Faculty Profiles - TAOKA Toshiaki

Paradoxical parasellar high signals resembling shunt diseases on routine 3D time-of-flight MR angiography of the brain: mechanism for the signals and differential diagnosis from shunt diseases International journal

M Sakamoto, T Taoka, S Iwasaki, H Nakagawa, A Fukusumi, K Takayama, T Wada, K Kichikawa

MAGNETIC RESONANCE IMAGING Vol. 22 ( 9 ) page： 1289 - 93 2004.11

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE INC

Background and Purpose: We occasionally encounter phenomena in which venous flow signals of the cavernous sinus (CS) and/or inferior petrosal sinus (IPS) are visualized paradoxically in patients without arteriovenous shunt in 3D time-of-flight magnetic resonance angiography (3D-TOF MRA) of the brain, The aims of this study are to examine the frequency and cause of this phenomenon ("pseudo-shunt" image) and to determine points of differentiation from definite arteriovenous shunt images ("real shunt").
Methods: We retrospectively examined 85 maximum intensity projection images obtained by MRA in the absence of arteriovenous shunts to detect pseudo-shunt images, and evaluated source images: of pseudo-shunt studies for venous structures. Four real-shunt MRA studies were compared with pseudo-shunt studies on three points: (1) extension of sinuses, (2) extension of cortical veins, and (3) signal intensity of sinuses as assessed by the scoring method (1 point when these findings exist, 0 when they do not).
Results: We detected five CS (3%) and six IPS (4%) signals in 9 (11%) of the 85 cases. In the source images of four pseudo-shunt images in the CS, we detected signals from the sphenoparietal sinus (SPS). The average score was significantly lower in the pseudo-shunt (0.22) than the real-shunt (2.75) images (P<.0001).
Conclusion: In cerebral 3D-TOF MRA, pseudo-shunt images were seen in 11% (9/85) of the study population, with antegrade upward blood flow of the SPS considered as one of the causes. Real-shunt signals can be distinguished from pseudo-shunt signals by evaluation of source images. (C) 2004 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.mri.2004.08.004

Clinically mild encephalitis/encephalopathy with a reversible splenial lesion Reviewed

H Tada, J Takanashi, AJ Barkovich, H Oba, M Maeda, H Tsukahara, M Suzuki, T Yamamoto, T Shimono, T Ichiyama, T Taoka, O Sohma, H Yoshikawa, Y Kohno

NEUROLOGY Vol. 63 ( 10 ) page： 1854 - 1858 2004.11

Language：English Publishing type：Research paper (scientific journal) Publisher：LIPPINCOTT WILLIAMS & WILKINS

Objective: To clarify whether patients with clinical diagnoses of encephalitis/encephalopathy with a reversible lesion in the splenium of the corpus callosum (SCC) share common clinical features. Methods: Possible encephalitis/encephalopathy patients with a reversible isolated SCC lesion on MRI were collected retrospectively. Their clinical, laboratory, and radiologic data were reviewed. Results: Fifteen encephalitis/encephalopathy patients with a reversible isolated SCC lesion were identified among 22 patients referred for this study. All 15 patients had relatively mild clinical courses. Twelve of the 15 patients had disorders of consciousness. Eight patients had seizures, and three of them received antiepileptic drugs. All 15 patients clinically recovered completely within 1 month ( 8 patients within a week) after the onset of neurologic symptoms. The SCC lesion was ovoid in six patients; it extended irregularly from the center to the lateral portion of SCC in the other eight patients. Homogeneously reduced diffusion was seen in all seven patients who underwent diffusion-weighted imaging. There was no enhancement in the five patients so examined. The SCC lesion had completely disappeared in all patients at follow-up MRI exams between 3 days and 2 months after the initial MRI ( within 1 week in eight patients). Conclusion: The clinical features among the affected patients were nearly identical, consisting of relatively mild CNS manifestations and complete recovery within 1 month.

