Kyushu University Academic Staff Educational and Research Activities Database
List of Reports
Kazunori Yoshiura Last modified date:2021.08.25

Professor / Division of Maxillofacial Diagnostic and Surgical Sciences / Department of Dental Science / Faculty of Dental Science

1. Kazunori Yoshiura, Miho Yamada, Hideo Okuda, Masahiro Izumi, Naoyuki Yamada, Takemitsu Matsuo, Motomasa Sasaki, Jun Cheng, Haruo Okabe, An extensive case of cherubism: A long term follow-up case, Oral Radiology, 10.1007/BF02347840, Vol.5, No.2, pp.1-9, 1989.12, The present paper describes the radiological features, including CT, of a case of cherubism followed for a relatively long period. The case demonstrated the active phase of the lesion, which progressed from grade 1 to grade 3 during a 6 year period. The radiographic signs, such as increased radiolucency, inflammatory signs and root resorption as well as laboratory data seemed to be important to diagnose the stage of cherubism and to predict the clinical course of the disease. © 1989 The Japanese Society of Dental Radiology..
2. Kazunori Yoshiura, Miho Yamada, Naoyuki Yamada, Tumor-like swelling in the parotid-masseteric region due to condylar involvement of osteomyelitis of the mandible: Report of three cases, Oral Radiology, 10.1007/BF02352581, Vol.6, No.2, pp.55-62, 1990.12, Mandibular osteomyelitis often causes infection of the masticator space. Recent studies have shown the value of computed tomography (CT) in the diagnosis of infection. CT occasionally also suggests its etiology. The present three cases of mandibular osteomyelitis showed condylar involvement which caused a tumor-like swelling in the parotid-masseteric region. In one case, the true cause of infection was unclear, even by computed tomography. In two of the three cases, sialography was performed, and it showed a unique extraglandular mass pattern. It was suggested from the results that sialography and/or CT-sialography should be performed to rule out the etiology of the infection from a parotid lesion, if the true cause of infection is unclear. © 1990 The Japanese Society of Dental Radiology..
3. Kazunori Yoshiura, Hiroshi Takahashi, Shuichi Fujita, Haruo Okabe, Naoyuki Yamada, Radiological and histological study of osteomyelitis of the jaws - Correlation between radiographic and histological patterns, Oral Radiology, 10.1007/BF02352579, Vol.6, No.2, pp.37-48, 1990.12, Fifty-six patients with maxillary and mandibular osteomyelitis were investigated radiologically and histopathologically. The radiographic changes were classified into 5 patterns: osteolytic, mixed, sclerosing, sequestrum and irregular trabeculation patterns. Osteomyelitis was classified into 3 histological types, based on the amount of bony trabeculae present. Type I bone consisted of severely sclerotic bone, type II bone had coarse trabeculae with fibrotic marrow spaces. In contrast, type III bone had thin trabeculae with occasional osteoblastemata. The correlations between the radiographic and histological patterns and differences between acute and chronic cases were examined. Acute cases were often of the osteolytic or sequestrum patterns, and had type I or II bone. Type II bone was the most common, and was found in all radiographic types. Type III bone was frequently seen in cases with an osteolytic or mixed radiographic pattern. It seemed that severely sclerotic bone with narrowed or occluded Haversian canals (type I bone) tended to develop following acute infection. A possible explanation of the relationship of 5 radiographic types is also discussed. © 1990 The Japanese Society of Dental Radiology..
4. Miho Yamada, Kazunori Yoshiura, Hideo Okuda, Masahiro Izumi, Hiroshi Ueno, Naoyuki Yamada, An analysis of the postoperative maxillary cyst using computed tomography, Oral Radiology, 10.1007/BF02347873, Vol.7, No.2, pp.21-30, 1991.12, The diagnostic value of computed tomography (CT) as compared with conventional radiographs in the study of postoperative maxillary cysts (POMC) in 64 patients (85 sides) was evaluated. Typical CT findings of POMC were of a unilocular or multilocular homogeneous soft tissue density mass with expansile bony resorption. A comparison between conventional radiographs and CT proved that CT could determine the location and multilocularity of the cyst, the status of the antral walls, and abnormalities of the other paranasal sinuses and adjacent structures more precisely than conventional radiographs. CT also facilitated the ability to predict the direction of extension of the lesion. In conclusion CT was indispensable for accurately diagnosing POMC. In some cases the inferior extension of the lesion should be examined by conventional radiography because this can be obscured by degradation caused by metal artefacts during CT. © 1991 The Japanese Society of Dental Radiology..
5. B SADO, K YOSHIURA, K YUASA, Y ARIJI, S KANDA, M OKA, T KATSUKI, MULTIMODALITY IMAGING OF CERVICOFACIAL ACTINOMYCOSIS, ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY ORAL RADIOLOGY AND ENDODONTICS, Vol.76, No.6, pp.772-782, 1993.12, Actinomycosis is an uncommon chronic disease usually caused by Actinomyces israelii. It affects the soft tissue mainly but sometimes spreads to involve salivary glands, bone, or even the skin of the face and neck. Five cases have been seen in our department. Several imaging modalities were used to assist in making the diagnosis. The cases are presented and the literature reviewed. Ultrasonography was found to be a useful diagnostic tool especially in developing the differential diagnosis..
