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PubMed2001

The effect of repeated sublethal ischemia on NO/cGMP signal transduction system in gray matter of the rabbit spinal cord.

BACKGROUND: The activation of the soluble guanylate cyclase and the production of cyclic 3',5'-guanosine monophosphate (cGMP) have been reported as the primary cellular response to nitric oxide (NO) in the nervous system. Previous results indicated, that three-fold sublethal ischemia repeated at 1-h intervals induces damage in gray matter of the spinal cord. However, little is known about the changes of NO/cGMP signal transduction system in gray matter of the spinal cord under conditions of repeated sublethal ischemia. MAIN PURPOSE: The aim of this study was to compare the catalytic NOS activity and cGMP concentration in the gray matter regions of lumbosacral spinal cord segments (dorsal horn, zona intermedia, ventral horn) after three (8-, 8-, 9-min) sublethal occlusions repeated at 1-h intervals. METHODS: Twenty male rabbits, weighing 2.5-3.5 kg were used in the experiments. They were divided into two experimental groups: (1) control animals (n = 10); (2) animals subjected to three brief (8-, 8-, 9-min) occlusions, each time repeated by reperfusion lasting for 1 h (n = 10). Ischemia of lumbosacral segments was induced by ligation of the abdominal aorta just below the left renal artery (DeGirolami and Zivin, 1982). The catalytic NOS activity was determined by conversion of [3H]-L-arginine to [3H]-L-citrulline according to the method of Bredt and Snyder (1990) slightly modified by Strosznajder and Chalimoniuk (1996). cGMP concentration was assessed by radioimmunoassay method (RIA). RESULTS: Repeated sublethal ischemia evoked a slight increase in catalytic NOS activity over control values in all gray matter regions. On the other hand, cGMP concentration in gray matter regions has a decreasing character, in a descending order: dorsal horn > zona intermedia > ventral horn. A significant impairment of NO-cGMP signal transduction was detected in the intermediate zone and ventral horns. CONCLUSIONS: Our results indicate that threefold (8-, 8-, 9-min) sublethal ischemia repeated in 1 h intervals of reperfusion causes the impairment of NO/cGMP signal transduction system in gray matter of lumbosacral spinal cord segments and the extent of impairment is region-specific. This finding correlates with the neurological hindlimbs impairment in experimental animals. (Tab. 1, Fig. 2, Ref. 39.)

Animals↗
PubMedDate not supplied

Etiology of cortical and white matter lesions in cyclosporin-A and FK-506 neurotoxicity.

BACKGROUND AND PURPOSE: The etiology of the neurotoxicity associated with cyclosporin-A (CsA) and FK-506 treatment is not fully understood. At our institution, we noticed a distinct, abrupt change in the imaging characteristics of CsA and FK-506 neurotoxicity, which consisted of a shift in lesion morphology from a white matter abnormality to a mixed cortical and white matter pattern. The purpose of this study was to assess clinical parameters that might explain this change. METHODS: Twenty-two patients had a neurotoxic reaction and brain imaging changes while receiving CsA or FK-506. Nineteen patients received allogeneic bone marrow transplants, and three had aplastic marrow disorders. Fifty-one imaging studies (CT or MR imaging) were obtained, and lesion characteristics, locations, and time courses were evaluated along with relevant clinical data. RESULTS: Nine patients who had been conditioned for transplantation with cyclophosphamide and chemotherapy (busulfan or thiotepa) had a mixed pattern of cortical and white matter involvement (57 lesions). Isolated white matter involvement (62 lesions) developed in three nontransplant patients and 10 transplant patients conditioned with cyclophosphamide and total-body irradiation. All lesions occurred at typical brain watershed zones. Lesion enhancement was noted in two patients conditioned with chemotherapy. Initial images demonstrated characteristic lesions in 15 patients (68%). Initial images were normal in four patients (18%) and nonspecific in three patients (14%). CONCLUSION: Lesion location in CsA and FK-506 neurotoxicity may depend on the presence or type of conditioning used before bone marrow transplantation. Nontransplant patients or those conditioned with total-body irradiation develop white matter lesions, whereas those conditioned with chemotherapy develop mixed cortical and white matter lesions.

