Non-neonatal hypoxic-ischemic encephalopathy is a clinical condition often related to cardiopulmonary arrest that demands critical management and treatment decisions. Management depends mainly on the degree of neurological impairment and prognostic considerations. Computed tomography (CT) is often used to exclude associated or mimicking pathology. If any, only nonspecific signs such as cerebral edema, sulci effacement, and decreased gray matter (GM)/white matter (WM) differentiation are evident. Pseudosubarachnoid hemorrhage, a GM/WM attenuation ratio <1.18, and inverted GM attenuation are associated with a poor prognosis. Magnetic resonance (MR) imaging is more sensitive than CT in assessing brain damage in hypoxic-ischemic encephalopathy. Some MR findings have similarities to those seen pathologically, based on spatial distribution and time scale, such as lesions distributed in watershed regions and selective injury to GM structures. In the acute phase, lesions are better depicted using diffusion-weighted imaging (DWI) because of the presence of cytotoxic edema, which, on T2-weighted images, only become apparent later in the early subacute phase. In the late subacute phase, postanoxic leukoencephalopathy and contrast enhancement could be observed. In the chronic phase, atrophic changes predominate over tissue signal changes. MR can be useful for estimating prognosis when other tests are inconclusive. Some findings, such as the extent of lesions on DWI and presence of a lactate peak and depleted N-acetyl aspartate peak on MR spectroscopy, seem to have prognostic value.

Purpose:To estimate between-scanner functional MRI (fMRI) reproducibility in a multisite study. Materials and Methods:A total of five identical 1.5T MR systems were used to repeatedly scan five subjects while performing a finger tapping task. A two-way (scanners, subjects) random effects analysis of variance (ANOVA) was used to estimate between-scanner and between-subject variability on two outcome variables: task-related mean blood oxygenation level dependent (BOLD) signal change and volume of activation within a motor region-of-interest (ROI). Results:Between-scanner variability of fMRI data accounted for a small proportion of the total variation in the BOLD signal change (8.34%, P ϭ 0.114) and volume of activation (5.46%, P ϭ 0.203). Between-subject variation accounted for more than half of the total variation for both measurements (57.17% and 54.46%, respectively, P Ͻ 0.01). Conclusion:These results support the feasibility of multisite studies using identical scanner systems. MULTISITE STUDIES may remediate some of the limitations in current functional magnetic resonance imaging (fMRI) research, in particular the difficulties in assembling large sample sizes in clinical populations. Sufficient reproducibility of fMRI measurements across scanners is necessary for multisite investigations. In an extreme situation, if most of the variance in the measurements were attributable to differences between scanners rather than the factors of interest (i.e., subjects, tasks), fMRI results would be largely site-dependent and the validity of pooling results over sites would be in doubt. Estimating variance components is thus important to assess the validity of multisite measurements.Previous quantitative estimates of the effect of between-scanner variability on functional measurements are, to our knowledge, limited to the results of an experiment performed by the Biomedical Informatics Research Network (1,2). This study identified two scanner-related variables (field strength and type of k-space) in addition to the particular subject under study as significant predictors of result accuracy. However, no estimate of the variance attributable to each of these factors was reported. Other multiscanner investigations have assessed reproducibility using qualitative comparison of the activation maps (3,4).In the present work, we report the results of a pilot investigation of between-scanner reproducibility. Five subjects were scanned in five magnetic resonance systems on the same day, while performing a blocked design finger-tapping paradigm. Our analysis focuses on a region of interest (ROI) in the motor strip. Reproducibility was estimated using random effects variance components such that the total variance was partitioned into between-scanner, between-subject, and residual components (5). MATERIALS AND METHODS Participants and TaskParticipants were five healthy, right-handed volunteers (four female), aged 25 to 30 years. The experimental condition was self-paced finger tapping with the right index finger, and the control cond...

New ischemic lesions seen on DW-MRI were present in both groups in >60%, but the number of lesions per patient was greater in the ANGIOGUARD group. No death or disabling stroke occurred during at least 1 year of follow-up in both cohorts.

Wernicke's encephalopathy (WE) is a serious neurological disorder secondary to thiamine deficiency. Improved recognition by radiologists and allied health providers of the different clinical settings and imaging findings associated with this emergency can optimise the management of this condition and help prevent its severe consequences. The aim of this study is to illustrate the broad clinicoradiological spectrum of non-alcoholic WE, while emphasising atypical MRI findings.