Faculty Profiles - TAOKA Toshiaki

Papers - TAOKA Toshiaki

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Efficacy and safety of non-suture dural closure using a novel dural substitute consisting of polyglycolic acid felt and fibrin glue to prevent cerebrospinal fluid leakage-A non-controlled, open-label, multicenterclinical trial- Reviewed International journal

Shunsuke Terasaka, Toshiaki Taoka, Satoshi Kuroda, Nobutaka Mikuni, Toru Nishi, Hiroyuki Nakase, Yukihiko Fujii, Yasuhiko Hayashi, Jun-ichi Murata, Ken-ichiro Kikuta, Toshihiko Kuroiwa, Sachie Shimokawa, Kiyohiro Houkin

JOURNAL OF MATERIALS SCIENCE-MATERIALS IN MEDICINE Vol. 28 ( 5 ) page： 69 - 69 2017.5

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

The objective of this study is to evaluate the efficacy and safety of non-suture dural closure using a novel dural substitute (GM111) consisting of polyglycolic acid felt with a fibrin-glue-coated area commensurate in size with the dural defect. This was a non-controlled, open-label, multicenter clinical trial. The efficacy evaluation endpoints were (1) GM111's intra-operative capability to close dural defects and (2) prevention of cerebrospinal fluid (CSF) leakage and subcutaneous CSF retention throughout the postoperative period (evaluated by diagnostic imaging). Patients meeting the following three preoperative and two intra-operative selection criteria were enrolled: (1) between 12 and <75 years of age; (2) the dura is surmised to be defective and in need of reconstruction; (3) informed written consent was obtained from the patient; (4) the surgical wound is class 1; and (5) the size of duraplasty is >= 0.2 cm(2) to <100 cm(2). Sixty patients were enrolled. The craniotomy site was supratentorial in 77.2%, infratentorial in 12.3% and sellar in 10.5%. The GM111 prosthesis size ranged from 0.24 to 42 cm(2). To evaluate the efficacy, intra-operative closure was confirmed by Valsalva's maneuver, water infusion, etc., in all patients. CSF leakage and subcutaneous CSF retention throughout the postoperative period were found in four patients. Adverse events for which a causal relationship with GM111 could not be ruled out occurred in 8.8% of the patients. There were no instances of postoperative infection due to GM111. GM111 showed good closure capability and safety when used for non-suture dural closure.

DOI： 10.1007/s10856-017-5877-8

Carotid Artery Stenting Investigation of Plaque Protrusion Incidence and Prognosis Reviewed International journal

Masashi Kotsugi, Katsutoshi Takayama, Kaoru Myouchin, Takeshi Wada, Ichiro Nakagawa, Hiroyuki Nakagawa, Toshiaki Taoka, Shinichiro Kurokawa, Hiroyuki Nakase, Kimihiko Kichikawa

JACC-CARDIOVASCULAR INTERVENTIONS Vol. 10 ( 8 ) page： 824 - 831 2017.4

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

OBJECTIVES This study sought to clarify the incidence and prognosis of PP in carotid artery stenting (CAS).
BACKGROUND Projections thought to be plaque may be observed inside the stent on angiography or intravascular ultrasound (IVUS) during CAS. Known as plaque protrusion (PP), the incidence and prognosis of this complication are unclear.
METHODS A total of 354 consecutive carotid atherosclerotic stenoses in 328 patients (285 men, 43 women; age range 51 to 97 years [mean age 73.6 years]; 158 symptomatic cases; stenosis rate, 50% to 99% [mean 81.0%]) who underwent CAS under IVUS between October 2007 and March 2016 were retrospectively analyzed. PP was defined as plaque seen inside the stent lumen on both digital subtraction angiography and IVUS. The incidence and prognosis (rate of stroke within 30 post-operative days) of PP and the rate of ischemic lesions on the treated side on diffusion-weighted imaging performed within 48 post-operative hours within the PP group were investigated.
RESULTS PP was observed in 9 cases (2.6%). Ischemic stroke occurred in 6 of 9 PP cases (66.7%; 1 major, 5 minor). Ischemic lesions were observed on diffusion-weighted imaging in 8 of 9 cases (88.9%). PP was strongly associated with perioperative ischemic stroke. A significant increase in PP susceptibility was observed with open-cell stent use and unstable plaque.
CONCLUSIONS The incidence of PP in CAS was 2.6%, with a high risk of ischemic complications if PP was observed. The present findings indicate the necessity of appropriate device selection to avoid PP. (C) 2017 by the American College of Cardiology Foundation.

