High-resolution 3T Magnetic Resonance Imaging Research Articles

High-resolution 3T magnetic resonance imaging and histological analysis of capsuloligamentous complex of the first metatarsophalangeal joint

BackgroundThere are discrepancies in the understanding of the structure of the capsuloligamentous complex of the first metatarsophalangeal joint (MTPJ); this study aims to investigate the differences with previous anatomical reports of high-resolution 3T magnetic resonance imaging (MRI) and histological analysis in illustrating the structure of the capsuloligamentous complex of the first MTPJ.MethodsNine fresh frozen cadaveric feet specimens (from two women and three men; aged 32 to 58 years) were used in this study. All specimens underwent MR examination with T1-weighted imaging and T2-weighted spectral attenuated inversion recovery in three planes. Subsequently, all cadaveric feet specimens were sliced into 2-mm-thick sections. The MRI features of the capsuloligamentous complex of the first MTPJ were analyzed in these specimens. Hematoxylin–eosin and Masson’s trichrome staining methods were used to explore the histologic features of the capsuloligamentous complex of the first MTPJ.ResultsDifferent from most previous studies, our results showed that the plantar plate could be divided into four portions including the central portion of the plantar plate, the intersesamoid, the sesamoid phalangeal and the metatarsosesamoid ligaments. The normal central portion of the plantar plate could be clearly visualized in the sagittal and coronal plane MR images. The intersesamoid ligament is a continuation of the central portion of the plantar plate on the sagittal plane on the gross specimen, the MR imaging, and the histological examination. On the coronal plane of the gross specimen and MR imaging, the sesamoid phalangeal ligaments and the central portion of the plantar plate can be seen as separate ligaments, but they appeared interwoven with the same continuous collagenous fibers on the histological analysis.ConclusionHigh-resolution 3T MRI allows accurate demonstration of the different anatomical details of the capsuloligamentous complex of the first MTPJ from previous anatomical reports. The histological analysis provides further understanding of the structures of the capsuloligamentous complex of the first MTPJ from previous studies.

Validation of a multimodal algorithm for diagnosing giant cell arteritis with imaging

PurposeThe purpose of this study was to identify which combination of imaging modalities should be used to obtain the best diagnostic performance for the non-invasive diagnosis of giant cell arteritis (GCA). Materials and methodsThis IRB-approved prospective single-center study enrolled participants presenting with a suspected diagnosis of GCA from December 2014 to October 2017. Participants underwent high-resolution 3T magnetic resonance imaging (MRI), temporal and extra-cranial arteries ultrasound and retinal angiography (RA), prior to temporal artery biopsy (TAB). Diagnostic accuracy of each imaging modality alone, then a combination of several imaging modalities, was evaluated. Several algorithms were constructed to test optimal combinations using McNemar test. ResultsForty-five participants (24 women, 21 men) with mean age of 75.4 ± 16 (SD) years (range: 59–94 years) were enrolled; of these 43/45 (96%) had ophthalmological symptoms. Diagnosis of GCA was confirmed in 25/45 (56%) patients. Sensitivity and specificity of MRI, ultrasound and RA alone were 100% (25/25; 95% CI: 86–100) and 86% (19/22; 95% CI: 65–97), 88% (22/25; 95% CI: 69–97) and 84% (16/19; 95% CI: 60–97), 94% (15/16; 95% CI: 70–100) and 74% (14/19; 95% CI: 49–91), respectively. Sensitivity, specificity, positive predictive and negative predictive values ranged from 95 to 100% (95% CI: 77–100), 67 to 100% (95% CI: 38–100), 81 to 100% (95% CI: 61–100) and 91 to 100% (95% CI: 59–100) when combining several imaging tests, respectively. The diagnostic algorithm with the overall best diagnostic performance was the one starting with MRI, followed either by ultrasound or RA, yielding 100% sensitivity (22/22; 95% CI: 85–100%) 100% (15/15; 95% CI: 78–100) and 100% accuracy (37/37; 95% CI: 91–100). ConclusionThe use of MRI as the first imaging examination followed by either ultrasound or RA reaches high degrees of performance for the diagnosis of GCA and is recommended in daily practice.

Brain Structural Signature of RFC1-Related Disorder.

