Jin-Suh Kim | Search PubMed

PubMed2005

Diffusion tensor imaging in schizophrenia.

BACKGROUND: Diffusion tensor imaging (DTI) is a relatively new neuroimaging technique that can be used to examine the microstructure of white matter in vivo. A systematic review of DTI studies in schizophrenia was undertaken to test the hypothesis that DTI can detect white matter differences between schizophrenia patients and normal control subjects. METHODS: EMBASE, PubMed, Medline, and PsychInfo were searched online and key journals were searched manually for studies comparing anisotropy (a measure of white matter integrity) between patients and control subjects. Nineteen articles were systematically reviewed. RESULTS: Though 16 studies found differences, methodological and data differences prevented a meta-analysis. Fourteen studies found reduced anisotropy in patients; two studies found only a loss of normal asymmetry. The region of investigation varied across studies, however, and when the same region (for example, the cingulum) was examined in different studies, as many failed to find a difference as found one. These inconsistencies may be the result of small sample sizes and differences in methodology. CONCLUSIONS: Diffusion tensor imaging has yet to provide consistent findings of white matter abnormalities in schizophrenia. Its potential as a means of examining anatomical connectivity may be realized with the study of larger, more homogenous groups of subjects and with ongoing improvements in image analysis.

Adult↗

PubMed2004

Functional MRI study of a serial reaction time task in Huntington's disease.

The aim of this study was to investigate pathophysiological changes at an early stage of clinical Huntington's disease (HD) using a functional magnetic resonance imaging (fMRI) study and a serial reaction time task paradigm. Mildly affected and presymptomatic HD subjects (n = 8) and healthy normal controls (NC, n = 12) were studied. A group behavioral effect of implicit learning was seen only in the control population. Individual statistical parametric mapping (SPM) analysis showed more consistent activation of the caudate nucleus and putamen in the NC group. In the HD group, the group average SPM showed significant activation in the right head of caudate nucleus, as well as bilateral thalami, left middle temporal, right superior temporal, right superior frontal, right middle and inferior frontal and right postcentral gyri. In the comparison of between-group differences (NC-HD), reduced activation in the HD group relative to NC was observed in the right middle frontal, left middle occipital, left precuneus, and left middle frontal gyri. The variable striatal activity in the Huntington's group suggests early functional loss possibly associated with previously demonstrated early atrophy of these same neural structures.

Adult↗

PubMed2002

Using relative cerebral blood flow and volume to evaluate the histopathologic grade of cerebral gliomas: preliminary results.

OBJECTIVE: Relative cerebral blood flow has rarely been studied as part of the preoperative assessment of tumor grade, although relative cerebral blood volume is known to be useful for this assessment. The purpose of our study was to determine the usefulness of relative cerebral blood flow in assessing the histopathologic grade of cerebral gliomas. SUBJECTS AND METHODS: MR imaging was performed in 17 patients with proven cerebral gliomas (11 high-grade gliomas and six low-grade gliomas), using a first-pass gadopentetate dimeglumine-enhanced T2-weighted echoplanar perfusion sequence. The perfusion data were deconvoluted with an arterial input function, using singular value decomposition to obtain a color map of relative cerebral blood volume and flow; the relative cerebral blood volume and flow ratios were expressed relative to values measured in the contralateral white matter. The Wilcoxon's rank sum test was performed to test the difference between the mean of the relative cerebral blood volume (or flow) ratio in high-grade gliomas and that in low-grade gliomas. Receiver operating characteristic curve analysis was used to evaluate the association between the relative cerebral blood volume (or flow) ratio and the grade of the glioma, as well as to calculate the relative cerebral blood volume and flow ratio cutoff value permitting discrimination between high- and low-grade gliomas. The correlation between relative cerebral blood volume and flow ratios was evaluated using Spearman's rank correlation analysis. We also made a qualitative assessment regarding the match or mismatch of areas of maximal contrast enhancement with the areas of highest color perfusion maps. RESULTS: The mean of the relative cerebral blood volume ratio was 4.91 in the high-grade gliomas and 2.00 in the low-grade gliomas. The mean relative cerebral blood flow ratio was 4.82 in the high-grade gliomas and 1.83 in the low-grade gliomas. A significant difference in each relative cerebral blood volume and flow ratio was found between the high- and low-grade gliomas (Wilcoxon's rank sum test, p < 0.05). Both the relative cerebral blood volume and flow ratios strongly matched the grade of the glioma, but the difference between the two areas was not significant (receiver operating characteristic curve analysis, p > 0.05). The desired cutoff value was 2.93 in the relative cerebral blood volume ratio and 3.57 in the relative cerebral blood flow ratio. Additionally, there was a strong correlation between the relative cerebral blood volume and flow ratios (Spearman's rank correlation coefficient = 0.762; p < 0.05). There was frequent mismatch (33%) between the qualitative assessment of the contrast-enhanced T1-weighted MR images and the perfusion maps. CONCLUSION: First-pass gadopentetate dimeglumine-enhanced T2-weighted echoplanar perfusion MR imaging is useful for the preoperative assessment of tumor grade. A relative cerebral blood flow ratio, in addition to a relative cerebral blood volume ratio, can be a useful tool in the evaluation of the histopathologic grade of cerebral gliomas.

Adolescent↗