Magnetization-prepared Rapid Acquisition Gradient Echo Research Articles

Reduced CA2–CA3 Hippocampal Subfield Volume Is Related to Depression and Normalized by l-DOPA in Newly Diagnosed Parkinson’s Disease

Hippocampal dysfunctions may play an important role in the non-motor aspects of Parkinson’s disease (PD), including depressive and cognitive symptoms. Fine structural alterations of the hippocampus and their relationship with symptoms and medication effects are unknown in newly diagnosed PD. We measured the volume of hippocampal subfields in 35 drug-naïve, newly diagnosed PD patients without cognitive impairment and 30 matched healthy control individuals. Assessments were performed when the patients did not receive medications and after a 24-week period of l-DOPA treatment. We obtained a T1-weighted 3D magnetization-prepared rapid acquisition gradient echo image at each assessment. FreeSurfer v6.0 was used for image analysis. Results revealed a selectively decreased CA2–CA3 volume in non-medicated PD patients, which was normalized after the 24-week treatment period. Higher depressive symptoms were associated with smaller CA2–CA3 volumes. These results indicate that the CA2–CA3 subfield is structurally affected in the earliest stage of PD in the absence of cognitive impairment. This structural anomaly, normalized by l-DOPA, is related to depressive non-motor symptoms.

In vivo MRI of the human finger at 7 T.

PurposeTo demonstrate a dedicated setup for ultrahigh resolution MR imaging of the human finger in vivo.MethodsA radiofrequency coil was designed for optimized signal homogeneity and sensitivity in the finger at ultrahigh magnetic field strength (7 T), providing high measurement sensitivity. Imaging sequences (2D turbo‐spin echo (TSE) and 3D magnetization‐prepared rapid acquisition gradient echo (MPRAGE)) were adapted for high spatial resolution and good contrast of different tissues in the finger, while keeping acquisition time below 10 minutes. Data was postprocessed to display finger structures in three dimensions.Results3D MPRAGE data with isotropic resolution of 200 µm, along with 2D TSE images with in‐plane resolutions of 58 × 78 µm2 and 100 × 97 µm2, allowed clear identification of various anatomical features such as bone and bone marrow, tendons and annular ligaments, cartilage, arteries and veins, nerves, and Pacinian corpuscles.ConclusionUsing this dedicated finger coil at 7 T, together with adapted acquisition sequences, it is possible to depict the internal structures of the human finger in vivo within patient‐compatible measurement time. It may serve as a tool for diagnosis and treatment monitoring in pathologies ranging from inflammatory or erosive joint diseases to injuries of tendons and ligaments to nervous or vascular disorders in the finger. Magn Reson Med 79:588–592, 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.

Relationship between aging and T1 relaxation time in deep gray matter: A voxel-based analysis.

To investigate age-related changes in T1 relaxation time in deep gray matter structures in healthy volunteers using magnetization-prepared 2 rapid acquisition gradient echoes (MP2RAGE). In all, 70 healthy volunteers (aged 20-76, mean age 42.6 years) were scanned at 3T magnetic resonance imaging (MRI). A MP2RAGE sequence was employed to quantify T1 relaxation times. After the spatial normalization of T1 maps with the diffeomorphic anatomical registration using the exponentiated Lie algebra algorithm, voxel-based regression analysis was conducted. In addition, linear and quadratic regression analyses of regions of interest (ROIs) were also performed. With aging, voxel-based analysis (VBA) revealed significant T1 value decreases in the ventral-inferior putamen, nucleus accumbens, and amygdala, whereas T1 values significantly increased in the thalamus and white matter as well (P < 0.05 at cluster level, false discovery rate). ROI analysis revealed that T1 values in the nucleus accumbens linearly decreased with aging (P = 0.0016), supporting the VBA result. T1 values in the thalamus (P < 0.0001), substantia nigra (P = 0.0003), and globus pallidus (P < 0.0001) had a best fit to quadratic curves, with the minimum T1 values observed between 30 and 50 years of age. Age-related changes in T1 relaxation time vary by location in deep gray matter. 2 Technical Efficacy: Stage 2 J. MAGN. RESON. IMAGING 2017;46:724-731.