The cerebellar ataxia, neuropathy, and vestibular areflexia syndrome was initially described in the early 1990s as a late-onset slowly progressive condition. Its underlying genetic cause was recently mapped to the RFC1 gene, and additional reports have expanded on the phenotypic manifestations related to RFC1, although little is known about the pattern and extent of structural brain abnormalities in this condition. The aim is to characterize the structural signature of brain damage in RFC1-related disorder, correlating the findings with clinical symptoms and normal brain RFC1 expression. We recruited 22 individuals with molecular confirmation of RFC1 expansions and submitted them to high-resolution 3T magnetic resonance imaging scans. We performed multimodal analyses to assess separately cerebral and cerebellar abnormalities within gray and white matter (WM). The results were compared with a group of 22 age- and sex-matched controls. The mean age and disease duration of patients were 62.8 and 10.9 years, respectively. Ataxia, sensory neuronopathy, and vestibular areflexia were the most frequent manifestations, but parkinsonism and pyramidal signs were also noticed. We found that RFC1-related disorder is characterized by widespread and relatively symmetric cerebellar and basal ganglia atrophy. There is brainstem volumetric reduction along all its segments. Cerebral WM is also involved-mostly the corpus callosum and deep tracts, but cerebral cortical damage is rather restricted. This study adds new relevant insights into the pathophysiological mechanisms of RFC1-related disorder. It should no longer be considered a purely cerebellar and sensory pathway disorder. Basal ganglia and deep cerebral WM are additional targets of damage. © 2021 International Parkinson and Movement Disorder Society.

Title: IDENTIFYING THE AXILLARY NERVE DURING SHOULDER SURGERY: AN ANATOMIC STUDY USING ADVANCED IMAGING

Background:The axillary nerve (AXN) is one of the more commonly injured nerves during shoulder surgery. Prior anatomic studies of the AXN in adults were performed using cadaveric specimens with small sample sizes. Our research observes a larger cohort of magnetic resonance imaging (MRI) studies in order to gain a more representative sample of the course of the axillary nerve and aid surgeons intraoperatively.Methods:High-resolution 3T MRI studies performed at our institution from January 2010 to June 2019 were reviewed. Four blinded reviewers with musculoskeletal radiology or orthopaedic surgery training measured the distance of the AXN to the surgical neck of the humerus (SNH), the lateral tip of the acromion (LTA), and the inferior glenoid rim (IGR). Intra-class Correlation Coefficient (ICC) was calculated to assess reliability between reviewers. The nerve location was assessed relative to rotator cuff tear status.Results:A total of 257 shoulder MRIs were included. ICC was excellent at 0.80 for SNH, 0.90 for LTA and 0.94 for IGR. All intra-observer reliabilities were above 0.80. Mean distance from AXN to SNH was 1.7 cm (0.7-3.1 cm, IQR 1.38-2.00) and AXN to IGR was 1.6 cm (0.6-2.6 cm, IQR 1.33-1.88). The mean AXN to LTA distance was 7.1 cm, with a range of 5.2 to 9.0 cm across patient heights; there was a large effect size related to LTA to AXN distance and patient height with a correlation of r=0.603, (p<0.001). Rotator cuff pathology appears to affect nerve location by increasing the distance between AXN and SNH (p = 0.027).Discussion/Conclusion:The AXN is vulnerable to injury during both open and arthroscopic shoulder procedures. This injury can be either a result of direct trauma to the nerve or secondary to traction placed on the nerve with reconstructive procedures that distalize the humerus. Our study demonstrates that the axillary nerve can be found as little as 5.6 mm from IGR and 6.9 mm from the SNH. Additionally, we illustrate the relationship between patient height and LTA to AXN distance and complete rotator cuff tears and SNH to AXN distance. Our study is the first to demonstrate the nerve’s proximity to important surgical landmarks of the shoulder using a large sample size of high-resolution images in living human shoulders.Tables/Figures:Figure 1:.Example of measurements completed in each MRI study. Line A represents the distance between the lateral tip of the acromion process and the axillary nerve (LTA to AXN). Line B represents the distance between the inferior glenoid rim and the axillary nerve (IGR to AXN). Line C represents the distance between the surgical neck of the humerus and the axillary nerve (SNH to AXN). Average measurements derived from this study are labeled in parentheses.

