Diffusion-weighted Imaging Studies Research Articles

Diffusion MRI changes in the anterior subventricular zone following chemoradiation in glioblastoma with posterior ventricular involvement.

There is growing evidence that the subventricular zone (SVZ) plays a key role in glioblastoma (GBM) tumorigenesis. However, little is known regarding how the SVZ, which is a harbor for adult neural stem cells, may be influenced by chemoradiation. The current diffusion-weighted imaging (DWI) study explored ipsilateral and contralateral alterations in the anterior SVZ in GBM patients with posterior enhancing lesions following chemoradiation. Forty GBM patients with tumor involvement in the posterior SVZ (mean age = 57 ± 10; left-hemisphere N = 25; right-hemisphere N = 15) were evaluated using DWI before and after chemoradiation. Regions-of-interest were drawn on the ipsilesional and contralesional anterior SVZ on apparent diffusion coefficient (ADC) maps for both timepoints. ADC histogram analysis was performed by modeling a bimodal, double Gaussian distribution to obtain ADCL, defined as the mean of the lower Gaussian distribution. The ipsilesional SVZ had lower ADCL values compared to the contralesional SVZ before treatment (mean difference = 0.025 μm2/ms; P = 0.007). Following chemoradiation, these changes were no longer observed (mean difference = 0.0025 μm2/ms; P > 0.5), as ADCL values of the ipsilesional SVZ increased (mean difference = 0.026 μm2/ms; P = 0.037). An increase in ipsilesional ADCL was associated with shorter progression-free (P = 0.0119) and overall survival (P = 0.0265). These preliminary observations suggest baseline asymmetry as well as asymmetric changes in the SVZ proximal (ipsilesional) to the tumor with respect to contralesional SVZ regions may be present in GBM, potentially implicating this region in tumorigenesis and/or treatment resistance.

Factors determining recurrence in transient global amnesia

BackgroundAetiology of transient global amnesia (TGA) remains uncertain, though many have been proposed, including ischaemic, migrainous or epileptic pathologies.MethodsWe attempted to determine risk factors for TGA, as well as prognostic factors that may cause recurrence. We evaluated clinical history, family history and magnetic resonance diffusion-weighted imaging (DWI) studies of 93 prospective patients with TGA. Patients were followed from 2004 to 2016. Fifteen of 93 (16%) patients experienced a recurrence of TGA.ResultsAmong precipitating events, physical activities inducing Valsalva-like manoeuvres were most common, followed by emotional stress. Eighty-four patients had possible comorbidities or risk factors for TGA, though no single risk factor was ubiquitous. Risk factors associated with recurrence were head injury (isolated vs. recurrent, 16.7% vs. 53.5%, p < 0.01), depression (isolated vs. recurrent, 15.4% vs 46.7%, p = 0.01) and family history of dementia (isolated vs. recurrent, 20.5% vs. 46.7%, p = 0.03). Of 15 patients with confirmed recurrent TGA, two developed dementia and four subjective memory impairment. DWI lesions were observed in 24 patients and were located anywhere within the hippocampus.ConclusionsDWI lesions were not significantly associated with outcomes (recurrence, subjective memory impairment, dementia). We have found that depression, previous head injury and family history of dementia may predict TGA recurrence.

Apparent Diffusion Coefficient Assessment of Brain Development in Normal Fetuses and Ventriculomegaly