6. Yoshiko Ariji, Eiichiro Ariji, Kazunori Yoshiura, Shigenobu Kanda, A study on contrast discrimination of CT images, Oral Radiology, 10.1007/BF02349098, Vol.9, No.1, pp.9-16, 1993.06, We investigated the range of differences in CT values by which radiologists could distinguish among tissues. The contrast discrimination thresholds and contrast discrimination ratios were determined. The test pattern consisted of a square CT film (12 cm in width and 6 cm in length). The film had a circular reference field and a circular test field. Each field was 1 cm in diameter with the distance between the two center being 6.5 cm. The reference fields were set at 60 or 100 H. U.. The test fields were changed and compared with the reference. The window width (WW) and the window level (WL) were set at 400 and 50 H. U. or 250 and 60 H. U.. The contrast dincrimination thresholds for ten observers ranged from 5.9 to 19.3 H. U., and the contrast discrimination ratios were from 11.5 to 21.3%. The effect of WW on contrast discrimination was analyzed for various WWs ranging from 200 to 1000 H. U.. Changes in WW produced no significant difference under the conditions of this investigation. © 1993 The Japanese Society of Dental Radiology..
7. E JARIJI, Y ARIJI, K YOSHIURA, S KIMURA, Y HORINOUCHI, S KANDA, ULTRASONOGRAPHIC EVALUATION OF INFLAMMATORY CHANGES IN THE MASSETER MUSCLE, ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY ORAL RADIOLOGY AND ENDODONTICS, Vol.78, No.6, pp.797-801, 1994.12, The ultrasongraphic images of 32 patients with inflammatory change in the masseteric region were investigated to clarify the characteristic findings and to evaluate the utility of ultrasonography. Inflamed muscles frequently demonstrated reduction of echo intensity and complete or partial absence of hyperechoic bands. The mean thickness of the masseter muscle on the unaffeted side was 8.06 mm, whereas that on on the affected side was 12.9 mm. Nine of 10 patients with heterogeneous hypoechoic area, but only 1 of 10 patients with homogeneous hypoechoic area, had received surgical treatment before ultrasonographic examination..
8. M SHIMIZU, K YOSHIURA, S KANDA, RADIOLOGICAL AND HISTOLOGICAL ANALYSIS OF THE STRUCTURAL-CHANGES IN THE RAT PAROTID-GLAND FOLLOWING RELEASE OF STENSENS DUCT OBSTRUCTION, DENTOMAXILLOFACIAL RADIOLOGY, Vol.23, No.4, pp.197-205, 1994.11, Sialography is the preferred method for diagnosis and treatment planning in obstructive sialadenitis. Although many experimental studies have reported changes following duct obstruction, those following release of obstruction have not been examined. The present study was undertaken to clarify: (1) the relationship between sialographic and histological changes; (2) the effects of duration and pressure of obstruction on gland recovery; (3) the possibility of establishing those sialographic features which indicate the prognosis for gland recovery. Stensen's ducts of rat parotid glands were obstructed for two different periods and at three different pressures in order to induce varying degrees of degenerative changes in the gland. The structural alterations resulting from release of obstruction were investigated by means of qualitative and quantitative microsialography and histology. Gland structure was assessed visually from the latter and classified into six groups: normal, recovery, and slight, moderate and severe degeneration and fibrous. Microsialograms were evaluated based on these groups. Qualitatively, microsialograms of the operated glands had a stricture in the obstructed region and dilation of the major ducts. Histological differences between recovery and degeneration glands were reflected in the morphology of peripheral ducts. The former showed a branch-like morphology similar to that of the normal group, and the latter contained small granule-like structures. Quantitatively, dilation of major ducts in the recovery group decreased compared with the other operated groups. There were no distinct sialographic features in the degeneration and fibrous groups which correlated with the degree of degeneration observed histologically. Duration and pressure of obstruction were highly predictive for prognosis for recovery. However, it was difficult to determine the prognosis for gland recovery from sialographic findings at the time of release of obstruction..
9. K YOSHIURA, T HIJIYA, E ARIJI, B SADO, E NAKAYAMA, Y HIGUCHI, S KUBO, S BAN, S KANDA, RADIOGRAPHIC PATTERNS OF OSTEOMYELITIS IN THE MANDIBLE PLAIN FILM CT CORRELATION, ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY ORAL RADIOLOGY AND ENDODONTICS, Vol.78, No.1, pp.116-124, 1994.07, Mandibular osteomyelitis often is associated with involvement of the masticator space. Assessment of mandibular osteomyelitis should therefore involve assessment of soft tissue involvement of the lesion. The purpose of this study was to clarify the relationship between computed tomography patterns and the presence of inflammation in soft tissues. Thirty-three cases diagnosed with osteomyelitis of the mandible were analyzed radiologically-with conventional radiographs and with computed tomography scans. Computed tomography patterns of osteomyelitis were classified into four types, lytic, mixed, sclerotic, and sequestrum patterns. Location, extent of the lesion, and change of the cortical plate were evaluated and compared with conventional radiographic findings. Mixed pattern cases displayed diffuse bone abnormalities, which sometimes were accompanied by cortical plate disruption and periosteal reaction. In addition, most mixed pattern cases showed soft tissue involvement, especially of the masseter muscle. Inflammation of the masseter muscle was found to be related to periosteal reaction and disruption of the buccal cortical plate. The data demonstrate a close interaction between cortical plate disruption and muscle inflammation. The extent of inflammation including soft tissue involvement was better appreciated with computed tomography in osteomyelitis, especially in mixed pattern cases..