Single-subject structural cortical networks in clinically isolated syndrome

Background: Structural cortical networks (SCNs) represent patterns of coordinated morphological modifications in cortical areas, and they present the advantage of being extracted from previously acquired clinical magnetic resonance imaging (MRI) scans. SCNs have shown pathophysiological changes in many brain disorders, including multiple sclerosis. Objective: To investigate alterations of SCNs at the individual level in patients with clinically isolated syndrome (CIS), thereby assessing their clinical relevance. Methods: We analyzed baseline data collected in a prospective multicenter (MAGNIMS) study. CIS patients (n = 60) and healthy controls (n = 38) underwent high-resolution 3T MRI. Measures of disability and cognitive processing were obtained for patients. Single-subject SCNs were extracted from brain 3D-T1 weighted sequences; global and local network parameters were computed. Results: Compared to healthy controls, CIS patients showed altered small-world topology, an efficient network organization combining dense local clustering with relatively few long-distance connections. These disruptions were worse for patients with higher lesion load and worse cognitive processing speed. Alterations of centrality measures and clustering of connections were observed in specific cortical areas in CIS patients when compared with healthy controls. Conclusion: Our study indicates that SCNs can be used to demonstrate clinically relevant alterations of connectivity in CIS.

Method for co-registration of high resolution 3Tmagnetic resonance imaging with standing 0.5T magnetic resonance imagingto investigate weight bearing joints

Method for co-registration of high resolution 3Tmagnetic resonance imaging with standing 0.5T magnetic resonance imagingto investigate weight bearing joints

Gray vs. White Matter Segmentation of the Conus Medullaris: Reliability and Variability in Healthy Volunteers

Magnetic resonance imaging (MRI)-derived spinal cord (SC) gray and white matter (GM/WM) volume are useful indirect measures of atrophy and neurodegeneration over time, typically obtained in the upper SC. Neuropathological evidence suggests that in certain neurological conditions, early degeneration may occur as low as the sacral SC. In this study, the feasibility of GM/WM segmentation of the conus medullaris (CM) was assessed in vivo. Twenty-three healthy volunteers (11 female, mean age 47 years) underwent high-resolution 3T MRI of the CM using a 3-dimensional fast field echo sequence. Reproducibility of the volume measurements was assessed in 5 subjects (2 female, 25-37 years) by one rater who repeated the analysis 3 times and also with 2 additional raters working independently in order to calculate the intra- and interrater coefficient of variation (COV), respectively. Furthermore, the influence of age, gender, spine and SC metrics on tissue-specific measures of the CM was investigated. Volumetric CM analyses (N = 23) for the SC, GM, and WM revealed a mean (SD) total volume of CM-TV = 1746.9 (296.7) mm3 , CM-GM-TV = 731.2 (106.0) mm3 , and CM-WM-TV = 1014.6 (211.3) mm3 , respectively. The intra-rater COV for measuring the CM-TV and CM-GM-TV was 3.38% and 7.42%, respectively; the interrater COV was 3.43% and 10.80%, respectively. Using age, gender, spine and SC metrics in regression models substantially reduced group variability for CM-TV, CM-WM-TV, and CM-GM-TV by up to 39.2%, 42.7%, and 21.2%, respectively. The results from this study demonstrate the feasibility of obtaining tissue-specific volume measurements in the CM by means of MRI with good reproducibility and provide normative data for future applications in neurological diseases affecting the lower SC.

Tract-Specific Volume Loss on 3T MRI in Patients With Cervical Spondylotic Myelopathy.

Case-control. The aim of this study was to understand the role of high-resolution magnetic resonance (MR) in identifying regional cord volume loss in cervical spondylotic myelopathy (CSM). Preliminary studies suggest that compression of the ventral region of the cord may contribute disproportionately to CSM symptomology; however, tract-specific data are lacking in the CSM population. The current study is the first to use 3T MR imaging (MRI) images of CSM patients to determine specific volume loss at the level of detail of individual descending white matter tracts. Twelve patients with CSM and 14 age-matched were enrolled prospectively and underwent 3-Tesla MRI of the cervical spine. Using the high-resolution images of the spinal cord, straightening and alignment with a template was performed and specific spinal cord tract volumes were measured using Spinal Cord Tool-box version 3.0.7. Modified Japanese orthopedic association (mJOA) and Nurick disability scores were collected in a prospective manner and were analyzed in relation to descending spinal tract volumes. Having CSM was predicted by anterior/posterior diameter, eccentricity of the cord [odds ratio (OR) 0.000000621, P = 0.004], ventral reticulospinal tract volume (OR 1.167, P = 0.063), lateral corticospinal tract volume (OR 1.034, P = 0.046), rubrospinal tract volume (OR 1.072, P = 0.011), and ventrolateral reticulospinal tract volume (OR 1.474, P = 0.005) on single variable logistic regression. Single variable linear regression showed decreases in anterior/posterior spinal cord diameter (P = 0.022), ventral reticulospinal tract volumes (P = 0.007), and ventrolateral reticulospinal tract volumes (P = 0.017) to significantly predict worsening mJOA scores. Similarly, decreases in ventral reticulospinal tract volumes significantly predicted increasing Nurick scores (P = 0.039). High-resolution 3T MRI can detect tract-specific volume loss in descending spinal cord tracts in CSM patients. Anterior/posterior spinal cord diameter, ventral reticulospinal tract, ventrolateral reticulospinal tract, lateral corticospinal tract, and rubrospinal tract volume loss are associated with CSM symptoms. 2.

