Magnetization-prepared Rapid Acquisition Gradient Echo Research Articles

Method for simultaneous voxel‐based morphometry of the brain and cervical spinal cord area measurements using 3D‐MDEFT

PurposeTo investigate whether a 3D-modified driven equilibrium Fourier transform (MDEFT)-based acquisition protocol established for brain morphometry also yields reliable information about the cross-sectional spinal cord area (SCA).Materials and MethodsImages of brain and cervical cord of 10 controls and eight subjects with spinal cord injury (SCI) were acquired with the 3D-MDEFT-based imaging protocol and an 8-channel receive head coil. The new protocol was validated by two observers 1) comparing the SCA measured with the standard acquisition protocol (3D magnetization-prepared rapid acquisition gradient echo [MPRAGE] and dedicated spine coil) and the new protocol; and 2) determining the scan–rescan reproducibility of the new protocol.ResultsScan–rescan reproducibility of SCA measurements with the MDEFT approach showed a similar precision for both observers with standard deviation (SD) <4.5 mm2 and coefficient of variation (CV) ≤5.1%. Analysis of variance (ANOVA) revealed a main effect of observer and interaction between observer and scan protocol that could be primarily attributed to a small observer bias for MPRAGE (difference in SCA <2.1 mm2). No bias was observed for 3D-MDEFT vs. 3D-MPRAGE.ConclusionThe 3D-MDEFT method allows for robust unbiased assessment of SCA in addition to brain morphology. J. Magn. Reson. Imaging 2010;32:1242–1247. © 2010 Wiley-Liss, Inc.

Improved carotid intraplaque hemorrhage imaging using a slab‐selective phase‐sensitive inversion‐recovery (SPI) sequence

Intraplaque hemorrhage in atherosclerotic plaques has been associated with accelerated plaque growth as well as exacerbation of clinical symptoms. The identification of intraplaque hemorrhage using magnetic resonance imaging primarily relies on the detection of methemoglobin on T(1) weighted images. Current techniques are limited by insufficient intraplaque hemorrhage-wall contrast and poor blood suppression. In this study, a slab-selective phase-sensitive inversion-recovery (SPI) technique is proposed by combining a phase-sensitive reconstruction with a T(1) weighted sequence specifically designed to achieve improved intraplaque hemorrhage imaging. The SPI sequence was optimized and then used on ex vivo plaque specimens for histology based validation and intraplaque hemorrhage-wall contrast-to-noise ratio comparison with magnetization-prepared 3D rapid acquisition gradient echo MP-RAGE. SPI and MP-RAGE were also tested on a group of atherosclerosis patients to compare in vivo intraplaque hemorrhage-wall contrast-to-noise ratio and blood suppression effectiveness. On ex vivo specimens SPI had better intraplaque hemorrhage identification accuracy and a significantly higher intraplaque hemorrhage-wall contrast-to-noise ratio (P = 0.01) than MP-RAGE. Similar results were found in the in vivo test: Slab-selective phase-sensitive inversion-recovery provided a significantly improved intraplaque hemorrhage-wall contrast-to-noise ratio (P < 0.01) and blood suppression efficiency (P < 0.01). In conclusion, SPI is a novel technique optimized for intraplaque hemorrhage detection and validated against histology. It has demonstrated its capability for improved in vivo intraplaque hemorrhage identification and blood suppression in atherosclerosis patients.

Structural changes in the hippocampus in major depressive disorder: contributions of disease and treatment

