Biomedical subjects

Yoshitaka Okuhata

Publications and source records attributed to Yoshitaka Okuhata.

4 recordsLinked to original sources

PubMed2004

Semiquantitative assessment of myelination using magnetic resonance imaging in normal fetal brains.

OBJECTIVES: To evaluate the development of myelination in normal fetuses quantitatively using magnetic resonance (MR) imaging in relation to gestational age (GA). METHODS: Fetal MR images were obtained from 101 fetuses between 26 and 39 weeks of gestation with no neurological problems. Regions of interest were designated in frontal lobe, corona radiata, optic radiation, thalamus, pons, cerebellar vermis, and vitreous body. The signal intensity ratio (SIR) was calculated by the signal intensity of each of these designated areas to that of the vitreous body and analyzed in relation to GA. RESULTS: The SIR of the frontal lobe did not vary significantly with GA. The SIR of the corona radiata and the optic radiation decreased significantly with GA (P < 0.05); after 34 weeks of gestation, they decreased sharply. The SIR of the thalamus, the pons, and the cerebellar vermis was significantly smaller than that of the cerebral white matter at 26 weeks of gestation (P < 0.05) and decreased significantly with GA (P < 0.05). CONCLUSION: Changes in the SIR approximately corresponded to the time-course of progression of myelination in the previous histopathological reports. Semiquantitative evaluation on MR images may allow prenatal diagnosis of a delay or deficit of myelination.

Brain↗

PubMed2003

Assessment of cortical gyrus and sulcus formation using MR images in normal fetuses.

OBJECTIVES: The purpose of this study was to estimate the development of the gyrus and sulcus formation in normal fetuses on the basis of the neuroanatomical findings using MR images in relation to gestational age. METHODS: The MR images were obtained from 109 normal fetuses from 18 to 39 weeks of gestation with no neurological problems. The MR images were classified into 8 stages of development for the gyrus and sulcus formation in the frontal and temporal lobes on the basis of the neuroanatomical findings reported by Chi et al. (1977) and Dorovini-Zis and Dolman (1977). We examined retrospectively the relationship between our classification and gestational age in comparison with the five-stage classification proposed by McArdle et al. (1987). RESULTS: There were significant differences in the gestational age among the 8 groups (P < 0.001). Multiple comparison of individual groups revealed significant differences in the gestational age among the groups (P < 0.05). Images from 28 to 34 weeks of gestation were classified into 4 stages in our classification, while being covered by one stage in McArdle's classification. CONCLUSION: Our classification is useful for the assessment of fetal cerebral maturation during the third trimester of pregnancy and may contribute to the prenatal diagnosis of developmental delay of the gyrus and sulcus formation.

Cerebral Cortex↗

PubMed2003

[A central nervous system lupus showing peculiar findings on cranial magnetic resonance imaging (MRI)].

We report a case of central nervous system (CNS) lupus showing peculiar findings on cranial magnetic resonance imaging (MRI) with remarkable improvement after corticosteriod therapy. The patient was a 28-year-old woman, admitted to our hospital with severe fever, general malaise, and facial edema on June 4, 2001. After admission, she was diagnosed with systemic lupus erythematosus (SLE). On June 6, she showed diplopia at a distance, and on June 10, she suddenly became unconscious and developed general convulsions. Cranial MRI showed asymmetrical, multifocal, high signal intensity lesions on T2-weighted image (T2-WI) and low signal intensity on T1-weighted image (T1-WI). These lesions were primarily present in the subcortical white matter, with some detected in the overlying cerebral cortex. Gadolinium (Gd)-DTPA enhanced T1-WI showed marked leptomeningeal enhancement overlying the lesions on T1-WI and T2-WI. Apparent diffusion coefficient image (ADCI) showed high signal intensity in the surrounding areas of the T1-WI and T2-WI lesions, and low signal intensity in the central areas of the lesions. Diffusion weighted image (DWI) showed high signal intensity in the central areas of the low signal intensity on ADCI. Cerebrospinal fluid (CSF) examination revealed albuminocytologic dissociation (cell counts of 2/microliter and protein level of 108 mg/dl). CSF IgG index was elevated to 1.152 (normal < 0.7) and interleukin-6 (IL-6) activity to 27.2 pg/ml (normal < 4.0). On June 10, Intravenous administration of high-dose methylprednisolone (1,000 mg/day for 3 days) was started to treat CNS lesions of SLE. Her CNS manifestations, CSF findings, and the lesions on the cranial MRI improved remarkably. This is the first case report describing the lesions on both ADCI and DWI in a case of CNS lupus. The findings of ADCI and DWI suggest that the lesions of high signal intensity on ADCI indicate interstitial edema caused by inflammatory microangiopathy, and the lesions of high signal intensity on DWI and low signal intensity on ADCI indicate cytotoxic edema caused by ischemic change resembling microinfarction. We speculate that in addition to usual T1-WI and T2-WI, performing ADCI and DWI is useful for understanding the pathogenesis of CNS lupus lesions, and may play a significant role in the prognosis.

Adult↗

PubMedDate not supplied

Decrease in tumor apparent permeability-surface area product to a MRI macromolecular contrast medium following angiogenesis inhibition with correlations to cytotoxic drug accumulation.

BACKGROUND: New strategies for cancer therapy include the combination of angiogenesis inhibitors with cytotoxins. However, angiogenesis inhibitors may alter tumor microvessel structure and transendothelial permeability thereby reducing tumoral delivery of cytotoxic agents. The aim of this study was to estimate quantitatively the apparent permeability-surface area product (K(PS)) in tumors to a macromolecular contrast medium (MMCM), to follow changes in K(PS) induced by antibodies to vascular endothelial growth factor (anti-VEGF), and to correlate the findings with tumor accumulation of cisplatin, a highly protein-bound cytotoxin, and 5-fluorouracil (5-FU), a small unbound cytotoxin. METHODS: Dynamic MRI enhanced with a MMCM (albumin-(Gd-DTPA)(30)) was analyzed using a two-compartment tumor tissue model (plasma and interstitial water) to quantitatively estimate K(PS). These estimates of K(PS) were correlated with cytotoxic drug accumulations in the tumors. RESULTS: Anti-VEGF treatment reduced K(PS) to MMCM in tumor tissue from 0.013 mL h(-1) cm(-3) (n = 9) at baseline to 0.003 mL h(-1) cm(-3) (n = 9) 24 h later (p <.05). The K(PS) values correlated significantly (r(2) =.78; p <.0001) with the tumor cisplatin accumulation. No correlation (r(2) =.001; p =.89) was found between K(PS) and tumor accumulation of the substantially smaller 5-FU molecule. CONCLUSIONS: MMCM-enhanced MRI can be used to detect and estimate changes in K(PS) to this contrast agent following a single dose of anti-VEGF antibody. The decline in K(PS) induced by this inhibitor of angiogenesis is associated with reduced tumor concentration of a protein-bound cytotoxin, similar in molecular weight to the contrast agent. MRI assays of microvascular status as performed here may be useful to clinically monitor responses to anti-angiogenesis drugs and to optimize the choice and timing of cytotoxic drug administration.

Angiogenesis Inhibitors↗