Utility of additional dedicated high-resolution 3T MRI in children with medically refractory focal epilepsy

PurposeIn patients with medically refractory epilepsy and normal magnetic resonance imaging (MRI), high-resolution dedicated MRI may identify cryptic lesions. The aim of this study was to assess improvement in lesion detection and its impact on clinical management, using additional high-resolution dedicated 3T MRI in children with medically refractory epilepsy who had normal 3T epilepsy protocol MRI. Materials and methodsChildren who had resective epilepsy surgery and suspected focal cortical dysplasia (FCD) or normal 3T epilepsy protocol MRI were included. Those with other diagnosis on MRI including tumor and hippocampal sclerosis were excluded. Patients who had normal MRI on 3T epilepsy protocol underwent dedicated high-resolution 3T MRI through the epileptogenic zone, guided by video EEG, Magnetoencephalography and FDG-PET data. Results101 patients with at least 1 year follow-up were included. Twenty-nine of 44 (66%) patients who had normal epilepsy protocol MRI had a lesion identified on dedicated high-resolution MRI. The addition of dedicated high-resolution MRI to standard epilepsy protocol increased sensitivity from 53.1% (95%CI: 40%–66%) to 85.9% (95%CI: 75%–93%). Identified lesions were concordant to surgical resection in all patients and guided depth/strip electrode insertion in 20/25 (80%) patients who underwent staged resection. Dedicated MRI detected small deep seated lesions in 10/20 (50%), and guided depth electrodes placement, without which it would not be feasible, as the lobar location of epileptogenic zone from other non-invasive tests were not sufficiently precise. ConclusionPatients with non-lesional epilepsy on standard epilepsy protocol MR may benefit from high-resolution dedicated MRI to aid identification of an underlying lesion, which could impact surgical management and improve seizure control.

Sports Injury-Related Fingers and Thumb Deformity Due to Tendon or Ligament Rupture.

Background:Hand injuries are very common in sports, such as skiing and ball sports. One of the major reasons causing hand and finger deformity is due to ligament and tendon injury. The aim of this study was to investigate if the high-resolution 3T magnetic resonance imaging (MRI) can demonstrate the complex anatomy of the fingers and thumb, especially the tendons and ligaments, and provide the accurate diagnosis of clinically important fingers and thumbs deformity due to ligamentous and tendinous injuries during sport activities.Methods:Sixteen fresh un-embalmed cadaveric hands were harvested from eight cadavers. A total of 20 healthy volunteers' hands and 44 patients with fingers or thumb deformity due to sports-related injuries were included in this study. All subjects had MR examination with T1-weighted images and proton density-weighted imaging with fat suppression (PD FS) in axial, coronal, and sagittal plane, respectively. Subsequently, all 16 cadaveric hands were sliced into 2-mm thick slab with a band saw (six in coronal plane, six in sagittal plane, and four in axial plane). The correlation of anatomic sections and the MRI characteristics of tendons of fingers and the ulnar collateral ligament (UCL) at the metacarpal phalangeal joint (MCPJ) of thumb between 20 healthy volunteers and 44 patients (confirmed by surgery) were analyzed.Results:The normal ligaments and tendons in 16 cadaveric hands and 20 volunteers' hands showed uniform low-signal intensity on all the sequences of the MRI. Among 44 patients with tendinous and ligamentous injuries in the fingers or thumb, 12 cases with UCL injury at MCPJ of the thumb (Stener lesion = 8 and non-Stener lesion = 4), 6 cases with the central slip injury, 12 cases with terminal tendon injury, and 14 cases with flexor digitorum profundus injury. The ligaments and tendons disruption manifested as increased signal intensity and poor definition, discontinuity, and heterogeneous signal intensity of the involved ligaments and tendons.Conclusions:Sports injury-related fingers and thumb deformity are relatively common. MRI is an accurate method for evaluation of the anatomy and pathologic conditions of the fingers and thumb. It is a useful tool for accurate diagnosis of the sports-related ligaments and tendons injuries in hand.