DOI： 10.1016/j.jcin.2017.01.029

すとらびすむす青い瞬間,魔法の時間

田岡俊昭

画像診断 Vol. 37 ( 3 ) page： 247 - 247 2017.2

Structure of the Medullary Veins of the Cerebral Hemisphere and Related Disorders Reviewed International journal

Toshiaki Taoka, Akio Fukusumi, Toshiteru Miyasaka, Hisashi Kawai, Toshiki Nakane, Kimihiko Kichikawa, Shinji Naganawa

RADIOGRAPHICS Vol. 37 ( 1 ) page： 280 - 296 2017.1

Language：English Publishing type：Research paper (scientific journal) Publisher：RADIOLOGICAL SOC NORTH AMERICA

Deep medullary veins drain into subependymal veins with four convergence zones and show parallel distribution patterns adjacent to the body or inferior horn and a radial pattern in the frontal horn or trigon of the lateral ventricle. As white matter imaging develops such as diffusion tensor imaging or susceptibility-weighted imaging, requirements for understanding of white matter structures are increasing, not only for understanding of neuronal tracts but also for that of other structures including the fine anatomy of white matter vessels. Some disorders are related to deep medullary veins and show characteristic distributions of the lesions indicating the relationship to the medullary veins. When lesions show a parallel or radial distribution pattern in the certebral deep white matter, disorders related to deep medullary veins should be considered for differential diagnosis. In this review, we discuss disorders related to deep medullary veins, including (a) anomalies of the medullary veins, (b) hemorrhagic disorders related to the medullary veins (diffuse vascular injury due to high-energy trauma, deep medullary vein engorgement/thrombosis in neonates), (c) inflammatory changes that spread along the medullary veins, (d) neoplasms within the medullary veins, and (e) metabolic changes that lead to altered visualization of medullary veins. Understanding the anatomic structure of medullary veins in the cerebral hemisphere and becoming familiar with disorders in which the medullary veins play a major role in disease development may be helpful in the interpretation of brain images. (C) RSNA, 2017

DOI： 10.1148/rg.2017160061

Revisiting Current Golden Rules in Managing Acute Ischemic Stroke: Evaluation of New Strategies to Further Improve Treatment Selection and Outcome Reviewed

William T. C. Yuh, Matthew David Alexander, Toshihiro Ueda, Masayuki Maeda, Toshiaki Taoka, Kei Yamada, Norman J. Beauchamp

AMERICAN JOURNAL OF ROENTGENOLOGY Vol. 208 ( 1 ) page： 32 - 41 2017.1

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

OBJECTIVE. Advanced stroke imaging has generated much excitement for the early diagnosis of acute ischemic stroke (AIS) and facilitation of intervention. However, its therapeutic impact has not matched its diagnostic utility; most notably, lacking significant contributions to recent major AIS clinical trials. It is time to reexamine the fundamental hypotheses from the enormous body of imaging research on which clinical practices are based and reassess the current standard clinical and imaging strategies, or golden rules, established over decades for AIS. In this article, we will investigate a possible new window of opportunity in managing AIS through a better understanding of the following: first, the potential limitations of the golden rules; second, the significance of imaging-based parenchymal hypoperfusion (i.e., lower-thannormal relative cerebral blood flow [rCBF] may not be indicative of ischemia); third, the other critical factors (e.g., rCBF, collateral circulation, variable therapeutic window, chronicity of occlusion) that reflect more individual ischemic injury for optimal treatment selection; and, fourth, the need for penumbra validation in successfully reperfused patients (not in untreated patients).
CONCLUSION. Individual variations in the therapeutic window, ischemic injury (rCBF), and chronicity of vascular lesion development have not been comprehensively incorporated in the standard algorithms used to manage AIS. The current established imaging parameters have not been consistently validated with successfully reperfused patients and rCBF to quantitatively distinguish between oligemia and ischemia and between penumbra and infarct core within ischemic tissue. A novel paradigm incorporating rCBF values or indirectly incorporating relative rCBF values with higher statistically powered imaging studies to more reliably assess the severity of ischemic injury and differentiate reversibility from viability within the area of imaging-based parenchymal hypoperfusion may provide a more personalized approach to treatment, including no treatment of infarction core, to further enhance outcomes.