Diffusion neuro-MRI has benefited significantly from sophisticated pre-processing procedures aimed at improving image quality and diagnostic. In this work, diffusion-weighted imaging (DWI) was used with artifact correction and the apparent diffusion coefficient (ADC) was quantified to investigate fetal brain development. The DWI protocol was designed in order to limit the acquisition time and to estimate ADC without perfusion bias. The ADC in normal fetal brains was compared to cases with isolated ventriculomegaly (VM), a common fetal disease whose DWI studies are still scarce. DWI was performed in 58 singleton fetuses (Gestational age (GA) range: 19-38w) at 1.5T. In 31 cases, VM was diagnosed on ultrasound. DW-Spin Echo EPI with b-values=50,200,700s/mm^2 along three orthogonal axes was used. All images were corrected for noise, Gibbs-ringing and motion artifacts. The signal-to-noise ratio (SNR) was calculated and the ADC was measured with a linear least-squared algorithm. A multi-way ANOVA was used to evaluate differences in ADC between normal and VM cases and between second and third trimester in different brain regions. Correlation between ADC and GA was assessed with linear and quadratic regression analysis. Noise and artifact correction considerably increased SNR and the goodness-of-fit. ADC measurements were significantly different between second and third trimester in centrum semiovale, frontal white matter, thalamus, cerebellum and pons of both normal and VM brains (p<0.03). ADC values were significantly different between normal and VM in centrum semiovale and frontal white matter (p<0.02). ADC values in centrum semiovale, thalamus, cerebellum and pons linearly decreased with GA both in normal and VM brains, while a quadratic relation with GA was found in basal ganglia and occipital white matter of normal brains and in frontal white matter of VM (p<0.02). ADC values in all fetal brain regions were lower than those reported in literature where DWI with b=0 was performed. Conversely, they were in agreement with the results of other authors who measured perfusion and diffusion contributions separately. By optimizing our DWI protocol we achieved an unbiased quantification of brain ADC in reasonable scan time. Our findings suggested that ADC can be a useful biomarker of brain abnormalities associated with VM.

Diffusion-Weighted and Intravoxel Incoherent Motion MRI of the pregnant cervix as a tool to monitor cervical ripening

Background and Hypothesis: Preterm delivery is a major source of infant morbidity and mortality and is difficult to predict. The process of cervical ripening prior to delivery has known histologic changes including breakdown of collagen and increasing water content. It is hypothesized that the diffusion of water, which can be measured on MRI, will increase as the cervical water content increases. Diffusion weighted imaging (DWI) is a form of MRI that measures the random Brownian motion of water molecules (represented as the apparent diffusion coefficient (ADC)). Intravoxel incoherent motion (IVIM) MRI further subdivides the ADC into microcapillary perfusion (D*) and diffusion (D). We hypothesize that as the pregnant cervix ripens near delivery, diffusion of water within the cervix (ADC and D) will increase without changes in the capillary perfusion (D*). We sought to determine the relationship between ADC, D*, D, gestational age, and time to delivery in a cohort of volunteer pregnant females.&#x0D; Experimental Design or Project Methods: DWI and IVIM MR studies from a cohort of 45 volunteer pregnant females with no known underlying fetal anomalies were examined. Subglandular and stromal cervix thickness and cervical length were measured along with the ADC, D*, and D of the subglandular and stromal cervix. Gestational history and delivery information was documented.&#x0D; Results: Subglandular ADC inversely correlated with time to delivery (r=-0.393, p=0.052). Although not significant, subglandular D revealed a trend of increasing with increased gestation age (r=0.261, p=0.149). Subglandular ADC also varied inversely with thickness of the subglandular cervix (r=-0.352, p=0.047). Subglandular D* varied inversely with maternal age (r=-0.380, p=0.028).&#x0D; Conclusion and Potential Impact: Our data support the hypothesized trend of increased diffusion of water within the cervix with unchanged capillary perfusion as a normal pregnancy progressed throughout the second and third trimesters. This study suggests that diffusion measures (ADC and D) follow a predictable progression during the course of a normal pregnancy and have the potential to provide a means of predicting preterm labor in the setting of preterm cervical ripening.

536P - A prospective study of diffusion-weighted magnetic resonance imaging for predicting outcome following chemoradiotherapy, in squamous cell carcinomas of the anus

