Faculty Profiles - KAWAZU Toshiyuki

Value of contrast-enhanced magnetic resonance imaging in differentiation of hemangiomas front lymphangiomas in the oral and maxillofacial region Reviewed

K Yonetsu, E Nakayama, T Kawazu, S Kanda, S Ozeki, M Shinohara

ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY ORAL RADIOLOGY AND ENDODONTICS 88 ( 4 ) 496 - 500 1999.10

Language：English Publishing type：Article, review, commentary, editorial, etc. (scientific journal) Publisher：MOSBY-YEAR BOOK INC

Objective. The purpose of this study was to investigate the ability of contrast-enhanced magnetic resonance imaging to differentiate hemangioma from lymphangioma in the oral and maxillofacial region.
Study design. Contrast-enhanced magnetic resonance imaging was performed in 20 patients (21 masses: 17 hemangiomas and 4 lymphangiomas) through use of either a 0.2-T permanent system or a 0.5-T superconductive system and spin-echo pulse sequences.
Results. After intravenous administration of contrast medium, enhancement was observed in all hemangiomas in areas corresponding to those with high signal on T-2-weighted images. Unequivocally increased signal was observed in 10 masses, and slightly increased signal was observed in 7 masses. On the other hand, none of the lymphangiomas showed an enhancing mass on contrast-enhanced T-1-weighted images.
Conclusions. Although contrast-enhanced T-1-weighted imaging may not improve delineation of masses in all cases, it can be used to differentiate between deep hemangiomas and lymphangiomas.

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ニューラルネットワークによる頸部リンパ節転移診断支援の有効性の検討 ROC曲線をもちいた支援効果の検討

荒木和之, 三輪邦弘, 花澤智美, 松田幸子, 山本実佳, 田谷あつ子, 河津俊幸, 岡野友宏

歯科放射線 39 ( 3 ) 179 - 180 1999.9

Physical evaluation of a system for direct digital intra-oral radiography based on a charge-coupled device

K Yoshiura, HC Stamatakis, U Welander, WD McDavid, XQ Shi, S Ban, T Kawazu, M Tatsumi, S Kanda

DENTOMAXILLOFACIAL RADIOLOGY 28 ( 5 ) 277 - 283 1999.9

Language：English Publisher：STOCKTON PRESS

Objectives: To determine technical properties of a direct digital intra-oral radiographic system, the Dixel(R)(J Morita Corporation, Kyoto, Japan).
Methods: A dose response function and the dark current were calculated from two series of exposures to a homogeneous radiation field. The line spread function (LSF) and the modulation transfer function (MTF) were determined from radiographs of an edge. The noise power spectrum (NPS) was determined at three exposures from radiographs exposed to homogeneous radiation fields. Noise equivalent quanta (NEQ) were calculated from the one-dimensional NPS and the MTF. The detective quantum efficiency (DQE) was determined from the NEQ and a representative value of the photon fluence. Signal-to-noise ratios (SNR) were calculated from the NEQs and different signal contrasts.
Results: The dose response function demonstrated a slight curvature. There was no effect of the dark current. NPS ranged from 10(-5)-10(-7) mm(2) depending on exposure and frequency. At a peak of about 2 cycles/mm the DQE is on an average about 30 per cent. SNRs are favorable.
Conclusion: The technical properties found in this study indicate that the Dixel(R)system is suitable for intra-oral dental radiography.

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Prediction of Perceptibility Curves of direct digital intraoral radiographic systems

K Yoshiura, HC Stamatakis, U Welander, WD McDavid, XQ Shi, S Ban, T Kawazu, T Chikui, S Kanda

DENTOMAXILLOFACIAL RADIOLOGY 28 ( 4 ) 224 - 231 1999.7

Language：English Publisher：STOCKTON PRESS

Objectives: To derive and test a method to predict Perceptibility Curves (PCs) for direct digital intraoral radiographic systems.
Methods: A test object was used to determine the performance of an average observer with respect to the threshold contrast and internal noise of the human visual system. These data were combined with system parameters to predict PCs mathematically.
Results: Data on the performance of an average observer could be defined to obtain values of the effective threshold contrast as a function of background gray level. This function combined with the gamma-value of the system predicted PCs that agreed well with PCs obtained in the conventional way.
Conclusion: It is possible to predict PCs from a limited number of system parameters together with predetermined data on an average observer.

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湯浅賢治, 河津俊幸, 中野敏昭

映像情報 31 ( 8 ) 463 - 466 1999.4

The change of CT and US findings of cervical lymphadenopathy in oral squamous cell carcinoma before and after preoperative chemoradiotherapy

Toshiyuki Kawazu, Kenji Yuasa, Shigenobu Kanda, Satoru Ozeki, Masanori Shinohara

Japan Society for Oral Tumors 11 ( 3 ) 135 - 142 1999

The change of CT and US findings of cervical lymphadenopathy in oral squamous cell carcinoma before and after preoperative chemoradiotherapy

KAWAZU Toshiyuki, YUASA Kenji, KANDA Shigenobu, OZEKI Satoru, SHINOHARA Masanori

11 ( 3 ) 135 - 142 1999

ニューラルネットワークによるエナメル上皮腫と歯原性角化嚢胞の画像診断への応用

河津俊幸, 荒木和之, 吉浦一紀, 大関悟, 篠原正徳, 神田重信

日本口腔科学会雑誌 47 ( 5 ) 661 - 661 1998.12

エナメル上皮腫と歯原性角化嚢胞の画像診断学的特徴 CT-axial像の皮質骨所見

河津俊幸, 吉浦一紀, 荒木和之, 神田重信

歯科放射線 38 ( 増刊 ) 57 - 57 1998.9

Mucoepidermoid carcinoma in the mandible - Findings of panoramic radiography and computed tomography

M Inagaki, K Yuasa, E Nakayama, T Kawazu, T Chikui, S Kanda, H Yoshikawa, S Nakamura, M Shinohara

ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY ORAL RADIOLOGY AND ENDODONTICS 85 ( 5 ) 613 - 618 1998.5

Language：English Publisher：MOSBY-YEAR BOOK INC

Six patients with mucoepidermoid carcinoma in the mandible were studied with both panoramic radiography and computed tomography. Lesion shape and margin were evaluated on panoramic radiography, and bony expansion and cortical plate destruction were evaluated on computed tomography. In addition, a possible correlation among radiographic findings, histologic findings, and prognosis was investigated. Lesions found on panoramic radiography were classified into three types; each type pertained to two of the six patients. The lesion types were as follows: cystic, characterized by a large, cystic radiolucent area; rarefying, characterized by rarefying changes of the trabeculae; and infiltrative, characterized by a central ill-defined area of bony destruction. The results show that computed tomography is useful in the identification of tumor extent, bony expansion, and cortical plate destruction resulting from tumors. None of the patients whose lesions were of the cystic or rarefying type showed evidence of disease after surgery. In contrast, both of the patients whose lesions were of the infiltrative type died of their tumors. Histologic findings of the cystic and rarefying types showed tumors that were well-differentiated or moderately weil-differentiated, whereas findings of the infiltrative type showed poorly differentiated tumors. Radiographic findings correlated with histologic findings and prognosis of mucoepidermoid carcinoma in the mandible in this limited series.

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