Faculty Profiles - NAGANAWA, Shinji

Papers - NAGANAWA, Shinji

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Fetal sacrococcygeal teratoma visualized by ultra-fast T2 weighted magnetic resonance imaging. Reviewed

Okamura M, Kurauchi O, Itakura A, Naganawa S, Watanabe Y, Mizutani S

Int J Gynaecol Obstet Vol. 65 ( 2 ) page： 191-193 1999

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

We report here a fetal sacrococcygeal teratoma found at 26 weeks of gestation. An ultra-fast T2 weighted imaging method enables the clear visualization of morphological details of the fetus without motion artifacts. Complete surgical resection was performed immediately after cesarean birth, and no evidence of tumor recurrence was confirmed at 1 year of age.

High-resolution MR cisternography of the cerebellopontine angle, obtained with a three-dimensional fast asymmetric spin-echo sequence in a 0.35-T open MR imaging unit. Reviewed

Naganawa S, Ito T, Iwayama E, Fukatsu H, Ishigaki T

AJNR Am J Neuroradiol Vol. 20 ( 6 ) page： 1143-1147 1999

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

High-resolution MR cisternography performed with 3D fast asymmetric spin-echo imaging (3D fast spin-echo with an ultra-long echo train length and asymmetric Fourier imaging) was optimized in a 0.35-T open MR imaging unit. The 0.35- and 1.5-T images of the two volunteers and three patients with acoustic schwannomas were then compared. The optimal parameters for images obtained by 3D fast asymmetric spin-echo imaging at 0.35 T were as follows: field of view, 15 cm; matrix, 256 x 256 x 40; section thickness, 1 mm; echo train length, 76; and imaging time, 10 minutes 44 seconds. Scans obtained from both normal volunteers showed the facial, cochlear, and superior and inferior vestibular nerves separately in the internal auditory canal on both 0.35- and 1.5-T images. All three acoustic schwannomas were depicted on both 0.35- and 1.5-T images. Screening for disease at the cerebellopontine angle and in the internal auditory canal, without the administration of contrast material on a low-field open MR imaging unit and within a clinically acceptable imaging time, may be possible. Further controlled prospective studies are required, however, before implementation on a wide basis. If proved effective, this may be of particular value for reducing healthcare costs and for imaging claustrophobic and pediatric patients in an open system.

Magnitude subtraction vs. complex subtraction in dynamic contrast-enhanced 3D-MR angiography: basic experiments and clinical evaluation. Reviewed

Naganawa S, Ito T, Iwayama E, Fukatsu H, Ishiguchi T, Ishigaki T, Ichinose N

J Magn Reson Imaging Vol. 10 ( 5 ) page： 813-820 1999

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

Magnitude subtraction and complex subtraction in dynamic contrast-enhanced three-dimensional magnetic resonance (3D-MR) angiography were compared using a phantom and 23 human subjects. In phantom studies, complex subtraction showed far better performance than magnitude subtraction, especially for longer echo times, with thicker slices, and without fat suppression. With complex subtraction, non-fat-suppressed studies showed contrast-to-noise ratios comparable to those in fat-suppressed studies. In human subjects, complex subtraction was superior to magnitude subtraction in 9 subjects, but comparable to magnitude subtraction in 14 subjects. There were no cases in which magnitude subtraction was superior to complex subtraction. Although the differences observed in human studies when complex subtraction was applied with thinner slices, shorter echo times, and the fat-suppression technique were not as pronounced as those seen in phantom studies, complex subtraction should be performed in dynamic contrast-enhanced 3D-MR angiography because there are no drawbacks in complex subtraction. Further research is necessary to assess the feasibility of dynamic contrast-enhanced 3D-MR angiography without fat suppression in human subjects using complex subtraction, as suggested by the results of phantom studies. If it is found to be feasible, dynamic contrast-enhanced 3D-MR angiography without fat suppression using complex subtraction may prove to be a robust technique that eliminates the need for shimming and can reduce the acquisition time. J. Magn. Reson. Imaging 1999;10:813-820.

MR imaging of the cochlear modiolus: area measurement in healthy subjects and in patients with a large endolymphatic duct and sac. Reviewed

Naganawa S, Ito T, Iwayama E, Fukatsu H, Ishigaki T, Nakashima T, Ichinose N

Radiology Vol. 213 ( 3 ) page： 819-823 1999

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

PURPOSE: To evaluate the cochlear modiolus with thin-section magnetic resonance (MR) imaging in healthy subjects and patients with a large endolymphatic duct and sac, and to assess whether the cochlea is normal or abnormal in patients with a large endolymphatic duct and sac. MATERIALS AND METHODS: MR images were obtained in 10 ears in five volunteers (group 1), 40 ears in 20 patients with bilateral sensory hearing loss (group 2), three ears in two patients with Mondini malformation (group 3), and 12 ears in seven patients with a large endolymphatic duct and sac (group 4). RESULTS: In groups 1 and 2, all modiolar areas were larger than 4.0 mm2. In group 3, each modiolus was smaller than 2.0 mm2. In group 4, modiolar areas were smaller than 2.0 mm2 in eight ears and were larger than 4.0 mm2 in four ears. CONCLUSION: Findings in this study confirm that a large endolymphatic duct and sac is frequently associated with modiolar deficiency, but the modiolar area is normal in some cases. This result does not support the recently proposed hypothesis that hearing loss with a large endolymphatic duct and sac is caused by the transmission of subarachnoid pressure forces into the labyrinth through a deficient modiolus.