BackgroundAnal Squamous Cell Carcinoma (ASCC) is radically treated by chemoradiotherapy (CRT). The use of DW-MRI as a predictive marker of outcome would enable early individualisation of treatment. We aimed to quantify the changes in mean apparent-diffusion-coefficient (ADCMean) between a DW-MRI at diagnosis and on fraction 8-10 of CRT as a biomarker for cellularity, and correlate these with outcome. MethodsThis prospective study recruited patients with ASCC between October 2014 and November 2017. DW-MRI was performed at diagnosis and after fraction 8-10 of radical CRT. A region of interest (ROI) was delineated for all primary tumours and any lymph nodes >2cm on high-resolution T2 –weighted images and propagated to the ADC map. A pre-defined cut-off for percentage change in ADCMean (ΔADC) was set at<20%. Complete response (CR) was assessed 3 months following completion of CRT. Routine clinical follow up data from patients were collected from NHS electronic systems. ResultsTwenty-three of 29 recruited patients underwent paired DW-MRI scans. The median (range) tumour volume was 13.6 cm3 (2.8 cm3 to 84.9 cm3). The median ΔADCMean between scans was 20.7% (95% CI: 12.7%, 34.1%). Nine of 23 (43%) patients had a change of ADCMean <20%. Two patients failed to achieve a CR, with ΔADCMean of 14.6% and 20.3%, respectively. On routine follow up, 2 further patients had relapsed, with ΔADCMean of -1.2% and 6.8%. ConclusionsIn a subset of patients, <20% ΔADCMean on DW-MRI between diagnosis and day 8-10 of CRT was observed. Four patients in the study demonstrated persistent or recurrent disease, all of whom demonstrated an ADC on or below the pre-specified cut-off. Further investigation of the predictive merit of DW-MRI change, and the optimum cut-off is needed in larger cohorts. Clinical trial identificationNCT02145416. Legal entity responsible for the studyUniversity of Oxford. FundingCRUK EPSRC Cancer Imaging Centre in Oxford, the CRUK Oxford Centre and the NIHR.M Hawkins is supported by Medical Research Council grant MC_UU_00001/2. DisclosureR. Muirhead: Honoraria (self), Fee for lecture: Boehringer Ingelheim. V. Goh: Research grant / Funding (self): Siemens. All other authors have declared no conflicts of interest.

Study of diffusion-weighted magnetic resonance imaging in the evaluation of the response to AAV2-VEGF-Trap neoadjuvant treatment in a triple-negative breast cancer animal model.

ObjectiveEvaluation of the efficacy of adeno‐associated virus 2 mediated gene transfer of vascular endothelial growth factor Trap (AAV2‐VEGF‐Trap) alone or combination with paclitaxel in a mouse model of triple‐negative breast cancer (TNBC) using diffusion‐weighted magnetic resonance imaging (DW‐MRI) and in vivo fluorescence imaging.Materials and MethodsXenografted TNBC tumors were established by subcutaneous injection of MDA‐MB‐231 cells into nude mice. Tumors were treated with AAV2‐VEGF‐Trap, paclitaxel, AAV2‐VEGF‐Trap combined with paclitaxel and control. A 7.0‐Tesla magnetic resonance (MR) was used to obtain the apparent diffusion coefficient (ADC) values and ΔADC values. In vivo fluorescence imaging coupled with the optical imaging probe AngioSense680 EX was acquired to obtain average luminous intensity values. Immunohistochemical staining of tumor Ki‐67 and vascular endothelial cell marker antigen (CD31) were used to evaluate the effects on tumor proliferation and angiogenesis.ResultsThe combination of AAV2‐VEGF‐Trap with paclitaxel exhibited greater tumor growth inhibition compared with the other groups. The ADC values in the paclitaxel group and the AAV2‐VEGF‐Trap in combination with paclitaxel group were significant greater compared with the control group, and the ΔADC values of all treatment groups were significantly increased compared with the control group on the 14th day after administration. Decreased microvessel density and luminous intensity in the treatment groups that contain AAV2‐VEGF‐Trap were observed. Reduced proliferation activity was noted in groups that contained paclitaxel.ConclusionAAV2‐VEGF‐Trap inhibits TNBC growth though inhibiting tumor neovascularization with a single intravenous injection, and AAV2‐VEGF‐Trap exhibits a synergistic effect when used in combination with paclitaxel for TNBC neoadjuvant therapy. In vivo fluorescence imaging can detect the anti‐angiogenesis effect of AAV2‐VEGF‐Trap early and noninvasively. DW‐MRI can longitudinally monitor the neoadjuvant efficacy of TNBC.

Quantitative MR neurography of brachial plexus lesions based on diffusivity measurements

