There was good interobserver agreement for EPI-fluid attenuation inversion recovery imaging findings (k=0.78; 95% confidence interval, 0.66-0.87) and for detection of mismatch classification using dynamic susceptibility contrast-Tmax (k=0.92; 95% confidence interval, 0.87-0.94). Thirteen acute intracranial hemorrhages were detected on EPI-gradient recalled echo by both observers. A total of 68 and 72 segmental arterial stenoses were detected on contrast-enhanced MR angiography of the neck and brain with k=0.93, 95% confidence interval, 0.84 to 0.96 and 0.87, 95% confidence interval, 0.80 to 0.90, respectively. A 6-minute multimodal MR protocol with good diagnostic quality is feasible for the evaluation of patients with acute ischemic stroke and can result in significant reduction in scan time rivaling that of the multimodal computed tomographic protocol. © 2014 American Heart Association, Inc.

Regularized spherical polar fourier diffusion MRI with optimal dictionary learning.

PubMed

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 sparser coefficients than the original SPF basis and results in significantly lower reconstruction error than Bilgic et al.'s method.

Diagnostic capability of gadoxetate disodium-enhanced liver MRI for diagnosis of hepatocellular carcinoma: comparison with multi-detector CT.

PubMed

Toyota, Naoyuki; Nakamura, Yuko; Hieda, Masashi; Akiyama, Naoko; Terada, Hiroaki; Matsuura, Noriaki; Nishiki, Masayo; Kono, Hirotaka; Kohno, Hiroshi; Irei, Toshimitsu; Yoshikawa, Yukinobu; Kuraoka, Kazuya; Taniyama, Kiyomi; Awai, Kazuo

2013-09-01

The purpose of this study was to evaluate the diagnostic capability of gadoxetate disodium (Gd-EOB)-MRI for the detection of hepatocellular carcinoma (HCC) compared with multidetector CT (MDCT). Fifty patients with 57 surgically proven HCCs who underwent Gd-EOB-MRI and MDCT from March 2008 to June 2011 were evaluated. Two observers evaluated MR and CT on a lesion-by-lesion basis. We analyzed sensitivity by grading on a 5-point scale, the degree of arterial enhancement and the differences in histological grades in the diffusion-weighted images (DWI). The results showed that the sensitivity of Gd-EOB-MRI was higher than that of MDCT especially for HCCs that were 1 cm in diameter or smaller. The hepatobiliary phase was useful for the detecting of small HCC. We had few cases in which it was difficult to judge HCC in the arterial enhancement between MRI and MDCT. In the diffusion-weighted image, well differentiated HCC tended to show a low signal intensity, and poorly differentiated HCC tended to show a high signal intensity. In moderately differentiated HCC's, the mean diameter of the high signal intensity group was larger than that of the low signal intensity group (24.5 mm vs. 15.8 mm). In conclusion, Gd-EOB-MRI tended to show higher sensitivity compared to MDCT in the detection of HCC.

Characteristic MRI findings in hyperglycaemia-induced seizures: diagnostic value of contrast-enhanced fluid-attenuated inversion recovery imaging.

PubMed

Lee, E J; Kim, K K; Lee, E K; Lee, J E

2016-12-01

To describe characteristic magnetic resonance imaging (MRI) abnormalities in hyperglycaemia-induced seizures, and evaluate the diagnostic value of contrast-enhanced fluid-attenuated inversion recovery (FLAIR) imaging. Possible underlying mechanisms of this condition are also discussed. Eleven patients with hyperglycaemia-induced seizures and MRI abnormalities were retrospectively studied. Clinical manifestations, laboratory findings, MRI findings, and clinical outcomes were analysed. All patients, except one, presented with focal seizures, simple or complex partial seizures, or negative motor seizures. All patients had long-standing uncontrolled diabetes mellitus. The MRI abnormalities observed acutely were focal subcortical hypointensities on T2-weighted imaging and FLAIR imaging in all patients with overlying cortical gyral T2 hyperintensities in five. Focal overlying cortical or leptomeningeal enhancement on contrast-enhanced T1-weighted imaging or contrast-enhanced FLAIR imaging was observed in all patients. Contrast-enhanced FLAIR imaging was superior to contrast-enhanced T1-weighted imaging for detecting characteristic cortical or leptomeningeal enhancement. Diffusion-weighted imaging showed mildly restricted diffusion in four of five patients with cortical gyral T2 hyperintensity. In nine patients, the lesions were localised in the parietal or parieto-occipital lobes. The other two patients showed localised precentral gyral lesions. After treatment, the neurological symptoms, including the seizures, improved in all patients. On clinical recovery, the subcortical T2 hypointensity, gyral or leptomeningeal enhancement, and overlying cortical T2 hyperintensities resolved. Recognition of these radiological abnormalities in patients with hyperglycaemia-induced seizures is important in restricting unwarranted investigations and initiating early therapy. These patients generally have a good prognosis. Copyright © 2016 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

IDH mutant and 1p/19q co-deleted oligodendrogliomas: tumor grade stratification using diffusion-, susceptibility-, and perfusion-weighted MRI.

PubMed

Lin, Yu; Xing, Zhen; She, Dejun; Yang, Xiefeng; Zheng, Yingyan; Xiao, Zebin; Wang, Xingfu; Cao, Dairong

2017-06-01

Currently, isocitrate dehydrogenase (IDH) mutation and 1p/19q co-deletion are proven diagnostic biomarkers for both grade II and III oligodendrogliomas (ODs). Non-invasive diffusion-weighted imaging (DWI), susceptibility-weighted imaging (SWI), and dynamic susceptibility contrast perfusion-weighted imaging (DSC-PWI) are widely used to provide physiological information (cellularity, hemorrhage, calcifications, and angiogenesis) of neoplastic histology and tumor grade. However, it is unclear whether DWI, SWI, and DSC-PWI are able to stratify grades of IDH-mutant and 1p/19q co-deleted ODs. We retrospectively reviewed the conventional MRI (cMRI), DWI, SWI, and DSC-PWI obtained on 33 patients with IDH-mutated and 1p/19q co-deleted ODs. Features of cMRI, normalized ADC (nADC), intratumoral susceptibility signals (ITSSs), normalized maxim CBV (nCBV), and normalized maximum CBF (nCBF) were compared between low-grade ODs (LGOs) and high-grade ODs (HGOs). Receiver operating characteristic curve and logistic regression were applied to determine diagnostic performances. HGOs tended to present with prominent edema and enhancement. nADC, ITSSs, nCBV, and nCBF were significantly different between groups (all P < 0.05). The combination of SWI and DSC-PWI for grading resulted in sensitivity and specificity of 100.00 and 93.33%, respectively. IDH-mutant and 1p/19q co-deleted ODs can be stratified by grades using cMRI and advanced magnetic resonance imaging techniques including DWI, SWI, and DSC-PWI. Combined ITSSs with nCBV appear to be a promising option for grading molecularly defined ODs in clinical practice.

Characterization of Cerebral White Matter Properties Using Quantitative Magnetic Resonance Imaging Stains

PubMed Central

Hurley, Samuel A.; Samsonov, Alexey A.; Adluru, Nagesh; Hosseinbor, Ameer Pasha; Mossahebi, Pouria; Tromp, Do P.M.; Zakszewski, Elizabeth; Field, Aaron S.

2011-01-01

Abstract The image contrast in magnetic resonance imaging (MRI) is highly sensitive to several mechanisms that are modulated by the properties of the tissue environment. The degree and type of contrast weighting may be viewed as image filters that accentuate specific tissue properties. Maps of quantitative measures of these mechanisms, akin to microstructural/environmental-specific tissue stains, may be generated to characterize the MRI and physiological properties of biological tissues. In this article, three quantitative MRI (qMRI) methods for characterizing white matter (WM) microstructural properties are reviewed. All of these measures measure complementary aspects of how water interacts with the tissue environment. Diffusion MRI, including diffusion tensor imaging, characterizes the diffusion of water in the tissues and is sensitive to the microstructural density, spacing, and orientational organization of tissue membranes, including myelin. Magnetization transfer imaging characterizes the amount and degree of magnetization exchange between free water and macromolecules like proteins found in the myelin bilayers. Relaxometry measures the MRI relaxation constants T1 and T2, which in WM have a component associated with the water trapped in the myelin bilayers. The conduction of signals between distant brain regions occurs primarily through myelinated WM tracts; thus, these methods are potential indicators of pathology and structural connectivity in the brain. This article provides an overview of the qMRI stain mechanisms, acquisition and analysis strategies, and applications for these qMRI stains. PMID:22432902

68Ga-PSMA PET/MR-Positive, Histopathology-Proven Prostate Cancer in a Patient With Negative Multiparametric Prostate MRI.

PubMed

Muehlematter, Urs J; Rupp, Niels J; Mueller, Julian; Eberli, Daniel; Burger, Irene A

2018-05-25

Multiparametric MRI incorporating T2-weighted, diffusion-weighted, and dynamic contrast material-enhanced sequences is currently used for detection and localization of clinically important prostate cancer (PCa). The Ga-labeled PET tracer targeting the prostate-specific membrane antigen (PSMA, Ga-PSMA-11) is a promising diagnostic approach for staging and restating PCa. Recent studies suggest that Ga-PSMA could also be used for primary PCa detection and localization. We report a case of a Ga-PSMA PET/MR-positive lesion of the peripheral zone in a 73-year-old man with a negative preceding multiparametric MRI. Radical prostatectomy and subsequent histopathologic examination confirmed a Gleason 4 + 4 PCa.

Brain Abnormalities in Congenital Fibrosis of the Extraocular Muscles Type 1: A Multimodal MRI Imaging Study.

PubMed

Miao, Wen; Man, Fengyuan; Wu, Shaoqin; Lv, Bin; Wang, Zhenchang; Xian, Junfang; Sabel, Bernhard A; He, Huiguang; Jiao, Yonghong

2015-01-01

To explore the possible brain structural and functional alterations in congenital fibrosis of extraocular muscles type 1 (CFEOM1) patients using multimodal MRI imaging. T1-weighted, diffusion tensor images and functional MRI data were obtained from 9 KIF21A positive patients and 19 age- and gender-matched healthy controls. Voxel based morphometry and tract based spatial statistics were applied to the T1-weighted and diffusion tensor images, respectively. Amplitude of low frequency fluctuations and regional homogeneity were used to process the functional MRI data. We then compared these multimodal characteristics between CFEOM1 patients and healthy controls. Compared with healthy controls, CFEOM1 patients demonstrated increased grey matter volume in bilateral frontal orbital cortex and in the right temporal pole. No diffusion indices changes were detected, indicating unaffected white matter microstructure. In addition, from resting state functional MRI data, trend of amplitude of low-frequency fluctuations increases were noted in the right inferior parietal lobe and in the right frontal cortex, and a trend of ReHo increase (p<0.001 uncorrected) in the left precentral gyrus, left orbital frontal cortex, temporal pole and cingulate gyrus. CFEOM1 patients had structural and functional changes in grey matter, but the white matter was unaffected. These alterations in the brain may be due to the abnormality of extraocular muscles and their innervating nerves. Future studies should consider the possible correlations between brain morphological/functional findings and clinical data, especially pertaining to eye movements, to obtain more precise answers about the role of brain area changes and their functional consequence in CFEOM1.

Acute hepatic encephalopathy presenting as cortical laminar necrosis: case report.

PubMed

Choi, Jong Mun; Kim, Yoon Hee; Roh, Sook Young

2013-01-01

We report on a 55-year-old man with alcoholic liver cirrhosis who presented with status epilepticus. Laboratory analysis showed markedly elevated blood ammonia. Brain magnetic resonance imaging (MRI) showed widespread cortical signal changes with restricted diffusion, involving both temporo-fronto-parietal cortex, while the perirolandic regions and occipital cortex were uniquely spared. A follow-up brain MRI demonstrated diffuse cortical atrophy with increased signals on T1-weighted images in both the basal ganglia and temporal lobe cortex, representing cortical laminar necrosis. We suggest that the brain lesions, in our case, represent a consequence of toxic effect of ammonia.

A Piglet Model for Detection of Hypoxic-Ischemic Brain Injury with Magnetic Resonance Imaging

PubMed Central

Munkeby, B. H.; De Lange, C.; Emblem, K. E.; Bjørnerud, A.; Kro, G. A. B.; Andresen, J.; Winther-Larssen, E. H.; Løberg, E. M.; Hald, J. K.

2008-01-01

Munkeby BH, de Lange C, Emblem KE, Bjørnerud A, Kro GAB, Andresen J, Winther-Larssen EH, Løberg EM, Hald JK. A piglet model for detection of hypoxic-ischemic brain injury with magnetic resonance imaging. Acta Radiol 2008;49:1049–1057. Background Early detection of hypoxic-ischemic (HI) injury in the asphyxic newborn is important because present prognostic factors are inadequate. Furthermore, therapeutic interventions may have additional benefit if initiated in time. Purpose To assess whether the use of a combined protocol including conventional magnetic resonance imaging (MRI), diffusion-weighted imaging (DWI), diffusion tensor imaging (DTI), and proton MR spectroscopy (MRS) could detect pathological findings in a piglet model 7 hours after HI. Material and Methods Ten piglets were submitted to HI for 30 min followed by reoxygenation with 21% O2 for 7 hours. MRI at 1.5T was done prior to and 7 hours after the HI. Single-voxel proton MRS was performed, and apparent diffusion coefficient (ADC) and fractional anisotropy (FA) were measured in the basal ganglia. MRS identified N-acetylaspartate (NAA), choline (Cho), creatine (Cr), and lactate (Lac). Histology and microtubule-associated protein 2 (MAP-2) staining was performed in the basal ganglia at the end of the experiment. Results Compared to baseline, ADC, NAA/Cho, and NAA/Cr were significantly reduced after 7 hours (P < 0.001, P = 00.01, and P = 00.05, respectively) and FA values were increased (P <0.025). The ratios of Lac/Cho and Lac/NAA were significantly higher after 7 hours compared to baseline (P <0.001). Presence of necrosis correlated well with reduced ADC (RS = 0.91) and presence of Lac (RS = 0.80). Histology and MAP-2 staining showed more than 90% necrosis in eight piglets, 60% in one piglet, and no necrosis in one piglet. Conclusion Diffusion MRI and proton MRS can detect HI injury in the piglet brain 7 hours after hypoxia. DWI and MRS can be used to give useful prognostic information. This piglet model may potentially be used to mimic clinical situations and is suitable for further research investigating HI injury. PMID:18720081

Endometrial cancer: magnetic resonance imaging.

PubMed

Manfredi, R; Gui, B; Maresca, G; Fanfani, F; Bonomo, L

2005-01-01

Carcinoma of the endometrium is the most common invasive gynecologic malignancy of the female genital tract. Clinically, patients with endometrial carcinoma present with abnormal uterine bleeding. The role of magnetic resonance imaging (MRI) in endometrial carcinoma is disease staging and treatment planning. MRI has been shown to be the most valuable imaging mod-ality in this task, compared with endovaginal ultrasound and computed tomography, because of its intrinsic contrast resolution and multiplanar capability. MRI protocol includes axial T1-weighted images; axial, sagittal, and coronal T2-weighted images; and dynamic gadolinium-enhanced T1-weighted imaging. MR examination is usually performed in the supine position with a phased array multicoil using a four-coil configuration. Endometrial carcinoma is isointense with the normal endometrium and myometrium on noncontrast T1-weighted images and has a variable appearance on T2-weighted images demonstrating heterogeneous signal intensity. The appearance of noninvasive endometrial carcinoma on MRI is characterized by a normal or thickened endometrium, with an intact junctional zone and a sharp tumor-myometrium interface. Invasive endometrial carcinoma is characterized disruption or irregularity of the junctional zone by intermediate signal intensity mass on T2-weighted images. Invasion of the cervical stroma is diagnosed when the low signal intensity cervical stroma is disrupted by the higher signal intensity endometrial carcinoma. MRI in endometrial carcinoma performs better than other imaging modalities in disease staging and treatment planning. Further, the accuracy and the cost of MRI are equivalent to those of surgical staging.

Differentiation of malignant from benign soft tissue tumours: use of additive qualitative and quantitative diffusion-weighted MR imaging to standard MR imaging at 3.0 T.

PubMed

Lee, So-Yeon; Jee, Won-Hee; Jung, Joon-Yong; Park, Michael Y; Kim, Sun-Ki; Jung, Chan-Kwon; Chung, Yang-Guk

2016-03-01

To determine the added value of diffusion-weighted imaging (DWI) to standard magnetic resonance imaging (MRI) to differentiate malignant from benign soft tissue tumours at 3.0 T. 3.0 T MR images including DWI in 63 patients who underwent surgery for soft tissue tumours were retrospectively analyzed. Two readers independently interpreted MRI for the presence of malignancy in two steps: standard MRI alone, standard MRI and DWI with qualitative and quantitative analysis combined. There were 34 malignant and 29 non-malignant soft tissue tumours. In qualitative analysis, hyperintensity relative to skeletal muscle was more frequent in malignant than benign tumours on DWI (P=0.003). In quantitative analysis, ADCs of malignant tumours were significantly lower than those of non-malignant tumours (P≤0.002): 759±385 vs. 1188±423 μm(2)/sec minimum ADC value, 941±440 vs. 1310±440 μm(2)/sec average ADC value. The mean sensitivity, specificity and accuracy of both readers were 96%, 72%, and 85% on standard MRI alone and 97%, 90%, and 94% on standard MRI with DWI. The addition of DWI to standard MRI improves the diagnostic accuracy for differentiation of malignant from benign soft tissue tumours at 3.0 T. DWI has added value for differentiating malignant from benign soft tissue tumours. Addition of DWI to standard MRI at 3.0 T improves the diagnostic accuracy. Measurements of both ADC min within solid portion and ADC av are helpful.

Diffusion-weighted imaging of the breast: principles and clinical applications.

PubMed

Woodhams, Reiko; Ramadan, Saadallah; Stanwell, Peter; Sakamoto, Satoko; Hata, Hirofumi; Ozaki, Masanori; Kan, Shinichi; Inoue, Yusuke

2011-01-01

Diffusion-weighted imaging provides a novel contrast mechanism in magnetic resonance (MR) imaging and has a high sensitivity in the detection of changes in the local biologic environment. A significant advantage of diffusion-weighted MR imaging over conventional contrast material-enhanced MR imaging is its high sensitivity to change in the microscopic cellular environment without the need for intravenous contrast material injection. Approaches to the assessment of diffusion-weighted breast imaging findings include assessment of these data alone and interpretation of the data in conjunction with T2-weighted imaging findings. In addition, the analysis of apparent diffusion coefficient (ADC) value can be undertaken either in isolation or in combination with diffusion-weighted and T2-weighted imaging. Most previous studies have evaluated ADC value alone; however, overlap in the ADC values of malignant and benign disease has been observed. This overlap may be partly due to selection of b value, which can influence the concomitant effect of perfusion and emphasize the contribution of multicomponent model influences. The simultaneous assessment of diffusion-weighted and T2-weighted imaging data and ADC value has the potential to improve specificity. In addition, the use of diffusion-weighted imaging in a standard breast MR imaging protocol may heighten sensitivity and thereby improve diagnostic accuracy. Standardization of diffusion-weighted imaging parameters is needed to allow comparison of multicenter studies and assessment of the clinical utility of diffusion-weighted imaging and ADC values in breast evaluation.

Apparent diffusion coefficient of the normal human brain for various experimental conditions

NASA Astrophysics Data System (ADS)

Moraru, Luminita; Dimitrievici, Lucian

2017-01-01

Diffusion-Weighted Magnetic Resonance Imaging (DW-MRI) is being increasingly used to assess both brain tissues and cerebrospinal fluid integrity. In this paper we study inter-site reproducibility of the apparent diffusion coefficient values for the main cerebral tissues such as gray matter, white matter and into cerebrospinal fluid and for three different stacks of slices that were spaced at L = 79.8, 84.9 and 90 mm. We assessed the impact of the attenuation factor and diffusion gradient on the results reproducibility.

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

PubMed Central

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

2016-01-01

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

MRI findings of neuronal ceroid lipofuscinosis in a cat

PubMed Central

White, Crystal; Mortier, Jeremy; Verin, Ranieri; Maddox, Thomas; Goncalves, Rita; Sanchez-Masian, Daniel

2018-01-01

Case summary A 2-year-old male domestic shorthair cat presented to the University of Liverpool Small Animal Teaching Hospital with a 2 week history of altered mentation, blindness and focal epileptic seizures. MRI examination revealed generalised cerebral and cerebellar atrophy, diffuse T2-weighted hyperintensity of the white matter and meningeal thickening. Neuronal ceroid lipofuscinosis was confirmed on post-mortem examination. Relevance and novel information This is the first report of the MRI findings of neuronal ceroid lipofuscinosis in a cat. PMID:29531776

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

PubMed

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

2014-10-01

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.

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

PubMed

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) under the three orthogonal orientations. The detected errors were 0.474 ± 0.355 mm, 0.475 ± 0.287 mm, and 0.546 ± 0.336 mm in the axial, coronal, and sagittal plane. DW-ssEPI, however, failed the tests due to severe distortion and low signal intensity. Noise correction must be performed for the DW-ssEPI to avoid ADC quantitation errors, whereas it is optional for DP-TSE. At 0 °C, the two sequences provided accurate quantitation with < 3% variation with the reference. In the room temperature study, discrepancies between ADCs from DP-TSE and the reference were within 4%, but could be as high as 8% for DW-ssEPI after the noise correction. Excellent ADC reproducibility with a coefficient of variation < 5% was observed among the 10 measurements of DP-TSE, indicating desirable robustness for ADC-based tumor response assessment. In vivo TRE in DP-TSE was less than 1.6 mm overall, whereas it could be greater than 12 mm in DW-ssEPI. For GBM patients, the CSF and brain tissue ADCs from DP-TSE were within the ranges found in literature. ADC differences between the two techniques were within 8% among the six sarcoma patients. For the reference tube that had a relatively low diffusivity, the two diffusion sequences provided matched measurements. A diffusion technique with excellent geometric fidelity, accurate, and reproducible ADC measurement was demonstrated for longitudinal tumor response assessment using a low-field MRI-guided radiotherapy system. © 2017 American Association of Physicists in Medicine.

MRI for the detection of calcific features of vertebral haemangioma.

PubMed

Bender, Y Y; Böker, S M; Diederichs, G; Walter, T; Wagner, M; Fallenberg, E; Liebig, T; Rickert, M; Hamm, B; Makowski, M R

2017-08-01

To evaluate the diagnostic performance of susceptibility-weighted-magnetic-resonance imaging (SW-MRI) for the detection of vertebral haemangiomas (VHs) compared to T1/T2-weighted MRI sequences, radiographs, and computed tomography (CT). The study was approved by the local ethics review board. An SW-MRI sequence was added to the clinical spine imaging protocol. The image-based diagnosis of 56 VHs in 46 patients was established using T1/T2 MRI in combination with radiography/CT as the reference standard. VHs were assessed based on T1/T2-weighted MRI images alone and in combination with SW-MRI, while radiographs/CT images were excluded from the analysis. Fifty-one of 56 VHs could be identified on T1/T2 MRI images alone, if radiographs/CT images were excluded from analysis. In five cases (9.1%), additional radiographs/CT images were required for the imaging-based diagnosis. If T1/T2 and SW-MRI images were used in combination, all VHs could be diagnosed, without the need for radiography/CT. Size measurements revealed a close correlation between CT and SW-MRI (R 2 =0.94; p<0.05). This study demonstrates that SW-MRI enables reliable detection of the typical calcified features of VHs. This is of importance for routine MRI of the spine, as the use of additional CT/radiography can be minimized. Copyright © 2017 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.

Diffusion-weighted imaging in relation to morphology on dynamic contrast enhancement MRI: the diagnostic value of characterizing non-puerperal mastitis.

PubMed

Zhang, Lina; Hu, Jiani; Guys, Nicholas; Meng, Jinli; Chu, Jianguo; Zhang, Weisheng; Liu, Ailian; Wang, Shaowu; Song, Qingwei

2018-03-01

To demonstrate the value of diffusion-weighted imaging (DWI) in the characterisation of mastitis lesions. Sixty-one non-puerperal patients with pathologically confirmed single benign mastitis lesions underwent preoperative examinations with conventional MRI and axial DWI. Patients were categorised into three groups: (1) periductal mastitis (PDM), (2) granulomatous lobular mastitis (GLM), and (3) infectious abscess (IAB). Apparent diffusion coefficient (ADC) values of each lesion were recorded. A one-way ANOVA with logistic analysis was performed to compare ADC values and other parameters. Discriminative abilities of DWI modalities were compared using the area under the receiver operating characteristic curve (AUC). P < 0.05 was considered statistically significant. ADC values differed significantly among the three groups (P = 0.003) as well as between PDM and IAB and between PDM and GLM. The distribution of non-mass enhancement on dynamic contrast-enhanced (DCE) MRI differed significantly among the three groups (P = 0.03) but not between any two groups specifically. There were no differences in lesion location, patient age, T 2 WI or DWI signal intensity, enhancement type, non-mass internal enhancement, or mass enhancement characteristics among the three groups. ADC values and the distribution of non-mass enhancement are valuable in classifying mastitis subtypes. • Mastitis subtypes exhibit different characteristics on DWI and DCE MRI. • ADC values are helpful in isolating PDM from other mastitis lesions. • Distribution of non-mass enhancement also has value in comparing mastitis subtypes.

Incorporation of diffusion-weighted magnetic resonance imaging data into a simple mathematical model of tumor growth

NASA Astrophysics Data System (ADS)

Atuegwu, N. C.; Colvin, D. C.; Loveless, M. E.; Xu, L.; Gore, J. C.; Yankeelov, T. E.

2012-01-01

We build on previous work to show how serial diffusion-weighted MRI (DW-MRI) data can be used to estimate proliferation rates in a rat model of brain cancer. Thirteen rats were inoculated intracranially with 9L tumor cells; eight rats were treated with the chemotherapeutic drug 1,3-bis(2-chloroethyl)-1-nitrosourea and five rats were untreated controls. All animals underwent DW-MRI immediately before, one day and three days after treatment. Values of the apparent diffusion coefficient (ADC) were calculated from the DW-MRI data and then used to estimate the number of cells in each voxel and also for whole tumor regions of interest. The data from the first two imaging time points were then used to estimate the proliferation rate of each tumor. The proliferation rates were used to predict the number of tumor cells at day three, and this was correlated with the corresponding experimental data. The voxel-by-voxel analysis yielded Pearson's correlation coefficients ranging from -0.06 to 0.65, whereas the region of interest analysis provided Pearson's and concordance correlation coefficients of 0.88 and 0.80, respectively. Additionally, the ratio of positive to negative proliferation values was used to separate the treated and control animals (p <0.05) at an earlier point than the mean ADC values. These results further illustrate how quantitative measurements of tumor state obtained non-invasively by imaging can be incorporated into mathematical models that predict tumor growth.

Plain magnetic resonance imaging as an alternative in evaluating inflammation and bowel damage in inflammatory bowel disease--a prospective comparison with conventional magnetic resonance follow-through.

PubMed

Jesuratnam-Nielsen, Kayalvily; Løgager, Vibeke B; Rezanavaz-Gheshlagh, Bijan; Munkholm, Pia; Thomsen, Henrik S

2015-05-01

To compare prospectively the diagnostic accuracy of magnetic resonance imaging (MRI) without use of contrast medium orally or intravenously (plain MRI) with magnetic resonance follow-through (MRFT) in patients with inflammatory bowel disease (IBD). Plain MRI was carried out in addition to MRFT, to which the patients were referred. All patients underwent both examinations on the same day. For the evaluation, the bowel was divided into nine segments. Two radiologists, blinded to clinical findings, evaluated bowel wall thickness, diffusion weighted imaging (DWI), and other inflammatory changes in each bowel segments. Further, hyperenhancement of the bowel was also evaluated in MRFT. A total of 100 patients (40 males and 60 females; median age: 38.5; range: 19-90) were enrolled; 44 with Crohn's disease (CD), 25 with ulcerative colitis (UC), 24 with IBD unclassified (IBD-U), and 7 had other diagnosis. Sensitivity, specificity, and accuracy in CD ranged 50-86%, 93-94%, and 91-92% for wall thickening and 49-82%, 85-93%, and 84-89% for DWI, respectively. Sensitivity, specificity, and accuracy in UC range 0-40%, 87-100%, and 80-100% for wall thickening and 0-52%, 83-94% and 76-92% for DWI, respectively. The κ values for bowel wall thickening, DWI, and mural hyperenhancement were detected with fair agreement (κ = 0.26-0.39) at both MRI examinations, whereas only bowel wall thickening in MRFT were detected with moderate agreement (κ = 0.47) Conclusion. Plain MRI cannot currently replace MRFT in the workup of patients with IBD. Further research on plain MRI is needed to improve the protocol.

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

PubMed

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

2018-04-01

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 1,085×10 -6 mm 2 s -1 , interquartile range 927-1,295×10 -6 mm 2 s -1 ) was significantly higher than the ADC of malignant focal deposits (97 ROIs, median ADC 682×10 -6 mm 2 s -1 , interquartile range 583-781×10 -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 872×10 -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. • Whole-body diffusion-weighted MRI is becoming widely used in myeloma and bone metastases. • ADC values of vertebral haemangiomas are significantly higher than malignant focal deposits. • High ADCs of haemangiomas allows them to be distinguished from active disease.

Serial MR diffusion to predict treatment response in high-grade pediatric brain tumors: a comparison of regional and voxel-based diffusion change metrics

PubMed Central

Rodriguez Gutierrez, Daniel; Manita, Muftah; Jaspan, Tim; Dineen, Robert A.; Grundy, Richard G.; Auer, Dorothee P.

2013-01-01

Background Assessment of treatment response by measuring tumor size is known to be a late and potentially confounded response index. Serial diffusion MRI has shown potential for allowing earlier and possibly more reliable response assessment in adult patients, with limited experience in clinical settings and in pediatric brain cancer. We present a retrospective study of clinical MRI data in children with high-grade brain tumors to assess and compare the values of several diffusion change metrics to predict treatment response. Methods Eighteen patients (age range, 1.9–20.6 years) with high-grade brain tumors and serial diffusion MRI (pre- and posttreatment interval range, 1–16 weeks posttreatment) were identified after obtaining parental consent. The following diffusion change metrics were compared with the clinical response status assessed at 6 months: (1) regional change in absolute and normalized apparent diffusivity coefficient (ADC), (2) voxel-based fractional volume of increased (fiADC) and decreased ADC (fdADC), and (3) a new metric based on the slope of the first principal component of functional diffusion maps (fDM). Results Responders (n = 12) differed significantly from nonresponders (n = 6) in all 3 diffusional change metrics demonstrating higher regional ADC increase, larger fiADC, and steeper slopes (P < .05). The slope method allowed the best response prediction (P < .01, η2 = 0.78) with a classification accuracy of 83% for a slope of 58° using receiver operating characteristic (ROC) analysis. Conclusions We demonstrate that diffusion change metrics are suitable response predictors for high-grade pediatric tumors, even in the presence of variable clinical diffusion imaging protocols. PMID:23585630

Isotropic non-white matter partial volume effects in constrained spherical deconvolution.

PubMed

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

2014-01-01

Diffusion-weighted (DW) magnetic resonance imaging (MRI) is a non-invasive imaging method, which can be used to investigate neural tracts in the white matter (WM) of the brain. Significant partial volume effects (PVEs) are present in the DW signal due to relatively large voxel sizes. These PVEs can be caused by both non-WM tissue, such as gray matter (GM) and cerebrospinal fluid (CSF), and by multiple non-parallel WM fiber populations. High angular resolution diffusion imaging (HARDI) methods have been developed to correctly characterize complex WM fiber configurations, but to date, many of the HARDI methods do not account for non-WM PVEs. In this work, we investigated the isotropic PVEs caused by non-WM tissue in WM voxels on fiber orientations extracted with constrained spherical deconvolution (CSD). Experiments were performed on simulated and real DW-MRI data. In particular, simulations were performed to demonstrate the effects of varying the diffusion weightings, signal-to-noise ratios (SNRs), fiber configurations, and tissue fractions. Our results show that the presence of non-WM tissue signal causes a decrease in the precision of the detected fiber orientations and an increase in the detection of false peaks in CSD. We estimated 35-50% of WM voxels to be affected by non-WM PVEs. For HARDI sequences, which typically have a relatively high degree of diffusion weighting, these adverse effects are most pronounced in voxels with GM PVEs. The non-WM PVEs become severe with 50% GM volume for maximum spherical harmonics orders of 8 and below, and already with 25% GM volume for higher orders. In addition, a low diffusion weighting or SNR increases the effects. The non-WM PVEs may cause problems in connectomics, where reliable fiber tracking at the WM-GM interface is especially important. We suggest acquiring data with high diffusion-weighting 2500-3000 s/mm(2), reasonable SNR (~30) and using lower SH orders in GM contaminated regions to minimize the non-WM PVEs in CSD.

Clinical utility of apparent diffusion coefficient values obtained using high b-value when diagnosing prostate cancer using 3 tesla MRI: comparison between ultra-high b-value (2000 s/mm²) and standard high b-value (1000 s/mm²).

PubMed

Kitajima, Kazuhiro; Takahashi, Satoru; Ueno, Yoshiko; Yoshikawa, Takeshi; Ohno, Yoshiharu; Obara, Makoto; Miyake, Hideaki; Fujisawa, Masato; Sugimura, Kazuro

2012-07-01

To determine whether the apparent diffusion coefficient (ADC) obtained using b = 2000 s/mm(2) upon 3 Tesla (T) diffusion-weighted MRI is superior to b = 1000 s/mm(2) for discriminating malignant from normal prostate tissue and predicting the aggressiveness of prostate cancer, using histopathological findings of radical prostatectomy as a reference. Eighty prostate cancer patients underwent preoperative 3T MRI including diffusion weighted imaging with b-values of 0, 1000, and 2000 s/mm(2) . ADCs were measured for malignant lesions and normal sites on three sets of ADC maps calculated with monoexponential fitting between b = 0 and 1000, 0 and 2000, and 1000 and 2000, respectively. The relationship between the ADC and Gleason score was evaluated. The areas under the ROC curves for b = 0,1000, b = 0,2000, and b = 1000,2000 were 0.896, 0.937, and 0.857, respectively, in the peripheral zone (PZ) and 0.877, 0.889, and 0.731, respectively, in the transition zone (TZ). The difference between b = 0,1000 and b = 0,2000 was significant in PZ (P = 0.033), but not in TZ (P = 0.84). Weak but significant negative correlations were identified between ADCs and Gleason score in both PZ and TZ cancer at b = 0,1000 and b = 0,2000 (r = -0.323 to -0.341). For 3T MRI, ADCs using b = 0,2000 are more accurate than b = 0,1000 for diagnosing PZ cancer, and as accurate for TZ cancer. Copyright © 2012 Wiley Periodicals, Inc.

Tay's syndrome: MRI.

PubMed

Porto, L; Weis, R; Schulz, C; Reichel, P; Lanfermann, H; Zanella, F E

2000-11-01

Tay's syndrome is a trichothiodystrophy associated with congenital ichthyosis. We report the findings on MRI and spectroscopy in a young girl with sparse, short, ruffled hair, dry skin and delayed milestones. T2-weighted images showed prominent diffuse confluent increase in signal symmetrically in all the supratentorial white matter. These findings are similar to those in a previously described case, and consistent with dysmyelination. Spectroscopy showed increased myoinositol and decreased choline.

The release of Doxorubicin from liposomes monitored by MRI and triggered by a combination of US stimuli led to a complete tumor regression in a breast cancer mouse model.

PubMed

Rizzitelli, S; Giustetto, P; Faletto, D; Delli Castelli, D; Aime, S; Terreno, E

2016-05-28

The work aimed at developing a novel MRI-based theranostic protocol for improving the anticancer efficacy of a Doxil-like liposomal formulation. The goal was achieved stimulating the intratumor release of the drug from the nanocarrier and favoring its diffusion in the lesion by the sequential application of low-intensity pulsed ultrasound. The protocol was tested on mice bearing a syngeneic breast cancer model. The combination of acoustic waves with different characteristics allowed for: i) the release of the drug and the co-encapsulated MRI agent (Gadoteridol) from the liposomes in the vessels of the tumor region, and ii) the extravasation of the released material, as well as intact liposomes, in the tumor stroma. The MR-T1 contrast enhancement measured in the tumor reported on the delivery and US-triggered release of Doxorubicin. The developed protocol resulted in a marked increase in the intratumor drug concentration that, in turn, led to the complete regression of the lesion. The protocol has a good clinical translatability because all the components of the theranostic agent (Doxorubicin, liposomes, Gadoteridol) are approved for human use. Copyright © 2016 Elsevier B.V. All rights reserved.

Association of quantitative magnetic resonance imaging parameters with histological findings from MRI/ultrasound fusion prostate biopsy.

PubMed

Dianat, Seyed Saeid; Carter, H Ballentine; Schaeffer, Edward M; Hamper, Ulrik M; Epstein, Jonathan I; Macura, Katarzyna J

2015-10-01

Purpose of this pilot study was to correlate quantitative parameters derived from the multiparametric magnetic resonance imaging (MP-MRI) of the prostate with results from MRI guided transrectal ultrasound (MRI/TRUS) fusion prostate biopsy in men with suspected prostate cancer. Thirty-nine consecutive patients who had 3.0T MP-MRI and subsequent MRI/TRUS fusion prostate biopsy were included and 73 MRI-identified targets were sampled by 177 cores. The pre-biopsy MP-MRI consisted of T2-weighted, diffusion weighted (DWI), and dynamic contrast enhanced (DCE) images. The association of quantitative MRI measurements with biopsy histopathology findings was assessed by Mann-Whitney U- test and Kruskal-Wallis test. Of 73 targets, biopsy showed benign prostate tissue in 46 (63%), cancer in 23 (31.5%), and atypia/high grade prostatic intraepithelial neoplasia in four (5.5%) targets. The median volume of cancer-positive targets was 1.3 cm3. The cancer-positive targets were located in the peripheral zone (56.5%), transition zone (39.1%), and seminal vesicle (4.3%). Nine of 23 (39.1%) cancer-positive targets were higher grade cancer (Gleason grade > 6). Higher grade targets and cancer-positive targets compared to benign lesions exhibited lower mean apparent diffusion coefficient (ADC) value (952.7 < 1167.9 < 1278.9), and lower minimal extracellular volume fraction (ECF) (0.13 < 0.185 < 0.213), respectively. The difference in parameters was more pronounced between higher grade cancer and benign lesions. Our findings from a pilot study indicate that quantitative MRI parameters can predict malignant histology on MRI/TRUS fusion prostate biopsy, which is a valuable technique to ensure adequate sampling of MRI-visible suspicious lesions under TRUS guidance and may impact patient management. The DWI-based quantitative measurement exhibits a stronger association with biopsy findings than the other MRI parameters.

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

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

Gao, Y; Yang, Y; Rangwala, N

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 geometricmore » 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 excellent geometric fidelity, accurate and highly reproducible ADC measurements was proposed for longitudinal tumor response assessment using an MRI-guided RT system. Yu Gao acknowledges research support from ViewRay.« less

Can we develop pathology-specific MRI contrast for "MR-negative" epilepsy?

PubMed

Feindel, Kirk W

2013-05-01

Recent improvements in magnetic resonance imaging (MRI) hardware, software, and analysis routines are helping to put cases of "MR-negative" epilepsy on the decline. However, most standard-of-care MRI relies on careful manipulation and presentation of T1, T2, and diffusion-weighted contrast, which characterize the behavior of water in "bulk" tissue rather than providing pathology-specific contrast. Research efforts in MR physics continue to identify and develop novel theory, and methods such as diffusional kurtosis imaging (DKI) and temporal diffusion spectroscopy that can better characterize tissue substructure, and chemical exchange saturation transfer (CEST) that can target underlying biochemical processes. The potential role of each technique in targeting pathologies implicated in "MR-negative" epilepsy is outlined herein. Wiley Periodicals, Inc. © 2013 International League Against Epilepsy.

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

PubMed

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 findings suggest that SVM, using features from a combination of diffusion models, improves prediction accuracy for differentiation of benign versus malignant breast tumors, and may further assist in subtyping of breast cancer. 3 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2018;47:1205-1216. © 2017 International Society for Magnetic Resonance in Medicine.

Medulloblastoma with Atypical Dynamic Imaging Changes: Case Report with Literature Review.

PubMed

Song, Shuang-Shuang; Wang, Jian-Hong; Fu, Wei-Wei; Li, Ying; Sui, Qing-Lan; Liu, Xue-Jun

2017-09-01

We analyzed a case of medulloblastoma with atypical dynamic imaging changes retrospectively to summarize the atypical magnetic resonance imaging (MRI) features of medulloblastoma by reviewing the literature. An atypical case of medulloblastoma in the cerebellar hemisphere confirmed by pathology was analyzed retrospectively, and the literature about it was reviewed. The radiologic findings of the patient were based on 3 examinations. The first examination showed that the cortex of the bilateral cerebellar hemisphere had diffuse nodular thickening, with a high signal on diffusion-weighted imaging and significant enhancement. Contrast enhancement MRI 1 year later showed the signal of cerebellar hemisphere returned to normal but revealed an enhanced nodule. A reexamination 6 months later showed an irregular mass with a high-density shadow in the cerebellar vermis on CT scan. The T2-weighted image revealed multiple degenerative cysts, and the mass had significant enhancement. The radiologic characteristics of atypical medulloblastomas vary in adults and children. Understanding the radiologic characteristics of medulloblastomas, such as MRI features, age of onset, and location of atypical medulloblastomas, can help improve the diagnosis of medulloblastomas. Copyright © 2017. Published by Elsevier Inc.

Studying Autism Spectrum Disorder with Structural and Diffusion Magnetic Resonance Imaging: A Survey

PubMed Central

Ismail, Marwa M. T.; Keynton, Robert S.; Mostapha, Mahmoud M. M. O.; ElTanboly, Ahmed H.; Casanova, Manuel F.; Gimel'farb, Georgy L.; El-Baz, Ayman

2016-01-01

Magnetic resonance imaging (MRI) modalities have emerged as powerful means that facilitate non-invasive clinical diagnostics of various diseases and abnormalities since their inception in the 1980s. Multiple MRI modalities, such as different types of the sMRI and DTI, have been employed to investigate facets of ASD in order to better understand this complex syndrome. This paper reviews recent applications of structural magnetic resonance imaging (sMRI) and diffusion tensor imaging (DTI), to study autism spectrum disorder (ASD). Main reported findings are sometimes contradictory due to different age ranges, hardware protocols, population types, numbers of participants, and image analysis parameters. The primary anatomical structures, such as amygdalae, cerebrum, and cerebellum, associated with clinical-pathological correlates of ASD are highlighted through successive life stages, from infancy to adulthood. This survey demonstrates the absence of consistent pathology in the brains of autistic children and lack of research investigations in patients under 2 years of age in the literature. The known publications also emphasize advances in data acquisition and analysis, as well as significance of multimodal approaches that combine resting-state, task-evoked, and sMRI measures. Initial results obtained with the sMRI and DTI show good promise toward the early and non-invasive ASD diagnostics. PMID:27242476

Comparisons among MRI signs, apparent diffusion coefficient, and fractional anisotropy in dogs with a solitary intracranial meningioma or histiocytic sarcoma.

PubMed

Wada, Masae; Hasegawa, Daisuke; Hamamoto, Yuji; Yu, Yoshihiko; Fujiwara-Igarashi, Aki; Fujita, Michio

2017-07-01

Although MRI has become widely used in small animal practice, little is known about the validity of advanced MRI techniques such as diffusion-weighted imaging and diffusion tensor imaging. The aim of this retrospective analytical observational study was to investigate the characteristics of diffusion parameters, that is the apparent diffusion coefficient and fractional anisotropy, in dogs with a solitary intracranial meningioma or histiocytic sarcoma. Dogs were included based on the performance of diffusion MRI and histological confirmation. Statistical analyses were performed to compare apparent diffusion coefficient and fractional anisotropy for the two types of tumor in the intra- and peritumoral regions. Eleven cases with meningioma and six with histiocytic sarcoma satisfied the inclusion criteria. Significant differences in apparent diffusion coefficient value (× 10 -3 mm 2 /s) between meningioma vs. histiocytic sarcoma were recognized in intratumoral small (1.07 vs. 0.76) and large (1.04 vs. 0.77) regions of interest, in the peritumoral margin (0.93 vs. 1.08), and in the T2 high region (1.21 vs. 1.41). Significant differences in fractional anisotropy values were found in the peritumoral margin (0.29 vs. 0.24) and the T2 high region (0.24 vs. 0.17). The current study identified differences in measurements of apparent diffusion coefficient and fractional anisotropy for meningioma and histiocytic sarcoma in a small sample of dogs. In addition, we observed that all cases of intracranial histiocytic sarcoma showed leptomeningeal enhancement and/or mass formation invading into the sulci in the contrast study. Future studies are needed to determine the sensitivity of these imaging characteristics for differentiating between these tumor types. © 2017 American College of Veterinary Radiology.