Adult↗
PubMed2002

Cortical gray matter loss in treatment-naïve alcohol dependent individuals.

BACKGROUND: Most studies of the impact of alcohol dependence on the brain have examined individuals in treatment. Such samples represent a small proportion of alcoholics in the general population. Such samples may embody a bias (Berkson's fallacy) if the association between variables (for example, alcoholism and cortical gray matter loss) differs between the population of alcoholics in treatment and alcoholics in the general population. Our objective was to determine if treatment-naïve alcoholics show structural brain changes versus controls and to compare our findings with reports evaluating alcoholic samples drawn from treatment populations. METHODS: Structural MRI was used to assess whole brain and regional volumes of cortical gray matter and white matter in 24 young to middle-aged treatment-naïve alcohol-dependent males versus 17 controls. RESULTS: Cortical gray matter volumes in alcohol-dependent individuals were negatively associated with age and lifetime duration of alcohol use (which were highly confounded). These subjects showed reduced whole brain (p < 0.05), prefrontal (p < 0.01), and parietal (p < 0.05) cortical gray matter compared with controls. White matter and temporal cortex, tissues that usually show volume reductions in samples drawn from treatment, did not differ between treatment-naïve alcoholics and controls (all p > 0.40). CONCLUSIONS: Our findings are consistent with the hypothesis that structural brain changes in treatment-naïve alcoholics are less severe than those reported in clinical samples of alcoholics, perhaps due to less concomitant psychopathology and a reduced severity of alcoholism in treatment-naïve alcoholics. However, caution must be taken when comparing our findings with results from clinical samples, as we did not directly compare treatment-naïve alcoholics with treated alcoholics and our treatment-naïve sample tended to be younger than the (clinical) samples reported in the literature. Nevertheless, we suggest that most of the reports of the central nervous system consequences of alcoholism may not accurately describe the majority of alcoholic-dependent individuals.

Adult↗
PubMed2002

Diffusion-tensor MR imaging of gray and white matter development during normal human brain maturation.

BACKGROUND AND PURPOSE: Conventional MR imaging findings of human brain development are thought to result from decreasing water content, increasing macromolecular concentration, and myelination. We use diffusion-tensor MR imaging to test theoretical models that incorporate hypotheses regarding how these maturational processes influence water diffusion in developing gray and white matter. METHODS: Experimental data were derived from diffusion-tensor imaging of 167 participants, ages 31 gestational weeks to 11 postnatal years. An isotropic diffusion model was applied to the gray matter of the basal ganglia and thalamus. A model that assumes changes in the magnitude of diffusion while maintaining cylindrically symmetric anisotropy was applied to the white matter of the corpus callosum and internal capsule. Deviations of the diffusion tensor from the ideal model predictions, due to measurement noise, were estimated by using Monte Carlo simulations. RESULTS: Developing gray matter of the basal ganglia and developing white matter of the internal capsule and corpus callosum largely conformed to theory, with only small departures from model predictions in older children. However, data from the thalamus substantially diverged from predicted values, with progressively larger deviations from the model with increasing participant age. CONCLUSION: Changes in water diffusion during maturation of central gray and white matter structures can largely be explained by theoretical models incorporating simple assumptions regarding the influence of brain water content and myelination, although deviations from theory increase as the brain matures. Diffusion-tensor MR imaging is a powerful method for studying the process of brain development, with both scientific and clinical applications.

Basal Ganglia↗
PubMedDate not supplied

Spatial patterns of the vacuolation in subcortical white matter in sporadic Creutzfeldt-Jakob disease (sCJD).

OBJECTIVE: To study the spatial patterns of the vacuolation ("spongiform change") in the subcortical white matter in the "classical" form of sporadic Creutzfeldt-Jakob disease (sCJD). MATERIAL: Frontal, parietal, occipital and temporal lobes of 11 cases of sCJD. METHOD: Spatial patterns were studied across the white matter at the base of the gyri using spatial pattern analysis. RESULTS: In the white matter of all gyri studied, vacuoles were aggregated into clusters, 50 to > 800 microm in diameter and in 22/37 (59%) of gyri, the clusters of vacuoles exhibited a regular distribution across the base of the gyri. In the remaining gyri, the vacuoles were aggregated into large clusters, at least 400 microm or 800 microm in diameter, but without evidence of a regular distribution. In a significant proportion of gyri, the spatial patterns of the vacuolation were similar to those reported previously for spongiform change and prion protein (PrP) deposits in the corresponding grey matter. CONCLUSIONS: Degeneration of the white matter and the formation of clusters of vacuoles may occur before the degeneration of the grey matter or could be a consequence of pathology affecting the cortico-cortical pathways.