ObjectivesNew magnetic resonance imaging (MRI) based on 3D fat-suppressed techniques provide high accuracy for evaluation of brachial plexus and peripheral nerve lesions from a qualitative point of view. However, this qualitative evaluation often demonstrates overlapping features among different pathologies (Pullman et al., 2013). Diffusion weighted imaging (DWI) and diffusion tensor imaging (DTI) are functional MRI techniques that have been successfully applied in the imaging of central nervous system lesions, and now are being imported, with promising results for peripheral nerve and plexus evaluation. Several derived parameters from DWI and DTI studies such as apparent diffusion coefficient (ADC) or fractional anisotropy (FA), can be used as potential biomarkers of neural damage by providing information about axonal flow, fiber organization or myelin integrity (Andreou et al., 2015). In this study we assess the role of DW and DT based quantitative measures in characterization of traumatic and non traumatic lesions of brachial plexus and peripheral nerve and its influence on therapeutic management and outcome. Methods34 patients with features ofbrachialplexopathy and peripheral neuropathy were included in the study. MR neurography examinations included conventional MR sequences and unidirectional DW-MRN with background suppression (DWIBS) and DTI. The images were independently reviewed by two radiologists and the findings were recorded at different levels of thebrachial plexus: ganglia, roots, trunks, divisions and cords. Mean ADC and FA values were determined within each lesion and within contra lateral homologous unaffected segment of the plexus. The Mann-Whitney Test was used to calculate the differences in ADC&FA values between diseased and normal sides and the One way ANOVA test between diseased segments of different pathologies with p-values <0.05 being considered statistically significant. Resultspatients were classified according to etiologic causes into four categories: traumatic, compressive degenerative disk, radiation induced plexitis and neoplastic nerve compression or invasion. T2 high signal intensity and swelling of the affected nerve, muscular denervation and complication such as pseudo meningeocele and neuroma were the major findings in qualitatitve sequences. A statistically significant difference in ADC and FA values were found between diseased and normal sides as well as across the traumatic and non traumatic groups and between benign compressive and malignant infiltrative etiologies. ConclusionThe resulted values of newly designed quantitative protocols give us functional and numerical marker by which the diagnosis and differentiation of different pathologies of peripheral nerves and brachial plexus will be more suitable.

Association of Tumor [18F]FDG Activity and Diffusion Restriction with Clinical Outcomes of Rhabdomyosarcomas.

To evaluate whether the extent of restricted diffusion and 2-deoxy-2-[18F] fluoro-D-glucose ([18F]FDG) uptake of pediatric rhabdomyosarcomas (RMS) on positron emission tomography (PET)/magnetic resonance (MR) images provides prognostic information. In a retrospective, IRB-approved study, we evaluated [18F]FDG PET/CT and diffusion-weighted (DW) MR imaging studies of 21 children and adolescents (age 1-20years) with RMS of the head and neck. [18F]FDG PET and DW MR scans at the time of the initial tumor diagnosis were fused using MIM software. Quantitative measures of the tumor mass with restricted diffusion, [18F]FDG hypermetabolism, or both were dichotomized at the median and tested for significance using Gray's test. Data were analyzed using a survival analysis and competing risk model with death as the competing risk. [18F]FDG PET/MR images demonstrated a mismatch between tumor areas with increased [18F]FDG uptake and restricted diffusion. The DWI, PET, and DWI + PET tumor volumes were dichotomized at their median values, 23.7, 16.4, and 9.5cm3, respectively, and were used to estimate survival. DWI, PET, and DWI + PET overlap tumor volumes above the cutoff values were associated with tumor recurrence, regardless of post therapy COG stage (p = 0.007, p = 0.04, and p = 0.07, respectively). The extent of restricted diffusion within RMS and overlap of hypermetabolism plus restricted diffusion predict unfavorable clinical outcomes.

Distributed performance of white matter properties in chess players: A DWI study using automated fiber quantification

The aim of this study is to verify whether anatomical changes occur in the brains of chess players. Besides, it is a potential attempt to evaluate diffusion properties along the tracts due to the diverse situations at anatomical level in different locations; moreover, conventional voxel-based analysis (VBA) has already been used to calculate the average values within the voxels in the investigated regions as analysis data. In this study, we used automated fiber quantification (AFQ) to automatically identify the major tracts that are related to functional domains of the human brain. AFQ can quantify pointwise white matter (WM) properties to detect specific local differences. We selected chess players with superior logical cognition abilities as the carrier to conduct our AFQ experiments. The diffusion properties of the 20 major tracts of professional chess players (n = 28) and matched controls (n = 29) were calculated using diffusion weighted imaging (DWI) data. We noted significant differences (p < 0.05) in the diffusion properties of some successive locations among 100 equidistant points in several tracts, especially in the left superior longitudinal fasciculus(SLF) and right inferior fronto-occipital fasciculus (IFOF). Professional chess players exhibited increase levels in the studied diffusion metrics with Pearson results paralleled the findings. Afterwards, considering the starting and terminating regions of SLF, IFOF, and thalamic radiation, the connectivity of gray matter (GM) where connections are active in the frontal lobe, temporal lobe, and thalamus was assessed to help with the further experiment. The results confirmed the tendency in which anatomical alterations generated different performances along the tracts; furthermore, long-term cognitive activities, such as chess, may systematically influence the WM properties of early memory, attention, and visual pathways.

