Pachygyria in Weaver syndrome.
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Abnormalities, Multiple↗
Biomedical subjects
S N Breiter
Publications and source records attributed to S N Breiter.
Defining and categorizing leukoencephalopathies of unknown origin: MR imaging approach.
PURPOSE: To categorize leukoencephalopathies of unknown origin into a few major groups by using magnetic resonance (MR) imaging criteria to facilitate further studies, and to assess the possibility of defining "new" (i.e., until now unknown) disease entities within these major groups. MATERIALS AND METHODS: MR images of 92 patients (55 male, 37 female; mean age, 9.3 years) with a leukoencephalopathy were examined by using a scoring list of 68 items. Seven major categories were defined according to the predominant location of the white matter abnormalities. Statistical analysis was used to assess the validity of these seven categories. RESULTS: Statistical analysis results showed that the seven categories could be well distinguished by either using the defining variables initially accepted as inclusion criteria or selecting a few other variables found to have discriminating value. The additional variables confirmed that the categories are essentially distinct and vary systematically with regard to items other than the inclusion criteria. The existence of two recently defined leukoencephalopathies was confirmed, but no consistent evidence of other new disease entities could be provided. CONCLUSION: Establishing these seven categories helps in the interpretation of individual studies by demonstrating features that the patient has in common with other patients, and it may facilitate further research on homogeneous subgroups of patients and allow pooling of data across multiple centers.
Brain↗
Subarachnoid contrast enhancement after spinal angiography mimicking diffuse subarachnoid hemorrhage.
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Aged↗
MRI brain changes in subjects with Down syndrome with and without dementia.
Individuals with Down syndrome (DS), a disorder of known genetic etiology (trisomy of chromosome 21), exhibit several types of structural brain abnormalities that are detectable pathologically and by MRI. In addition, in middle age, individuals with DS develop histological and, in some cases, clinical features of Alzheimer's disease (AD). Abnormalities in MRI scans of 50 adults with DS, 11 of whom had clinical dementia, are described and compared with those of 23 cognitively normal, healthy subjects who were matched for age, sex, and race. Qualitative visual analogue scale (VAS) ratings on MRI hard copies for all subjects and computer-aided volume measures for a subsample of subjects were carried out. On VAS, subjects with DS had larger lateral ventricles, a higher frequency of posterior fossa arachnoid cysts/megacisterna magna and fewer scans rated as normal compared with controls. Quantitatively, total brain and gray-matter volumes were reduced in DS, as were the volumes of the left hippocampus and amygdala; ventricle volumes were larger. Post hoc comparisons of subjects with DS with and without dementia revealed that on VAS the former had more generalized atrophy for age, mesial temporal shrinkage, and third ventricular enlargement. Similarly, total brain, left hippocampus, and left amygdala volumes were reduced quantitatively in subjects with DS with dementia, while ventricular volumes were increased.
Adult↗
Reliability and validity of MRI measurement of the amygdala and hippocampus in children with fragile X syndrome.
Evidence from numerous structural magnetic resonance imaging (MRI) studies has converged to implicate mesial temporal lobe structures in the pathophysiology of several developmental and psychiatric disorders. Efforts to integrate the results of these studies are challenged, however, by the lack of consistency, detail and precision in published protocols for the manual measurement of the amygdala and hippocampus. In this study, we describe a highly detailed, standardized protocol for measuring the amygdala and the hippocampus. Within the context of this protocol, we tested the inter- and intra-rater reliability of two frequently cited methods for normalizing the anatomical position of the amygdala and hippocampus prior to measurement. One method consisted of creating a coronal data set in which images are rotated in a plane perpendicular to the long axis of the hippocampus. The second method consisted of creating a coronal data set in which images are rotated in a plane perpendicular to the axis connecting the anterior and posterior commissures. Inter- and intra-rater reliability coefficients (using the intraclass correlation) ranged from 0.80 to 0.98, indicating that both methods for positional normalization are highly reliable. In addition, we tested the validity of each method by comparing the temporal lobe anatomy of children with fragile X syndrome to a group of unaffected children matched by age and gender. We found that hippocampal volumes in children with fragile X were significantly increased when either rotational method was used. These results replicated previous findings, suggesting that either method can be validly applied to neuronanatomic studies of pediatric populations.
Adolescent↗
Brain magnetic resonance imaging in suspected extrapyramidal cerebral palsy: observations in distinguishing genetic-metabolic from acquired causes.
Experienced clinicians recognize that some children who appear to have static cerebral palsy (CP) actually have underlying genetic-metabolic disorders. We report a series of patients with motor disorders seen in children with extrapyramidal CP in whom brain magnetic resonance imaging abnormalities provided important diagnostic clues in distinguishing genetic-metabolic disorders from other causes. One cause of static extrapyramidal CP, hypoxic-ischemic encephalopathy at the end of a term gestation, produces a characteristic pattern of hyperintense signal and atrophy in the putamen and thalamus. Other signal abnormalities and atrophy in the putamen, globus pallidus, or caudate can point to genetic-metabolic diseases, including disorders of mitochondrial and organic acid metabolism. Progress in understanding and treating genetic diseases of the developing brain makes it essential to diagnose disorders that masquerade as static CP. Brain magnetic resonance imaging is a useful diagnostic tool in the initial evaluation of children who appear to have CP.