Aged↗
PubMed2003

Cavernous carotid artery calcification and white matter ischemia.

BACKGROUND AND PURPOSE: The relevance of cavernous carotid artery calcification on unenhanced CT scans of the brain has recently been investigated against the backdrop of the widespread implementation of coronary artery calcification scoring. We sought to determine whether the degree of cavernous carotid artery calcification correlated with scores of white matter hyperintensity seen on MR images. In so doing, we sought to establish a relative risk for future stroke on the grade of carotid calcification. METHODS: Neuroradiologic findings in 187 patients who underwent CT and MR imaging examinations within 1 month of each other were retrospectively reviewed. The degree of circumferential calcification and thickness of calcification were graded for the cavernous carotid arteries on the basis of CT findings. Using the scale developed by the Cardiovascular Health Study, the white matter was graded for degree of disease on the basis of MR findings. Correlation tests and regression analyses were performed to determine the impact of age, race, and sex on results. RESULTS: Although the cavernous carotid calcification scores and the MR imaging white matter scores showed good correlation (P <.001), the effect was mediated by age. With age factored in as a covariant, no correlation was shown between CT calcification scores and MR imaging white matter scores. Sex had no effect, but African American study participants had worse MR imaging white matter scores than did white participants. CONCLUSION: After adjusting for age, cavernous carotid calcification grades and MR imaging white matter scores do not show a significant correlation. The relative risk for future stroke cannot be predicted from cavernous carotid calcifications.

Adult↗
PubMedDate not supplied

Can nonenhancing white matter lesions in cancer patients be disregarded?

PURPOSE: To assess the risks and implications of assuming that white matter lesions in cancer patients that do not enhance with gadopentetate dimeglumine (Gd-DTPA) can be considered to be benign. METHODS: Gd-DTPA was administered prospectively to 131 consecutive patients with biopsy-proved extracranial malignancies referred for cranial MR imaging to exclude cerebral metastases over a 21/2-year period. From this initial group, 50 patients were identified who had focal nonenhancing lesions of the white matter on T2-weighted images, but no other findings to suggest metastatic disease. This cohort of 50 patients was then followed for at least 1 year to determine the risk and clinical implications of assuming these nonenhancing white matter lesions were benign. RESULTS: Thirty patients (60%) were alive and clinically free of cranial metastatic disease at least 1 year following their initial MR study (median follow-up time, 17 months). Twenty of the 50 patients (40%) died within 1 year of their study (median survival, 4.1 months). Review of clinic notes and hospital charts revealed no evidence for deterioration of neurologic status in any of these patients before death, and the cause of death in each case was ascribed to extracranial complications of their systemic malignancies. Eight of these 20 patients who expired had at least one follow-up cranial CT or MR scan before death showing no new cerebral metastases or change in the nonenhancing white matter lesions previously identified. In a single patient, however, follow-up MR scan revealed conversion of one of her several white matter lesions from nonenhancing to enhancing without appreciable change in its size on T2-weighted images. Unfortunately, this patient died 4 months later from surgical complications without interval change in her neurologic status nor pathologic proof of the nature of this lesion. CONCLUSIONS: White matter lesions in cancer patients that do not enhance with Gd-DTPA at the time of the initial MR study have a low probability of representing metastatic disease. Clinical management or final outcome will not likely be altered by assuming such lesions are benign.

Adult↗
PubMed2003

[Experimental study on cerebral white matter damage in neonatal rat after intrauterine Escherichia coli infection].