DOI： 10.2214/AJR.16.16557

Visualization of Middle Ear Ossicles in Elder Subjects with Ultra-short Echo Time MR Imaging Reviewed

Shinji Naganawa, Toshiki Nakane, Hisashi Kawai, Toshiaki Taoka, Kojiro Suzuki, Shingo Iwano, Hiroko Satake, David Grodzki

MAGNETIC RESONANCE IN MEDICAL SCIENCES Vol. 16 ( 2 ) page： 93 - 97 2017

Language：English Publishing type：Research paper (scientific journal) Publisher：JPN SOC MAGNETIC RESONANCE MEDICINE

Purpose: To evaluate the visualization of middle ear ossicles by ultra-short echo time magnetic resonance (MR) imaging at 3T in subjects over 50 years old.
Materials and Methods: Sixty ears from 30 elder patients that underwent surgical or interventional treatment for neurovascular diseases were included (ages: 50-82, median age: 65; 10 men, 20 women). Patients received follow-up MR imaging including routine T1-and T2-weighted images, time-of-flight MR angiography, and ultra-short echo time imaging (PETRA, pointwise encoding time reduction with radial acquisition). All patients underwent computed tomography (CT) angiography before treatment. Thin-section source CT images were correlated with PETRA images. Scan parameters for PETRA were: TR 3.13, TE 0.07, flip angle 6 degrees, 0.83 x 0.83 x 0.83 mm resolution, 3 min 43 s scan time. Two radiologists retrospectively evaluated the visibility of each ossicular structure as positive or negative using PETRA images. The structures evaluated included the head of the malleus, manubrium of the malleus, body of the incus, long process of the incus, and the stapes. Signal intensity of the ossicles was classified as: between labyrinthine fluid and air, similar to labyrinthine fluid, between labyrinthine fluid and cerebellar parenchyma, or higher than cerebellar parenchyma.
Results: In all ears, the body of the incus was visible. The head of the malleus was visualized in 36/60 ears. The manubrium of the malleus and long process of the incus was visualized in 1/60 and 4/60 ears, respectively. The stapes were not visualized in any ear. Signal intensity of the visible structures was between labyrinthine fluid and air in all ears.
Conclusion: The body of the incus was consistently visualized with intensity between air and labyrinthine fluid on PETRA images in aged subjects. Poor visualization of the manubrium of the malleus, long process of the incus, and the stapes limits clinical significance of middle ear imaging with current PETRA methods.

DOI： 10.2463/mrms.mp.2015-0171

Gd-based Contrast Enhancement of the Perivascular Spaces in the Basal Ganglia Reviewed

Shinji Naganawa, Toshiki Nakane, Hisashi Kawai, Toshiaki Taoka

MAGNETIC RESONANCE IN MEDICAL SCIENCES Vol. 16 ( 1 ) page： 61 - 65 2017

Language：English Publishing type：Research paper (scientific journal) Publisher：JPN SOC MAGNETIC RESONANCE IN MEDICINE

