Journal of neuroimaging : official journal of the American Society of Neuroimaging
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Brain atrophy may occur early in the course of multiple sclerosis (MS) and may be associated with disability. Brain magnetic resonance imaging (MRI) of 114 MS patients (group A) were analyzed for regional atrophy (vs age-/gender-matched controls) and T1 and T2 lesions using 4-point rating systems. Thirty-five separate patients (group B) were analyzed for cortical atrophy (ordinal scale), third ventricular width, and total T2 hyperintense lesion volume (computer assisted). ⋯ Mean kappa coefficients of ordinal ratings were 0.9 (intraobserver) and 0.8 (interobserver). Ordinal ratings correlated well with quantitative assessments. The authors conclude that brain atrophy is closely associated with physical disability and clinical course in MS patients and can be appreciated using a semiquantitative MRI regional rating system.
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Diffusion-weighted magnetic resonance imaging (DWI) detects acute ischemic infarcts with high lesion conspicuity. Determination of infarct age is difficult on DWI alone because infarct signal intensity (SIinfarct) on DWI is influenced by T2 properties ("T2 shine-through"). Maps of the apparent diffusion coefficient (ADC) reflect pure diffusion characteristics without T2 effects but have low lesion conspicuity. ⋯ All infarcts > 10 days old had an eDWI signal intensity lower than control tissue (hypointense appearance). The authors concluded that the use of eDWI, as a single set of images, reliably differentiates acute infarcts (< or = 5 days old) from infarcts > 10 days old. This feature would be expected to be helpful when the distinction between acute and nonacute infarction cannot be determined on clinical grounds.
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The aim of this study was to assess the prognostic value of early brain scintigraphy in head injury in relation to long-term neuropsychological behavior. Twenty-four patients underwent technetium-99m (Tc-99m) ethyl cysteinate dimer single photon emission computed tomography (SPECT) within 1 month of the trauma. Scintigraphic abnormalities were evaluated both visually and semiquantitatively using the brain-to-cerebellum ratio method. ⋯ The brain-to-cerebellum ratios in the left basal ganglia and brain stem were significantly decreased in patients with memory disorders (P = .03 and P = .02, respectively). Moreover, SPECT visual analysis indicated that low uptake in the basal ganglia, thalamus, and brain stem was associated with subsequent motor deficit, frontal behavior, and language and memory disorders. The authors conclude that brain SPECT can be valuable in predicting the neuropsychological behavior of survivors of severe head injury.
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The authors investigate the reproducibility of metabolite signals measured with proton magnetic resonance spectroscopy (1H-MRS) acquired from the human hippocampus in controls and in a phantom. Two 1H-MRS studies separated by 3 weeks were performed in 8 healthy volunteers and in a phantom. N-acetyl compounds (NA), choline (Ch), and creatine (Cr) peak areas and ratios were measured and compared using percentage variation, and Pearson Correlation Coefficient at the level of every voxel, the level of 1 hippocampus (5 voxels), and the level of 2 hippocampi (10 voxels). ⋯ Left-right asymmetry indices showed similar and limited inter-hemispheric asymmetry in repeated examination. This study suggests that 1H-MRS reproducibility performance is adequate for the study and monitoring of human hippocampus function when NA ratios and the sum of multiple voxels are considered. Individual metabolite peaks and single-voxel measurements have low reproducibility at 1.5 T and should be used only with clearly established statistical parameters.
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Case Reports
In vivo 1H magnetic resonance spectroscopic measurement of brain glycine levels in nonketotic hyperglycinemia.
Nonketotic hyperglycinemia (NKH) is an autosomal recessive disorder of glycine metabolism. Defective glycine cleavage causes elevated concentrations of glycine in plasma, urine, and cerebrospinal fluid. A longitudinal study using magnetic resonance imaging (MRI) and single-voxel 1H magnetic resonance spectroscopy (MRS) was performed on an infant with the typical clinical picture of NKH. ⋯ At the age of 10 months, MRI showed normal brain structure, while MRS detected a prominent glycine peak in the brain. Repeat MRS at the age of 13 months showed a small increase in glycine peak and a prominent glutamate/glutamine peak not previously detected. The MRS measurements were consistent with the slight increase in blood glycine level and the elevation in glutamine level, indicating that 1HMRS can be a valuable tool in the diagnosis and monitoring of treatment effects in patients with NKH.