OBJECTIVE: To investigate the expression of glial fibrillary acidic protein (GFAP), GFAP mRNA and interleukin-1beta mRNA (IL-1beta mRNA), tumor necrosis factor-alpha mRNA (TNF-alpha mRNA) in neonatal rat brain after intrauterine infection. METHODS: Escherichia coli (E. coli) was inoculated into both uterine horns of pregnant rats when gestation was 70% complete (15 days). The control group was treated with normal saline. The pups were killed on the postnatal day 1 (P1), P3 and P7, respectively. The cerebral white matter damage of the neonatal rats was determined by HE staining. Immunohistochemistry was used for evaluation of GFAP expression in neonatal rat brains and RT-PCR to analyze GFAP mRNA, IL-1beta mRNA and TNF-alpha mRNA expression at P1, P3 and P7. RESULTS: The major histopathological changes in neonatal cerebral white matter at P7 after intrauterine infections were: weak staining of cerebral white matter and focal rarefaction. GFAP-positive cells were observed in both the control and the E. coli-treated groups. The numbers of GFAP-positive cells of the E. coli-treated group pups were markedly increased in periventricular white matter and hippocampus at P7 compared with those of the control group (periventricular white matter: 9.73 +/- 3.55 vs 5.67 +/- 1.90, P < 0.05 and hippocampus: 7.81 +/- 3.61 vs 2.16 +/- 1.11, P < 0.05, respectively). No significantly different levels of GFAP expression in corpus callosum were found between two groups (P > 0.05). The expression of GFAP mRNA in brain of the E. coli-treated neonatal rat was higher than the control at P1, P3 (P1: 0.25 +/- 0.07 vs 0.15 +/- 0.08, P < 0.05 and P3: 0.50 +/- 0.09 vs 0.39 +/- 0.08, P < 0.05, respectively), but the expression of GFAP mRNA in brain of the neonatal rat at P7 had no significant difference between two groups (P > 0.05). The expression of IL-1beta mRNA and TNF-alpha mRNA in brain of the E. coli-treated neonatal rat were higher than of the control at P1 (IL-1beta mRNA: 0.83 +/- 0.19 vs 0.50 +/- 0.30, P < 0.05 and TNF-alpha mRNA: 0.74 +/- 0.30 vs 0.30 +/- 0.20, P < 0.05, respectively), but the expression of IL-1beta mRNA and TNF-alpha mRNA in brain of the neonatal rat at P3 and P7 had no significant difference between two groups (P > 0.05). CONCLUSIONS: The intrauterine infection could cause neonatal white matter damage and IL-1beta, TNF-alpha may be a mechanism mediating between the two events.

Animals↗
PubMed2004

[The effect of aging on the apparent diffusion coefficient of normal appearing white and gray matter].

PURPOSE: To test if the apparent diffusion coefficient (ADC) values reflect the ultrastructural changes of normal appearing white and gray matter with advancing age. MATERIALS AND METHODS: We selected 45 patients with normal MRI and DW imaging findings. DW and MRI imaging was performed and for each patient the average ADC on trace images of the frontal and occipital white matter and the thalamus were compared with increasing patient age. RESULTS: The average ADC value was 0.753+/-0.054 x 10-3 mm2/sec in frontal white matter, 0.673+/-0.085 x 10-3 mm2/sec in occipital white matter, and 0.763+/-0.063 x 10-3 mm2/sec in the thalamus. For white matter, ADC values increased with advancing age. Although ADC tended to increase with age, comparison of individual thalamic ADC and patient ages did not reach statistical significance. CONCLUSION: Advancing age is associated with a small but statistically significant increase of water diffusibility in human white matter. This increase may reflect mild structural changes with normal aging.

Adolescent↗
PubMed2004

Observations on carbon and nitrogen content of suspended matter in a headwater stream in Hong Kong.