T42 - Assessing Genetic Control Over Brain Morphology Variance In Psychosis: A Genome-Wide Variance-Controling Qtl (Vqtl) Neuroimaging Study

Background Most imaging genetic studies on psychosis have relied upon conventional quantitative trait locus (QTL) analysis, which examines whether distinct allelic variants in a DNA locus are associated with the mean difference in the quantitative measure of a phenotypic trait, e.g. mean brain volumes. However, alternative genotypes can also moderate the variance heterogeneity of a phenotype, which is frequently referred to as variance-controlling QTL (vQTL). This type of genetic control has been observed across several species and traits, and is usually associated to genetic sensitivity to environmental fluctuation. This is highly relevant for an application in imaging genetics in light of the influential diathesis-stress model of psychopathology. To the best of our knowledge, no previous study has evaluated the presence of vQTLs for brain morphology. Methods Participants: The sample analyzed so far consists of 504 individuals recruited through the ongoing Thematically Organized Psychosis (TOP) study, which includes 216 healthy controls (HC), and 288 patients with psychosis (SZ: 143, BD: 145). Patients were diagnosed using the structured clinical interview for DSM-IV (SCID) by trained clinicians. Genetic data: The participants were genotyped with the Affymetrix Genome-Wide Human SNP Array 6.0 (Affymetrix Inc, Santa Clara, CA, USA). Quality control was performed using PLINK. Brain imaging: Magnetic resonance imaging (MRI) structural data were acquired using a 3D T1-weighted magnetization prepared rapid acquisition gradient echo (MPRAGE) sequence, and the T1-weighted scans were processed using FreeSurfer, to obtain estimated of cortical thickness/area/volume and subcortical volumes. vQTL assessment: The relationship between genome-wide single nucleotide polymorphism (SNP) variants and the phenotypic variance of each brain feature of interest was assessed by means of double generalized linear models, and multiple testing adjustments were later performed. Results Exploratory analyses revealed no significant between-group differences in variance for the brain features considered. Genome-wide vQTL analyses indicated that the population variance of features such as cerebellar volume and temporal pole cortical thickness could be under partial genetic control. Replication of these findings and diagnose-genotype interaction tests are currently being implemented and are expected to be competed by early autumn 2016. Discussion The findings suggest that inter-individual variability in brain morphometry may be influenced by specific genetic variants. Carriers of those genotypes may be particularly susceptible to brain deficits and psychopathology after exposure to pathogenic environments and, simultaneously, have increased likelihood of benefiting from enriched/non-adverse experiences.

Black-blood thrombus imaging (BTI): a contrast-free cardiovascular magnetic resonance approach for the diagnosis of non-acute deep vein thrombosis

BackgroundDeep vein thrombosis (DVT) is a common but elusive illness that can result in long-term disability or death. Accurate detection of thrombosis and assessment of its size and distribution are critical for treatment decision-making. In the present study, we sought to develop and evaluate a cardiovascular magnetic resonance (CMR) black-blood thrombus imaging (BTI) technique, based on delay alternating with nutation for tailored excitation black-blood preparation and variable flip angle turbo-spin-echo readout, for the diagnosis of non-acute DVT.MethodsThis prospective study was approved by institutional review board and informed consent obtained from all subjects. BTI was first conducted in 11 healthy subjects for parameter optimization and then conducted in 18 non-acute DVT patients to evaluate its diagnostic performance. Two clinically used CMR techniques, contrast-enhanced CMR venography (CE-MRV) and three dimensional magnetization prepared rapid acquisition gradient echo (MPRAGE), were also conducted in all patients for comparison. All images obtained from patients were analyzed on a per-segment basis. Using the consensus diagnosis of CE-MRV as the reference, the sensitivity (SE), specificity (SP), positive and negative predictive values (PPV and NPV), and accuracy (ACC) of BTI and MPRAGE as well as their diagnostic agreement with CE-MRV were calculated. Besides, diagnostic confidence and interreader diagnostic agreement were evaluated for all three techniques.ResultsBTI with optimized parameters effectively nulled the venous blood flow signal and allowed directly visualizing the thrombus within the black-blood lumen. Higher SE (90.4% vs 67.6%), SP (99.0% vs. 97.4%), PPV (95.4% vs. 85.6%), NPV (97.8% vs 92.9%) and ACC (97.4% vs. 91.8%) were obtained by BTI in comparison with MPRAGE. Good diagnostic confidence and excellent diagnostic and interreader agreements were achieved by BTI, which were superior to MPRAGE on detecting the chronic thrombus.ConclusionBTI allows direct visualization of non-acute DVT within the dark venous lumen and has the potential to be a reliable diagnostic tool without the use of contrast medium.