Retinotopy with coordinates of lateral occipital cortex in humans International journal

T Kaido, T Hoshida, T Taoka, T Sakaki

JOURNAL OF NEUROSURGERY Vol. 101 ( 1 ) page： 114 - 8 2004.7

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER ASSOC NEUROLOGICAL SURGEONS

Object. The lateral occipital cortex in humans is known as the "extrastriate visual cortex." It is, however, an unexplored field of research, and the anatomical nomenclature for its surface has still not been standardized. This study was designed to investigate whether the lateral occipital cortex in humans has retinotopic representation.
Methods. Four right-handed patients with a diagnosis of intractable epilepsy from space-occupying lesions in the occipital lobe or epilepsy originating in the occipital lobe received permanently implanted subdural electrodes. Electrical cortical stimulation was applied directly applied to the brain through metal electrodes by using a biphasic stimulator. The location of each electrode was measured on a lateral skull x-ray study. Each patient considered a whiteboard with vertical and horizontal median lines. The patient was asked to look at the midpoint on the whiteboard. If a visual hallucination or illusion occurred, the patient recorded its outline, shape, color, location, and motion on white paper one tenth the size of, and with vertical and horizontal median lines similar to those on, the whiteboard. Polar angles and eccentricities of the midpoints of the phosphenes from the coordinate origin were measured on the paper. On stimulation of the lateral occipital lobe, 44 phosphenes occurred. All phosphenes were circular or dotted, with a diameter of approximately I cm, except one that was like a curtain in the peripheral end of the upper and lower visual fields on stimulation of the parietooccipital region. All phosphenes appeared in the visual field contralateral to the cerebral hemisphere stimulated. On stimulation of the lateral occipital lobe, 22 phosphenes moved centrifugally or toward a horizontal line. From three-dimensional scatterplots and contour maps of the polar angles and eccentricities in relation to the x-ray coordinates of the electrodes, one can infer that the lateral occipital cortex in humans has retinotopic representation.
Conclusions. The authors found that phosphenes induced by electrical cortical stimulation of the lateral occipital cortex represent retinotopy. From these results one can assert that visual field representation with retinotopic relation exists in the extrastriate visual cortex.

DOI： 10.3171/jns.2004.101.1.0114

Progressive MRI changes indicating inflammatory neurodegeneration with cognitive decline induced by ischemic stress Reviewed

M Fujinka, T Taoka, Y Matsuo, M Mishima, K Ogoshi, Y Kondo, Asano, I, M Fujiwara, T Sakaki, A Miyasaki, D Park, BK Siesjo

STROKE Vol. 35 ( 6 ) page： E323 - E323 2004.6

Distinguishing between anterior cerebral artery and middle cerebral artery perfusion by color-coded perfusion direction mapping with arterial spin labeling International journal

T Taoka, S Iwasaki, H Nakagawa, A Fukusumi, S Hirohashi, M Sakamoto, K Kichikawa, K Murata

AMERICAN JOURNAL OF NEURORADIOLOGY Vol. 25 ( 2 ) page： 248 - 51 2004.2

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER SOC NEURORADIOLOGY

The purpose of this study was to evaluate collateral circulation by describing anterior cerebral artery and middle cerebral artery perfusion areas. Pairs of image sets spin labeled on the medial and lateral side were used. A pixel-by-pixel t test was performed, with blue gradation used to display lateral perfusion (ie, middle cerebral artery) and orange gradation for anterior cerebral artery perfusion. Extensions of anterior cerebral artery perfusion areas in cases of middle cerebral artery stenosis were described. This method may aid in estimation of collateral circulation for stroke treatment.

Signal characteristics of FLAIR related to water content: comparison with conventional spin echo imaging in infarcted rat brain International journal

T Taoka, M Fujioka, Y Matsuo, M Notoya, S Iwasaki, A Fukusumi, H Nakagawa, M Sakamoto, K Kichikawa, H Ohishi

MAGNETIC RESONANCE IMAGING Vol. 22 ( 2 ) page： 221 - 7 2004.2

Language：English Publishing type：Research paper (scientific journal) Publisher：ELSEVIER SCIENCE INC

To examine the correlation between tissue water content and signal intensity on fluid-attenuated inversion recovery (FLAIR) images, we analyzed infarcted rat brain, verified the results by theoretical simulation, and compared them with conventional spin-echo images. We produced brain infarction with cavitation in five rats by middle cerebral artery occlusion. After in vivo MRI, histologic sections of the MRI plane were obtained. We measured the signal intensity of regions on FLAIR and spin-echo images, and measured the area of cavitation on histologic sections. We plotted curves of cavity percentage to signal intensity. Theoretical values were calculated using a two- compartment model. On the curve of cavity area to signal intensity, the signal on FLAIR images peaked in tissues with 20% to 30% area of cavitation. On the theoretical curve, the signal on FLAIR images peaked at 90% tissue water content. These results seem to be characteristic of FLAIR. (C) 2004 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.mri.2003.09.004

