Biomedical subjects

Hitoshi Matsuzawa

Publications and source records attributed to Hitoshi Matsuzawa.

7 recordsLinked to original sources

PubMed2005

Diffusion tensor analysis in chronic schizophrenia. A preliminary study on a high-field (3.0T) system.

The objective of this study was to delineate further the nature of diffusion anisotropy abnormalities in frontal white matter previously observed in schizophrenic patients using a high-field magnetic resonance imaging (MRI) system. Six schizophrenia patients and six healthy control subjects were examined using a highfield MRI (3.0T) system. In order to confirm previously reported abnormalities in anisotropy, data were first analyzed to determine fractional anisotropy (FA), a frequently utilized general index of anisotropy. Subsequently, the identical data set was subjected to lambda chart analysis (LCA), a newly developed algorithm for diffusion tensor analysis (DTA) that more effectively provides eigenvalue information. Frontal white matter FA was found to be significantly reduced in schizophrenic patients compared to control subjects, confirming previously reported findings. LCA revealed that the decline in FA was due to a disproportionate increase in small eigenvalue components, and not due to a decline in principal eigenvalue components.

Adult↗

PubMed2005

Isotropic component trace analysis.

A new method for analyzing diffusion tensor imaging (DTI) of the brain, based on a recently introduced algorithm, lambda chart analysis (LCA), is presented. Pre-treatment of a given DTI data set with LCA, which effectively segregates isotropic and anisotropic components, allows for total removal of the anisotropic component from the DTI data set. The remaining pure isotropic component can therefore be subjected to further analysis similar to that applied in the trace histogram method. Deconvolution of the trace function yielded 3 Gaussian elements. Remapping of these 3 deconvoluted isotropic elements back onto the 2-dimensional image plane provided anatomical correlates of each element. The algorithm, referred to here as isotropic component trace analysis, can be used as a pictorial analytic tool, as well as a numerical analytical tool, for the noninvasive assessment of isotropic parenchymal components. The presented method provides quantitative indices of certain parenchymal parameters with better clarity than currently available methods. A ready-to-use program, EZ-LCA, for this powerful method is provided (available at http://coe.bri.niigata-u.ac.jp).

Algorithms↗

PubMed2005

Diffusion tensor analysis of peritumoral edema using lambda chart analysis indicative of the heterogeneity of the microstructure within edema.

OBJECT: Histopathological studies indicate that cerebral edema associated with tumors (peritumoral edema) does not represent a single pathophysiological or clinical entity. In this study the authors investigated peritumoral edema by performing lambda chart analysis (LCA), a noninvasive technique that can be used to make visible and analyze apparent water diffusivity in tissues in vivo, and assessed the utility of LCA in differentiating high-grade gliomas from nonglial tumors. METHODS: The water diffusivity characteristics of peritumoral edema associated with four tumor groups-12 high-grade gliomas, five low-grade gliomas, 11 metastatic tumors, and 15 meningiomas-were assessed in 43 patients by performing magnetic resonance imaging with the aid of a 3-tesla magnetic resonance imaging system. In all tumor groups, peritumoral edema exhibited greater trace values and reduced anisotropy compared with normal white matter. Edema associated with high-grade gliomas had significantly higher trace values than edema associated with the other three tumor groups, although the anisotropic angles of those groups were comparable. CONCLUSIONS: Lambda chart analysis identified two distinct types of peritumoral edema: edema associated with high-grade gliomas and edema associated with low-grade gliomas or nonglial tumors. The apparent water diffusivity was significantly greater in high-grade gliomas, whereas the anisotropy in these lesions was comparable to that of edema in other tumors. These findings indicated that water movement in areas of edema, predominantly in the extracellular spaces, was less restricted in high-grade gliomas, a phenomenon that likely reflected the destruction of the extracellular matrix ultrastructure by malignant cell infiltration and consequently greater water diffusion. Although preliminary, this study indicates that LCA could be used as a clinical tool for differentiating high-grade gliomas and for evaluating the extent of cellular infiltration.

Adolescent↗

PubMed2003

All-phase MR angiography using independent component analysis of dynamic contrast enhanced MRI time series: phi-MRA.