Automated two-point dixon screening for the evaluation of hepatic steatosis and siderosis: comparison with R2-relaxometry and chemical shift-based sequences.

PubMed

Henninger, B; Zoller, H; Rauch, S; Schocke, M; Kannengiesser, S; Zhong, X; Reiter, G; Jaschke, W; Kremser, C

2015-05-01

To evaluate the automated two-point Dixon screening sequence for the detection and estimated quantification of hepatic iron and fat compared with standard sequences as a reference. One hundred and two patients with suspected diffuse liver disease were included in this prospective study. The following MRI protocol was used: 3D-T1-weighted opposed- and in-phase gradient echo with two-point Dixon reconstruction and dual-ratio signal discrimination algorithm ("screening" sequence); fat-saturated, multi-gradient-echo sequence with 12 echoes; gradient-echo T1 FLASH opposed- and in-phase. Bland-Altman plots were generated and correlation coefficients were calculated to compare the sequences. The screening sequence diagnosed fat in 33, iron in 35 and a combination of both in 4 patients. Correlation between R2* values of the screening sequence and the standard relaxometry was excellent (r = 0.988). A slightly lower correlation (r = 0.978) was found between the fat fraction of the screening sequence and the standard sequence. Bland-Altman revealed systematically lower R2* values obtained from the screening sequence and higher fat fraction values obtained with the standard sequence with a rather high variability in agreement. The screening sequence is a promising method with fast diagnosis of the predominant liver disease. It is capable of estimating the amount of hepatic fat and iron comparable to standard methods. • MRI plays a major role in the clarification of diffuse liver disease. • The screening sequence was introduced for the assessment of diffuse liver disease. • It is a fast and automated algorithm for the evaluation of hepatic iron and fat. • It is capable of estimating the amount of hepatic fat and iron.

Magnetic Resonance Imaging of Liver Metastasis.

PubMed

Karaosmanoglu, Ali Devrim; Onur, Mehmet Ruhi; Ozmen, Mustafa Nasuh; Akata, Deniz; Karcaaltincaba, Musturay

2016-12-01

Liver magnetic resonance imaging (MRI) is becoming the gold standard in liver metastasis detection and treatment response assessment. The most sensitive magnetic resonance sequences are diffusion-weighted images and hepatobiliary phase images after Gd-EOB-DTPA. Peripheral ring enhancement, diffusion restriction, and hypointensity on hepatobiliary phase images are hallmarks of liver metastases. In patients with normal ultrasonography, computed tomography (CT), and positron emission tomography (PET)-CT findings and high clinical suspicion of metastasis, MRI should be performed for diagnosis of unseen metastasis. In melanoma, colon cancer, and neuroendocrine tumor metastases, MRI allows confident diagnosis of treatment-related changes in liver and enables differential diagnosis from primary liver tumors. Focal nodular hyperplasia-like nodules in patients who received platinum-based chemotherapy, hypersteatosis, and focal fat can mimic metastasis. In cancer patients with fatty liver, MRI should be preferred to CT. Although the first-line imaging for metastases is CT, MRI can be used as a problem-solving method. MRI may be used as the first-line method in patients who would undergo curative surgery or metastatectomy. Current limitation of MRI is low sensitivity for metastasis smaller than 3mm. MRI fingerprinting, glucoCEST MRI, and PET-MRI may allow simpler and more sensitive diagnosis of liver metastasis. Copyright © 2016 Elsevier Inc. All rights reserved.

Imaging laminar structures in the gray matter with diffusion MRI.

PubMed

Assaf, Yaniv

2018-01-05

The cortical layers define the architecture of the gray matter and its neuroanatomical regions and are essential for brain function. Abnormalities in cortical layer development, growth patterns, organization, or size can affect brain physiology and cognition. Unfortunately, while large population studies are underway that will greatly increase our knowledge about these processes, current non-invasive techniques for characterizing the cortical layers remain inadequate. For decades, high-resolution T1 and T2 Weighted Magnetic Resonance Imaging (MRI) have been the method-of-choice for gray matter and layer characterization. In the past few years, however, diffusion MRI has shown increasing promise for its unique insights into the fine structure of the cortex. Several different methods, including surface analysis, connectivity exploration, and sub-voxel component modeling, are now capable of exploring the diffusion characteristics of the cortex. In this review, we will discuss current advances in the application of diffusion imaging for cortical characterization and its unique features, with a particular emphasis on its spatial resolution, arguably its greatest limitation. In addition, we will explore the relationship between the diffusion MRI signal and the cellular components of the cortex, as visualized by histology. While the obstacles facing the widespread application of cortical diffusion imaging remain daunting, the information it can reveal may prove invaluable. Within the next few years, we predict a surge in the application of this technique and a concomitant expansion of our knowledge of cortical layers. Copyright © 2018 Elsevier Inc. All rights reserved.

Diagnostic problems in case of twin pregnancies: US vs. MRI study.

PubMed

Bekiesinska-Figatowska, Monika; Herman-Sucharska, Izabela; Romaniuk-Doroszewska, Anna; Jaczynska, Renata; Furmanek, Mariusz; Bragoszewska, Hanna

2013-09-01

To present an experience with twin pregnancies underlining the impact of magnetic resonance imaging (MRI) on diagnosis and management. There were 17 cases of twin pregnancies: nine monochorionic [including four monochorionic diamniotic and five monochorionic monoamniotic (conjoined twins)] and eight dichorionic. The MRI examinations were performed between 19 and 39 weeks of gestational age in two centers using 1.5 T scanners (GE Signa Excite and GE Signa HDxt; GE Healthcare, Waukesha, WI, USA), always after ultrasound (US). In the first period of our activity, SSFSE sequence in T2-weighted images (SSFSE/T2WI) was the main diagnostic tool supported by TSE or GRE T1-weighted images (T1WI). After upgrading the scanners, diffusion-weighted imaging (DWI), steady-state free precession (FIESTA), and echoplanar GRE imaging (EPIGRE) became available. In 11 cases (64.7%), MRI was superior to US and supplied additional information, including two cases in which pathology of the second twin suspected on US was ruled out on the basis of MRI. In six cases (35.3%) MRI confirmed US diagnosis and brought no new data. MRI offers more detailed assessment of fetal pathology in cases of twin pregnancies, including conjoined twins, in which sonographic evaluation is more difficult than in single cases.

Fetal MRI: A Technical Update with Educational Aspirations

PubMed Central

Gholipour, Ali; Estroff, Judith A.; Barnewolt, Carol E.; Robertson, Richard L.; Grant, P. Ellen; Gagoski, Borjan; Warfield, Simon K.; Afacan, Onur; Connolly, Susan A.; Neil, Jeffrey J.; Wolfberg, Adam; Mulkern, Robert V.

2015-01-01

Fetal magnetic resonance imaging (MRI) examinations have become well-established procedures at many institutions and can serve as useful adjuncts to ultrasound (US) exams when diagnostic doubts remain after US. Due to fetal motion, however, fetal MRI exams are challenging and require the MR scanner to be used in a somewhat different mode than that employed for more routine clinical studies. Herein we review the techniques most commonly used, and those that are available, for fetal MRI with an emphasis on the physics of the techniques and how to deploy them to improve success rates for fetal MRI exams. By far the most common technique employed is single-shot T2-weighted imaging due to its excellent tissue contrast and relative immunity to fetal motion. Despite the significant challenges involved, however, many of the other techniques commonly employed in conventional neuro- and body MRI such as T1 and T2*-weighted imaging, diffusion and perfusion weighted imaging, as well as spectroscopic methods remain of interest for fetal MR applications. An effort to understand the strengths and limitations of these basic methods within the context of fetal MRI is made in order to optimize their use and facilitate implementation of technical improvements for the further development of fetal MR imaging, both in acquisition and post-processing strategies. PMID:26225129

Accelerating Fibre Orientation Estimation from Diffusion Weighted Magnetic Resonance Imaging Using GPUs

PubMed Central

Hernández, Moisés; Guerrero, Ginés D.; Cecilia, José M.; García, José M.; Inuggi, Alberto; Jbabdi, Saad; Behrens, Timothy E. J.; Sotiropoulos, Stamatios N.

2013-01-01

With the performance of central processing units (CPUs) having effectively reached a limit, parallel processing offers an alternative for applications with high computational demands. Modern graphics processing units (GPUs) are massively parallel processors that can execute simultaneously thousands of light-weight processes. In this study, we propose and implement a parallel GPU-based design of a popular method that is used for the analysis of brain magnetic resonance imaging (MRI). More specifically, we are concerned with a model-based approach for extracting tissue structural information from diffusion-weighted (DW) MRI data. DW-MRI offers, through tractography approaches, the only way to study brain structural connectivity, non-invasively and in-vivo. We parallelise the Bayesian inference framework for the ball & stick model, as it is implemented in the tractography toolbox of the popular FSL software package (University of Oxford). For our implementation, we utilise the Compute Unified Device Architecture (CUDA) programming model. We show that the parameter estimation, performed through Markov Chain Monte Carlo (MCMC), is accelerated by at least two orders of magnitude, when comparing a single GPU with the respective sequential single-core CPU version. We also illustrate similar speed-up factors (up to 120x) when comparing a multi-GPU with a multi-CPU implementation. PMID:23658616

Is there a role for conventional MRI and MR diffusion-weighted imaging for distinction of skull base chordoma and chondrosarcoma?

PubMed

Müller, Uta; Kubik-Huch, Rahel A; Ares, Carmen; Hug, Eugen B; Löw, Roland; Valavanis, Antonios; Ahlhelm, Frank J

2016-02-01

Chordoma and chondrosarcoma are locally invasive skull base tumors with similar clinical symptoms and anatomic imaging features as reported in the literature. To determine differentiation of chordoma and chondrosarcoma of the skull base with conventional magnetic resonance imaging (cMRI) and diffusion-weighted MR imaging (DWI) in comparison to histopathological diagnosis. This retrospective study comprised 96 (chordoma, n = 64; chondrosarcoma, n = 32) patients with skull base tumors referred to the Paul Scherrer Institute (PSI) for proton therapy. cMRI signal intensities of all tumors were investigated. In addition, median apparent diffusion coefficient (ADC) values were measured in a subgroup of 19 patients (chordoma, n = 11; chondrosarcoma, n = 8). The majority 81.2% (26/32) of chondrosarcomas displayed an off-midline growth pattern, 18.8% (6/32) showed clival invasion, 18.8% (6/32) were located more centrally. Only 4.7% (3/64) of chordomas revealed a lateral clival origin. Using cMRI no significant differences in MR signal intensities were observed in contrast to significantly different ADC values (subgroup of 19/96 patients examined by DWI), with the highest mean value of 2017.2 × 10(-6 )mm(2)/s (SD, 139.9( )mm(2)/s) for chondrosarcoma and significantly lower value of 1263.5 × 10(-6 )mm(2)/s (SD, 100.2 × 10(-6 )mm(2)/s) for chordoma (P = 0.001/median test). An off-midline growth pattern can differentiate chondrosarcoma from chordoma on cMRI in a majority of patients. Additional DWI is a promising tool for the differentiation of these skull base tumors. © The Foundation Acta Radiologica 2015.

Brain Abnormalities in Congenital Fibrosis of the Extraocular Muscles Type 1: A Multimodal MRI Imaging Study

PubMed Central

Wu, Shaoqin; Lv, Bin; Wang, Zhenchang; Xian, Junfang; Sabel, Bernhard A.; He, Huiguang; Jiao, Yonghong

2015-01-01

Purpose To explore the possible brain structural and functional alterations in congenital fibrosis of extraocular muscles type 1 (CFEOM1) patients using multimodal MRI imaging. Methods T1-weighted, diffusion tensor images and functional MRI data were obtained from 9 KIF21A positive patients and 19 age- and gender- matched healthy controls. Voxel based morphometry and tract based spatial statistics were applied to the T1-weighted and diffusion tensor images, respectively. Amplitude of low frequency fluctuations and regional homogeneity were used to process the functional MRI data. We then compared these multimodal characteristics between CFEOM1 patients and healthy controls. Results Compared with healthy controls, CFEOM1 patients demonstrated increased grey matter volume in bilateral frontal orbital cortex and in the right temporal pole. No diffusion indices changes were detected, indicating unaffected white matter microstructure. In addition, from resting state functional MRI data, trend of amplitude of low-frequency fluctuations increases were noted in the right inferior parietal lobe and in the right frontal cortex, and a trend of ReHo increase (p<0.001 uncorrected) in the left precentral gyrus, left orbital frontal cortex, temporal pole and cingulate gyrus. Conclusions CFEOM1 patients had structural and functional changes in grey matter, but the white matter was unaffected. These alterations in the brain may be due to the abnormality of extraocular muscles and their innervating nerves. Future studies should consider the possible correlations between brain morphological/functional findings and clinical data, especially pertaining to eye movements, to obtain more precise answers about the role of brain area changes and their functional consequence in CFEOM1. PMID:26186732

Characterizing Microstructural Tissue Properties in Multiple Sclerosis with Diffusion MRI at 7 T and 3 T: The Impact of the Experimental Design.

PubMed

De Santis, Silvia; Bastiani, Matteo; Droby, Amgad; Kolber, Pierre; Zipp, Frauke; Pracht, Eberhard; Stoecker, Tony; Groppa, Sergiu; Roebroeck, Alard

2018-04-07

The recent introduction of advanced magnetic resonance (MR) imaging techniques to characterize focal and global degeneration in multiple sclerosis (MS), like the Composite Hindered and Restricted Model of Diffusion, or CHARMED, diffusional kurtosis imaging (DKI) and Neurite Orientation Dispersion and Density Imaging (NODDI) made available new tools to image axonal pathology non-invasively in vivo. These methods already showed greater sensitivity and specificity compared to conventional diffusion tensor-based metrics (e.g., fractional anisotropy), overcoming some of its limitations. While previous studies uncovered global and focal axonal degeneration in MS patients compared to healthy controls, here our aim is to investigate and compare different diffusion MRI acquisition protocols in their ability to highlight microstructural differences between MS and control tissue over several much used models. For comparison, we contrasted the ability of fractional anisotropy measurements to uncover differences between lesion, normal-appearing white matter (WM), gray matter and healthy tissue under the same imaging protocols. We show that: (1) focal and diffuse differences in several microstructural parameters are observed under clinical settings; (2) advanced models (CHARMED, DKI and NODDI) have increased specificity and sensitivity to neurodegeneration when compared to fractional anisotropy measurements; and (3) both high (3 T) and ultra-high fields (7 T) are viable options for imaging tissue change in MS lesions and normal appearing WM, while higher b-values are less beneficial under the tested short-time (10 min acquisition) conditions. Copyright © 2018 The Author(s). Published by Elsevier Ltd.. All rights reserved.

The role of tissue microstructure and water exchange in biophysical modelling of diffusion in white matter.

PubMed

Nilsson, Markus; van Westen, Danielle; Ståhlberg, Freddy; Sundgren, Pia C; Lätt, Jimmy

2013-08-01

Biophysical models that describe the outcome of white matter diffusion MRI experiments have various degrees of complexity. While the simplest models assume equal-sized and parallel axons, more elaborate ones may include distributions of axon diameters and axonal orientation dispersions. These microstructural features can be inferred from diffusion-weighted signal attenuation curves by solving an inverse problem, validated in several Monte Carlo simulation studies. Model development has been paralleled by microscopy studies of the microstructure of excised and fixed nerves, confirming that axon diameter estimates from diffusion measurements agree with those from microscopy. However, results obtained in vivo are less conclusive. For example, the amount of slowly diffusing water is lower than expected, and the diffusion-encoded signal is apparently insensitive to diffusion time variations, contrary to what may be expected. Recent understandings of the resolution limit in diffusion MRI, the rate of water exchange, and the presence of microscopic axonal undulation and axonal orientation dispersions may, however, explain such apparent contradictions. Knowledge of the effects of biophysical mechanisms on water diffusion in tissue can be used to predict the outcome of diffusion tensor imaging (DTI) and of diffusion kurtosis imaging (DKI) studies. Alterations of DTI or DKI parameters found in studies of pathologies such as ischemic stroke can thus be compared with those predicted by modelling. Observations in agreement with the predictions strengthen the credibility of biophysical models; those in disagreement could provide clues of how to improve them. DKI is particularly suited for this purpose; it is performed using higher b-values than DTI, and thus carries more information about the tissue microstructure. The purpose of this review is to provide an update on the current understanding of how various properties of the tissue microstructure and the rate of water exchange between microenvironments are reflected in diffusion MRI measurements. We focus on the use of biophysical models for extracting tissue-specific parameters from data obtained with single PGSE sequences on clinical MRI scanners, but results obtained with animal MRI scanners are also considered. While modelling of white matter is the central theme, experiments on model systems that highlight important aspects of the biophysical models are also reviewed.

Reduced acoustic noise in diffusion tensor imaging on a compact MRI system.

PubMed

Tan, Ek T; Hardy, Christopher J; Shu, Yunhong; In, Myung-Ho; Guidon, Arnaud; Huston, John; Bernstein, Matt A; K F Foo, Thomas

2018-06-01

To investigate the feasibility of substantially reducing acoustic noise while performing diffusion tensor imaging (DTI) on a compact 3T (C3T) MRI scanner equipped with a 42-cm inner-diameter asymmetric gradient. A-weighted acoustic measurements were made using 10 mT/m-amplitude sinusoidal waveforms, corresponding to echo-planar imaging (EPI) echo spacing of 0.25 to 5.0 ms, on a conventional, whole-body 3T MRI and on the C3T. Acoustic measurements of DTI with trapezoidal EPI waveforms were then made at peak gradient performance on the C3T (80 mT/m amplitude, 700 T/m/s slew rate) and at derated performance (33 mT/m, 10 to 50 T/m/s) for acoustic noise reduction. DTI was acquired in two different phantoms and in seven human subjects, with and without gradient-derating corresponding to multi- and single-shot acquisitions, respectively. Sinusoidal waveforms on the C3T were quieter by 8.5 to 15.6 A-weighted decibels (dBA) on average as compared to the whole-body MRI. The derated multishot DTI acquisition noise level was only 8.7 dBA (at 13 T/m/s slew rate) above ambient, and was quieter than non-derated, single-shot DTI by 22.3 dBA; however, the scan time was almost quadrupled. Although derating resulted in negligible diffusivity differences in the phantoms, small biases in diffusivity measurements were observed in human subjects (apparent diffusion coefficient = +9.3 ± 8.8%, fractional anisotropy = +3.2 ± 11.2%, radial diffusivity = +9.4 ± 16.8%, parallel diffusivity = +10.3 ± 8.4%). The feasibility of achieving reduced acoustic noise levels with whole-brain DTI on the C3T MRI was demonstrated. Magn Reson Med 79:2902-2911, 2018. © 2017 International Society for Magnetic Resonance in Medicine. © 2017 International Society for Magnetic Resonance in Medicine.

Focal Cortical Dysplasia (FCD) lesion analysis with complex diffusion approach.

PubMed

Rajan, Jeny; Kannan, K; Kesavadas, C; Thomas, Bejoy

2009-10-01

Identification of Focal Cortical Dysplasia (FCD) can be difficult due to the subtle MRI changes. Though sequences like FLAIR (fluid attenuated inversion recovery) can detect a large majority of these lesions, there are smaller lesions without signal changes that can easily go unnoticed by the naked eye. The aim of this study is to improve the visibility of focal cortical dysplasia lesions in the T1 weighted brain MRI images. In the proposed method, we used a complex diffusion based approach for calculating the FCD affected areas. Based on the diffused image and thickness map, a complex map is created. From this complex map; FCD areas can be easily identified. MRI brains of 48 subjects selected by neuroradiologists were given to computer scientists who developed the complex map for identifying the cortical dysplasia. The scientists were blinded to the MRI interpretation result of the neuroradiologist. The FCD could be identified in all the patients in whom surgery was done, however three patients had false positive lesions. More lesions were identified in patients in whom surgery was not performed and lesions were seen in few of the controls. These were considered as false positive. This computer aided detection technique using complex diffusion approach can help detect focal cortical dysplasia in patients with epilepsy.

Non-invasive high-resolution tracking of human neuronal pathways: diffusion tensor imaging at 7T with 1.2 mm isotropic voxel size

NASA Astrophysics Data System (ADS)

Lützkendorf, Ralf; Hertel, Frank; Heidemann, Robin; Thiel, Andreas; Luchtmann, Michael; Plaumann, Markus; Stadler, Jörg; Baecke, Sebastian; Bernarding, Johannes

2013-03-01

Diffusion tensor imaging (DTI) allows characterizing and exploiting diffusion anisotropy effects, thereby providing important details about tissue microstructure. A major application in neuroimaging is the so-called fiber tracking where neuronal connections between brain regions are determined non-invasively by DTI. Combining these neural pathways within the human brain with the localization of activated brain areas provided by functional MRI offers important information about functional connectivity of brain regions. However, DTI suffers from severe signal reduction due to the diffusion-weighting. Ultra-high field (UHF) magnetic resonance imaging (MRI) should therefore be advantageous to increase the intrinsic signal-to-noise ratio (SNR). This in turn enables to acquire high quality data with increased resolution, which is beneficial for tracking more complex fiber structures. However, UHF MRI imposes some difficulties mainly due to the larger B1 inhomogeneity compared to 3T MRI. We therefore optimized the parameters to perform DTI at a 7 Tesla whole body MR scanner equipped with a high performance gradient system and a 32-channel head receive coil. A Stesjkal Tanner spin-echo EPI sequence was used, to acquire 110 slices with an isotropic voxel-size of 1.2 mm covering the whole brain. 60 diffusion directions were scanned which allows calculating the principal direction components of the diffusion vector in each voxel. The results prove that DTI can be performed with high quality at UHF and that it is possible to explore the SNT benefit of the higher field strength. Combining UHF fMRI data with UHF DTI results will therefore be a major step towards better neuroimaging methods.

[The Role of Imaging in Central Nervous System Infections].

PubMed

Yokota, Hajime; Tazoe, Jun; Yamada, Kei

2015-07-01

Many infections invade the central nervous system. Magnetic resonance imaging (MRI) is the main tool that is used to evaluate infectious lesions of the central nervous system. The useful sequences on MRI are dependent on the locations, such as intra-axial, extra-axial, and spinal cord. For intra-axial lesions, besides the fundamental sequences, including T1-weighted images, T2-weighted images, and fluid-attenuated inversion recovery (FLAIR) images, advanced sequences, such as diffusion-weighted imaging, diffusion tensor imaging, susceptibility-weighted imaging, and MR spectroscopy, can be applied. They are occasionally used as determinants for quick and correct diagnosis. For extra-axial lesions, understanding the differences among 2D-conventional T1-weighted images, 2D-fat-saturated T1-weighted images, 3D-Spin echo sequences, and 3D-Gradient echo sequence after the administration of gadolinium is required to avoid wrong interpretations. FLAIR plus gadolinium is a useful tool for revealing abnormal enhancement on the brain surface. For the spinal cord, the sequences are limited. Evaluating the distribution and time course of the spinal cord are essential for correct diagnoses. We summarize the role of imaging in central nervous system infections and show the pitfalls, key points, and latest information in them on clinical practices.

Low-field and high-field magnetic resonance contrast imaging of magnetoferritin as a pathological model system of iron accumulation

NASA Astrophysics Data System (ADS)

Strbak, Oliver; Balejcikova, Lucia; Baciak, Ladislav; Kovac, Jozef; Masarova-Kozelova, Marta; Krafcik, Andrej; Dobrota, Dusan; Kopcansky, Peter

2017-09-01

Various pathological processes including neurodegenerative disorders are associated with the accumulation of iron, while it is believed that a precursor of iron accumulation is ferritin. Physiological ferritin is due to low relaxivity, which results in only weak detection by magnetic resonance imaging (MRI) techniques. On the other hand, pathological ferritin is associated with disrupted iron homeostasis and structural changes in the mineral core, and should increase the hypointensive artefacts in MRI. On the basis of recent findings in respect to the pathological ferritin structure, we prepared the magnetoferritin particles as a possible pathological ferritin model system. The particles were characterised with dynamic light scattering, as well as with superconducting quantum interference device measurements. With the help of low-field (0.2 T) and high-field (4.7 T) MRI standard T 2-weighted protocols we found that it is possible to clearly distinguish between native ferritin as a physiological model system, and magnetoferritin as a pathological model system. Surprisingly, the T 2-weighted short TI inversion recovery protocol at low-field system showed the optimum contrast differentiation. Such findings are highly promising for exploiting the use of iron accumulation as a noninvasive diagnostics tool of pathological processes, where the magnetoferritin particles could be utilised as MRI iron quantification calibration samples.

The Alzheimer's Disease Neuroimaging Initiative (ADNI): MRI Methods

PubMed Central

Jack, Clifford R.; Bernstein, Matt A.; Fox, Nick C.; Thompson, Paul; Alexander, Gene; Harvey, Danielle; Borowski, Bret; Britson, Paula J.; Whitwell, Jennifer L.; Ward, Chadwick; Dale, Anders M.; Felmlee, Joel P.; Gunter, Jeffrey L.; Hill, Derek L.G.; Killiany, Ron; Schuff, Norbert; Fox-Bosetti, Sabrina; Lin, Chen; Studholme, Colin; DeCarli, Charles S.; Krueger, Gunnar; Ward, Heidi A.; Metzger, Gregory J.; Scott, Katherine T.; Mallozzi, Richard; Blezek, Daniel; Levy, Joshua; Debbins, Josef P.; Fleisher, Adam S.; Albert, Marilyn; Green, Robert; Bartzokis, George; Glover, Gary; Mugler, John; Weiner, Michael W.

2008-01-01

The Alzheimer's Disease Neuroimaging Initiative (ADNI) is a longitudinal multisite observational study of healthy elders, mild cognitive impairment (MCI), and Alzheimer's disease. Magnetic resonance imaging (MRI), (18F)-fluorode-oxyglucose positron emission tomography (FDG PET), urine serum, and cerebrospinal fluid (CSF) biomarkers, as well as clinical/psychometric assessments are acquiredat multiple time points. All data will be cross-linked and made available to the general scientific community. The purpose of this report is to describe the MRI methods employed in ADNI. The ADNI MRI core established specifications thatguided protocol development. A major effort was devoted toevaluating 3D T1-weighted sequences for morphometric analyses. Several options for this sequence were optimized for the relevant manufacturer platforms and then compared in a reduced-scale clinical trial. The protocol selected for the ADNI study includes: back-to-back 3D magnetization prepared rapid gradient echo (MP-RAGE) scans; B1-calibration scans when applicable; and an axial proton density-T2 dual contrast (i.e., echo) fast spin echo/turbo spin echo (FSE/TSE) for pathology detection. ADNI MRI methods seek to maximize scientific utility while minimizing the burden placed on participants. The approach taken in ADNI to standardization across sites and platforms of the MRI protocol, postacquisition corrections, and phantom-based monitoring of all scanners could be used as a model for other multisite trials. PMID:18302232

The Age-ility Project (Phase 1): Structural and functional imaging and electrophysiological data repository.

PubMed

Karayanidis, Frini; Keuken, Max C; Wong, Aaron; Rennie, Jaime L; de Hollander, Gilles; Cooper, Patrick S; Ross Fulham, W; Lenroot, Rhoshel; Parsons, Mark; Phillips, Natalie; Michie, Patricia T; Forstmann, Birte U

2016-01-01

Our understanding of the complex interplay between structural and functional organisation of brain networks is being advanced by the development of novel multi-modal analyses approaches. The Age-ility Project (Phase 1) data repository offers open access to structural MRI, diffusion MRI, and resting-state fMRI scans, as well as resting-state EEG recorded from the same community participants (n=131, 15-35 y, 66 male). Raw imaging and electrophysiological data as well as essential demographics are made available via the NITRC website. All data have been reviewed for artifacts using a rigorous quality control protocol and detailed case notes are provided. Copyright © 2015. Published by Elsevier Inc.

Sensitivity and specificity of univariate MRI analysis of experimentally degraded cartilage under clinical imaging conditions.

PubMed

Lukas, Vanessa A; Fishbein, Kenneth W; Reiter, David A; Lin, Ping-Chang; Schneider, Erika; Spencer, Richard G

2015-07-01

To evaluate the sensitivity and specificity of classification of pathomimetically degraded bovine nasal cartilage at 3 Tesla and 37°C using univariate MRI measurements of both pure parameter values and intensities of parameter-weighted images. Pre- and posttrypsin degradation values of T1 , T2 , T2 *, magnetization transfer ratio (MTR), and apparent diffusion coefficient (ADC), and corresponding weighted images, were analyzed. Classification based on the Euclidean distance was performed and the quality of classification was assessed through sensitivity, specificity and accuracy (ACC). The classifiers with the highest accuracy values were ADC (ACC = 0.82 ± 0.06), MTR (ACC = 0.78 ± 0.06), T1 (ACC = 0.99 ± 0.01), T2 derived from a three-dimensional (3D) spin-echo sequence (ACC = 0.74 ± 0.05), and T2 derived from a 2D spin-echo sequence (ACC = 0.77 ± 0.06), along with two of the diffusion-weighted signal intensities (b = 333 s/mm(2) : ACC = 0.80 ± 0.05; b = 666 s/mm(2) : ACC = 0.85 ± 0.04). In particular, T1 values differed substantially between the groups, resulting in atypically high classification accuracy. The second-best classifier, diffusion weighting with b = 666 s/mm(2) , as well as all other parameters evaluated, exhibited substantial overlap between pre- and postdegradation groups, resulting in decreased accuracies. Classification according to T1 values showed excellent test characteristics (ACC = 0.99), with several other parameters also showing reasonable performance (ACC > 0.70). Of these, diffusion weighting is particularly promising as a potentially practical clinical modality. As in previous work, we again find that highly statistically significant group mean differences do not necessarily translate into accurate clinical classification rules. © 2014 Wiley Periodicals, Inc.

Principles of diffusion kurtosis imaging and its role in early diagnosis of neurodegenerative disorders.

PubMed

Arab, Anas; Wojna-Pelczar, Anna; Khairnar, Amit; Szabó, Nikoletta; Ruda-Kucerova, Jana

2018-05-01

Pathology of neurodegenerative diseases can be correlated with intra-neuronal as well as extracellular changes which lead to neuronal degeneration. The central nervous system (CNS) is a complex structure comprising of many biological barriers. These microstructural barriers might be affected by a variety of pathological processes. Specifically, changes in the brain tissue's microstructure affect the diffusion of water which can be assessed non-invasively by diffusion weighted (DW) magnetic resonance imaging (MRI) techniques. Diffusion tensor imaging (DTI) is a diffusion MRI technique that considers diffusivity as a Gaussian process, i.e. does not account for any diffusion hindrance. However, environment of the brain tissues is characterized by a non-Gaussian diffusion. Therefore, diffusion kurtosis imaging (DKI) was developed as an extension of DTI method in order to quantify the non-Gaussian distribution of water diffusion. This technique represents a promising approach for early diagnosis of neurodegenerative diseases when the neurodegenerative process starts. Hence, the purpose of this article is to summarize the ongoing clinical and preclinical research on Parkinson's, Alzheimer's and Huntington diseases, using DKI and to discuss the role of this technique as an early stage biomarker of neurodegenerative conditions. Copyright © 2018 Elsevier Inc. All rights reserved.

Multiparametric Magnetic Resonance Imaging of the Prostate for Tumour Detection and Local Staging: Imaging in 1.5T and Histopathologic Correlation.

PubMed

Loggitsi, Dimitra; Gyftopoulos, Anastasios; Economopoulos, Nikolaos; Apostolaki, Aikaterini; Kalogeropoulos, Theodoros; Thanos, Anastasios; Alexopoulou, Efthimia; Kelekis, Nikolaos L

2017-11-01

The study sought to prospectively evaluate which technique among T2-weighted images, dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI), diffusion-weighted (DW) MRI, or a combination of the 2, is best suited for prostate cancer detection and local staging. Twenty-seven consecutive patients with biopsy-proven adenocarcinoma of the prostate underwent MRI on a 1.5T scanner with a surface phased-array coil prior radical prostatectomy. Combined anatomical and functional imaging was performed with the use of T2-weighted sequences, DCE MRI, and DW MRI. We compared the imaging results with whole mount histopathology. For the multiparametric approach, significantly higher sensitivity values, that is, 53% (95% confidence interval [CI]: 41.0-64.1) were obtained as compared with each modality alone or any combination of the 3 modalities (P < .05). The specificity for this multiparametric approach, being 90.3% (95% CI: 86.3-93.3) was not significantly higher (P < .05) as compared with the values of the combination of T2+DCE MRI, DW+DCE MRI, or DCE MRI alone. Among the 3 techniques, DCE had the best performance for tumour detection in both the peripheral and the transition zone. High negative predictive value rates (>86%) were obtained for both tumour detection and local staging. The combination of T2-weighted sequences, DCE MRI, and DW MRI yields higher diagnostic performance for tumour detection and local staging than can any of these techniques alone or even any combination of them. Copyright © 2017 Canadian Association of Radiologists. Published by Elsevier Inc. All rights reserved.

Simultaneous whole body 18F-fluorodeoxyglucose positron emission tomography magnetic resonance imaging for evaluation of pediatric cancer: Preliminary experience and comparison with 18F-fluorodeoxyglucose positron emission tomography computed tomography

PubMed Central

Pugmire, Brian S; Guimaraes, Alexander R; Lim, Ruth; Friedmann, Alison M; Huang, Mary; Ebb, David; Weinstein, Howard; Catalano, Onofrio A; Mahmood, Umar; Catana, Ciprian; Gee, Michael S

2016-01-01

AIM: To describe our preliminary experience with simultaneous whole body 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography and magnetic resonance imaging (PET-MRI) in the evaluation of pediatric oncology patients. METHODS: This prospective, observational, single-center study was Health Insurance Portability and Accountability Act-compliant, and institutional review board approved. To be eligible, a patient was required to: (1) have a known or suspected cancer diagnosis; (2) be under the care of a pediatric hematologist/oncologist; and (3) be scheduled for clinically indicated 18F-FDG positron emission tomography-computed tomography (PET-CT) examination at our institution. Patients underwent PET-CT followed by PET-MRI on the same day. PET-CT examinations were performed using standard department protocols. PET-MRI studies were acquired with an integrated 3 Tesla PET-MRI scanner using whole body T1 Dixon, T2 HASTE, EPI diffusion-weighted imaging (DWI) and STIR sequences. No additional radiotracer was given for the PET-MRI examination. Both PET-CT and PET-MRI examinations were reviewed by consensus by two study personnel. Test performance characteristics of PET-MRI, for the detection of malignant lesions, including FDG maximum standardized uptake value (SUVmax) and minimum apparent diffusion coefficient (ADCmin), were calculated on a per lesion basis using PET-CT as a reference standard. RESULTS: A total of 10 whole body PET-MRI exams were performed in 7 pediatric oncology patients. The mean patient age was 16.1 years (range 12-19 years) including 6 males and 1 female. A total of 20 malignant and 21 benign lesions were identified on PET-CT. PET-MRI SUVmax had excellent correlation with PET-CT SUVmax for both benign and malignant lesions (R = 0.93). PET-MRI SUVmax > 2.5 had 100% accuracy for discriminating benign from malignant lesions using PET-CT reference. Whole body DWI was also evaluated: the mean ADCmin of malignant lesions (780.2 + 326.6) was significantly lower than that of benign lesions (1246.2 + 417.3; P = 0.0003; Student’s t test). A range of ADCmin thresholds for malignancy were evaluated, from 0.5-1.5 × 10-3 mm2/s. The 1.0 × 10-3 ADCmin threshold performed best compared with PET-CT reference (68.3% accuracy). However, the accuracy of PET-MRI SUVmax was significantly better than ADCmin for detecting malignant lesions compared with PET-CT reference (P < 0.0001; two-tailed McNemar’s test). CONCLUSION: These results suggest a clinical role for simultaneous whole body PET-MRI in evaluating pediatric cancer patients. PMID:27028112

Simultaneous whole body (18)F-fluorodeoxyglucose positron emission tomography magnetic resonance imaging for evaluation of pediatric cancer: Preliminary experience and comparison with (18)F-fluorodeoxyglucose positron emission tomography computed tomography.

PubMed

Pugmire, Brian S; Guimaraes, Alexander R; Lim, Ruth; Friedmann, Alison M; Huang, Mary; Ebb, David; Weinstein, Howard; Catalano, Onofrio A; Mahmood, Umar; Catana, Ciprian; Gee, Michael S

2016-03-28

To describe our preliminary experience with simultaneous whole body (18)F-fluorodeoxyglucose ((18)F-FDG) positron emission tomography and magnetic resonance imaging (PET-MRI) in the evaluation of pediatric oncology patients. This prospective, observational, single-center study was Health Insurance Portability and Accountability Act-compliant, and institutional review board approved. To be eligible, a patient was required to: (1) have a known or suspected cancer diagnosis; (2) be under the care of a pediatric hematologist/oncologist; and (3) be scheduled for clinically indicated (18)F-FDG positron emission tomography-computed tomography (PET-CT) examination at our institution. Patients underwent PET-CT followed by PET-MRI on the same day. PET-CT examinations were performed using standard department protocols. PET-MRI studies were acquired with an integrated 3 Tesla PET-MRI scanner using whole body T1 Dixon, T2 HASTE, EPI diffusion-weighted imaging (DWI) and STIR sequences. No additional radiotracer was given for the PET-MRI examination. Both PET-CT and PET-MRI examinations were reviewed by consensus by two study personnel. Test performance characteristics of PET-MRI, for the detection of malignant lesions, including FDG maximum standardized uptake value (SUVmax) and minimum apparent diffusion coefficient (ADCmin), were calculated on a per lesion basis using PET-CT as a reference standard. A total of 10 whole body PET-MRI exams were performed in 7 pediatric oncology patients. The mean patient age was 16.1 years (range 12-19 years) including 6 males and 1 female. A total of 20 malignant and 21 benign lesions were identified on PET-CT. PET-MRI SUVmax had excellent correlation with PET-CT SUVmax for both benign and malignant lesions (R = 0.93). PET-MRI SUVmax > 2.5 had 100% accuracy for discriminating benign from malignant lesions using PET-CT reference. Whole body DWI was also evaluated: the mean ADCmin of malignant lesions (780.2 + 326.6) was significantly lower than that of benign lesions (1246.2 + 417.3; P = 0.0003; Student's t test). A range of ADCmin thresholds for malignancy were evaluated, from 0.5-1.5 × 10(-3) mm(2)/s. The 1.0 × 10(-3) ADCmin threshold performed best compared with PET-CT reference (68.3% accuracy). However, the accuracy of PET-MRI SUVmax was significantly better than ADCmin for detecting malignant lesions compared with PET-CT reference (P < 0.0001; two-tailed McNemar's test). These results suggest a clinical role for simultaneous whole body PET-MRI in evaluating pediatric cancer patients.

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

PubMed Central

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

Diffusion heterogeneity tensor MRI (?-Dti): mathematics and initial applications in spinal cord regeneration after trauma - biomed 2009.

PubMed

Ellington, Benjamin M; Schmit, Brian D; Gourab, Krishnaj; Sieber-Blum, Maya; Hu, Yao F; Schmainda, Kathleen M

2009-01-01

Diffusion weighted magnetic resonance imaging (DWI) is a powerful tool for evaluation of microstructural anomalies in numerous central nervous system pathologies. Diffusion tensor imaging (DTI) allows for the magnitude and direction of water self diffusion to be estimated by sampling the apparent diffusion coefficient (ADC) in various directions. Clinical DWI and DTI performed at a single level of diffusion weighting, however, does not allow for multiple diffusion compartments to be elicited. Furthermore, assumptions made regarding the precise number of diffusion compartments intrinsic to the tissue of interest have resulted in a lack of consensus between investigations. To overcome these challenges, a stretched-exponential model of diffusion was applied to examine the diffusion coefficient and "heterogeneity index" within highly compartmentalized brain tumors. The purpose of the current study is to expand on the stretched-exponential model of diffusion to include directionality of both diffusion heterogeneity and apparent diffusion coefficient. This study develops the mathematics of this new technique along with an initial application in quantifying spinal cord regeneration following acute injection of epidermal neural crest stem cell (EPI-NCSC) grafts.

Apparent Diffusion Coefficient and Dynamic Contrast-Enhanced Magnetic Resonance Imaging in Pancreatic Cancer: Characteristics and Correlation With Histopathologic Parameters.

PubMed

Ma, Wanling; Li, Na; Zhao, Weiwei; Ren, Jing; Wei, Mengqi; Yang, Yong; Wang, Yingmei; Fu, Xin; Zhang, Zhuoli; Larson, Andrew C; Huan, Yi

2016-01-01

To clarify diffusion and perfusion abnormalities and evaluate correlation between apparent diffusion coefficient (ADC), MR perfusion and histopathologic parameters of pancreatic cancer (PC). Eighteen patients with PC underwent diffusion-weighted imaging and dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI). Parameters of DCE-MRI and ADC of cancer and non-cancerous tissue were compared. Correlation between the rate constant that represents transfer of contrast agent from the arterial blood into the extravascular extracellular space (K, volume of the extravascular extracellular space per unit volume of tissue (Ve), and ADC of PC and histopathologic parameters were analyzed. The rate constant that represents transfer of contrast agent from the extravascular extracellular space into blood plasma, K, tissue volume fraction occupied by vascular space, and ADC of PC were significantly lower than nontumoral pancreases. Ve of PC was significantly higher than that of nontumoral pancreas. Apparent diffusion coefficient and K values of PC were negatively correlated to fibrosis content and fibroblast activation protein staining score. Fibrosis content was positively correlated to Ve. Apparent diffusion coefficient values and parameters of DCE-MRI can differentiate PC from nontumoral pancreases. There are correlations between ADC, K, Ve, and fibrosis content of PC. Fibroblast activation protein staining score of PC is negatively correlated to ADC and K. Apparent diffusion coefficient, K, and Ve may be feasible to predict prognosis of PC.

Relationship between diffusivity of water molecules inside hydrating tablets and their drug release behavior elucidated by magnetic resonance imaging.

PubMed

Kikuchi, Shingo; Onuki, Yoshinori; Kuribayashi, Hideto; Takayama, Kozo

2012-01-01

We reported previously that sustained release matrix tablets showed zero-order drug release without being affected by pH change. To understand drug release mechanisms more fully, we monitored the swelling and erosion of hydrating tablets using magnetic resonance imaging (MRI). Three different types of tablets comprised of polyion complex-forming materials and a hydroxypropyl methylcellulose (HPMC) were used. Proton density- and diffusion-weighted images of the hydrating tablets were acquired at intervals. Furthermore, apparent self-diffusion coefficient maps were generated from diffusion-weighted imaging to evaluate the state of hydrating tablets. Our findings indicated that water penetration into polyion complex tablets was faster than that into HPMC matrix tablets. In polyion complex tablets, water molecules were dispersed homogeneously and their diffusivity was relatively high, whereas in HPMC matrix tablets, water molecule movement was tightly restricted within the gel. An optimal tablet formulation determined in a previous study had water molecule penetration and diffusivity properties that appeared intermediate to those of polyion complex and HPMC matrix tablets; water molecules were capable of penetrating throughout the tablets and relatively high diffusivity was similar to that in the polyion complex tablet, whereas like the HPMC matrix tablet, it was well swollen. This study succeeded in characterizing the tablet hydration process. MRI provides profound insight into the state of water molecules in hydrating tablets; thus, it is a useful tool for understanding drug release mechanisms at a molecular level.

Novel Imaging Contrast Methods for Hyperpolarized 13 C Magnetic Resonance Imaging

NASA Astrophysics Data System (ADS)

Reed, Galen Durant

Magnetic resonance imaging using hyperpolarized 13C-labeled small molecules has emerged as an extremely powerful tool for the in vivo monitoring of perfusion and metabolism. This work presents methods for improved imaging, parameter mapping, and image contrast generation for in vivo hyperpolarized 13C MRI. Angiography using hyperpolarized urea was greatly improved with a highly T2-weighted acquisition in combination with 15N labeling of the urea amide groups. This is due to the fact that the T2 of [13C]urea is strongly limited by the scalar coupling to the neighboring quadrupolar 14N. The long in vivo T2 values of [13C, 15N2]urea were utilized for sub-millimeter projection angiography using a contrast agent that could be safely injected in concentrations of 10-100 mM while still tolerated in patients with renal insufficiency. This study also presented the first method for in vivo T2 mapping of hyperpolarized 13C compounds. The in vivo T2 of urea was short in the blood and long within the kidneys. This persistent signal component was isolated to the renal filtrate, thus enabling for the first time direct detection of an imaging contrast agent undergoing glomerular filtration. While highly T2-weighted acquisitions select for molecules with short rotational correlation times, high diffusion weighting selects for those with the long translational correlation times. A specialized spin-echo EPI sequence was developed in order to generate highly diffusion-weighted hyperpolarized 13C images on a clinical MRI system operating within clinical peak- RF and gradient amplitude constraints. Low power adiabatic spin echo pulses were developed in order to generate a sufficiently large refocused bandwidth while maintaining low nominal power. This diffusion weighted acquisition gave enhanced tumor contrast-to-noise ratio when imaging [1-13C]lactate after infusion of [1-13C]pyruvate. Finally, the first in-man hyperpolarized 13C MRI clinical trial is discussed.