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

PurposeTo implement a fast (~15min) MRI protocol for carotid plaque screening using 3D multi-contrast MRI sequences without contrast agent on a 3Tesla MRI scanner. Materials and methods7 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. ResultsAverage 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. ConclusionThe 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.

Incidental ferumoxytol artifacts in clinical brain MR imaging

Ferumoxytol (Feraheme) is a parenteral therapy approved for treatment of iron deficiency anemia. The product insert for ferumoxytol states that it may affect the diagnostic ability of MRI for up to 3months. However, the expected effects may not be commonly recognized among clinical neuroradiologists. Our purpose is to describe the artifacts we have seen at our institution during routine clinical practice. We reviewed the patients at our institution that had brain MRI performed within 90days of receiving intravenous ferumoxytol. The imaging was reviewed for specific findings, including diffusion-weighted imaging vascular susceptibility artifact, gradient-echo echo-planar T2*-weighted vascular susceptibility artifact, SWI/SWAN vascular susceptibility artifact, hypointense vascular signal on T2-weighted images, pre-gadolinium contrast vascular enhancement on magnetization-prepared rapid acquisition gradient echo (MPRAGE) imaging, and effects on post-gadolinium contrast T1 imaging. Multiple artifacts were observed in patients having a brain MRI within 3days of receiving intravenous ferumoxytol. These included susceptibility artifact on DWI, GRE, and SWAN/SWI imaging, pre-gadolinium contrast increased vascular signal on MPRAGE imaging, and decreased expected enhancement on post-gadolinium contrast T1-weighted imaging. Ferumoxytol can create imaging artifacts which complicate clinical interpretation when brain MRI is performed within 3days of administration. Recognition of the constellation of artifacts produced by ferumoxytol is important in order to obviate additional unnecessary examinations and mitigate errors in interpretation.

Motion-insensitive carotid intraplaque hemorrhage imaging using 3D inversion recovery preparation stack of stars (IR-prep SOS) technique.

Carotid artery imaging is important in the clinical management of patients at risk for stroke. Carotid intraplaque hemorrhage (IPH) presents an important diagnostic challenge. 3D magnetization prepared rapid acquisition gradient echo (MPRAGE) has been shown to accurately image carotid IPH; however, this sequence can be limited due to motion- and flow-related artifact. The purpose of this work was to develop and evaluate an improved 3D carotid MPRAGE sequence for IPH detection. We hypothesized that a radial-based k-space trajectory sequence such as "Stack of Stars" (SOS) incorporated with inversion recovery preparation would offer reduced motion sensitivity and more robust flow suppression by oversampling of central k-space. A total of 31 patients with carotid disease (62 carotid arteries) were imaged at 3T magnetic resonance imaging (MRI) with 3D IR-prep Cartesian and SOS sequences. Image quality was determined between SOS and Cartesian MPRAGE in 62 carotid arteries using t-tests and multivariable linear regression. Kappa analysis was used to determine interrater reliability. In all, 25 among 62 carotid plaques had carotid IPH by consensus from the reviewers on SOS compared to 24 on Cartesian sequence. Image quality was significantly higher with SOS compared to Cartesian (mean 3.74 vs. 3.11, P < 0.001). SOS acquisition yielded sharper image features with less motion (19.4% vs. 45.2%, P < 0.002) and flow artifact (27.4% vs. 41.9%, P < 0.089). There was also excellent interrater reliability with SOS (kappa = 0.89), higher than that of Cartesian (kappa = 0.84). By minimizing flow and motion artifacts and retaining high interrater reliability, the SOS MPRAGE has important advantages over Cartesian MPRAGE in carotid IPH detection. 1 J. Magn. Reson. Imaging 2017;45:410-417.