Distinguishing between anterior cerebral artery and middle cerebral artery perfusion by color-coded perfusion direction mapping with arterial spin labeling Reviewed

T Taoka, S Iwasaki, H Nakagawa, A Fukusumi, S Hirohashi, M Sakamoto, K Kichikawa, K Murata

AMERICAN JOURNAL OF NEURORADIOLOGY Vol. 25 ( 2 ) page： 248 - 251 2004.2

Language：English Publishing type：Research paper (scientific journal) Publisher：AMER SOC NEURORADIOLOGY

Distinguishing between Anterior Cerebral Artery and Middle Cerebral Artery Perfusion by Color-Coded Perfusion Direction Mapping with Arterial Spin Labeling

Taoka T., Iwasaki S., Nakagawa H., Fukusumi A., Hirohashi S., Sakamoto M., Kichikawa K., Murata K.

American Journal of Neuroradiology Vol. 25 ( 2 ) page： 248 - 251 2004.2

Language：English Publishing type：Research paper (scientific journal) Publisher：American Journal of Neuroradiology

Magnetic resonance imaging shows delayed ischemic striatal neurodegeneration

Imaging and management of acute stroke Reviewed

WC Yuh, T Taoka, T Ueda, M Maeda

DISEASES OF THE BRAIN, HEAD AND NECK, SPINE page： 20 - 26 2004

Optic Tractography in Epilepsy Surgery Reviewed

Toshiaki Taoka, Tohru Hoshida, Kimihiko Kichikawa, Toshisuke Sakaki

Nosotchu Vol. 26 ( 4 ) page： 574 - 578 2004

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Japan Stroke Society

Diffusion tensor tractography is a newly developed method for tracing tracts in white matter using combination of diffusion tensor images. We evaluate the degree of impairment of optic tracts in the cases with visual field defect after temporal lobectomy using diffusion tensor tractography. We examined 8 cases after temporal lobectomy for temporal lobe epilepsy. Visual field defect in medial sector and lateral sector of upper 1/4 visual field were evaluated. Diffusion tensor tractography of optic radiation was made from 6 axes diffusion tensor images. We evaluated the correlation between the degree of visual field defect and visualization of Meyer's loop on tractographies. Medial sector field tends to be impaired after temporallobectomy. Diffusion tensor tractography showed incomplete to no visualization of Meyer's loop in the cases with severe visual field defect. While, visualization of optic radiation was almost complete in cases with mild visual field defect. Diffusion tensor tractography was useful in evaluating post surgical changes in optic radiation. Potential usefulness of tractography in surgical planning was also suggested.

DOI： 10.3995/jstroke.26.574

CiNii Research

M Fujioka, T Taoka, Y Matsuo, K Mishima, K Ogoshi, Y Kondo, M Tsuda, M Fujiwara, T Asano, T Sakaki, A Miyasaki, D Park, BK Siesjo

ANNALS OF NEUROLOGY Vol. 54 ( 6 ) page： 732 - 47 2003.12

Language：English Publishing type：Research paper (scientific journal) Publisher：WILEY-LISS

Brief focal ischemia leading to temporary neurological deficits induces delayed hyperintensity on T1-weighted magnetic resonance imaging (MRI) in the striatum of humans and rats. The T1 hyperintensity may stem from biochemical alterations including manganese (Mn) accumulation after ischemia. To clarify the significance of this MRI modification, we investigated the changes in the dorsolateral striatum of rats from 4 hours through 16 weeks after a 15-minute period of middle cerebral artery occlusion (MCAO), for MRI changes, Mn concentration, neuronal number, reactivities of astrocytes and microglia/macrophages, mitochondrial Mn-superoxide dismutase (Mn-SOD), glutamine synthetase (GS), and amyloid precursor protein. The cognitive and behavioral studies were performed in patients and rats and compared with striatal T1 hyperintensity to show whether alteration in brain function correlated with MRI and histological changes. The T1-weighted MRI signal intensity of the dorsolateral striatum increased from 5 days to 4 weeks after 15-minute MCAO, and subsequently decreased until 16 weeks. The Mn concentration of the dorsolateral striatum increased after ischemia in concert with induction of Mn-SOD and GS in reactive astrocytes. The neuronal survival ratio in the dorsolateral. striatum decreased significantly from 4 hours through 16 weeks, accompanied by extracellular amyloid precursor protein accumulation and chronic glial/inflammatory responses. The patients and rats with neuroradiological striatal degeneration had late-onset cognitive and/or behavioral declines after brief focal ischemia. This study suggests that (1) the hyperintensity on T1-weighted MRI after mild ischemia may involve tissue Mn accumulation accompanied by Mn-SOD and GS induction in reactive astrocytes, (2) the MRI changes correspond to striatal neurodegeneration with a chronic inflammatory response and signs of oxidative stress, and (3) the subjects with these MRI changes are at risk for showing a late impairment of brain function even though the transient ischemia is followed by total neurological recovery.