Implementation and assessment of diffusion-weighted partial Fourier readout-segmented echo-planar imaging.

PubMed

Frost, Robert; Porter, David A; Miller, Karla L; Jezzard, Peter

2012-08-01

Single-shot echo-planar imaging has been used widely in diffusion magnetic resonance imaging due to the difficulties in correcting motion-induced phase corruption in multishot data. Readout-segmented EPI has addressed the multishot problem by introducing a two-dimensional nonlinear navigator correction with online reacquisition of uncorrectable data to enable acquisition of high-resolution diffusion data with reduced susceptibility artifact and T*(2) blurring. The primary shortcoming of readout-segmented EPI in its current form is its long acquisition time (longer than similar resolution single-shot echo-planar imaging protocols by approximately the number of readout segments), which limits the number of diffusion directions. By omitting readout segments at one side of k-space and using partial Fourier reconstruction, readout-segmented EPI imaging times could be reduced. In this study, the effects of homodyne and projection onto convex sets reconstructions on estimates of the fractional anisotropy, mean diffusivity, and diffusion orientation in fiber tracts and raw T(2)- and trace-weighted signal are compared, along with signal-to-noise ratio results. It is found that projections onto convex sets reconstruction with 3/5 segments in a 2 mm isotropic diffusion tensor image acquisition and 9/13 segments in a 0.9 × 0.9 × 4.0 mm(3) diffusion-weighted image acquisition provide good fidelity relative to the full k-space parameters. This allows application of readout-segmented EPI to tractography studies, and clinical stroke and oncology protocols. Copyright © 2011 Wiley-Liss, Inc.

SU-E-P-33: Critical Role of T2-Weighted Imaging Combined with Diffusion-Weighted Imaging of MRI in Diagnosis of Loco-Regional Recurrent Esophageal Cancer After Radical Surgery

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

Deng, G; Qiao, L; Liang, N

Purpose: We perform this study to investigate the diagnostic efficacy of T2-weighted MRI (T2WI) and diffusion-weighted MRI (DWI) in confirming local relapses of esophageal cancer in patients highly suspected of recurrence after eradicating surgery. Methods: Forty-two postoperative esophageal cancer patients with clinical suspicions of cancer recurrence underwent 3.0T MRI applying axial, coronal, sagittal T2WI and axial DWI sequences. Two experienced radiologists (R1 and R2) both used two methods (T2WI, T2WI+DWI) to observe the images, and graded the patients ranging from 1 to 5 to represent severity of the disease based on visual signal intensity (patients equal to or more thanmore » grade 3 was confirmed as recurrent disease) Results: 27/42patients were verified of recurrent disease by pathologic findings and/or imaging findings during follow-up. The sensitivity, specificity and accuracy of R1 applying T2WI+DWI are 96%, 87% and 93% versus 81%, 80% and 77% on T2WI, these figures by R2 were 96%, 93% and 95% versus 89%, 93% and 90%. The receiver operating curve (ROC) analyses suggest that both of the two readers can obtain better accuracy when adding DWI to T2WI compared with T2WI alone. Kappa test between R1 and R2 indicates excellent inter-observer agreement on T2WI+DWI. Conclusion: Standard T2WI in combination DWI can achieve better accuracy than T2WI alone in diagnosing local recurrence of esophageal cancer, and improve consistency between different readers.« less

MRI assessment of the thigh musculature in dermatomyositis and healthy subjects using diffusion tensor imaging, intravoxel incoherent motion and dynamic DTI.

PubMed

Sigmund, E E; Baete, S H; Luo, T; Patel, K; Wang, D; Rossi, I; Duarte, A; Bruno, M; Mossa, D; Femia, A; Ramachandran, S; Stoffel, D; Babb, J S; Franks, A; Bencardino, J

2018-06-04

Dermatomyositis (DM) is an idiopathic inflammatory myopathy involving severe debilitation in need of diagnostics. We evaluated the proximal lower extremity musculature with diffusion tensor imaging (DTI), intravoxel incoherent motion (IVIM) and dynamic DTI in DM patients and controls and compared with standard clinical workup.  METHODS: In this IRB-approved, HIPAA-compliant study with written informed consent, anatomical, Dixon fat/water and diffusion imaging were collected in bilateral thigh MRI of 22 controls and 27 DM patients in a 3T scanner. Compartments were scored on T1/T2 scales. Single voxel dynamic DTI metrics in quadriceps before and after 3-min leg exercise were measured. Spearman rank correlation and mixed model analysis of variance/covariance (ANOVA/ANCOVA) were used to correlate with T1 and T2 scores and to compare patients with controls. DM patients showed significantly lower pseudo-diffusion and volume in quadriceps than controls. All subjects showed significant correlation between T1 score and signal-weighted fat fraction; tissue diffusion and pseudo-diffusion varied significantly with T1 and T2 score in patients. Radial and mean diffusion exercise response in patients was significantly higher than controls. Static and dynamic diffusion imaging metrics show correlation with conventional imaging scores, reveal spatial heterogeneity, and provide means to differentiate dermatomyositis patients from controls. • Diffusion imaging shows regional differences between thigh muscles of dermatomyositis patients and controls. • Signal-weighted fat fraction and diffusion metrics correlate with T1/T2 scores of disease severity. • Dermatomyositis patients show significantly higher radial diffusion exercise response than controls.

Combining anatomical, diffusion, and resting state functional magnetic resonance imaging for individual classification of mild and moderate Alzheimer's disease.

PubMed

Schouten, Tijn M; Koini, Marisa; de Vos, Frank; Seiler, Stephan; van der Grond, Jeroen; Lechner, Anita; Hafkemeijer, Anne; Möller, Christiane; Schmidt, Reinhold; de Rooij, Mark; Rombouts, Serge A R B

2016-01-01

Magnetic resonance imaging (MRI) is sensitive to structural and functional changes in the brain caused by Alzheimer's disease (AD), and can therefore be used to help in diagnosing the disease. Improving classification of AD patients based on MRI scans might help to identify AD earlier in the disease's progress, which may be key in developing treatments for AD. In this study we used an elastic net classifier based on several measures derived from the MRI scans of mild to moderate AD patients (N = 77) from the prospective registry on dementia study and controls (N = 173) from the Austrian Stroke Prevention Family Study. We based our classification on measures from anatomical MRI, diffusion weighted MRI and resting state functional MRI. Our unimodal classification performance ranged from an area under the curve (AUC) of 0.760 (full correlations between functional networks) to 0.909 (grey matter density). When combining measures from multiple modalities in a stepwise manner, the classification performance improved to an AUC of 0.952. This optimal combination consisted of grey matter density, white matter density, fractional anisotropy, mean diffusivity, and sparse partial correlations between functional networks. Classification performance for mild AD as well as moderate AD also improved when using this multimodal combination. We conclude that different MRI modalities provide complementary information for classifying AD. Moreover, combining multiple modalities can substantially improve classification performance over unimodal classification.

Spine labeling in MRI via regularized distribution matching.

PubMed

Hojjat, Seyed-Parsa; Ayed, Ismail; Garvin, Gregory J; Punithakumar, Kumaradevan

2017-11-01

This study investigates an efficient (nearly real-time) two-stage spine labeling algorithm that removes the need for an external training while being applicable to different types of MRI data and acquisition protocols. Based solely on the image being labeled (i.e., we do not use training data), the first stage aims at detecting potential vertebra candidates following the optimization of a functional containing two terms: (i) a distribution-matching term that encodes contextual information about the vertebrae via a density model learned from a very simple user input, which amounts to a point (mouse click) on a predefined vertebra; and (ii) a regularization constraint, which penalizes isolated candidates in the solution. The second stage removes false positives and identifies all vertebrae and discs by optimizing a geometric constraint, which embeds generic anatomical information on the interconnections between neighboring structures. Based on generic knowledge, our geometric constraint does not require external training. We performed quantitative evaluations of the algorithm over a data set of 90 mid-sagittal MRI images of the lumbar spine acquired from 45 different subjects. To assess the flexibility of the algorithm, we used both T1- and T2-weighted images for each subject. A total of 990 structures were automatically detected/labeled and compared to ground-truth annotations by an expert. On the T2-weighted data, we obtained an accuracy of 91.6% for the vertebrae and 89.2% for the discs. On the T1-weighted data, we obtained an accuracy of 90.7% for the vertebrae and 88.1% for the discs. Our algorithm removes the need for external training while being applicable to different types of MRI data and acquisition protocols. Based on the current testing data, a subject-specific model density and generic anatomical information, our method can achieve competitive performances when applied to T1- and T2-weighted MRI images.

CT and MRI Findings in Cerebral Aspergilloma.

PubMed

Gärtner, Friederike; Forstenpointner, Julia; Ertl-Wagner, Birgit; Hooshmand, Babak; Riedel, Christian; Jansen, Olav

2017-11-20

Purpose  Invasive aspergillosis usually affects immunocompromised patients. It carries a high risk of morbidity and mortality and usually has a nonspecific clinical presentation. Early diagnosis is essential in order to start effective treatment and improve clinical outcome. Materials and Methods  In a retrospective search of the PACS databases from two medical centers, we identified 9 patients with histologically proven cerebral aspergilloma. We systematically analyzed CT and MRI imaging findings to identify typical imaging appearances of cerebral aspergilloma. Results  CT did not show a typical appearance of the aspergillomas. In 100 % (9/9) there was a rim-attenuated diffusion restriction on MRI imaging. Multiple hypointense layers in the aspergillus wall, especially on the internal side, were detected in 100 % on T2-weighted imaging (9/9). Aspergillomas were T1-hypointense in 66 % of cases (6/9) and partly T1-hyperintense in 33 % (3/9). In 78 % (7/9) of cases, a rim-attenuated diffusion restriction was detected after contrast agent application. Conclusion  Nine cases were identified. Whereas CT features were less typical, we observed the following imaging features on MRI: A strong, rim-attenuated diffusion restriction (9/9); onion layer-like hypointense zones, in particular in the innermost part of the abscess wall on T2-weighted images (9/9). Enhancement of the lesion border was present in the majority of the cases (7/9). Key points   · There are typical MRI imaging features of aspergillomas.. · However, these findings could be affected by the immune status of the patient.. · Swift identification of aspergilloma imaging patterns is essential to allow for adequate therapeutic decision making.. Citation Format · Gärtner F, Forstenpointner J, Ertl-Wagner B et al. CT and MRI Findings in Cerebral Aspergilloma. Fortschr Röntgenstr 2017; DOI: 10.1055/s-0043-120766. © Georg Thieme Verlag KG Stuttgart · New York.

Novel use of non-echo-planar diffusion weighted MRI in monitoring disease activity and treatment response in active Grave's orbitopathy: An initial observational cohort study.

PubMed

Lingam, Ravi Kumar; Mundada, Pravin; Lee, Vickie

2018-01-10

To examine the novel use of non-echo-planar diffusion weighted MRI (DWI) in depicting activity and treatment response in active Grave's orbitopathy (GO) by assessing, with inter-observer agreement, for a correlation between its apparent diffusion coefficients (ADCs) and conventional Short tau Inversion Recovery (STIR) MRI signal-intensity ratios (SIRs). A total of 23 actively inflamed muscles and 30 muscle response episodes were analysed in patients with active GO who underwent medical treatment. The MRI orbit scans included STIR sequences and non-echo-planar DWI were evaluated. Two observers independently assessed the images qualitatively for the presence of activity in the extraocular muscles (EOMs) and recorded the STIR signal-intensity (SI), SIR (SI ratio of EOM/temporalis muscle), and ADC values of any actively inflamed muscle on the pre-treatment scans and their corresponding values on the subsequent post-treatment scans. Inter-observer agreement was examined. There was a significant positive correlation (0.57, p < 0.001) between ADC and both SIR and STIR SI of the actively inflamed EOM. There was also a significant positive correlation (0.75, p < 0.001) between SIR and ADC values depicting change in muscle activity associated with treatment response. There was good inter-observer agreement. Our preliminary results indicate that quantitative evaluation with non-echo-planar DWI ADC values correlates well with conventional STIR SIR in detecting active GO and monitoring its treatment response, with good inter-observer agreement.

Differentiation of Central Lung Cancer from Atelectasis: Comparison of Diffusion-Weighted MRI with PET/CT

PubMed Central

Yang, Rui-Meng; Li, Long; Wei, Xin-Hua; Guo, Yong-Mei; Huang, Yun-Hai; Lai, Li-Sha; Chen, A-Mei; Liu, Guo-Shun; Xiong, Wei-Feng; Luo, Liang-Ping; Jiang, Xin-Qing

2013-01-01

Objective Prospectively assess the performance of diffusion-weighted magnetic resonance imaging (DW-MRI) for differentiation of central lung cancer from atelectasis. Materials and Methods 38 consecutive lung cancer patients (26 males, 12 females; age range: 28–71 years; mean age: 49 years) who were referred for thoracic MR imaging examinations were enrolled. MR examinations were performed using a 1.5-T clinical scanner and scanning sequences of T1WI, T2WI, and DWI. Cancers and atelectasis were measured by mapping of the apparent diffusion coefficients (ADCs) obtained with a b-value of 500 s/mm2. Results PET/CT and DW-MR allowed differentiation of tumor and atelectasis in all 38 cases, but T2WI did not allow differentiation in 9 cases. Comparison of conventional T2WI and DW-MRI indicated a higher contrast noise ratio of the central lung carcinoma than the atelectasis by DW-MRI. ADC maps indicated significantly lower mean ADC in the central lung carcinoma than in the atelectasis (1.83±0.58 vs. 2.90±0.26 mm2/s, p<0.0001). ADC values of small cell lung carcinoma were significantly greater than those from squamous cell carcinoma and adenocarcinoma (p<0.0001 for both). Conclusions DW-MR imaging provides valuable information not obtained by conventional MR and may be useful for differentiation of central lung carcinoma from atelectasis. Future developments may allow DW-MR imaging to be used as an alternative to PET-CT in imaging of patients with lung cancer. PMID:23593186

Structural network efficiency is associated with cognitive impairment in small-vessel disease.

PubMed

Lawrence, Andrew J; Chung, Ai Wern; Morris, Robin G; Markus, Hugh S; Barrick, Thomas R

2014-07-22

To characterize brain network connectivity impairment in cerebral small-vessel disease (SVD) and its relationship with MRI disease markers and cognitive impairment. A cross-sectional design applied graph-based efficiency analysis to deterministic diffusion tensor tractography data from 115 patients with lacunar infarction and leukoaraiosis and 50 healthy individuals. Structural connectivity was estimated between 90 cortical and subcortical brain regions and efficiency measures of resulting graphs were analyzed. Networks were compared between SVD and control groups, and associations between efficiency measures, conventional MRI disease markers, and cognitive function were tested. Brain diffusion tensor tractography network connectivity was significantly reduced in SVD: networks were less dense, connection weights were lower, and measures of network efficiency were significantly disrupted. The degree of brain network disruption was associated with MRI measures of disease severity and cognitive function. In multiple regression models controlling for confounding variables, associations with cognition were stronger for network measures than other MRI measures including conventional diffusion tensor imaging measures. A total mediation effect was observed for the association between fractional anisotropy and mean diffusivity measures and executive function and processing speed. Brain network connectivity in SVD is disturbed, this disturbance is related to disease severity, and within a mediation framework fully or partly explains previously observed associations between MRI measures and SVD-related cognitive dysfunction. These cross-sectional results highlight the importance of network disruption in SVD and provide support for network measures as a disease marker in treatment studies. © 2014 American Academy of Neurology.

Structural network efficiency is associated with cognitive impairment in small-vessel disease

PubMed Central

Chung, Ai Wern; Morris, Robin G.; Markus, Hugh S.; Barrick, Thomas R.

2014-01-01

Objective: To characterize brain network connectivity impairment in cerebral small-vessel disease (SVD) and its relationship with MRI disease markers and cognitive impairment. Methods: A cross-sectional design applied graph-based efficiency analysis to deterministic diffusion tensor tractography data from 115 patients with lacunar infarction and leukoaraiosis and 50 healthy individuals. Structural connectivity was estimated between 90 cortical and subcortical brain regions and efficiency measures of resulting graphs were analyzed. Networks were compared between SVD and control groups, and associations between efficiency measures, conventional MRI disease markers, and cognitive function were tested. Results: Brain diffusion tensor tractography network connectivity was significantly reduced in SVD: networks were less dense, connection weights were lower, and measures of network efficiency were significantly disrupted. The degree of brain network disruption was associated with MRI measures of disease severity and cognitive function. In multiple regression models controlling for confounding variables, associations with cognition were stronger for network measures than other MRI measures including conventional diffusion tensor imaging measures. A total mediation effect was observed for the association between fractional anisotropy and mean diffusivity measures and executive function and processing speed. Conclusions: Brain network connectivity in SVD is disturbed, this disturbance is related to disease severity, and within a mediation framework fully or partly explains previously observed associations between MRI measures and SVD-related cognitive dysfunction. These cross-sectional results highlight the importance of network disruption in SVD and provide support for network measures as a disease marker in treatment studies. PMID:24951477

Magnetic single-walled carbon nanotubes as efficient drug delivery nanocarriers in breast cancer murine model: noninvasive monitoring using diffusion-weighted magnetic resonance imaging as sensitive imaging biomarker.

PubMed

Al Faraj, Achraf; Shaik, Abjal Pasha; Shaik, Asma Sultana

2015-01-01

Targeting doxorubicin (DOX) by means of single-walled carbon nanotube (SWCNT) nanocarriers may help improve the clinical utility of this highly active therapeutic agent. Active targeting of SWCNTs using tumor-specific antibody and magnetic attraction by tagging the nanotubes with iron oxide nanoparticles can potentially reduce the unnecessary side effects and provide enhanced theranostics. In the current study, the in vitro and in vivo efficacy of DOX-loaded SWCNTs as theranostic nanoprobes was evaluated in a murine breast cancer model. Iron-tagged SWCNTs conjugated with Endoglin/CD105 antibody with or without DOX were synthetized and extensively characterized. Their biocompatibility was assessed in vitro in luciferase (Luc2)-expressing 4T1 (4T1-Luc2) murine breast cancer cells using TiterTACS™ Colorimetric Apoptosis Detection Kit (apoptosis induction), poly (ADP-ribose) polymerase (marker for DNA damage), and thiobarbituric acid-reactive substances (oxidative stress generation) assays, and the efficacy of DOX-loaded SWCNTs was evaluated by measuring the radiance efficiency using bioluminescence imaging (BLI). Tumor progression and growth were monitored after 4T1-Luc2 cells inoculation using noninvasive BLI and magnetic resonance imaging (MRI) before and after subsequent injection of SWCNT complexes actively and magnetically targeted to tumor sites. Significant increases in apoptosis, DNA damage, and oxidative stress were induced by DOX-loaded SWCNTs. In addition, a tremendous decrease in bioluminescence was observed in a dose- and time-dependent manner. Noninvasive BLI and MRI revealed successful tumor growth and subsequent attenuation along with metastasis inhibition following DOX-loaded SWCNTs injection. Magnetic tagging of SWCNTs was found to produce significant discrepancies in apparent diffusion coefficient values providing a higher contrast to detect treatment-induced variations as noninvasive imaging biomarker. In addition, it allowed their sensitive noninvasive diagnosis using susceptibility-weighted MRI and their magnetic targeting using an externally applied magnet. Enhanced therapeutic efficacy of DOX delivered through antibody-conjugated magnetic SWCNTs was achieved. Further, the superiority of apparent diffusion coefficient measurements using diffusion-weighted MRI was found to be a sensitive imaging biomarker for assessment of treatment-induced changes.

Contrast-enhanced dynamic and diffusion-weighted magnetic resonance imaging at 3.0 T to assess early-stage nasopharyngeal carcinoma.

PubMed

Ni, Liangping; Liu, Ying

2018-04-01

The present study aimed to assess early-stage nasopharyngeal carcinoma (NPC) with dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and diffusion-weighted imaging (DWI) at 3.0 T. A total of 44 patients newly diagnosed with NPC were included in the present study. All patients underwent MR examination at 3.0 T using DCE-MRI and DWI. The volume transfer constant ( K trans ), flux rate constant between extravascular extracellular space and plasma ( K ep ), the volume of extravascular extracellular space per unit volume of tissue ( V e ) and the apparent diffusion coefficient (ADC) of tumours were investigated. Furthermore, the correlation between clinical stages and ADC value and K trans were analysed. The diagnostic accuracy of K trans and ADC were estimated using receiver operating characteristic curves. NPC stage correlated positively with K trans and negatively with ADC values. Additionally, tumour K trans negatively correlated with ADC value. The sensitivity and accuracy of combined K trans and ADC in distinguishing between stage II and stage III and stage III and IV were higher than the values of either measurement used separately. The present study suggested that K trans and ADC derived from DCE-MRI and DWI may be useful to detect stage early NPC accurately. K trans and ADC in combination were superior than either alone.

The physical and biological basis of quantitative parameters derived from diffusion MRI

PubMed Central

2012-01-01

Diffusion magnetic resonance imaging is a quantitative imaging technique that measures the underlying molecular diffusion of protons. Diffusion-weighted imaging (DWI) quantifies the apparent diffusion coefficient (ADC) which was first used to detect early ischemic stroke. However this does not take account of the directional dependence of diffusion seen in biological systems (anisotropy). Diffusion tensor imaging (DTI) provides a mathematical model of diffusion anisotropy and is widely used. Parameters, including fractional anisotropy (FA), mean diffusivity (MD), parallel and perpendicular diffusivity can be derived to provide sensitive, but non-specific, measures of altered tissue structure. They are typically assessed in clinical studies by voxel-based or region-of-interest based analyses. The increasing recognition of the limitations of the diffusion tensor model has led to more complex multi-compartment models such as CHARMED, AxCaliber or NODDI being developed to estimate microstructural parameters including axonal diameter, axonal density and fiber orientations. However these are not yet in routine clinical use due to lengthy acquisition times. In this review, I discuss how molecular diffusion may be measured using diffusion MRI, the biological and physical bases for the parameters derived from DWI and DTI, how these are used in clinical studies and the prospect of more complex tissue models providing helpful micro-structural information. PMID:23289085

Whole-body MR imaging, bone diffusion imaging: how and why?

PubMed

Jaramillo, Diego

2010-06-01

Whole-body MRI (W-B MRI) and diffusion-weighted imaging (DWI) are two novel techniques that greatly facilitate the evaluation of many disorders of childhood. In the musculoskeletal system, these techniques primarily aid in the evaluation of the marrow, although there is increasing interest in the study of soft-tissue abnormalities with W-B MRI and of cartilage with DWI.The normal pattern of marrow transformation affects both modalities throughout childhood. Haematopoietic marrow has a much higher signal intensity than fatty marrow on W-B MRI short tau inversion recovery (STIR) images (Darge et al. Eur J Radiol 68:289-298, 2008). Diffusion is greater in haematopoietic marrow than in fatty marrow and decreases in the skeleton with age (Jaramillo et al. Pediatr Radiol 34:S48, 2004). It is important therefore to remember that the entire skeleton is haematopoietic at birth and that there is a process of marrow transformation to fatty marrow. Marrow conversion proceeds from the fingers to the shoulders and from the toes to the hips. Within each bone, fatty marrow transformation begins in the epiphyses, and within the shaft of the long bones fatty marrow transformation begins at the diaphysis and proceeds towards the metaphyses.

The VALiDATe29 MRI Based Multi-Channel Atlas of the Squirrel Monkey Brain.

PubMed

Schilling, Kurt G; Gao, Yurui; Stepniewska, Iwona; Wu, Tung-Lin; Wang, Feng; Landman, Bennett A; Gore, John C; Chen, Li Min; Anderson, Adam W

2017-10-01

We describe the development of the first digital atlas of the normal squirrel monkey brain and present the resulting product, VALiDATe29. The VALiDATe29 atlas is based on multiple types of magnetic resonance imaging (MRI) contrast acquired on 29 squirrel monkeys, and is created using unbiased, nonlinear registration techniques, resulting in a population-averaged stereotaxic coordinate system. The atlas consists of multiple anatomical templates (proton density, T1, and T2* weighted), diffusion MRI templates (fractional anisotropy and mean diffusivity), and ex vivo templates (fractional anisotropy and a structural MRI). In addition, the templates are combined with histologically defined cortical labels, and diffusion tractography defined white matter labels. The combination of intensity templates and image segmentations make this atlas suitable for the fundamental atlas applications of spatial normalization and label propagation. Together, this atlas facilitates 3D anatomical localization and region of interest delineation, and enables comparisons of experimental data across different subjects or across different experimental conditions. This article describes the atlas creation and its contents, and demonstrates the use of the VALiDATe29 atlas in typical applications. The atlas is freely available to the scientific community.

Diffusion Kurtosis Imaging Detects Microstructural Alterations in Brain of α-Synuclein Overexpressing Transgenic Mouse Model of Parkinson's Disease: A Pilot Study.

PubMed

Khairnar, Amit; Latta, Peter; Drazanova, Eva; Ruda-Kucerova, Jana; Szabó, Nikoletta; Arab, Anas; Hutter-Paier, Birgit; Havas, Daniel; Windisch, Manfred; Sulcova, Alexandra; Starcuk, Zenon; Rektorova, Irena

2015-11-01

Evidence suggests that accumulation and aggregation of α-synuclein contribute to the pathogenesis of Parkinson's disease (PD). The aim of this study was to evaluate whether diffusion kurtosis imaging (DKI) will provide a sensitive tool for differentiating between α-synuclein-overexpressing transgenic mouse model of PD (TNWT-61) and wild-type (WT) littermates. This experiment was designed as a proof-of-concept study and forms a part of a complex protocol and ongoing translational research. Nine-month-old TNWT-61 mice and age-matched WT littermates underwent behavioral tests to monitor motor impairment and MRI scanning using 9.4 Tesla system in vivo. Tract-based spatial statistics (TBSS) and the DKI protocol were used to compare the whole brain white matter of TNWT-61 and WT mice. In addition, region of interest (ROI) analysis was performed in gray matter regions such as substantia nigra, striatum, hippocampus, sensorimotor cortex, and thalamus known to show higher accumulation of α-synuclein. For the ROI analysis, both DKI (6 b-values) protocol and conventional (2 b-values) diffusion tensor imaging (cDTI) protocol were used. TNWT-61 mice showed significant impairment of motor coordination. With the DKI protocol, mean, axial, and radial kurtosis were found to be significantly elevated, whereas mean and radial diffusivity were decreased in the TNWT-61 group compared to that in the WT controls with both TBSS and ROI analysis. With the cDTI protocol, the ROI analysis showed decrease in all diffusivity parameters in TNWT-61 mice. The current study provides evidence that DKI by providing both kurtosis and diffusivity parameters gives unique information that is complementary to cDTI for in vivo detection of pathological changes that underlie PD-like symptomatology in TNWT-61 mouse model of PD. This result is a crucial step in search for a candidate diagnostic biomarker with translational potential and relevance for human studies.

Morphological and functional evaluation of chronic pancreatitis with magnetic resonance imaging

PubMed Central

Hansen, Tine Maria; Nilsson, Matias; Gram, Mikkel; Frøkjær, Jens Brøndum

2013-01-01

Magnetic resonance imaging (MRI) techniques for assessment of morphology and function of the pancreas have been improved dramatically the recent years and MRI is very often used in diagnosing and follow-up of chronic pancreatitis (CP) patients. Standard MRI including fat-suppressed T1-weighted and T2-weighted imaging techniques reveal decreased signal and glandular atrophy of the pancreas in CP. In contrast-enhanced MRI of the pancreas in CP the pancreatic signal is usually reduced and delayed due to decreased perfusion as a result of chronic inflammation and fibrosis. Thus, morphological changes of the ductal system can be assessed by magnetic resonance cholangiopancreatography (MRCP). Furthermore, secretin-stimulated MRCP is a valuable technique to evaluate side branch pathology and the exocrine function of the pancreas and diffusion weighted imaging can be used to quantify both parenchymal fibrotic changes and the exocrine function of the pancreas. These standard and advanced MRI techniques are supplementary techniques to reveal morphological and functional changes of the pancreas in CP. Recently, spectroscopy has been used for assessment of metabolite concentrations in-vivo in different tissues and may have the potential to offer better tissue characterization of the pancreas. Hence, the purpose of the present review is to provide an update on standard and advanced MRI techniques of the pancreas in CP. PMID:24259954

Decision forests for learning prostate cancer probability maps from multiparametric MRI

NASA Astrophysics Data System (ADS)

Ehrenberg, Henry R.; Cornfeld, Daniel; Nawaf, Cayce B.; Sprenkle, Preston C.; Duncan, James S.

2016-03-01

Objectives: Advances in multiparametric magnetic resonance imaging (mpMRI) and ultrasound/MRI fusion imaging offer a powerful alternative to the typical undirected approach to diagnosing prostate cancer. However, these methods require the time and expertise needed to interpret mpMRI image scenes. In this paper, a machine learning framework for automatically detecting and localizing cancerous lesions within the prostate is developed and evaluated. Methods: Two studies were performed to gather MRI and pathology data. The 12 patients in the first study underwent an MRI session to obtain structural, diffusion-weighted, and dynamic contrast enhanced image vol- umes of the prostate, and regions suspected of being cancerous from the MRI data were manually contoured by radiologists. Whole-mount slices of the prostate were obtained for the patients in the second study, in addition to structural and diffusion-weighted MRI data, for pathology verification. A 3-D feature set for voxel-wise appear- ance description combining intensity data, textural operators, and zonal approximations was generated. Voxels in a test set were classified as normal or cancer using a decision forest-based model initialized using Gaussian discriminant analysis. A leave-one-patient-out cross-validation scheme was used to assess the predictions against the expert manual segmentations confirmed as cancer by biopsy. Results: We achieved an area under the average receiver-operator characteristic curve of 0.923 for the first study, and visual assessment of the probability maps showed 21 out of 22 tumors were identified while a high level of specificity was maintained. In addition to evaluating the model against related approaches, the effects of the individual MRI parameter types were explored, and pathological verification using whole-mount slices from the second study was performed. Conclusions: The results of this paper show that the combination of mpMRI and machine learning is a powerful tool for quantitatively diagnosing prostate cancer.

Computer-Aided Detection of Prostate Cancer with MRI: Technology and Applications

PubMed Central

Liu, Lizhi; Tian, Zhiqiang; Zhang, Zhenfeng; Fei, Baowei

2016-01-01

One in six men will develop prostate cancer in his life time. Early detection and accurate diagnosis of the disease can improve cancer survival and reduce treatment costs. Recently, imaging of prostate cancer has greatly advanced since the introduction of multi-parametric magnetic resonance imaging (mp-MRI). Mp-MRI consists of T2-weighted sequences combined with functional sequences including dynamic contrast-enhanced MRI, diffusion-weighted MRI, and MR spectroscopy imaging. Due to the big data and variations in imaging sequences, detection can be affected by multiple factors such as observer variability and visibility and complexity of the lesions. In order to improve quantitative assessment of the disease, various computer-aided detection systems have been designed to help radiologists in their clinical practice. This review paper presents an overview of literatures on computer-aided detection of prostate cancer with mp-MRI, which include the technology and its applications. The aim of the survey is threefold: an introduction for those new to the field, an overview for those working in the field, and a reference for those searching for literature on a specific application. PMID:27133005

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

DTIC Science & Technology

2013-10-01

AD_________________ Award Number: W81XWH-12-1-0597 TITLE: Parametric PET /MR Fusion Imaging to...Parametric PET /MR Fusion Imaging to Differentiate Aggressive from Indolent Primary Prostate Cancer with Application for Image-Guided Prostate Cancer Biopsies...The study investigates whether fusion PET /MRI imaging with 18F-choline PET /CT and diffusion-weighted MRI can be successfully applied to target prostate

An agent-based model identifies MRI regions of probable tumor invasion in a patient with glioblastoma

NASA Astrophysics Data System (ADS)

Chen, L. Leon; Ulmer, Stephan; Deisboeck, Thomas S.

2010-01-01

We present an application of a previously developed agent-based glioma model (Chen et al 2009 Biosystems 95 234-42) for predicting spatio-temporal tumor progression using a patient-specific MRI lattice derived from apparent diffusion coefficient (ADC) data. Agents representing collections of migrating glioma cells are initialized based upon voxels at the outer border of the tumor identified on T1-weighted (Gd+) MRI at an initial time point. These simulated migratory cells exhibit a specific biologically inspired spatial search paradigm, representing a weighting of the differential contribution from haptotactic permission and biomechanical resistance on the migration decision process. ADC data from 9 months after the initial tumor resection were used to select the best search paradigm for the simulation, which was initiated using data from 6 months after the initial operation. Using this search paradigm, 100 simulations were performed to derive a probabilistic map of tumor invasion locations. The simulation was able to successfully predict a recurrence in the dorsal/posterior aspect long before it was depicted on T1-weighted MRI, 18 months after the initial operation.

An agent-based model identifies MRI regions of probable tumor invasion in a patient with glioblastoma.

PubMed

Chen, L Leon; Ulmer, Stephan; Deisboeck, Thomas S

2010-01-21

We present an application of a previously developed agent-based glioma model (Chen et al 2009 Biosystems 95 234-42) for predicting spatio-temporal tumor progression using a patient-specific MRI lattice derived from apparent diffusion coefficient (ADC) data. Agents representing collections of migrating glioma cells are initialized based upon voxels at the outer border of the tumor identified on T1-weighted (Gd+) MRI at an initial time point. These simulated migratory cells exhibit a specific biologically inspired spatial search paradigm, representing a weighting of the differential contribution from haptotactic permission and biomechanical resistance on the migration decision process. ADC data from 9 months after the initial tumor resection were used to select the best search paradigm for the simulation, which was initiated using data from 6 months after the initial operation. Using this search paradigm, 100 simulations were performed to derive a probabilistic map of tumor invasion locations. The simulation was able to successfully predict a recurrence in the dorsal/posterior aspect long before it was depicted on T1-weighted MRI, 18 months after the initial operation.

Connective tissue of cervical carcinoma xenografts: associations with tumor hypoxia and interstitial fluid pressure and its assessment by DCE-MRI and DW-MRI.

PubMed

Hompland, Tord; Ellingsen, Christine; Galappathi, Kanthi; Rofstad, Einar K

2014-01-01

Abstract Background. A high fraction of stroma in malignant tissues is associated with tumor progression, metastasis, and poor prognosis. Possible correlations between the stromal and physiologic microenvironments of tumors and the potential of dynamic contrast-enhanced (DCE) and diffusion-weighted (DW) magnetic resonance imaging (MRI) in quantification of the stromal microenvironment were investigated in this study. Material and methods. CK-160 cervical carcinoma xenografts were used as preclinical tumor model. A total of 43 tumors were included in the study, and of these tumors, 17 were used to search for correlations between the stromal and physiologic microenvironments, 11 were subjected to DCE-MRI, and 15 were subjected to DW-MRI. DCE-MRI and DW-MRI were carried out at 1.5 T with a clinical MR scanner and a slotted tube resonator transceiver coil constructed for mice. Fraction of connective tissue (CTFCol) and fraction of hypoxic tissue (HFPim) were determined by immunohistochemistry. A Millar SPC 320 catheter was used to measure tumor interstitial fluid pressure (IFP). Results. CTFCol showed a positive correlation to IFP and an inverse correlation to HFPim. The apparent diffusion coefficient assessed by DW-MRI was inversely correlated to CTFCol, whereas no correlation was found between DCE-MRI-derived parameters and CTFCol. Conclusion. DW-MRI is a potentially useful method for characterizing the stromal microenvironment of tumors.

Carotid artery stenting with double cerebral embolic protection in asymptomatic patients - a diffusion-weighted MRI controlled study.

PubMed

Vuruskan, Ertan; Saracoglu, Erhan; Ergun, Ugur; Poyraz, Fatih; Duzen, İrfan Veysel

2017-01-01

The aim of this study was to compare the simultaneous double-protection method (proximal balloon plus distal filter) with distal-filter protection or proximal-balloon protection alone in asymptomatic patients during carotid artery stenting. 119 consecutive patients were investigated for carotid artery stentings in the extracranial internal carotid artery with the use of distal filters (n = 41, 34.4 %), proximal balloon (MoMa) protection (n = 40, 33.6 %) or double protection (n = 38, 31.9 %). Magnetic resonance imaging (MRI) was performed on all patients before the procedure, and control diffusion-weighted MRI (DW-MRI) was obtained within 24-48 h after the procedure. Procedural data, complications, success rate, major adverse cardiovascular events, and MRI findings were collected. New cerebral high-intensity (HI) lesions were observed in 47 (39.4 %) patients. HI lesions were observed in 22 (53.6 %), 15 (37.5 %), and 10 (26.3 %) of the patients with distal filters, proximal protection, and double protection, respectively (p = 0.004). The average number of HI lesions on DW-MRI was 1.80 in the distal-filter group, 0.90 in the proximal-balloon group, and 0.55 in the double-protection group (p < 0.001). Procedure and fluoroscopy times were slightly longer in the double-protection group compared to the distal- or proximal-protection groups (p = 0.001). The double (proximal plus distal) cerebral embolic protection technique is safe and effective for minimizing the risk of cerebral embolization, even in patients with asymptomatic carotid artery stenosis, despite slightly longer procedure and fluoroscopy times.
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Magnetic resonance imaging based clinical research in Alzheimer's disease.

PubMed

Fayed, Nicolás; Modrego, Pedro J; Salinas, Gulillermo Rojas; Gazulla, José

2012-01-01

Alzheimer's disease (AD) is the most common cause of dementia in elderly people in western countries. However important goals are unmet in the issue of early diagnosis and the development of new drugs for treatment. Magnetic resonance imaging (MRI) and volumetry of the medial temporal lobe structures are useful tools for diagnosis. Positron emission tomography is one of the most sensitive tests for making an early diagnosis of AD but the cost and limited availability are important caveats for its utilization. The importance of magnetic resonance techniques has increased gradually to the extent that most clinical works based on AD use these techniques as the main aid to diagnosis. However, the accuracy of structural MRI as biomarker of early AD generally reaches an accuracy of 80%, so additional biomarkers should be used to improve predictions. Other structural MRI (diffusion weighted, diffusion-tensor MRI) and functional MRI have also added interesting contribution to the understanding of the pathophysiology of AD. Magnetic resonance spectroscopy has proven useful to monitor progression and response to treatment in AD, as well as a biomarker of early AD in mild cognitive impairment.

MRI and clinical features of maple syrup urine disease: preliminary results in 10 cases.

PubMed

Cheng, Ailan; Han, Lianshu; Feng, Yun; Li, Huimin; Yao, Rong; Wang, Dengbin; Jin, Biao

2017-01-01

We aimed to evaluate the magnetic resonance imaging (MRI) and clinical features of maple syrup urine disease (MSUD). This retrospective study consisted of 10 MSUD patients confirmed by genetic testing. All patients underwent brain MRI. Phenotype, genotype, and areas of brain injury on MRI were retrospectively reviewed. Six patients (60%) had the classic form of MSUD with BCKDHB mutation, three patients (30%) had the intermittent form (two with BCKDHA mutations and one with DBT mutation), and one patient (10%) had the thiamine-responsive form with DBT mutation. On diffusion-weighted imaging, nine cases presented restricted diffusion in myelinated areas, and one intermittent case with DBT mutation was normal. The classic form of MSUD involved the basal ganglia in six cases; the cerebellum, mesencephalon, pons, and supratentorial area in five cases; and the thalamus in four cases, respectively. The intermittent form involved the cerebellum, pons, and supratentorial area in two cases. The thiamine-responsive form involved the basal ganglia and supratentorial area. Our preliminary results indicate that patients with MSUD presented more commonly in classic form with BCKDHB mutation and displayed extensive brain injury on MRI.

Neonatal physiological correlates of near-term brain development on MRI and DTI in very-low-birth-weight preterm infants.

PubMed

Rose, Jessica; Vassar, Rachel; Cahill-Rowley, Katelyn; Stecher Guzman, Ximena; Hintz, Susan R; Stevenson, David K; Barnea-Goraly, Naama

2014-01-01

Structural brain abnormalities identified at near-term age have been recognized as potential predictors of neurodevelopment in children born preterm. The aim of this study was to examine the relationship between neonatal physiological risk factors and early brain structure in very-low-birth-weight (VLBW) preterm infants using structural MRI and diffusion tensor imaging (DTI) at near-term age. Structural brain MRI, diffusion-weighted scans, and neonatal physiological risk factors were analyzed in a cross-sectional sample of 102 VLBW preterm infants (BW ≤ 1500 g, gestational age (GA) ≤ 32 weeks), who were admitted to the Lucile Packard Children's Hospital, Stanford NICU and recruited to participate prior to routine near-term brain MRI conducted at 36.6 ± 1.8 weeks postmenstrual age (PMA) from 2010 to 2011; 66/102 also underwent a diffusion-weighted scan. Brain abnormalities were assessed qualitatively on structural MRI, and white matter (WM) microstructure was analyzed quantitatively on DTI in six subcortical regions defined by DiffeoMap neonatal brain atlas. Specific regions of interest included the genu and splenium of the corpus callosum, anterior and posterior limbs of the internal capsule, the thalamus, and the globus pallidus. Regional fractional anisotropy (FA) and mean diffusivity (MD) were calculated using DTI data and examined in relation to neonatal physiological risk factors including gestational age (GA), bronchopulmonary dysplasia (BPD), necrotizing enterocolitis (NEC), retinopathy of prematurity (ROP), and sepsis, as well as serum levels of C-reactive protein (CRP), glucose, albumin, and total bilirubin. Brain abnormalities were observed on structural MRI in 38/102 infants including 35% of females and 40% of males. Infants with brain abnormalities observed on MRI had higher incidence of BPD (42% vs. 25%) and sepsis (21% vs. 6%) and higher mean and peak serum CRP levels, respectively, (0.64 vs. 0.34 mg/dL, p = .008; 1.57 vs. 0.67 mg/dL, p= .006) compared to those without. The number of signal abnormalities observed on structural MRI correlated to mean and peak CRP (rho = .316, p = .002; rho = .318, p= .002). The number of signal abnormalities observed on MRI correlated with thalamus MD (left: r= .382, p= .002; right: r= .400, p= .001), controlling for PMA-at-scan. Thalamus WM microstructure demonstrated the strongest associations with neonatal risk factors. Higher thalamus MD on the left and right, respectively, was associated with lower GA (r = -.322, p = .009; r= -.381, p= .002), lower mean albumin (r = -.276, p= .029; r= -.385, p= .002), and lower mean bilirubin (r = -.293, p= .020; r= -.337 p= .007). Results suggest that at near-term age, thalamus WM microstructure may be particularly vulnerable to certain neonatal risk factors. Interactions between albumin, bilirubin, phototherapy, and brain development warrant further investigation. Identification of physiological risk factors associated with selective vulnerability of certain brain regions at near-term age may clarify the etiology of neurodevelopmental impairment and inform neuroprotective treatment for VLBW preterm infants.

Structural Brain Atlases: Design, Rationale, and Applications in Normal and Pathological Cohorts

PubMed Central

Mandal, Pravat K.; Mahajan, Rashima; Dinov, Ivo D.

2015-01-01

Structural magnetic resonance imaging (MRI) provides anatomical information about the brain in healthy as well as in diseased conditions. On the other hand, functional MRI (fMRI) provides information on the brain activity during performance of a specific task. Analysis of fMRI data requires the registration of the data to a reference brain template in order to identify the activated brain regions. Brain templates also find application in other neuroimaging modalities, such as diffusion tensor imaging and multi-voxel spectroscopy. Further, there are certain differences (e.g., brain shape and size) in the brains of populations of different origin and during diseased conditions like in Alzheimer’s disease (AD), population and disease-specific brain templates may be considered crucial for accurate registration and subsequent analysis of fMRI as well as other neuroimaging data. This manuscript provides a comprehensive review of the history, construction and application of brain atlases. A chronological outline of the development of brain template design, starting from the Talairach and Tournoux atlas to the Chinese brain template (to date), along with their respective detailed construction protocols provides the backdrop to this manuscript. The manuscript also provides the automated workflow-based protocol for designing a population-specific brain atlas from structural MRI data using LONI Pipeline graphical workflow environment. We conclude by discussing the scope of brain templates as a research tool and their application in various neuroimaging modalities. PMID:22647262

Aiming for a shorter rheumatoid arthritis MRI protocol: can contrast-enhanced MRI replace T2 for the detection of bone marrow oedema?