MR cisternography of the cerebellopontine angle using a 3D fast spin echo sequence

Naganawa S, Ito T, Iwayama E, Fukatsu F, Ishigaki T

Medical Imaging International Vol. 9 page： 16-18 1999

Three-dimensional Fast spin echo MR of inner ear

American Journal of Neuroradiology Vol. 19 page： 739-741 1998

Inter observer agreement in sonographic diagnosis of breast tumors

European Journal of ultrasound Vol. 8 page： 25-31 1998

MR imaging of the inner ear

Radiology Vol. 208 page： 679-685 1998

Interobserver agreement in sonographic diagnosis of breast tumors. Reviewed

Shimamoto K, Sawaki A, Ikede M, Satake H, Naganawa S, Tadokoro M, Isomura T, Hirota H, Ishigaki T

Eur J Ultrasound Vol. 8 ( 1 ) page： 25-31 1998

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

OBJECTIVE: To evaluate interobserver agreement in the interpretation of breast ultrasonography. METHODS: 55 breast masses (30 benign, 24 malignant) were interpreted by seven radiologists using a CRT viewing station. US criteria for differentiating between benign and malignant lesions included shape, border, boundary echoes, internal echoes, posterior echoes, and bilateral shadows. Each criterion and the observers' final impression was scored using the 5-point rating scales. For analyzing interobserver agreement, the kappa (kappa) values were employed. RESULTS: The kappa values of shape and posterior echoes were significantly higher than those of the other four criteria (P<0.05). Agreement was intermediate in border and internal echoes, and was low in boundary echoes and bilateral shadows. Agreement in the senior group (four observers) was relatively higher than that in the junior group (three observers) for all criteria but for internal echoes. Easily-diagnosed cases showed significantly higher kappa values compared with more ambiguous cases (P<0.05). CONCLUSION: Interobserver agreement in shape and posterior echoes was significantly higher than those of the other four criteria. Agreement was significantly dependent on case difficulty.Copyright 1998 Elsevier Science Ireland Ltd.

Three-dimensional fast spin-echo MR of the inner ear: ultra-long echo train length and half-Fourier technique.

Naganawa S, Itoh T, Fukatsu H, Ishigaki T, Nakashima T, Kassai Y, Miyazaki M, Takai H

AJNR Am J Neuroradiol Vol. 19 ( 4 ) page： 739-741 1998

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

We compared the image quality of the newly developed ultra-long echo train length (ETL) 3-D fast spin-echo (FSE) and half-Fourier technique, which is performed in less than 3 minutes, with the conventional 3D-FSE imaging technique, which takes 15 minutes, in assessing MR examinations of the inner ear. The new method's images were almost comparable to the conventional 3D-FSE images in depicting anatomic details and pathologic findings. Implementation of the ultra-long ETL and half-Fourier 3D-FSE imaging technique enables acquisition of inner ear MR studies in a vastly reduced time and with high spatial resolution without significant penalty, opening the possibility for low-cost screening of acoustic tumors without contrast enhancement in less than 3 minutes.

Screening helical CT for mass screening of lung cancer: application of low-dose and single-breath-hold scanning. Reviewed

Itoh S, Ikeda M, Isomura T, Endo T, Yamakawa K, Itoh K, Naganawa S, Maruyama K, Ishigaki T

Radiat Med Vol. 16 ( 2 ) page： 75-83 1998

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

PURPOSE: To investigate the usefulness of helical CT with low-dose and single-breath-hold scanning for lung cancer screening. MATERIALS AND METHODS: Twenty-four helical CT scans of the lung were performed using various parameters in 10 healthy volunteers. The effects of tube current and pitch were evaluated by assessment of image quality and detection of simulated nodules. Screening helical CT was performed at 120 kVp, 50 mA, 1 sec/rotation, 10 mm collimation, and a pitch of 2.0 in 110 patients. The ability of this method to detect nodules and masses, focal parenchymal opacities, and diffuse fibrotic changes was evaluated using conventional CT as the gold standard. RESULTS: A reduction in tube current to 50 mA did not significantly change the assessment of image quality or detection of simulated nodules. Although these factors were degraded by increasing the pitch, there was no significant difference between 1.5 and 2.0. Screening helical CT permitted the entire lung to be scanned with ease during a single-breath-hold in all patients. This method detected 177 of 196 nodules and masses (87 of 91 lesions greater than 5 mm in diameter), 54 of 57 focal parenchymal opacities, and 15 of 15 cases with fibrotic changes. CONCLUSION: Screening helical CT with low-dose and single-breath-hold scanning shows promise for lung cancer screening.