DOI： 10.1002/ana.10751

Vasogenic edema and VEGF expression in a rat two-vein occlusion model.

Kimura R, Nakase H, Sakaki T, Taoka T, Tsuji T

Acta neurochirurgica. Supplement Vol. 86 page： 213 - 7 2003

Progressive MRI change indicates manganese accumulation and striatal neurodegeneration resulting in cognitive decline in humans and rats after brief focal ischemia.

Fujioka M, Taoka T, Matsuo Y, Mishima K, Ogoshi K, Kondo Y, Tsuda M, Fujiwara M, Asano T, Sasaki T, Miyasaki A, Park D, Siesj, BK

Ann Neurol Vol. 54 page： 732 - 747 2003

Vasogenic edema and VEGF expression in a rat two-vein occlusion model Reviewed

R Kimura, H Nakase, T Sakaki, T Taoka, T Tsuji

BRAIN EDEMA XII Vol. 86 page： 213 - 217 2003

Language：English Publishing type：Research paper (international conference proceedings) Publisher：SPRINGER-VERLAG WIEN

Vasogenic edema plays an important etiologic role in the pathogenesis of cerebral venous circulation disturbances (CVCDs). Since vascular endothelial growth factor (VEGF) is a major mediator in angiogenesis and vascular permeability, including induction of vasogenic edema, the present study was undertaken to investigate whether it has any relevance to CVCDs.
Male Wistar rats (n = 15) were used. Two adjacent cortical veins were occluded photochemically using rose bengal dye and fiberoptic illumination, with evaluation 24 hours thereafter by magnetic resonance imaging (MRI). Each brain was removed from the skull Immediately after MRI and processed for hematoxylin-eosin staining (H&E staining) of sections for histopathology and comparison with MRI data. VEGF expression as demonstrated immunohistochemically appeared to coincide with vasogenic edema, diagnosed as high intensity areas on apparent diffusion coefficient of water (ADCw) maps. On the basis of these data, we conclude that VEGF is related to formation of vasogenic edema in the acute stage of CVCD.

排尿日誌を利用してスクリーニングした夜間多尿例における視床下部・下垂体後葉機能の検討

夏目修, 穴井洋, 田岡俊昭

日本泌尿器科学会雑誌 Vol. 94 ( 2 ) page： 136 2003

Vasogenic edema and VEGF expression in a rat two-vein occlusion model

Kimura R., Nakase H., Sakaki T., Taoka T., Tsuji T.

Acta Neurochirurgica, Supplementum ( 86 ) page： 213 - 217 2003

Language：English Publishing type：Research paper (scientific journal) Publisher：Acta Neurochirurgica, Supplementum

Vasogenic edema plays an important etiologic role in the pathogenesis of cerebral venous circulation disturbances (CVCDs). Since vascular endothelial growth factor (VEGF) is a major mediator in angiogenesis and vascular permeability, including induction of vasogenic edema, the present study was undertaken to investigate whether it has any relevance to CVCDs. Male Wistar rats (n = 15) were used. Two adjacent cortical veins were occluded photochemically using rose bengal dye and fiberoptic illumination, with evaluation 24 hours thereafter by magnetic resonance imaging (MRI). Each brain was removed from the skull immediately after MRI and processed for hematoxylin-eosin staining (H&E staining) of sections for histopathology and comparison with MRI data. VEGF expression as demonstrated immunohistochemically appeared to coincide with vasogenic edema, diagnosed as high intensity areas on apparent diffusion coefficient of water (ADCw) maps. On the basis of these data, we conclude that VEGF is related to formation of vasogenic edema in the acute stage of CVCD. © Springer-Verlag 2003.

DOI： 10.1007/978-3-7091-0651-8_46