PubMed

Stomp, Wouter; Krabben, Annemarie; van der Heijde, Désirée; Huizinga, Tom W J; Bloem, Johan L; van der Helm-van Mil, Annette H M; Reijnierse, Monique

2014-10-01

To determine whether T1 post-gadolinium chelate images (T1Gd) can replace T2-weighted images (T2) for evaluating bone marrow oedema (BME), thereby allowing a shorter magnetic resonance imaging (MRI) protocol in rheumatoid arthritis (RA). In 179 early arthritis patients and 43 advanced RA patients, wrist and metacarpophalangeal joints were examined on a 1.5-T extremity MRI system with a standard protocol (coronal T1, T2 fat-saturated and coronal and axial T1 fat-saturated after Gd). BME was scored according to OMERACT RAMRIS by two observers with and without T2 images available. Agreement was assessed using intraclass correlation coefficients (ICCs) for semi-quantitative scores and test characteristics with T2 images as reference. Agreement between scores based on T2 and T1Gd images was excellent ICC (0.80-0.99). At bone level, sensitivity and specificity of BME on T1Gd compared to T2 were high for both patient groups and both readers (all ≥80 %). T1Gd and T2 images are equally suitable for evaluating BME. Because contrast is usually administered to assess (teno)synovitis, a short MRI protocol of T1 and T1Gd is sufficient in RA. • Bone marrow oedema scores are equal on T2 and T1-Gd-chelate enhanced sequences. • Agreement between scores based on T2 and T1-Gd-chelate images was excellent. • Sensitivity and specificity for presence of bone marrow oedema were high. • A short protocol without T2 images suffices in rheumatoid arthritis patients.

Posterior reversible encephalopathy syndrome: a case of unusual diffusion-weighted MR images.

PubMed

Benziada-Boudour, A; Schmitt, E; Kremer, S; Foscolo, S; Rivière, A-S; Tisserand, M; Boudour, A; Bracard, S

2009-05-01

Posterior reversible encephalopathy (PRES) represents an uncommon entity related to multiple pathologies, the most common of which is hypertensive crisis. PRES is classically characterized as symmetrical parieto-occipital edema, but may affect other areas of the brain. Diffusion-weighted magnetic resonance imaging (DWI) is important for differentiating between vasogenic and cytotoxic edema. We present here the case of a 43-year-old woman, known to suffer from arterial hypertension and severe renal failure, who developed PRES with restricted apparent diffusion coefficients (ADC) in various cerebral areas, suggesting irreversible tissue damage. Nevertheless, follow-up cranial MRI revealed complete remission, indicating that restricted diffusion does not always lead to cell death in this pathology. The underlying pathophysiological mechanism is not well understood. Such reversibility of diffusion anomalies has already been reported with transient ischemia, vasospasm after subarachnoid hemorrhage and epilepsy but, to our knowledge, never before in PRES.

Diagnosis of hepatic metastasis: comparison of respiration-triggered diffusion-weighted echo-planar MRI and five t2-weighted turbo spin-echo sequences.

PubMed

Bruegel, Melanie; Gaa, Jochen; Waldt, Simone; Woertler, Klaus; Holzapfel, Konstantin; Kiefer, Berthold; Rummeny, Ernst J

2008-11-01

The purpose of this study was to compare the value of respiration-triggered diffusion-weighted (DW) single-shot echo-planar MRI (EPI) and five variants of T2-weighted turbo spin-echo (TSE) sequences in the diagnosis of hepatic metastasis. Fifty-two patients with extrahepatic primary malignant tumors underwent 1.5-T MRI that included DW EPI and the following variants of T2-weighted TSE techniques: breath-hold fat-suppressed HASTE, breath-hold fat-supressed TSE, respiration-triggered fat-suppressed TSE, breath-hold STIR, and respiration-triggered STIR. Images were reviewed independently by two blinded observers who used a 5-point confidence scale to identify lesions. Results were correlated with surgical and histopathologic findings and follow-up imaging findings. The accuracy of each technique was measured with free-response receiver operating characteristic analysis. A total of 118 hepatic metastatic lesions (mean diameter, 12.8 mm; range, 3-84 mm) were evaluated. Accuracy values were higher (p < 0.001) with DW EPI (0.91-0.92) than with the T2-weighted TSE techniques (0.47-0.67). Imaging with the HASTE sequence (0.47-0.52) was less accurate (p < 0.05) than imaging with the breath-hold TSE, breath-hold STIR, respiration-triggered TSE, and respiration-triggered STIR sequences (0.59-0.67). Sensitivity was higher (p < 0.001) with DW EPI (0.88-0.91) than with T2-weighted TSE techniques (0.45-0.62). For small (< or = 10 mm) metastatic lesions only, the differences in sensitivity between DW EPI (0.85) and T2-weighted TSE techniques (0.26-0.44) were even more pronounced. DW EPI was more sensitive and more accurate than imaging with T2-weighted TSE techniques. Because of the black-blood effect on vessels and low susceptibility to motion artifacts, DW EPI was particularly useful for the detection of small (< or = 10 mm) metastatic lesions.

Robust and fast nonlinear optimization of diffusion MRI microstructure models.

PubMed

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 run time, fit, accuracy and precision. Parameter initialization approaches were found to be relevant especially for more complex models, such as those involving several fiber orientations per voxel. For these, a fitting cascade initializing or fixing parameter values in a later optimization step from simpler models in an earlier optimization step further improved run time, fit, accuracy and precision compared to a single step fit. This establishes and makes available standards by which robust fit and accuracy can be achieved in shorter run times. This is especially relevant for the use of diffusion microstructure modeling in large group or population studies and in combining microstructure parameter maps with tractography results. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Biparametric MRI of the prostate.

PubMed

Scialpi, Michele; D'Andrea, Alfredo; Martorana, Eugenio; Malaspina, Corrado Maria; Aisa, Maria Cristina; Napoletano, Maria; Orlandi, Emanuele; Rondoni, Valeria; Scialpi, Pietro; Pacchiarini, Diamante; Palladino, Diego; Dragone, Michele; Di Renzo, Giancarlo; Simeone, Annalisa; Bianchi, Giampaolo; Brunese, Luca

2017-12-01

Biparametric Magnetic Resonance Imaging (bpMRI) of the prostate combining both morphologic T2-weighted imaging (T2WI) and diffusion-weighted imaging (DWI) is emerging as an alternative to multiparametric MRI (mpMRI) to detect, to localize and to guide prostatic targeted biopsy in patients with suspicious prostate cancer (PCa). BpMRI overcomes some limitations of mpMRI such as the costs, the time required to perform the study, the use of gadolinium-based contrast agents and the lack of a guidance for management of score 3 lesions equivocal for significant PCa. In our experience the optimal and similar clinical results of the bpMRI in comparison to mpMRI are essentially related to the DWI that we consider the dominant sequence for detection suspicious PCa both in transition and in peripheral zone. In clinical practice, the adoption of bpMRI standardized scoring system, indicating the likelihood to diagnose a clinically significant PCa and establishing the management of each suspicious category (from 1 to 4), could represent the rationale to simplify and to improve the current interpretation of mpMRI based on Prostate Imaging and Reporting Archiving Data System version 2 (PI-RADS v2). In this review article we report and describe the current knowledge about bpMRI in the detection of suspicious PCa and a simplified PI-RADS based on bpMRI for management of each suspicious PCa categories to facilitate the communication between radiologists and urologists.

Biparametric MRI of the prostate

PubMed Central

Scialpi, Michele; D’Andrea, Alfredo; Martorana, Eugenio; Malaspina, Corrado Maria; Aisa, Maria Cristina; Napoletano, Maria; Orlandi, Emanuele; Rondoni, Valeria; Scialpi, Pietro; Pacchiarini, Diamante; Palladino, Diego; Dragone, Michele; Di Renzo, Giancarlo; Simeone, Annalisa; Bianchi, Giampaolo; Brunese, Luca

2017-01-01

Biparametric Magnetic Resonance Imaging (bpMRI) of the prostate combining both morphologic T2-weighted imaging (T2WI) and diffusion-weighted imaging (DWI) is emerging as an alternative to multiparametric MRI (mpMRI) to detect, to localize and to guide prostatic targeted biopsy in patients with suspicious prostate cancer (PCa). BpMRI overcomes some limitations of mpMRI such as the costs, the time required to perform the study, the use of gadolinium-based contrast agents and the lack of a guidance for management of score 3 lesions equivocal for significant PCa. In our experience the optimal and similar clinical results of the bpMRI in comparison to mpMRI are essentially related to the DWI that we consider the dominant sequence for detection suspicious PCa both in transition and in peripheral zone. In clinical practice, the adoption of bpMRI standardized scoring system, indicating the likelihood to diagnose a clinically significant PCa and establishing the management of each suspicious category (from 1 to 4), could represent the rationale to simplify and to improve the current interpretation of mpMRI based on Prostate Imaging and Reporting Archiving Data System version 2 (PI-RADS v2). In this review article we report and describe the current knowledge about bpMRI in the detection of suspicious PCa and a simplified PI-RADS based on bpMRI for management of each suspicious PCa categories to facilitate the communication between radiologists and urologists. PMID:29201499

Correlation between tissue metabolism and cellularity assessed by standardized uptake value and apparent diffusion coefficient in peritoneal metastasis.

PubMed

Yu, Xue; Lee, Elaine Yuen Phin; Lai, Vincent; Chan, Queenie

2014-07-01

To evaluate the correlation between standardized uptake value (SUV) (tissue metabolism) and apparent diffusion coefficient (ADC) (water diffusivity) in peritoneal metastases. Patients with peritoneal dissemination detected on (18)F-fluorodeoxyglucose positron emission tomography combined with computed tomography (FDG-PET/CT) were prospectively recruited for MRI examinations with informed consent and the study was approved by the local Institutional Review Board. FDG-PET/CT, diffusion-weighted imaging (DWI), MRI, and DWI/MRI images were independently reviewed by two radiologists based on visual analysis. SUVmax/SUVmean and ADCmin/ADCmean were obtained manually by drawing ROIs over the peritoneal metastases on FDG-PET/CT and DWI, respectively. Diagnostic characteristics of each technique were evaluated. Pearson's coefficient and McNemar and Kappa tests were used for statistical analysis. Eight patients were recruited for this prospective study and 34 peritoneal metastases were evaluated. ADCmean was significantly and negatively correlated with SUVmax (r = -0.528, P = 0.001) and SUVmean (r = -0.548, P = 0.001). ADCmin had similar correlation with SUVmax (r = -0.508, P = 0.002) and SUVmean (r = -0.513, P = 0.002). DWI/MRI had high diagnostic performance (accuracy = 98%) comparable to FDG-PET/CT, in peritoneal metastasis detection. Kappa values were excellent for all techniques. There was a significant inverse correlation between SUV and ADC. © 2013 Wiley Periodicals, Inc.

Whole body MRI: Improved Lesion Detection and Characterization With Diffusion Weighted Techniques

PubMed Central

Attariwala, Rajpaul; Picker, Wayne

2013-01-01

Diffusion-weighted imaging (DWI) is an established functional imaging technique that interrogates the delicate balance of water movement at the cellular level. Technological advances enable this technique to be applied to whole-body MRI. Theory, b-value selection, common artifacts and target to background for optimized viewing will be reviewed for applications in the neck, chest, abdomen, and pelvis. Whole-body imaging with DWI allows novel applications of MRI to aid in evaluation of conditions such as multiple myeloma, lymphoma, and skeletal metastases, while the quantitative nature of this technique permits evaluation of response to therapy. Persisting signal at high b-values from restricted hypercellular tissue and viscous fluid also permits applications of DWI beyond oncologic imaging. DWI, when used in conjunction with routine imaging, can assist in detecting hemorrhagic degradation products, infection/abscess, and inflammation in colitis, while aiding with discrimination of free fluid and empyema, while limiting the need for intravenous contrast. DWI in conjunction with routine anatomic images provides a platform to improve lesion detection and characterization with findings rivaling other combined anatomic and functional imaging techniques, with the added benefit of no ionizing radiation. PMID:23960006

Single Subject Classification of Alzheimer's Disease and Behavioral Variant Frontotemporal Dementia Using Anatomical, Diffusion Tensor, and Resting-State Functional Magnetic Resonance Imaging.

PubMed

Bouts, Mark J R J; Möller, Christiane; Hafkemeijer, Anne; van Swieten, John C; Dopper, Elise; van der Flier, Wiesje M; Vrenken, Hugo; Wink, Alle Meije; Pijnenburg, Yolande A L; Scheltens, Philip; Barkhof, Frederik; Schouten, Tijn M; de Vos, Frank; Feis, Rogier A; van der Grond, Jeroen; de Rooij, Mark; Rombouts, Serge A R B

2018-01-01

Overlapping clinical symptoms often complicate differential diagnosis between patients with Alzheimer's disease (AD) and behavioral variant frontotemporal dementia (bvFTD). Magnetic resonance imaging (MRI) reveals disease specific structural and functional differences that aid in differentiating AD from bvFTD patients. However, the benefit of combining structural and functional connectivity measures to-on a subject-basis-differentiate these dementia-types is not yet known. Anatomical, diffusion tensor (DTI), and resting-state functional MRI (rs-fMRI) of 30 patients with early stage AD, 23 with bvFTD, and 35 control subjects were collected and used to calculate measures of structural and functional tissue status. All measures were used separately or selectively combined as predictors for training an elastic net regression classifier. Each classifier's ability to accurately distinguish dementia-types was quantified by calculating the area under the receiver operating characteristic curves (AUC). Highest AUC values for AD and bvFTD discrimination were obtained when mean diffusivity, full correlations between rs-fMRI-derived independent components, and fractional anisotropy (FA) were combined (0.811). Similarly, combining gray matter density (GMD), FA, and rs-fMRI correlations resulted in highest AUC of 0.922 for control and bvFTD classifications. This, however, was not observed for control and AD differentiations. Classifications with GMD (0.940) and a GMD and DTI combination (0.941) resulted in similar AUC values (p = 0.41). Combining functional and structural connectivity measures improve dementia-type differentiations and may contribute to more accurate and substantiated differential diagnosis of AD and bvFTD patients. Imaging protocols for differential diagnosis may benefit from also including DTI and rs-fMRI.

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

PubMed

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.

A comparative assessment of preclinical chemotherapeutic response of tumors using quantitative non-Gaussian diffusion MRI

PubMed Central

Xu, Junzhong; Li, Ke; Smith, R. Adam; Waterton, John C.; Zhao, Ping; Ding, Zhaohua; Does, Mark D.; Manning, H. Charles; Gore, John C.

2016-01-01

Background Diffusion-weighted MRI (DWI) signal attenuation is often not mono-exponential (i.e. non-Gaussian diffusion) with stronger diffusion weighting. Several non-Gaussian diffusion models have been developed and may provide new information or higher sensitivity compared with the conventional apparent diffusion coefficient (ADC) method. However the relative merits of these models to detect tumor therapeutic response is not fully clear. Methods Conventional ADC, and three widely-used non-Gaussian models, (bi-exponential, stretched exponential, and statistical model), were implemented and compared for assessing SW620 human colon cancer xenografts responding to barasertib, an agent known to induce apoptosis via polyploidy. Bayesian Information Criterion (BIC) was used for model selection among all three non-Gaussian models. Results All of tumor volume, histology, conventional ADC, and three non-Gaussian DWI models could show significant differences between control and treatment groups after four days of treatment. However, only the non-Gaussian models detected significant changes after two days of treatment. For any treatment or control group, over 65.7% of tumor voxels indicate the bi-exponential model is strongly or very strongly preferred. Conclusion Non-Gaussian DWI model-derived biomarkers are capable of detecting tumor earlier chemotherapeutic response of tumors compared with conventional ADC and tumor volume. The bi-exponential model provides better fitting compared with statistical and stretched exponential models for the tumor and treatment models used in the current work. PMID:27919785

Diffusion imaging quality control via entropy of principal direction distribution.

PubMed

Farzinfar, Mahshid; Oguz, Ipek; Smith, Rachel G; Verde, Audrey R; Dietrich, Cheryl; Gupta, Aditya; Escolar, Maria L; Piven, Joseph; Pujol, Sonia; Vachet, Clement; Gouttard, Sylvain; Gerig, Guido; Dager, Stephen; McKinstry, Robert C; Paterson, Sarah; Evans, Alan C; Styner, Martin A

2013-11-15

Diffusion MR imaging has received increasing attention in the neuroimaging community, as it yields new insights into the microstructural organization of white matter that are not available with conventional MRI techniques. While the technology has enormous potential, diffusion MRI suffers from a unique and complex set of image quality problems, limiting the sensitivity of studies and reducing the accuracy of findings. Furthermore, the acquisition time for diffusion MRI is longer than conventional MRI due to the need for multiple acquisitions to obtain directionally encoded Diffusion Weighted Images (DWI). This leads to increased motion artifacts, reduced signal-to-noise ratio (SNR), and increased proneness to a wide variety of artifacts, including eddy-current and motion artifacts, "venetian blind" artifacts, as well as slice-wise and gradient-wise inconsistencies. Such artifacts mandate stringent Quality Control (QC) schemes in the processing of diffusion MRI data. Most existing QC procedures are conducted in the DWI domain and/or on a voxel level, but our own experiments show that these methods often do not fully detect and eliminate certain types of artifacts, often only visible when investigating groups of DWI's or a derived diffusion model, such as the most-employed diffusion tensor imaging (DTI). Here, we propose a novel regional QC measure in the DTI domain that employs the entropy of the regional distribution of the principal directions (PD). The PD entropy quantifies the scattering and spread of the principal diffusion directions and is invariant to the patient's position in the scanner. High entropy value indicates that the PDs are distributed relatively uniformly, while low entropy value indicates the presence of clusters in the PD distribution. The novel QC measure is intended to complement the existing set of QC procedures by detecting and correcting residual artifacts. Such residual artifacts cause directional bias in the measured PD and here called dominant direction artifacts. Experiments show that our automatic method can reliably detect and potentially correct such artifacts, especially the ones caused by the vibrations of the scanner table during the scan. The results further indicate the usefulness of this method for general quality assessment in DTI studies. Copyright © 2013 Elsevier Inc. All rights reserved.

Diffusion imaging quality control via entropy of principal direction distribution

PubMed Central

Oguz, Ipek; Smith, Rachel G.; Verde, Audrey R.; Dietrich, Cheryl; Gupta, Aditya; Escolar, Maria L.; Piven, Joseph; Pujol, Sonia; Vachet, Clement; Gouttard, Sylvain; Gerig, Guido; Dager, Stephen; McKinstry, Robert C.; Paterson, Sarah; Evans, Alan C.; Styner, Martin A.

2013-01-01

Diffusion MR imaging has received increasing attention in the neuroimaging community, as it yields new insights into the microstructural organization of white matter that are not available with conventional MRI techniques. While the technology has enormous potential, diffusion MRI suffers from a unique and complex set of image quality problems, limiting the sensitivity of studies and reducing the accuracy of findings. Furthermore, the acquisition time for diffusion MRI is longer than conventional MRI due to the need for multiple acquisitions to obtain directionally encoded Diffusion Weighted Images (DWI). This leads to increased motion artifacts, reduced signal-to-noise ratio (SNR), and increased proneness to a wide variety of artifacts, including eddy-current and motion artifacts, “venetian blind” artifacts, as well as slice-wise and gradient-wise inconsistencies. Such artifacts mandate stringent Quality Control (QC) schemes in the processing of diffusion MRI data. Most existing QC procedures are conducted in the DWI domain and/or on a voxel level, but our own experiments show that these methods often do not fully detect and eliminate certain types of artifacts, often only visible when investigating groups of DWI's or a derived diffusion model, such as the most-employed diffusion tensor imaging (DTI). Here, we propose a novel regional QC measure in the DTI domain that employs the entropy of the regional distribution of the principal directions (PD). The PD entropy quantifies the scattering and spread of the principal diffusion directions and is invariant to the patient's position in the scanner. High entropy value indicates that the PDs are distributed relatively uniformly, while low entropy value indicates the presence of clusters in the PD distribution. The novel QC measure is intended to complement the existing set of QC procedures by detecting and correcting residual artifacts. Such residual artifacts cause directional bias in the measured PD and here called dominant direction artifacts. Experiments show that our automatic method can reliably detect and potentially correct such artifacts, especially the ones caused by the vibrations of the scanner table during the scan. The results further indicate the usefulness of this method for general quality assessment in DTI studies. PMID:23684874

Diffusion-weighted imaging is helpful in the accurate non-invasive diagnosis of breast abscess: correlation with necrotic breast cancer.

PubMed

Wang, Cuiyan; Eghtedari, Mohammad; Yang, Wei Tse; Dogan, Basak Erguvan

2018-03-22

Clinical differentiation of atypical breast abscesses from necrotic tumour in premenopausal women is challenging and may delay appropriate therapy. In this case report, we present a 36-year-old woman with signs, symptoms and conventional imaging features of malignancy who underwent breast MRI. On diffusion-weighted imaging (DWI), profoundly low apparent diffusion coefficient values were a distinguishing sign of breast abscess from necrotic breast cancer, and helped manage the patient conservatively. We present a companion case of necrotic breast tumour highlighting significant differences in DWI. © BMJ Publishing Group Ltd (unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Inter- and intraobserver agreement of ADC measurements of lung cancer in free breathing, breath-hold and respiratory triggered diffusion-weighted MRI.

PubMed

Cui, Lei; Yin, Jian-Bing; Hu, Chun-Hong; Gong, Shen-Chu; Xu, Jun-Feng; Yang, Ju-Shun

2016-01-01

To prospectively evaluate the inter- and intraobserver agreement of apparent diffusion coefficient (ADC) measurements in free breathing, breath-hold, and respiratory triggered diffusion-weighted imaging (DWI) of lung cancer. Twenty-two patients with lung cancer (tumor size >2cm) underwent DWIs (3.0T) in three imaging methods. Lesion ADCs were measured twice by both of the two independent observers and compared. No statistical significance was found among methods, though respiratory-triggered DWI tended to have higher ADCs than breath-hold DWI. Great inter- and intraobserver agreement was shown. ADCs had good inter- and intraobserver agreement in all three DWI methods. Copyright © 2016 Elsevier Inc. All rights reserved.

Preterm birth leads to hyper-reactive cognitive control processing and poor white matter organization in adulthood.

PubMed

Olsen, Alexander; Dennis, Emily L; Evensen, Kari Anne I; Husby Hollund, Ingrid Marie; Løhaugen, Gro C C; Thompson, Paul M; Brubakk, Ann-Mari; Eikenes, Live; Håberg, Asta K

2018-02-15

Individuals born preterm with very low birth weight (VLBW; birth weight ≤ 1500 g) are at high risk for perinatal brain injuries and deviant brain development, leading to increased chances of later cognitive, emotional, and behavioral problems. Here we investigated the neuronal underpinnings of both reactive and proactive cognitive control processes in adults with VLBW. We included 32 adults born preterm with VLBW (before 37th week of gestation) and 32 term-born controls (birth weight ≥10th percentile for gestational age) between 22 and 24 years of age that have been followed prospectively since birth. Participants performed a well-validated Not-X continuous performance test (CPT) adapted for use in a mixed block- and event-related fMRI protocol. BOLD fMRI and DTI data was acquired on a 3T scanner. Performance on the Not-X CPT was highly similar between groups. However, the VLBW group demonstrated hyper-reactive cognitive control processing and disrupted white matter organization. The hyper-reactive brain activation signature in VLBW adults was associated with lower gestational age, lower fluid intelligence score, and anxiety problems. Automated Multi-Atlas Tract Extraction (AutoMATE) analyses revealed that this disruption of normal brain function was accompanied by poorer white matter organization in the anterior thalamic radiation and the cingulum, as reflected in both reduced fractional anisotropy and increased mean diffusivity. These findings show that the preterm behavioral phenotype is associated with predominantly reactive-, rather than proactive cognitive control processing, as well as white matter abnormalities, that may underlie common difficulties that many preterm born individuals experience in everyday life. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Quantitative characterization of the imaging limits of diffuse low-grade oligodendrogliomas.

PubMed

Gerin, Chloé; Pallud, Johan; Deroulers, Christophe; Varlet, Pascale; Oppenheim, Catherine; Roux, Francois-Xavier; Chrétien, Fabrice; Thomas, Stephen R; Grammaticos, Basile; Badoual, Mathilde

2013-10-01

Supratentorial diffuse low-grade gliomas in adults extend beyond maximal visible MRI-defined abnormalities, and a gap exists between the imaging signal changes and the actual tumor margins. Direct quantitative comparisons between imaging and histological analyses are lacking to date. However, they are of the utmost importance if one wishes to develop realistic models for diffuse glioma growth. In this study, we quantitatively compared the cell concentration and the edema fraction from human histological biopsy samples (BSs) performed inside and outside imaging abnormalities during serial imaging-based stereotactic biopsy of diffuse low-grade gliomas. The cell concentration was significantly higher in BSs located inside (1189 ± 378 cell/mm(2)) than outside (740 ± 124 cell/mm(2)) MRI-defined abnormalities (P = .0003). The edema fraction was significantly higher in BSs located inside (mean, 45% ± 23%) than outside (mean, 5 %± 9%) MRI-defined abnormalities (P < .0001). At borders of the MRI-defined abnormalities, 20% of the tissue surface area was occupied by edema and only 3% by tumor cells. The cycling cell concentration was significantly higher in BSs located inside (10 ± 12 cell/mm(2)), compared with outside (0.5 ± 0.9 cell/mm(2)), MRI-defined abnormalities (P = .0001). We showed that the margins of T2-weighted signal changes are mainly correlated with the edema fraction. In 62.5% of patients, the cycling tumor cell fraction (defined as the ratio of the cycling tumor cell concentration to the total number of tumor cells) was higher at the limits of the MRI-defined abnormalities than closer to the center of the tumor. In the remaining patients, the cycling tumor cell fraction increased towards the center of the tumor.

Cervical Gross Tumor Volume Dose Predicts Local Control Using Magnetic Resonance Imaging/Diffusion-Weighted Imaging—Guided High-Dose-Rate and Positron Emission Tomography/Computed Tomography—Guided Intensity Modulated Radiation Therapy

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

Dyk, Pawel; Jiang, Naomi; Sun, Baozhou

2014-11-15

Purpose: Magnetic resonance imaging/diffusion weighted-imaging (MRI/DWI)-guided high-dose-rate (HDR) brachytherapy and {sup 18}F-fluorodeoxyglucose (FDG) — positron emission tomography/computed tomography (PET/CT)-guided intensity modulated radiation therapy (IMRT) for the definitive treatment of cervical cancer is a novel treatment technique. The purpose of this study was to report our analysis of dose-volume parameters predicting gross tumor volume (GTV) control. Methods and Materials: We analyzed the records of 134 patients with International Federation of Gynecology and Obstetrics stages IB1-IVB cervical cancer treated with combined MRI-guided HDR and IMRT from July 2009 to July 2011. IMRT was targeted to the metabolic tumor volume and lymph nodesmore » by use of FDG-PET/CT simulation. The GTV for each HDR fraction was delineated by use of T2-weighted or apparent diffusion coefficient maps from diffusion-weighted sequences. The D100, D90, and Dmean delivered to the GTV from HDR and IMRT were summed to EQD2. Results: One hundred twenty-five patients received all irradiation treatment as planned, and 9 did not complete treatment. All 134 patients are included in this analysis. Treatment failure in the cervix occurred in 24 patients (18.0%). Patients with cervix failures had a lower D100, D90, and Dmean than those who did not experience failure in the cervix. The respective doses to the GTV were 41, 58, and 136 Gy for failures compared with 67, 99, and 236 Gy for those who did not experience failure (P<.001). Probit analysis estimated the minimum D100, D90, and Dmean doses required for ≥90% local control to be 69, 98, and 260 Gy (P<.001). Conclusions: Total dose delivered to the GTV from combined MRI-guided HDR and PET/CT-guided IMRT is highly correlated with local tumor control. The findings can be directly applied in the clinic for dose adaptation to maximize local control.« less

[Reversible neurotoxicity secondary to metronidazole: report of one case].

PubMed

Retamal-Riquelme, Eva; Soto-San Martín, Hernán; Vallejos-Castro, José; Galdames-Poblete, Daniel

2014-03-01

Metronidazole can cause adverse effects both in the central and peripheral nervous system. We report a 34-year-old female who presented a reversible cerebellar syndrome and peripheral neuropathy as an adverse effect associated with the use of metronidazole. Brain magnetic resonance imaging (MRI) showed hyperintense T2 and FLAIR bilateral symmetrical cerebellar lesions, without contrast enhancement or mass effect, isointense in diffusion-weighted imaging and hypointense in apparent diffusion coefficient sequences. Also, electrophysiological evaluation was consistent with axonal polyneuropathy. She had received metronidazole for a liver abscess during 49 days. After discontinuation of metronidazole, she had rapid regression of cerebellar symptoms and normalization of MRI, with subsequent disappearance of peripheral symptoms. The brain MRI, electromyography and nerve conduction studies performed at 35 months later showed complete resolution of the lesions. Although metronidazole neurotoxicity is a rare event, it must be borne in mind because the prognosis is usually favorable after stopping the drug.

The Spatial Relationship between Apparent Diffusion Coefficient and Standardized Uptake Value of 18F-Fluorodeoxyglucose Has a Crucial Influence on the Numeric Correlation of Both Parameters in PET/MRI of Lung Tumors

PubMed Central

Stieltjes, Bram; Weikert, Thomas; Gatidis, Sergios; Wiese, Mark; Wild, Damian; Lardinois, Didier

2017-01-01

The minimum apparent diffusion coefficient (ADCmin) derived from diffusion-weighted MRI (DW-MRI) and the maximum standardized uptake value (SUVmax) of FDG-PET are markers of aggressiveness in lung cancer. The numeric correlation of the two parameters has been extensively studied, but their spatial interplay is not well understood. After FDG-PET and DW-MRI coregistration, values and location of ADCmin- and SUVmax-voxels were analyzed. The upper limit of the 95% confidence interval for registration accuracy of sequential PET/MRI was 12 mm, and the mean distance (D) between ADCmin- and SUVmax-voxels was 14.0 mm (average of two readers). Spatial mismatch (D > 12 mm) between ADCmin and SUVmax was found in 9/25 patients. A considerable number of mismatch cases (65%) was also seen in a control group that underwent simultaneous PET/MRI. In the entire patient cohort, no statistically significant correlation between SUVmax and ADCmin was seen, while a moderate negative linear relationship (r = −0.5) between SUVmax and ADCmin was observed in tumors with a spatial match (D ≤ 12 mm). In conclusion, spatial mismatch between ADCmin and SUVmax is found in a considerable percentage of patients. The spatial connection of the two parameters SUVmax and ADCmin has a crucial influence on their numeric correlation. PMID:29391862

The Spatial Relationship between Apparent Diffusion Coefficient and Standardized Uptake Value of 18F-Fluorodeoxyglucose Has a Crucial Influence on the Numeric Correlation of Both Parameters in PET/MRI of Lung Tumors.

PubMed

Sauter, Alexander W; Stieltjes, Bram; Weikert, Thomas; Gatidis, Sergios; Wiese, Mark; Klarhöfer, Markus; Wild, Damian; Lardinois, Didier; Bremerich, Jens; Sommer, Gregor

2017-01-01

The minimum apparent diffusion coefficient (ADC min ) derived from diffusion-weighted MRI (DW-MRI) and the maximum standardized uptake value (SUV max ) of FDG-PET are markers of aggressiveness in lung cancer. The numeric correlation of the two parameters has been extensively studied, but their spatial interplay is not well understood. After FDG-PET and DW-MRI coregistration, values and location of ADC min - and SUV max -voxels were analyzed. The upper limit of the 95% confidence interval for registration accuracy of sequential PET/MRI was 12 mm, and the mean distance ( D ) between ADC min - and SUV max -voxels was 14.0 mm (average of two readers). Spatial mismatch ( D > 12 mm) between ADC min and SUV max was found in 9/25 patients. A considerable number of mismatch cases (65%) was also seen in a control group that underwent simultaneous PET/MRI. In the entire patient cohort, no statistically significant correlation between SUV max and ADC min was seen, while a moderate negative linear relationship ( r = -0.5) between SUV max and ADC min was observed in tumors with a spatial match ( D ≤ 12 mm). In conclusion, spatial mismatch between ADC min and SUV max is found in a considerable percentage of patients. The spatial connection of the two parameters SUV max and ADC min has a crucial influence on their numeric correlation.

Cerebral edema induced in mice by a convulsive dose of soman. Evaluation through diffusion-weighted magnetic resonance imaging and histology

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

Testylier, Guy; Lahrech, Hana; Universite Joseph Fourier, Grenoble, F-38043

2007-04-15

Purpose: In the present study, diffusion-weighted magnetic resonance imaging (DW-MRI) and histology were used to assess cerebral edema and lesions in mice intoxicated by a convulsive dose of soman, an organophosphate compound acting as an irreversible cholinesterase inhibitor. Methods: Three hours and 24 h after the intoxication with soman (172 {mu}g/kg), the mice were anesthetized with an isoflurane/N{sub 2}O mixture and their brain examined with DW-MRI. After the imaging sessions, the mice were sacrificed for histological analysis of their brain. Results: A decrease in the apparent diffusion coefficient (ADC) was detected as soon as 3 h after the intoxication andmore » was found strongly enhanced at 24 h. A correlation was obtained between the ADC change and the severity of the overall brain damage (edema and cellular degeneration): the more severe the damage, the stronger the ADC drop. Anesthesia was shown to interrupt soman-induced seizures and to attenuate edema and cell change in certain sensitive brain areas. Finally, brain water content was assessed using the traditional dry/wet weight method. A significant increase of brain water was observed following the intoxication. Conclusions: The ADC decrease observed in the present study suggests that brain edema in soman poisoning is mainly intracellular and cytotoxic. Since entry of water into Brain was also evidenced, this type of edema is certainly mixed with others (vasogenic, hydrostatic, osmotic). The present study confirms the potential of DW-MRI as a non-invasive tool for monitoring the acute neuropathological consequences (edema and neurodegeneration) of soman-induced seizures.« less

Technical Note: A safe, cheap, and easy-to-use isotropic diffusion MRI phantom for clinical and multicenter studies.

PubMed

Pullens, Pim; Bladt, Piet; Sijbers, Jan; Maas, Andrew I R; Parizel, Paul M

2017-03-01

Since Diffusion Weighted Imaging (DWI) data acquisition and processing are not standardized, substantial differences in DWI derived measures such as Apparent Diffusion Coefficient (ADC) may arise which are related to the acquisition or MRI processing method, but not to the sample under study. Quality assurance using a standardized test object, or phantom, is a key factor in standardizing DWI across scanners. Current diffusion phantoms are either complex to use, not available in larger quantities, contain substances unwanted in a clinical environment, or are expensive. A diffusion phantom based on a polyvinylpyrrolidone (PVP) solution, together with a phantom holder, is presented and compared to existing diffusion phantoms for use in clinical DWI scans. An ADC vs. temperature calibration curve was obtained. ADC of the phantom (808 to 857 ± 0.2 mm 2 /s) is in the same range as ADC values found in brain tissue. ADC measurements are highly reproducible across time with an intra-class correlation coefficient of > 0.8. ADC as function of temperature (in Kelvin) can be estimated as ADCm(T)=[exp(-7.09)·exp-2903.81T-1293.55] with a total uncertainty (95% confidence limit) of ± 1.7%. We present an isotropic diffusion MRI phantom, together with its temperature calibration curve, that is easy-to-use in a clinical environment, cost-effective, reproducible to produce, and that contains no harmful substances. © 2017 American Association of Physicists in Medicine.

Characterization of diffuse orbital mass using Apparent diffusion coefficient in 3-tesla MRI.

PubMed

ElKhamary, Sahar M; Galindo-Ferreiro, Alicia; AlGhafri, Laila; Khandekar, Rajiv; Schellini, Silvana Artioli

2018-01-01

To evaluate if the apparent diffusion coefficient (ADC) value in diffusion-weighted magnetic resonance imaging (DW-MRI) improves the diagnostic accuracy of diffuse orbital masses. ADC DW-MRI was used to evaluate cases of diffuse orbital masses at our institution from 2000 to 2015. Lesions were grouped according to histopathologic diagnosis as, benign, pre-malignant and malignant. Lymphoproliferative lesions were further subgrouped as lymphoma or other lymphoproliferative lesions. The validity of the ADC value for the diffuse orbital mass was compared between groups. The area under curve (AUC) was also calculated. Thirty-nine cases of diffuse orbital masses were evaluated. The median ADC was 0.58 (25% quartile 0.48; minimum: 0.45; maximum: 1.72 × 10 (-3) ) for the malignant tumors and 1.19 (25% quartile 0.7; minimum: 0.5; maximum: 1.95 × 10 (-3)  mm (2)  s (-1) ) for benign lesions. This difference in ADC between lesions was statistically significant (Mann Whitney U test P < 0.001). The median ADC was 0.51 (25% quartile 0.48) for lymphomas and 0.9 (25% quartile 0.7) for other lymphoproliferative lesions. This difference in ADC was statistically significant (Mann Whitney U test P = 0.02). An ADC value of 0.8 × 10 (-3)  mm (2)  s (-1) was noted as the ideal threshold value for differentiating malignant from benign diffuse orbital masses. The validity of ADC in predicting a malignant or benign diffuse orbital mass had a sensitivity of 87%, specificity of 67% and accuracy of 88%. ADC is a promising imaging metric to characterize malignant and benign diffuse orbital masses and to distinguish lymphomas from other non-lymphoproliferative lesions.

Early detection of response to radiation therapy in patients with brain malignancies using conventional and high b-value diffusion-weighted magnetic resonance imaging.

PubMed

Mardor, Yael; Pfeffer, Raphael; Spiegelmann, Roberto; Roth, Yiftach; Maier, Stephan E; Nissim, Ouzi; Berger, Raanan; Glicksman, Ami; Baram, Jacob; Orenstein, Arie; Cohen, Jack S; Tichler, Thomas

2003-03-15

To study the feasibility of using diffusion-weighted magnetic resonance imaging (DWMRI), which is sensitive to the diffusion of water molecules in tissues, for detection of early tumor response to radiation therapy; and to evaluate the additional information obtained from high DWMRI, which is more sensitive to low-mobility water molecules (such as intracellular or bound water), in increasing the sensitivity to response. Standard MRI and DWMRI were acquired before and at regular intervals after initiating radiation therapy for 10 malignant brain lesions in eight patients. One week posttherapy, three of six responding lesions showed an increase in the conventional DWMRI parameters. Another three responding lesions showed no change. Four nonresponding lesions showed a decrease or no change. The early change in the diffusion parameters was enhanced by using high DWMRI. When high DWMRI was used, all responding lesions showed increase in the diffusion parameter and all nonresponding lesions showed no change or decrease. Response was determined by standard MRI 7 weeks posttherapy. The changes in the diffusion parameters measured 1 week after initiating treatment were correlated with later tumor response or no response (P <.006). This correlation was increased to P <.0006 when high DWMRI was used. The significant correlation between changes in diffusion parameters 1 week after initiating treatment and later tumor response or no response suggests the feasibility of using DWMRI for early, noninvasive prediction of tumor response. The ability to predict response may enable early termination of treatment in nonresponding patients, prevent additional toxicity, and allow for early changes in treatment.

Individual white matter fractional anisotropy analysis on patients with MRI negative partial epilepsy.

PubMed

Duning, Thomas; Kellinghaus, Christoph; Mohammadi, Siawoosh; Schiffbauer, Hagen; Keller, Simon; Ringelstein, E Bernd; Knecht, Stefan; Deppe, Michael

2010-02-01

Conventional structural MRI fails to identify a cerebral lesion in 25% of patients with cryptogenic partial epilepsy (CPE). Diffusion tensor imaging is an MRI technique sensitive to microstructural abnormalities of cerebral white matter (WM) by quantification of fractional anisotropy (FA). The objectives of the present study were to identify focal FA abnormalities in patients with CPE who were deemed MRI negative during routine presurgical evaluation. Diffusion tensor imaging at 3 T was performed in 12 patients with CPE and normal conventional MRI and in 67 age matched healthy volunteers. WM integrity was compared between groups on the basis of automated voxel-wise statistics of FA maps using an analysis of covariance. Volumetric measurements from high resolution T1-weighted images were also performed. Significant FA reductions in WM regions encompassing diffuse areas of the brain were observed when all patients as a group were compared with controls. On an individual basis, voxel based analyses revealed widespread symmetrical FA reduction in CPE patients. Furthermore, asymmetrical temporal lobe FA reduction was consistently ipsilateral to the electroclinical focus. No significant correlations were found between FA alterations and clinical data. There were no differences in brain volumes of CPE patients compared with controls. Despite normal conventional MRI, WM integrity abnormalities in CPE patients extend far beyond the epileptogenic zone. Given that unilateral temporal lobe FA abnormalities were consistently observed ipsilateral to the seizure focus, analysis of temporal FA may provide an informative in vivo investigation into the localisation of the epileptogenic zone in MRI negative patients.

Unusual MRI findings in an immunocompetent patient with EBV encephalitis: a case report

PubMed Central

2011-01-01

Blackground It is well-known that Epstein-Barr virus (EBV) can affect the central nervous system (CNS). Case presentation Herein the authors report unusual timely Magnetic Resonance Imaging (MRI) brain scan findings in an immunocompetent patient with EBV encephalitis. Diffusion weighted MRI sequence performed during the acute phase of the disease was normal, whereas the Fast Relaxation Fast Spin Echo T2 image showed diffuse signal intensity changes in white matter. The enhancement pattern suggested an inflammatory response restricted to the brain microcirculation. Acyclovir and corticosteroid therapy was administered. After three weeks, all signal intensities returned to normal and the patient showed clinical recovery. Conclusion This report demonstrates that EBV in an immunocompetent adult can present with diffuse, reversible brain white matter involvement in the acute phase of mononucleosis. Moreover, our case suggests that a negative DWI sequence is associated with a favorable improvement in severe EBV CNS infection. More extensive studies are needed to assess what other instrumental data can help to distinguish viral lesions from other causes in the acute phase of disease. PMID:21435249

In vivo MRI assessment of permanent middle cerebral artery occlusion by electrocoagulation: pitfalls of procedure

PubMed Central

2010-01-01

Permanent middle cerebral artery (MCA) occlusion (pMCAO) by electrocoagulation is a commonly used model but with potential traumatic lesions. Early MRI monitoring may assess pMCAO for non-specific brain damage. The surgical steps of pMCAO were evaluated for traumatic cerebral injury in 22 Swiss mice using diffusion and T2-weighted MRI (7T) performed within 1 h and 24 h after surgery. Temporal muscle cauterization without MCA occlusion produced an early T2 hyperintensity mimicking an infarct. No lesion was visible after temporal muscle incision or craniotomy. Early MRI monitoring is useful to identify non-specific brain injury that could hamper neuroprotective drugs assessment. PMID:20298536

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

NASA Astrophysics Data System (ADS)

Mahmood, Faisal; Johannesen, Helle H.; Geertsen, Poul; Hansen, Rasmus H.

2017-04-01

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 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 for acquiring the DW-MRI scan during the course of treatment, since to our knowledge this important question has not been addressed directly in previous studies. Twenty-nine metastases (N  =  29) from twenty-one patients, treated with whole-brain fractionated external beam RT were analyzed. Patients were scanned with a 1 T MRI system to acquire DW-, T2*W-, T2W- and T1W scans, before start of RT, at each fraction and at follow up two to three months after RT. The DW-MRI parameters were derived using regions of interest based on high b-value images (b  =  800 s mm-2). Both volumetric and RECIST criteria were applied for response evaluation. It was found that in non-responding metastases the mean ADC decreased and in responding metastases it increased. The volume based response proved to be far more consistently predictable by the ADC change found at fraction number 7 and later, compared to the linear response (RECIST). The perfusion fraction and pseudo diffusion coefficient did not show sufficient prognostic value with either response assessment criteria. In conclusion this study shows that the ADC derived using high b-values may be a reliable biomarker for early assessment of radiotherapy response for brain metastases patients. The earliest response stratification can be achieved using two DW-MRI scans, one pre-treatment and one at treatment day 7-9 (equivalent to 21 Gy).

A reliability assessment of constrained spherical deconvolution-based diffusion-weighted magnetic resonance imaging in individuals with chronic stroke.

