Faculty Profiles - NAGANAWA, Shinji

Papers - NAGANAWA, Shinji

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第64回日本医学放射線学会学術集会　イメージインタープリテーションセッション症例出題集

長縄慎二、原真咲

日本医学放射線学会誌別冊付録 Vol. 65 ( 2 ) page： 1-14 2005

第３３回日本磁気共鳴医学会大会にみるBody diffusionの動向

長縄慎二

Innervision Vol. 20 ( 12 ) page： 112 2005

高磁場MRI

長縄慎二

日本医師会雑誌 Vol. 134 ( 9 ) page： 1722-1726 2005

超高磁場MRIのインパクト(3T MRIをふくめて）脳以外への活用方法

長縄慎二

日独医報 Vol. 50 ( 3 ) page： 479-489 2005

前立腺癌，子宮頸癌におけるADC測定の意義

長縄慎二

画像診断 Vol. 25 ( 6 ) page： 737-743 2005

Authorship：Lead author Language：Japanese

DWIBSにおいての癌描出のメカニズムは十分に把握されておらず，基礎的な検討としても，現時点での臨床的な課題としても，さまざまな種類の癌のADCを測定することが重要である．前立腺癌と子宮頸癌におけるADC計測の結果と臨床的な位置付けを1.5T，3Tでの結果に基づいて解説する

電子ポスター(Cypos)元年　JRC2005を振り返って

石垣武男　藤田広志　深津博　長縄慎二　片渕哲朗　原武史

Innervision Vol. 20 ( 7 ) page： 28-33 2005

第64回日本医学放射線学会学術集会　イメージインタープリテーションセッション症例出題集

長縄慎二、原真咲

日本医学放射線学会誌別冊付録 Vol. 65 ( 3 ) page： 1-28 2005

Serial evaluation of diffusion tensor brain fiber tracking in a patient with severe diffuse axonal injury. Reviewed

Naganawa S, Sato C, Ishihra S, Kumada H, Ishigaki T, Miura S, Watanabe M, Maruyama K, Takizawa O

AJNR Am J Neuroradiol Vol. 25 ( 9 ) page： 1553-1556 2004.10

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

Serial evaluation of diffusion tensor brain fiber tracking was performed in a 27-year-old female patient with diffuse axonal injury after a traffic accident. Although the result of brain fiber tracking was not necessarily parallel to her clinical symptoms, it may have predicted the neurologic prognosis.

Rad Talk ISMRM2004

長縄慎二

Rad Fan Vol. 2 ( 6 ) page： 47-56 2004.10

High-speed imaging at 3 Tesla: a technical and clinical review with an emphasis on whole-brain 3D imaging. Reviewed

Naganawa S, Kawai H, Fukatsu H, Ishigaki T, Komada T, Maruyama K, Takizawa O

Magn Reson Med Sci Vol. 3 ( 4 ) page： 177-187 2004

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

Improvements to the inherently high specific-absorption rate (SAR) of high-speed imaging at 3T are necessary in order to render this method clinically feasible. Various efforts have been undertaken to improve the associated hardware and software. In this review, we focus on whole-brain isotropic 3D imaging with a turbo spin-echo sequence with variable flip-angle echo trains (3D-TSE-VFL) and present its technical and clinical features. This sequence can be used to acquire images of various contrasts including T2-weighted, fat-suppressed T2-weighted, fluid-attenuated inversion recovery (FLAIR), fat-suppressed FLAIR, and STIR (short tau inversion recovery). Various aspects of 3D-TSE-VFL are discussed, including CSF (cerebrospinal fluid) and metal artifacts, STIR contrast, small-part visualization other than brain, and the possibility of serial subtraction. Some images from clinical cases are presented.

MR imaging of gastric cancer in vitro: accuracy of invasion depth diagnosis.

Sato C, Naganawa S, Kumada H, Miura S, Ishigaki T

Eur Radiol Vol. 14 ( 9 ) page： 1543-1549 2004

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

The purpose of this study was to evaluate the accuracy of grading cancerous invasion of the gastric wall in vitro using magnetic resonance (MR) imaging. Twelve specimens of gastric carcinoma were examined at 1.5-T using a small, loop surface coil. They were imaged within 2 days of fixation in formalin. The field of view was 30 mm; the matrix size was 256x256, and the section thickness was 2 mm. T1-weighted, T2-weighted and short inversion time inversion recovery (STIR) images were obtained. Two radiologists evaluated the MR images independently, and in discrepant cases, consensus was obtained through discussion. Findings on MR images were compared with histopathologic findings. All T1-weighted, T2-weighted and STIR images depicted the normal gastric wall as consisting of six layers. STIR images depicted normal six layers most clearly. Histologically, the cancerous invasion was found to extend into the mucosa in 4 of the 12 specimens, the submucosa in 3, the muscularis propria in 2, the subserosa in 2 and the serosa in 1. The grading by MR imaging matched the histopathologic findings for all 12 tumors. The overall accuracy was 100%. Thus, MR imaging in vitro was sufficiently accurate for grading cancerous invasion of the gastric wall.