Previous magnetic resonance imaging (MRI) studies of patients with major depressive disorder (MDD) have consistently shown bilateral and unilateral reductions in hippocampal volume relative to healthy controls. Recent structural MRI studies have addressed the question of whether changes in the volume of hippocampal subregions may be associated with MDD. We used a comprehensive and reliable 3-dimensional tracing protocol that enables delineation of hippocampal subregions (head, body, tail) to study changes in the hippocampus of patients with MDD. We recruited 39 MDD patients (16 medicated, 23 unmedicated) and 34 healthy age- and sex-matched controls. We acquired images using a magnetization-prepared rapid acquisition gradient echo sequence on a 1.5-T scanner with a spatial resolution of 1.5 mm x 0.5 mm x 0.5 mm. We performed volumetric analyses, blinded to diagnosis, using the interactive software package Display. All volumes were adjusted for intracranial volume. We found a significant reduction in the volume of the hippocampal tail bilaterally, right hippocampal head and right total hippocampus in MDD patients. Medicated MDD patients showed increased hippocampal body volume compared with both healthy controls and unmedicated patients. This study was cross-sectional. Further prospective studies are needed to determine the direct effect of antidepressant treatment. Our results suggest that decreased hippocampal tail and hippocampal head volumes could be trait changes, whereas hippocampal body changes may be dependent on treatment. We showed that long-term antidepressant treatment may affect hippocampal volume in patients with MDD.

Improved Detection of Active Multiple Sclerosis Lesions: 3D Subtraction Imaging

To examine the benefits of using near-isotropic single-slab three-dimensional (3D) magnetic resonance (MR) imaging for the creation of subtraction images and to evaluate their performance in the detection of active multiple sclerosis (MS) brain lesions in comparison with two-dimensional (2D) subtraction images. The study protocol was approved by the local ethics review board and all subjects gave written informed consent before investigation. Three-dimensional MR sequences, including double inversion-recovery, fluid-attenuated inversion recovery, T2-weighted, and T1-weighted magnetization-prepared rapid acquisition gradient-echo (MP-RAGE), and corresponding 2D sequences were performed twice in 14 patients (eight women, six men; mean age, 37.6 years) with MS and nine age-matched healthy control subjects (three women, six men; mean age, 31.7 years). Active lesions were scored by two independent raters, followed by a consensus reading. Lesion counts were evaluated by using negative binomial regression; interrater agreement was evaluated by using intraclass correlation coefficient. Three-dimensional subtraction images had less residual misregistration and flow artifacts and depicted higher numbers of active lesions with greater interobserver agreement compared with 2D subtraction images. Among the 3D sequences, MP-RAGE subtraction imaging enabled detection of a significantly higher mean number of positive active MS lesions compared with 2D subtraction imaging (2.8 versus 1.7, P = .012), particularly infratentorial lesions (0.6 vs 0.1, P < .05), and a substantially higher (nonsignificant) mean number of small (<3 mm) lesions (0.6 vs 0.1, P > .05). Three-dimensional subtraction imaging, after image registration, produced better image quality, leading to increased detection of active MS lesions with greater interobserver agreement in comparison with 2D subtraction imaging; 3D MP-RAGE subtraction imaging represents a promising technique to increase sensitivity in ascertaining lesion dissemination in time and increase the power of MR imaging metrics for the evaluation of treatment effects in clinical trials.

Carotid Intraplaque Hemorrhage Imaging at 3.0-T MR Imaging: Comparison of the Diagnostic Performance of Three T1-weighted Sequences

To compare the diagnostic performances of three T1-weighted 3.0-T magnetic resonance (MR) sequences at carotid intraplaque hemorrhage (IPH) imaging, with histo logic analysis as the reference standard. Institutional review board approval and informed consent were obtained for this HIPAA-compliant study. Twenty patients scheduled for carotid endarterectomy underwent 3.0-T carotid MR imaging, including two-dimensional fast spin-echo, three-dimensional time-of-flight (TOF), and three-dimensional magnetization-prepared rapid acquisition gradient-echo (RAGE) sequences. Two reviewers blinded to the histologic findings assessed the presence, area, and signal intensity of IPH with each sequence. Detection statistics (sensitivity, specificity, and Cohen kappa values) and agreement between area measurements (Pearson correlation coefficient [r] values) were calculated for each sequence. When all 231 available MR sections were included for analysis, the magnetization-prepared RAGE (kappa = 0.53) and fast spin-echo (kappa = 0.42) sequences yielded moderate agreement between MR and histologic measurements, while the TOF sequence yielded fair agreement (k = 0.33). However, when 47 sections with either small IPHs or heavily calcified IPHs were excluded, sensitivity, specificity, and kappa values, respectively, were 80%, 97%, and 0.80 for magnetization-prepared RAGE imaging; 70%, 92%, and 0.63 for fast spin-echo imaging; and 56%, 96%, and 0.57 for TOF imaging. MR imaging-histologic analysis correlation for IPH area was highest with magnetization-prepared RAGE imaging (r = 0.813), followed by TOF (r = 0.745) and fast spin-echo (r = 0.497) imaging. The capability of these three sequences for IPH detection appeared to be in good agreement with the quantitative contrast of IPH versus background plaque tissue. The magnetization-prepared RAGE sequence, as compared with the fast spin-echo and TOF sequences, demonstrated higher diagnostic capability for the detection and quantification of IPH. Potential limitations of 3.0-T IPH MR imaging are related to hemorrhage size and coexisting calcification.