PubMed

Snow, Nicholas J; Peters, Sue; Borich, Michael R; Shirzad, Navid; Auriat, Angela M; Hayward, Kathryn S; Boyd, Lara A

2016-01-15

Diffusion-weighted magnetic resonance imaging (DW-MRI) is commonly used to assess white matter properties after stroke. Novel work is utilizing constrained spherical deconvolution (CSD) to estimate complex intra-voxel fiber architecture unaccounted for with tensor-based fiber tractography. However, the reliability of CSD-based tractography has not been established in people with chronic stroke. Establishing the reliability of CSD-based DW-MRI in chronic stroke. High-resolution DW-MRI was performed in ten adults with chronic stroke during two separate sessions. Deterministic region of interest-based fiber tractography using CSD was performed by two raters. Mean fractional anisotropy (FA), apparent diffusion coefficient (ADC), tract number, and tract volume were extracted from reconstructed fiber pathways in the corticospinal tract (CST) and superior longitudinal fasciculus (SLF). Callosal fiber pathways connecting the primary motor cortices were also evaluated. Inter-rater and test-retest reliability were determined by intra-class correlation coefficients (ICCs). ICCs revealed excellent reliability for FA and ADC in ipsilesional (0.86-1.00; p<0.05) and contralesional hemispheres (0.94-1.00; p<0.0001), for CST and SLF fibers; and excellent reliability for all metrics in callosal fibers (0.85-1.00; p<0.05). ICC ranged from poor to excellent for tract number and tract volume in ipsilesional (-0.11 to 0.92; p≤0.57) and contralesional hemispheres (-0.27 to 0.93; p≤0.64), for CST and SLF fibers. Like other select DW-MRI approaches, CSD-based tractography is a reliable approach to evaluate FA and ADC in major white matter pathways, in chronic stroke. Future work should address the reproducibility and utility of CSD-based metrics of tract number and tract volume. Copyright © 2015 Elsevier B.V. All rights reserved.

Differentiation of benign and malignant lesions of the tongue by using diffusion-weighted MRI at 3.0 T.

PubMed

Li, S; Cheng, J; Zhang, Y; Zhang, Z

2015-01-01

Diffusion-weighted MRI (DWI) has been introduced in head and neck lesions and adds important information to the findings obtained through conventional MRI. The purpose of this study was to assess the role of DWI in differentiating benign and malignant lesions of the tongue at 3.0-T field strength imaging. 78 patients with 78 lingual lesions underwent conventional MRI and DWI with b-values of 0 and 1000 s mm(-2) before therapy. The apparent diffusion coefficient (ADC) maps were reconstructed, and the ADC values of the lingual lesions were calculated and compared between benign and malignant lesions of the tongue. The mean ADC values of the malignant tumours, benign solid lesions and cystic lesions were (1.08±0.16)×10(-3), (1.68±0.33)×10(-3) and (2.21±0.35)×10(-3) mm2 s(-1), respectively. The mean ADC values of malignant tumours were significantly lower (p<0.001) than those of benign solid lesions, and the mean ADC values of benign solid lesions were significantly lower (p<0.001) than those of cystic lesions. Receiver operating characteristic analysis showed that when an ADC value<.31×10(-3) mm2 s(-1) was used for predicting malignancy, the highest accuracy of 95.3%, sensitivity of 92.6% and specificity of 97.3% were obtained. ADC values of benign and malignant lesions are significantly different at 3.0-T imaging. DWI can be applied as a complementary tool in the differentiation of benign and malignant lesions of the tongue.

Quantitative Analysis of Diffusion-Weighted Imaging for Diagnosis of Puerperal Breast Abscess After Polyacrylamide Hydrogel Augmentation Mammoplasty: Compared with Other Conventional Modalities.

PubMed

Liu, Lihua; Long, Miaomiao; Wang, Junping; Liu, Ning; Ge, Xihong; Hu, Zhandong; Shen, Wen

2015-02-01

Puerperal breast abscess after polyacrylamide hydrogel (PAAG) augmentation mammoplasty can induce breast auto-inflation resulting in serious consequences. Mammography, ultrasound, and conventional MRI are poor at detecting related PAAG abnormality histologically. We evaluated the value of diffusion-weighted imaging (DWI) in the quantitative analysis of puerperal PAAG abscess after augmentation mammoplasty. This was a retrospective study, and a waiver for informed consent was granted. Sixteen puerperal women with breast discomfort underwent conventional breast non-enhanced MRI and axial DWI using a 3T MR scanner. Qualitative analysis of the signal intensity on DWI and conventional sequences was performed. The apparent diffusion coefficient (ADC) values of the affected and contralateral normal PAAG cysts were measured quantitatively. Paired t test was used to evaluate whether there was significant difference. Both affected and normal PAAG cysts showed equal signal intensity on conventional T1WI and fat saturation T2WI, which were not helpful in detecting puerperal PAAG abscess. However, the affected PAAG cysts had a significantly decreased ADC value of 1.477 ± 0.332 × 10(-3)mm(2)/s and showed obvious hypo-intensity on the ADC map and increased signal intensity on DWI compared with the ADC value of 2.775 ± 0.233 × 10(-3)mm(2)/s of the contralateral normal PAAG cysts. DWI and quantitative measurement of ADC values are of great value for the diagnosis of puerperal PAAG abscess. Standardized MRI should be suggested to these puerperal women with breast discomfort or just for the purpose of check up. DWI should be selected as the essential MRI sequence.

Regional Microstructural and Volumetric Magnetic Resonance Imaging (MRI) Abnormalities in the Corpus Callosum of Neonates With Congenital Heart Defect Undergoing Cardiac Surgery.

PubMed

Hagmann, Cornelia; Singer, Jitka; Latal, Beatrice; Knirsch, Walter; Makki, Malek

2016-03-01

The purpose of the study is to investigate the structural development of the corpus callosum in term neonates with congenital heart defect before and after surgery using diffusion tensor imaging and 3-dimensional T1-weighted magnetic resonance imaging (MRI). We compared parallel and radial diffusions, apparent diffusion coefficient (ADC), fractional anisotropy, and volume of 5 substructures of the corpus callosum: genu, rostral body, body, isthmus, and splenium. Compared to healthy controls, we found a significantly lower volume of the splenium and total corpus callosum and a higher radial diffusion and lower fractional anisotropy in the splenium of patients presurgery; a lower volume in all substructures in the postsurgery group; higher radial diffusion in the rostral body, body, and splenium; and a higher apparent diffusion coefficient in the splenium of postsurgery patients. Similar fractional anisotropy changes in congenital heart defect patients were reported in preterm infants. Our findings in apparent diffusion coefficient in the splenium of these patients (pre and postsurgery) are comparable to findings in preterm neonates with psychomotor delay. Delayed maturation of the isthmus was also reported in preterm infants. © The Author(s) 2015.

Embolic stroke associated with injection of buprenorphine tablets.

PubMed

Lim, C C Tchoyoson; Lee, Sze Haur; Wong, Yee-Choon; Hui, Francis

2009-09-15

Drug users who crush, dissolve, and inject buprenorphine tablets parenterally may be at risk of severe thromboembolic complications or death. We describe patients with neurologic complications after injecting buprenorphine tablets. Brain MRI including diffusion-weighted imaging (DWI) in patients admitted to the neurologic department after injecting buprenorphine tablets were reviewed. Seven men had neurologic complications after buprenorphine tablet injection. In 5 patients, multiple small scattered hyperintense lesions were detected on DWI in the cortex, white matter, and basal ganglia of the cerebral hemisphere; one patient had a single small lesion. The side of MRI abnormality corresponded to the side of needle marks on the neck except in one patient who had bilateral injections. One patient, who denied injecting into the neck, had DWI abnormalities in the middle cerebral artery territory on one side and occlusion of the ipsilateral internal carotid artery. Buprenorphine tablets can be intentionally or inadvertently injected into the carotid artery, causing a characteristic appearance on diffusion-weighted imaging, consistent with embolic cerebral infarction.

A robust multi-shot scan strategy for high-resolution diffusion weighted MRI enabled by multiplexed sensitivity-encoding (MUSE)

PubMed Central

Chen, Nan-kuei; Guidon, Arnaud; Chang, Hing-Chiu; Song, Allen W.

2013-01-01

Diffusion weighted magnetic resonance imaging (DWI) data have been mostly acquired with single-shot echo-planar imaging (EPI) to minimize motion induced artifacts. The spatial resolution, however, is inherently limited in single-shot EPI, even when the parallel imaging (usually at an acceleration factor of 2) is incorporated. Multi-shot acquisition strategies could potentially achieve higher spatial resolution and fidelity, but they are generally susceptible to motion-induced phase errors among excitations that are exacerbated by diffusion sensitizing gradients, rendering the reconstructed images unusable. It has been shown that shot-to-shot phase variations may be corrected using navigator echoes, but at the cost of imaging throughput. To address these challenges, a novel and robust multi-shot DWI technique, termed multiplexed sensitivity-encoding (MUSE), is developed here to reliably and inherently correct nonlinear shot-to-shot phase variations without the use of navigator echoes. The performance of the MUSE technique is confirmed experimentally in healthy adult volunteers on 3 Tesla MRI systems. This newly developed technique should prove highly valuable for mapping brain structures and connectivities at high spatial resolution for neuroscience studies. PMID:23370063

Assessing liver fibrosis: comparison of arterial enhancement fraction and diffusion-weighted imaging.

PubMed

Bonekamp, David; Bonekamp, Susanne; Ou, Hsin-You; Torbenson, Michael S; Corona-Villalobos, Celia Pamela; Mezey, Esteban; Kamel, Ihab R

2014-11-01

Noninvasive markers have been developed to reduce the need for liver biopsy. The aim of this study was to compare the strength of association of the arterial enhancement fraction (AEF), apparent diffusion coefficient (ADC), and serum biomarkers for staging hepatic fibrosis. Eighty-five patients with chronic liver disease underwent triple-phase contrast-enhanced MRI, used to calculate AEF, and diffusion-weighted MRI (b = 0,750 s/mm(2) ), used to calculate ADC. Hepatic fibrosis was staged according METAVIR criteria. The overall association of the four biomarkers (AEF, ADC, aspartate aminotransferase (AST)/alanine aminotransferase (ALT) ratio, and aspartate aminotransferase to platelet ratio index [APRI]) was compared using nonparametric tests and receiver operating characteristic (ROC) curve, using histopathologic analysis as the reference standard. AEF and ADC values differed significantly between histopathologic fibrosis stages. AEF values correlated with fibrosis stage, ADC values correlated negatively with fibrosis stage. Compared with ADC, AEF showed a trend toward an improved capability of discriminating fibrosis stages. A weighted composite score of AEF and ADC had significantly better diagnostic accuracy than ADC alone (P ≤ 0.023). Imaging parameters had a significantly better diagnostic accuracy than AST/ALT ratio or APRI. AEF may be able to detect the presence of mild, moderate, and advanced liver fibrosis, and its value is increased with concomitant use of ADC. © 2013 Wiley Periodicals, Inc.

1.5 versus 3 versus 7 Tesla in abdominal MRI: A comparative study.

PubMed

Laader, Anja; Beiderwellen, Karsten; Kraff, Oliver; Maderwald, Stefan; Wrede, Karsten; Ladd, Mark E; Lauenstein, Thomas C; Forsting, Michael; Quick, Harald H; Nassenstein, Kai; Umutlu, Lale

2017-01-01

The aim of this study was to investigate and compare the feasibility as well as potential impact of altered magnetic field properties on image quality and potential artifacts of 1.5 Tesla, 3 Tesla and 7 Tesla non-enhanced abdominal MRI. Magnetic Resonance (MR) imaging of the upper abdomen was performed in 10 healthy volunteers on a 1.5 Tesla, a 3 Tesla and a 7 Tesla MR system. The study protocol comprised a (1) T1-weighted fat-saturated spoiled gradient-echo sequence (2D FLASH), (2) T1-weighted fat-saturated volumetric interpolated breath hold examination sequence (3D VIBE), (3) T1-weighted 2D in and opposed phase sequence, (4) True fast imaging with steady-state precession sequence (TrueFISP) and (5) T2-weighted turbo spin-echo (TSE) sequence. For comparison reasons field of view and acquisition times were kept comparable for each correlating sequence at all three field strengths, while trying to achieve the highest possible spatial resolution. Qualitative and quantitative analyses were tested for significant differences. While 1.5 and 3 Tesla MRI revealed comparable results in all assessed features and sequences, 7 Tesla MRI yielded considerable differences in T1 and T2 weighted imaging. Benefits of 7 Tesla MRI encompassed an increased higher spatial resolution and a non-enhanced hyperintense vessel signal at 7 Tesla, potentially offering a more accurate diagnosis of abdominal parenchymatous and vasculature disease. 7 Tesla MRI was also shown to be more impaired by artifacts, including residual B1 inhomogeneities, susceptibility and chemical shift artifacts, resulting in reduced overall image quality and overall image impairment ratings. While 1.5 and 3 Tesla T2w imaging showed equivalently high image quality, 7 Tesla revealed strong impairments in its diagnostic value. Our results demonstrate the feasibility and overall comparable imaging ability of T1-weighted 7 Tesla abdominal MRI towards 3 Tesla and 1.5 Tesla MRI, yielding a promising diagnostic potential for non-enhanced Magnetic Resonance Angiography (MRA). 1.5 Tesla and 3 Tesla offer comparably high-quality T2w imaging, showing superior diagnostic quality over 7 Tesla MRI.

1.5 versus 3 versus 7 Tesla in abdominal MRI: A comparative study

PubMed Central

Beiderwellen, Karsten; Kraff, Oliver; Maderwald, Stefan; Wrede, Karsten; Ladd, Mark E.; Lauenstein, Thomas C.; Forsting, Michael; Quick, Harald H.; Nassenstein, Kai; Umutlu, Lale

2017-01-01

Objectives The aim of this study was to investigate and compare the feasibility as well as potential impact of altered magnetic field properties on image quality and potential artifacts of 1.5 Tesla, 3 Tesla and 7 Tesla non-enhanced abdominal MRI. Materials and methods Magnetic Resonance (MR) imaging of the upper abdomen was performed in 10 healthy volunteers on a 1.5 Tesla, a 3 Tesla and a 7 Tesla MR system. The study protocol comprised a (1) T1-weighted fat-saturated spoiled gradient-echo sequence (2D FLASH), (2) T1-weighted fat-saturated volumetric interpolated breath hold examination sequence (3D VIBE), (3) T1-weighted 2D in and opposed phase sequence, (4) True fast imaging with steady-state precession sequence (TrueFISP) and (5) T2-weighted turbo spin-echo (TSE) sequence. For comparison reasons field of view and acquisition times were kept comparable for each correlating sequence at all three field strengths, while trying to achieve the highest possible spatial resolution. Qualitative and quantitative analyses were tested for significant differences. Results While 1.5 and 3 Tesla MRI revealed comparable results in all assessed features and sequences, 7 Tesla MRI yielded considerable differences in T1 and T2 weighted imaging. Benefits of 7 Tesla MRI encompassed an increased higher spatial resolution and a non-enhanced hyperintense vessel signal at 7 Tesla, potentially offering a more accurate diagnosis of abdominal parenchymatous and vasculature disease. 7 Tesla MRI was also shown to be more impaired by artifacts, including residual B1 inhomogeneities, susceptibility and chemical shift artifacts, resulting in reduced overall image quality and overall image impairment ratings. While 1.5 and 3 Tesla T2w imaging showed equivalently high image quality, 7 Tesla revealed strong impairments in its diagnostic value. Conclusions Our results demonstrate the feasibility and overall comparable imaging ability of T1-weighted 7 Tesla abdominal MRI towards 3 Tesla and 1.5 Tesla MRI, yielding a promising diagnostic potential for non-enhanced Magnetic Resonance Angiography (MRA). 1.5 Tesla and 3 Tesla offer comparably high-quality T2w imaging, showing superior diagnostic quality over 7 Tesla MRI. PMID:29125850

Voxel-based automated detection of focal cortical dysplasia lesions using diffusion tensor imaging and T2-weighted MRI data.

PubMed

Wang, Yanming; Zhou, Yawen; Wang, Huijuan; Cui, Jin; Nguchu, Benedictor Alexander; Zhang, Xufei; Qiu, Bensheng; Wang, Xiaoxiao; Zhu, Mingwang

2018-05-21

The aim of this study was to automatically detect focal cortical dysplasia (FCD) lesions in patients with extratemporal lobe epilepsy by relying on diffusion tensor imaging (DTI) and T2-weighted magnetic resonance imaging (MRI) data. We implemented an automated classifier using voxel-based multimodal features to identify gray and white matter abnormalities of FCD in patient cohorts. In addition to the commonly used T2-weighted image intensity feature, DTI-based features were also utilized. A Gaussian processes for machine learning (GPML) classifier was tested on 12 patients with FCD (8 with histologically confirmed FCD) scanned at 1.5 T and cross-validated using a leave-one-out strategy. Moreover, we compared the multimodal GPML paradigm's performance with that of single modal GPML and classical support vector machine (SVM). Our results demonstrated that the GPML performance on DTI-based features (mean AUC = 0.63) matches with the GPML performance on T2-weighted image intensity feature (mean AUC = 0.64). More promisingly, GPML yielded significantly improved performance (mean AUC = 0.76) when applying DTI-based features to multimodal paradigm. Based on the results, it can also be clearly stated that the proposed GPML strategy performed better and is robust to unbalanced dataset contrary to SVM that performed poorly (AUC = 0.69). Therefore, the GPML paradigm using multimodal MRI data containing DTI modality has promising result towards detection of the FCD lesions and provides an effective direction for future researches. Copyright © 2018 Elsevier Inc. All rights reserved.

Monitoring the development of xenograft triple-negative breast cancer models using diffusion-weighted magnetic resonance imaging.

PubMed

Stephen, Renu M; Pagel, Mark D; Brown, Kathy; Baker, Amanda F; Meuillet, Emmanuelle J; Gillies, Robert J

2012-11-01

Evaluations of tumor growth rates and molecular biomarkers are traditionally used to assess new mouse models of human breast cancers. This study investigated the utility of diffusion weighted (DW)-magnetic resonance imaging (MRI) for evaluating cellular proliferation of new tumor models of triple-negative breast cancer, which may augment traditional analysis methods. Eleven human breast cancer cell lines were used to develop xenograft tumors in severe combined immunodeficient mice, with two of these cell lines exhibiting sufficient growth to be serially passaged. DW-MRI was performed to measure the distributions of the apparent diffusion coefficient (ADC) in these two tumor xenograft models, which showed a correlation with tumor growth rates and doubling times during each passage. The distributions of the ADC values were also correlated with expression of Ki67, a biomarker of cell proliferation, and hypoxia inducible factor (HIF)-1α and vascular endothelial growth factor receptor-2 (VEGFR2), which are essential proteins involved in regulating aerobic glycolysis and angiogenesis that support tumor cell proliferation. Although phosphatase and tensin homolog (PTEN) levels were different between the two xenograft models, AKT levels did not differ nor did they correlate with tumor growth. This last result demonstrates the complexity of signaling protein pathways and the difficulty in interpreting the effects of protein expression on tumor cell proliferation. In contrast, DW-MRI may be a more direct assessment of tumor growth and cancer cell proliferation.

Reduced Field-of-View Diffusion-Weighted Magnetic Resonance Imaging of the Prostate at 3 Tesla: Comparison With Standard Echo-Planar Imaging Technique for Image Quality and Tumor Assessment.

PubMed

Tamada, Tsutomu; Ream, Justin M; Doshi, Ankur M; Taneja, Samir S; Rosenkrantz, Andrew B

The purpose of this study was to compare image quality and tumor assessment at prostate magnetic resonance imaging (MRI) between reduced field-of-view diffusion-weighted imaging (rFOV-DWI) and standard DWI (st-DWI). A total of 49 patients undergoing prostate MRI and MRI/ultrasound fusion-targeted biopsy were included. Examinations included st-DWI (field of view [FOV], 200 × 200 mm) and rFOV-DWI (FOV, 140 × 64 mm) using a 2-dimensional (2D) spatially-selective radiofrequency pulse and parallel transmission. Two readers performed qualitative assessments; a third reader performed quantitative evaluation. Overall image quality, anatomic distortion, visualization of capsule, and visualization of peripheral/transition zone edge were better for rFOV-DWI for reader 1 (P ≤ 0.002), although not for reader 2 (P ≥ 0.567). For both readers, sensitivity, specificity, and accuracy for tumor with a Gleason Score (GS) of 3 + 4 or higher were not different (P ≥ 0.289). Lesion clarity was higher for st-DWI for reader 2 (P = 0.008), although similar for reader 1 (P = 0.409). Diagnostic confidence was not different for either reader (P ≥ 0.052). Tumor-to-benign apparent diffusion coefficient ratio was not different (P = 0.675). Potentially improved image quality of rFOV-DWI did not yield improved tumor assessment. Continued optimization is warranted.

Fiber estimation and tractography in diffusion MRI: Development of simulated brain images and comparison of multi-fiber analysis methods at clinical b-values

PubMed Central

Wilkins, Bryce; Lee, Namgyun; Gajawelli, Niharika; Law, Meng; Leporé, Natasha

2015-01-01

Advances in diffusion-weighted magnetic resonance imaging (DW-MRI) have led to many alternative diffusion sampling strategies and analysis methodologies. A common objective among methods is estimation of white matter fiber orientations within each voxel, as doing so permits in-vivo fiber-tracking and the ability to study brain connectivity and networks. Knowledge of how DW-MRI sampling schemes affect fiber estimation accuracy, and consequently tractography and the ability to recover complex white-matter pathways, as well as differences between results due to choice of analysis method and which method(s) perform optimally for specific data sets, all remain important problems, especially as tractography-based studies become common. In this work we begin to address these concerns by developing sets of simulated diffusion-weighted brain images which we then use to quantitatively evaluate the performance of six DW-MRI analysis methods in terms of estimated fiber orientation accuracy, false-positive (spurious) and false-negative (missing) fiber rates, and fiber-tracking. The analysis methods studied are: 1) a two-compartment “ball and stick” model (BSM) (Behrens et al., 2003); 2) a non-negativity constrained spherical deconvolution (CSD) approach (Tournier et al., 2007); 3) analytical q-ball imaging (QBI) (Descoteaux et al., 2007); 4) q-ball imaging with Funk-Radon and Cosine Transform (FRACT) (Haldar and Leahy, 2013); 5) q-ball imaging within constant solid angle (CSA) (Aganj et al., 2010); and 6) a generalized Fourier transform approach known as generalized q-sampling imaging (GQI) (Yeh et al., 2010). We investigate these methods using 20, 30, 40, 60, 90 and 120 evenly distributed q-space samples of a single shell, and focus on a signal-to-noise ratio (SNR = 18) and diffusion-weighting (b = 1000 s/mm2) common to clinical studies. We found the BSM and CSD methods consistently yielded the least fiber orientation error and simultaneously greatest detection rate of fibers. Fiber detection rate was found to be the most distinguishing characteristic between the methods, and a significant factor for complete recovery of tractography through complex white-matter pathways. For example, while all methods recovered similar tractography of prominent white matter pathways of limited fiber crossing, CSD (which had the highest fiber detection rate, especially for voxels containing three fibers) recovered the greatest number of fibers and largest fraction of correct tractography for a complex three-fiber crossing region. The synthetic data sets, ground-truth, and tools for quantitative evaluation are publically available on the NITRC website as the project “Simulated DW-MRI Brain Data Sets for Quantitative Evaluation of Estimated Fiber Orientations” at http://www.nitrc.org/projects/sim_dwi_brain PMID:25555998

Fiber estimation and tractography in diffusion MRI: development of simulated brain images and comparison of multi-fiber analysis methods at clinical b-values.

PubMed

Wilkins, Bryce; Lee, Namgyun; Gajawelli, Niharika; Law, Meng; Leporé, Natasha

2015-04-01

Advances in diffusion-weighted magnetic resonance imaging (DW-MRI) have led to many alternative diffusion sampling strategies and analysis methodologies. A common objective among methods is estimation of white matter fiber orientations within each voxel, as doing so permits in-vivo fiber-tracking and the ability to study brain connectivity and networks. Knowledge of how DW-MRI sampling schemes affect fiber estimation accuracy, tractography and the ability to recover complex white-matter pathways, differences between results due to choice of analysis method, and which method(s) perform optimally for specific data sets, all remain important problems, especially as tractography-based studies become common. In this work, we begin to address these concerns by developing sets of simulated diffusion-weighted brain images which we then use to quantitatively evaluate the performance of six DW-MRI analysis methods in terms of estimated fiber orientation accuracy, false-positive (spurious) and false-negative (missing) fiber rates, and fiber-tracking. The analysis methods studied are: 1) a two-compartment "ball and stick" model (BSM) (Behrens et al., 2003); 2) a non-negativity constrained spherical deconvolution (CSD) approach (Tournier et al., 2007); 3) analytical q-ball imaging (QBI) (Descoteaux et al., 2007); 4) q-ball imaging with Funk-Radon and Cosine Transform (FRACT) (Haldar and Leahy, 2013); 5) q-ball imaging within constant solid angle (CSA) (Aganj et al., 2010); and 6) a generalized Fourier transform approach known as generalized q-sampling imaging (GQI) (Yeh et al., 2010). We investigate these methods using 20, 30, 40, 60, 90 and 120 evenly distributed q-space samples of a single shell, and focus on a signal-to-noise ratio (SNR = 18) and diffusion-weighting (b = 1000 s/mm(2)) common to clinical studies. We found that the BSM and CSD methods consistently yielded the least fiber orientation error and simultaneously greatest detection rate of fibers. Fiber detection rate was found to be the most distinguishing characteristic between the methods, and a significant factor for complete recovery of tractography through complex white-matter pathways. For example, while all methods recovered similar tractography of prominent white matter pathways of limited fiber crossing, CSD (which had the highest fiber detection rate, especially for voxels containing three fibers) recovered the greatest number of fibers and largest fraction of correct tractography for complex three-fiber crossing regions. The synthetic data sets, ground-truth, and tools for quantitative evaluation are publically available on the NITRC website as the project "Simulated DW-MRI Brain Data Sets for Quantitative Evaluation of Estimated Fiber Orientations" at http://www.nitrc.org/projects/sim_dwi_brain. Copyright © 2014 Elsevier Inc. All rights reserved.

q-Space Upsampling Using x-q Space Regularization.

PubMed

Chen, Geng; Dong, Bin; Zhang, Yong; Shen, Dinggang; Yap, Pew-Thian

2017-09-01

Acquisition time in diffusion MRI increases with the number of diffusion-weighted images that need to be acquired. Particularly in clinical settings, scan time is limited and only a sparse coverage of the vast q -space is possible. In this paper, we show how non-local self-similar information in the x - q space of diffusion MRI data can be harnessed for q -space upsampling. More specifically, we establish the relationships between signal measurements in x - q space using a patch matching mechanism that caters to unstructured data. We then encode these relationships in a graph and use it to regularize an inverse problem associated with recovering a high q -space resolution dataset from its low-resolution counterpart. Experimental results indicate that the high-resolution datasets reconstructed using the proposed method exhibit greater quality, both quantitatively and qualitatively, than those obtained using conventional methods, such as interpolation using spherical radial basis functions (SRBFs).

Test-retest reliability and repeatability of renal diffusion tensor MRI in healthy subjects.

PubMed

Cutajar, Marica; Clayden, Jonathan D; Clark, Christopher A; Gordon, Isky

2011-12-01

This study assessed test-retest reliability and repeatability of diffusion tensor imaging (DTI) in the kidneys. Seven healthy volunteers (age range, 19-31 years), were imaged three consecutive times on the same day (short-term reliability) and the same imaging protocol was repeated after a month (long-term reliability). Diffusion-weighted magnetic resonance imaging scans in the coronal-oblique projection of the kidney were acquired on a 1.5 T scanner using a multi-section echo-planar sequence; six contiguous slices each 5 mm thick, diffusion sensitisation along 20 non-collinear directions, TR=730 ms, TE=73 ms and 2 b-values (0 and 400 s mm(-2)). Volunteers were asked to hold their breath throughout each data acquisition (approx. 20 s). The apparent diffusion coefficient (ADC) and fractional anisotropy (FA) values were obtained from maps generated using dedicated software MIStar (Apollo Medical Imaging, Melbourne, Australia). Statistical analyses of both short- and long-term repeats were carried out from which the within-subject coefficient of variation (wsCV) was calculated. The wsCV obtained for both the ADC and FA values were less than 10% in all the analyses carried out. In addition, paired (repeated measures) t-test was used to measure the variation between the diffusion parameters collected from the two scanning sessions a month apart. It showed no significant difference and the wsCV obtained after comparing the first and second scans were found to be smaller than 15% for both ADC and FA. Renal DTI produces reliable and repeatable results which make longitudinal investigation of patients viable. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

High b Value (2,000 s/mm2) Diffusion-Weighted Magnetic Resonance Imaging in Prostate Cancer at 3 Tesla: Comparison with 1,000 s/mm2 for Tumor Conspicuity and Discrimination of Aggressiveness

PubMed Central

Tamada, Tsutomu; Kanomata, Naoki; Sone, Teruki; Jo, Yoshimasa; Miyaji, Yoshiyuki; Higashi, Hiroki; Yamamoto, Akira; Ito, Katsuyoshi

2014-01-01

Objective The objective of our study was to investigate tumor conspicuity and the discrimination potential for tumor aggressiveness on diffusion-weighted magnetic resonance imaging (DW-MRI) with high b value at 3-T. Materials and Methods The institutional review board approved this study and waived the requirement for informed consent. A total of 50 patients with prostate cancer (69 cancer foci; 48 in the PZ, 20 in the TZ, and one in whole prostate) who underwent multiparametric prostate MRI including DW-MRI (b values: 0, 1000 s/mm2 and 0, 2000 s/mm2) on a 3-T system were included. Lesion conspicuity score (LCS) using visual assessment (1 = invisible for surrounding normal site; 2 = slightly high intensity; 3 = moderately high; and 4 = very high) and tumor-normal signal intensity ratio (TNR) were assessed, and apparent diffusion coefficient (ADC, ×10−3 mm2/s) of the tumor regions and normal regions were measured. Results Mean LCS and TNR at 0, 2000 s/mm2 was significantly higher than those at 0, 1000 s/mm2 (p<0.001 for both). In addition, ADC at both 0, 1000 and 0, 2000 s/mm2 was found to distinguish intermediate or high risk cancer with Gleason score ≥7 from low risk cancer with Gleason score ≤6 (p<0.001 for both). Furthermore, ADC of tumor regions correlated with Gleason score at both 0, 1000 s/mm2 (ρ = −0.602; p<0.001) and 0, 2000 s/mm2 (ρ = −0.645; p<0.001). Conclusions For tumor conspicuity and characterization of prostate cancer on DW-MRI of 3-T MRI, b = 0, 2000 s/mm2 is more useful than b = 0, 1000 s/mm2. PMID:24802652

High b value (2,000 s/mm2) diffusion-weighted magnetic resonance imaging in prostate cancer at 3 Tesla: comparison with 1,000 s/mm2 for tumor conspicuity and discrimination of aggressiveness.

PubMed

Tamada, Tsutomu; Kanomata, Naoki; Sone, Teruki; Jo, Yoshimasa; Miyaji, Yoshiyuki; Higashi, Hiroki; Yamamoto, Akira; Ito, Katsuyoshi

2014-01-01

The objective of our study was to investigate tumor conspicuity and the discrimination potential for tumor aggressiveness on diffusion-weighted magnetic resonance imaging (DW-MRI) with high b value at 3-T. The institutional review board approved this study and waived the requirement for informed consent. A total of 50 patients with prostate cancer (69 cancer foci; 48 in the PZ, 20 in the TZ, and one in whole prostate) who underwent multiparametric prostate MRI including DW-MRI (b values: 0, 1000 s/mm2 and 0, 2000 s/mm2) on a 3-T system were included. Lesion conspicuity score (LCS) using visual assessment (1 = invisible for surrounding normal site; 2 = slightly high intensity; 3 = moderately high; and 4 = very high) and tumor-normal signal intensity ratio (TNR) were assessed, and apparent diffusion coefficient (ADC, ×10-3 mm2/s) of the tumor regions and normal regions were measured. Mean LCS and TNR at 0, 2000 s/mm2 was significantly higher than those at 0, 1000 s/mm2 (p<0.001 for both). In addition, ADC at both 0, 1000 and 0, 2000 s/mm2 was found to distinguish intermediate or high risk cancer with Gleason score ≥7 from low risk cancer with Gleason score ≤6 (p<0.001 for both). Furthermore, ADC of tumor regions correlated with Gleason score at both 0, 1000 s/mm2 (ρ = -0.602; p<0.001) and 0, 2000 s/mm2 (ρ = -0.645; p<0.001). For tumor conspicuity and characterization of prostate cancer on DW-MRI of 3-T MRI, b = 0, 2000 s/mm2 is more useful than b = 0, 1000 s/mm2.

Tissue microstructure estimation using a deep network inspired by a dictionary-based framework.

PubMed

Ye, Chuyang

2017-12-01

Diffusion magnetic resonance imaging (dMRI) captures the anisotropic pattern of water displacement in the neuronal tissue and allows noninvasive investigation of the complex tissue microstructure. A number of biophysical models have been proposed to relate the tissue organization with the observed diffusion signals, so that the tissue microstructure can be inferred. The Neurite Orientation Dispersion and Density Imaging (NODDI) model has been a popular choice and has been widely used for many neuroscientific studies. It models the diffusion signal with three compartments that are characterized by distinct diffusion properties, and the parameters in the model describe tissue microstructure. In NODDI, these parameters are estimated in a maximum likelihood framework, where the nonlinear model fitting is computationally intensive. Therefore, efforts have been made to develop efficient and accurate algorithms for NODDI microstructure estimation, which is still an open problem. In this work, we propose a deep network based approach that performs end-to-end estimation of NODDI microstructure, which is named Microstructure Estimation using a Deep Network (MEDN). MEDN comprises two cascaded stages and is motivated by the AMICO algorithm, where the NODDI microstructure estimation is formulated in a dictionary-based framework. The first stage computes the coefficients of the dictionary. It resembles the solution to a sparse reconstruction problem, where the iterative process in conventional estimation approaches is unfolded and truncated, and the weights are learned instead of predetermined by the dictionary. In the second stage, microstructure properties are computed from the output of the first stage, which resembles the weighted sum of normalized dictionary coefficients in AMICO, and the weights are also learned. Because spatial consistency of diffusion signals can be used to reduce the effect of noise, we also propose MEDN+, which is an extended version of MEDN. MEDN+ allows incorporation of neighborhood information by inserting a stage with learned weights before the MEDN structure, where the diffusion signals in the neighborhood of a voxel are processed. The weights in MEDN or MEDN+ are jointly learned from training samples that are acquired with diffusion gradients densely sampling the q-space. We performed MEDN and MEDN+ on brain dMRI scans, where two shells each with 30 gradient directions were used, and measured their accuracy with respect to the gold standard. Results demonstrate that the proposed networks outperform the competing methods. Copyright © 2017 Elsevier B.V. All rights reserved.

Incomplete initial nutation diffusion imaging: An ultrafast, single-scan approach for diffusion mapping.

PubMed

Ianuş, Andrada; Shemesh, Noam

2018-04-01

Diffusion MRI is confounded by the need to acquire at least two images separated by a repetition time, thereby thwarting the detection of rapid dynamic microstructural changes. The issue is exacerbated when diffusivity variations are accompanied by rapid changes in T 2 . The purpose of the present study is to accelerate diffusion MRI acquisitions such that both reference and diffusion-weighted images necessary for quantitative diffusivity mapping are acquired in a single-shot experiment. A general methodology termed incomplete initial nutation diffusion imaging (INDI), capturing two diffusion contrasts in a single shot, is presented. This methodology creates a longitudinal magnetization reservoir that facilitates the successive acquisition of two images separated by only a few milliseconds. The theory behind INDI is presented, followed by proof-of-concept studies in water phantom, ex vivo, and in vivo experiments at 16.4 and 9.4 T. Mean diffusivities extracted from INDI were comparable with diffusion tensor imaging and the two-shot isotropic diffusion encoding in the water phantom. In ex vivo mouse brain tissues, as well as in the in vivo mouse brain, mean diffusivities extracted from conventional isotropic diffusion encoding and INDI were in excellent agreement. Simulations for signal-to-noise considerations identified the regimes in which INDI is most beneficial. The INDI method accelerates diffusion MRI acquisition to single-shot mode, which can be of great importance for mapping dynamic microstructural properties in vivo without T 2 bias. Magn Reson Med 79:2198-2204, 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 properly cited. © 2017 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine.

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

DTIC Science & Technology

2014-10-01

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

Contribution of diffusion weighted MRI to diagnosis and staging in gastric tumors and comparison with multi-detector computed tomography.

PubMed

Arslan, Harun; Fatih Özbay, Mehmet; Çallı, İskan; Doğan, Erkan; Çelik, Sebahattin; Batur, Abdussamet; Bora, Aydın; Yavuz, Alpaslan; Bulut, Mehmet Deniz; Özgökçe, Mesut; Çetin Kotan, Mehmet

2017-03-01

Diagnostic performance of Diffusion-Weighted magnetic resonance Imaging (DWI) and Multi-Detector Computed Tomography (MDCT) for TNM (Tumor, Lymph node, Metastasis) staging of gastric cancer was compared. We used axial T2-weighted images and DWI (b-0,400 and b-800 s/mm2) protocol on 51 pre-operative patients who had been diagnosed with gastric cancer. We also conducted MDCT examinations on them. We looked for a signal increase in the series of DWI images. The depth of tumor invasion in the stomach wall (tumor (T) staging), the involvement of lymph nodes (nodal (N) staging), and the presence or absence of metastases (metastatic staging) in DWI and CT images according to the TNM staging system were evaluated. In each diagnosis of the tumors, sensitivity, specificity, positive and negative accuracy rates of DWI and MDCT examinations were found through a comparison with the results of the surgical pathology, which is the gold standard method. In addition to the compatibilities of each examination with surgical pathology, kappa statistics were used. Sensitivity and specificity of DWI and MDCT in lymph node staging were as follows: N1: DWI: 75.0%, 84.6%; MDCT: 66.7%, 82%;N2: DWI: 79.3%, 77.3%; MDCT: 69.0%, 68.2%; N3: DWI: 60.0%, 97.6%; MDCT: 50.0%, 90.2%. The diagnostic tool DWI seemed more compatible with the gold standard method (surgical pathology), especially in the staging of lymph node, when compared to MDCT. On the other hand, in T staging, the results of DWI and MDCT were better than the gold standard when the T stage increased. However, DWI did not demonstrate superiority to MDCT. The sensitivity and specificity of both imaging techniques for detecting distant metastasis were 100%. The diagnostic accuracy of DWI for TNM staging in gastric cancer before surgery is at a comparable level with MDCT and adding DWI to routine protocol of evaluating lymph nodes metastasis might increase diagnostic accuracy.

Computer-aided Detection of Prostate Cancer with MRI: Technology and Applications.

PubMed

Liu, Lizhi; Tian, Zhiqiang; Zhang, Zhenfeng; Fei, Baowei

2016-08-01

One in six men will develop prostate cancer in his lifetime. Early detection and accurate diagnosis of the disease can improve cancer survival and reduce treatment costs. Recently, imaging of prostate cancer has greatly advanced since the introduction of multiparametric magnetic resonance imaging (mp-MRI). Mp-MRI consists of T2-weighted sequences combined with functional sequences including dynamic contrast-enhanced MRI, diffusion-weighted MRI, and magnetic resonance spectroscopy imaging. Because of the big data and variations in imaging sequences, detection can be affected by multiple factors such as observer variability and visibility and complexity of the lesions. To improve quantitative assessment of the disease, various computer-aided detection systems have been designed to help radiologists in their clinical practice. This review paper presents an overview of literatures on computer-aided detection of prostate cancer with mp-MRI, which include the technology and its applications. The aim of the survey is threefold: an introduction for those new to the field, an overview for those working in the field, and a reference for those searching for literature on a specific application. Copyright © 2016 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.

Differentiation between phyllodes tumours and fibroadenomas using intravoxel incoherent motion magnetic resonance imaging: comparison with conventional diffusion-weighted imaging.

PubMed

Kawashima, Hiroko; Miyati, Tosiaki; Ohno, Naoki; Ohno, Masako; Inokuchi, Masafumi; Ikeda, Hiroko; Gabata, Toshifumi

2018-04-01

To investigate whether the parameters derived from intravoxel incoherent motion (IVIM) MRI could differentiate phyllodes tumours (PTs) from fibroadenomas (FAs) by comparing the apparent diffusion coefficient (ADC) values. This retrospective study included 7 FAs, 10 benign PTs (BPTs), 4 borderline PTs, and one malignant PT. Biexponential analyses of IVIM were performed using a 3 T MRI scanner. Quantitative IVIM parameters [pure diffusion coefficient (D), perfusion-related diffusion coefficient (D*), and fraction (f)] were calculated. The ADC was also calculated using monoexponential fitting. The D and ADC values showed an increasing tendency in the order of FA, BPT, and borderline or malignant PT (BMPT). No significant difference was found in the D value among the three groups. The ADC value of the BMPT group was significantly higher than that of the FA group (p = 0.048). The D* value showed an increasing tendency in the order of BMPT, BPT, and FA, and the D* value of the BMPT group was significantly lower than that of the FA group (p = 0.048). The D* derived from IVIM and the ADC were helpful for differentiating between FA and BMPT. Advances in knowledge: IVIM MRI examination showed that the perfusion-related diffusion coefficient is lower in borderline and malignant PTs than in FAs and the opposite is true for the ADC.

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.

PubMed

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.

Pulmonary 3He Magnetic Resonance Imaging Biomarkers of Regional Airspace Enlargement in Alpha-1 Antitrypsin Deficiency.

PubMed

Lessard, Eric; Young, Heather M; Bhalla, Anurag; Pike, Damien; Sheikh, Khadija; McCormack, David G; Ouriadov, Alexei; Parraga, Grace

2017-11-01

Thoracic x-ray computed tomography (CT) and hyperpolarized 3 He magnetic resonance imaging (MRI) provide quantitative measurements of airspace enlargement in patients with emphysema. For patients with panlobular emphysema due to alpha-1 antitrypsin deficiency (AATD), sensitive biomarkers of disease progression and response to therapy have been difficult to develop and exploit, especially those biomarkers that correlate with outcomes like quality of life. Here, our objective was to generate and compare CT and diffusion-weighted inhaled-gas MRI measurements of emphysema including apparent diffusion coefficient (ADC) and MRI-derived mean linear intercept (L m ) in patients with AATD, chronic obstructive pulmonary disease (COPD) ex-smokers, and elderly never-smokers. We enrolled patients with AATD (n = 8; 57 ± 7 years), ex-smokers with COPD (n = 8; 77 ± 6 years), and a control group of never-smokers (n = 5; 64 ± 2 years) who underwent thoracic CT, MRI, spirometry, plethysmography, the St. George's Respiratory Questionnaire, and the 6-minute walk test during a single 2-hour visit. MRI-derived ADC, L m , surface-to-volume ratio, and ventilation defect percent were generated for the apical, basal, and whole lung as was CT lung area ≤-950 Hounsfield units (RA 950 ), low attenuating clusters, and airway count. In patients with AATD, there was a significantly different MRI-derived ADC (P = .03), L m (P < .0001), and surface-to-volume ratio (P < .0001), but not diffusing capacity of carbon monoxide, residual volume or total lung capacity, or CT RA 950 (P > .05) compared to COPD ex-smokers with a significantly different St. George's Respiratory Questionnaire. In this proof-of-concept demonstration, we evaluated CT and MRI lung emphysema measurements and observed significantly worse MRI biomarkers of emphysema in patients with AATD compared to patients with COPD, although CT RA 950 and diffusing capacity of carbon monoxide were not significantly different, underscoring the sensitivity of MRI measurements of AATD emphysema. Copyright © 2017 The Association of University Radiologists. Published by Elsevier Inc. All rights reserved.

MRI and clinical features of maple syrup urine disease: preliminary results in 10 cases

PubMed Central

Cheng, Ailan; Han, Lianshu; Feng, Yun; Li, Huimin; Yao, Rong; Wang, Dengbin; Jin, Biao

2017-01-01

PURPOSE We aimed to evaluate the magnetic resonance imaging (MRI) and clinical features of maple syrup urine disease (MSUD). METHODS This retrospective study consisted of 10 MSUD patients confirmed by genetic testing. All patients underwent brain MRI. Phenotype, genotype, and areas of brain injury on MRI were retrospectively reviewed. RESULTS Six patients (60%) had the classic form of MSUD with BCKDHB mutation, three patients (30%) had the intermittent form (two with BCKDHA mutations and one with DBT mutation), and one patient (10%) had the thiamine-responsive form with DBT mutation. On diffusion-weighted imaging, nine cases presented restricted diffusion in myelinated areas, and one intermittent case with DBT mutation was normal. The classic form of MSUD involved the basal ganglia in six cases; the cerebellum, mesencephalon, pons, and supratentorial area in five cases; and the thalamus in four cases, respectively. The intermittent form involved the cerebellum, pons, and supratentorial area in two cases. The thiamine-responsive form involved the basal ganglia and supratentorial area. CONCLUSION Our preliminary results indicate that patients with MSUD presented more commonly in classic form with BCKDHB mutation and displayed extensive brain injury on MRI. PMID:28830848

[The diagnostic value of dual-energy CT and 3 Tesla MRI in the diagnosis of German Mardi Gras donuts--where is the mustard, where is the custard and where is the jam?].