10. JA XU, K YUASA, K YOSHIURA, S KANDA, QUANTITATIVE-ANALYSIS OF MASTICATORY MUSCLES USING COMPUTED-TOMOGRAPHY, DENTOMAXILLOFACIAL RADIOLOGY, Vol.23, No.3, pp.154-158, 1994.08, Quantitative information on the normal size range of the masticatory muscles needed for successful treatment of facial asymmetry is sparse. Our purpose in this study was to define morphological indicators for the volume of the masticatory muscles on CT. Cross-sectional areas and volumes of the masseter and medial pterygoid muscles were measured from CT scans of 65 patients. The muscles were scanned from origin to insertion and the maximum cross-sectional area (MCSA) and its location together with the total volume were determined. The mandibular foramen was used as a landmark to determine the location of MCSA. The location of MCSA of masseter muscle was centred 8 mm above the mandibular foramen, and that of medial pterygoid muscle at the foramen. The MCSA of both muscles was highly correlated with volume suggesting that this parameter might serve as an indicator of their volume. Knowledge of the location of the MCSA would facilitate its measurement, and so reduce radiation exposure. There was a positive correlation between the two muscles for both volume and MCSA. This finding could be relevant for future studies of the relationship between the morphology, biomechanics and pathology of the masticatory muscles..
11. Kazunori Yoshiura, Kunihiro Miwa, Eiichiro Ariji, Shigeo Ban, Shigenobu Kanda, Effects of surrounding conditions on boundary and internal echoes of simulated mass lesions: A phantom study, Oral Radiology, 10.1007/BF02348009, Vol.10, No.1, pp.1-9, 1994.06, Ultrasonography has been widely used in the maxillofacial region because of the ability to demonstrate pathological conditions in real time without radiation exposure. However, echo patterns of mass lesions vary with the surrounding tissue conditions. To examine the effects of the various surrounding conditions on depiction of such lesions on echograms, we constructed a model, an echo phantom consisting of an agar object, with or without scattering (methylcellulose) or absorptive (barium sulfate) material, and a corresponding surrounding medium. The object's boundary clarity decreased with increasing concentration of either the surrounding scattering or absorptive media, whereas the internal echo intensity of the object also decreased only with increasing concentration of the surrounding absorptive medium. The object with absorptive material produced peripheral echoes at the border. These results suggest that care should be taken when boundary echoes are evaluated as echo signs of lesions. © 1994 The Japanese Society of Dental Radiology..
13. E Nakayama, K Yonetsu, K Yoshiura, K Araki, S Kanda, K Yoshida, Diagnostic value of magnetic resonance imaging for malignant tumors in the oral and maxillofacial region, ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY ORAL RADIOLOGY AND ENDODONTICS, Vol.82, No.6, pp.691-697, 1996.12, The purpose of this study was to clarify the diagnostic value of magnetic resonance imaging for malignant tumors in the oral and maxillofacial region. Computed tomography and magnetic resonance images of 25 patients with malignant tumors of the oral and maxillofacial region were evaluated. Computed tomography scans were performed with intravenous contrast enhancement. A 0.2-Tesla (Hitachi Medical Corp., Tokyo, Japan) permanent magnetic resonance unit was used to obtain T1-, T2-, and proton-density-weighted images with spin-echo pulse sequences.
Gadolinium-diethylene-triamine-pentaacetic acid was administered in 11 cases. Severe artifacts influencing image interpretation were observed in 10 (40%) cases on computed tomography but only in 5 (20%) cases on magnetic resonance imaging. There was no difference in the detectability of bone invasion between images from the two systems. Contrast enhancement with gadolinium-diethylene-triamine-pentaacetic acid provided additional useful information in only 3 of 11 cases compared with nonenhanced magnetic resonance images. Malignant tumors showed a higher signal intensity than that of muscle on T2-weighted images in all cases and on proton-density-weighted images in 23 (92%) cases. On T1-weighted images, an intermediate signal intensity similar to that of muscle was seen in 16 (64%) cases and a hyperintense signal in 9 (36%) cases. There was poor correlation between signal intensity and pathologic diagnosis of the tumors. These results suggest that in cases with severe artifacts that disturb the interpretation of the images on computed tomography, magnetic resonance examinations are preferable for defining the exact extent of the primary lesion..
14. Y Ariji, E Ariji, K Yoshiura, S Kanda, Computed tomographic indices for maxillary sinus size in comparison with the sinus volume, DENTOMAXILLOFACIAL RADIOLOGY, Vol.25, No.1, pp.19-24, 1996.01, Objectives: To ascertain the normal range of maxillary sinus size and its changes with age on computed tomography (CT) and define convenient indices for sinus size, in addition, to examine the association of the height of the sinus floor with age and status of the dentition.
Methods. The transverse and anteroposterior dimensions of the normal maxillary sinuses in 107 subjects were measured on axial CT and the relationship between these values and the sinus volume analysed. The height of the sinus floor was obtained by measuring the vertical distance from the anterior nasal spine to the sinus floor.
Results. The mean transverse and anteroposterior widths of the normal adult maxillary sinuses were 2.70 (s.d., 0.60) cm and 3.56 (s.d., 0.47) cm, respectively. There was a close correlation with sinus volume which could be predicted well from the multiple regression formula. These values increased up to the age of 20 y, but then decreased. There was no significant difference between subjects aged 50-79 years with and without maxillary premolars and molars. The width of the adult sinus correlated with the interzygomatic buttress distance and body weight. The mean height of the adult maxillary sinus floor was 0.37 (s.d., 0.44) cm inferior to the anterior nasal spine. It correlated negatively with sinus volume and fell with age up to 20 y, then rose again. In adults, it was not significantly influenced by the dentition status, and rose in proportion to the decrease in the interzygomatic buttress distance, and body height and weight.
Conclusion. The transverse and anteroposterior widths of the maxillary sinus on axial CT are convenient indices for its size. The height of the sinus floor altered with changes in sinus volume, but was not directly influenced by the status of the dentition..