Scan‐rescan reproducibility of carotid atherosclerotic plaque morphology and tissue composition measurements using multicontrast MRI at 3T

To evaluate interscan reproducibility of both vessel morphology and tissue composition measurements of carotid atherosclerosis using a fast, optimized, 3T multicontrast protocol. A total of 20 patients with carotid stenosis >15% identified by duplex ultrasound were recruited for two independent 3T MRI (Philips) scans within one month. A multicontrast protocol including five MR sequences was applied: TOF, T1-/T2-/PD-weighted and magnetization-prepared rapid acquisition gradient-echo (MP-RAGE). Carotid artery morphology (wall volume, lumen volume, total vessel volume, normalized wall index, and mean/maximum wall thickness) and plaque component size (lipid rich/necrotic core, calcification, and hemorrhage) were measured over two time points. After exclusion of images with poor image quality, 257 matched locations from 18 subjects were available for analysis. For the quantitative carotid morphology measurements, coefficient of variation (CV) ranged from 2% to 15% and intraclass correlation coefficient (ICC) ranged from 0.87 to 0.99. Except for maximum wall thickness (ICC = 0.87), all ICC were larger than 0.90. For the quantitative plaque composition measurements, the ICC of the volume and relative content of lipid rich/necrotic core and calcification were larger than 0.90 with CV ranging from 22% to 32%. The results from the multicontrast high-resolution 3T MR study show high reliability for carotid morphology and plaque component measurements. 3T MRI is a reliable tool for longitudinal clinical trials, with shorter scan time compared to 1.5T.

Multi-Contrast, Isotropic, Single-Slab 3D MR Imaging in Multiple Sclerosis

To describe signal and contrast properties of an isotropic, single-slab 3D dataset [double inversion-recovery (DIR), fluid-attenuated inversion recovery (FLAIR), T2, and T1-weighted magnetization prepared rapid acquisition gradient-echo (MPRAGE)] and to evaluate its performance in detecting multiple sclerosis (MS) brain lesions compared to 2D T2-weighted spin-echo (T2SE). All single-slab 3D sequences and 2D-T2SE were acquired in 16 MS patients and 9 age-matched healthy controls. Lesions were scored independently by two raters and characterized anatomically. Two-tailed Bonferroni-corrected Student's t-tests were used to detect differences in lesion detection between the various sequences per anatomical area after log-transformation. In general, signal and contrast properties of the 3D sequences enabled improved detection of MS brain lesions compared to 2D-T2SE. Specifically, 3D-DIR showed the highest detection of intracortical and mixed WM-GM lesions, whereas 3D-FLAIR showed the highest total number of WM lesions. Both 3D-DIR and 3D-FLAIR showed the highest number of infratentorial lesions. 3D-T2 and 3D-MPRAGE did not improve lesion detection compared to 2D-T2SE. Multi-contrast, isotropic, single-slab 3D MRI allowed an improved detection of both GM and WM lesions compared to 2D-T2SE. A selection of single-slab 3D contrasts, for example, 3D-FLAIR and 3D-DIR, could replace 2D sequences in the radiological practice.

Reduced prefrontal and orbitofrontal gray matter in female adolescents with borderline personality disorder: Is it disorder specific?