Dynamic contrast enhanced magnetic resonance imaging (dynamic MRI) represents a MRI version of non-diffusible tracer methods, the main clinical use of which is the physiological construction of what is conventionally referred to as perfusion images. The raw data utilized for constructing MRI perfusion images are time series of pixel signal alterations associated with the passage of a gadolinium containing contrast agent. Such time series are highly compatible with independent component analysis (ICA), a novel statistical signal processing technique capable of effectively separating a single mixture of multiple signals into their original independent source signals (blind separation). Accordingly, we applied ICA to dynamic MRI time series. The technique was found to be powerful, allowing for hitherto unobtainable assessment of regional cerebral hemodynamics in vivo.

Aged↗

PubMed2003

Absolute eigenvalue diffusion tensor analysis for human brain maturation.

The absolute eigenvalues of the diffusion tensor of white matter in sixteen normal subjects in two groups representing the early developmental stage (ages 1-10 years, n=8) and young adult stage (ages 18-34 years, n=8) were assessed using a high-field (3.0 T) magnetic resonance (MR) system. All three eigenvalues, including the largest eigenvalue, decreased significantly with brain maturation. The rate of the decline in the two small eigenvalues was, however, much higher than that of the largest eigenvalue, resulting in an actual increase in fractional anisotropy, a commonly measured relative index. The data demonstrate that an increase in anisotropy associated with brain maturation represents a significant decline in the small eigenvalue components, rather than an increase in the largest eigenvalue. The observed pattern of eigenvalue changes is best explained by the simultaneous occurrence of two of several independent phenomena within the axonal microenvironment during the myelination process, namely, (1) decline in unrestricted water content in extra-axonal space, and (2) increase in apparent diffusivity within the axon.

Adolescent↗

PubMed2003

Feasibility study of single region lambda chart analysis for pyramidal tract physiology.

Diffusion characteristics of the pyramidal tract were assessed in nine patients who had clinical evidence of pyramidal tract dysfunction, utilizing lambda chart analysis (LCA). The underlying pathologic process of tract dysfunction was varied and included Pelizaeus-Merzbacher disease (PMD), Alexander disease, adrenoleukodystrophy (adrenomyeloneuropathy (AMD) type and cerebral type), amyotrophic lateral sclerosis (ALS), and Wallerian degeneration (WD). While pyramidal tract diffusion characteristics in WD indicated a pathological process characterized by replacement of normal fibers by smaller cellular component such as degenerated small fibers and/or gliosis, pyramidal tract diffusion characteristics in patients with PMD, Alexander disease, and adreno leukodystrophy of the cerebral type indicated a pathological process characterized by replacement of normal fibers by larger cellular components such as spheroids or edematous space. Pyramidal tract diffusion characteristics of patients with ALS or adrenoleukodystrophy of AMD type were relatively intact suggesting a pathological process characterized by relatively preserved structural architecture. These findings are highly consistent with known pathophysiological indices and indicate the feasibility of the clinical utility of LCA for assessing pyramidal tract physiology.

Adolescent↗

PubMed2002

Evaluation of efficacy of an automated single-voxel proton MRS algorithm on a 3T system.

PURPOSE: To evaluate the efficacy of a fully automatic, single-voxel, proton MR spectroscopy algorithm on a 3.0T MR system. METHODS: The PROBE/SVQ algorithm (GE Medical Systems) was evaluated on a General Electric (GE) Signa LX-3T system. Ten normal volunteers (female, 21.1+/-2.0 years old) participated in the study. Nine representative regions of interest were examined, namely, right and left frontal white matter; right and left parietal white matter; right and left basal ganglia; right and left dentate nucleus; and pons. RESULTS: The mean coefficients of variation in all regions for the N-acetyl-aspartate to creatine ratio (NAA/Cr), choline to creatine ratio (Cho/Cr), and choline to N-acetyl-aspartate ratio (Cho/NAA) were 10.2+/-2.4%, 11.4+/-3.2% and 12.6+/-1.4%, respectively. CONCLUSION: A fully automated spectroscopic examination under clinical setting utilizing the PROBE/SVQ algorithm appears to be a reliable method, extending the window of routine clinical assessment of brain metabolism.

Adult↗