Flow ghost artifact in slice-encoding direction mimicking vestibular schwannoma in contrast-enhanced 3D spoiled gradient-echo sequence. Reviewed

Naganawa S, Koshikawa T, Fukatsu H, Ishigaki T, Aoki I

Eur Radiol Vol. 14 ( 3 ) page： 496-499 2004

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

The value of MR imaging by post-contrast T1-weighted 3D spoiled gradient-echo (3D SPGR) is well established for the detection of small vestibular schwannomas in the cerebellopontine angle region. We describe a case in which a flow ghost artifact in the slice-encoding direction mimicked a vestibular schwannoma and heavily T2-weighted MR cisternography and multiplanar reconstruction images helped us to reach the correct diagnosis. In addition, we conducted a volunteer study to demonstrate that changing the k-space trajectory can reduce this artifact in post-contrast 3D SPGR images.

Pre-surgical mapping of primary motor cortex by functional MRI at 3 T: effects of intravenous administration of Gd-DTPA. Reviewed

Naganawa S, Nihashi T, Fukatsu H, Ishigaki T, Aoki I

Eur Radiol Vol. 14 ( 1 ) page： 112-114 2004

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

The functional magnetic resonance imaging (fMRI) is often performed at the end of a routine MRI examination during which, dependent on the clinical indication, contrast agent has been administered; however, the effects of Gd-DTPA injection on the results of blood oxygenation level dependent (BOLD)-fMRI remain unknown. The present study was conducted to investigate the effects of the intravenous administration of Gd-DTPA on the results of pre-surgical localization of the primary motor cortex by BOLD-fMRI at 3 T. Eight normal subjects were included in this study. After the anatomical scans, pre- and post-contrast fMRI scanning was performed. The number of significantly activated voxels and the mean percentage signal change were compared. The mean number of significantly activated voxels was 115.0+/-27.0 in pre-contrast runs and 90.8+/-27.1 in post-contrast runs (mean value of all 8 volunteers+/-standard deviation; p<0.05). The mean mean percentage signal change was 4.07+/-0.39 in pre-contrast runs and 3.86+/-1.91 in post-contrast runs ( p=0.16). Pre-surgical localization of the motor area by BOLD-fMRI should be performed before the administration of Gd contrast material.

Optimization of diffusion-tensor MR imaging data acquisition parameters for brain fiber tracking using parallel imaging at 3 T. Reviewed

Naganawa S, Koshikawa T, Kawai H, Fukatsu H, Ishigaki T, Maruyama K, Takizawa O

Eur Radiol Vol. 14 ( 2 ) page： 234-238 2004

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

The purpose of this study was to optimize the parameters of diffusion-tensor magnetic resonance imaging (DT MRI) for brain fiber tracking using a slice thickness of 2 mm, a resolution advantage allowed by the high signal-to-noise ratio at 3 T, combined with an 8-channel phased-array head coil. The b-factor, number of motion probing gradient (MPG) directions, and number of averages were varied, and the results of brain fiber tracking for the pyramidal tract and trigeminal nerve were compared qualitatively and quantitatively. The DT MRI data sufficient for brain fiber tracking in healthy subjects can be obtained in <2 min with a 2-mm slice thickness, 700-s/mm2 b-factor, 6 MPG directions, and no averaging (number of averages=1).

Enlarged endolymphatic duct and sac syndrome: relationship between MR findings and genotype of mutation in Pendred syndrome gene. Reviewed

Naganawa S, Koshikawa T, Fukatsu H, Ishigaki T, Sato E, Sugiura M, Yoshino T, Nakashima T

Magn Reson Imaging Vol. 22 ( 1 ) page： 25-30 2004

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

Pendred syndrome (PDS) is characterized by profound deafness in childhood, positive perchlorate challenge, and goiter. PDS is often associated with enlarged endolymphatic duct and sac (EEDS), and recently, PDS gene mutations have been reported even in those patients with EEDS without classic Pendred syndrome. In a previous report, the number of mutant alleles was correlated with the degree of subclinical thyroid abnormality, but not with hearing loss, in patients with missense mutation H723R. It also has been reported that the hearing loss in EEDS was not correlated with the EEDS volume, cochlear modiolar area, or signal intensity of the endolymphatic sac. We evaluated the correlations between the number of mutant alleles and these parameters in patients with EEDS to investigate the mechanisms underlying this condition. The study group was comprised of 16 Japanese patients with EEDS diagnosed by MR imaging. The H723R mutation was homozygous in six patients and heterozygous in six patients, with no mutation found in four patients. The modiolar area, EEDS volume, and signal intensity ratio (sac signal/cerebrospinal fluid signal) were not significantly correlated with the number of mutant alleles. PDS gene mutations may not be the only cause of EEDS, and the mechanisms underlying EEDS remain unclear.