There is evidence that adults with borderline personality disorder (BPD) are characterized by abnormalities in frontolimbic brain areas. In this study we aimed to determine whether brain volume alterations already exist in adolescents with BPD. Sixty female right-handed individuals (age range, 14–18 years), 20 with a DSM-IV diagnosis of borderline personality disorder, 20 patients with a DSM-IV defined current psychiatric disorder and 20 healthy control subjects were included. Groups were matched for age and IQ. Using a 3 T MRI scanner, we collected 1 mm axial sections using a three-dimensional sagittal isotropic Magnetization Prepared Rapid Acquisition Gradient Echo (MPRAGE) sequence. Images were analyzed using voxel-based morphometry (VBM). Voxel-based analysis revealed that adolescents with BPD showed reduced gray matter in the dorsolateral cortex (DLPFC) bilaterally and in the left orbitofrontal cortex (OFC) relative to healthy control subjects. Adolescent clinical control subjects displayed significantly decreased gray matter volume in the right DLPFC in comparison with healthy control subjects. No significant gray matter differences were detected between the BPD group and the clinical control group. No group differences were found in the limbic system or in any white matter structures. The present study indicates that the early morphological changes in BPD are located in the PFC. However, these changes may not be BPD specific since similar changes were found in the clinical control group. Changes in limbic brain volumes and white matter structures might occur over the course of the illness.

Minimally invasive superficial temporal artery to middle cerebral artery bypass through a minicraniotomy: benefit of three-dimensional virtual reality planning using magnetic resonance angiography

The aim of the authors in this study was to introduce a minimally invasive superficial temporal artery to middle cerebral artery (STA-MCA) bypass surgery by the preselection of appropriate donor and recipient branches in a 3D virtual reality setting based on 3-T MR angiography data. An STA-MCA anastomosis was performed in each of 5 patients. Before surgery, 3-T MR imaging was performed with 3D magnetization-prepared rapid acquisition gradient echo sequences, and a high-resolution CT 3D dataset was obtained. Image fusion and the construction of a 3D virtual reality model of each patient were completed. In the 3D virtual reality setting, the skin surface, skull surface, and extra- and intracranial arteries as well as the cortical brain surface could be displayed in detail. The surgical approach was successfully visualized in virtual reality. The anatomical relationship of structures of interest could be evaluated based on different values of translucency in all cases. The closest point of the appropriate donor branch of the STA and the most suitable recipient M(3) or M(4) segment could be calculated with high accuracy preoperatively and determined as the center point of the following minicraniotomy. Localization of the craniotomy and the skin incision on top of the STA branch was calculated with the system, and these data were transferred onto the patient's skin before surgery. In all cases the preselected arteries could be found intraoperatively in exact agreement with the preoperative planning data. Successful extracranial-intracranial bypass surgery was achieved without stereotactic neuronavigation via a preselected minimally invasive approach in all cases. Subsequent enlargement of the craniotomy was not necessary. Perioperative complications were not observed. All bypasses remained patent on follow-up. With the application of a 3D virtual reality planning system, the extent of skin incision and tissue trauma as well as the size of the bone flap was minimal. The closest point of the appropriate donor branch of the STA and the most suitable recipient M(3) or M(4) segment could be preoperatively determined with high accuracy so that the STA-MCA bypass could be safely and effectively performed through an optimally located minicraniotomy with a mean diameter of 22 mm without the need for stereotactic guidance.

Multisequence-imaging protocols to detect cortical lesions of patients with multiple sclerosis: Observations from a post-mortem 3 Tesla imaging study