15. K Yoshiura, K Miwa, K Yuasa, K Tokumori, S Kanda, Y Higuchi, M Shinohara, Ultrasonographic texture characterization of salivary and neck masses using two-dimensional gray-scale clustering, DENTOMAXILLOFACIAL RADIOLOGY, Vol.26, No.6, pp.332-336, 1997.11, Objectives: To evaluate the clinical usefulness of texture analysis in ultrasonography (US) of head and neck masses.
Methods: Sixty-one cases with salivary or neck masses were examined by US with a linear 7.5MHz array. Images were digitized and quantitatively evaluated by two-dimensional gray-scale clustering using two texture indices, M and SD, as measures of coarseness and homogeneity respectively.
Results: Coarseness of Warthin's tumors was significantly higher than that of the other salivary tumors. Malignant lymphomas had finer texture values than other lymph node lesions.
Conclusions: Quantitative texture analysis appears to be a useful complement in diagnostic US..
16. K Yoshiura, K Tokumori, T Tanaka, N Shibaki, S Ban, K Araki, S Kanda, Two-dimensional gray-scale clustering for texture analysis, DENTOMAXILLOFACIAL RADIOLOGY, Vol.26, No.3, pp.152-160, 1997.05, Objectives: To develop a new quantitative method for the visual discrimination of image texture.
Methods: Two kinds of image phantoms were prepared, one for evaluating the effects of change in size and gray values of individual pixels (primitives) on perceived coarseness and the other for evaluating changes in groups of pixels (clusters on perceived heterogeneity. The phantom images were displayed on a CRT and presented to 11 observers who assessed heterogeneity and coarseness on a 10-point scale between -5 and +5. On the basis of the observers' results, a new texture analysis method termed two-dimensional gray-scale clustering analysis was developed and applied to measure quantitatively the texture of the phantoms, The results obtained were then compared with those of the visual evaluation
Results: The size of the primitives and the clusters greatly affected the visual evaluation of heterogeneity and coarseness. Changes in the gray value had only a slight effect. The intraobserver variation for heterogeneity was significantly larger than that for coarseness, Two-dimensional gray-scale clustering analysis could differentiate heterogeneity from coarseness, A high correlation was obtained between the visual evaluation and the quantitative data.
Conclusion: Quantitative two-dimensional gray-scale clustering analysis appears to be a useful means of texture analysis..
17. K Yoshiura, K Yuasa, O Tabata, K Araki, K Yonetsu, E Nakayama, S Kanda, M Shinohara, Y Higuchi, Reliability of ultrasonography and sialography in the diagnosis of Sjogren's syndrome, ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY ORAL RADIOLOGY AND ENDODONTICS, Vol.83, No.3, pp.400-407, 1997.03, Objectives. The purpose of this study was to evaluate quantitatively observer performance with ultrasonography and sialography in the diagnosis of parotid gland involvement of Sjogren's syndrome.
Study design. Sixty-four parotid gland sialograms and 65 ultrasonograms were prepared For observer performance experiments. They included both modalities in 24 Sjogren's syndrome and 19 nonspecific parotitis cases, 21 normal parotid gland sialograms, and 22 normal ultrasonograms in healthy volunteers. The images were randomly sequenced and presented to five observers who were asked to describe several findings and finally to determine the imaging diagnosis by ranking the abnormal features and the diagnosis on a five-point-rating scale. Observer performance was evaluated on the basis of the reliability of findings interpreted and the diagnostic accuracy of each modality from observers' rating scores.
Results. The diagnostic accuracy of sialography was very high, nearly perfect. The diagnostic accuracy of ultrasonography was lower than that of sialography, resulting from the lower incidence of characteristic findings in the disease groups and lower sensitivity on ultrasonography. In the differentiation of Sjogren's syndrome from the normal, however, the diagnostic accuracy of ultrasonography increased to 80% for all cases, and up to nearly 90% in the advanced sialographic stages.
Conclusion. Ultrasonography is useful for the diagnosis of Sjogren's syndrome in the advanced stages. Taking the noninvasiveness of this technique into account, we recommend first applying ultrasonography to the diagnosis of Sjogren's syndrome and performing sialography when no positive findings are detected on ultrasonography..
18. K Yoshiura, Y Higuchi, K Araki, M Shinohara, T Kawazu, K Yuasa, O Tabata, S Kanda, Morphologic analysis of odontogenic cysts with computed tomography, ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY ORAL RADIOLOGY AND ENDODONTICS, Vol.83, No.6, pp.712-718, 1997.06, Purpose. The purpose of this study was to analyze the effects of lesion site and epithelial keratinization on the morphologic characteristics of odontogenic cysts and clarify determinate factors for cyst morphology.
Material and methods. Computed tomographic images of 92 odontogenic cysts were analyzed: 31 primordial, 31 dentigerous and 30 radicular. Thirty-four cysts were located in the maxilla (6 primordial, 10 dentigerous, and 18 radicular) and 58 in the mandible (25 primordial, 21 dentigerous, and 12 radicular). Histologically, 31 cysts showed epithelial keratinization (18 primordial and 13 dentigerous). No keratinization was seen in radicular cysts. The morphologic features of cysts were assessed by measuring long length parallel to dental arch and short length vertical to it and calculating the long/short ratio. In addition, the computed tomography pattern of the cyst was classified into unilocular, lobulated, and multilocular patterns. Appearance of the sclerotic rim and surrounding cortex were classified into three and four patterns respectively to evaluate the developmental features of the cyst.
Results. As a whole, the long length of the primordial cysts was statistically larger than the other two cyst groups and resulted in a larger long/short ratio. Statistical differences of CT pattern were also seen among cyst groups. There was no preference in any cyst group for the appearance of the sclerotic rim and cortex. There were statistical differences between maxilla and mandible in short axis and long/short ratio. The maxillary cysts generally showed round shapes irrespective of their histologic characteristics. A multilocular pattern was more frequent in the keratinized group of mandibular primordial cysts. In dentigerous cysts, a multilocular pattern was seen only in the keratinized group and the long/short ratio was statistically larger; cyst shape was elliptical along the long axis.