A Frameless Stereotactic Implantation Technique for Depth Electrodes in Refractory Epilepsy Using Intraoperative Magnetic Resonance Imaging

Various complex techniques for depth electrode insertion in refractory epilepsy using preoperative imaging have been investigated. We evaluated a simple, accurate, cost-effective, and timesaving method using intraoperative magnetic resonance imaging (MRI). A neuronavigation-guided insertion tube attached to bone facilitated the placement of stereotactic percutaneous drill holes, bolt implantation, and frameless stereotactic insertion of depth electrodes. Image registration was carried out by head coil fiducials with trajectory planning and intraoperative electrode correction. In 6 patients with refractory epilepsy (3 women and 3 men; mean age, 30.0 years; range, 20-37 years), 58 depth electrodes (9-11 per patient) were placed. The mean length of the inserted electrodes was 37.3 mm ± 8.8 (mean ± SD) (range, 22.1-84.4 mm). The overall target point accuracy was 3.2 mm ± 2.2 (range, 0-8.6 mm), which was significantly different from the overall entry point accuracy of 1.4 mm ± 1.2 (P < 0.0001). All electrodes functioned perfectly, enabling high-quality stereo-electroencephalography recordings over a period of 7.3 days ± 0.5 (range, 7-8 days). The mean implantation time for 9-11 electrodes per patient was 115 minutes ± 36.3 (range, 75-160 minutes; 12 minutes for 1 electrode on average) including the intraoperative MRI (T1 three-dimensional magnetization-prepared rapid acquisition gradient echo, T2, and diffusion tensor imaging). There was no hemorrhage, infection, or neurologic deficit related to the procedure. Our frameless technique of depth electrode insertion using intraoperative MRI guidance is an accurate, reliable, cost-effective, and timesaving method for stereo-electroencephalography.

Moyamoya Vessel Pathology Imaged by Ultra–High-Field Magnetic Resonance Imaging at 7.0 T

Prompt diagnosis of vessel pathology and appropriate treatment of moyamoya vasculopathy (MMV) are essential to improve long-term prognosis. The aims of our study were to explore the diagnostic value of ultra-high-field (UHF) magnetic resonance imaging at 7.0 T in MMV patients and to compare the applicability of two different 7.0 T vessel imaging modalities to 3.0 T magnetic resonance angiography (MRA) and digital subtraction angiography (DSA). In a World Health Organization-registered and prospective imaging trial, patients were investigated at 7.0 T magnetization-prepared rapid-acquisition gradient echo (MPRAGE)-MRA and time-of-flight (TOF)-MRA, 3.0 T TOF-MRA, and by DSA. Six patients were included in our study and evaluated for MMV. 3.0 T TOF-MRA and 7.0 T MPRAGE-MRA were able to depict the complete major vascular tree and confirmed MMV-specific steno-occlusions of major intracranial arteries, as previously identified by DSA. 7.0 T TOF-MRA was limited to visualization of the circle of Willis as well as the internal carotid artery only. Donor vessels for bypass surgery (i.e., branches of superficial temporal artery) could be sufficiently visualized with all magnetic resonance modalities. Our results indicate that a specific 7.0 T vascular imaging protocol yields diagnostic information about vessel pathology in MMV that approximates conventional DSA. 7.0 T MPRAGE was superior to 7.0 T TOF-MRA due to shorter scanning times and better brain coverage. To date, however, limited availability of 7.0 T technology in medical facilities as well as technical and procedural constraints excludes a fair amount of patients from the clinical 7.0 T imaging process.

Cranial fixation plates in cerebral magnetic resonance imaging: a 3 and 7 Tesla in vivo image quality study.