Neocortical lesions (NLs) are an important component of multiple sclerosis (MS) pathology and may account for part of the physical and cognitive disability. Visualizing NLs of patients with MS using magnetic resonance imaging (MRI) poses several significant challenges. We optimized the inversion time (TI) of T 1-based magnetization-prepared rapid acquisition gradient-echo (MPRAGE) images by suppressing the signal of the lesions and enhancing their appearance as hypointensities, on the basis of the derived quantitative T 1 measurements. The latter were achieved by the means of 2D inversion recovery fast spin echo (IR-FSE), repeated using different inversion times (TI). Comparisons of detection of NLs by MPRAGE and dual echo T 2 weighted (T 2W) and proton density (PD) W. Four coronal brain slices from a deceased MS patient and two coronal brain slices from two formerly healthy donors were imaged using a 3 Tesla magnet (3 T) equipped with a multi-channel coil. Based upon the averaged T1 values computed from the MS specimen as well as visual inspection, an optimal TI of 380 ms was selected for the MPRAGE image. No NLs were seen in the specimens of the two healthy donors. Of the 40 total NLs observed, 8 (20%) were visible in all three sequences employed. Three (7.5%) NLs were visible only in the PDW image and 5 (12.5%) were seen only in the T 2W image. Four NLs (10%) had clearly unique conspicuity in the MPRAGE image. Of those, 3 were retrospectively scored in the PDW image (1 NL) or in the T2W image (2 NLs). We conclude that for the detection of MS-related NLs, high-resolution T 1-based MPRAGE and T 2-W images offer complementary information and the combination of the two image sequences is crucial for increasing the sensitivity of detecting MS-induced NLs.

Usefulness of Contrast-Enhanced T1-Weighted Sampling Perfection with Application-Optimized Contrasts by Using Different Flip Angle Evolutions in Detection of Small Brain Metastasis at 3T MR Imaging: Comparison with Magnetization-Prepared Rapid Acquisition of Gradient Echo Imaging

Early accurate diagnosis of brain metastases is crucial for a patient's prognosis. This study aimed to compare the conspicuity and detectability of small brain metastases between contrast-enhanced 3D fast spin-echo (sampling perfection with application-optimized contrasts by using different flip angle evolutions [SPACE]) and 3D gradient-echo (GE) T1-weighted (magnetization-prepared rapid acquisition of GE [MPRAGE]) images at 3T. Sixty-nine consecutive patients with suspected brain metastases were evaluated prospectively by using SPACE and MPRAGE on a 3T MR imaging system. After careful evaluation by 2 experienced neuroradiologists, 92 lesions from 16 patients were selected as brain metastases. We compared the shorter diameter, contrast rate (CR), and contrast-to-noise ratio (CNR) of each lesion. Diagnostic ability was compared by using receiver operating characteristic (ROC) analysis. Ten radiologists (5 neuroradiologists and 5 residents) participated in the reading. The mean diameter was significantly larger by using SPACE than MPRAGE (mean, 4.5 +/- 3.7 versus 4.3 +/- 3.7 mm, P = .0014). The CR and CNR of SPACE (mean, 57.3 +/- 47.4%, 3.0 +/- 1.9, respectively) were significantly higher than those of MPRAGE (mean, 37.9 +/- 41.2%, 2.6 +/- 2.2; P < .0001, P = .04). The mean area under the ROC curve was significantly larger with SPACE than with MPRAGE (neuroradiologists, 0.99 versus 0.88, P = .013; residents, 0.99 versus 0.78, P = .0001). Lesion detectability was significantly higher on SPACE than on MPRAGE, irrespective of the experience of the reader in neuroradiology. SPACE should be a promising diagnostic technique for assessing brain metastases.

Reduced Gray Matter Volume in the Frontotemporal Cortex of Patients with Early Subacute Sclerosing Panencephalitis

Subacute sclerosing panencephalitis (SSPE) is a persistent infection of the central nervous system by the measles virus. Patients in the initial stages of SSPE show behavioral symptoms and usually normal cranial MR imaging findings. We aimed to investigate the gray matter volume changes in patients with early SSPE. Seventeen patients with SSPE with normal cranial MR imaging findings and 30 sex- and age-matched control subjects were included in the study. Clinical parameters of the patients were quantified by using a neurologic disability index (NDI) as defined previously. We obtained T1-weighted magnetization-prepared rapid acquisition gradient echo images from the patients and control subjects, and we applied an optimized method of voxel-based morphometry. We performed a cross-sectional analysis to search the gray matter volume differences between the patients and control subjects. The correlation between the gray matter distribution and the duration of symptoms, immunoglobulin G index, and NDI scores was tested. We found that the cortical gray matter volume of patients was reduced in the frontotemporal regions including the bilateral cingulate cortex and amygdala. There was no correlation between the gray matter distribution of patients and the duration of symptoms or the NDI scores. The current study demonstrated gray matter volume reduction in the frontotemporal cortex of patients with SSPE without any apparent lesions on conventional MR imaging. Because the cingulate cortex and amygdala are involved in emotion processing, gray matter loss in these regions may contribute to the development of early behavioral symptoms of SSPE.