Conclusion. Our results demonstrated morphologic differences of odontogenic cysts caused by lesion site and keratinization. The dentigerous cyst with predominant keratinization should be included in the primordial cyst (odontogenic keratocyst) group..
19. T Chikui, K Yonetsu, K Yoshiura, K Miwa, S Kanda, S Ozeki, M Shinohara, Imaging findings of lipomas in the orofacial region with CT, US, and MRI, ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY ORAL RADIOLOGY AND ENDODONTICS, Vol.84, No.1, pp.88-95, 1997.07, Objective. The aim of this study was to document retrospectively the imaging findings of lipomas with the use of computed tomography, ultrasonography, and magnetic resonance imaging.
Study design. Thirteen patients with 11 lipomas and 2 lipomatoses were evaluated. Eleven cases were examined by computed tomography, 9 by ultrasonography, and 3 by magnetic resonance imaging.
Results. Lipomas had a density ranging from -134 to -83 Hounsfield units, (mean -108) on the computed tomography images. The margins were ill defined in 9 of 10 cases. The superficial muscles were displaced externally in 8 cases and internally in 2 cases. With ultrasonography, 8 lesions were hypoechoic, and one was hyperechoic. All three lesions had a high signal intensity on both T-1- and T-2-weighted images.
Conclusions. Lipomas had a specific range of computed tomography Hounsfield unit values and also displaced the surrounding soft tissue. Although some variation in the ultrasonographic appearance was observed, the lesions tended to be hypoechoic. These findings may be useful for diagnosing lipomas in the orofacial region..
20. E Nakayama, E Ariji, M Shinohara, K Yoshiura, K Miwa, S Kanda, Computed tomography appearance of marked keratinization of metastatic cervical lymph nodes - A case report, ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY ORAL RADIOLOGY AND ENDODONTICS, Vol.84, No.3, pp.321-326, 1997.09, A case of squamous cell carcinoma of the tongue is reported with emphasis on an atypical finding of cervical lymph node metastasis visible on computed tomography. Multiple cervical lymph nodes revealed a high computed tomographic value of about 330 HU, lower than that of calcification. The lymph nodes revealed well-defined elliptical hyperechoic masses with an echogenic line and posterior shadow on ultrasonography. The appearance of a high density mass on computed tomography with a computed tomographic value lower than that of calcification may be a reliable finding of metastasis because it demonstrates the presence of marked keratinization produced by squamous cell carcinoma..
21. K Yoshiura, H Stamatakis, XQ Shi, U Welander, WD McDavid, J Kristoffersen, G Tronje, The perceptibility curve test applied to direct digital dental radiography, DENTOMAXILLOFACIAL RADIOLOGY, Vol.27, No.3, pp.131-135, 1998.05, Objective: To compare the effect of an additional scintillator layer on the psychophysical properties of a CCD detector for digital dental radiography.
Methods: Radiographs of a test object containing ten holes of increasing depth were obtained throughout the exposure range of two CCD detectors at 70 and 90 kVp. One was the original detector for the Sens-A-Ray system (Regam Medical Systems, Sundsvall, Sweden) and the other the same detector covered by a scintillator layer. Ten viewers evaluated the radiographs for the number of perceptible holes. From these data and the dose response functions for the two detectors, the minimum perceptible exposure difference was found. The reciprocal values of this parameter were plotted against the logarithm of exposure to create Perceptibility Curves (PCs).
Results: The four PCs had essentially the same shape and height. There was a shift to lower exposures in the PCs for the detector covered by a scintillator.
Conclusions: The two detectors have essentially the same psychophysical properties. Since the detector covered by a scintillator layer is more sensitive, it should be preferred for clinical practice since the dose to the patient is reduced..
22. M Shimizu, J Ussmuller, K Donath, K Yoshiura, S Ban, S Kanda, S Ozeki, M Shinohara, Sonographic analysis of recurrent parotitis in children - A comparative study with sialographic findings, ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY ORAL RADIOLOGY AND ENDODONTICS, Vol.86, No.5, pp.606-615, 1998.11, Objective. The sonographic features of recurrent parotitis in children were studied to clarify a relationship between sonographic and sialographic findings in this disease.
Study design. Twenty-one glands (7 on follow-up) were examined by 7.5 MHz ultrasonography and sialography. Echo intensity level, distribution of the internal echoes, and size of hypoechoic areas were compared with the size of punctate shadows on the sialograms. Twenty other histopathologic specimens were analyzed to investigate the entity of hypoechoic areas.
Results. Sonography showed hypoechoic, heterogeneous internal echoes, the level of which increased as the punctate shadows enlarged. Hypoechoic areas, all of which were larger than the sialographic punctate shadows, were observed in 62% of the glands. Histopathologic analysis suggests that these hypoechoic areas represent dilated peripheral ducts with lymphocytic infiltration. Sonography was likely to detect changes over time more sensitively than sialography.
Conclusions. Sonography should be performed as the test of first choice, both in the primary and follow-up stages, in cases of recurrent parotitis in children..
23. K Yoshiura, O Tabata, K Miwa, T Tanaka, M Shimizu, Y Higuchi, M Shinohara, S Kanda, Computed tomographic features of calcifying odontogenic cysts, DENTOMAXILLOFACIAL RADIOLOGY, Vol.27, No.1, pp.12-16, 1998.01, Objectives: To describe the CT appearances of 4 cases of the calcifying odontogenic cyst (COC) with particular reference to the effect of varying the window settings,
Methods: Conventional radiographs and CT scans of 4 calcifying odontogenic cysts were analyzed with respect to the presence of an impacted tooth, root resorption and calcification, In addition, increased attenuation by desquamated keratin was examined by varying the window settings on CT.
