Faculty Profiles - TAOKA Toshiaki

Impact of the Glymphatic System on the Kinetic and Distribution of Gadodiamide in the Rat Brain: Observations by Dynamic MRI and Effect of Circadian Rhythm on Tissue Gadolinium Concentrations. Reviewed International coauthorship International journal

Toshiaki Taoka, Gregor Jost, Thomas Frenzel, Shinji Naganawa, Hubertus Pietsch

Investigative radiology Vol. 53 ( 9 ) page： 529 - 534 2018.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Ovid Technologies (Wolters Kluwer Health)

OBJECTIVES: The glymphatic system is a recently hypothesized waste clearance system of the brain in which perivascular space constitutes a pathway similar to the lymphatic system in other body regions. Sleep and anesthesia are reported to influence the activity of the glymphatic system. Because rats are nocturnal animals, the glymphatic system is expected to be more active during the day. We attempted to elucidate the influence of the glymphatic system for intravenously injected gadodiamide in the rat brain by 2 experiments. One was a magnetic resonance imaging (MRI) experiment to evaluate the short-term dynamics of signal intensity changes after gadodiamide administration. The other was a quantification experiment to evaluate the concentration of retained gadolinium within the rat brain after repeated intravenous administration of gadodiamide at different times of day and levels of anesthesia. MATERIALS AND METHODS: The imaging experiment was performed on 6 rats that received an intravenous injection of gadodiamide (1 mmol/kg) and dynamic MRI for 3 hours at 2.4-minute intervals. The time course of the signal intensity changes was evaluated for different brain structures. The tissue quantification experiment was performed on 24 rats divided into 4 groups by injection time (morning, late afternoon) and anesthesia (none, short, long) during administration. All animals received gadodiamide (1.8 mmol/kg, 8 times over 2 weeks). Gadolinium concentration of dissected brain tissues was quantified 5 weeks after the last administration by inductively coupled plasma mass spectrometry. RESULTS: In the imaging experiment, muscle and the fourth ventricle showed an instantaneous signal intensity increase immediately after gadodiamide injection. The signal curve of the cerebral cortex and deep cerebellar nuclei reached the peak signal intensity later than the fourth ventricle but earlier than that of the prepontine cistern. In the gadolinium quantification experiment, the concentration in the group with the morning injection showed a significantly lower concentration than the late afternoon injection group. The lowest tissue gadolinium concentrations were found in the groups injected in the morning during long anesthesia. CONCLUSIONS: Instantaneous transition of gadodiamide from blood to cerebrospinal fluid was indicated by dynamic MRI. The gadodiamide distribution to the cerebral cortex and deep cerebellar nuclei seemed to depend on both blood flow and cerebrospinal fluid. This confirms previous studies indicating that the cerebrospinal fluid is one potential pathway of gadolinium-based contrast agent entry into the brain. For the distribution and clearance of the gadodiamide from brain tissue, involvement of the glymphatic system seemed to be indicated in terms of the influence of sleep and anesthesia.

DOI： 10.1097/RLI.0000000000000473

Prediction of Intracranial Arterial Stenosis Progression in Patients with Moyamoya Vasculopathy: Contrast-Enhanced High-Resolution Magnetic Resonance Vessel Wall Imaging. Reviewed International journal

Shinsuke Muraoka, Yoshio Araki, Toshiaki Taoka, Hisashi Kawai, Sho Okamoto, Kenji Uda, Shinji Ota, Shinji Naganawa, Toshihiko Wakabayashi

World neurosurgery Vol. 116 page： E1114 - E1121 2018.8

Language：English Publishing type：Research paper (scientific journal)