The total carbon(C) and total nitrogen(N) content of suspended matter in a small undisturbed headwater drainage basin in the New Territories of Hong Kong has been monitored. Mean C and N contents were 12.85% and 0.99% respectively for 132 samples. Samples collected under stableflow conditions had mean C and N contents of 12.81% and 1.06% respectively. Stormflow samples had mean C and N values of 12.86% and 0.97% respectively, which were very similar to the levels observed under stableflow conditions. The mean C:N ratios of 12.47 and 13.39 for stableflow and stormflow also reveal little difference according to hydrologic conditions. When all the data is considered little difference is observed in C and N according to the season. However, in winter there is a significant difference in C and N content between stable and stormflow samples. When C and N are plotted against water level the scattergraphs suggested that as stage increases the percentage of C and N in the suspended matter declines. Scattergraphs of C and N against suspended sediment concentration reveal a negative association. Comparison has been made between fresh leaf C, N and C/N ratio for trees and shrubs and the suspended matter. Fresh leaves do not appear to contribute significantly to suspended matter. The C/N ratio of suspended matter would also seem to exclude woody material and algae as sources of suspended matter.

Carbon↗
PubMed1992

Postnatal white matter necrosis in preterm infants.

One hundred twenty-seven infants less than 36 weeks of gestation (mean +/- SE = 31 +/- 3.2 weeks) were studied with echoencephalography to determine the incidence and complications associated with white matter necrosis. Ten infants (8%) developed cysts ten or more days after birth, indicating postnatal onset of white matter necrosis. Univariate analysis showed that postnatal white matter necrosis was significantly associated with maternal infection (other than urinary infection), respiratory distress syndrome, and longer requirement of an oxygen concentration greater than 40%. Forward logistic regression analysis showed postnatal white matter necrosis to be associated with maternal infection, chronic placental infarction, congenital pneumonia, and longer requirement of an oxygen concentration greater than 40%. Neurodevelopmental outcome was abnormal during infancy in 4 of the 6 survivors with postnatal white matter necrosis. Severe respiratory disease and maternal and/or fetal infection appear to increase the risk of the immature brain to white matter necrosis, predisposing the infants to subsequent neurodevelopmental delay.

Echoencephalography↗
PubMed2005

[Analysizing and quantitatively evaluating the organic matter source at different ecologic zones of tidal salt marsh, North Jiangsu Province].

The indicators including TOC, TN, C/N, delta 13C and delta 15N of surface sediments, core sediments and plants of tidal salt marshes in North Jiangsu Province are analysized.Subsequently, distribution regularities of these measurement indicators are discussed, and the biogeochemistry processes between sediments and plants are also analysized. Lastly, the organic matter sources of different ecologic zones in tidal salt marsh are evaluated, and the organic matter accumulations in different ecologic zones induced by their plants are also compared. The results indicate that TOC, TN, C/N and delta 13C show obviously zonal distribution. The organic matter sources are dominated by marine input in silt flat, Artemisia schrenkiana flat, and the transition zone between silt and Spartina alterniflora flat, and controlled by terrigenous input in Spartina alterniflora flat. Spartina alterniflora plays an important role in the accumulation of organic matter in the whole tidal salt marshes ecosystem. In study area, the annually increased TOC, organic matter and TN in Spartina alterniflora flat, Artemisia schrenkiana flat and reed flat respectively reach 6 451t, 16 595t and 536t. The amount of TOC, organic matter and TN accumulated in Spartina alterniflora flat are more than those in other ecological zones, which show that the Spartina alterniflora flat exert nonreplaceable effect on the material cycle and exchange in the whole tidal salt marshes ecosystem.

Carbon Isotopes↗
PubMed2006

Brain white-matter volume loss and glucose hypometabolism precede the clinical symptoms of Huntington's disease.

UNLABELLED: We studied the anatomic and functional changes in various brain areas during the course of Huntington's disease (HD) in a large cohort of mutation-positive individuals (n = 71) encompassing the complete range of disability (presymptomatic through stage V), and in healthy controls, for the purpose of defining both degenerative and dysfunctional brain changes in the same subjects. METHODS: We used an MRI and unsupervised multiparametric segmentation procedure based on a relaxometric approach to measure in vivo brain volumes in 71 subjects with presymptomatic to advanced HD. The same population was evaluated by 18F-FDG PET to assess variations in brain glucose metabolism. To predict age at onset in unaffected mutation carriers, we considered the estimated number of years from each subject's age to manifested HD symptoms, for a given expanded triplet number. RESULTS: Age-adjusted analyses confirmed that the 71 subjects as a group, as well as the subgroup of 24 unaffected presymptomatic subjects at risk for HD, had significantly smaller gray-matter and white-matter volumes and larger cerebrospinal fluid volumes than did controls (P < 0.0001). In the 24 presymptomatic subjects, we observed a significant inverse linear correlation between white-matter volume reduction and the estimated time to symptom onset (r2= 0.39; P = 0.0011). Both clinically unaffected subjects at risk for HD and symptomatic patients had significantly decreased glucose uptake in the cortex (frontal and temporal lobes) and striatum (caudate and putamen). HD subjects who were followed up longitudinally showed progressive white-matter reduction in the preclinical subjects (n = 10) and decreased glucose uptake in the cortex and striatum in affected (n = 21) and preclinical (n = 10) subjects. CONCLUSION: White-matter volume loss may precede gray-matter atrophy and may be associated with neuronal dysfunction in early disease.