MR imaging of the inner ear: comparison of a three-dimensional fast spin-echo sequence with use of a dedicated quadrature-surface coil with a gadolinium-enhanced spoiled gradient-recalled sequence. Reviewed

Naganawa S, Ito T, Fukatsu H, Ishigaki T, Nakashima T, Ichinose N, Kassai Y, Miyazaki M

Radiology Vol. 208 ( 3 ) page： 679-685 1998

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

PURPOSE: To prospectively evaluate the sensitivity and specificity of magnetic resonance (MR) imaging in the inner ear with a long echo train, three-dimensional (3D), asymmetric Fourier-transform, fast spin-echo (SE) sequence with use of a dedicated quadrature-surface phased-array coil to detect vestibular schwannoma in the cerebellopontine angle and the internal auditory canal. MATERIALS AND METHODS: In 205 patients (410 ears) with ear symptoms, 1.5-T MR imaging was performed with unenhanced 3D asymmetric fast SE and gadolinium-enhanced 3D gradient-recalled (SPGR) sequences with use of a quadrature surface phased-array coil. The 3D asymmetric fast SE images were reviewed by two radiologists, with the gadolinium-enhanced 3D SPGR images used as the standard of reference. RESULTS: Nineteen lesions were detected in the 410 ears (diameter range, 2-30 mm; mean, 10.5 mm +/- 6.4 [standard deviation]; five lesions were smaller than 5 mm). With 3D asymmetric fast SE, sensitivity, specificity, and accuracy, respectively, were 100%, 99.5%, and 99.5% for observer 1 and 100%, 99.7%, and 99.8% for observer 2. CONCLUSION: The unenhanced 3D asymmetric fast SE sequence with a quadrature-surface phased-array coli allows the reliable detection of vestibular schwannoma in the cerebellopontine angle and internal auditory canal.

分岐型ステントグラフトを留置した腹部大動脈瘤の１例

岩井宏悦、石口恒男、鈴木耕次郎、新畑昌滋、長縄慎二、丸山邦弘、石垣武男、小林英昭、松下昌裕、櫻井恒久

映像情報メディカル Vol. 30 page： 753-755 1998

フェリデックス投与後のT1強調像が評価に有用であった2例

深津博、長縄慎二　岩山恵理子、石垣武男

映像情報メディカル Vol. 30 page： 1030-1032 1998

3D-fast spin echo法を用いた小脳橋角部のMR cisternography

映像情報メディカル Vol. 29 ( 6 ) page： 341-343 1997

Cerebral black blood MR angiography with the interleaved multi-slab three-dimensional fast spin echo sequence. Reviewed

Naganawa S, Ito T, Shimada H, Nagao R, Endo T, Uchiumi K, Ishigaki T

Radiat Med Vol. 15 ( 6 ) page： 385-388 1997

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

To overcome the disadvantages of conventional three-dimensional time-of-flight MR angiography (3D-TOF), such as saturation or intravoxel dephasing, black blood MR angiography (BB-MRA) using an interleaved multi-slab 3D fast spin echo sequence was developed and evaluated clinically. In major branches, the contrast-to-noise ratio of the flow was not as good as 3D-TOF in BB-MRA. However, in-plane slow flow and large aneurysm were visualized better on BB-MRA than on 3D-TOF. Furthermore, BB-MRA could provide wider coverage than 3D-TOF. BB-MRA using interleaved multi-slab 3D fast spin echo is now feasible and complementary to 3D-TOF.

著明な心、肺血管内進展を示した肺門部腫瘍の１例

河津省司、伊藤都紀子、加藤加代子、稲垣弘、長縄慎二、丸山邦弘、深津博、石口恒男、小林英敏、石垣武男、碓氷章彦、吉田光伸

映像情報メディカル Vol. 29 page： 1542-1545 1997

High speed and high resolution MR imaging og the inner ear asinng ultra-long echo train length 3D fast spin echo sequence and half Eonrier imaging

Proceedings of ISMRM page： 631 1996

MR imaging of the primary breast lymphoma

Breast Cancer Vol. 3 ( 3 ) page： 209-213 1996

従来型CT装置における造形剤投与法の腹部域での検討

映像情報メディカル Vol. 28 ( 3 ) page： 332-335 1996

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Papers - NAGANAWA, Shinji