Purpose: In textbooks, the perivascular space (PVS) is described as non-enhancing after the intravenous administration of gadolinium-based contrast agent (IV-GBCA). We noticed that the PVS sometimes has high signal intensity (SI) on heavily T-2-weighted 3D-FLAIR (hT(2)-FL) images obtained 4 h after IV-GBCA. The purpose of this study was to retrospectively evaluate the contrast enhancement of the PVS.
Materials and Methods: In 8 healthy subjects and 19 patients with suspected endolymphatic hydrops, magnetic resonance cisternography (MRC) and hT(2)-FL images were obtained before and 4 h after a single dose of IV-GBCA. No subjects had renal insufficiency. On axial MRC at the level of the anterior commissure (AC)-posterior commissure (PC) line, 1 cm circular regions of interest (ROIs) were drawn centering on the PVS in the bilateral basal ganglia and thalami. Three-millimeter diameter ROIs were set in the cerebrospinal fluid (CSF) of the bilateral ambient cistern. The ROIs on MRC were copied onto the hT2-FL images and the SI was measured. The SI ratio (SIR) was defined as SIRPVS = SI of PVS/SI of the thalami, and SIRCSF = SI of CSF/SI of the thalami. The average of the bilateral values was used for the calculation. The SIRCSF, SIRPVS, and SI of the thalami were compared between before and 4 h after IV-GBCA.
Results: The SIR was increased significantly from 1.02 +/- 0.37 to 2.65 +/- 0.82 in the CSF (P < 0.01) and from 1.20 +/- 0.35 to 2.13 +/- 1.23 in the PVS at 4 h after IV-GBCA (P < 0.01). The SI of the thalami showed no significant difference.
Conclusion: The enhancement of the PVS at 4 h after IV-GBCA was confirmed even in subjects without renal insufficiency. It is possible that the GBCA in the blood vessels might have permeated into the cerebrospinal fluid (CSF) space and the PVS. This might be a first step in the imaging evaluation of the glymphatic system (waste clearance system) of the brain.

DOI： 10.2463/mrms.mp.2016-0039

Lack of Contrast Enhancement in a Giant Perivascular Space of the Basal Ganglion on Delayed FLAIR Images: Implications for the Glymphatic System. 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. 16 ( 2 ) page： 89 - 90 2017

Improved HYDROPS: Imaging of Endolymphatic Hydrops after Intravenous Administration of Gadolinium. Reviewed

Shinji Naganawa, Hisashi Kawai, Toshiaki Taoka, Michihiko Sone

Magnetic resonance in medical sciences : MRMS : an official journal of Japan Society of Magnetic Resonance in Medicine Vol. 16 ( 4 ) page： 357 - 361 2017

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

To improve the imaging protocol for the evaluation of endolymphatic hydrops after intravenous administration of a gadolinium-based contrast agent, we modified our previously reported hybrid of reversed image of positive endolymph signal and native image of positive perilymph signal (HYDROPS) method. Although the scan time of the new protocol was half that of the previous one, there were no significant differences between two protocols in the mean contrast noise ratio between the endolymph and perilymph and the area ratio of the endolymph size values in nine patients.

DOI： 10.2463/mrms.tn.2016-0126

Structures Showing Negative Correlations of Signal Intensity with Postnatal Age on T-1-weighted Imaging of the Brain of Newborns and Infants Reviewed

Saeka Hori, Toshiaki Taoka, Tomoko Ochi, Toshiteru Miyasaka, Masahiko Sakamoto, Katsutoshi Takayama, Takeshi Wada, Kaoru Myochin, Yukihiro Takahashi, Kimihiko Kichikawa

MAGNETIC RESONANCE IN MEDICAL SCIENCES Vol. 16 ( 4 ) page： 333 - 339 2017

Language：English Publishing type：Research paper (scientific journal) Publisher：JPN SOC MAGNETIC RESONANCE MEDICINE

Purpose: Although the neonatal and infantile brain typically shows sequential T-1 shortening according to gestational age as a result of myelination, several structures do not follow this rule. We evaluated the relationship between the signal intensity of various structures in the neonatal and infantile brain on T-1-weighted imaging (T1WI) and either postnatal or gestational age.
Materials and Methods: We examined magnetic resonance images from 120 newborns and infants without any abnormalities in the central nervous system. Written informed consent was obtained from all parents and the institutional review board approved the study. Gestational age at examination ranged from 35 weeks, 3 days to 46 weeks, 6 days, and postnatal age ranged from 7 days to 127 days. Signal intensity on T1WI was evaluated on a scale from Grade 1 (indistinguishable from surrounding structures) to Grade 4 (higher than cortex and close to fat). We evaluated relationships between the T-1 signal grades of various structures in the neonatal brain and postnatal or gestational age using Spearman's correlation analysis.
Results: Significant positive correlations were identified between T-1 signal grade and gestational age in the pyramidal tract (P < 0.001). Conversely, significant negative correlations were evident between T-1 signal grade and postnatal age (P < 0.001), in structures including the stria medullaris thalami, fornix cerebellar vermis, dentate nucleus and anterior pituitary gland.
Conclusion: Significant negative correlations exist between signal intensity on T1WI and postnatal age in some structures of the neonatal and infantile brain. Some mechanisms other than myelination might play roles in the course of signal appearance.

