Faculty Profiles - NAGANAWA, Shinji

Papers - NAGANAWA, Shinji

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MR hydrographyの臨床応用, 耳鼻科領域

長縄慎二、伊藤都紀子

画像診断 Vol. 19 ( 7 ) page： 755-763 1999.7

MR imaging of the cerebollo pontine argle using a 3D fast spin echo sequence

Medical Imaging International Vol. 9 ( 2 ) page： 16-19 1999

High-resolution MR cisternography of the cerefellopintine angle, of tired in a 0.35-T Open MR unit

American Journal of Neuro radiology(AJNR) Vol. 20 ( 6 ) page： 1143-1147 1999

Fetal sacrococcygesl terotoma visualized by ultrafast T₂ Wighted megnetic resonance imaging

International Journal of gynecology and obstetrics Vol. 65 page： 191-193 1999

MR hydrographyの臨床応用耳鼻科銭域

画像診断 Vol. 19 ( 7 ) page： 755-763 1999

High-resolution MR images of inner ear internal anatomy using a local gradient coil at 1.5 Tesla: correlation with histological specimen. Reviewed

Ito T, Naganawa S, Fukatsu H, Ishiguchi T, Ishigaki T, Kobayashi M, Kobayashi K, Ichinose N, Miyazaki M, Kassai Y

Radiat Med Vol. 17 ( 5 ) page： 343-347 1999

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

PURPOSE: To obtain high-resolution MR images of the inner ear at 1.5 Tesla with a local gradient coil and to correlate these images with the histological specimen. MATERIALS AND METHODS: All studies were performed on a 1.5 Tesla MR unit with a local gradient coil (23 mT/m, slew rate of 107 mT/m/ms). The cranio-facial region of a cadaver was examined using 3D-fast spin echo (FSE) imaging with the voxel size of 0.27 mm x 0.27 mm x 0.5 mm in 9 h 37 min. Two normal volunteers were examined with the same system using 3D-FSE imaging with the voxel size of 0.20 mm x 0.26 mm x 1.0 mm in 57 min. These images were correlated with the cadaver images and histological specimens. RESULTS: On cadaver images, internal structures such as the macula utriculi, macula sacculi, crista ampullaris, lamina spiralis ossea, ligamentum spirale cochleae, modiolus, scala tympani, scala vestibuli, and cochlear aqueduct were visualized. On the images of both volunteers, the same structures were visualized as on the cadaver images. CONCLUSIONS: This study confirmed that high-resolution MR images obtained at 1.5 Tesla can visualize inner ear internal anatomy. Knowledge obtained in this study may be of significant value for the diagnosis of pathology in the area of the inner ear.

High-resolution MR cisternography of the cerebellopontine angle: 2D versus 3D fast spin-echo sequences. Reviewed

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

AJNR Am J Neuroradiol Vol. 20 ( 5 ) page： 889-895 1999

Clinical evaluation of three-dimensional MR-cholangiopancreatography using three-dimensional Fourier transform fast asymmetric spin echo method (3DFT-FASE): usefulness of observation by multi-planar reconstruction. Reviewed

Yamakawa K, Naganawa S, Maruyama K, Kato T, Fukatsu H, Ishigaki T

Radiat Med Vol. 17 ( 1 ) page： 15-19 1999

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

MR-cholangiopancreatography (MRCP) is a new method that is non-invasive and permits volume data collection and three-dimensional expression. With the three-dimensional Fourier transform fast asymmetric spin echo (3DFT-FASE) method, a higher spatial resolution can be obtained both in-pain and in slice selecting direction. In this paper, the usefulness of this new technique is investigated in the clinical diagnosis of MIP images and MPR. The study was performed in 10 normal volunteers and 21 patients with abnormalities in the pancreas or bile-duct sustem. The study was done using a 1.5 Tesla super-conductive machine. The MRCP images were interpreted by three radiologists. In most cases good images were obtained. The additional clinical information provided by MPR was remarkably useful in cystic lesions, especially in mucinous cystic neoplasm of the pancreas. Even when the intestine overlapped the pancreas, it was possible to evaluate the pancreatic duct by MPR. Three-dimensional observation and clinically useful diagnosis were possible by utilizing the advantageds of the 3DFT-FASE method appears quite useful in clinical application.

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.

DOI： 10.1016/S0020-7292(98)00248-3

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.

DOI： 10.1148/radiology.213.3.r99dc05819

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

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

Three-dimensional Fast spin echo MR of inner ear

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

DOI： 10.1148/radiology.208.3.9722845

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