This study assesses and quantifies impairment of postoperative magnetic resonance imaging (MRI) at 7 Tesla (T) after implantation of titanium cranial fixation plates (CFPs) for neurosurgical bone flap fixation. The study group comprised five patients who were intra-individually examined with 3 and 7 T MRI preoperatively and postoperatively (within 72h/3months) after implantation of CFPs. Acquired sequences included T1-weighted magnetization-prepared rapid-acquisition gradient-echo (MPRAGE), T2-weighted turbo-spin-echo (TSE) imaging, and susceptibility-weighted imaging (SWI). Two experienced neurosurgeons and a neuroradiologist rated image quality and the presence of artifacts in consensus reading. Minor artifacts occurred around the CFPs in MPRAGE and T2 TSE at both field strengths, with no significant differences between 3 and 7 T. In SWI, artifacts were accentuated in the early postoperative scans at both field strengths due to intracranial air and hemorrhagic remnants. After resorption, the brain tissue directly adjacent to skull bone could still be assessed. Image quality after 3months was equal to the preoperative examinations at 3 and 7 T. Image quality after CFP implantation was not significantly impaired in 7 T MRI, and artifacts were comparable to those in 3 T MRI.

Diffusion measurement of intraplaque hemorrhage and intramural hematoma using diffusion weighted MRI at 3T in cervical artery.

To assess the difference between carotid haemorrhagic plaque and non-haemorrhagic plaque by using diffusion-weighted imaging (DWI) and to evaluate carotid intraplaque haemorrhage (IPH) and intramural hematoma (IMH) of cervical artery dissection with apparent diffusion coefficient (ADC) measurement. Fifty-one symptomatic patients underwent 3.0-T carotid MR imaging, including conventional sequences, three-dimensional (3D) magnetization-prepared rapid acquisition gradient-echo (MPRAGE) sequence, and DWI. Thirty-nine patients with carotid plaque and eight patients with IMH of cervical artery dissection were finally included. The groups of hemorrhagic plaque, non-hemorrhagic plaque and IMH were divided according to 3D MPRAGE sequence. ADC values of different groups were measured, and t tests were performed. The mean ADC values of hemorrhagic plaques, non-hemorrhagic plaque and IMH were (1.284 ± 0.327) × 10(-3)mm(2)/s, (1.766 ± 0.477) × 10(-3)mm(2)/s, and (0.563 ± 0.119) × 10(-3)mm(2)/s, respectively. The mean ADC values of hemorrhagic and non-hemorrhagic regions in the hemorrhagic plaque group were (0.985 ± 0.376) × 10(-3)mm(2)/s and (1.480 ± 0.465) × 10(-3)mm(2)/s, respectively. The differences between the hemorrhagic plaque and non-hemorrhagic plaque, hemorrhagic region and non-hemorrhagic region in hemorrhagic plaque, and the hemorrhagic region in the hemorrhagic plaque and IMH of artery dissection were significant (P < 0.05). DWI may be a useful complement to conventional MR imaging for identifying haemorrhage of carotid plaques and differentiate IMHs from IPH. • ADC values of IPH are lower than the plaque without IPH. • DWI might be a useful complement to identify IPH. • IMH may be differentiated from IPH by using DWI.

Association of Cortical Lesion Burden on 7-T Magnetic Resonance Imaging With Cognition and Disability in Multiple Sclerosis.