PubMed

Morhard, D; Dietrich, O; Reiser, M; Ertl-Wagner, B

2008-04-01

As a Mardi Gras joke, the original jam or custard fillings of German Mardi Gras donuts are frequently replaced with mustard which cannot be identified on the outside of the donut. The aim of our study was to evaluate the impact of modern CT and MRI techniques on the diagnostic evaluation of donuts filled with mustard, jam or custard. 4 commercially available donuts were included in the study. One was filled with custard (PK) and one with jam (MK). Two donuts were specifically prepared and filled with Bavarian mustard (SK1) or extra-hot (SK2) mustard. 3 Tesla MRI was performed with T 2- and T 1-weighted STIR, diffusion and susceptibility-weighted (SWI) sequences. In addition, the donuts underwent dual-energy CT. PK was able to be easily differentiated from the other donuts due to its hyperintensity in the STIR sequences and hypointensity in the T 1-weighted sequences. MK was able to be differentiated from S 1K and S 2K on the basis of its diffusion properties. S 1K demonstrated a pronounced heterogeneity of its matrix, especially in SWI. In CT, PK showed a pronounced hypoattenuation with negative Hounsfield units in contrast to the strongly hyperdense MK, S 1K and S 2K. S 1K and S 2K demonstrated X-ray attenuation considerably dependent on the X-ray energy. Donuts filled with jam, custard or mustard can be readily differentiated by modern MRI and CT techniques. Therefore, eating a mustard-filled donut can be reliably avoided.

Assessment of tumor response to oxygen challenge using quantitative diffusion MRI in an animal model.

PubMed

Zhang, Zhongwei; Yuan, Qing; Zhou, Heling; Zhao, Dawen; Li, Li; Gerberich, Jenifer L; Mason, Ralph P

2015-11-01

To assess tumor response to oxygen challenge using quantitative diffusion magnetic resonance imaging (MRI). A well-characterized Dunning R3327-AT1 rat prostate cancer line was implanted subcutaneously in the right thigh of male Copenhagen rats (n = 8). Diffusion-weighted images (DWI) with multiple b values (0, 25, 50, 100, 150, 200, 300, 500, 1000, 1500 s/mm(2) ) in three orthogonal directions were obtained using a multishot FSE-based Stejskal-Tanner DWI sequence (FSE-DWI) at 4.7T, while rats breathed medical air (21% oxygen) and with 100% oxygen challenge. Stretched-exponential and intravoxel incoherent motion (IVIM) models were used to calculate and compare quantitative diffusion parameters: diffusion heterogeneity index (α), intravoxel distribution of diffusion coefficients (DDC), tissue diffusivity (Dt), pseudo-diffusivity (Dp), and perfusion fraction (f) on a voxel-by-voxel basis. A significant increase of α (73.9 ± 4.7% in air vs. 78.1 ± 4.5% in oxygen, P = 0.0198) and a significant decrease of f (13.4 ± 3.7% in air vs. 10.4 ± 2.7% in oxygen, P = 0.0201) were observed to accompany oxygen challenge. Correlations between f and α during both air and oxygen breathing were found; the correlation coefficients (r) were -0.90 and -0.96, respectively. Positive correlations between Dt and DDC with oxygen breathing (r = 0.95, P = 0.0003), f and DDC with air breathing were also observed (r = 0.95, P = 0.0004). Quantitative diffusion MRI demonstrated changes in tumor perfusion in response to oxygen challenge. © 2015 Wiley Periodicals, Inc.

Multiparametric or practical quantitative liver MRI: towards millisecond, fat fraction, kilopascal and function era.

PubMed

Unal, Emre; Idilman, Ilkay Sedakat; Karçaaltıncaba, Muşturay

2017-02-01

New advances in liver magnetic resonance imaging (MRI) may enable diagnosis of unseen pathologies by conventional techniques. Normal T1 (550-620 ms for 1.5 T and 700-850 ms for 3 T), T2, T2* (>20 ms), T1rho (40-50 ms) mapping, proton density fat fraction (PDFF) (≤5%) and stiffness (2-3kPa) values can enable differentiation of a normal liver from chronic liver and diffuse diseases. Gd-EOB-DTPA can enable assessment of liver function by using postcontrast hepatobiliary phase or T1 reduction rate (normally above 60%). T1 mapping can be important for the assessment of fibrosis, amyloidosis and copper overload. T1rho mapping is promising for the assessment of liver collagen deposition. PDFF can allow objective treatment assessment in NAFLD and NASH patients. T2 and T2* are used for iron overload determination. MR fingerprinting may enable single slice acquisition and easy implementation of multiparametric MRI and follow-up of patients. Areas covered: T1, T2, T2*, PDFF and stiffness, diffusion weighted imaging, intravoxel incoherent motion imaging (ADC, D, D* and f values) and function analysis are reviewed. Expert commentary: Multiparametric MRI can enable biopsyless diagnosis and more objective staging of diffuse liver disease, cirrhosis and predisposing diseases. A comprehensive approach is needed to understand and overcome the effects of iron, fat, fibrosis, edema, inflammation and copper on MR relaxometry values in diffuse liver disease.

A comparative quantitative analysis of magnetic susceptibility artifacts in echo planar and PROPELLER diffusion-weighted images

NASA Astrophysics Data System (ADS)

Cho, Jae-Hwan; Lee, Hae-Kag; Yang, Han-Joon; Lee, Gui-Won; Park, Yong-Soon; Chung, Woon-Kwan

2013-01-01

In this study, the authors investigated whether periodically-rotated overlapping parallel lines with enhanced reconstruction (PROPELLER) diffusion-weighted imaging (DWI) can remove magnetic susceptibility artifacts and compared apparent diffusion coefficient (ADC) values for PROPELLER DWI and the common echo planar (EP) DWI. Twenty patients that underwent brain MRI with a metal dental implant were selected. A 3.0T MR scanner was then used to obtain EP DWI, PROPELLER DWI, and corresponding apparent diffusion coefficient (ADC) maps for a b-value of 0 and 1,000 s/mm2. The frequencies of magnetic susceptibility artifacts in four parts of the brain (bilateral temporal lobes, pons, and orbit) were selected. In the ADC maps, we measured the ADC values of both sides of the temporal lobe and the pons. According to the study results, the frequency of magnetic susceptibility artifacts in PROPELLER DW images was lower than it was in EP DW images. In ADC maps, the ADC values of the bilateral temporal lobes and the pons were all higher in PROPELLER ADC maps than in EP ADC maps. Our findings show that when a high-field MRI machine is used, magnetic susceptibility artifacts can distort anatomical structures and produce high-intensity signals. Furthermore, our findings suggest that in many cases, PROPELLER DWI would be helpful in terms of achieving a correct diagnosis.

Higher-Order Motion-Compensation for In Vivo Cardiac Diffusion Tensor Imaging in Rats

PubMed Central

Welsh, Christopher L.; DiBella, Edward V. R.; Hsu, Edward W.

2015-01-01

Motion of the heart has complicated in vivo applications of cardiac diffusion MRI and diffusion tensor imaging (DTI), especially in small animals such as rats where ultra-high-performance gradient sets are currently not available. Even with velocity compensation via, for example, bipolar encoding pulses, the variable shot-to-shot residual motion-induced spin phase can still give rise to pronounced artifacts. This study presents diffusion-encoding schemes that are designed to compensate for higher-order motion components, including acceleration and jerk, which also have the desirable practical features of minimal TEs and high achievable b-values. The effectiveness of these schemes was verified numerically on a realistic beating heart phantom, and demonstrated empirically with in vivo cardiac diffusion MRI in rats. Compensation for acceleration, and lower motion components, was found to be both necessary and sufficient for obtaining diffusion-weighted images of acceptable quality and SNR, which yielded the first in vivo cardiac DTI demonstrated in the rat. These findings suggest that compensation for higher order motion, particularly acceleration, can be an effective alternative solution to high-performance gradient hardware for improving in vivo cardiac DTI. PMID:25775486

Sedation protocol with fasting and shorter sleep leads to magnetic resonance imaging success.

PubMed

Kimiya, Takahisa; Sekiguchi, Shinichiro; Yagihashi, Tatsuhiko; Arai, Mie; Takahashi, Hirotaka; Takahashi, Takao

2017-10-01

Young children undergoing magnetic resonance imaging (MRI) require sedation. In June 2013, Tokyo Metropolitan Ohtsuka Hospital (TMOH) introduced an oral sedation protocol for young children undergoing MRI; the protocol included instructions on fasting before sedation, and recommended a shorter duration of sleep the night before MRI. We compared the MRI success rate before and after the introduction of this protocol. The eligible subjects were children under 3 years old who underwent MRI by appointment at TMOH between October 2012 and March 2014, under sedation with triclofos sodium. All those who underwent MRI in or after June 2013 were enrolled prospectively as a post-protocol group. All patients who underwent MRI before June 2013 were enrolled retrospectively as a pre-protocol group, with data collected from chart review. Seventy-four patients were enrolled in the post-protocol group, and 42 in the pre-protocol group. The MRI success rate was significantly higher in the post-protocol group than in the pre-protocol group (98.7% vs 88.1%), as was the rate of on-time starting of MRI (86.5% vs 71.4%). The post-protocol group woke up earlier on the day of examination (6:18 a.m. vs 6:43 a.m.), resulting in a significantly longer time between awakening and the beginning of sedation (289.8 min vs 265.9 min), and a significantly shorter average duration of sleep on the previous night (504.8 min vs 532.3 min). Implementation of a hospital-wide sedation protocol for young children undergoing MRI significantly improved the MRI success rate. © 2017 Japan Pediatric Society.

Multi-parametric spinal cord MRI as potential progression marker in amyotrophic lateral sclerosis.

PubMed

El Mendili, Mohamed-Mounir; Cohen-Adad, Julien; Pelegrini-Issac, Mélanie; Rossignol, Serge; Morizot-Koutlidis, Régine; Marchand-Pauvert, Véronique; Iglesias, Caroline; Sangari, Sina; Katz, Rose; Lehericy, Stéphane; Benali, Habib; Pradat, Pierre-François

2014-01-01

To evaluate multimodal MRI of the spinal cord in predicting disease progression and one-year clinical status in amyotrophic lateral sclerosis (ALS) patients. After a first MRI (MRI1), 29 ALS patients were clinically followed during 12 months; 14/29 patients underwent a second MRI (MRI2) at 11±3 months. Cross-sectional area (CSA) that has been shown to be a marker of lower motor neuron degeneration was measured in cervical and upper thoracic spinal cord from T2-weighted images. Fractional anisotropy (FA), axial/radial/mean diffusivities (λ⊥, λ//, MD) and magnetization transfer ratio (MTR) were measured within the lateral corticospinal tract in the cervical region. Imaging metrics were compared with clinical scales: Revised ALS Functional Rating Scale (ALSFRS-R) and manual muscle testing (MMT) score. At MRI1, CSA correlated significantly (P<0.05) with MMT and arm ALSFRS-R scores. FA correlated significantly with leg ALFSRS-R scores. One year after MRI1, CSA predicted (P<0.01) arm ALSFSR-R subscore and FA predicted (P<0.01) leg ALSFRS-R subscore. From MRI1 to MRI2, significant changes (P<0.01) were detected for CSA and MTR. CSA rate of change (i.e. atrophy) highly correlated (P<0.01) with arm ALSFRS-R and arm MMT subscores rate of change. Atrophy and DTI metrics predicted ALS disease progression. Cord atrophy was a better biomarker of disease progression than diffusion and MTR. Our study suggests that multimodal MRI could provide surrogate markers of ALS that may help monitoring the effect of disease-modifying drugs.

The Role of Apparent Diffusion Coefficient Quantification in Differentiating Benign and Malignant Renal Masses by 3 Tesla Magnetic Resonance Imaging.

PubMed

Göya, Cemil; Hamidi, Cihad; Bozkurt, Yaşar; Yavuz, Alpaslan; Kuday, Suzan; Gümüş, Hatice; Türkçü, Gül; Hattapoğlu, Salih; Bilici, Aslan

2015-07-01

Diffusion-weighted magnetic resonance imaging (DWI) is a widely-accepted diagnostic modality whose efficacy has been investigated by numerous past studies in the differentiation of malignant lesions from benign entities. The aim of this study was to evaluate the efficiency of diffusion-weighted magnetic resonance imaging in the characterization of renal lesions. Diagnostic accuracy study. A total of 137 patients with renal lesions were included in this study. The median apparent diffusion coefficient (ADC) values as well as the b 800 and b 1600 signal intensities of normal kidneys, solid components of mixed renal masses, and total cystic lesions were evaluated. There were significant differences between the ADC values of lesions and normal renal parenchyma, and between the ADC values of benign and malignant renal lesions on DWIs at b values of 800 and 1600 s/mm(2) (p<0.001 and p<0.001, respectively). There were significant differences between the ADC values of Bosniak Category 1 and 2 cysts and the ADC values of Bosniak Category 1 and 3 cysts on DWIs at b values of 800 s/mm(2) (p<0.001) and 1600 s/mm(2) (p<0.001). A cutoff value of 1.902 × 10(-3) mm(2)/s for the ADC with a b value of 800 s/mm(2) provided 88% sensitivity and 96% specificity for differentiation between benign and malignant renal lesions. A cutoff value of 1.623 × 10(-3) mm(2)/s for the ADC with a b value of 1600 s/mm(2) provided 79% sensitivity and 96% specificity (p<0.001) for the differentiation between benign and malignant renal lesions. Accurate assessment of renal masses is important for determining the necessity for surgical intervention. DWI provides additional value by differentiating benign from malignant renal tumors and can be added to routine kidney MRI protocols.

Comparison of [{sup 11}C]choline Positron Emission Tomography With T2- and Diffusion-Weighted Magnetic Resonance Imaging for Delineating Malignant Intraprostatic Lesions

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

Chang, Joe H.; University of Melbourne, Victoria; Lim Joon, Daryl

2015-06-01

Purpose: The purpose of this study was to compare the accuracy of [{sup 11}C]choline positron emission tomography (CHOL-PET) with that of the combination of T2-weighted and diffusion-weighted (T2W/DW) magnetic resonance imaging (MRI) for delineating malignant intraprostatic lesions (IPLs) for guiding focal therapies and to investigate factors predicting the accuracy of CHOL-PET. Methods and Materials: This study included 21 patients who underwent CHOL-PET and T2W/DW MRI prior to radical prostatectomy. Two observers manually delineated IPL contours for each scan, and automatic IPL contours were generated on CHOL-PET based on varying proportions of the maximum standardized uptake value (SUV). IPLs identified onmore » prostatectomy specimens defined reference standard contours. The imaging-based contours were compared with the reference standard contours using Dice similarity coefficient (DSC), and sensitivity and specificity values. Factors that could potentially predict the DSC of the best contouring method were analyzed using linear models. Results: The best automatic contouring method, 60% of the maximum SUV (SUV{sub 60}) , had similar correlations (DSC: 0.59) with the manual PET contours (DSC: 0.52, P=.127) and significantly better correlations than the manual MRI contours (DSC: 0.37, P<.001). The sensitivity and specificity values were 72% and 71% for SUV{sub 60}; 53% and 86% for PET manual contouring; and 28% and 92% for MRI manual contouring. The tumor volume and transition zone pattern could independently predict the accuracy of CHOL-PET. Conclusions: CHOL-PET is superior to the combination of T2W/DW MRI for delineating IPLs. The accuracy of CHOL-PET is insufficient for gland-sparing focal therapies but may be accurate enough for focal boost therapies. The transition zone pattern is a new classification that may predict how well CHOL-PET delineates IPLs.« less

ProstateAnalyzer: Web-based medical application for the management of prostate cancer using multiparametric MR imaging.

PubMed

Mata, Christian; Walker, Paul M; Oliver, Arnau; Brunotte, François; Martí, Joan; Lalande, Alain

2016-01-01

In this paper, we present ProstateAnalyzer, a new web-based medical tool for prostate cancer diagnosis. ProstateAnalyzer allows the visualization and analysis of magnetic resonance images (MRI) in a single framework. ProstateAnalyzer recovers the data from a PACS server and displays all the associated MRI images in the same framework, usually consisting of 3D T2-weighted imaging for anatomy, dynamic contrast-enhanced MRI for perfusion, diffusion-weighted imaging in the form of an apparent diffusion coefficient (ADC) map and MR Spectroscopy. ProstateAnalyzer allows annotating regions of interest in a sequence and propagates them to the others. From a representative case, the results using the four visualization platforms are fully detailed, showing the interaction among them. The tool has been implemented as a Java-based applet application to facilitate the portability of the tool to the different computer architectures and software and allowing the possibility to work remotely via the web. ProstateAnalyzer enables experts to manage prostate cancer patient data set more efficiently. The tool allows delineating annotations by experts and displays all the required information for use in diagnosis. According to the current European Society of Urogenital Radiology guidelines, it also includes the PI-RADS structured reporting scheme.

Apparent diffusion coefficient is highly reproducible on preclinical imaging systems: Evidence from a seven-center multivendor study.

PubMed

Doblas, Sabrina; Almeida, Gilberto S; Blé, François-Xavier; Garteiser, Philippe; Hoff, Benjamin A; McIntyre, Dominick J O; Wachsmuth, Lydia; Chenevert, Thomas L; Faber, Cornelius; Griffiths, John R; Jacobs, Andreas H; Morris, David M; O'Connor, James P B; Robinson, Simon P; Van Beers, Bernard E; Waterton, John C

2015-12-01

To evaluate between-site agreement of apparent diffusion coefficient (ADC) measurements in preclinical magnetic resonance imaging (MRI) systems. A miniaturized thermally stable ice-water phantom was devised. ADC (mean and interquartile range) was measured over several days, on 4.7T, 7T, and 9.4T Bruker, Agilent, and Magnex small-animal MRI systems using a common protocol across seven sites. Day-to-day repeatability was expressed as percent variation of mean ADC between acquisitions. Cross-site reproducibility was expressed as 1.96 × standard deviation of percent deviation of ADC values. ADC measurements were equivalent across all seven sites with a cross-site ADC reproducibility of 6.3%. Mean day-to-day repeatability of ADC measurements was 2.3%, and no site was identified as presenting different measurements than others (analysis of variance [ANOVA] P = 0.02, post-hoc test n.s.). Between-slice ADC variability was negligible and similar between sites (P = 0.15). Mean within-region-of-interest ADC variability was 5.5%, with one site presenting a significantly greater variation than the others (P = 0.0013). Absolute ADC values in preclinical studies are comparable between sites and equipment, provided standardized protocols are employed. © 2015 Wiley Periodicals, Inc.

Wallerian Degeneration Beyond the Corticospinal Tracts: Conventional and Advanced MRI Findings.

PubMed

Chen, Yin Jie; Nabavizadeh, Seyed Ali; Vossough, Arastoo; Kumar, Sunil; Loevner, Laurie A; Mohan, Suyash

2017-05-01

Wallerian degeneration (WD) is defined as progressive anterograde disintegration of axons and accompanying demyelination after an injury to the proximal axon or cell body. Since the 1980s and 1990s, conventional magnetic resonance imaging (MRI) sequences have been shown to be sensitive to changes of WD in the subacute to chronic phases. More recently, advanced MRI techniques, such as diffusion-weighted imaging (DWI) and diffusion tensor imaging (DTI), have demonstrated some of earliest changes attributed to acute WD, typically on the order of days. In addition, there is increasing evidence on the value of advanced MRI techniques in providing important prognostic information related to WD. This article reviews the utility of conventional and advanced MRI techniques for assessing WD, by focusing not only on the corticospinal tract but also other neural tracts less commonly thought of, including corticopontocerebellar tract, dentate-rubro-olivary pathway, posterior column of the spinal cord, corpus callosum, limbic circuit, and optic pathway. The basic anatomy of these neural pathways will be discussed, followed by a comprehensive review of existing literature supported by instructive clinical examples. The goal of this review is for readers to become more familiar with both conventional and advanced MRI findings of WD involving important neural pathways, as well as to illustrate increasing utility of advanced MRI techniques in providing important prognostic information for various pathologies. Copyright © 2016 by the American Society of Neuroimaging.

Characterizing the microstructural basis of "unidentified bright objects" in neurofibromatosis type 1: A combined in vivo multicomponent T2 relaxation and multi-shell diffusion MRI analysis.

PubMed

Billiet, Thibo; Mädler, Burkhard; D'Arco, Felice; Peeters, Ronald; Deprez, Sabine; Plasschaert, Ellen; Leemans, Alexander; Zhang, Hui; den Bergh, Bea Van; Vandenbulcke, Mathieu; Legius, Eric; Sunaert, Stefan; Emsell, Louise

2014-01-01

The histopathological basis of "unidentified bright objects" (UBOs) (hyperintense regions seen on T2-weighted magnetic resonance (MR) brain scans in neurofibromatosis-1 (NF1)) remains unclear. New in vivo MRI-based techniques (multi-exponential T2 relaxation (MET2) and diffusion MR imaging (dMRI)) provide measures relating to microstructural change. We combined these methods and present previously unreported data on in vivo UBO microstructure in NF1. 3-Tesla dMRI data were acquired on 17 NF1 patients, covering 30 white matter UBOs. Diffusion tensor, kurtosis and neurite orientation and dispersion density imaging parameters were calculated within UBO sites and in contralateral normal appearing white matter (cNAWM). Analysis of MET2 parameters was performed on 24 UBO-cNAWM pairs. No significant alterations in the myelin water fraction and intra- and extracellular (IE) water fraction were found. Mean T2 time of IE water was significantly higher in UBOs. UBOs furthermore showed increased axial, radial and mean diffusivity, and decreased fractional anisotropy, mean kurtosis and neurite density index compared to cNAWM. Neurite orientation dispersion and isotropic fluid fraction were unaltered. Our results suggest that demyelination and axonal degeneration are unlikely to be present in UBOs, which appear to be mainly caused by a shift towards a higher T2-value of the intra- and extracellular water pool. This may arise from altered microstructural compartmentalization, and an increase in 'extracellular-like', intracellular water, possibly due to intramyelinic edema. These findings confirm the added value of combining dMRI and MET2 to characterize the microstructural basis of T2 hyperintensities in vivo.

CAIPIRINHA accelerated SPACE enables 10-min isotropic 3D TSE MRI of the ankle for optimized visualization of curved and oblique ligaments and tendons.

PubMed

Kalia, Vivek; Fritz, Benjamin; Johnson, Rory; Gilson, Wesley D; Raithel, Esther; Fritz, Jan

2017-09-01

To test the hypothesis that a fourfold CAIPIRINHA accelerated, 10-min, high-resolution, isotropic 3D TSE MRI prototype protocol of the ankle derives equal or better quality than a 20-min 2D TSE standard protocol. Following internal review board approval and informed consent, 3-Tesla MRI of the ankle was obtained in 24 asymptomatic subjects including 10-min 3D CAIPIRINHA SPACE TSE prototype and 20-min 2D TSE standard protocols. Outcome variables included image quality and visibility of anatomical structures using 5-point Likert scales. Non-parametric statistical testing was used. P values ≤0.001 were considered significant. Edge sharpness, contrast resolution, uniformity, noise, fat suppression and magic angle effects were without statistical difference on 2D and 3D TSE images (p > 0.035). Fluid was mildly brighter on intermediate-weighted 2D images (p < 0.001), whereas 3D images had substantially less partial volume, chemical shift and no pulsatile-flow artifacts (p < 0.001). Oblique and curved planar 3D images resulted in mildly-to-substantially improved visualization of joints, spring, bifurcate, syndesmotic, collateral and sinus tarsi ligaments, and tendons (p < 0.001, respectively). 3D TSE MRI with CAIPIRINHA acceleration enables high-spatial resolution oblique and curved planar MRI of the ankle and visualization of ligaments, tendons and joints equally well or better than a more time-consuming anisotropic 2D TSE MRI. • High-resolution 3D TSE MRI improves visualization of ankle structures. • Limitations of current 3D TSE MRI include long scan times. • 3D CAIPIRINHA SPACE allows now a fourfold-accelerated data acquisition. • 3D CAIPIRINHA SPACE enables high-spatial-resolution ankle MRI within 10 min. • 10-min 3D CAIPIRINHA SPACE produces equal-or-better quality than 20-min 2D TSE.

Trans-rectal interventional MRI: initial prostate biopsy experience

NASA Astrophysics Data System (ADS)

Greenwood, Bernadette M.; Behluli, Meliha R.; Feller, John F.; May, Stuart T.; Princenthal, Robert; Winkel, Alex; Kaminsky, David B.

2010-02-01

Dynamic contrast-enhanced (DCE) magnetic resonance imaging (MRI) of the prostate gland when evaluated along with T2-weighted images, diffusion-weighted images (DWI) and their corresponding apparent diffusion coefficient (ADC) maps can yield valuable information in patients with rising or elevated serum prostate-specific antigen (PSA) levels1. In some cases, patients present with multiple negative trans-rectal ultrasound (TRUS) biopsies, often placing the patient into a cycle of active surveillance. Recently, more patients are undergoing TRIM for targeted biopsy of suspicious findings with a cancer yield of ~59% compared to 15% for second TRUS biopsy2 to solve this diagnostic dilemma and plan treatment. Patients were imaged in two separate sessions on a 1.5T magnet using a cardiac phased array parallel imaging coil. Automated CAD software was used to identify areas of wash-out. If a suspicious finding was identified on all sequences it was followed by a second imaging session. Under MRI-guidance, cores were acquired from each target region3. In one case the microscopic diagnosis was prostatic intraepithelial neoplasia (PIN), in the other it was invasive adenocarcinoma. Patient 1 had two negative TRUS biopsies and a PSA level of 9ng/mL. Patient 2 had a PSA of 7.2ng/mL. He underwent TRUS biopsy which was negative for malignancy. He was able to go on to treatment for his prostate carcinoma (PCa)4. MRI may have an important role in a subset of patients with multiple negative TRUS biopsies and elevated or rising PSA.

Fusion of Computed Tomography and PROPELLER Diffusion-Weighted Magnetic Resonance Imaging for the Detection and Localization of Middle Ear Cholesteatoma.

PubMed

Locketz, Garrett D; Li, Peter M M C; Fischbein, Nancy J; Holdsworth, Samantha J; Blevins, Nikolas H

2016-10-01

A method to optimize imaging of cholesteatoma by combining the strengths of available modalities will improve diagnostic accuracy and help to target treatment. To assess whether fusing Periodically Rotated Overlapping Parallel Lines With Enhanced Reconstruction (PROPELLER) diffusion-weighted magnetic resonance imaging (DW-MRI) with corresponding temporal bone computed tomography (CT) images could increase cholesteatoma diagnostic and localization accuracy across 6 distinct anatomical regions of the temporal bone. Case series and preliminary technology evaluation of adults with preoperative temporal bone CT and PROPELLER DW-MRI scans who underwent surgery for clinically suggested cholesteatoma at a tertiary academic hospital. When cholesteatoma was encountered surgically, the precise location was recorded in a diagram of the middle ear and mastoid. For each patient, the 3 image data sets (CT, PROPELLER DW-MRI, and CT-MRI fusion) were reviewed in random order for the presence or absence of cholesteatoma by an investigator blinded to operative findings. If cholesteatoma was deemed present on review of each imaging modality, the location of the lesion was mapped presumptively. Image analysis was then compared with surgical findings. Twelve adults (5 women and 7 men; median [range] age, 45.5 [19-77] years) were included. The use of CT-MRI fusion had greater diagnostic sensitivity (0.88 vs 0.75), positive predictive value (0.88 vs 0.86), and negative predictive value (0.75 vs 0.60) than PROPELLER DW-MRI alone. Image fusion also showed increased overall localization accuracy when stratified across 6 distinct anatomical regions of the temporal bone (localization sensitivity and specificity, 0.76 and 0.98 for CT-MRI fusion vs 0.58 and 0.98 for PROPELLER DW-MRI). For PROPELLER DW-MRI, there were 15 true-positive, 45 true-negative, 1 false-positive, and 11 false-negative results; overall accuracy was 0.83. For CT-MRI fusion, there were 20 true-positive, 45 true-negative, 1 false-positive, and 6 false-negative results; overall accuracy was 0.90. The poor anatomical spatial resolution of DW-MRI makes precise localization of cholesteatoma within the middle ear and mastoid a diagnostic challenge. This study suggests that the bony anatomic detail obtained via CT coupled with the excellent sensitivity and specificity of PROPELLER DW-MRI for cholesteatoma can improve both preoperative identification and localization of disease over DW-MRI alone.

Acoustic-noise-optimized diffusion-weighted imaging.

PubMed

Ott, Martin; Blaimer, Martin; Grodzki, David M; Breuer, Felix A; Roesch, Julie; Dörfler, Arnd; Heismann, Björn; Jakob, Peter M

2015-12-01

This work was aimed at reducing acoustic noise in diffusion-weighted MR imaging (DWI) that might reach acoustic noise levels of over 100 dB(A) in clinical practice. A diffusion-weighted readout-segmented echo-planar imaging (EPI) sequence was optimized for acoustic noise by utilizing small readout segment widths to obtain low gradient slew rates and amplitudes instead of faster k-space coverage. In addition, all other gradients were optimized for low slew rates. Volunteer and patient imaging experiments were conducted to demonstrate the feasibility of the method. Acoustic noise measurements were performed and analyzed for four different DWI measurement protocols at 1.5T and 3T. An acoustic noise reduction of up to 20 dB(A) was achieved, which corresponds to a fourfold reduction in acoustic perception. The image quality was preserved at the level of a standard single-shot (ss)-EPI sequence, with a 27-54% increase in scan time. The diffusion-weighted imaging technique proposed in this study allowed a substantial reduction in the level of acoustic noise compared to standard single-shot diffusion-weighted EPI. This is expected to afford considerably more patient comfort, but a larger study would be necessary to fully characterize the subjective changes in patient experience.

3-D residual eddy current field characterisation: applied to diffusion weighted magnetic resonance imaging.

PubMed

O'Brien, Kieran; Daducci, Alessandro; Kickler, Nils; Lazeyras, Francois; Gruetter, Rolf; Feiweier, Thorsten; Krueger, Gunnar

2013-08-01

Clinical use of the Stejskal-Tanner diffusion weighted images is hampered by the geometric distortions that result from the large residual 3-D eddy current field induced. In this work, we aimed to predict, using linear response theory, the residual 3-D eddy current field required for geometric distortion correction based on phantom eddy current field measurements. The predicted 3-D eddy current field induced by the diffusion-weighting gradients was able to reduce the root mean square error of the residual eddy current field to ~1 Hz. The model's performance was tested on diffusion weighted images of four normal volunteers, following distortion correction, the quality of the Stejskal-Tanner diffusion-weighted images was found to have comparable quality to image registration based corrections (FSL) at low b-values. Unlike registration techniques the correction was not hindered by low SNR at high b-values, and results in improved image quality relative to FSL. Characterization of the 3-D eddy current field with linear response theory enables the prediction of the 3-D eddy current field required to correct eddy current induced geometric distortions for a wide range of clinical and high b-value protocols.

The Human Connectome Project: A data acquisition perspective

PubMed Central

Van Essen, D.C.; Ugurbil, K.; Auerbach, E.; Barch, D.; Behrens, T.E.J.; Bucholz, R.; Chang, A.; Chen, L.; Corbetta, M.; Curtiss, S.W.; Della Penna, S.; Feinberg, D.; Glasser, M.F.; Harel, N.; Heath, A.C.; Larson-Prior, L.; Marcus, D.; Michalareas, G.; Moeller, S.; Oostenveld, R.; Petersen, S.E.; Prior, F.; Schlaggar, B.L.; Smith, S.M.; Snyder, A.Z.; Xu, J.; Yacoub, E.

2012-01-01

The Human Connectome Project (HCP) is an ambitious 5-year effort to characterize brain connectivity and function and their variability in healthy adults. This review summarizes the data acquisition plans being implemented by a consortium of HCP investigators who will study a population of 1200 subjects (twins and their non-twin siblings) using multiple imaging modalities along with extensive behavioral and genetic data. The imaging modalities will include diffusion imaging (dMRI), resting-state fMRI (R-fMRI), task-evoked fMRI (T-fMRI), T1- and T2-weighted MRI for structural and myelin mapping, plus combined magnetoencephalography and electroencephalography (MEG/EEG). Given the importance of obtaining the best possible data quality, we discuss the efforts underway during the first two years of the grant (Phase I) to refine and optimize many aspects of HCP data acquisition, including a new 7T scanner, a customized 3T scanner, and improved MR pulse sequences. PMID:22366334

MRI in local staging of rectal cancer: an update

PubMed Central

Tapan, Ümit; Özbayrak, Mustafa; Tatlı, Servet

2014-01-01

Preoperative imaging for staging of rectal cancer has become an important aspect of current approach to rectal cancer management, because it helps to select suitable patients for neoadjuvant chemoradiotherapy and determine the appropriate surgical technique. Imaging modalities such as endoscopic ultrasonography, computed tomography, and magnetic resonance imaging (MRI) play an important role in assessing the depth of tumor penetration, lymph node involvement, mesorectal fascia and anal sphincter invasion, and presence of distant metastatic diseases. Currently, there is no consensus on a preferred imaging technique for preoperative staging of rectal cancer. However, high-resolution phased-array MRI is recommended as a standard imaging modality for preoperative local staging of rectal cancer, with excellent soft tissue contrast, multiplanar capability, and absence of ionizing radiation. This review will mainly focus on the role of MRI in preoperative local staging of rectal cancer and discuss recent advancements in MRI technique such as diffusion-weighted imaging and dynamic contrast-enhanced MRI. PMID:25010367

Evaluation of non-Gaussian diffusion in cardiac MRI.

PubMed

McClymont, Darryl; Teh, Irvin; Carruth, Eric; Omens, Jeffrey; McCulloch, Andrew; Whittington, Hannah J; Kohl, Peter; Grau, Vicente; Schneider, Jürgen E

2017-09-01

The diffusion tensor model assumes Gaussian diffusion and is widely applied in cardiac diffusion MRI. However, diffusion in biological tissue deviates from a Gaussian profile as a result of hindrance and restriction from cell and tissue microstructure, and may be quantified better by non-Gaussian modeling. The aim of this study was to investigate non-Gaussian diffusion in healthy and hypertrophic hearts. Thirteen rat hearts (five healthy, four sham, four hypertrophic) were imaged ex vivo. Diffusion-weighted images were acquired at b-values up to 10,000 s/mm 2 . Models of diffusion were fit to the data and ranked based on the Akaike information criterion. The diffusion tensor was ranked best at b-values up to 2000 s/mm 2 but reflected the signal poorly in the high b-value regime, in which the best model was a non-Gaussian "beta distribution" model. Although there was considerable overlap in apparent diffusivities between the healthy, sham, and hypertrophic hearts, diffusion kurtosis and skewness in the hypertrophic hearts were more than 20% higher in the sheetlet and sheetlet-normal directions. Non-Gaussian diffusion models have a higher sensitivity for the detection of hypertrophy compared with the Gaussian model. In particular, diffusion kurtosis may serve as a useful biomarker for characterization of disease and remodeling in the heart. Magn Reson Med 78:1174-1186, 2017. © 2016 International Society for Magnetic Resonance in Medicine. © 2016 The Authors Magnetic Resonance in Medicine published by Wiley Periodicals, Inc. on behalf of International Society for Magnetic Resonance in Medicine.

Diffusion, Perfusion, and Histopathologic Characteristics of Desmoplastic Infantile Ganglioglioma.

PubMed

Ho, Chang Y; Gener, Melissa; Bonnin, Jose; Kralik, Stephen F

2016-07-01

We present a case series of a rare tumor, the desmoplastic infantile ganglioglioma (DIG) with MRI diffusion and perfusion imaging quantification as well as histopathologic characterization. Four cases with pathologically-proven DIG had diffusion weighted imaging (DWI) and two of the four had dynamic susceptibility contrast imaging. All four tumors demonstrate DWI findings compatible with low-grade pediatric tumors. For the two cases with perfusion imaging, a higher relative cerebral blood volume was associated with higher proliferation index on histopathology for one of the cases. Our results are discussed in conjunction with a literature review.

Diffusion, Perfusion, and Histopathologic Characteristics of Desmoplastic Infantile Ganglioglioma

PubMed Central

Ho, Chang Y; Gener, Melissa; Bonnin, Jose; Kralik, Stephen F

2016-01-01

We present a case series of a rare tumor, the desmoplastic infantile ganglioglioma (DIG) with MRI diffusion and perfusion imaging quantification as well as histopathologic characterization. Four cases with pathologically-proven DIG had diffusion weighted imaging (DWI) and two of the four had dynamic susceptibility contrast imaging. All four tumors demonstrate DWI findings compatible with low-grade pediatric tumors. For the two cases with perfusion imaging, a higher relative cerebral blood volume was associated with higher proliferation index on histopathology for one of the cases. Our results are discussed in conjunction with a literature review. PMID:27761184

Assessment of the Focal Hepatic Lesions Using Diffusion Tensor Magnetic Resonance Imaging

PubMed Central

Oussous, Siham Ait; Boujraf, Saïd; Kamaoui, Imane

2016-01-01

The goal is assessing the diffusion magnetic resonance imaging (dMRI) method efficiency in characterizing focal hepatic lesions (FHLs). About 28-FHL patients were studied in Radiology and Clinical Imaging Department of our University Hospital using 1.5 Tesla MRI system between January 2010 and June 2011. Patients underwent hepatic MRI consisting of dynamic T1- and T2-weighted imaging. The dMRI was performed with b-values of 200 s/mm2 and 600 s/mm2. About 42 lesions measuring more than 1 cm were studied including the variation of the signal according to the b-value and the apparent diffusion coefficient (ADC). The diagnostic imaging reference was based on standard MRI techniques data for typical lesions and on histology after surgical biopsy for atypical lesions. About 38 lesions were assessed including 13 benign lesions consisting of 1 focal nodular hyperplasia, 8 angiomas, and 4 cysts. About 25 malignant lesions included 11 hepatocellular carcinoma, 9 hepatic metastases, 1 cholangiocarcinoma, and 4 lymphomas. dMRI of soft lesions demonstrated higher ADC of 2.26 ± 0.75 mm2/s, whereas solid lesions showed lower ADC 1.19 ± 0.33 mm2/s with significant difference (P = 0.05). Discrete values collections were noticed. These results were correlated to standard MRI and histological findings. Sensitivity of 93% and specificity of 84% were found in diagnoses of malignant tumors with an ADC threshold of 1.6 × 10−3 mm2/s. dMRI is important characterization method of FHL. However, it should not be used as single criteria of hepatic lesions malignity. MRI, clinical, and biological data must be correlated. Significant difference was found between benign and solid malignant lesions without threshold ADC values. Hence, it is difficult to confirm ADC threshold differentiating the lesion classification. PMID:27186537

Diffusion MRI with Semi-Automated Segmentation Can Serve as a Restricted Predictive Biomarker of the Therapeutic Response of Liver Metastasis

PubMed Central

Stephen, Renu M.; Jha, Abhinav K.; Roe, Denise J.; Trouard, Theodore P.; Galons, Jean-Philippe; Kupinski, Matthew A.; Frey, Georgette; Cui, Haiyan; Squire, Scott; Pagel, Mark D.; Rodriguez, Jeffrey J.; Gillies, Robert J.; Stopeck, Alison T.

2015-01-01

Purpose To assess the value of semi-automated segmentation applied to diffusion MRI for predicting the therapeutic response of liver metastasis. Methods Conventional diffusion weighted magnetic resonance imaging (MRI) was performed using b-values of 0, 150, 300 and 450 s/mm2 at baseline and days 4, 11 and 39 following initiation of a new chemotherapy regimen in a pilot study with 18 women with 37 liver metastases from primary breast cancer. A semi-automated segmentation approach was used to identify liver metastases. Linear regression analysis was used to assess the relationship between baseline values of the apparent diffusion coefficient (ADC) and change in tumor size by day 39. Results A semi-automated segmentation scheme was critical for obtaining the most reliable ADC measurements. A statistically significant relationship between baseline ADC values and change in tumor size at day 39 was observed for minimally treated patients with metastatic liver lesions measuring 2–5 cm in size (p = 0.002), but not for heavily treated patients with the same tumor size range (p = 0.29), or for tumors of smaller or larger sizes. ROC analysis identified a baseline threshold ADC value of 1.33 μm2/ms as 75% sensitive and 83% specific for identifying non-responding metastases in minimally treated patients with 2–5 cm liver lesions. Conclusion Quantitative imaging can substantially benefit from a semi-automated segmentation scheme. Quantitative diffusion MRI results can be predictive of therapeutic outcome in selected patients with liver metastases, but not for all liver metastases, and therefore should be considered to be a restricted biomarker. PMID:26284600

Diffusion MRI with Semi-Automated Segmentation Can Serve as a Restricted Predictive Biomarker of the Therapeutic Response of Liver Metastasis.

PubMed

Stephen, Renu M; Jha, Abhinav K; Roe, Denise J; Trouard, Theodore P; Galons, Jean-Philippe; Kupinski, Matthew A; Frey, Georgette; Cui, Haiyan; Squire, Scott; Pagel, Mark D; Rodriguez, Jeffrey J; Gillies, Robert J; Stopeck, Alison T

2015-12-01

To assess the value of semi-automated segmentation applied to diffusion MRI for predicting the therapeutic response of liver metastasis. Conventional diffusion weighted magnetic resonance imaging (MRI) was performed using b-values of 0, 150, 300 and 450s/mm(2) at baseline and days 4, 11 and 39 following initiation of a new chemotherapy regimen in a pilot study with 18 women with 37 liver metastases from primary breast cancer. A semi-automated segmentation approach was used to identify liver metastases. Linear regression analysis was used to assess the relationship between baseline values of the apparent diffusion coefficient (ADC) and change in tumor size by day 39. A semi-automated segmentation scheme was critical for obtaining the most reliable ADC measurements. A statistically significant relationship between baseline ADC values and change in tumor size at day 39 was observed for minimally treated patients with metastatic liver lesions measuring 2-5cm in size (p=0.002), but not for heavily treated patients with the same tumor size range (p=0.29), or for tumors of smaller or larger sizes. ROC analysis identified a baseline threshold ADC value of 1.33μm(2)/ms as 75% sensitive and 83% specific for identifying non-responding metastases in minimally treated patients with 2-5cm liver lesions. Quantitative imaging can substantially benefit from a semi-automated segmentation scheme. Quantitative diffusion MRI results can be predictive of therapeutic outcome in selected patients with liver metastases, but not for all liver metastases, and therefore should be considered to be a restricted biomarker. Copyright © 2015 Elsevier Inc. All rights reserved.

Assessment of cerebral venous sinus thrombosis using T2*-weighted gradient echo magnetic resonance imaging sequences

PubMed Central

Bidar, Fatemeh; Faeghi, Fariborz; Ghorbani, Askar

2016-01-01

Background: The purpose of this study is to demonstrate the advantages of gradient echo (GRE) sequences in the detection and characterization of cerebral venous sinus thrombosis compared to conventional magnetic resonance sequences. Methods: A total of 17 patients with cerebral venous thrombosis (CVT) were evaluated using different magnetic resonance imaging (MRI) sequences. The MRI sequences included T1-weighted spin echo (SE) imaging, T*2-weighted turbo SE (TSE), fluid attenuated inversion recovery (FLAIR), T*2-weighted conventional GRE, and diffusion weighted imaging (DWI). MR venography (MRV) images were obtained as the golden standard. Results: Venous sinus thrombosis was best detectable in T*2-weighted conventional GRE sequences in all patients except in one case. Venous thrombosis was undetectable in DWI. T*2-weighted GRE sequences were superior to T*2-weighted TSE, T1-weighted SE, and FLAIR. Enhanced MRV was successful in displaying the location of thrombosis. Conclusion: T*2-weighted conventional GRE sequences are probably the best method for the assessment of cerebral venous sinus thrombosis. The mentioned method is non-invasive; therefore, it can be employed in the clinical evaluation of cerebral venous sinus thrombosis. PMID:27326365

White Matter Connectivity of the Thalamus Delineates the Functional Architecture of Competing Thalamocortical Systems

PubMed Central

O'Muircheartaigh, Jonathan; Keller, Simon S.; Barker, Gareth J.; Richardson, Mark P.