High-resolution 3 T MRI of traumatic and degenerative triangular fibrocartilage complex (TFCC) abnormalities using Palmer and Outerbridge classifications

To investigate the usefulness of high-resolution 3T magnetic resonance imaging (MRI) for the evaluation of traumatic and degenerative triangular fibrocartilage complex (TFCC) abnormalities among three groups: patients presenting with wrist pain who were (a) younger than age 50 years or (b) age 50 or older (PT<50 and PT≥50, respectively), and (c) asymptomatic controls who were younger than age 50 years (AC). High-resolution 3T MRI was evaluated retrospectively in 96 patients, including 47 PT<50, 38 PT≥50, and 11 AC. Two board-certified radiologists reviewed the MRI images independently. MRI features of TFCC injury were analysed according to the Palmer classification, and cartilage degeneration around the TFCC was evaluated using the Outerbridge classification. Differences in MRI findings among these groups were detected using chi-square test. Cohen's kappa was calculated to assess interobserver and intra-observer reliability. The incidence of Palmer class 1A, 1C and 1D traumatic TFCC injury was significantly (p<0.05) higher in PT≥50 than in PT<50 (class 1A: 47.4% versus 27.7%, class 1C: 31.6% versus 12.8%, and class 1D: 21.1% versus 2.1%). Likewise, MRI findings of TFCC degeneration were observed more frequently in PT≥50 than in PT<50 (p<0.01). Outerbridge grade 2 or higher cartilage degeneration was significantly (p<0.01) more frequently seen in PT≥50 than in PT<50 (55.3% versus 17% in the lunate, 28.9% versus 4.3% in the triquetrum, 73.7% versus 12.8% in the ulna). High-resolution wrist MRI at 3T enables detailed evaluation of TFCC traumatic injury and degenerative changes using the Palmer and Outerbridge classifications, with good or excellent interobserver and intra-observer reliability.

High-resolution 3T Magnetic Resonance Imaging of the Triangular Fibrocartilage Complex in Chinese Wrists: Correlation with Cross-sectional Anatomy.

Background:The injury of the triangular fibrocartilage complex (TFCC) is a common cause of ulnar-sided wrist pain. The aim of this study was to investigate if the high-resolution 3T magnetic resonance imaging (MRI) could demonstrate the detailed complex anatomy of TFCC in Chinese.Methods:Fourteen Chinese cadaveric wrists (from four men and three women; age range at death from 30 to 60 years; mean age at 46 years) and forty healthy Chinese wrists (from 20 healthy volunteers, male/female: 10/10; age range from 21 to 53 years with a mean age of 32 years) in Beijing Jishuitan Hospital from March 2014 to March 2016 were included in this study. All cadavers and volunteers had magnetic resonance (MR) examination of the wrist with coronal T1-weighted and proton density-weighted imaging with fat suppression in three planes, respectively. MR arthrography (MRAr) was performed on one of the cadaveric wrists. Subsequently, all 14 cadaveric wrists were sliced into 2 mm thick slab with band saw (six in coronal plane, four in sagittal plane, and four in axial plane). The MRI features of normal TFCC were analyzed in these specimens and forty healthy wrists.Results:Triangular fibrocartilage, the ulnar collateral ligament, and the meniscal homolog could be best observed on images in coronal plane. The palmar and dorsal radioulnar ligaments were best evaluated in transverse plane. The ulnotriquetral and ulnolunate ligaments were best visualized in sagittal plane. The latter two structures and the volar and dorsal capsules were better demonstrated on MRAr.Conclusion:High-resolution 3T MRI is capable to show the detailed complex anatomy of the TFCC and can provide valuable information for the clinical diagnosis in Chinese.

High-Resolution 3T MR Imaging of the Triangular Fibrocartilage Complex.