DOI： 10.2463/mrms.mp.2015-0168

Diffusion Tensor Imaging in Dementia Reviewed

Taoka Toshiaki

Neuroimaging Diagnosis for Alzheimer's Disease and Other Dementias page： 117 - 128 2017

特集脳腫瘍WHO2016　−読影のための実践講座− 転移性脳腫瘍

田岡俊昭

画像診断 Vol. 36 ( 13 ) page： 1303 - 1313 2016.10

Application of histogram analysis for the evaluation of vascular permeability in glioma by the K2 parameter obtained with the dynamic susceptibility contrast method: Comparisons with Ktrans obtained with the dynamic contrast enhance method and cerebral blood volume Reviewed International journal

Toshiaki Taoka, Hisashi Kawai, Toshiki Nakane, Saeka Hori, Tomoko Ochi, Toshiteru Miyasaka, Masahiko Sakamoto, Kimihiko Kichikawa, Shinji Naganawa

MAGNETIC RESONANCE IMAGING Vol. 34 ( 7 ) page： 896 - 901 2016.9

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

Purpose: The "K2" value is a factor that represents the vascular permeability of tumors and can be calculated from datasets obtained with the dynamic susceptibility contrast (DSC) method. The purpose of the current study was to correlate K2 with Ktrans, which is a well-established permeability parameter obtained with the dynamic contrast enhance (DCE) method, and determine the usefulness of K2 for glioma grading with histogram analysis.
Methods: The subjects were 22 glioma patients (Grade II: 5, III: 6, IV: 11) who underwent DSC studies, including eight patients in which both DSC and DCE studies were performed on separate days within 10 days. We performed histogram analysis of regions of interest of the tumors and acquired 20th percentile values for leakage-corrected cerebral blood volume (rCBV(20%ile)), K2 (K2(20%ile)), and for patients who underwent a DCE study, Ktrans (Ktrans(20%ile)).We evaluated the correlation between K2(20%ile) and Ktrans(20%ile) and the statistical difference between rCBV(20%ile) and K2(20%ile).
Results: We found a statistically significant correlation between K2(20%ile) and Ktrans(20%ile) (r = 0.717, p < 0.05). rCBV(20%ile) showed a significant difference between Grades II and III and between Grades II and IV, whereas K2(20%ile) showed a statistically significant (p < 0.05) difference between Grades II and IV and between Grades III and IV.
Conclusions: The K2 value calculated from the DSC dataset, which can be obtained with a short acquisition time, showed a correlation with Ktrans obtained with the DCE method and may be useful for glioma grading when analyzed with histogram analysis. (C) 2016 Elsevier Inc. All rights reserved.

DOI： 10.1016/j.mri.2016.04.020

Advantages of Diffusion Tensor Tractography of Facial Nerve in Vestibular Schwannomas Surgeries: A Multicenter Study Reviewed International coauthorship

Gon{\c{c } }alo Almeida, Pedro Pereira, Luis Marques, Pedro Escada, Kimihiko Kichikawa, Shinji Naganawa, Toshiaki Taoka

Journal of Neurological Surgery Part B: Skull Base Vol. 77 ( S 02 ) 2016.9

Diffusion tensor studies and voxel-based morphometry of the temporal lobe to determine the cognitive prognosis in cases of Alzheimer's disease and mild cognitive impairment: Do white matter changes precede gray matter changes? Reviewed International journal

Toshiaki Taoka, Fumihiko Yasuno, Masayuki Morikawa, Makoto Inoue, Kuniaki Kiuchi, Soichiro Kitamura, Kiwamu Matsuoka, Toshifumi Kishimoto, Kimihiko Kichikawa, Shinji Naganawa

SPRINGERPLUS Vol. 5 ( 1 ) page： 1023 - 1023 2016.7

Language：English Publishing type：Research paper (scientific journal) Publisher：SPRINGER INTERNATIONAL PUBLISHING AG