A diffusion-matched principal component analysis (DM-PCA) based two-channel denoising procedure for high-resolution diffusion-weighted MRI.

Over the past several years, significant efforts have been made to improve the spatial resolution of diffusion-weighted imaging (DWI), aiming at better detecting subtle lesions and more reliably resolving white-matter fiber tracts. A major concern with high-resolution DWI is the limited signal-to-noise ratio (SNR), which may significantly offset the advantages of high spatial resolution. Although the SNR of DWI data can be improved by denoising in post-processing, existing denoising procedures may potentially reduce the anatomic resolvability of high-resolution imaging data. Additionally, non-Gaussian noise induced signal bias in low-SNR DWI data may not always be corrected with existing denoising approaches. Here we report an improved denoising procedure, termed diffusion-matched principal component analysis (DM-PCA), which comprises 1) identifying a group of (not necessarily neighboring) voxels that demonstrate very similar magnitude signal variation patterns along the diffusion dimension, 2) correcting low-frequency phase variations in complex-valued DWI data, 3) performing PCA along the diffusion dimension for real- and imaginary-components (in two separate channels) of phase-corrected DWI voxels with matched diffusion properties, 4) suppressing the noisy PCA components in real- and imaginary-components, separately, of phase-corrected DWI data, and 5) combining real- and imaginary-components of denoised DWI data. Our data show that the new two-channel (i.e., for real- and imaginary-components) DM-PCA denoising procedure performs reliably without noticeably compromising anatomic resolvability. Non-Gaussian noise induced signal bias could also be reduced with the new denoising method. The DM-PCA based denoising procedure should prove highly valuable for high-resolution DWI studies in research and clinical uses.

T240. Relationship Between Cognitive Performance and Superficial White Matter Integrity in the Cingulate Cortex in Schizophrenia: A DWI Study Using a Novel Atlas

Evidence is mounting to suggest that changes in superficial white matter (SWM) U-shaped short-range fibers are integral components of schizophrenia neuropathology, a theory that is supported by findings from postmortem studies and less often in vivo in patients with SZ. This diffusion weighted imaging (DWI) study aimed to investigate SWM in people with SZ and to determine its relationship with cognition.

IShim and Water Excitation Improves the Signal-to-Noise Ratio on q-Space Imaging: A Single-Center Clinical Study

Purpose: This study aimed to examine whether the signal-to-noise ratio (SNR) could be increased by combining integrated slice-by-slice shimming (iShim) with a fat suppression (FS) method other than short-tau inversion recovery (STIR) in diffusion-weighted imaging (DWI) and q-space imaging (qsi). Methods: We acquired DWI images (b-values: 0 and nine steps from 400 to 10,000 s/mm2 for six axes) using a prototypical single-shot echo planar imaging sequence by combining two types of shimming (3D Shim and iShim) and two types of FS (STIR and water excitation [WE]) in 10 volunteers. In the DWI study, the SNR for each b-value, FS effect in the b0 image, and distortion in the added image (b0 - b10,000) were evaluated for the above-mentioned four imaging methods. qsi involved original DWI images. In the qsi study, the SNR was evaluated. Results: With regard to both 3D Shim and iShim, the SNRs were significantly higher when using WE than when using STIR in b0 - b900 images (p < 0.01). For 3D Shim, however, the SNR increase effect of WE disappeared (p < 0.01) at b1600 or higher. For iShim, the SNR increase effect of WE was maintained up to b3600 (p < 0.01). The FS effect of STIR was superior to that of WE (p < 0.01). Although WE had a weak FS effect, its FS effect was greater with iShim than with 3D Shim (p < 0.01). In added images, with iShim, the spinal cord area became significantly smaller (p < 0.05), resulting in a less distorted image when compared with the 3D shim image. On qsi, with regard to both 3D Shim and iShim, the SNRs were significantly higher when using WE than when using STIR (3D Shim: p < 0.05; iShim: p < 0.01). The SNR of iShim/WE was superior to that of 3D Shim/WE (p < 0.05). Conclusion: The combination of iShim and WE has a high SNR on qsi.