This study is intended as a review of 3Tesla (T) magnetic resonance (MR) imaging of the triangular fibrocartilage complex (TFCC). The recent advances in MR imaging, which includes high field strength magnets, multi-channel coils, and isotropic 3-dimensional (3D) sequences have enabled the visualization of precise TFCC anatomy with high spatial and contrast resolution. In addition to the routine wrist protocol, there are specific techniques used to optimize 3T imaging of the wrist; including driven equilibrium sequence (DRIVE), parallel imaging, and 3D imaging. The coil choice for 3T imaging of the wrist depends on a number of variables, and the proper coil design selection is critical for high-resolution wrist imaging with high signal and contrast-to-noise ratio. The TFCC is a complex structure and is composed of the articular disc (disc proper), the triangular ligament, the dorsal and volar radioulnar ligaments, the meniscus homologue, the ulnar collateral ligament (UCL), the extensor carpi ulnaris (ECU) tendon sheath, and the ulnolunate and ulnotriquetral ligaments. The Palmer classification categorizes TFCC lesions as traumatic (type 1) or degenerative (type 2). In this review article, we present clinical high-resolution MR images of normal TFCC anatomy and TFCC injuries with this classification system.

Prognostic value of CA4/DG volumetry with 3 T magnetic resonance imaging on postoperative outcome of epilepsy patients with dentate gyrus pathology

Hippocampal sclerosis (HS), the most common feature of mesial temporal lobe epilepsy (MTLE), is widely accepted as surgical indication for refractory epilepsy. Pathological hallmarks in hippocampal dentate gyrus (DG), including granule cell loss (GCL) and granule cell dispersion (GCD), are known to be closely related to the status epilepticus and spontaneous seizure. Our aim was to assess the association between volumetric changes in the hippocampal CA4/DG determined with 3-Tesla (3T) magnetic resonance imaging (MRI) and the postoperative seizure outcomes in MTLE patients with or without dentate gyrus pathology (DGP). High-resolution T2- and T1-weighted three-dimensional (3D) MRI scans were performed on 39 MTLE patients before surgery with a 3T Philips scanner. ITK-SNAP software was used for segmentation and volumetry of the CA4/DG segment, and NASP software was used for 3D reconstructions of the CA4/DG region. Immunostaining for Neuronal Nuclei (NeuN) was performed on resected hippocampal specimens after surgery to verify the accuracy of CA4/DG segmentation and histopathological changes in DG. The CA4/DG subfield could be precisely segmented with high-resolution 3T MRI and confirmed by comparison of NeuN-immunoreactive slices with MRI results. MTLE patients with DGP showed smaller CA4/DG volume and favorable postoperative seizure outcomes. The volumetry of CA4/DG was associated with the pathological changes in DG in MTLE patients. The volumetry of CA4/DG with preoperative 3T MRI could predict the postoperative seizure outcomes in those patients.

MP2RAGE provides new clinically-compatible correlates of mild cognitive deficits in relapsing-remitting multiple sclerosis.

Despite that cognitive impairment is a known early feature present in multiple sclerosis (MS) patients, the biological substrate of cognitive deficits in MS remains elusive. In this study, we assessed whether T1 relaxometry, as obtained in clinically acceptable scan times by the recent Magnetization Prepared 2 Rapid Acquisition Gradient Echoes (MP2RAGE) sequence, may help identifying the structural correlate of cognitive deficits in relapsing-remitting MS patients (RRMS). Twenty-nine healthy controls (HC) and forty-nine RRMS patients underwent high-resolution 3T magnetic resonance imaging to obtain optimal cortical lesion (CL) and white matter lesion (WML) count/volume and T1 relaxation times. T1 z scores were then obtained between T1 relaxation times in lesion and the corresponding HC tissue. Patient cognitive performance was tested using the Brief Repeatable Battery of Neuro-psychological Tests. Multivariate analysis was applied to assess the contribution of MRI variables (T1 z scores, lesion count/volume) to cognition in patients and Bonferroni correction was applied for multiple comparison. T1 z scores were higher in WML (p < 0.001) and CL-I (p < 0.01) than in the corresponding normal-appearing tissue in patients, indicating relative microstructural loss. (1) T1 z scores in CL-I (p = 0.01) and the number of CL-II (p = 0.04) were predictors of long-term memory; (2) T1 z scores in CL-I (β = 0.3; p = 0.03) were independent determinants of long-term memory storage, and (3) lesion volume did not significantly influenced cognitive performances in patients. Our study supports evidence that T1 relaxometry from MP2RAGE provides information about microstructural properties in CL and WML and improves correlation with cognition in RRMS patients, compared to conventional measures of disease burden.