Adult↗
PubMed2006

[Brain white matter lesions of children with phenylketonuria before and after treatment].

OBJECTIVE: To observe brain white matter changes in children with late-treated phenylketonuria (PKU) before and after receiving treatment. METHODS: This study included 19 PKU patients (aged 34-410 weeks) who were administered a low-phenylalanine diet (< 15-50 mg/kg daily) for 8-16 months. The brain MR imaging with spin-echo T1-weighted and T2-weighted sequences in coronal and axial planes was taken before and after treatment. The white matter abnormalities (T2WI high signal intensity) were graded based on the Thompson grading system. Meanwhile the intelligence quotient (IQ) or developmental quotient (DQ) was tested by the Gesell's Intelligence Scale. RESULTS: All 19 PKU patients presented with the brain white matter lesions, manifesting abnormally high T2-signal intensity in the periventricular region around anterior and posterior horns of both lateral ventricles. Different extents of mental retardation were also observed in the 19 patients. The low phenylalanine diet treatment decreased the average grade of abnormal T2-signal intensity from 2.59 to 1.76 (P < 0.05). The mean IQ or DQ improved from 44.8 to 61.6 after treatment (P < 0.05). There was some correlation between the amelioration of brain white matter lesions and IQ or DQ. CONCLUSIONS: The patients with late-treated PKU have a higher occurrence of the brain white matter lesions and mental retardation. A low-phenylalanine diet treatment can partly improve the abnormalities. Brain white matter lesions may play a part in mental retardation.

Brain↗
PubMed2006

[Protective effects of allopurinol on white matter damage in premature rats].

OBJECTIVE: To investigate the protective effects of allopurinol (ALLO) on white matter damage in premature rats. METHODS: An animal model for white matter damage was established by bilateral carotid artery occulation (BCAO). Eighty-four newborn SD rats (1 day old) were used in this study and were divided randomly into three groups [sham surgery (Sham); BCAO group (BCAO); allopurinol-treated group (ALLO)]. Pathological changes were studied 7 days and 14 days after BCAO, respectively. Myelin basic protein (MBP) was detected by immunohistochemistry 7 days and 14 days after BCAO, respectively. MBP-mRNA expression was determined 7 days and 14 days after BCAO respectively by reverse transcription-polymerase chain reaction (RT-PCR) with fluorescent quantitative method. RESULTS: In BCAO group, mild or severe rarefaction was found in 10 cases in the corpus callosum area, especially at the cingulum. Pathological changes of white matter were found in 4 cases in internal capsule. Subcortex white matter rarefaction was found in 8 cases. The extent of white matter rarefaction in ALLO group was reduced significantly. Enlargement of bilateral ventricles was found in 6 of 8 cases in BCAO group. The average ventricle size in ALLO group (2.44 +/- 0.71)% was reduced significantly as compared with that in BCAO group (3.27 +/- 0.73)% (P < 0.05). Strong MBP positive staining was found in sub-cortex, corpus callosum, hippocampus gyrus, and internal capsule of P14 sham surgery group. In BCAO group the MBP staining extent was reduced. The extent of MBP staining of ALLO group was between the other two groups. The optical density (OD) of MBP positive staining in BCAO group (6.60 +/- 0.68) was found higher than that in sham surgery group (9.40 +/- 0.53), the difference was statistically significant (P < 0.05). Compared with BCAO group, OD value in ALLO group (7.10 +/- 0.18) increased significantly (P < 0.05). RT-PCR data showed that MBP-mRNA copies (log10) in P7 and P14 rats of both BCAO and ALLO groups were lower than that in sham surgery group (P < 0.01); However, MBP-mRNA copies in ALLO group were higher than that in BCAO group (P < 0.05). CONCLUSIONS: BCAO could be used in newborn rats (1 day old) to establish a premature white matter damage (WMD) animal model. Allopurinol may have a potential protective effect on premature SD rat with ischemic WMD.