Cortical lesions (CLs) contribute to physical and cognitive disability in multiple sclerosis (MS). Accurate methods for visualization of CLs are necessary for future clinical studies and therapeutic trials in MS. To evaluate the clinical relevance of measures of CL burden derived from high-field magnetic resonance imaging (MRI) in MS. An observational clinical imaging study was conducted at an academic MS center. Participants included 36 individuals with MS (30 relapsing-remitting, 6 secondary or primary progressive) and 15 healthy individuals serving as controls. The study was conducted from March 10, 2010, to November 23, 2012, and analysis was performed from June 1, 2011, to September 30, 2014. Seven-Tesla MRI of the brain was performed with 0.5-mm isotropic resolution magnetization-prepared rapid acquisition gradient echo (MPRAGE) and whole-brain, 3-dimensional, 1.0-mm isotropic resolution magnetization-prepared, fluid-attenuated inversion recovery (MPFLAIR). Cortical lesions, seen as hypointensities on MPRAGE, were manually segmented. Lesions were classified as leukocortical, intracortical, or subpial. Images were segmented using the Lesion-TOADS (Topology-Preserving Anatomical Segmentation) algorithm, and brain structure volumes and white matter (WM) lesion volume were reported. Volumes were normalized to intracranial volume. Physical disability was measured by the Expanded Disability Status Scale (EDSS). Cognitive disability was measured with the Minimal Assessment of Cognitive Function in MS battery. Cortical lesions were noted in 35 of 36 participants (97%), with a median of 16 lesions per participant (range, 0-99). Leukocortical lesion volume correlated with WM lesion volume (ρ = 0.50; P = .003) but not with cortical volume; subpial lesion volume inversely correlated with cortical volume (ρ = -0.36; P = .04) but not with WM lesion volume. Total CL count and volume, measured as median (range), were significantly increased in participants with EDSS scores of 5.0 or more vs those with scores less than 5.0 (count: 29 [11-99] vs 13 [0-51]; volume: 2.81 × 10-4 [1.30 × 10-4 to 7.90 × 10-4] vs 1.50 × 10-4 [0 to 1.01 × 10-3]) and in cognitively impaired vs unimpaired individuals (count: 21 [0-99] vs 13 [1-54]; volume: 3.51 × 10-4 [0 to 1.01 × 10-4] vs 1.19 × 10-4 [0 to 7.17 × 10-4]). Cortical lesion volume correlated with EDSS scores more robustly than did WM lesion volume (ρ = 0.59 vs 0.36). Increasing log[CL volume] conferred a 3-fold increase in the odds of cognitive impairment (odds ratio [OR], 3.36; 95% CI, 1.07-10.59; P = .04) after adjustment for age and sex and a 14-fold increase in odds after adjustment for WM lesion volume and atrophy (OR, 14.26; 95% CI, 1.06-192.37; P = .045). Leukocortical lesions had the greatest effect on cognition (OR for log [leukocortical lesion volume], 9.65; 95% CI, 1.70-54.59, P = .01). This study provides in vivo evidence that CLs are associated with cognitive and physical disability in MS and that leukocortical and subpial lesion subtypes have differing clinical relevance. Quantitative assessments of CL burden on high-field MRI may further our understanding of the development of disability and progression in MS and lead to more effective treatments.

Advanced MRI for carotid plaque imaging.

Atherosclerosis is the ubiquitous underling pathological process that manifests in heart attack and stroke, cumulating in the death of one in three North American adults. High-resolution magnetic resonance imaging (MRI) is able to delineate atherosclerotic plaque components and total plaque burden within the carotid arteries. Using dedicated hardware, high resolution images can be obtained. Combining pre- and post-contrast T1, T2, proton-density, and magnetization-prepared rapid acquisition gradient echo weighted fat-saturation imaging, plaque components can be defined. Post-processing software allows for semi- and fully automated quantitative analysis. Imaging correlation with surgical specimens suggests that this technique accurately differentiates plaque features. Total plaque burden and specific plaque components such as a thin fibrous cap, large fatty or necrotic core and intraplaque hemorrhage are accepted markers of neuroischemic events. Given the systemic nature of atherosclerosis, emerging science suggests that the presence of carotid plaque is also an indicator of coronary artery plaque burden, although the preliminary data primarily involves patients with stable coronary disease. While the availability and cost-effectiveness of MRI will ultimately be important determinants of whether carotid MRI is adopted clinically in cardiovascular risk assessment, the high accuracy and reliability of this technique suggests that it has potential as an imaging biomarker of future risk.