Acidosis, Lactic↗
Improved tissue characterization in adrenoleukodystrophy using magnetization transfer imaging.
OBJECTIVE: We performed this study to evaluate the usefulness of magnetization transfer (MT) imaging techniques and magnetization transfer ratio (MTR) measurements in assessing patients with adrenoleukodystrophy (ALD). SUBJECTS AND METHODS: Twelve patients who encompassed the range of ALD phenotypes were evaluated prospectively with MR and MT imaging (including digital subtraction images). The MT images and spin-echo MR images were compared by two staff neuroradiologists and a staff neurologist for extent of disease, different zones of involvement, and the presence of enhancement. MTR measurements were obtained from affected and unaffected regions of the brain. RESULTS: Eight of the 12 patients exhibited gadolinium enhancement. In seven of these patients, the MT subtraction images showed two zones of abnormal signal within the affected white matter. Their MTR measurements were classified as zone 1 (mean MTR, 35%; SD, 6%) and zone 2 (mean MTR, 20%; SD, 6%). Three of the other patients showed a single zone of involvement corresponding to the affected white matter on the standard spin-echo MR images. Their MTR measurements were similar to that of zone 1. The remaining two patients had no demonstrable signal abnormalities on any of the images. We noted no difference in any of the 12 subjects in the extent of white matter involvement on any of the imaging techniques. The MTR measurements in the unaffected white matter (mean MTR, 46%; SD, 5%) approximated established MTRs in white matter of normal volunteers. CONCLUSION: MT imaging and MTR measurements are helpful clinical techniques that may improve the evaluation of patients with ALD, particularly in the proposed ability of these techniques to divide the affected white matter into different zones that correspond to specific pathologic areas. These techniques can help the understanding of pathogenetic mechanisms and the evaluation of therapies.
Adolescent↗
Quantitative proton spectroscopy of canine brain: in vivo and in vitro correlations.
Quantitative, single-voxel proton NMR spectroscopy of normal brain was performed in five adult beagle dogs using the cerebral water signal as an internal intensity reference. The same brain regions were then rapidly isolated and frozen using a pneumatic biopsy drill, perchloric acid extracted, and analyzed by biochemical assay and high-resolution NMR spectroscopy. The concentrations of the major resonances in the in vivo and in vitro spectra were compared, and good agreement was found between the different measurements. The in vivo spectra contained three peaks at 3.21, 3.04, and 2.02 ppm, which are usually assigned to trimethylamines (TMA), creatines, and N-acetyl derivatives (NAc), which corresponded to be the following metabolite concentration values: 1.7 +/- 0.6, 7.7 +/- 2.1, and 10.9 +/- 2.7 mumol/g wet weight respectively. In vitro, the following metabolite concentrations were measured: glycerophosphocholine (GPC) 1.3 +/- 0.2, phosphocholine (PC) 0.5 +/- 0.1, phosphocreatine (PCr) 2.6 +/- 0.4, creatine (Cr) 5.9 +/- 1.4, and N-Acetyl aspartate (NAA) 8.9 +/- 1.8 mumol/g wet weight. Therefore, the 3.21 ppm resonance observed in the in vivo spectrum is predominantly GPC and PC in a ratio of 2.6:1, the 3.04 ppm resonance is Cr and PCr in a ratio of 2.3:1, and the 2.02 ppm resonance is predominantly (approximately 80%) NAA with small contributions from N-acetylaspartylglutamate (NAAG) and glutamate. The data presented here validate the technique of water referencing as a simple and convenient means of quantitating single-voxel in vivo proton NMR spectra of the brain.
Animals↗
Proton MR spectroscopy in patients with seizure disorders.
PURPOSE: To evaluate the ability of proton MR spectroscopy to detect metabolic abnormalities in the seizure focus of humans with epilepsy. METHODS: Single-voxel MR spectroscopy and MR imaging was performed in a group of 13 patients with a variety of seizure disorders and in the temporal lobes of 14 healthy volunteers. Signals from choline, creatine, N-acetyl-L-aspartate, and lactate were quantitated in both the epileptogenic focus and the contralateral brain region. RESULTS: In normal temporal lobe, concentrations of choline, creatine, and N-acetyl-L-aspartate were 2.0 +/- 0.7, 7.8 +/- 1.9, and 11.0 +/- 2.1 mumol/g wet weight, respectively, with no detectable lactate. In all patients, a reduction in the N-acetyl-L-aspartate signal was observed in the electrically defined (scalp electroencephalogram) seizure focus compared with the mirror-image contralateral side. Lactate was elevated only in patients who had seizures during or immediately before the MR examination. Seven of 13 patients studied had normal MR examinations. CONCLUSIONS: Proton spectroscopy demonstrates alterations in N-acetyl-L-aspartate and lactate levels that can be used to locate the epileptogenic focus and may be a useful adjunctive diagnostic technique for the evaluation of patients with seizures who are eligible for resective surgery.
Adolescent↗