The human hippocampus at 7 T—In vivo MRI

The human hippocampus plays a central role in various neuropsychiatric disorders, such as temporal lobe epilepsy (TLE), Alzheimer's dementia, mild cognitive impairment, and schizophrenia. Its volume, morphology, inner structure, and function are of scientific and clinical interest. Magnetic resonance (MR) imaging is a widely employed tool in neuroradiological workup regarding changes in brain anatomy, (sub-) volumes, and cerebral function including the hippocampus. Gain in intrinsic MR signal provided by higher field strength scanners and concomitant improvements in spatial resolution seem highly valuable. An examination protocol permitting complete, high-resolution imaging of the human hippocampus at 7 T was implemented. Coronal proton density, T2, T2*, and fluid-attenuated inversion recovery contrasts were acquired as well as an isotropic 3D magnetization-prepared rapid acquisition gradient-echo (500 microm isotropic voxel dimension, noninterpolated). Observance of energy deposition restrictions within acceptable scan times remained challenging in the acquisition of thin, spin-echo-based sections. At the higher resolution enabled by 7 T, demarcation of the hippocampus and some internal features including gray/white matter differentiation and depiction of the hippocampal mantle becomes much more viable when compared with 1.5 T; thus, in the future, this imaging technology might help in the diagnosis of subtle hippocampal changes.

3T High-Spatial-Resolution Contrast-Enhanced MR Angiography of the Intracranial Venous System with Parallel Imaging

The diagnostic image quality of contrast-enhanced (CE) 3D MR venography (MRV) was prospectively compared with that of 2D time-of-flight (TOF) MRV and contrast-enhanced 3D magnetization-prepared rapid acquisition of gradient echo (MPRAGE) sequences for the visualization of the intracranial venous system at 3T in 22 patients. CE MRV provides high-quality images and was shown to be superior to TOF MRV and MPRAGE sequences in visualizing the normal intracranial venous system.

P1-316: Decreased white matter volumes in asymptomatic individuals at increased risk for familial Alzheimer's disease

Background: While much of structural imaging has focused on gray matter, the quantification of white matter integrity is of interest not only because of the noted white matter pathology seen in Alzheimer’s disease (AD), but also because of the apparent breakdown of myelin in AD. To date there has been no longitudinal study of white matter integrity within asymptomatic samples at elevated risk for late-onset AD, the purpose of this study. Methods: Cognitively normal participants age 50 years and above were chosen from an ongoing longitudinal study, comparing those with increased genetic risk for AD to matched controls. 95 of the high-risk and 91 of the controls had structural scans at baseline (Time 1) and 87 high-risk and 74 controls at three-year follow-up (Time 2). Participants were imaged at each time point on the same 1.5 Tesla Philips Intera-NT system equipped with Galaxy gradients (66mT/m at 110 mT/m/s). High resolution anatomical images of the brain for structural measurements were acquired using a T1weighted, 3D MP-RAGE (Magnetization Prepared Rapid Acquisition Gradient Echo) sequence with the following parameters: TR 8.6 ms, TE 3.9 ms, FOV 240 mm, 8, matrix size 256x256, slice thickness 1.5 mm, 124 slices). Pre-processing was performed using a semiautomated method, followed by the manual removal of remaining skull and dura. All measurements were conducted by one rater blind to group status. Scans were then segmented into separate tissue classes using an adaptive fuzzy C-means algorithm. Volumes of gray matter and white matter tissue as well as total brain volume were calculated. Results: At both Time 1 and Time 2, the high-risk sample showed significantly smaller white matter volumes (Time 1 p 0.05, Time 2 p 0.04). Change across the time points, however, did not significantly differ between groups (control -50ccm, high-risk -53.28ccm). Conclusions: While the similar rate of white matter loss across groups may reflect aging, this would not provide an explanation for the initial significantly smaller white matter volume seen in the high-risk group. Further study is needed to more fully understand the significance of reduced white matter volume as it relates to AD. P1-317 DIFFUSION TENSOR IMAGING IN FRONTOTEMPORAL LOBAR DEGENERATION