Purpose: The purpose of the current study was to assess the feasibility of diffusion tensor imaging (DTI) parameters for determining the prognosis of Alzheimer's disease (AD). We also analyzed the correlation among DTI, voxel-based morphometry (VBM), and results of the mini-mental state examination (MMSE).
Methods: The subjects of this prospective study were patients with AD and mild cognitive impairment. We performed annual follow-ups with DTI, VBM, and MMSE for 2 or 3 years. On DTI, the apparent diffusion coefficient (ADC) and fractional anisotropy (FA) of the uncinate fascicles were measured. VBM was performed to provide a z-score for the parahippocampal gyrus. The correlations among these factors were evaluated in the same period and the next period of the follow-up study.
Results: For evaluation of the same period, both DTI parameters and z-scores showed statistically significant correlations with the MMSE score. Also for evaluation of the next period, both DTI parameters and z-scores showed statistically significant correlations with the MMSE score of the next period. We observed a statistically significant correlation between the ADC value of the uncinate fascicles and the z-score of the next period.
Conclusions: Diffusion tensor parameters (ADC and FA) of the uncinate fascicles correlated well with cognitive function in the next year and seemed to be feasible for use as biomarkers for predicting the progression of AD. In addition, the white matter changes observed in the ADC seemed to precede changes in the gray matter volume of the parahippocampal gyrus that were represented by z-scores of VBM.

DOI： 10.1186/s40064-016-2692-5

Dural Thickening of the Internal Auditory Canal in Patients With Spontaneous Intracranial Hypotension Syndrome Reviewed International journal

Saeka Hori, Toshiaki Taoka, Toshiteru Miyasaka, Tomoko Ochi, Masahiko Sakamoto, Takeshi Wada, Kaoru Myochin, Katsutoshi Takayama, Kimihiko Kichikawa

JOURNAL OF COMPUTER ASSISTED TOMOGRAPHY Vol. 40 ( 2 ) page： 297 - 300 2016.3

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

Objective This study aimed to assess the utility of dural thickening of the internal auditory canal (IAC) in patients with spontaneous intracranial hypotension (SIH) syndrome and determined the sensitivity and specificity of this image finding.
Methods Magnetic resonance images were evaluated for 22 cases of definite SIH and 16 cases of unlikely SIH. On contrast-enhanced magnetic resonance imaging, pachymeningeal enhancement and dural thickening of the IAC were assessed.
Results Pachymeningeal enhancement was observed in 21 of 22 patients in the definite SIH group and 1 of 16 patients in the unlikely SIH group (sensitivity, 95.5%; specificity, 93.8%). Dural thickening of the IAC was observed in 15 of 22 patients in the definite SIH group and 0 of 16 patients in the unlikely SIH group (sensitivity, 68.2%; specificity, 100%).
Conclusions Dural thickening of the IAC showed 100% specificity for SIH syndrome and can increase the accuracy of diagnosis of SIH syndrome.

DOI： 10.1097/RCT.0000000000000342

Other Link： http://orcid.org/0000-0001-9227-0240

Time Course of Diffusion Kurtosis in Cerebral Infarctions of Transient Middle Cerebral Artery Occlusion Rat Model Reviewed International journal

Toshiaki Taoka, Masayuki Fujioka, Yuto Kashiwagi, Atsushi Obata, Takemi Rokugawa, Masaaki Hori, Yoshitaka Masutani, Shigeki Aoki, Shinji Naganawa, Kohji Abe

