Journal of neuroimaging : official journal of the American Society of Neuroimaging
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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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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.
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Cortical processing involved in seemingly similar tasks may differ in important ways. The authors mapped cortical regions engaged in a commonly performed picture naming task, seeking differences by semantic category. Functional magnetic resonance imaging was used during presentation of standardized line drawings in 18 healthy right-handed female participants, comparing living versus nonliving entities. ⋯ Activation of right inferior temporal cortex (BA19 and BA37) was greater during naming of living versus nonliving category items. No category differences in activation strength in the left temporal lobe were observed. The authors conclude that visual semantic operations may involve visual association cortex in the right temporal lobe in women.
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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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Although anterior circulation transient ischemic attacks (TIAs) tend to be more common in patients with extra- cranial carotid arterial disease than in those with intracranial carotid or middle cerebral arterial disease, the authors recently encountered 4 patients with both recurrent, stereotypical TIAs as well as isolated stenosis of their petrous internal carotid artery (ICA). While the gold standard for establishing the diagnosis of intracranial large-artery disease has always been conventional angiography, magnetic resonance angiography changes, confirmed with intra-arterial digital subtraction angiography in 2 of these patients, were quite sufficient to define the occlusive disease in each of the cases. Petrous ICA stenosis is not uncommon, but it has often been overshadowed by the search for extracranial ICA disease that might be amenable to surgical reconstruction.