IC-P2-076: White matter volume in individuals at increased risk for Alzheimer's disease

While much of structural imaging has focused on gray matter, the quantification of white matter integrity is of interest not only because of the noted white matter pathology seen in Alzheimer's disease (AD), but also because of the apparent breakdown of myelin in AD. To date there has been no longitudinal study of white matter integrity within asymptomatic samples at elevated risk for late-onset AD, the purpose of this study. Cognitively normal participants age 50 years and above were chosen from an ongoing longitudinal study, comparing those with increased genetic risk for AD to matched controls. 95 of the high-risk and 91 of the controls had structural scans at baseline (Time 1) and 87 high-risk and 74 controls at three-year follow-up (Time 2). Participants were imaged at each time point on the same 1.5 Tesla Philips Intera-NT system equipped with Galaxy gradients (66mT/m at 110 mT/m/s). High resolution anatomical images of the brain for structural measurements were acquired using a T1-weighted, 3D MP-RAGE (Magnetization Prepared Rapid Acquisition Gradient Echo) sequence with the following parameters: TR=8.6 ms, TE=3.9 ms, FOV=240 mm, θ=8°, matrix size =256x256, slice thickness=1.5 mm, 124 slices). Pre-processing was performed using a semi-automated method, followed by the manual removal of remaining skull and dura. All measurements were conducted by one rater blind to group status. Scans were then segmented into separate tissue classes using an adaptive fuzzy C-means algorithm. Volumes of gray matter and white matter tissue as well as total brain volume were calculated. At both Time 1 and Time 2, the high-risk sample showed significantly smaller white matter volumes (Time 1 p = 0.05, Time 2 p = 0.04). Change across the time points, however, did not significantly differ between groups (control = -50ccm, high-risk = -53.28ccm). While the similar rate of white matter loss across groups may reflect aging, this would not provide an explanation for the initial significantly smaller white matter volume seen in the high-risk group. Further study will be needed to more fully understand the significance of reduced white matter volume as it relates to AD.

Bilateral pulvinar signal intensity decrease on t2-weighted images in patients with aspartylglucosaminuria

Aspartylglucosaminuria (AGU) is an autosomal recessive lysosomal disease caused by deficiency of aspartylglucosaminidase. A thalamic T2 signal intensity decrease is associated with lysosomal diseases. To investigate thalamic signal intensity in AGU by performing a retrospective review of brain magnetic resonance (MR) imaging studies of AGU patients. A total of 25 MR examinations were available for 11 patients aged between 3 and 32 years (four patients underwent bone marrow transplantation). Of these, 13 examinations were performed after bone marrow transplantation. Five patients had from two to six examinations, and six patients had one examination each. In every patient, the diagnosis of AGU was confirmed by blood and urine tests. Eighteen examinations were performed with a 1.0T imager including dual spin-echo T2 and proton density (PD) axial and coronal images, and 10 examinations also included T1-weighted images. Seven examinations were performed with a 1.5T imager including turbo spin-echo axial and coronal T2-weighted images and axial fluid-attenuated inversion recovery (FLAIR) images; three examinations included T1-weighted three-dimensional magnetization-prepared rapid acquisition gradient-echo (3D MPRAGE) images. The signal intensity of the thalamus and pulvinar in every sequence was compared to that of the putamina. In AGU, thalamic alterations were first detectable on T2-weighted images (25 examinations in 11 patients) from the age of 3 years 6 months, showing decreased signal intensity in 21 of 24 examinations. T1-weighted images (13 examinations) showed slightly increased thalamic signal intensity in five out of seven examinations from the age of 7 years, and PD images (19 examinations) showed decreased signal intensity from the age of 16 years (three examinations). The pulvinar showed decreased signal intensity on spin-echo T2-weighted images for 14 of 18 examinations or on FLAIR sequences for seven of seven examinations from the age of 6 years and 6 months, both in patients with and without bone marrow transplantation, but no pulvinar alterations were observable on T1 and PD images. In AGU, the thalamus is affected. Pulvinar changes are visible only on T2-weighted images, and these may be the first changes reported in the group of lysosomal diseases.