OBJECTIVE: Moyamoya vasculopathy (MMV) is characterized by progressive stenosis of the intracranial arteries. MMV currently has no curative treatments, and cerebral ischemia and hemorrhage are the major outcomes. Evaluation of the stroke risk of each patient resulting from the progression of intracranial arterial stenosis is clinically important. METHODS: We prospectively reviewed patients with intracranial arterial stenosis and already diagnosed MMV. High-resolution magnetic resonance imaging using contrast agent is the novel vessel wall imaging (VWI) technique for directly evaluating vascular walls and intracranial artery disease. All patients underwent high-resolution vessel wall imaging and magnetic resonance angiography at the time of registration, and they underwent follow-up magnetic resonance angiography. The Fisher exact test was used to assess associations between the degrees of wall enhancement and between stable and progressive intracranial arterial stenosis. RESULTS: A total of 24 patients (17 female; mean age, 36.1 ± 16.8 years; range 3-67 years) with MMV were consecutively recruited to this study. Progression of stenosis was shown in 6 lesions (66.6%) on strong enhancement, 2 lesions (12.5%) on mild enhancement, and 1 lesion (4.3%) on lack of enhancement. Arterial vessel wall enhancement in MMV patients correlated closely with progression of intracranial arterial stenosis (P = 0.002). CONCLUSIONS: Arterial vessel wall enhancement in MMV patients was closely related to progression of intracranial arterial stenosis. Strong enhancement of the intracranial vessel wall was associated with intracranial arterial stenosis progression, and lack of enhancement correlated with the stability of intracranial arterial stenosis.

DOI： 10.1016/j.wneu.2018.05.181

Imaging Differences between Neuromyelitis Optica Spectrum Disorders and Multiple Sclerosis: A Multi-Institutional Study in Japan Reviewed

A guide to identification and selection of axial planes in magnetic resonance imaging of the brain. Reviewed International coauthorship International journal

Otake S, Taoka T, Maeda M, Yuh WT

The neuroradiology journal Vol. 31 ( 4 ) page： 336 - 344 2018.8

Language：English Publishing type：Research paper (scientific journal) Publisher：{SAGE} Publications

For brain magnetic resonance (MR) examination, three-dimensional imaging is commonly performed. Radiologists need to know the appropriate imaging angle for viewing. We present six imaging angles for the axial images. Each angle is determined by the reference line. The landmarks on the midsagittal MR image to determine the angle of the reference lines are as follows: the supraorbito-meatal line (the center of the mammillary body and the fastigium of the fourth ventricle), the orbito-meatal (OM) line (the center of the mammillary body and the most posterior point of the cerebellar tentorium), the Talairach anterior commissure (AC)-posterior commissure (PC) line (the superior edge of the AC and the inferior edge of the PC), the Schaltenbrand AC-PC line (the center of the AC and the center of the PC), the subcallosal line (the inferior border of the genu and the inferior border of the splenium of the corpus callosum), Reid's baseline (the center of the pituitary gland and the most posterior point of the cerebellar tentorium) and the brainstem vertical line (the line perpendicular to the posterior border of the brainstem). The AC-PC line is most commonly used in MR examination. The OM line is most commonly used in computed tomography examination. The supraorbito-meatal line is recommended for avoiding irradiation to the orbit. In cases of multiple sclerosis, the subcallosal line is recommended in the guidelines. For lesions in the orbital cavity, paranasal cavity or skull base, Reid's baseline is useful. For cases of brainstem lesions, the brainstem vertical line is useful.

DOI： 10.1177/1971400918769911

H. Tatekawa, S. Sakamoto, M. Hori, Y. Kaichi, A. Kunimatsu, K. Akazawa, T. Miyasaka, H. Oba, T. Okubo, K. Hasuo, K. Yamada, T. Taoka, S. Doishita, T. Shimono, Y. Miki

American Journal of Neuroradiology Vol. 39 ( 7 ) page： 1239 - 1247 2018.7

特集知っておきたいMRI画像診断のコツ中枢神経　頭部外傷

宮坂俊輝, 田岡俊昭

臨床画像 Vol. 34 ( 13 ) page： 63 - 71 2018.4

Computer-assisted cognitive remediation therapy increases hippocampal volume in patients with schizophrenia: A randomized controlled trial Reviewed International journal

Tsubasa Morimoto, Yasuhiro Matsuda, Kiwamu Matsuoka, Fumihiko Yasuno, Emi Ikebuchi, Hiroyuki Kameda, Toshiaki Taoka, Toshiteru Miyasaka, Kimihiko Kichikawa, Toshifumi Kishimoto

BMC Psychiatry Vol. 18 ( 1 ) page： 83 - 83 2018.3

Language：English Publishing type：Research paper (scientific journal) Publisher：BioMed Central Ltd.