Allopurinol↗
PubMed1990

[Does circumscribed ischemic white matter lesion produce neuropsychological symptoms?].

In order to determine a possible role of ischemic white matter lesion in producing neuropsychological symptoms, we conducted a retrospective survey. Subjects were 206 consecutive patients who had been admitted to our neurology service under the diagnosis of ischemic stroke from April 1988 to November 1989 and had received brain CT as well as SPECT scans. From this cohort only patients that had circumscribed white matter lesion on CT scans were selected. Patients who had lesion in basal ganglia or thalamus were rigidly excluded. Eight subjects (3.9%) fulfilled above criteria, i.e. 5 with left hemispheric, 2 with right hemispheric and 1 with bilateral white matter lesions. Then we supplemented MRI information which had happened to be available for all the eight subjects. Exclusion of grey matter lesion based on MRI reduced the number of cases with exclusive white matter lesion into 4, i.e. 3 with left hemispheric and 1 with right hemispheric lesion. Of these, only one case with a discrete lesion in the genu of the left internal capsule had manifested mild neuropsychological impairments in naming, comprehension and writing. I123 amphetamine SPECT study revealed low uptake in the anterior half of the left middle cerebral artery in this case. We conclude that the role of a circumscribed white matter lesion as a cause of neuropsychological symptom seems to be much less clear than has been postulated.

Adult↗
PubMedDate not supplied

SPECT evaluation of simulated white matter lesions: experimental study using a brain phantom.

An experimental study using a brain phantom was performed to evaluate the detectability of simulated white matter lesions on two types of single photon emission computed tomography (SPECT) systems. A ring-type SPECT system with high spatial resolution was able to demonstrate these lesions in the white matter, while a widely used general-purpose single-head rotating gamma camera failed to show them. The detectability of white matter lesions was decreased by photons scattered from the highly radioactive gray matter and the poor spatial resolution of the SPECT system. In order to improve the detectability of white matter lesions it is important to apply scatter correction and improve the spatial resolution of the SPECT system. Brain phantom studies made it easier to interpret white matter lesions that were difficult to interpret on the basis of clinical images alone, and the knowledge acquired from the brain phantom study will contribute to the interpretation of clinical images.

Brain↗
PubMed1991

[MRI of white matter pathways].

CT scan shows some relatively large white matter pathways such as corpus callosum or internal capsule, while MRI provides more sophisticated display of cerebral white matter pathways, based partly on difference in the water content, which improves contrast resolution of structures that cannot be appreciated on CT scanning. The white matter shows slightly high signal intensity in T1WI as compared with the peripheral gray matter. In contrast, it is relatively low signal intensity in long TR sequence. The signal intensity is correlated with myelination, density of myelin fibers and possibly iron deposition. In this study, we collected data on 30 patient, aged from 3 to 60 years average 38 years of normal MRI study of the brain. We routinely obtained T1 Weighted image (T1WI, TR/TE 500-600/20 msec), dual echoes image of proton density image (PDI, TR/TE 2000-3000/20 msec), T2 weighted image (T2WI, TR/TE 2000-3000/80-120 msec), in axial and coronal sections. In some cases sagittal section was also imaged. We identified the white matter pathways based on the data from the axial and coronal sections of 2 autopsy specimens. We also consulted several textbooks and literature reviews of gross and MRI anatomy. The following white matter pathways could be clearly observed on MRI: 1. Projection fibers: corona radiata and internal capsule; 2. Commissural fibers: corpus callosum and anterior commissure; 3. Associated fibers: superior occipito-frontal fasciculus, superior longitudinal fasciculus, ucinate fasciculus, cingulum bundle, optic radiation fornix and mammillothalamic tract.

Adolescent↗