Multi-contrast, isotropic, single-slab 3D MR imaging in multiple sclerosis

To describe signal and contrast properties of an isotropic, single-slab 3D dataset [double inversion-recovery (DIR), fluid-attenuated inversion recovery (FLAIR), T2, and T1-weighted magnetization prepared rapid acquisition gradient-echo (MPRAGE)] and to evaluate its performance in detecting multiple sclerosis (MS) brain lesions compared to 2D T2-weighted spin-echo (T2SE). All single-slab 3D sequences and 2D-T2SE were acquired in 16 MS patients and 9 age-matched healthy controls. Lesions were scored independently by two raters and characterized anatomically. Two-tailed Bonferroni-corrected Student's t-tests were used to detect differences in lesion detection between the various sequences per anatomical area after log-transformation. In general, signal and contrast properties of the 3D sequences enabled improved detection of MS brain lesions compared to 2D-T2SE. Specifically, 3D-DIR showed the highest detection of intracortical and mixed WM-GM lesions, whereas 3D-FLAIR showed the highest total number of WM lesions. Both 3D-DIR and 3D-FLAIR showed the highest number of infratentorial lesions. 3D-T2 and 3D-MPRAGE did not improve lesion detection compared to 2D-T2SE. Multi-contrast, isotropic, single-slab 3D MRI allowed an improved detection of both GM and WM lesions compared to 2D-T2SE. A selection of single-slab 3D contrasts, for example, 3D-FLAIR and 3D-DIR, could replace 2D sequences in the radiological practice.

Brain Response Correlates of Decisional Capacity in Schizophrenia: A Preliminary fMRI Study

Brain Response Correlates of Decisional Capacity in Schizophrenia: A Preliminary fMRI Study

Voxel-based morphometry study of brain volumetry and diffusivity in amyotrophic lateral sclerosis patients with mild disability.

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by the progressive and simultaneous degeneration of upper and lower motor neurons. The pathological process associated to ALS, albeit more pronounced in the motor/premotor cortices and along the corticospinal tracts (CST), does not spare extra-motor brain gray (GM) and white (WM) matter structures. However, it remains unclear whether such extra-motor cerebral abnormalities occur with mildly disabling disease, and how irreversible tissue loss and intrinsic tissue damage are interrelated. To this end, we used an optimized version of voxel-based morphometry (VBM) analysis to investigate the patterns of regional GM density changes and to quantify GM and WM diffusivity alterations of the entire brain from mildly disabled patients with ALS. A high-resolution T1-weighted 3D magnetization-prepared rapid acquisition gradient echo and a pulsed gradient spin-echo single shot echo-planar sequence of the brain were acquired from 25 mildly disabled patients with ALS and 18 matched healthy controls. An analysis of covariance was used to compare volumetry and diffusivity measurements between patients and controls. Compared with controls, ALS patients had significant clusters of locally reduced GM density (P < 0.001) in the right premotor cortex, left inferior frontal gyrus (IFG), and superior temporal gyrus (STG), bilaterally. In ALS patients contrasted to controls, we also found significant clusters of locally increased MD (P < 0.001) in the splenium of the corpus callosum and in the WM adjacent to the IFG, STG, and middle temporal gyrus (MTG) of the right hemisphere, and in the WM adjacent to the MTG and lingual gyrus in the left hemisphere. Compared with controls, ALS patients also had significant clusters of locally decreased FA values (P < 0.001) in the CST in the midbrain and corpus callosum, bilaterally. This study supports the notion that ALS is a multisystem disorder and suggests that extra-motor involvement may be an early feature of the disease.