JOURNAL OF STROKE & CEREBROVASCULAR DISEASES Vol. 25 ( 3 ) page： 610 - 617 2016.3

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

Objective: To evaluate the relationship between fiber bundle direction and changes in diffusion kurtosis, we evaluated the apparent diffusion kurtosis coefficients (AKCs) that were perpendicular to and parallel to the principal diffusion tensor eigenvector. Materials and Methods: Adult male Wistar rats were subjected to 30 or 60 minutes of middle cerebral artery occlusion and imaged with a 7T Magnetic Resonance Imager System (Varian MRI System 7T/210: Agilent Technologies, CA). Diffusion kurtosis images were obtained before middle cerebral artery (MCA) reperfusion and 3, 6, and 24 hours after reperfusion to generate the apparent diffusion coefficient (ADC), fractional anisotropy (FA), mean apparent diffusion kurtosis coefficient (mAKC), AKC axial to the eigenvector (axAKC), and AKC radial to the eigenvector (radAKC) images. The time course of the region/normal ratio was evaluated for the above parameters in the caudoputamen and white matter. Results: Relative FA and relative ADC values decreased 3 hours after MCA reperfusion and remained decreased until 24 hours. Relative mAKC, axAKC, and radAKC values were increased 3 hours after MCA reperfusion, peaked after 6 hours, and slightly decreased after 24 hours. In the white matter, axAKC showed larger changes than radAKC. Conclusion: The time course of the diffusion kurtosis value showed earlier pseudonormalization than the ADC value of the lesions. For white matter lesions, the increase in axAKC was larger than that in radAKC, suggesting that the tissue changes after infarction mainly produce reduced diffusivity along the fibers and lead to increased inhomogeneity of the diffusion.

DOI： 10.1016/j.jstrokecerebrovasdis.2015.11.028

Other Link： http://orcid.org/0000-0001-9227-0240

Heavily T-2-Weighted 3D-FLAIR Improves the Detection of Cochlear Lymph Fluid Signal Abnormalities in Patients with Sudden Sensorineural Hearing Loss Reviewed

Shinji Naganawa, Hisashi Kawai, Toshiaki Taoka, Kojiro Suzuki, Shingo Iwano, Hiroko Satake, Michihiko Sone, Mitsuru Ikeda

MAGNETIC RESONANCE IN MEDICAL SCIENCES Vol. 15 ( 2 ) page： 203 - 211 2016

Language：English Publishing type：Research paper (scientific journal) Publisher：JPN SOC MAGNETIC RESONANCE IN MEDICINE

Purpose: To compare the signal increase in cochlear lymph fluid on three-dimensional fluid attenuated inversion recovery (3D-FLAIR) in patients with sudden sensorineural hearing loss (SNHL) between regular contrast 3D-FLAIR (FL) and heavily T-2-weighted 3D-FLAIR (HF).
Methods: Twenty-five patients with unilateral sudden SNHL and eight healthy volunteers were included. Patients were divided into two groups: the mild group consisted of 9 patients, with an average hearing level of 60 dB or less; the severe group consisted of 16 patients, with an average hearing level of more than 60 dB. All patients and healthy volunteers underwent magnetic resonance (MR) cisternography for anatomical reference of the fluid space with FL and HF at 3 T. The region of interest (ROI) was manually drawn on the mid-modiolar section of the MR cistemography around the cochlea. The ROI for noise was drawn within the air space. ROIs were copied onto the FL and HF images. The contrast-to-noise ratio (CNR) between the affected and non-affected ear was measured in the patient group and the CNR between the right and left ear was also measured in the control group. Differences in the CNR on FL and HF images among the three groups were tested by one-way analysis of variance (ANOVA).
Results: There was a statistically significant difference in mean CNR on HF among the three groups (P < 0.001). Furtheimore, based on pairwise comparisons, there was a statistically significant difference between them in mean CNR on HF (P < 0.05). There was no statistically significant difference in mean CNR on FL among the three groups (P = 0.074).
Conclusions: HF is more sensitive to signal alterations in cochleae with sudden SNHL than FL.

DOI： 10.2463/mrms.mp.2015-0065

Cochlear Lymph Fluid Signal Increase in Patients with Otosclerosis after Intravenous Administration of Gadodiamide Reviewed

Shinji Naganawa, Hisashi Kawai, Toshiaki Taoka, Kojiro Suzuki, Shingo Iwano, Hiroko Satake, Michihiko Sone, Mitsuru Ikeda

MAGNETIC RESONANCE IN MEDICAL SCIENCES Vol. 15 ( 3 ) page： 308 - 315 2016

Language：English Publishing type：Research paper (scientific journal) Publisher：JPN SOC MAGNETIC RESONANCE IN MEDICINE