Background: Cognitive remediation therapy (CRT) effectively reduces neurocognitive impairment in patients with schizophrenia, but few studies have used structural neuroimaging methods to assess its neuroanatomical effects. We investigated these effects, as well as the association between changes in cortical volume and neurocognitive performance. Method: Between August 2013 and September 2016, we performed a randomized controlled study comprising a CRT group (16 individuals) and a treatment-as-usual (TAU) group (15 individuals) of patients with schizophrenia. CRT participants engaged in twice-weekly computer-assisted CRT sessions and weekly group meetings for 12 weeks. T1-weighted magnetic resonance imaging was performed before and after the intervention period, and whole-brain voxel-based morphometric analysis was used to detect significant cortical gray matter volume changes. We also assessed the correlation between cortical volume changes and CRT-derived neurocognitive improvements. Results: The CRT group exhibited significantly greater improvements than the TAU group in verbal fluency (P = 0.012) and global cognitive scores (P = 0.049). The CRT group also exhibited significantly greater increases in right hippocampal volume than the TAU group (P &lt
0.001). Changes in verbal fluency scores and right hippocampal volumes were positively correlated (r = 0.53, P = 0.001). Conclusion: We found that CRT significantly increased right hippocampal volumes and that these enhancements were positively correlated with changes in verbal fluency scores. Our results indicate that CRT induces cognitive improvement through hippocampal plasticity.

DOI： 10.1186/s12888-018-1667-1

特集脳脊髄液動態のすべて脳脊髄液による老廃物のクリアランス−glymphaticシステム−

頭部の鑑別診断のポイント第7章血管の異常　2. 血管壁の異常を示す疾患の鑑別

田岡俊昭

画像診断 Vol. 38 ( 4 ) page： s152 - s159 2018.3

田岡俊昭, 長縄慎二

画像診断 Vol. 38 ( 3 ) page： 268 - 276 2018.2

Appearance of the Organum Vasculosum of the Lamina Terminalis on Contrast-enhanced MR Imaging. Reviewed

Shinji Naganawa, Toshiaki Taoka, Hisashi Kawai, Masahiro Yamazaki, Kojiro Suzuki

Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine Vol. 17 ( 2 ) page： 132 - 137 2018

Language：English Publishing type：Research paper (scientific journal) Publisher：Japanese Society for Magnetic Resonance in Medicine

PURPOSE: Circumventricular organs (CVOs) lack a blood brain barrier and are also called "brain windows". Among CVOs, the organum vasculosum of the lamina terminalis (OVLT) is an osmotic regulator involved in the release of vasopressin. In a previous study of healthy subjects, it was reported that contrast enhancement in the OVLT can be recognized in only 34% of 3 Tesla thin slice contrast-enhanced T1-weighted images. The purpose of this study was to evaluate the leakage of gadolinium contrast from the OVLT in healthy subjects using heavily T2-weighted three dimensional-fluid attenuated inversion recovery (3D-FLAIR) (HF) imaging. METHODS: Eight healthy male subjects were included in this study. A standard dose (0.1 mmol/kg) of gadoteridol was intravenously administered. Magnetic resonance cisternography (MRC) and HF were obtained before and 0.5, 1.5, 3, 4.5 and 6 h after the injection. Enhancement of the OVLT including the surrounding cerebral spinal fluid (CSF) was measured by manually drawing a rectangular ROI centered on the OVLT. The ROI was copied to the HF image and the signal intensity was measured. The signal intensity ratio (SIR) was obtained by dividing the signal intensity value of the OVLT ROI by that of the midbrain. RESULTS: The differences between the mean SIR at pre-contrast and those at 0.5, 1.5, 3, 4.5, and 6 h were significant (P < 0.05). The mean SIR at 0.5 h was higher than those at all other time points (P < 0.05). CONCLUSION: Using HF imaging, enhancement around the OVLT was observed in all subjects at 0.5 h after intravenous administration of single dose gadoteridol.

