Journal of neuroimaging : official journal of the American Society of Neuroimaging
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Broca's area, which includes the pars triangularis (PTR), is a neuroanatomical region important in speech and language production. Linear measures of the PTR have been found to be asymmetric, with the direction of the asymmetry correlating with language dominance determined by Wada testing. It is unclear, however, whether these linear measurements correlate with volumetric measures, and it is also unknown whether white matter and/or gray matter contribute differentially to these asymmetries. ⋯ Linear measures of the left and right hemispheres were highly correlated with volumetric measures. Underlying gray and white matter both contributed to PTR asymmetry. Anatomical boundaries and four configurations (V, U, Y, and J) are discussed with reference to potential interhemispheric differences.
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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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The purpose of this study was to evaluate the visibility of the IXth to XIIth cranial nerves using different magnetic resonance sequences. Thirty healthy volunteers underwent magnetic resonance imaging at 1.5 T using 3-dimensional constructive interference in steady state (CISS) sequence (TR = 17 ms, TE = 8.08 ms, alpha = 70 degrees), 3-dimensional magnetization-prepared rapid gradient echo (MP-RAGE) sequence (TR = 11.08 ms, TE = 4.3 ms, alpha = 15 degrees), and T2-weighted (w) 2-dimensional turbo spin echo (TSE) sequence (TR = 4000 ms, TE = 102 ms, alpha = 180 degrees, slice thickness = 2 mm). Visibility of the IXth to XIIth cranial nerves in each sequence was evaluated by consensus of 2 radiologists using an evaluation scale from 1 (excellently visible) to 5 (not visible). ⋯ However, even in 3-dimensional high-resolution sequences, segments of nerves are not always visualized. A combination of 3-dimensional CISS and 3-dimensional MP-RAGE proved to be useful to visualize the IXth to XIIth cranial nerves, whereas the 2-dimensional technique failed. Further investigations using 3-dimensional MP-RAGE with contrast medium should be performed in the case of abnormality.
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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.