Diffuse Metabolic Abnormalities in Reversible Posterior Leukoencephalopathy Syndrome
Florian S. Eichlera,
Paul Wangb,
Robert J. Witykc,
Norman J. Beauchamp, Jrb and
Peter B. Barkerb
a Department of Neurogenetics, The Johns Hopkins University, Baltimore, MD
b Kennedy Krieger Institute, and the Departments of Radiology The Johns Hopkins University, Baltimore, MD
c Department of Neurology, The Johns Hopkins University, Baltimore, MD
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FIG 1. Patient 1. Fluid-attenuated inversion recovery (FLAIR) MR images, apparent diffusion coefficiency (ADC) maps, diffusion-weighted images (DWI), metabolic choline (Cho), creatine (Cr), N-acetylaspartate (NAA) and lipid images, and spectra are shown.
A, Images from the second of four MR spectroscopic imaging sections. Spectra are shown from selected regions of interest in frontal white matter, mesial occipital gray matter, and occipital white matter with fluid-attenuated inversion recovery MR imaging hyperintensity.
B, Images from the third of four MR spectroscopic imaging sections. Spectra are shown from frontal white matter, with both normal (right) and abnormal (left) MR imaging appearance, body of the corpus callosum, and parietal white matter with fluid-attenuated inversion recovery MR imaging hyperintensity. High levels of creatine and choline and mildly reduced N-acetylaspartate are apparent in both gray and white matter regions with normal MR imaging appearance. Lipid signals most likely result from head motion. Metabolic images show hypointensity in regions of abnormal MR imaging appearance, suggesting dilution of all metabolite concentrations (increased water content). Apparent diffusion coefficiency values in these regions are also elevated compared with normal values.
C, Fluid-attenuated inversion recovery MR images, obtained at 2-month follow-up, show normalization of signal intensity with only a small region of fluid-attenuated inversion recovery MR imaging hyperintensity adjacent to the posterior horns of the lateral ventricles.
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FIG 2. Patient 2. T2-weighted MR images, metabolic choline (Cho), creatine (Cr), N-acetylaspartate (NAA), and lipid images, and spectra from selected regions of interest (frontal and posterior white matter, mesial occipital gray matter) are shown.
A, Images obtained at time of episode. Quantitative analysis (Table) indicated that the primary abnormality was increased levels of choline and creatine with mildly lower N-acetylaspartate.
B, Images obtained at 2-month follow-up. A globally reduced ratio of N-acetylaspartate:choline is apparent throughout the brain, which has normalized by the time of follow-up. As in (Figure 1), posterior edematous regions exhibit lower signal intensity on MR spectroscopic images compared with other regions. MR spectroscopic imaging hypointensity in the frontal lobe most noticeable in the creatine image is an artifact due to magnetic field inhomogeneity in this region.
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