DOI： 10.2463/mrms.mp.2017-0088

Differences in Signal Intensity and Enhancement on MR Images of the Perivascular Spaces in the Basal Ganglia versus Those in White Matter. Reviewed

Shinji Naganawa, Toshiki Nakane, Hisashi Kawai, Toshiaki Taoka

Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine Vol. 17 ( 4 ) page： 301 - 307 2018

Language：English Publishing type：Research paper (scientific journal) Publisher：Japanese Society for Magnetic Resonance in Medicine

PURPOSE: To elucidate differences between the perivascular space (PVS) in the basal ganglia (BG) versus that found in white matter (WM) using heavily T2-weighted FLAIR (hT2-FL) in terms of 1) signal intensity on non-contrast enhanced images, and 2) the degree of contrast enhancement by intravenous single dose administration of gadolinium based contrast agent (IV-SD-GBCA). MATERIALS AND METHODS: Eight healthy men and 13 patients with suspected endolymphatic hydrops were included. No subjects had renal insufficiency. All subjects received IV-SD-GBCA. MR cisternography (MRC) and hT2-FL images were obtained prior to and 4 h after IV-SD-GBCA. The signal intensity of the PVS in the BG, subinsular WM, and the cerebrospinal fluid (CSF) in Ambient cistern (CSFAC) and CSF in Sylvian fissure (CSFSyl) was measured as well as that of the thalamus. The signal intensity ratio (SIR) was calculated by dividing the intensity by that of the thalamus. We used 5% as a threshold to determine the significance of the statistical test. RESULTS: In the pre-contrast scan, the SIR of the PVS in WM (Mean ± standard deviation, 1.83 ± 0.46) was significantly higher than that of the PVS in the BG (1.05 ± 0.154), CSFSyl (1.03 ± 0.15) and the CSFAC (0.97 ± 0.29). There was no significant difference between the SIR of the PVS in the BG compared to the CSFAC and CSFSyl. For the evaluation of the contrast enhancement effect, significant enhancement was observed in the PVS in the BG, the CSFAC and the CSFSyl compared to the pre-contrast scan. No significant contrast enhancement was observed in the PVS in WM. CONCLUSION: The signal intensity difference between the PVS in the BG versus WM on pre-contrast images suggests that the fluid composition might be different between these PVSs. The difference in the contrast enhancement between the PVSs in the BG versus WM suggests a difference in drainage function.

DOI： 10.2463/mrms.mp.2017-0137

Gadolinium-based Contrast Media, Cerebrospinal Fluid and the Glymphatic System: Possible Mechanisms for the Deposition of Gadolinium in the Brain. Reviewed

Toshiaki Taoka, Shinji Naganawa

Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine Vol. 17 ( 2 ) page： 111 - 119 2018

Language：English Publishing type：Research paper (scientific journal) Publisher：Japanese Society for Magnetic Resonance in Medicine

After Kanda's first report in 2014 on gadolinium (Gd) deposition in brain tissue, a considerable number of studies have investigated the explanation for the observation. Gd deposition in brain tissue after repeated administration of gadolinium-based contrast medium (GBCM) has been histologically proven, and chelate stability has been shown to affect the deposition. However, the mechanism for this deposition has not been fully elucidated. Recently, a hypothesis was introduced that involves the 'glymphatic system', which is a coined word that combines 'gl' for glia cell and 'lymphatic' system. According to this hypothesis, the perivascular space functions as a conduit for cerebrospinal fluid to flow into the brain parenchyma. The perivascular space around the arteries allows cerebrospinal fluid to enter the interstitial space of the brain tissue through water channels controlled by aquaporin 4. The cerebrospinal fluid entering the interstitial space clears waste proteins from the tissue. It then flows into the perivascular space around the vein and is discharged outside the brain. In addition to the hypothesis regarding the glymphatic system, some reports have described that after GBCM administration, some of the GBCM distributes through systemic blood circulation and remains in other compartments including the cerebrospinal fluid. It is thought that the GBCM distributed into the cerebrospinal fluid cavity via the glymphatic system may remain in brain tissue for a longer duration compared to the GBCM in systemic circulation. Glymphatic system may of course act as a clearance system for GBCM from brain tissue. Based on these findings, the mechanism for Gd deposition in the brain will be discussed in this review. The authors speculate that the glymphatic system may be the major contributory factor to the deposition and clearance of gadolinium in brain tissue.