Results: All lesions were located in the maxilla and on conventional radiographs, had unilocular radiolucency with a well-defined margin, Calcifications and inclusion of an impacted tooth were seen in all cases. Root resorption was observed in two cases, but was not prominent, On CT, calcification was detected at the periphery of the lesion and/or around the impacted tooth in all cases. Varying the window setting revealed an increased attenuation area due to desquamated keratin.
Conclusions: Varying the window setting on CT is useful as a means of identifying both desquamated keratin and peripheral calcification in COC..
24. TK Goto, K Yoshiura, T Tanaka, S Kanda, S Ozeki, M Ohishi, Kobayashi, I, K Matsuo, A follow-up of rhabdomyosarcoma of the infratemporal fossa region in adults based on the magnetic resonance imaging findings - Case reports, ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY ORAL RADIOLOGY AND ENDODONTICS, Vol.86, No.5, pp.616-625, 1998.11, Two adult patients with rhabdomyosarcoma of the infratemporal fossa region were evaluated by computed tomography and magnetic resonance imaging both before and after treatment. Successful treatment accompanied by reduction of the tumor mass as a result of chemotherapy was demonstrated in one patient. In the other patient a subsequent increase in the tumor mass was documented. Information on not only the size but also the internal architecture of the tumor may be useful when tumor response to therapy is being investigated. Magnetic resonance imaging is recommended as a method for outcomes evaluation in adult rhabdomyosarcoma cases..
25. K Yoshiura, HC Stamatakis, U Welander, WD McDavid, XQ Shi, S Ban, T Kawazu, T Chikui, S Kanda, Prediction of Perceptibility Curves of direct digital intraoral radiographic systems, DENTOMAXILLOFACIAL RADIOLOGY, Vol.28, No.4, pp.224-231, 1999.07, 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..
26. K Yoshiura, HC Stamatakis, U Welander, WD McDavid, XQ Shi, S Ban, T Kawazu, M Tatsumi, S Kanda, Physical evaluation of a system for direct digital intra-oral radiography based on a charge-coupled device, DENTOMAXILLOFACIAL RADIOLOGY, Vol.28, No.5, pp.277-283, 1999.09, 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..
27. E Nakayama, K Yoshiura, K Yuasa, O Tabata, K Araki, S Kanda, S Ozeki, M Shinohara, Detection of bone invasion by gingival carcinoma of the mandible: a comparison of intraoral and panoramic radiography and computed tomography, DENTOMAXILLOFACIAL RADIOLOGY, Vol.28, No.6, pp.351-356, 1999.11, Objective: To assess the diagnostic accuracy of panoramic radiography (PR), panoramic radiography combined with intraoral radiography (PR+IR), and CT in detecting the supero-inferior extent of tumor invasion of the mandible by gingival carcinoma.
Method: PR, PR+IR, and CT images of the mandible in 37 patients with gingival carcinoma were evaluated by five oral radiologists for the supero-inferior extent of bone invasion using ROC analysis. The mean ROC curve area (A(z)) of each observer for the different imaging modalities was analysed by nonparametric two-way ANOVA. P < 0.05 was considered statistically significant.
Results: The mean A(z) for the detection of bone invasion were 0.88+/-0.03 for PR, 0.77+/-0.12 for PR+/-IR, and 0.87+/-0.03 for CT (P=0.0907). The mean A(z) for the detection of bone invasion beyond the alveolus was 0.89+/-0.07 for PR, 0.83+/-0.08 for PR+/-IR: and 0.83+/-0.06 for CT (P=0.5438). The mean A, for the detection of bone invasion beneath the mandibular canal were 0.94+/-0.04 for PR, 0.94+/-0.02 for PR+IR, and 0.91+/-0.04 for CT (P=0.2466). No statistically significant differences were observed in A, between PR, PR+IR, and CT.
Conclusion: We consider that PR+IR should be adopted as the initial imaging modality to determine the extent of supero-inferior invasion of the mandible in gingival carcinoma..
28. K Yoshiura, T Kawazu, T Chikui, M Tatsumi, K Tokumori, T Tanaka, S Kanda, Assessment of image quality in dental radiography, part 1 - Phantom validity, ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY ORAL RADIOLOGY AND ENDODONTICS, Vol.87, No.1, pp.115-122, 1999.01, Objective. The purpose of this study was to describe and validate an image-quality phantom to be used in dental radiography for comparison of film and digitally acquired images.
Study design. An aluminum block of 12 steps, with 7 holes in each step, was covered by acrylic blocks. This phantom was radiographed with Kodak Ultra-speed and Ektaspeed Plus films at 70, 65, and 60 kVp with the whole exposure range available. All together, 50 dental films were randomly sequenced and presented to 7 observers. The average number of perceptible holes from all steps was plotted against exposure for each tube voltage and film type, generating a modified perceptibility curve. The tentative optimum exposure revel was determined from perceptibility curves in each experimental condition and compared with that determined by means of the standard aluminum step-wedge and the preset time of the x-ray machine. The density range of this phantom at the optimum exposure was compared with that of clinical dental radiographs. Validity of the phantom was evaluated according to the optimum exposure level from the modified perceptibility curves and the overall density range. Finally, the average maximum numbers of perceptible holes at the tentative optimum exposure level were compared for each tube voltage and film type. The statistical test used was a 2-way factorial analysis of variance.