A novel in vivo atlas of human hippocampal subfields using high-resolution 3T magnetic resonance imaging

The hippocampus is a neuroanatomical structure that has been widely studied in the context of learning, memory, stress, and neurodegeneration. Neuroanatomically, the hippocampus is subdivided into several subfields with intricate morphologies and complex three-dimensional relationships. Recent studies have demonstrated that the identification of different subfields is possible with high-resolution and -contrast image volumes acquired using ex vivo specimens in a small bore 9.4 T scanner and, more recently, in vivo, at 7 T. In these studies, the neuroanatomical definitions of boundaries between subfields are based upon salient differences in image contrast. Typically, the definition of subfields has not been possible using commonly available magnetic resonance (MR) scanners (i.e.: 1.5 or 3T) due to resolution and contrast limitations. To overcome the limited availability of post-mortem specimens and expertise in state-of-the-art high-field imaging, we propose a coupling of MR acquisition and detailed segmentation techniques that allow for the reliable identification of hippocampal anatomy (including subfields). High-resolution and -contrast T1- and T2-weighted image volumes were acquired from 5 volunteers (2 male; 3 female; age range: 29-57, avg. 37) using a clinical research-grade 3T scanner and have final super-sampled isotropic voxel dimensions of 0.3mm. We demonstrate that by using these acquisition techniques, our data results in contrast-to-noise ratios that compare well with high-resolution images acquired with long scan times using post-mortem data at higher field strengths. For the subfields, the cornus ammonis (CA) 1, CA2/CA3, CA4/dentate gyrus, stratum radiatum/stratum lacunosum/stratum moleculare, and subiculum were all labeled as separate structures. Hippocampal volumes are reported for each of the substructures and the hippocampus as a whole (range for hippocampus: 2456.72-3325.02 mm(3)). Intra-rater reliability of our manual segmentation protocol demonstrates high reliability for the whole hippocampus (mean Dice Kappa of 0.91; range 0.90-0.92) and for each of the subfields (range of Dice Kappas: 0.64-0.83). We demonstrate that our reliability is better than the Dice Kappas produced by simulating the following errors: a translation by a single voxel in all cardinal directions and 1% volumetric shrinkage and expansion. The completed hippocampal atlases are available freely online (info2.camh.net/kf-tigr/index.php/Hippocampus) and can be coupled with novel computational neuroanatomy techniques that will allow for them to be customized to the unique neuroanatomy of different subjects, and ultimately be utilized in different analysis pipelines.

Focal cortical damage parallels cognitive impairment in minimal hepatic encephalopathy

Little attention has been paid to cortical integrity in patients with minimal hepatic encephalopathy (MHE), although cognitive functions affected in early stages of liver disease are mainly allocated in different neocortical structures. Here we used cortical surface-based analysis techniques to investigate if patterns of cortical thinning accompany the mildest form of HE. To aim this goal, cortical thickness obtained from high-resolution 3T magnetic resonance imaging (MRI) was measured in patients with no MHE (NMHE), MHE, and healthy controls. Further correlation analyses were performed to examine whether scores in the critical flicker frequency (CFF) test, and blood ammonia levels accounted for the loss of cortical integrity in different stages of liver disease. Finally, we assessed group differences in volume of different subcortical regions and their potential relationships with CFF scores/blood ammonia levels. Results showed a focal thinning of the superior temporal cortex and precuneus in MHE patients when compared with NMHE and controls. Relationships between blood ammonia levels and cortical thickness of the calcarine sulcus accounted for impaired visual judgment in patients with MHE when compared to NMHE. Regression analyses between cortical thickness and CFF predicted differences between controls and the two groups of HE patients, but failed to discriminate between patients with NMHE and MHE. Taking together, these findings provide the first report of cortical thinning in MHE patients, and they yield novel insights into the neurobiological basis of cognitive impairment associated with early stages of liver diseases.