Diffusion-Weighted Magnetic Resonance Imaging.

Magnetic resonance imaging (MRI) is a technique based on the contents and relaxation features of water in tissues. In basic MRI sequences, diffusion phenomenon of water molecules is not taken into account although it has a notable influence in the relaxation times, and therefore in the signal intensity of images. In fact, MRI techniques that take advantage of water diffusion have experienced a huge development in last years. Diffusion-weighted imaging (DWI) has spectacularly evolved reaching nowadays a great impact both in clinical and preclinical imaging-especially in the neuroimaging field-and in basic research. We present here a protocol to perform DWI studies in a high-field preclinical setup.

Diffusion weighted imaging demystified: the technique and potential clinical applications for soft tissue imaging.

Diffusion-weighted imaging (DWI) is a fast, non-contrast technique that is readily available and easy to integrate into an existing imaging protocol. DWI with apparent diffusion coefficient (ADC) mapping offers a quantitative metric for soft tissue evaluation and provides information regarding the cellularity of a region of interest. There are several available methods of performing DWI, and artifacts and pitfalls must be considered when interpreting DWI studies. This review article will review the various techniques of DWI acquisition and utility of qualitative as well as quantitative methods of image interpretation, with emphasis on optimal methods for ADC measurement. The current clinical applications for DWI are primarily related to oncologic evaluation: For the assessment of de novo soft tissue masses, ADC mapping can serve as a useful adjunct technique to routine anatomic sequences for lesion characterization as cyst or solid and, if solid, benign or malignant. For treated soft tissue masses, the role of DWI/ADC mapping in the assessment of treatment response as well as recurrent or residual neoplasm in the setting of operative management is discussed, especially when intravenous contrast medium cannot be given. Emerging DWI applications for non-neoplastic clinical indications are also reviewed.

Sex-specific effects of COMT Val158Met polymorphism on corpus callosum structure: A whole-brain diffusion-weighted imaging study.

BackgroundGenetic polymorphisms play a significant role in determining brain morphology, including white matter structure and may thus influence the development of brain functions. The main objective of this study was to examine the effect of Val158Met (rs4680) polymorphism of Catechol‐O‐Methyltransferase (COMT) gene on white matter connectivity in healthy adults.MethodsWe used a whole‐brain diffusion‐weighted imaging method with Tract‐Based Spatial Statistics (TBSS) analysis to examine white matter structural integrity in intrinsic brain networks on a sample of healthy subjects (N = 82).ResultsResults revealed a sex‐specific effect of COMT on corpus callosum (CC): in males only, Val homozygotes had significantly higher fractional anisotropy (FA) compared to Met‐carriers. Volume‐of‐interest analysis showed a genotype by sex interaction on FA in genu and rostral midbody of CC, whereby Val males demonstrated higher FA than Met females.ConclusionsThese results demonstrate the key effect of genes by sex interaction, rather than their individual contribution, on the corpus callosum anatomy.

Quantitative magnetic resonance (MR) neurography for evaluation of peripheral nerves and plexus injuries.

Traumatic conditions of peripheral nerves and plexus have been classically evaluated by morphological imaging techniques and electrophysiological tests. New magnetic resonance imaging (MRI) studies based on 3D fat-suppressed techniques are providing high accuracy for peripheral nerve injury evaluation from a qualitative point of view. However, these techniques do not provide quantitative information. Diffusion weighted imaging (DWI) and diffusion tensor imaging (DTI) are functional MRI techniques that are able to evaluate and quantify the movement of water molecules within different biological structures. These techniques have been successfully applied in other anatomical areas, especially in the assessment of central nervous system, and now are being imported, with promising results for peripheral nerve and plexus evaluation. DWI and DTI allow performing a qualitative and quantitative peripheral nerve analysis, providing valuable pathophysiological information about functional integrity of these structures. In the field of trauma and peripheral nerve or plexus injury, several derived parameters from DWI and DTI studies such as apparent diffusion coefficient (ADC) or fractional anisotropy (FA) among others, can be used as potential biomarkers of neural damage providing information about fiber organization, axonal flow or myelin integrity. A proper knowledge of physical basis of these techniques and their limitations is important for an optimal interpretation of the imaging findings and derived data. In this paper, a comprehensive review of the potential applications of DWI and DTI neurographic studies is performed with a focus on traumatic conditions, including main nerve entrapment syndromes in both peripheral nerves and brachial or lumbar plexus.