Results, The exposure at the perceptibility curve peak approximated that obtained by means of the standard aluminum step-wedge and the time preset by the manufacturer. The overall density range at the perceptibility curve peak covered the clinical density range for each tube voltage and film type. There were no statistically significant differences between firm types or among tube voltages.
Conclusions. The x-ray attenuation range for this phantom seemed to approximate clinical conditions. In addition, differences in image quality could be quantitatively evaluated by means of the number of the holes seen in the phantom..
29. K Yoshiura, T Kawazu, T Chikui, M Tatsumi, K Tokumori, T Tanaka, S Kanda, Assessment of image quality in dental radiography, part 2 - Optimum exposure conditions for detection of small mass changes in 6 intraoral radiography systems, ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY ORAL RADIOLOGY AND ENDODONTICS, Vol.87, No.1, pp.123-129, 1999.01, Objective, The purpose of this study was to compare 2 film systems and several digital intraoral systems with regard to visual image quality through use of a test phantom developed for this purpose.
Study design. The detectors used for digital imaging were as follows: Computed Dental Radiography (CDR), Digora, Dixel, and Sens-A-Ray without scintillator layer Two types of digital images were prepared for the observer performance test: one with original gray scales and another with contrast enhancement. Images with and without enhancement from the 4 systems were displayed to 7 observers. The change in the average number of perceptible holes was plotted against exposure, and modified perceptibility curves were created and compared with curves for the film systems. The exposure level at which the maximum number of holes was perceived was defined to be optimum. The optimum exposure levels were determined for each digital system and compared with that of the film systems. At the optimum exposure, the average maximum numbers of perceptible holes in each digital system with and without contrast enhancement were compared with the maximum numbers for the film systems. The minimum exposure levels were determined to be those at which the number of perceptible holes exceeded the number for film, and the possibility of exposure reduction was evaluated.
Results. All digital systems except the Digora system showed lower optimum exposures than E-speed film. In all digital images without enhancement, however, the maximum number of perceptible holes was significantly lower than that for the film systems at that exposure. With contrast enhancement, all digital systems except the Sens-A-Ray system showed visibility superior to that of the film systems. With the CDR, Digora, and Dixel systems, exposures could be further reduced by a considerable amount, with greater retention of information than was associated with film.
Conclusions. Our results strongly suggest that digital systems, if properly used, can exceed film systems in the detection of smalt mass changes..
30. HC Stamatakis, K Yoshiura, XQ Shi, U Welander, WD McDavid, A simplified method to obtain perceptibility curves for direct dental digital radiography, DENTOMAXILLOFACIAL RADIOLOGY, Vol.28, No.2, pp.112-115, 1999.03, Objectives: To derive and test a simplified method to construct Perceptibility Curves (PCs) for dental digital detectors.
Methods: Mathematical expressions were derived to make it possible to construct PCs from viewer data obtained at two exposures, one low and one high. PCs were constructed applying these expressions and compared with data previously obtained employing the conventional method.
Results: PCs constructed according to the simplified method agree extremely well with conventionally obtained data.
Conclusions: Reliable PCs may be constructed according to the simplified method..
31. M Shimizu, K Tokumori, M Saitoh, K Miwa, K Yoshiura, S Kanda, Sonographic analysis of rat submandibular glands in experimentally-induced sialadenitis, DENTOMAXILLOFACIAL RADIOLOGY, Vol.29, No.2, pp.90-96, 2000.03, Objectives: To correlate the sonographic features of experimentally-induced obstructive sialadenitis in rat submandibular glands with the histopathological changes.
Materials and methods: Changes in sonograms of ligated and non-ligated rat submandibular glands were compared with the wet weight and histopathology. Sonograms were obtained at 1, 2, 3, 4, 5, 7 and 21 days after duct ligation at 13 and 14 MHz for B-mode and for power Doppler mode respectively. Changes in gland size, echo intensity, distribution of internal echoes and vascularity were evaluated both qualitatively and quantitatively.
Results: Changes in size of the ligated glands were very similar to changes in wet weight. The ligated glands showed lower echo intensity than the non-ligated glands. The ligated glands showed higher echo intensity in the central portion at 4-7 days after duct ligation which resulted in heterogeneity of the glands. Vascularity of the ligated glands increased in the acute phase, and then decreased to the level of the non-ligated glands.
Conclusions: The three phases in the changes in ligated glands identifiable histopathologically can be differentiated by B-mode sonography. Power Doppler can differentiate the acute phase. Sonography therefore appears useful for the diagnosis of the degree of gland damage..
32. E Nakayama, K Yoshiura, K Yuasa, S Kanda, M Saitoh, W Kage, T Ikebe, S Ozeki, M Shinohara, A study of the association between the prognosis of carcinoma of the mandibular gingiva and the pattern of bone destruction on computed tomography, DENTOMAXILLOFACIAL RADIOLOGY, Vol.29, No.3, pp.163-169, 2000.05, Objective: To clarify whether the pattern of bone destruction seen on CT is more closely associated with the outcome of carcinoma of the mandibular gingiva than that derived from panoramic radiographs (PR).
Method: Axial bone window CT scans and PR of 62 patients with carcinoma of the mandibular gingiva were evaluated retrospectively by two oral radiologists for the pattern of bone destruction. Patterns were classified into the three types: erosive, invasive and mixed. The relationship between these patterns with each imaging modality and cumulative recurrence rate, cumulative metastasis rate and cumulative survival rate, calculated by the Kaplan-Meier method, were statistically analysed by the log rank test.