Purpose: Increased cochlear lymph fluid signals on three-dimensional fluid-attenuated inversion recovery (3D-FLAIR) images obtained several minutes after intravenous administration of a single dose of gadolinium-based contrast agent (IV-SD-GBCA) in a patient with severe retro-fenestral type otosclerosis had been reported. This increase was thought to represent breakdown of the blood-labyrinthine barrier. The purpose of this study was to evaluate cochlear lymph signal on heavily T-2-weighted 3D-FLAIR (HF) images obtained 4 hours after IV-SD-GBCA in patients with otosclerosis, Meniere's disease, and healthy subjects.
Materials and Methods: Twenty-two ears from 12 patients with otosclerotic plaques determined by computed tomography (CT), 16 ears from 8 healthy volunteers, and 10 ears from 9 Meniere's disease patients with significant endolymphatic hydrops on magnetic resonance (MR) images were retrospectively analyzed. Images were obtained 4 hours after IV-SD-GBCA. Patients and healthy volunteers underwent MR cisternography (MRC) for anatomical reference of the fluid space and HF at 3T. The region of interest (ROI) was manually drawn on MRC images around the scala tympani in the basal cochlear turn. The reference ROI was set in the cerebellum. ROIs were copied onto HF images and the signal intensity ratio (SIR) of cochlear perilymph to cerebellum was measured. Differences in the SIR on HF images among the three groups were tested by one-way analysis of variance (ANOVA).
Results: The mean SIR was 24.0 +/- 10.1 in otosclerosis patients, 7.9 +/- 1.5 in volunteers, and 11.6 +/- 3.9 in Meniere's disease patients. The mean SIR was significantly higher in the otosclerosis group than in the other groups (P < 0.001). In the otosclerosis group, there was a significant difference in the SIR between the retrofenestral type and the fenestral type (P = 0.033).
Conclusions: In patients with otosclerosis, the SIR was higher than in Meniere's disease patients or in healthy volunteers. The SIR was higher in the retrofenestral type than in the fenestral type.

DOI： 10.2463/mrms.mp.2015-0121

Progress in magnetic resonance diffusion image Reviewed

Toshiaki Taoka

Japanese Journal of Neurosurgery Vol. 25 ( 5 ) page： 402 - 410 2016

Language：Japanese Publishing type：Research paper (scientific journal) Publisher：Japanese Congress of Neurological Surgeons

Diffusion of water is based on the principle that water molecules show random motion. In diffusion studies on magnetic resonance imaging using a motion proving gradient, a signal decrease which is caused by molecular diffusion in the tissue provides information about tissue structure and physiological status. Diffusion-weighted images play a very important role in brain related diagnosis, especially for acute infarctions, and have become an essential tool in clinical practice. Diffusion tensor imaging using the Gaussian distribution model also has made strides in evaluating anisotropic water diffusion in the white matter in which water diffusion is restricted by macromolecules, membrane, and myelin. Diffusion tensor imaging is based on a mathematical model of an ellipsoid. Thus principal directions of diffusion and the magnitude of diffusion along those directions can be calculated. Diffusion tensor tractography is an innovative application of the diffusion tensor method which can access the pathways of neuronal fibers. However, neuronal tissue is a highly heterogeneous structure on various scales and the Gaussian distribution has only been adapted for free diffusion in a fluid that is uniform and sufficiently large. Complicated wall structures exist in the neuronal tissue, and the Gaussian distribution model does not reflect the existence of a large number of compartments and nerve tracts, particularly in the central nervous system. Therefore, instead of a simple Gaussian distribution model, measurement of the probability distribution of a detailed water molecule is necessary. One method is q-space imaging (QSI). QSI is performed by measuring a large amount of diffusion encoding and can provide the probability density function of individual water molecules. Although QSI is theoretically superior to conventional Gaussian distribution analysis, one limitation of QSI is the long acquisition time due to the large sampling number. The concept of kurtosis is another method to evaluate non-Gaussianity. Kurtosis is a quantity that reflects a gap between the diffusion distribution of a water molecule in vivo and the Gaussian distribution, and can be calculated from datasets of relatively few diffusion encoding elements compared to QSI. Thus, a rather short acquisition time is required for kurtosis. Recently, other innovative applications of non-Gaussian diffusion have been introduced including neurite orientation dispersion and density imaging (NODDI) which is a model-based diffusion technique that allows for the quantification of specific microstructural features directly related to neuronal morphology. These novel techniques will provide useful information on tissue microstructure not only in the scientific research but also in the clinical practice.

DOI： 10.7887/jcns.25.402

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