DOI： 10.2463/mrms.rev.2017-0116

Single-stage Coil Embolization for Kissing Aneurysms of the Internal Carotid Artery Using Enterprise Stent: Three Cases Reports Reviewed

Takeshi Wada, Katsutoshi Takayama, Toshiaki Taoka, Kaoru Myouchin, Hiroyuki Nakagawa, Ichiro Nakagawa, Toshiteru Miyasaka, Shinichiro Kurokawa, Kimihiko Kichikawa

Journal of Neuroendovascular Therapy Vol. 12 ( 1 ) page： 6 - 13 2018

Language：English Publishing type：Research paper (scientific journal) Publisher：The Japanese Society for Neuroendovascular Therapy

Purpose: Kissing aneurysms (KAs) are caused by the rare incidence of two aneurysms with different cervixes mutually contacting each other, with craniotomy surgical clipping having been reported as difficult. The objective was to investigate the treatment outcome of single-stage coil embolization using an Enterprise stent for internal carotid artery KA.Materials and Methods: The subjects consisted of three cases and six aneurysms (women: two cases, age: 42–70 years old, average: 55.7 years old) that underwent single-stage coil embolization using an Enterprise stent. Localization of the aneurysms was as follows: internal carotid artery-ophthalmic arterial bifurcation and internal carotid artery (C3): one case; internal carotid artery-posterior communicating arterial bifurcation and anterior choroidal arterial bifurcation: two cases; wherein, the maximum aneurysm diameter was 2.8–7.6 mm (average: 5.1 mm). The technical success rate, the presence of perioperative complications, the degree of embolus follow-up cerebral angiography after treatment (4–6 months, average: after 4.7 months), and more than 3 years follow-up contrast-enhanced magnetic resonance angiography (after 3.4–4.1 years, average: after 3.7 years) were assessed.Results: Coil embolization was successful in all cases, with no observation of perioperative complications. Upon follow-up angiography, complete occlusion (CO) was observed in all three cases and six aneurysms.Conclusion: The initial treatment outcome of single-stage coil embolization for carotid KA using an Enterprise stent was good.

DOI： 10.5797/jnet.oa.2017-0017

CiNii Research

特集中枢神経系の新たな疾患カテゴリーとその画像所見 Glymphaticシステム　脳内の老廃物排除のための仕組み

田岡俊昭, 長縄慎二

臨床画像 Vol. 33 ( 12 ) page： 1447 - 1458 2017.12

Diffusion tensor tractography in the preoperative precise identification of the course of facial nerve in a meningioma of the cerebellopontine angle – Technical implications Reviewed International coauthorship

Gonçalo Neto d'Almeida, Luís Sousa Marques, Pedro Escada, Toshiaki Taoka, Pedro Gonçalves Pereira

Interdisciplinary Neurosurgery: Advanced Techniques and Case Management Vol. 9 page： 58 - 60 2017.9

Language：English Publishing type：Research paper (scientific journal) Publisher：Elsevier B.V.

Background Facial paralysis remains as one of the major morbidities of surgery of cerebellopontine angle tumors. The preoperative standard Magnetic Resonance Image does not identify, with precision, the path of the facial nerve. Case description The authors describe a case of a 56 years-old female with a cerebellopontine angle meningioma, submitted to preoperative Diffusion Tensor Tractography to identification of the course of the facial nerve, and correlate its position with the intraoperative findings. There was an accurate correlation between the path of the facial nerve revealed by preoperative DTT and the route of the nerve identified during surgery. Conclusion The preoperative identification of the facial nerve seems to be possible by tractography in meningiomas of the cerebellopontine angle. It is possible that this technique may have utility in larger tumors, where the intraoperative identification of the facial path can be more difficult.

DOI： 10.1016/j.inat.2017.03.010