Transient Global Amnesia as a Presenting Manifestation of Cerebral Venous Thrombosis

Transient Global Amnesia as a Presenting Manifestation of Cerebral Venous Thrombosis

Distribution and features of middle cerebral artery atherosclerotic plaques in symptomatic patients: a 3.0 T high-resolution MRI study

Objectives:To investigate the distribution and features of middle cerebral artery (MCA) atherosclerotic plaques in patients with acute ischaemic strokes using high-resolution magnetic resonance (MR) imaging.Methods:Forty-six plaques from 44 MCAs (18 right and 26 left) in patients with acute symptomatic ischaemic strokes were studied. High-resolution MR imaging including tb1 weighted imaging (T1WI), tb2 weighted imaging (T2WI), PD weighted imaging (PDWI) and three-dimensional magnetization-prepared rapid acquisition gradient-echo (MPRAGE) sequences were used to visualise the plaques. The locations of plaques were classified into ventral, distal, superior and inferior wall of the MCA on oblique sagittal images. The thickness, area and signal intensities of plaques were recorded. The stenosis degree of MCA was calculated.Results:Among all 46 plaques, 26 plaques were located at the ventral wall (56.5%), 6 at the dorsal wall (13.0%), 9 at the superior wall (19.6%), and five at the inferior wall (10.9%). The average thickness and area of plaques were 1.37 ± 0.53 mm (range: 0.61–3.20 mm) and 3.80 ± 2.13 mm2 (range: 1.01–12.2 mm2), respectively. No significant differences in plaque thickness (P = 0.464), plaque area (P = 0.107) or stenosis degree (P = 0.563) were noted between different locations. Most of the plaques (44/46) showed iso-intensity on tbl1WI. On tbl2WI and PDWI, 24 plaques showed iso-intensity, 12 plaques showed a slightly high signal intensity (SI), and eight plaques showed a slightly low SI. Intraplaque haemorrhage was found in two plaques, with high SI on tbl1WI and MP-RAGE and high or mixed SI on tbl2WI and PDWI.Discussion:Middle cerebral artery plaques in patients with acute infarction have certain tendency to locate at ventral and superior walls. Distribution and features of plaques revealed some plaque formation characteristics and would help to understand underlying mechanisms of ischaemic events.

MRI-Based Measurement of Brain Stem Cross-Sectional Area in Relapsing-Remitting Multiple Sclerosis.

To determine if patients with relapsing-remitting multiple sclerosis (RRMS) have a reduced brain stem cross-sectional area (CSA) compared to age- and sex-matched controls. The brain stem is a common site of involvement in MS. However, relatively few imaging studies have investigated brain stem atrophy. Brain magnetic resonance imaging (MRI) was performed on patients and controls using a 1.5T MRI scanner with a quadrature head coil. Three-dimensional magnetization-prepared rapid acquisition gradient-echo (MPRAGE) images with 128 contiguous slices, covering the whole brain and brain stem and a T2-weighted image with3 mm transverse contiguous images were acquired. We measured the brain stem CSA at three sites, the midbrain, the pons, and the medulla oblongata in 35 RRMS patients and 35 controls using a semiautomated algorithm. CSA readings were normalized using the total external cranial volume to reduce normal population variance and increase statistical power. A significant CSA reduction was found in the midbrain (P ≤ .001), pons (P ≤ .001), and the medulla oblongata (P = .047) postnormalization. A CSA reduction of 9.3% was found in the midbrain, 8.7% in the pons, and 6.5% in the medulla oblongata. A significantly reduced, normalized brain stem CSA was detected in all areas of the brain stem of the RRMS patients, when compared to age- and gender-matched controls. Lack of detectable upper cervical cord atrophy in the same patients suggests some independence of the MS pathology in these regions.

Abstract 25: Carotid Plaque Thickness, Stenosis, Ulceration, Age And Male Sex Optimally Predict Carotid Intraplaque Hemorrhage