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

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 mm2/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.

Nonenhancing peritumoral hyperintense lesion on diffusion-weighted imaging in glioblastoma: a novel diagnostic and specific prognostic indicator.

OBJECTIVE Glioblastoma differentials include intracranial tumors, like malignant lymphomas and metastatic brain tumors with indiscernible radiological characteristics. The purpose of this study was to identify a distinct radiological feature for the preoperative differentiation of glioblastoma from its differentials, which include malignant lymphomas and metastatic brain tumors. METHODS Preoperative MR images, including diffusion-weighted imaging (DWI) studies (b = 1000 and 4000 sec/mm2), obtained in patients with newly diagnosed malignant tumor, were analyzed retrospectively after receiving approval from the institutional review board. Sixty-four patients with histologically confirmed glioblastoma, 32 patients with malignant lymphoma, and 46 patients with brain metastases were included. The presence of a nonenhancing peritumoral DWI high lesion (NePDHL, i.e., hyperintense lesion in a nonenhancing peritumoral area on DWI) was confirmed in both DWI sequences. Gray matter lesions were excluded. Lesions were termed "definite" if present within 3 cm of the hyperintense tumor border with a signal intensity ratio ≥ 30% when compared with the contralateral normal white matter in both sequences. Discriminant analysis between the histological diagnosis and the presence of Definite-NePDHL was performed, as well as Kaplan-Meier survival analysis incorporating the existence of Definite-NePDHL. RESULTS In 25% of glioblastoma patients, Definite-NePDHL was present, while it was conspicuously absent in patients with malignant lymphoma and metastatic brain tumors. The specificity and positive predictive value were 100%. In the glioblastoma subset, a higher preoperative Karnofsky Performance Scale score (p = 0.0028), high recursive partitioning analysis class (p = 0.0006), and total surgical removal (p = 0.0012) were associated with better median overall survival. Patients with Definite-NePDHL had significantly early local (p = 0.0467) and distant/dissemination recurrence (p < 0.0001) and poor prognosis (p = 0.0007). CONCLUSIONS The presence of Definite-NePDHL is very specific for glioblastoma and indicates poor prognosis. Definite-NePDHL is a significant indicator of early local and distant/dissemination recurrence in patients with glioblastoma. Studying peritumoral DWI and high-b-value DWI is useful for tumor differentiation.

Longitudinal diffusion changes in prodromal and early HD: Evidence of white-matter tract deterioration.

Huntington's disease (HD) is a genetic neurodegenerative disorder that primarily affects striatal neurons. Striatal volume loss is present years before clinical diagnosis; however, white matter degradation may also occur prior to diagnosis. Diffusion-weighted imaging (DWI) can measure microstructural changes associated with degeneration that precede macrostructural changes. DWI derived measures enhance understanding of degeneration in prodromal HD (pre-HD). As part of the PREDICT-HD study, N = 191 pre-HD individuals and 70 healthy controls underwent two or more (baseline and 1-5 year follow-up) DWI, with n = 649 total sessions. Images were processed using cutting-edge DWI analysis methods for large multicenter studies. Diffusion tensor imaging (DTI) metrics were computed in selected tracts connecting the primary motor, primary somato-sensory, and premotor areas of the cortex with the subcortical caudate and putamen. Pre-HD participants were divided into three CAG-Age Product (CAP) score groups reflecting clinical diagnosis probability (low, medium, or high probabilities). Baseline and longitudinal group differences were examined using linear mixed models. Cross-sectional and longitudinal differences in DTI measures were present in all three CAP groups compared with controls. The high CAP group was most affected. This is the largest longitudinal DWI study of pre-HD to date. Findings showed DTI differences, consistent with white matter degeneration, were present up to a decade before predicted HD diagnosis. Our findings indicate a unique role for disrupted connectivity between the premotor area and the putamen, which may be closely tied to the onset of motor symptoms in HD. Hum Brain Mapp 38:1460-1477, 2017. © 2017 Wiley Periodicals, Inc.

The Pathological Control Study of Diffusion-Weighted Magnetic Resonance Imaging (DWI) and Computed Tomography Scan in the Determination of Lesion Length for Esophageal Carcinoma

The Pathological Control Study of Diffusion-Weighted Magnetic Resonance Imaging (DWI) and Computed Tomography Scan in the Determination of Lesion Length for Esophageal Carcinoma