2015-01-01

There is an increasing awareness of the involvement of thalamic connectivity on higher level cortical functioning in the human brain. This is reflected by the influence of thalamic stimulation on cortical activity and behavior as well as apparently cortical lesion syndromes occurring as a function of small thalamic insults. Here, we attempt to noninvasively test the correspondence of structural and functional connectivity of the human thalamus using diffusion-weighted and resting-state functional MRI. Using a large sample of 102 adults, we apply tensor independent component analysis to diffusion MRI tractography data to blindly parcellate bilateral thalamus according to diffusion tractography-defined structural connectivity. Using resting-state functional MRI collected in the same subjects, we show that the resulting structurally defined thalamic regions map to spatially distinct, and anatomically predictable, whole-brain functional networks in the same subjects. Although there was significant variability in the functional connectivity patterns, the resulting 51 structural and functional patterns could broadly be reduced to a subset of 7 similar core network types. These networks were distinct from typical cortical resting-state networks. Importantly, these networks were distributed across the brain and, in a subset, map extremely well to known thalamocortico-basal-ganglial loops. PMID:25899706

Sparse Bayesian Inference of White Matter Fiber Orientations from Compressed Multi-resolution Diffusion MRI

PubMed Central

Pisharady, Pramod Kumar; Duarte-Carvajalino, Julio M; Sotiropoulos, Stamatios N; Sapiro, Guillermo; Lenglet, Christophe

2017-01-01

The RubiX [1] algorithm combines high SNR characteristics of low resolution data with high spacial specificity of high resolution data, to extract microstructural tissue parameters from diffusion MRI. In this paper we focus on estimating crossing fiber orientations and introduce sparsity to the RubiX algorithm, making it suitable for reconstruction from compressed (under-sampled) data. We propose a sparse Bayesian algorithm for estimation of fiber orientations and volume fractions from compressed diffusion MRI. The data at high resolution is modeled using a parametric spherical deconvolution approach and represented using a dictionary created with the exponential decay components along different possible directions. Volume fractions of fibers along these orientations define the dictionary weights. The data at low resolution is modeled using a spatial partial volume representation. The proposed dictionary representation and sparsity priors consider the dependence between fiber orientations and the spatial redundancy in data representation. Our method exploits the sparsity of fiber orientations, therefore facilitating inference from under-sampled data. Experimental results show improved accuracy and decreased uncertainty in fiber orientation estimates. For under-sampled data, the proposed method is also shown to produce more robust estimates of fiber orientations. PMID:28845484

Sparse Bayesian Inference of White Matter Fiber Orientations from Compressed Multi-resolution Diffusion MRI.

PubMed

Pisharady, Pramod Kumar; Duarte-Carvajalino, Julio M; Sotiropoulos, Stamatios N; Sapiro, Guillermo; Lenglet, Christophe

2015-10-01

The RubiX [1] algorithm combines high SNR characteristics of low resolution data with high spacial specificity of high resolution data, to extract microstructural tissue parameters from diffusion MRI. In this paper we focus on estimating crossing fiber orientations and introduce sparsity to the RubiX algorithm, making it suitable for reconstruction from compressed (under-sampled) data. We propose a sparse Bayesian algorithm for estimation of fiber orientations and volume fractions from compressed diffusion MRI. The data at high resolution is modeled using a parametric spherical deconvolution approach and represented using a dictionary created with the exponential decay components along different possible directions. Volume fractions of fibers along these orientations define the dictionary weights. The data at low resolution is modeled using a spatial partial volume representation. The proposed dictionary representation and sparsity priors consider the dependence between fiber orientations and the spatial redundancy in data representation. Our method exploits the sparsity of fiber orientations, therefore facilitating inference from under-sampled data. Experimental results show improved accuracy and decreased uncertainty in fiber orientation estimates. For under-sampled data, the proposed method is also shown to produce more robust estimates of fiber orientations.

Registration of High Angular Resolution Diffusion MRI Images Using 4th Order Tensors⋆

PubMed Central

Barmpoutis, Angelos; Vemuri, Baba C.; Forder, John R.

2009-01-01

Registration of Diffusion Weighted (DW)-MRI datasets has been commonly achieved to date in literature by using either scalar or 2nd-order tensorial information. However, scalar or 2nd-order tensors fail to capture complex local tissue structures, such as fiber crossings, and therefore, datasets containing fiber-crossings cannot be registered accurately by using these techniques. In this paper we present a novel method for non-rigidly registering DW-MRI datasets that are represented by a field of 4th-order tensors. We use the Hellinger distance between the normalized 4th-order tensors represented as distributions, in order to achieve this registration. Hellinger distance is easy to compute, is scale and rotation invariant and hence allows for comparison of the true shape of distributions. Furthermore, we propose a novel 4th-order tensor re-transformation operator, which plays an essential role in the registration procedure and shows significantly better performance compared to the re-orientation operator used in literature for DTI registration. We validate and compare our technique with other existing scalar image and DTI registration methods using simulated diffusion MR data and real HARDI datasets. PMID:18051145

Physics, Techniques and Review of Neuroradiological Applications of Diffusion Kurtosis Imaging (DKI).

PubMed

Marrale, M; Collura, G; Brai, M; Toschi, N; Midiri, F; La Tona, G; Lo Casto, A; Gagliardo, C

2016-12-01

In recent years many papers about diagnostic applications of diffusion tensor imaging (DTI) have been published. This is because DTI allows to evaluate in vivo and in a non-invasive way the process of diffusion of water molecules in biological tissues. However, the simplified description of the diffusion process assumed in DTI does not permit to completely map the complex underlying cellular components and structures, which hinder and restrict the diffusion of water molecules. These limitations can be partially overcome by means of diffusion kurtosis imaging (DKI). The aim of this paper is the description of the theory of DKI, a new topic of growing interest in radiology. DKI is a higher order diffusion model that is a straightforward extension of the DTI model. Here, we analyze the physics underlying this method, we report our MRI acquisition protocol with the preprocessing pipeline used and the DKI parametric maps obtained on a 1.5 T scanner, and we review the most relevant clinical applications of this technique in various neurological diseases.

Combined 18F-Fluciclovine PET/MRI Shows Potential for Detection and Characterization of High-Risk Prostate Cancer.

PubMed

Elschot, Mattijs; Selnæs, Kirsten M; Sandsmark, Elise; Krüger-Stokke, Brage; Størkersen, Øystein; Giskeødegård, Guro F; Tessem, May-Britt; Moestue, Siver A; Bertilsson, Helena; Bathen, Tone F

2018-05-01

The objective of this study was to investigate whether quantitative imaging features derived from combined 18 F-fluciclovine PET/multiparametric MRI show potential for detection and characterization of primary prostate cancer. Methods: Twenty-eight patients diagnosed with high-risk prostate cancer underwent simultaneous 18 F-fluciclovine PET/MRI before radical prostatectomy. Volumes of interest (VOIs) for prostate tumors, benign prostatic hyperplasia (BPH) nodules, prostatitis, and healthy tissue were delineated on T2-weighted images, using histology as a reference. Tumor VOIs were marked as high-grade (≥Gleason grade group 3) or not. MRI and PET features were extracted on the voxel and VOI levels. Partial least-squared discriminant analysis (PLS-DA) with double leave-one-patient-out cross-validation was performed to distinguish tumors from benign tissue (BPH, prostatitis, or healthy tissue) and high-grade tumors from other tissue (low-grade tumors or benign tissue). The performance levels of PET, MRI, and combined PET/MRI features were compared using the area under the receiver-operating-characteristic curve (AUC). Results: Voxel and VOI features were extracted from 40 tumor VOIs (26 high-grade), 36 BPH VOIs, 6 prostatitis VOIs, and 37 healthy-tissue VOIs. PET/MRI performed better than MRI and PET alone for distinguishing tumors from benign tissue (AUCs of 87%, 81%, and 83%, respectively, at the voxel level and 96%, 93%, and 93%, respectively, at the VOI level) and high-grade tumors from other tissue (AUCs of 85%, 79%, and 81%, respectively, at the voxel level and 93%, 93%, and 91%, respectively, at the VOI level). T2-weighted MRI, diffusion-weighted MRI, and PET features were the most important for classification. Conclusion: Combined 18 F-fluciclovine PET/multiparametric MRI shows potential for improving detection and characterization of high-risk prostate cancer, in comparison to MRI and PET alone. © 2018 by the Society of Nuclear Medicine and Molecular Imaging.

Diffusion-Weighted PROPELLER MRI for Quantitative Assessment of Liver Tumor Necrotic Fraction and Viable Tumor Volume in VX2 Rabbits

PubMed Central

Deng, Jie; Virmani, Sumeet; Young, Joseph; Harris, Kathleen; Yang, Guang-Yu; Rademaker, Alfred; Woloschak, Gayle; Omary, Reed A.; Larson, Andrew C.

2010-01-01

Purpose To test the hypothesis that diffusion-weighted (DW)-PROPELLER (periodically rotated overlapping parallel lines with enhanced reconstruction) MRI provides more accurate liver tumor necrotic fraction (NF) and viable tumor volume (VTV) measurements than conventional DW-SE-EPI (spin echo echo-planar imaging) methods. Materials and Methods Our institutional Animal Care and Use Committee approved all experiments. In six rabbits implanted with 10 VX2 liver tumors, DW-PROPELLER and DW-SE-EPI scans were performed at contiguous axial slice positions covering each tumor volume. Apparent diffusion coefficient maps of each tumor were used to generate spatially resolved tumor viability maps for NF and VTV measurements. We compared NF, whole tumor volume (WTV), and VTV measurements to corresponding reference standard histological measurements based on correlation and concordance coefficients and the Bland–Altman analysis. Results DW-PROPELLER generally improved image quality with less distortion compared to DW-SE-EPI. DW-PROPELLER NF, WTV, and VTV measurements were strongly correlated and satisfactorily concordant with histological measurements. DW-SE-EPI NF measurements were weakly correlated and poorly concordant with histological measurements. Bland–Altman analysis demonstrated that DWPROPELLER WTV and VTV measurements were less biased from histological measurements than the corresponding DW-SE-EPI measurements. Conclusion DW-PROPELLER MRI can provide spatially resolved liver tumor viability maps for accurate NF and VTV measurements, superior to DW-SE-EPI approaches. DWPROPELLER measurements may serve as a noninvasive surrogate for pathology, offering the potential for more accurate assessments of therapy response than conventional anatomic size measurements. PMID:18407540

In-plane "superresolution" MRI with phaseless sub-pixel encoding.

PubMed

Hennel, Franciszek; Tian, Rui; Engel, Maria; Pruessmann, Klaas P

2018-04-15

Acquisition of high-resolution imaging data using multiple excitations without the sensitivity to fluctuations of the transverse magnetization phase, which is a major problem of multi-shot MRI. The concept of superresolution MRI based on microscopic tagging is analyzed using an analogy with the optical method of structured illumination. Sinusoidal tagging is shown to provide subpixel resolution by mixing of neighboring spatial frequency (k-space) bands. It represents a phaseless modulation added on top of the standard Fourier encoding, which allows the phase fluctuations to be discarded at an intermediate reconstruction step. Improvements are proposed to correct for tag distortions due to magnetic field inhomogeneity and to avoid the propagation of Gibbs ringing from intermediate low-resolution images to the final image. The method was applied to diffusion-weighted EPI. Artifact-free superresolution images can be obtained despite a finite duration of the tagging sequence and related pattern distortions by a field map based phase correction of band-wise reconstructed images. The ringing effect present in the intermediate images can be suppressed by partial overlapping of the mixed k-space bands in combination with an adapted filter. High-resolution diffusion-weighted images of the human head were obtained with a three-shot EPI sequence despite motion-related phase fluctuations between the shots. Due to its phaseless character, tagging-based sub-pixel encoding is an alternative to k-space segmenting in the presence of unknown phase fluctuations, in particular those due to motion under strong diffusion gradients. Proposed improvements render the method practicable in realistic conditions. © 2018 International Society for Magnetic Resonance in Medicine.

A Cost Analysis of a Pancreatic Cancer Screening Protocol in High-Risk Populations

PubMed Central

Bruenderman, Elizabeth; Martin, Robert CG

2016-01-01

Background Pancreatic cancer is the 4th leading cause of cancer death in the U.S. A screening protocol is needed to catch early stage, resectable disease. This study suggests a protocol for high-risk individuals and assesses the cost in the context of the Affordable Care Act. Methods Medicare and national average pricing were used for cost analysis of a protocol using MRI/MRCP biannually in high-risk groups. Results: ‘ Costs per year of life added’ based on Medicare and national average costs, respectively, are: $638.62 and $2542.37 for Peutz-Jehgers Syndrome, $945.33 and $3763.44 for Hereditary Pancreatitis, $1141.77 and $4545.45 for Familial Pancreatic Cancer and p16-Leiden mutations, and $356.42 and $1418.92 for new-onset diabetes over age 50 with weight loss or smoking. Conclusion A screening program using MRI/MRCP is affordable in high-risk populations. The U.S. Preventive Services Task Force must reevaluate its pancreatic cancer screening guidelines to make screening more cost-effective for the individual. PMID:26003200

Role of susceptibility-weighted imaging in demonstration of cerebral fat embolism

PubMed Central

Yeap, Pheyming; Kanodia, Avinash Kumar; Main, Gavin; Yong, Aiwain

2015-01-01

Cerebral fat embolism (CFE) is a rare but potentially lethal complication of long bone fractures. Many cases of CFE occur as subclinical events and remain undiagnosed. We report a case of a 22-year-old man, with multiple long bone fractures from a road traffic accident, who subsequently developed hypoxia, neurological abnormality and petechial rash. CT of the head was normal. MRI of the head confirmed the diagnosis with lesions markedly conspicuous and most widespread on susceptibility-weighted imaging as compared to all other sequences including diffusion-weighted imaging. PMID:25572601

Evaluation of dual-source parallel RF excitation for diffusion-weighted whole-body MR imaging with background body signal suppression at 3.0 T.

PubMed

Mürtz, Petra; Kaschner, Marius; Träber, Frank; Kukuk, Guido M; Büdenbender, Sarah M; Skowasch, Dirk; Gieseke, Jürgen; Schild, Hans H; Willinek, Winfried A

2012-11-01

To evaluate the use of dual-source parallel RF excitation (TX) for diffusion-weighted whole-body MRI with background body signal suppression (DWIBS) at 3.0 T. Forty consecutive patients were examined on a clinical 3.0-T MRI system using a diffusion-weighted (DW) spin-echo echo-planar imaging sequence with a combination of short TI inversion recovery and slice-selective gradient reversal fat suppression. DWIBS of the neck (n=5), thorax (n=8), abdomen (n=6) and pelvis (n=21) was performed both with TX (2:56 min) and with standard single-source RF excitation (4:37 min). The quality of DW images and reconstructed inverted maximum intensity projections was visually judged by two readers (blinded to acquisition technique). Signal homogeneity and fat suppression were scored as "improved", "equal", "worse" or "ambiguous". Moreover, the apparent diffusion coefficient (ADC) values were measured in muscles, urinary bladder, lymph nodes and lesions. By the use of TX, signal homogeneity was "improved" in 25/40 and "equal" in 15/40 cases. Fat suppression was "improved" in 17/40 and "equal" in 23/40 cases. These improvements were statistically significant (p<0.001, Wilcoxon signed-rank test). In five patients, fluid-related dielectric shading was present, which improved remarkably. The ADC values did not significantly differ for the two RF excitation methods (p=0.630 over all data, pairwise Student's t-test). Dual-source parallel RF excitation improved image quality of DWIBS at 3.0 T with respect to signal homogeneity and fat suppression, reduced scan time by approximately one-third, and did not influence the measured ADC values. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Increasing the Accuracy of Volume and ADC Delineation for Heterogeneous Tumor on Diffusion-Weighted MRI: Correlation with PET/CT

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

Gong, Nan-Jie; Wong, Chun-Sing, E-mail: drcswong@gmail.com; Chu, Yiu-Ching

2013-10-01

Purpose: To improve the accuracy of volume and apparent diffusion coefficient (ADC) measurements in diffusion-weighted magnetic resonance imaging (MRI), we proposed a method based on thresholding both the b0 images and the ADC maps. Methods and Materials: In 21 heterogeneous lesions from patients with metastatic gastrointestinal stromal tumors (GIST), gross lesion were manually contoured, and corresponding volumes and ADCs were denoted as gross tumor volume (GTV) and gross ADC (ADC{sub g}), respectively. Using a k-means clustering algorithm, the probable high-cellularity tumor tissues were selected based on b0 images and ADC maps. ADC and volume of the tissues selected using themore » proposed method were denoted as thresholded ADC (ADC{sub thr}) and high-cellularity tumor volume (HCTV), respectively. The metabolic tumor volume (MTV) in positron emission tomography (PET)/computed tomography (CT) was measured using 40% maximum standard uptake value (SUV{sub max}) as the lower threshold, and corresponding mean SUV (SUV{sub mean}) was also measured. Results: HCTV had excellent concordance with MTV according to Pearson's correlation (r=0.984, P<.001) and linear regression (slope = 1.085, intercept = −4.731). In contrast, GTV overestimated the volume and differed significantly from MTV (P=.005). ADC{sub thr} correlated significantly and strongly with SUV{sub mean} (r=−0.807, P<.001) and SUV{sub max} (r=−0.843, P<.001); both were stronger than those of ADC{sub g}. Conclusions: The proposed lesion-adaptive semiautomatic method can help segment high-cellularity tissues that match hypermetabolic tissues in PET/CT and enables more accurate volume and ADC delineation on diffusion-weighted MR images of GIST.« less

Voxelwise multivariate analysis of multimodality magnetic resonance imaging

PubMed Central

Naylor, Melissa G.; Cardenas, Valerie A.; Tosun, Duygu; Schuff, Norbert; Weiner, Michael; Schwartzman, Armin

2015-01-01

Most brain magnetic resonance imaging (MRI) studies concentrate on a single MRI contrast or modality, frequently structural MRI. By performing an integrated analysis of several modalities, such as structural, perfusion-weighted, and diffusion-weighted MRI, new insights may be attained to better understand the underlying processes of brain diseases. We compare two voxelwise approaches: (1) fitting multiple univariate models, one for each outcome and then adjusting for multiple comparisons among the outcomes and (2) fitting a multivariate model. In both cases, adjustment for multiple comparisons is performed over all voxels jointly to account for the search over the brain. The multivariate model is able to account for the multiple comparisons over outcomes without assuming independence because the covariance structure between modalities is estimated. Simulations show that the multivariate approach is more powerful when the outcomes are correlated and, even when the outcomes are independent, the multivariate approach is just as powerful or more powerful when at least two outcomes are dependent on predictors in the model. However, multiple univariate regressions with Bonferroni correction remains a desirable alternative in some circumstances. To illustrate the power of each approach, we analyze a case control study of Alzheimer's disease, in which data from three MRI modalities are available. PMID:23408378

Intrahepatic and hilar mass-forming cholangiocarcinoma: Qualitative and quantitative evaluation with diffusion-weighted MR imaging.

PubMed

Fattach, Hassan El; Dohan, Anthony; Guerrache, Youcef; Dautry, Raphael; Boudiaf, Mourad; Hoeffel, Christine; Soyer, Philippe

2015-08-01

To qualitatively and quantitatively analyze the presentation of intrahepatic and hilar mass-forming cholangiocarcinoma with diffusion-weighted magnetic resonance imaging (DW-MRI). Twenty-eight patients with histopathologically proven mass-forming cholangiocarcinoma (hilar, n=17; intrahepatic, n=11) underwent hepatic DW-MRI at 1.5-T using free-breathing acquisition and three b-values (0,400,800s/mm(2)). Cholangiocarcinomas were evaluated qualitatively using visual analysis of DW-MR images and quantitatively with conventional ADC and normalized ADC measurements using liver and spleen as reference organs. All cholangiocarcinomas (28/28; 100%) were visible on DW-MR images. DW-MRI yielded best conspicuity of cholangiocarcinomas than the other MRI sequences (P<0.001). Seven cholangiocarcinomas (7/11; 64%) showed hypointense central area on DW-MR images. Conventional ADC value of cholangiocarcinomas (1.042×10(-3)mm(2)/s±0.221×10(-3)mm(2)/s; range: 0.616×10(-3)mm(2)/s to 2.050×10(-3)mm(2)/s) was significantly lower than that of apparently normal hepatic parenchyma (1.362×10(-3)mm(2)/s±0.187×10(-3)mm(2)/s) (P<0.0001), although substantial overlap was found. No significant differences in ADC and normalized ADC values were found between intrahepatic and hilar cholangiocarcinomas. The use of normalized ADC using the liver as reference organ resulted in the most restricted distribution of ADC values of cholangiocarcinomas (variation coefficient=16.6%). There is a trend towards a common appearance of intrahepatic and hilar mass-forming cholangiocarcinomas on DW-MRI but variations may be observed. Familiarity with these variations may improve the diagnosis of mass-forming cholangiocarcinoma. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

HINTS to diagnose stroke in the acute vestibular syndrome: three-step bedside oculomotor examination more sensitive than early MRI diffusion-weighted imaging.

PubMed

Kattah, Jorge C; Talkad, Arun V; Wang, David Z; Hsieh, Yu-Hsiang; Newman-Toker, David E

2009-11-01

Acute vestibular syndrome (AVS) is often due to vestibular neuritis but can result from vertebrobasilar strokes. Misdiagnosis of posterior fossa infarcts in emergency care settings is frequent. Bedside oculomotor findings may reliably identify stroke in AVS, but prospective studies have been lacking. The authors conducted a prospective, cross-sectional study at an academic hospital. Consecutive patients with AVS (vertigo, nystagmus, nausea/vomiting, head-motion intolerance, unsteady gait) with >or=1 stroke risk factor underwent structured examination, including horizontal head impulse test of vestibulo-ocular reflex function, observation of nystagmus in different gaze positions, and prism cross-cover test of ocular alignment. All underwent neuroimaging and admission (generally <72 hours after symptom onset). Strokes were diagnosed by MRI or CT. Peripheral lesions were diagnosed by normal MRI and clinical follow-up. One hundred one high-risk patients with AVS included 25 peripheral and 76 central lesions (69 ischemic strokes, 4 hemorrhages, 3 other). The presence of normal horizontal head impulse test, direction-changing nystagmus in eccentric gaze, or skew deviation (vertical ocular misalignment) was 100% sensitive and 96% specific for stroke. Skew was present in 17% and associated with brainstem lesions (4% peripheral, 4% pure cerebellar, 30% brainstem involvement; chi(2), P=0.003). Skew correctly predicted lateral pontine stroke in 2 of 3 cases in which an abnormal horizontal head impulse test erroneously suggested peripheral localization. Initial MRI diffusion-weighted imaging was falsely negative in 12% (all <48 hours after symptom onset). Skew predicts brainstem involvement in AVS and can identify stroke when an abnormal horizontal head impulse test falsely suggests a peripheral lesion. A 3-step bedside oculomotor examination (HINTS: Head-Impulse-Nystagmus-Test-of-Skew) appears more sensitive for stroke than early MRI in AVS.

Retrospective analysis of the utility of multiparametric MRI for differentiating between benign and malignant breast lesions in women in China

PubMed Central

Fan, Wei Xiong; Chen, Xiao Feng; Cheng, Feng Yan; Cheng, Ya Bao; Xu, Tai; Zhu, Wen Biao; Zhu, Xiao Lei; Li, Gui Jin; Li, Shuai

2018-01-01

Abstract We explored the utility of time-resolved angiography with interleaved stochastic trajectories dynamic contrast-enhanced magnetic resonance imaging (TWIST DCE-MRI), readout segmentation of long variable echo-trains diffusion-weighted magnetic resonance imaging- diffusion-weighted magnetic resonance imaging (RESOLVE-DWI), and echo-planar imaging- diffusion-weighted magnetic resonance imaging (EPI-DWI) for distinguishing between malignant and benign breast lesions. This retrospective analysis included female patients with breast lesions seen at a single center in China between January 2016 and April 2016. Patients were allocated to a benign or malignant group based on pathologic diagnosis. All patients received routine MRI, RESOLVE-DWI, EPI-DWI, and TWIST DCE-T1WI. Variables measured included quantitative parameters (Ktrans, Kep, and Ve), semiquantitative parameters (rate of contrast enhancement for contrast agent inflow [W-in], rate of contrast decay for contrast agent outflow [W-out], and time-to-peak enhancement after contrast agent injection [TTP]) and apparent diffusion coefficient (ADC) values for RESOLVE-DWI (ADCr) and EPI-DWI (ADCe). Receiver-operating characteristic (ROC) curve analysis was used to evaluate the diagnostic utility of each parameter for differentiating malignant from benign breast lesions. A total of 87 patients were included (benign, n = 20; malignant, n = 67). Compared with the benign group, the malignant group had significantly higher Ktrans, Kep and W-in and significantly lower W-out, TTP, ADCe, and ADCr (all P < .05); Ve was not significantly different between groups. RESOLVE-DWI was superior to conventional EPI-DWI at illustrating lesion boundary and morphology, while ADCr was significantly lower than ADCe in all patients. Kep, W-out, ADCr, and ADCe showed the highest diagnostic efficiency (based on AUC value) for differentiating between benign and malignant lesions. Combining 3 parameters (Kep, W-out, and ADCr) had a higher diagnostic efficiency (AUC, 0.965) than any individual parameter and distinguished between benign and malignant lesions with high sensitivity (91.0%), specificity (95.0%), and accuracy (91.9%). An index combining Kep, W-out, and ADCr could potentially be used for the differential diagnosis of breast lesions. PMID:29369183

Retrospective analysis of the utility of multiparametric MRI for differentiating between benign and malignant breast lesions in women in China.

PubMed

Fan, Wei Xiong; Chen, Xiao Feng; Cheng, Feng Yan; Cheng, Ya Bao; Xu, Tai; Zhu, Wen Biao; Zhu, Xiao Lei; Li, Gui Jin; Li, Shuai

2018-01-01

We explored the utility of time-resolved angiography with interleaved stochastic trajectories dynamic contrast-enhanced magnetic resonance imaging (TWIST DCE-MRI), readout segmentation of long variable echo-trains diffusion-weighted magnetic resonance imaging- diffusion-weighted magnetic resonance imaging (RESOLVE-DWI), and echo-planar imaging- diffusion-weighted magnetic resonance imaging (EPI-DWI) for distinguishing between malignant and benign breast lesions.This retrospective analysis included female patients with breast lesions seen at a single center in China between January 2016 and April 2016. Patients were allocated to a benign or malignant group based on pathologic diagnosis. All patients received routine MRI, RESOLVE-DWI, EPI-DWI, and TWIST DCE-T1WI. Variables measured included quantitative parameters (K, Kep, and Ve), semiquantitative parameters (rate of contrast enhancement for contrast agent inflow [W-in], rate of contrast decay for contrast agent outflow [W-out], and time-to-peak enhancement after contrast agent injection [TTP]) and apparent diffusion coefficient (ADC) values for RESOLVE-DWI (ADCr) and EPI-DWI (ADCe). Receiver-operating characteristic (ROC) curve analysis was used to evaluate the diagnostic utility of each parameter for differentiating malignant from benign breast lesions.A total of 87 patients were included (benign, n = 20; malignant, n = 67). Compared with the benign group, the malignant group had significantly higher K, Kep and W-in and significantly lower W-out, TTP, ADCe, and ADCr (all P < .05); Ve was not significantly different between groups. RESOLVE-DWI was superior to conventional EPI-DWI at illustrating lesion boundary and morphology, while ADCr was significantly lower than ADCe in all patients. Kep, W-out, ADCr, and ADCe showed the highest diagnostic efficiency (based on AUC value) for differentiating between benign and malignant lesions. Combining 3 parameters (Kep, W-out, and ADCr) had a higher diagnostic efficiency (AUC, 0.965) than any individual parameter and distinguished between benign and malignant lesions with high sensitivity (91.0%), specificity (95.0%), and accuracy (91.9%).An index combining Kep, W-out, and ADCr could potentially be used for the differential diagnosis of breast lesions.

Monitoring of the tumor response to nano-graphene oxide-mediated photothermal/photodynamic therapy by diffusion-weighted and BOLD MRI

NASA Astrophysics Data System (ADS)

Cao, Jianbo; An, Hengqing; Huang, Xinglu; Fu, Guifeng; Zhuang, Rongqiang; Zhu, Lei; Xie, Jin; Zhang, Fan

2016-05-01

Photothermal therapy (PTT) and photodynamic therapy (PDT) are promising cancer treatment modalities. Because each modality has its own set of advantages and limitations, there has been interest in developing methods that can co-deliver the two regimens for enhanced tumor treatment. Among the efforts, nano-graphene oxide-mediated phototherapies have recently attracted much attention. Nano-graphene oxide has a broad absorbance spectrum and can be loaded with photosensitizers, such as chlorin e6, with high efficiency. Chlorin e6-loaded and PEGylated nano-graphene (GO-PEG-Ce6) can be excited at 660 nm, 808 nm, or both, to induce PDT, PTT, or PDT/PTT combination. Despite the potential of the treatments, there is a lack of a diagnostic tool which can monitor their therapeutic response in a non-invasive and prognostic manner; such an ability is urgently needed for the transformation and translation of the technologies. In this study, we performed diffusion-weighted and blood oxygenation level dependent (BOLD) magnetic resonance imaging (MRI) after GO-PEG-Ce6-mediated PTT, PDT, or PTT/PDT. We found that after efficient PTT, there is a significant increase of the tumor apparent diffusion coefficient (ADC) value in diffusion-weighted imaging (DWI) maps; meanwhile, an efficient PDT led to an increase of in BOLD images. In both the cases, the amplitude of the increase was correlated with the treatment outcomes. More interestingly, a synergistic treatment efficacy was observed when the PTT/PDT combination was applied, and the combination was associated with a greater ADC and increase than when either modality was used alone. In particular, the PTT/PDT condition that induced the most dramatic short-term increase of the ADC value (>70%) caused the most effective tumor control in the long-run, with 60% of the treated animals being tumor-free after 60 days. These results suggest the great promise of the combination of DWI and BOLD MRI as a tool for accurate monitoring and prognosis of phototherapies, which is of great value to the future developments of the methodologies.

Brain abscess mimicking lung cancer metastases; a case report.

PubMed

Asano, Michiko; Fujimoto, Nobukazu; Fuchimoto, Yasuko; Ono, Katsuichiro; Ozaki, Shinji; Kimura, Fumiaki; Kishimoto, Takumi

2013-01-01

A 76-year-old woman came to us because of staggering, fever, dysarthria, and appetite loss. Magnetic resonance imaging (MRI) of the brain revealed multiple masses with surrounding edema. Chest X-ray and computed tomography demonstrated a mass-like lesion in the left lung and left pleural effusion. Lung cancer and multiple brain metastases were suspected. However, the brain lesions demonstrated a high intensity through diffusion-weighted MRI. The finding was an important key to differentiate brain abscesses from lung cancer metastases. Copyright © 2013 Elsevier Inc. All rights reserved.

Accuracies and Contrasts of Models of the Diffusion-Weighted-Dependent Attenuation of the MRI Signal at Intermediate b-values.

PubMed

Nicolas, Renaud; Sibon, Igor; Hiba, Bassem

2015-01-01

The diffusion-weighted-dependent attenuation of the MRI signal E(b) is extremely sensitive to microstructural features. The aim of this study was to determine which mathematical model of the E(b) signal most accurately describes it in the brain. The models compared were the monoexponential model, the stretched exponential model, the truncated cumulant expansion (TCE) model, the biexponential model, and the triexponential model. Acquisition was performed with nine b-values up to 2500 s/mm(2) in 12 healthy volunteers. The goodness-of-fit was studied with F-tests and with the Akaike information criterion. Tissue contrasts were differentiated with a multiple comparison corrected nonparametric analysis of variance. F-test showed that the TCE model was better than the biexponential model in gray and white matter. Corrected Akaike information criterion showed that the TCE model has the best accuracy and produced the most reliable contrasts in white matter among all models studied. In conclusion, the TCE model was found to be the best model to infer the microstructural properties of brain tissue.

Ex post facto assessment of diffusion tensor imaging metrics from different MRI protocols: preparing for multicentre studies in ALS.

PubMed

Rosskopf, Johannes; Müller, Hans-Peter; Dreyhaupt, Jens; Gorges, Martin; Ludolph, Albert C; Kassubek, Jan

2015-03-01

Diffusion tensor imaging (DTI) for assessing ALS-associated white matter alterations has still not reached the level of a neuroimaging biomarker. Since large-scale multicentre DTI studies in ALS may be hampered by differences in scanning protocols, an approach for pooling of DTI data acquired with different protocols was investigated. Three hundred and nine datasets from 170 ALS patients and 139 controls were collected ex post facto from a monocentric database reflecting different scanning protocols. A 3D correction algorithm was introduced for a combined analysis of DTI metrics despite different acquisition protocols, with the focus on the CST as the tract correlate of ALS neuropathological stage 1. A homogenous set of data was obtained by application of 3D correction matrices. Results showed that a fractional anisotropy (FA) threshold of 0.41 could be defined to discriminate ALS patients from controls (sensitivity/specificity, 74%/72%). For the remaining test sample, sensitivity/specificity values of 68%/74% were obtained. In conclusion, the objective was to merge data recorded with different DTI protocols with 3D correction matrices for analyses at group level. These post processing tools might facilitate analysis of large study samples in a multicentre setting for DTI analysis at group level to aid in establishing DTI as a non-invasive biomarker for ALS.

Understanding the effects of diffusion and relaxation in magnetic resonance imaging using computational modeling

NASA Astrophysics Data System (ADS)

Russell, Greg

The work described in this dissertation was motivated by a desire to better understand the cellular pathology of ischemic stroke. Two of the three bodies of research presented herein address and issue directly related to the investigation of ischemic stroke through the use of diffusion weighted magnetic resonance imaging (DWMRI) methods. The first topic concerns the development of a computationally efficient finite difference method, designed to evaluate the impact of microscopic tissue properties on the formation of DWMRI signal. For the second body of work, the effect of changing the intrinsic diffusion coefficient of a restricted sample on clinical DWMRI experiments is explored. The final body of work, while motivated by the desire to understand stroke, addresses the issue of acquiring large amounts of MRI data well suited for quantitative analysis in reduced scan time. In theory, the method could be used to generate quantitative parametric maps, including those depicting information gleaned through the use of DWMRI methods. Chapter 1 provides an introduction to several topics. A description of the use of DWMRI methods in the study of ischemic stroke is covered. An introduction to the fundamental physical principles at work in MRI is also provided. In this section the means by which magnetization is created in MRI experiments, how MRI signal is induced, as well as the influence of spin-spin and spin-lattice relaxation are discussed. Attention is also given to describing how MRI measurements can be sensitized to diffusion through the use of qualitative and quantitative descriptions of the process. Finally, the reader is given a brief introduction to the use of numerical methods for solving partial differential equations. In Chapters 2, 3 and 4, three related bodies of research are presented in terms of research papers. In Chapter 2, a novel computational method is described. The method reduces the computation resources required to simulate DWMRI experiments. In Chapter 3, a detailed study on how changes in the intrinsic intracellular diffusion coefficient may influence clinical DWMRI experiments is described. In Chapter 4, a novel, non-steady state quantitative MRI method is described.

The emerging potential of magnetic resonance imaging in personalizing radiotherapy for head and neck cancer: an oncologist's perspective.

PubMed

Wong, Kee H; Panek, Rafal; Bhide, Shreerang A; Nutting, Christopher M; Harrington, Kevin J; Newbold, Katie L

2017-03-01

Head and neck cancer (HNC) is a challenging tumour site for radiotherapy delivery owing to its complex anatomy and proximity to organs at risk (OARs) such as the spinal cord and optic apparatus. Despite significant advances in radiotherapy planning techniques, radiation-induced morbidities remain substantial. Further improvement would require high-quality imaging and tailored radiotherapy based on intratreatment response. For these reasons, the use of MRI in radiotherapy planning for HNC is rapidly gaining popularity. MRI provides superior soft-tissue contrast in comparison with CT, allowing better definition of the tumour and OARs. The lack of additional radiation exposure is another attractive feature for intratreatment monitoring. In addition, advanced MRI techniques such as diffusion-weighted, dynamic contrast-enhanced and intrinsic susceptibility-weighted MRI techniques are capable of characterizing tumour biology further by providing quantitative functional parameters such as tissue cellularity, vascular permeability/perfusion and hypoxia. These functional parameters are known to have radiobiological relevance, which potentially could guide treatment adaptation based on their changes prior to or during radiotherapy. In this article, we first present an overview of the applications of anatomical MRI sequences in head and neck radiotherapy, followed by the potentials and limitations of functional MRI sequences in personalizing therapy.

The emerging potential of magnetic resonance imaging in personalizing radiotherapy for head and neck cancer: an oncologist's perspective

PubMed Central

Panek, Rafal; Bhide, Shreerang A; Nutting, Christopher M; Harrington, Kevin J; Newbold, Katie L

2017-01-01

Head and neck cancer (HNC) is a challenging tumour site for radiotherapy delivery owing to its complex anatomy and proximity to organs at risk (OARs) such as the spinal cord and optic apparatus. Despite significant advances in radiotherapy planning techniques, radiation-induced morbidities remain substantial. Further improvement would require high-quality imaging and tailored radiotherapy based on intratreatment response. For these reasons, the use of MRI in radiotherapy planning for HNC is rapidly gaining popularity. MRI provides superior soft-tissue contrast in comparison with CT, allowing better definition of the tumour and OARs. The lack of additional radiation exposure is another attractive feature for intratreatment monitoring. In addition, advanced MRI techniques such as diffusion-weighted, dynamic contrast-enhanced and intrinsic susceptibility-weighted MRI techniques are capable of characterizing tumour biology further by providing quantitative functional parameters such as tissue cellularity, vascular permeability/perfusion and hypoxia. These functional parameters are known to have radiobiological relevance, which potentially could guide treatment adaptation based on their changes prior to or during radiotherapy. In this article, we first present an overview of the applications of anatomical MRI sequences in head and neck radiotherapy, followed by the potentials and limitations of functional MRI sequences in personalizing therapy. PMID:28256151

[The possibilities for diagnostics of prescription of death coming based on the changes in the lumbar intervertebral disks (the comparison of the morphological, immunohistochemical and topographical findings)].

PubMed

Byval'tsev, V A; Stepanov, I A; Semenov, A V; Perfil'ev, D V; Belykh, E G; Bardonova, L A; Nikiforov, S B; Sudakov, N P; Bespyatykh, I V; Antipina, S L

The objective of the present study was the comprehensive analysis of the postmortem changes in the lumbar intervertebral disks within different periods after death. A total of seven vertebromotor segments were distinguished in the lumbosacral region of the vertebral column based on the examination of 7 corpses. All these segments were divided into three groups in accordance with the prescription of death coming as follows: up to 12 hours (group 1), between 12 and 24 hours (group 2), and between 24 and 36 hours (group 3) after death. The models of the segments thus obtained were subjected to the study by means of diffusion weighted MRI. The removed intervertebral disks were used for morphological and immunohistochemical investigations. The comparison of the diffusion coefficients (DI) revealed the significant difference between the intervertebral disks assigned to groups 1 and 2 (p<0.01). The number of the cells in the pulpal core, the vertebral end plate, and the fibrous ring in all the above groups of the intervertebral disks was significantly reduced (p<0.01). The analysis of the correlation dependence between cell density and diffusion coefficients has demonstrated the well apparent relationship between these characteristics of the intervertebral disks comprising groups 1 and 2. It is concluded that diffusion weighted MRI in the combination with the calculation of diffusion coefficients for the intervertebral disks provides a tool for diagnostics of prescription of death coming as confirmed by the results of the morphometric studies and immunohistochemical analysis.

Incorporating drug delivery into an imaging-driven, mechanics-coupled reaction diffusion model for predicting the response of breast cancer to neoadjuvant chemotherapy: theory and preliminary clinical results

NASA Astrophysics Data System (ADS)

Jarrett, Angela M.; Hormuth, David A.; Barnes, Stephanie L.; Feng, Xinzeng; Huang, Wei; Yankeelov, Thomas E.

2018-05-01

Clinical methods for assessing tumor response to therapy are largely rudimentary, monitoring only temporal changes in tumor size. Our goal is to predict the response of breast tumors to therapy using a mathematical model that utilizes magnetic resonance imaging (MRI) data obtained non-invasively from individual patients. We extended a previously established, mechanically coupled, reaction-diffusion model for predicting tumor response initialized with patient-specific diffusion weighted MRI (DW-MRI) data by including the effects of chemotherapy drug delivery, which is estimated using dynamic contrast-enhanced (DCE-) MRI data. The extended, drug incorporated, model is initialized using patient-specific DW-MRI and DCE-MRI data. Data sets from five breast cancer patients were used—obtained before, after one cycle, and at mid-point of neoadjuvant chemotherapy. The DCE-MRI data was used to estimate spatiotemporal variations in tumor perfusion with the extended Kety–Tofts model. The physiological parameters derived from DCE-MRI were used to model changes in delivery of therapy drugs within the tumor for incorporation in the extended model. We simulated the original model and the extended model in both 2D and 3D and compare the results for this five-patient cohort. Preliminary results show reductions in the error of model predicted tumor cellularity and size compared to the experimentally-measured results for the third MRI scan when therapy was incorporated. Comparing the two models for agreement between the predicted total cellularity and the calculated total cellularity (from the DW-MRI data) reveals an increased concordance correlation coefficient from 0.81 to 0.98 for the 2D analysis and 0.85 to 0.99 for the 3D analysis (p  <  0.01 for each) when the extended model was used in place of the original model. This study demonstrates the plausibility of using DCE-MRI data as a means to estimate drug delivery on a patient-specific basis in predictive models and represents a step toward the goal of achieving individualized prediction of tumor response to therapy.

Multi-Parametric Spinal Cord MRI as Potential Progression Marker in Amyotrophic Lateral Sclerosis

PubMed Central

El Mendili, Mohamed-Mounir; Cohen-Adad, Julien; Pelegrini-Issac, Mélanie; Rossignol, Serge; Morizot-Koutlidis, Régine; Marchand-Pauvert, Véronique; Iglesias, Caroline; Sangari, Sina; Katz, Rose; Lehericy, Stéphane; Benali, Habib; Pradat, Pierre-François

2014-01-01

Objective To evaluate multimodal MRI of the spinal cord in predicting disease progression and one-year clinical status in amyotrophic lateral sclerosis (ALS) patients. Materials and Methods After a first MRI (MRI1), 29 ALS patients were clinically followed during 12 months; 14/29 patients underwent a second MRI (MRI2) at 11±3 months. Cross-sectional area (CSA) that has been shown to be a marker of lower motor neuron degeneration was measured in cervical and upper thoracic spinal cord from T2-weighted images. Fractional anisotropy (FA), axial/radial/mean diffusivities (λ⊥, λ//, MD) and magnetization transfer ratio (MTR) were measured within the lateral corticospinal tract in the cervical region. Imaging metrics were compared with clinical scales: Revised ALS Functional Rating Scale (ALSFRS-R) and manual muscle testing (MMT) score. Results At MRI1, CSA correlated significantly (P<0.05) with MMT and arm ALSFRS-R scores. FA correlated significantly with leg ALFSRS-R scores. One year after MRI1, CSA predicted (P<0.01) arm ALSFSR-R subscore and FA predicted (P<0.01) leg ALSFRS-R subscore. From MRI1 to MRI2, significant changes (P<0.01) were detected for CSA and MTR. CSA rate of change (i.e. atrophy) highly correlated (P<0.01) with arm ALSFRS-R and arm MMT subscores rate of change. Conclusion Atrophy and DTI metrics predicted ALS disease progression. Cord atrophy was a better biomarker of disease progression than diffusion and MTR. Our study suggests that multimodal MRI could provide surrogate markers of ALS that may help monitoring the effect of disease-modifying drugs. PMID:24755826

WE-G-BRD-01: Diffusion Weighted MRI for Response Assessment of Inoperable Lung Tumors for Patients Undergoing SBRT Treatment

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

Tyagi, N; Wengler, K; Yorke, E

2014-06-15

Purpose: To investigate early changes in tumor Apparent Diffusion Coefficients derived from diffusion weighted (DW)-MRI of lung cancer patients undergoing SBRT, as a possible early predictor of treatment response. Methods: DW-MRI scans were performed in this prospective phase I IRB-approved study of inoperable lung tumors at various time-points during the course of SBRT treatments. Axial DW scan using multi b-values ranging from 0–1000 s/mm{sup 2} were acquired in treatment position on a 3T Philips MR scanner during simulation, one hour after the first fraction (8 Gy), after a total of 5 fractions (40 Gy) and 4 weeks after SBRT delivery.more » A monoexponential model based on a least square fit from all b values was performed on a pixel-by-pixel basis and ADC was calculated. GTVs drawn on 4DCT for planning were mapped on the T2w MRI (acquired at exhale) after deformable registration. These volumes were then mapped on DWI scan for ADC calculation after rigid registration between the anatomical scan and diffusion scan. T2w scan on followup time points were deformably registered to the pretreatment T2 scan. Results: The first two patients in this study were analyzed. Median ADC values were 1.48, 1.48, 1.62 and 1.83 (10{sup −3}×) mm{sup 2}/s at pretreatment, after 8 Gy, after 40 Gy and 4 weeks posttreatment for the first patient and 1.57, 1.53, 1.66 and 1.72 (10{sup −3}×) mm{sup 2}/s for the second patient. ADC increased more significantly after 4 weeks of treatment rather than immediately post treatment, implying that late ADC value may be a better predictor of tumor response for SBRT treatment. The fraction of tumor pixels at high ADC values increased at 4 weeks post treatment. Conclusion: The observed increase in ADC values before the end of radiotherapy may be a surrogate for tumor response, but further patient accrual will be necessary to determine its value.« less

Simple Fabrication of Gd(III)-DTPA-Nanodiamond Particles by Chemical Modification for Use as Magnetic Resonance Imaging (MRI) Contrast Agent

NASA Astrophysics Data System (ADS)

Nakamura, Takako; Ohana, Tsuguyori; Yabuno, Hajime; Kasai, Rumiko; Suzuki, Tetsuya; Hasebe, Terumitsu

2013-01-01

We have developed a simple and useful process for fabricating nanodiamond (ND) particles modified with an organogadolinium moiety by chemical modification for their use as a magnetic resonance imaging (MRI) contrast agent. The introduction of the organogadolinium moiety on the surface of the ND particles was performed by the condensation of ND and diethylenetriaminepentaacetic acid (DTPA) followed by treatment with GdCl3. The modified surfaces were evaluated by X-ray photoelectron spectroscopy, diffuse reflectance Fourier transform infrared spectroscopy, mass spectroscopy, and inductively coupled plasma atomic emission spectroscopy analyses. MRI experiments on the Gd-DTPA-ND particles indicated their high signal intensity on T1-weighted images.