Background and Purpose: MRI-detected intraplaque hemorrhage (IPH) is associated with acute and future stroke. IPH can be detected with a high sensitivity, specificity and accuracy using heavily T1-weighted sequences such as the magnetization-prepared rapid acquisition gradient echo (MPRAGE) sequence. This sequence is not always available in screening of potential carotid sources of stroke. The purpose of this study was to determine the discriminatory power of clinical and imaging markers in predicting carotid IPH. Methods: In this retrospective cross sectional study, patients undergoing stroke workup were imaged with magnetic resonance imaging (MRI) and IPH detection. A total of 726 carotid plaques were imaged. Carotid imaging characteristics were recorded, including percent diameter and mm stenosis, plaque thickness, ulceration, intraluminal thrombus and IPH. Clinical confounders were recorded and a multivariable logistic regression model was fitted. Backward-elimination was used to determine essential predictors of IPH with a threshold two-sided p&lt;.10. Receiver operating characteristic (ROC) analysis was performed to determine discriminatory value. Results: Significant predictors of carotid IPH included plaque thickness (Odds ratio, OR=2.20, p&lt;.001), mm stenosis (OR=0.46, p&lt;.001), ulceration (OR=4.25, p=.020), age (OR=1.11, p=.001) and male sex (OR=3.23, p=.077). Percent diameter stenosis (OR=31.0, p=.001) could be used nearly interchangeably with mm stenosis. The final model discriminatory value was excellent (Area under the curve, AUC=0.932). This was significantly higher than models using only plaque thickness (AUC=0.881), only mm stenosis (AUC=0.830) or only ulceration (AUC=0.715) p&lt;.001. Conclusions: Optimal discrimination of carotid IPH required information on plaque thickness, mm stenosis, ulceration, age and male sex. When these factors are recorded, IPH can be predicted with a high discriminatory power.

Multiple sclerosis risk loci correlate with cervical cord atrophy and may explain the course of disability.

Genome-wide association studies (GWAS) underscore the genetic basis of multiple sclerosis (MS); however, only few of the newly reported genetic variations relevant in MS have been replicated or correlated for clinical/paraclinical phenotypes such as spinal cord atrophy in independent patient cohorts. We genotyped 141 MS patients for 58 variations reported to reach significance in GWAS. Expanded disability status scale (EDSS) and disease duration (DD) are available from regular clinical examinations. MRI included sagittal high-resolution 3D T1-weighted magnetization-prepared rapid acquisition gradient echo of the cervical cord region used for volumetry. Due dependency of mean upper cervical cord area (MUCCA) with EDSS and/or DD, correction operations were performed compensating for EDSS/DD. We assessed each MS risk locus for possible MUCCA association. We identified twelve risk loci that significantly correlated with MUCCA. For nine loci-BATF, CYP27B1, IL12B, NFKB1, IL7, PLEK, EVI5, TAGAP and nrs669607-patients revealed significantly higher degree of atrophy; TYK2, RGS1 and CLEC16A revealed inverse effects. The weighted genetic risk score over the twelve loci showed significant correlation with MUCCA. Our data reveal a risk gene depending paraclinical/clinical phenotype. Since MUCCA clearly correlates with disability, the candidates identified here may serve as prognostic markers for disability progression.

Multimodal navigated skull base tumor resection using image-based vascular and cranial nerve segmentation: A prospective pilot study.

Background:Skull base tumors frequently encase or invade adjacent normal neurovascular structures. For this reason, optimal tumor resection with incomplete knowledge of patient anatomy remains a challenge.Methods:To determine the accuracy and utility of image-based preoperative segmentation in skull base tumor resections, we performed a prospective study. Ten patients with skull base tumors underwent preoperative 3T magnetic resonance imaging, which included thin section three-dimensional (3D) space T2, 3D time of flight, and magnetization-prepared rapid acquisition gradient echo sequences. Imaging sequences were loaded in the neuronavigation system for segmentation and preoperative planning. Five different neurovascular landmarks were identified in each case and measured for accuracy using the neuronavigation system. Each segmented neurovascular element was validated by manual placement of the navigation probe, and errors of localization were measured.Results:Strong correspondence between image-based segmentation and microscopic view was found at the surface of the tumor and tumor-normal brain interfaces in all cases. The accuracy of the measurements was 0.45 ± 0.21 mm (mean ± standard deviation). This information reassured the surgeon and prevented vascular injury intraoperatively. Preoperative segmentation of the related cranial nerves was possible in 80% of cases and helped the surgeon localize involved cranial nerves in all cases.Conclusion:Image-based preoperative vascular and neural element segmentation with 3D reconstruction is highly informative preoperatively and could increase the vigilance of neurosurgeons for preventing neurovascular injury during skull base surgeries. Additionally, the accuracy found in this study is superior to previously reported measurements. This novel preliminary study is encouraging for future validation with larger numbers of patients.