Diffusion tensor imaging in Alzheimer's disease and dementia with Lewy bodies

White matter changes have been investigated in Alzheimer's disease (AD) in a number of studies using diffusion imaging. Fewer studies have investigated dementia with Lewy bodies (DLB). We used diffusion-weighted magnetic resonance imaging (MRI) and high-resolution (0.3 mm in-plane) coronal 3T MRI of the medial temporal lobe in 16 subjects with AD, 16 with DLB and 16 similarly aged healthy subjects. We found increased mean diffusivity in the temporal lobe of AD, and reduced fractional anisotropy (FA) in a small cluster in the right postcentral gyrus region in the DLB group. Mean FA in this cluster correlated with UPDRS (Unified Parkinson's Disease Rating Scale) motor score. We had previously reported reduced visibility in the AD group of a dark appearing layer of the hippocampus in the high-resolution images. In an SPM analysis on all subjects, there were significant clusters of reduced FA in the corpus callosum, fornix and stria terminalis that correlated with the visual rating of the hippocampus. These results suggest that changes to the hippocampus are associated with structural changes to the white matter fibres of the hippocampus output, and that changes in motor function are associated with changes in white matter underlying somatosensory cortex.

Visualization of Vascular Compression of the Trigeminal Nerve With High-Resolution 3T MRI: A Prospective Study Comparing Preoperative Imaging Analysis to Surgical Findings in 40 Consecutive Patients Who Underwent Microvascular Decompression for Trigeminal Neuralgia

High-resolution three-dimensional (3D) magnetic resonance imaging (MRI) has demonstrated its ability to predict fine trigeminal neurovascular anatomy. To address the predictive value of 3-Tesla (3T) MRI in detecting and assessing features of neurovascular compression (NVC), particularly regarding the degree of compression exerted on the root, in patients who underwent microvascular decompression (MVD) for classic primary trigeminal neuralgia. This prospective study includes 40 consecutive patients who underwent MVD for classic primary trigeminal neuralgia. All patients underwent a preoperative 3T MRI with 3D T2-weighted driven equilibrium (DRIVE), 3D time-of-flight (TOF) magnetic resonance angiography (MRA), and 3D T1-weighted gadolinium-enhanced sequences in combination. Evaluations were performed by 2 independent observers and compared with the operative findings. For prediction of NVC, image analysis corresponded with surgical findings in 39 cases. Of the 3 patients in whom image analysis did not show NVC, 2 did not have NVC at the time of intraoperative observation. MRI sensitivity was 97.4% (37/38), and specificity was 100% (2/2). The kappa coefficients (κ) for predicting the offending vessel, its location, and the site of compression were 0.882, 0.813, and 0.942, respectively. Image analysis correctly defined the severity of the compression in 31 of the 37 cases. The κ coefficients predicting the degree of compression were 0.813, 0.833, and 0.852, respectively, for Grades 1 (simple contact), 2 (distortion), and 3 (marked indentation). 3T MRI using 3D T2-weighted DRIVE in combination with 3D TOF-MRA and 3D T1-weighted gadolinium-enhanced sequences proved to be reliable in detecting NVC and in predicting the degree of root compression, the outcome being correlated with the latter.

Reduced Posterior Hippocampal Volume in Posttraumatic Stress Disorder

Hippocampal volume is reduced in posttraumatic stress disorder (PTSD). In the present study, we sought to determine whether volume loss is homogenously distributed or confined to a certain part of the structure. Twenty-two adult outpatients with PTSD (11 after prolonged prepubertal trauma and 11 after single adult trauma) and 22 matched healthy subjects were scanned at the National Institute of Mental Health using high-resolution 3T magnetic resonance imaging between September 2003 and August 2004. PTSD diagnosis was conferred using the Structured Clinical Interview for DSM-IV. Volumes of whole, anterior, and posterior hippocampus and subiculum were compared between groups. Total hippocampal volume was lower in patients with PTSD (p = .02), with a significant diagnosis by hippocampal-subregion interaction (p = .02). Post hoc analysis revealed significantly smaller posterior hippocampi in PTSD (p = .006), with no difference in the volumes of anterior hippocampus or subiculum. No volume differences were found between PTSD participants with prolonged childhood abuse compared to single adult trauma exposure. The posterior hippocampus has been associated with storage, processing, and retrieval of spatiotemporal memories, central to the protective function of fear conditioning. Volume deficit in the posterior hippocampus may indicate malfunction in this faculty, leading to the exaggerated conditioned fear response observed in PTSD.