Improve definition of titanium tandems in MR-guided high dose rate brachytherapy for cervical cancer using proton density weighted MRI

PubMed Central

2013-01-01

Background For cervical cancer patients treated with MR-guided high dose rate brachytherapy, the accuracy of radiation delivery depends on accurate localization of both tumors and the applicator, e.g. tandem and ovoid. Standard T2-weighted (T2W) MRI has good tumor-tissue contrast. However, it suffers from poor uterus-tandem contrast, which makes the tandem delineation very challenging. In this study, we evaluated the possibility of using proton density weighted (PDW) MRI to improve the definition of titanium tandems. Methods Both T2W and PDW MRI images were obtained from each cervical cancer patient. Imaging parameters were kept the same between the T2W and PDW sequences for each patient except the echo time (90 ms for T2W and 5.5 ms for PDW) and the slice thickness (0.5 cm for T2W and 0.25 cm for PDW). Uterus-tandem contrast was calculated by the equation C = (Su-St)/Su, where Su and St represented the average signal in the uterus and the tandem, respectively. The diameter of the tandem was measured 1.5 cm away from the tip of the tandem. The tandem was segmented by the histogram thresholding technique. Results PDW MRI could significantly improve the uterus-tandem contrast compared to T2W MRI (0.42±0.24 for T2W MRI, 0.77±0.14 for PDW MRI, p=0.0002). The average difference between the measured and physical diameters of the tandem was reduced from 0.20±0.15 cm by using T2W MRI to 0.10±0.11 cm by using PDW MRI (p=0.0003). The tandem segmented from the PDW image looked more uniform and complete compared to that from the T2W image. Conclusions Compared to the standard T2W MRI, PDW MRI has better uterus-tandem contrast. The information provided by PDW MRI is complementary to those provided by T2W MRI. Therefore, we recommend adding PDW MRI to the simulation protocol to assist tandem delineation process for cervical cancer patients. PMID:23327682

[A case of MM1+2 Creutzfeldt-Jakob disease with a longitudinal study of EEG and MRI].

PubMed

Katsube, Mizuho; Shiota, Yuri; Harada, Takayuki; Shibata, Hiroshi; Nagai, Atsushi

2013-11-01

We report a case of definite MM1 + 2 sporadic Creutzfeldt-Jakob disease (sCJD). A 66-year-old woman was admitted to our hospital with memory disturbance and disorientation for three months. On admission she presented a progressive cognitive insufficiency. Electroencephalography (EEG) revealed a frontal intermittent rhythmical delta activity (FIRDA) and the brain magnetic resonance imaging (MRI) showed high signal intensities in cerebral cortex on diffusion weighted images (DWI). After four months from the onset, she reached the akinetic mutism state followed by myoclonus. Follow up examination revealed that periodic synchronous discharge (PSD) was found in EEG, and DWI revealed enlargement of high signal intensity lesions in cerebral cortex. At seven months from the onset, PSD and high signal intensities of cortex became unclear with disappearance of myoclonus, and brain white matter lesions were evident on MRI. Serial studies of EEG and MRI revealed that PSD generalized from frontal lobe dominant pattern, while high signal intensity lesions of cortex diffusely increased on DWI. At ten months from the onset patient died. Pathological examination in brain showed moderate and diffuse neuronal cell loss and gliosis in cerebral cortex corresponding with DWI changes. The genotype at codon 129 of the prion protein (PrP) was homozygous methionine (MM) and the type of protease-resistant PrP (PrPres) was the mixed type of 1 and 2 in Western blot analysis. It has been rare to analyze the changes of EEG and MRI in the entire stage and to investigate pathological finding in the case of sCJD-MM1 + 2. A longitudinal examination of EEG and MRI is useful for early diagnosis of CJD. Also we could correlate these findings with clinical and histopathological phenotype.

MRI Evaluation and Safety in the Developing Brain

PubMed Central

Tocchio, Shannon; Kline-Fath, Beth; Kanal, Emanuel; Schmithorst, Vincent J.; Panigrahy, Ashok

2015-01-01

Magnetic resonance imaging (MRI) evaluation of the developing brain has dramatically increased over the last decade. Faster acquisitions and the development of advanced MRI sequences such as magnetic resonance spectroscopy (MRS), diffusion tensor imaging (DTI), perfusion imaging, functional MR imaging (fMRI), and susceptibility weighted imaging (SWI), as well as the use of higher magnetic field strengths has made MRI an invaluable tool for detailed evaluation of the developing brain. This article will provide an overview of the use and challenges associated with 1.5T and 3T static magnetic fields for evaluation of the developing brain. This review will also summarize the advantages, clinical challenges and safety concerns specifically related to MRI in the fetus and newborn, including the implications of increased magnetic field strength, logistics related to transporting and monitoring of neonates during scanning, sedation considerations and a discussion of current technologies such as MRI-conditional neonatal incubators and dedicated small-foot print neonatal intensive care unit (NICU) scanners. PMID:25743582

MRI evaluation and safety in the developing brain.

PubMed

Tocchio, Shannon; Kline-Fath, Beth; Kanal, Emanuel; Schmithorst, Vincent J; Panigrahy, Ashok

2015-03-01

Magnetic resonance imaging (MRI) evaluation of the developing brain has dramatically increased over the last decade. Faster acquisitions and the development of advanced MRI sequences, such as magnetic resonance spectroscopy (MRS), diffusion tensor imaging (DTI), perfusion imaging, functional MR imaging (fMRI), and susceptibility-weighted imaging (SWI), as well as the use of higher magnetic field strengths has made MRI an invaluable tool for detailed evaluation of the developing brain. This article will provide an overview of the use and challenges associated with 1.5-T and 3-T static magnetic fields for evaluation of the developing brain. This review will also summarize the advantages, clinical challenges, and safety concerns specifically related to MRI in the fetus and newborn, including the implications of increased magnetic field strength, logistics related to transporting and monitoring of neonates during scanning, and sedation considerations, and a discussion of current technologies such as MRI conditional neonatal incubators and dedicated small-foot print neonatal intensive care unit (NICU) scanners. Copyright © 2015 Elsevier Inc. All rights reserved.

Gossypiboma Mimicking Gastrointestinal Stromal Tumor Causing Intestinal Obstruction: A Case Report

PubMed Central

Kawamura, Yurika; Ogasawara, Naotaka; Yamamoto, Sayuri; Sasaki, Makoto; Kawamura, Naohiko; Izawa, Shinya; Kobayashi, Yuji; Kamei, Seiji; Miyachi, Masahiko; Kasugai, Kunio

2012-01-01

A 41-year-old woman was admitted to our hospital with abdominal pain that developed about 1 year after a Cesarean section. Pelvic computed tomography (CT) revealed diffuse dilation of the small intestine with fluid shadows and a pelvic tumor 55 mm in diameter. The density of the tumor, which was not enhanced by intravenous contrast medium, was diffuse and similar to that of muscular tissue, whereas the density of a capsule surrounding the mass was relatively high. T1- and T2-weighted pelvic magnetic resonance imaging (MRI) of the tumor revealed the same diffuse low-intensity signals as muscular tissue, and diffuse high-intensity signals, respectively. The CT and MRI findings were consistent with those of a gastrointestinal stromal tumor (GIST) causing ileus of the small intestine. As inserting an ileus tube did not improve her symptoms, the patient was scheduled for tumor resection. The operative findings revealed a hard, solid tumor adhering to the surrounding small intestine. The macroscopic findings revealed that the tumor consisted of layers of stratified gauze surrounded by a thick granulomatous wall. The gossypiboma was considered to have originated from gauze that had been left behind after the Cesarean section. If a patient has a history of surgery, the possibility of gossypiboma should be considered when CT or MRI findings indicate features of GIST. PMID:22679410

Value of diffusion-weighted MRI during carotid angioplasty and stenting.

PubMed

McDonnell, C O; Fearn, S J; Baker, S R; Goodman, M A; Price, D; Lawrence-Brown, M M D

2006-07-01

The incidence of neurological injury following carotid angioplasty and stenting is of great interest to those advocating it as an alternative to endarterectomy in the management of critical carotid stenosis. A significant inter-observer variation exists in determining the presence or absence of a neurological deficit following the procedure objective imaging would be advantageous. In this study, we sought to assess diffusion weighted MRI as a diagnostic tool in evaluating the incidence of neurological injury following carotid angioplasty and stenting (CAS). The first 110 cases of CAS in our unit were included in this series. The procedure was abandoned in three patients. Patients underwent intracranial and extracranial MR angiography, together with diffusion-weighted MRI (DWI) prior to and following CAS and had a formal neurological assessment in the intensive care unit after the procedure. One hundred and ten Procedures were attempted in 98 patients. Twenty-eight percent were asymptomatic. Following CAS, 7.2% of patients had a positive neurological exam (two major strokes with one fatality) and 21% had positive DWI scans, equating to a sensitivity of 86% and a specificity of 85% for DWI in detecting cerebral infarction following CAS. The positive predictive value of the test was 0.3 and negative predictive value 0.99. The major stroke and death rate was 1.8%. While the use of a cerebral protection device appeared to significantly reduce the incidence of cerebral infarction (5% vs. 25%, p = 0.031) this may be a reflection of the learning curve encountered during the study. The incidence of subclinical DWI detected neurological injury was significantly higher than clinical neurological deficit following CAS. Conventional methods of neurological assessment of patients undergoing CAS may be too crude to detect subtle changes and more sensitive tests of cerebral function are required to establish whether these subclinical lesions are relevant.

Quantitative diffusion MRI using reduced field-of-view and multi-shot acquisition techniques: Validation in phantoms and prostate imaging.

PubMed

Zhang, Yuxin; Holmes, James; Rabanillo, Iñaki; Guidon, Arnaud; Wells, Shane; Hernando, Diego

2018-09-01

To evaluate the reproducibility of quantitative diffusion measurements obtained with reduced Field of View (rFOV) and Multi-shot EPI (msEPI) acquisitions, using single-shot EPI (ssEPI) as a reference. Diffusion phantom experiments, and prostate diffusion-weighted imaging in healthy volunteers and patients with known or suspected prostate cancer were performed across the three different sequences. Quantitative diffusion measurements of apparent diffusion coefficient, and diffusion kurtosis parameters (healthy volunteers), were obtained and compared across diffusion sequences (rFOV, msEPI, and ssEPI). Other possible confounding factors like b-value combinations and acquisition parameters were also investigated. Both msEPI and rFOV have shown reproducible quantitative diffusion measurements relative to ssEPI; no significant difference in ADC was observed across pulse sequences in the standard diffusion phantom (p = 0.156), healthy volunteers (p ≥ 0.12) or patients (p ≥ 0.26). The ADC values within the non-cancerous central gland and peripheral zone of patients were 1.29 ± 0.17 × 10 -3  mm 2 /s and 1.74 ± 0.23 × 10 -3  mm 2 /s respectively. However, differences in quantitative diffusion parameters were observed across different number of averages for rFOV, and across b-value groups and diffusion models for all the three sequences. Both rFOV and msEPI have the potential to provide high image quality with reproducible quantitative diffusion measurements in prostate diffusion MRI. Copyright © 2018 Elsevier Inc. All rights reserved.

Diffusion-Weighted Magnetic Resonance Imaging Early After Chemoradiotherapy to Monitor Treatment Response in Head-and-Neck Squamous Cell Carcinoma

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

Vandecaveye, Vincent, E-mail: Vincent.Vandecaveye@uzleuven.be; Dirix, Piet; De Keyzer, Frederik

2012-03-01

Purpose: To evaluate diffusion-weighted imaging (DWI) for assessment of treatment response in head and neck squamous cell carcinoma (HNSCC) three weeks after the end of chemoradiotherapy (CRT). Methods and Materials: Twenty-nine patients with HNSCC underwent magnetic resonance imaging (MRI) prior to and 3 weeks after CRT, including T{sub 2}-weighted and pre- and postcontrast T{sub 1}-weighted sequences and an echo-planar DWI sequence with six b values (0 to 1,000 s/mm{sup 2}), from which the apparent diffusion coefficient (ADC) was calculated. ADC changes 3 weeks posttreatment compared to baseline ( Increment ADC) between responding and nonresponding primary lesions and adenopathies were correlatedmore » with 2 years locoregional control and compared with a Mann-Whitney test. In a blinded manner, the Increment ADC was compared to conventional MRI 3 weeks post-CRT and the routinely implemented CT, on average 3 months post-CRT, which used size-related and morphological criteria. Positive and negative predictive values (PPV and NPV, respectively) were compared between the Increment ADC and anatomical imaging. Results: The Increment ADC of lesions with later tumor recurrence was significantly lower than lesions with complete remission for both primary lesions (-2.3% {+-} 0.3% vs. 80% {+-} 41%; p < 0.0001) and adenopathies (19.9% {+-} 32% vs. 63% {+-} 36%; p = 0.003). The Increment ADC showed a PPV of 89% and an NPV of 100% for primary lesions and a PPV of 70% and an NPV of 96% for adenopathies per neck side. DWI improved PPV and NPV compared to anatomical imaging. Conclusion: DWI with the Increment ADC 3 weeks after concluding CRT for HNSCC allows for early assessment of treatment response.« less

Advantages of high b-value diffusion-weighted imaging to diagnose pseudo-responses in patients with recurrent glioma after bevacizumab treatment.

PubMed

Yamasaki, Fumiyuki; Kurisu, Kaoru; Aoki, Tomokazu; Yamanaka, Masami; Kajiwara, Yoshinori; Watanabe, Yosuke; Takayasu, Takeshi; Akiyama, Yuji; Sugiyama, Kazuhiko

2012-10-01

The diagnosis of pseudo-responses after bevacizumab treatment is difficult. Because diffusion-weighted imaging (DWI) is associated with cell density, it may facilitate the differentiation between true- and pseudo-responses. Furthermore, as high b-value DWI is even more sensitive to diffusion, it has been reported to be diagnostically useful in various clinical settings. Between September 2008 and May 2011, 10 patients (5 males, 5 females; age range 6-65 years) with recurrent glioma were treated with bevacizumab. All underwent pre- and post-treatment MRI including T2- or FLAIR imaging, post-gadolinium contrast T1-weighted imaging, and DWI with b-1000 and b-4000. Response rates were evaluated by MacDonald- and by response assessment in neuro-oncology working group (RANO) criteria. We also assessed the response rate by calculating the size of high intensity areas using high b-value diffusion-weighted criteria. Prognostic factors were evaluated using Kaplan-Meier survival curves (log-rank test). It was easier to identify pseudo-responses with RANO- than MacDonald criteria, however the reduction of edema by bevacizumab rendered the early diagnosis of tumor progression difficult by RANO criteria. In some patients with recurrent glioma treated with bevacizumab, high b-value diffusion-weighted criteria did, while MacDonald- and RANO criteria did not identify pseudo-responses at an early point after the start of therapy. High b-value DWI reflects cell density more accurately than regular b-value DWI. Our findings suggest that in patients with recurrent glioma, high b-value diffusion-weighted criteria are useful for the differentiation between pseudo- and true responses to treatment with bevacizumab. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

Toward Distinguishing Recurrent Tumor From Radiation Necrosis: DWI and MTC in a Gamma Knife–Irradiated Mouse Glioma Model

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

Perez-Torres, Carlos J.; Engelbach, John A.; Cates, Jeremy

Purpose: Accurate noninvasive diagnosis is vital for effective treatment planning. Presently, standard anatomical magnetic resonance imaging (MRI) is incapable of differentiating recurring tumor from delayed radiation injury, as both lesions are hyperintense in both postcontrast T1- and T2-weighted images. Further studies are therefore necessary to identify an MRI paradigm that can differentially diagnose these pathologies. Mouse glioma and radiation injury models provide a powerful platform for this purpose. Methods and Materials: Two MRI contrasts that are widely used in the clinic were chosen for application to a glioma/radiation-injury model: diffusion weighted imaging, from which the apparent diffusion coefficient (ADC) ismore » obtained, and magnetization transfer contrast, from which the magnetization transfer ratio (MTR) is obtained. These metrics were evaluated longitudinally, first in each lesion type alone–glioma versus irradiation – and then in a combined irradiated glioma model. Results: MTR was found to be consistently decreased in all lesions compared to nonlesion brain tissue (contralateral hemisphere), with limited specificity between lesion types. In contrast, ADC, though less sensitive to the presence of pathology, was increased in radiation injury and decreased in tumors. In the irradiated glioma model, ADC also increased immediately after irradiation, but decreased as the tumor regrew. Conclusions: ADC is a better metric than MTR for differentiating glioma from radiation injury. However, MTR was more sensitive to both tumor and radiation injury than ADC, suggesting a possible role in detecting lesions that do not enhance strongly on T1-weighted images.« less

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

PubMed

Barnett, Madeleine L; Tusor, Nora; Ball, Gareth; Chew, Andrew; Falconer, Shona; Aljabar, Paul; Kimpton, Jessica A; Kennea, Nigel; Rutherford, Mary; David Edwards, A; Counsell, Serena J

2018-01-01

Preterm infants are at high risk of diffuse white matter injury and adverse neurodevelopmental outcome. The multiple hit hypothesis suggests that the risk of white matter injury increases with cumulative exposure to multiple perinatal risk factors. Our aim was to test this hypothesis in a large cohort of preterm infants using diffusion weighted magnetic resonance imaging (dMRI). We studied 491 infants (52% male) without focal destructive brain lesions born at < 34 weeks, who underwent structural and dMRI at a specialist Neonatal Imaging Centre. The median (range) gestational age (GA) at birth was 30 + 1 (23 + 2 -33 + 5 ) weeks and median postmenstrual age at scan was 42 + 1 (38-45) weeks. dMRI data were analyzed using tract based spatial statistics and the relationship between dMRI measures in white matter and individual perinatal risk factors was assessed. We tested the hypothesis that increased exposure to perinatal risk factors was associated with lower fractional anisotropy (FA), and higher radial, axial and mean diffusivity (RD, AD, MD) in white matter. Neurodevelopmental performance was investigated using the Bayley Scales of Infant and Toddler Development, Third Edition (BSITD-III) in a subset of 381 infants at 20 months corrected age. We tested the hypothesis that lower FA and higher RD, AD and MD in white matter were associated with poorer neurodevelopmental performance. Identified risk factors for diffuse white matter injury were lower GA at birth, fetal growth restriction, increased number of days requiring ventilation and parenteral nutrition, necrotizing enterocolitis and male sex. Clinical chorioamnionitis and patent ductus arteriosus were not associated with white matter injury. Multivariate analysis demonstrated that fetal growth restriction, increased number of days requiring ventilation and parenteral nutrition were independently associated with lower FA values. Exposure to cumulative risk factors was associated with reduced white matter FA and FA values at term equivalent age were associated with subsequent neurodevelopmental performance. 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.

A rare case of short stature: Say Meyer syndrome.

PubMed

Karthik, T S; Prasad, N Rajendra; Rani, P Radha; Maheshwari, Rushikesh; Reddy, P Amaresh; Chakradhar, B V S; Menon, Bindu

2013-10-01

Say Meyer syndrome is rare X linked condition characterized by developmental delay, short stature and metopic suture synostosis. We are reporting a case of Say Meyer syndrome presented to our hospital for short stature and developmental delay at age 3½ years. A 3½-year-old boy presented to our hospital for decreased growth velocity from the age of 1 year. History revealed the boy had a birth weight of 2.3 kg, had an episode of seizures in the neonatal period. He was born to non-consanguineous marriage. He had global developmental delay and there was a lack of bowel and bladder control. History did not reveal any hearing or visual impairment. No history of any chronic systemic illnesses. Magnetic resonance imaging (MRI) brain revealed mild diffuse frontotemporal atrophy with multiple irregular gliotic areas in bilateral frontal lobes. Diffuse white matter volume loss in bilateral cerebral hemispheres. Diffuse thinning of corpus callosum. Diffuse periventricular hyper intensity on T2W and fluid attenuated inversion recovery sequences. Say Meyer syndrome is rare X linked condition characterized by developmental delay, short stature and metopic suture synostosis. Characteristic MRI brain findings include diffuse frontotemporal atrophy with multiple gliotic areas in frontal lobes. Diffuse white matter volume loss in bilateral cerebral hemispheres.

Multiple Echo Diffusion Tensor Acquisition Technique (MEDITATE) on a 3T clinical scanner

PubMed Central

Baete, Steven H.; Cho, Gene; Sigmund, Eric E.

2013-01-01

This paper describes the concepts and implementation of an MRI method, Multiple Echo Diffusion Tensor Acquisition Technique (MEDITATE), which is capable of acquiring apparent diffusion tensor maps in two scans on a 3T clinical scanner. In each MEDITATE scan, a set of RF-pulses generates multiple echoes whose amplitudes are diffusion-weighted in both magnitude and direction by a pattern of diffusion gradients. As a result, two scans acquired with different diffusion weighting strengths suffice for accurate estimation of diffusion tensor imaging (DTI)-parameters. The MEDITATE variation presented here expands previous MEDITATE approaches to adapt to the clinical scanner platform, such as exploiting longitudinal magnetization storage to reduce T2-weighting. Fully segmented multi-shot Cartesian encoding is used for image encoding. MEDITATE was tested on isotropic (agar gel), anisotropic diffusion phantoms (asparagus), and in vivo skeletal muscle in healthy volunteers with cardiac-gating. Comparisons of accuracy were performed with standard twice-refocused spin echo (TRSE) DTI in each case and good quantitative agreement was found between diffusion eigenvalues, mean diffusivity, and fractional anisotropy derived from TRSE-DTI and from the MEDITATE sequence. Orientation patterns were correctly reproduced in both isotropic and anisotropic phantoms, and approximately so for in vivo imaging. This illustrates that the MEDITATE method of compressed diffusion encoding is feasible on the clinical scanner platform. With future development and employment of appropriate view-sharing image encoding this technique may be used in clinical applications requiring time-sensitive acquisition of DTI parameters such as dynamical DTI in muscle. PMID:23828606

Multicontrast multiecho FLASH MRI for targeting the subthalamic nucleus.

PubMed

Xiao, Yiming; Beriault, Silvain; Pike, G Bruce; Collins, D Louis

2012-06-01

The subthalamic nucleus (STN) is one of the most common stimulation targets for treating Parkinson's disease using deep brain stimulation (DBS). This procedure requires precise placement of the stimulating electrode. Common practice of DBS implantation utilizes microelectrode recording to locate the sites with the correct electrical response after an initial location estimate based on a universal human brain atlas that is linearly scaled to the patient's anatomy as seen on the preoperative images. However, this often results in prolonged surgical time and possible surgical complications since the small-sized STN is difficult to visualize on conventional magnetic resonance (MR) images and its intersubject variability is not sufficiently considered in the atlas customization. This paper proposes a multicontrast, multiecho MR imaging (MRI) method that directly delineates the STN and other basal ganglia structures through five co-registered image contrasts (T1-weighted navigation image, R2 map, susceptibility-weighted imaging (phase, magnitude and fusion image)) obtained within a clinically acceptable time. The image protocol was optimized through both simulation and in vivo experiments to obtain the best image quality. Taking advantage of the multiple echoes and high readout bandwidths, no interimage registration is required since all images are produced in one acquisition, and image distortion and chemical shift are reduced. This MRI protocol is expected to mitigate some of the shortcomings of the state-of-the-art DBS implantation methods. Copyright © 2012 Elsevier Inc. All rights reserved.

Apparent diffusion coefficient as it relates to histopathology findings in post-chemotherapy nephroblastoma: a feasibility study.

PubMed

Littooij, Annemieke S; Nikkels, Peter G; Hulsbergen-van de Kaa, Christina A; van de Ven, Cees P; van den Heuvel-Eibrink, Marry M; Olsen, Øystein E

2017-11-01

Nephroblastomas represent a group of heterogeneous tumours with variable proportions of distinct histopathological components. The purpose of this study was to investigate whether direct comparison of apparent diffusion coefficient (ADC) measurements with post-resection histopathology subtypes is feasible and whether ADC metrics are related to histopathological components. Twenty-three children were eligible for inclusion in this retrospective study. All children had MRI including diffusion-weighted imaging (DWI) after preoperative chemotherapy, just before tumour resection. A pathologist and radiologist identified corresponding slices at MRI and postoperative specimens using tumour morphology, the upper/lower calyx and hilar vessels as reference points. An experienced reader performed ADC measurements, excluding non-enhancing areas. A pathologist reviewed the corresponding postoperative slides according to the international standard guidelines. We tested potential associations with the Spearman rank test. Side-by-side comparison of MRI-DWI with corresponding histopathology slides was feasible in 15 transverse slices in 9 lesions in 8 patients. Most exclusions were related to extensive areas of necrosis/haemorrhage. In one lesion correlation was not possible because of the different orientation of sectioning of the specimen and MRI slices. The 25% ADC showed a strong relationship with percentage of blastema (Spearman rho=-0.71, P=0.003), whereas median ADC was strongly related to the percentage stroma (Spearman rho=0.74, P=0.002) at histopathology. Side-by-side comparison of MRI-DWI and histopathology is feasible in the majority of patients who do not have massive necrosis and hemorrhage. Blastemal and stromal components have a strong linear relationship with ADC markers.

k-space and q-space: combining ultra-high spatial and angular resolution in diffusion imaging using ZOOPPA at 7 T.

PubMed

Heidemann, Robin M; Anwander, Alfred; Feiweier, Thorsten; Knösche, Thomas R; Turner, Robert

2012-04-02

There is ongoing debate whether using a higher spatial resolution (sampling k-space) or a higher angular resolution (sampling q-space angles) is the better way to improve diffusion MRI (dMRI) based tractography results in living humans. In both cases, the limiting factor is the signal-to-noise ratio (SNR), due to the restricted acquisition time. One possible way to increase the spatial resolution without sacrificing either SNR or angular resolution is to move to a higher magnetic field strength. Nevertheless, dMRI has not been the preferred application for ultra-high field strength (7 T). This is because single-shot echo-planar imaging (EPI) has been the method of choice for human in vivo dMRI. EPI faces several challenges related to the use of a high resolution at high field strength, for example, distortions and image blurring. These problems can easily compromise the expected SNR gain with field strength. In the current study, we introduce an adapted EPI sequence in conjunction with a combination of ZOOmed imaging and Partially Parallel Acquisition (ZOOPPA). We demonstrate that the method can produce high quality diffusion-weighted images with high spatial and angular resolution at 7 T. We provide examples of in vivo human dMRI with isotropic resolutions of 1 mm and 800 μm. These data sets are particularly suitable for resolving complex and subtle fiber architectures, including fiber crossings in the white matter, anisotropy in the cortex and fibers entering the cortex. Copyright © 2011 Elsevier Inc. All rights reserved.

A quantitative comparison of two methods to correct eddy current-induced distortions in DT-MRI.

PubMed

Muñoz Maniega, Susana; Bastin, Mark E; Armitage, Paul A

2007-04-01

Eddy current-induced geometric distortions of single-shot, diffusion-weighted, echo-planar (DW-EP) images are a major confounding factor to the accurate determination of water diffusion parameters in diffusion tensor MRI (DT-MRI). Previously, it has been suggested that these geometric distortions can be removed from brain DW-EP images using affine transformations determined from phantom calibration experiments using iterative cross-correlation (ICC). Since this approach was first described, a number of image-based registration methods have become available that can also correct eddy current-induced distortions in DW-EP images. However, as yet no study has investigated whether separate eddy current calibration or image-based registration provides the most accurate way of removing these artefacts from DT-MRI data. Here we compare how ICC phantom calibration and affine FLIRT (http://www.fmrib.ox.ac.uk), a popular image-based multi-modal registration method that can correct both eddy current-induced distortions and bulk subject motion, perform when registering DW-EP images acquired with different slice thicknesses (2.8 and 5 mm) and b-values (1000 and 3000 s/mm(2)). With the use of consistency testing, it was found that ICC was a more robust algorithm for correcting eddy current-induced distortions than affine FLIRT, especially at high b-value and small slice thickness. In addition, principal component analysis demonstrated that the combination of ICC phantom calibration (to remove eddy current-induced distortions) with rigid body FLIRT (to remove bulk subject motion) provided a more accurate registration of DT-MRI data than that achieved by affine FLIRT.

Imaging Biomarker Dynamics in an Intracranial Murine Glioma Study of Radiation and Antiangiogenic Therapy

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

Chung, Caroline, E-mail: caroline.chung@rmp.uhn.on.ca; Jalali, Shahrzad; Foltz, Warren

2013-03-01

Purpose: There is a growing need for noninvasive biomarkers to guide individualized spatiotemporal delivery of radiation therapy (RT) and antiangiogenic (AA) therapy for brain tumors. This study explored early biomarkers of response to RT and the AA agent sunitinib (SU), in a murine intracranial glioma model, using serial magnetic resonance imaging (MRI). Methods and Materials: Mice with MRI-visible tumors were stratified by tumor size into 4 therapy arms: control, RT, SU, and SU plus RT (SURT). Single-fraction conformal RT was delivered using MRI and on-line cone beam computed tomography (CT) guidance. Serial MR images (T2-weighted, diffusion, dynamic contrast-enhanced and gadolinium-enhancedmore » T1-weighted scans) were acquired biweekly to evaluate tumor volume, apparent diffusion coefficient (ADC), and tumor perfusion and permeability responses (K{sub trans}, K{sub ep}). Results: Mice in all treatment arms survived longer than those in control, with a median survival of 35 days for SURT (P<.0001) and 30 days for RT (P=.009) and SU (P=.01) mice vs 26 days for control mice. At Day 3, ADC rise was greater with RT than without (P=.002). Sunitinib treatment reduced tumor perfusion/permeability values with mean K{sub trans} reduction of 27.6% for SU (P=.04) and 26.3% for SURT (P=.04) mice and mean K{sub ep} reduction of 38.1% for SU (P=.01) and 27.3% for SURT (P=.02) mice. The magnitude of individual mouse ADC responses at Days 3 and 7 correlated with subsequent tumor growth rate R values of −0.878 (P=.002) and −0.80 (P=.01), respectively. Conclusions: Early quantitative changes in diffusion and perfusion MRI measures reflect treatment responses soon after starting therapy and thereby raise the potential for these imaging biomarkers to guide adaptive and potentially individualized therapy approaches in the future.« less

Muscle changes detected with diffusion-tensor imaging after long-distance running.

PubMed

Froeling, Martijn; Oudeman, Jos; Strijkers, Gustav J; Maas, Mario; Drost, Maarten R; Nicolay, Klaas; Nederveen, Aart J

2015-02-01

To develop a protocol for diffusion-tensor imaging (DTI) of the complete upper legs and to demonstrate feasibility of detection of subclinical sports-related muscle changes in athletes after strenuous exercise, which remain undetected by using conventional T2-weighted magnetic resonance (MR) imaging with fat suppression. The research was approved by the institutional ethics committee review board, and the volunteers provided written consent before the study. Five male amateur long-distance runners underwent an MR examination (DTI, T1-weighted MR imaging, and T2-weighted MR imaging with fat suppression) of both upper legs 1 week before, 2 days after, and 3 weeks after they participated in a marathon. The tensor eigenvalues (λ1, λ2, and λ3), the mean diffusivity, and the fractional anisotropy (FA) were derived from the DTI data. Data per muscle from the three time-points were compared by using a two-way mixed-design analysis of variance with a Bonferroni posthoc test. The DTI protocol allowed imaging of both complete upper legs with adequate signal-to-noise ratio and within a 20-minute imaging time. After the marathon, T2-weighted MR imaging revealed grade 1 muscle strains in nine of the 180 investigated muscles. The three eigenvalues, mean diffusivity, and FA were significantly increased (P < .05) in the biceps femoris muscle 2 days after running. Mean diffusivity and eigenvalues λ1 and λ2 were significantly (P < .05) increased in the semitendinosus and gracilis muscles 2 days after the marathon. A feasible method for DTI measurements of the upper legs was developed that fully included frequently injured muscles, such as hamstrings, in one single imaging session. This study also revealed changes in DTI parameters that over time were not revealed by qualitative T2-weighted MR imaging with fat suppression. © RSNA, 2014.

Magnetic resonance imaging in Alzheimer's Disease Neuroimaging Initiative 2.

PubMed

Jack, Clifford R; Barnes, Josephine; Bernstein, Matt A; Borowski, Bret J; Brewer, James; Clegg, Shona; Dale, Anders M; Carmichael, Owen; Ching, Christopher; DeCarli, Charles; Desikan, Rahul S; Fennema-Notestine, Christine; Fjell, Anders M; Fletcher, Evan; Fox, Nick C; Gunter, Jeff; Gutman, Boris A; Holland, Dominic; Hua, Xue; Insel, Philip; Kantarci, Kejal; Killiany, Ron J; Krueger, Gunnar; Leung, Kelvin K; Mackin, Scott; Maillard, Pauline; Malone, Ian B; Mattsson, Niklas; McEvoy, Linda; Modat, Marc; Mueller, Susanne; Nosheny, Rachel; Ourselin, Sebastien; Schuff, Norbert; Senjem, Matthew L; Simonson, Alix; Thompson, Paul M; Rettmann, Dan; Vemuri, Prashanthi; Walhovd, Kristine; Zhao, Yansong; Zuk, Samantha; Weiner, Michael

2015-07-01

Alzheimer's Disease Neuroimaging Initiative (ADNI) is now in its 10th year. The primary objective of the magnetic resonance imaging (MRI) core of ADNI has been to improve methods for clinical trials in Alzheimer's disease (AD) and related disorders. We review the contributions of the MRI core from present and past cycles of ADNI (ADNI-1, -Grand Opportunity and -2). We also review plans for the future-ADNI-3. Contributions of the MRI core include creating standardized acquisition protocols and quality control methods; examining the effect of technical features of image acquisition and analysis on outcome metrics; deriving sample size estimates for future trials based on those outcomes; and piloting the potential utility of MR perfusion, diffusion, and functional connectivity measures in multicenter clinical trials. Over the past decade the MRI core of ADNI has fulfilled its mandate of improving methods for clinical trials in AD and will continue to do so in the future. Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Diffusion-weighted imaging of mucinous carcinoma of the breast: evaluation of apparent diffusion coefficient and signal intensity in correlation with histologic findings.

PubMed

Woodhams, Reiko; Kakita, Satoko; Hata, Hirofumi; Iwabuchi, Keiichi; Umeoka, Shigeaki; Mountford, Carolyn E; Hatabu, Hiroto

2009-07-01

The purposes of this study were to compare the apparent diffusion coefficient (ADC) of mucinous carcinoma of the breast with that of other breast tumors and to analyze correlations between signal intensity on diffusion-weighted images and the histologic features of mucinous carcinoma. Two hundred seventy-six patients with 277 lesions, including 15 mucinous carcinomas (13 pure type, two mixed type), 204 other malignant tumors, and 58 benign lesions, were examined with 1.5-T MRI at b values of 0 and 1,500 s/mm(2). The correlations between cellularity and ADC, homogeneity of signal intensity on diffusion-weighted images, and histopathologic findings were analyzed. The difference was statistically significant (p < 0.05). The mean ADC of mucinous carcinoma (1.8 +/- 0.4 x 10(-3) mm(2)/s) was statistically higher than that of benign lesions (1.3+/- 0.3 x 10(-3) mm(2)/s) and other malignant tumors (0.9 +/- 0.2 x 10(-3) mm(2)/s) (p < 0.001). The ADC of pure type mucinous carcinoma (1.8 +/- 0.3 x 10(-3) mm(2)/s) was higher than that of mixed type mucinous carcinoma (1.2 +/- 0.2 x 10(-3) mm(2)/s) (p < 0.001) and other histologic types (p > 0.05). The correlation between mean cellularity and the ADC of mucinous carcinoma was significant (rho(s) = -0.754; p = 0.001). The homogeneity of signal intensity on diffusion-weighted images correlated with the homogeneity of histologic structures of mucinous carcinoma (p < 0.001; kappa = 0.826). Mucinous carcinoma can be clearly differentiated from other breast tumors on the basis of ADC. The low signal intensity of mucinous carcinoma on diffusion-weighted images appears to reflect the presence of mucin and low cellularity. High signal intensity on diffusion-weighted images may reflect the presence of fibrovascular bundles, increased cell density, or a combination of these features.

Evaluation of a low-carbohydrate diet-based preparation protocol without fasting for cardiac PET/MR imaging.

PubMed

Nensa, Felix; Tezgah, E; Schweins, K; Goebel, J; Heusch, P; Nassenstein, K; Schlosser, T; Poeppel, T D

2017-06-01

Assessment of increased glucose uptake in inflammatory or malignant myocardial disease using PET/MRI relies on uptake suppression in normal myocardium. We evaluated the efficacy of a ≥24 hours high-fat, low-carbohydrate, and protein-permitted diet (HFLCPP) in combination with unfractionated heparin for suppression of "physiologic" myocardial glucose uptake. PET/MRI was successfully performed in 89 patients. HFLCPP was started ≥24 hours prior to PET/MRI. All patients received i.v. injection of unfractionated heparin (50 IU·kg -1 ) 15 minutes prior to FDG administration. Left ventricular FDG uptake was visually evaluated by two readers. Diffuse myocardial uptake exceeding liver uptake, isolated uptake in the lateral wall, or diffuse uptake in the entire circumference of the heart base were defined as failed suppression. Homogeneous myocardial uptake below liver uptake with/without focal uptake was defined as successful suppression. Success rate was 84%. Suppression was unsuccessful in 14 patients. No significant influence of gender (P = .40) or age (P = .21) was found. However, insufficient suppression was more common in patients younger than 45 years (20% vs 7%). PET/MR imaging completion rate was >97%. A HFLCPP diet in combination with unfractionated heparin was successfully implemented for cardiac PET/MRI and resulted in a sufficient suppression of myocardial FDG uptake in 84% of patients.

Abbreviated MRI Protocols: Wave of the Future for Breast Cancer Screening.

PubMed

Chhor, Chloe M; Mercado, Cecilia L

2017-02-01

The purpose of this article is to describe the use of abbreviated breast MRI protocols for improving access to screening for women at intermediate risk. Breast MRI is not a cost-effective modality for screening women at intermediate risk, including those with dense breast tissue as the only risk. Abbreviated breast MRI protocols have been proposed as a way of achieving efficiency and rapid throughput. Use of these abbreviated protocols may increase availability and provide women with greater access to breast MRI.

Characterization of the murine orthotopic adamantinomatous craniopharyngioma PDX model by MRI in correlation with histology.

PubMed

Hölsken, Annett; Schwarz, Marc; Gillmann, Clarissa; Pfister, Christina; Uder, Michael; Doerfler, Arnd; Buchfelder, Michael; Schlaffer, Sven; Fahlbusch, Rudolf; Buslei, Rolf; Bäuerle, Tobias

2018-01-01

Adamantinomatous craniopharyngiomas (ACP) as benign sellar brain tumors are challenging to treat. In order to develop robust in vivo drug testing methodology, the murine orthotopic craniopharyngioma model (PDX) was characterized by magnetic resonance imaging (MRI) and histology in xenografts from three patients (ACP1-3). In ACP PDX, multiparametric MRI was conducted to assess morphologic characteristics such as contrast-enhancing tumor volume (CETV) as well as functional parameters from dynamic contrast-enhanced MRI (DCE-MRI) and diffusion-weighted imaging (DWI) including area-under-the-curve (AUC), peak enhancement (PE), time-to-peak (TTP) and apparent diffusion coefficient (ADC). These MRI parameters evaluated in 27 ACP PDX were correlated to histological features and percentage of vital tumor cell content. Qualitative analysis of MRI and histology from PDX revealed a similar phenotype as seen in patients, although the MRI appearance in mice resulted in a more solid tumor growth than in humans. CETV were significantly higher in ACP2 xenografts relative to ACP1 and ACP3 which correspond to respective average vitality of 41%, <10% and 26% determined histologically. Importantly, CETV prove tumor growth of ACP2 PDX as it significantly increases in longitudinal follow-up of 110 days. Furthermore, xenografts from ACP2 revealed a significantly higher AUC, PE and TTP in comparison to ACP3, and significantly increased ADC relative to ACP1 and ACP3 respectively. Overall, DCE-MRI and DWI can be used to distinguish vital from non-vital grafts, when using a cut off value of 15% for vital tumor cell content. MRI enables the assessment of craniopharyngioma PDX vitality in vivo as validated histologically.

Complex Geometric Models of Diffusion and Relaxation in Healthy and Damaged White Matter

PubMed Central

Farrell, Jonathan A.D.; Smith, Seth A.; Reich, Daniel S.; Calabresi, Peter A.; van Zijl, Peter C.M.

2010-01-01

Which aspects of tissue microstructure affect diffusion weighted MRI signals? Prior models, many of which use Monte-Carlo simulations, have focused on relatively simple models of the cellular microenvironment and have not considered important anatomic details. With the advent of higher-order analysis models for diffusion imaging, such as high-angular-resolution diffusion imaging (HARDI), more realistic models are necessary. This paper presents and evaluates the reproducibility of simulations of diffusion in complex geometries. Our framework is quantitative, does not require specialized hardware, is easily implemented with little programming experience, and is freely available as open-source software. Models may include compartments with different diffusivities, permeabilities, and T2 time constants using both parametric (e.g., spheres and cylinders) and arbitrary (e.g., mesh-based) geometries. Three-dimensional diffusion displacement-probability functions are mapped with high reproducibility, and thus can be readily used to assess reproducibility of diffusion-derived contrasts. PMID:19739233

Structural and functional neuroplasticity in human learning of spatial routes.

PubMed

Keller, Timothy A; Just, Marcel Adam

2016-01-15

Recent findings with both animals and humans suggest that decreases in microscopic movements of water in the hippocampus reflect short-term neuroplasticity resulting from learning. Here we examine whether such neuroplastic structural changes concurrently alter the functional connectivity between hippocampus and other regions involved in learning. We collected both diffusion-weighted images and fMRI data before and after humans performed a 45min spatial route-learning task. Relative to a control group with equal practice time, there was decreased diffusivity in the posterior-dorsal dentate gyrus of the left hippocampus in the route-learning group accompanied by increased synchronization of fMRI-measured BOLD signal between this region and cortical areas, and by changes in behavioral performance. These concurrent changes characterize the multidimensionality of neuroplasticity as it enables human spatial learning. Copyright © 2015 Elsevier Inc. All rights reserved.

Image formation in diffusion MRI: A review of recent technical developments

PubMed Central

Miller, Karla L.

2017-01-01

Diffusion magnetic resonance imaging (MRI) is a standard imaging tool in clinical neurology, and is becoming increasingly important for neuroscience studies due to its ability to depict complex neuroanatomy (eg, white matter connectivity). Single‐shot echo‐planar imaging is currently the predominant formation method for diffusion MRI, but suffers from blurring, distortion, and low spatial resolution. A number of methods have been proposed to address these limitations and improve diffusion MRI acquisition. Here, the recent technical developments for image formation in diffusion MRI are reviewed. We discuss three areas of advance in diffusion MRI: improving image fidelity, accelerating acquisition, and increasing the signal‐to‐noise ratio. Level of Evidence: 5 Technical Efficacy: Stage 1 J. MAGN. RESON. IMAGING 2017;46:646–662 PMID:28194821