Whole-brain vascular reactivity measured by fMRI using hyperventilation and breath-holding tasks: efficacy of 3D prospective acquisition correction (3D-PACE) for head motion. Reviewed

Naganawa S, Koshikawa T, Fukatsu H, Ishigaki T, Maruyama K, Takizawa O

Eur Radiol Vol. 14 ( 8 ) page： 1484-1488 2004

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

Functional MR imaging (fMRI) study using hyperventilation and breath-holding task has been reported to be one of the non-invasive methods to examine whole-brain vascular reactivity. The purpose of this study was to evaluate the efficacy of a method for 3D prospective detection and correction of head motion (3D-PACE) in a study of whole-brain vascular reactivity using hyperventilation and breath-holding tasks. Eight healthy volunteers were scanned using an fMRI protocol of hyperventilation and breath-holding task blocks at 3 T in separate runs with and without 3D-PACE. In two subjects, two more runs with and without 3D-PACE were repeated. The mean total number of activated voxels +/- standard deviation was 26,405.3+/-1,822.2 in the run with 3D-PACE and 17,329.9+/-2,766.3 in the run without 3D-PACE ( P<0.05), although there is some intersubject variation regarding the effect of 3D-PACE. In the two subjects whose performed two more runs, the number of activated voxels were smaller in the run without 3D-PACE than even in the run with 3D-PACE performed later. We conclude that 3D-PACE is beneficial for fMRI studies of whole-brain vascular reactivity induced by hyperventilation and breath-holding.

Comparison of flow artifacts between 2D-FLAIR and 3D-FLAIR sequences at 3 T. Reviewed

Naganawa S, Koshikawa T, Nakamura T, Kawai H, Fukatsu H, Ishigaki T, Komada T, Maruyama K, Takizawa O

Eur Radiol Vol. 14 ( 10 ) page： 1901-1908 2004

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal)

It has been reported that 3D-FLAIR can reduce the flow artifact resulting from cerebrospinal fluid (CSF) at 1.5 T compared to 2D-FLAIR. Flow-related artifacts tend to be worse at 3 T than at 1.5 T. The purpose of this study was to compare the CSF flow artifacts of 2D-FLAIR and 3D-FLAIR sequences at 3 T in eight healthy volunteers. The grade of CSF-related artifacts were scored through observing the perimedullary cistern, cerebellopontine angle cisterns, fourth ventricule, prepontine cistern, suprasellar cistern, ambient cisterns, sylvian fissures, third ventricle and lateral ventricles. Grading was performed on either axial or sagittal images. The CSF in-flow artifact scores were significantly higher on axial 2D-FLAIR than on axial 3D-FLAIR MPR images in all areas except the bilateral sylvian fissures, and higher on sagittal 2D-FLAIR than on sagittal 3D-FLAIR MPR images in perimedullary, bilateral CP angle and suprasellar cisterns. The CSF-related flow artifacts were significantly reduced by 3D-FLAIR, while structures in the cistern were depicted more clearly, even at 3 T. Further study is necessary to compare the clinical efficacy between 2D-FLAIR and 3D-FLAIR in depicting subtle abnormalities.

MRIの最新トッピックス　3T MRIの臨床

長縄慎二

映像情報メディカル Vol. 36 page： 1056-1060 2004

頭頚部画像診断に必要不可欠な臨床画像解剖（１）側頭骨　（内耳、内耳道）

長縄慎二

画像診断 Vol. 24 ( 11 ) page： 2-4 2004

Magnetic resonance imaging of endolymphatic sac in acute low-tone sensorineural hearing loss without vertigo. Reviewed

Sugiura M, Naganawa S, Nakashima T, Misawa H, Nakamura T

ORL J Otorhinolaryngol Relat Spec Vol. 65 ( 5 ) page： 254-260 2003

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

The etiology of acute low-tone sensorineural hearing loss (ALHL) may be associated with deteriorated function of the endolymphatic sac. Using magnetic resonance (MR) imaging on a 1.5-tesla MR system, we evaluated the frequency of visualization and contrast enhancement of the endolymphatic sac in 25 patients (9 men and 16 women; age range 11-64 years) with ALHL and 21 control subjects. The present study demonstrated that the frequency of visualization and enhancement of the endolymphatic sac in patients with ALHL was not significantly higher than in control subjects.

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Papers - NAGANAWA, Shinji