Results: The pattern of bone destruction derived from CT was closely associated with the cumulative metastasis rate (P<0.05), the cumulative recurrence rate and the cumulative survival rate. In contrast, the pattern of bone destruction based on the PR was not associated with the cumulative metastasis rate (P = 0.43), the cumulative recurrence rate (P = 0.44), or the cumulative survival rate (P = 0.5).
Conclusion: The prognosis of patients with carcinoma of the mandibular gingiva is more closely related to a classification derived from the pattern of bone destruction on CT rather than PR. However, the number of subjects investigated in this study was nor large enough to confirm our conclusions statistically. Further studies by other investigators are therefore needed..
33. TK Goto, K Yoshiura, E Nakayama, K Yuasa, O Tabata, T Nakano, T Kawazu, T Tanaka, K Miwa, M Shimizu, T Chikui, K Okamura, S Kanda, The combined use of US and MR imaging for the diagnosis of masses in the parotid region, ACTA RADIOLOGICA, Vol.42, No.1, pp.88-95, 2001.01, Purpose: To evaluate the usefulness of the combination of the two non-invasive modalities US and MR imaging to diagnose masses in the parotid region.
Material and Methods: The US and MR findings of 21 patients with parotid masses were analyzed retrospectively by two radiologists without any clinical or histopathological information. The specific points evaluated were location, shape, margin, internal architecture, and intensity level on both US and MR, posterior echo enhancement on US, and capsule-like lining of the tumor on MR.
Results: The findings concerning the shape and margin on US and MR were in fairly good agreement. Concerning the findings of the internal architecture. US could reveal the minute structures of the tumor while MR demonstrated differences in the signal intensities of histological tissue types of the various tumors. The posterior echo enhancement on US and the capsule-like lining on MR of the tumors were also useful for the diagnosis.
Conclusion: Our results suggest that the combination of US and MR is useful for examining soft tissue masses in the parotid region to make a more accurate diagnosis, and not just differentiate malignant lesions from those which are benign..
34. M Shimizu, K Tokumori, K Okamura, T Chikui, K Yoshiura, S Kanda, Possibility of sialographic sonography: A Doppler phantom study, ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY ORAL RADIOLOGY AND ENDODONTICS, 10.1067/moe.2001.113832, Vol.91, No.6, pp.719-727, 2001.06, Objectives. The purpose of this study was to develop a new diagnostic method that has the merits of both sialography and sonography
Study design. Saline solution and various contrast media (Urografin 76%; 100%, 90%, and 67% Lipiodol Ultra-Fluide; 5% and 1% barium sulfate; and Levovist) were injected into thin tubes at a rate of approximately 0.001 to 0.1 mL/s. The relationship between the Doppler signal intensity and the kind, concentration, and velocity of the fluid was analyzed.
Results. Levovist, 90% and 67% Lipiodol Ultra-Fluide, and the barium sulfate solutions produced Doppler signals. The mixture of Lipiodol Ultra-Fluide and saline solution produced high signals at any concentration, in contrast with the barium sulfate solutions. Signals could be observed at any speed, from the speed of normal sialography down to 0.001 mL/s, and there was a proportional relationship between signal intensity and velocity for all fluids producing signals.
Conclusion. The fact that we could obtain high signals with several fluids indicates potential clinical diagnostic usefulness of sialographic sonography..
35. K Yoshiura, U Welander, XQ Shi, G Li, T Kawazu, M Tatsumi, K Okamura, WD McDavid, S Kanda, Conventional and predicted Perceptibility Curves for contrast-enhanced direct digital intraoral radiographs, DENTOMAXILLOFACIAL RADIOLOGY, 10.1038/sj.dmfr.4600607, Vol.30, No.4, pp.219-225, 2001.07, Objectives: To construct Perceptibility Curves (PCs) for contrast-enhanced digital intraoral radiographs
Methods: Radiographs of a test object having holes of increasing depths were exposed using three digital systems, the CDR (Schick Technologies, Long Island, NY, USA), the Dixel (J Morita MFG, Kyoto, Japan) and the Sens-A-Ray (Regam Medical Systems, Sundsvall, Sweden). The radiographs were contrast-enhanced and PCs constructed in the conventional way using 10 observers. Predicted PCs were calculated and compared with observer data.
Results: The PCs showed that contrast enhancement is effective for the perception of small contrast details, especially in the low exposure range. Predicted PCs demonstrated excellent agreement with observer data.
Conclusions: Contrast enhancement should be advantageous in digital radiography. The effects of contrast enhancement on PCs may be predicted without previous knowledge of observer performance..
36. G Li, K Yoshiura, U Welander, P Sallstrom, WD McDavid, Visual linearization of the display of digital radiographs, DENTOMAXILLOFACIAL RADIOLOGY, 10.1038/sj/dmfr/4600663, Vol.31, No.2, pp.131-136, 2002.03, Objectives: To derive and test a method to linearize the visual response of the display of digital radiographs so that equal steps in gray levels will be perceived as equal steps in brightness.
Method: A mathematical analysis was performed and expressions for visual linearization were derived. Twenty-four test images were computer generated to confirm that visual linearization may be achieved. Each image had three groups of square areas of different size placed in three rows. The left and right squares in each row were given different gray levels to simulate various contrast levels. The middle squares were initially given the same gray level value as one of the outer squares. The images were examined by ten observers who could change the gray levels of the middle squares so that the step in brightness between the middle square and the outer squares become subjectively equal. The test was performed three times employing two different monitors.
Results: The experimental test confirmd that visual linearization could be achieved. Linear regression analyses gave determination coefficients of 0.9926 amd 0.9942 for monitors with values of 1.93 and 2.50, respectively. The mean data from the ten observers perfectly fitted those theoretically calculated.
Conclusion: Visual linearization of gray levels can be achieved but further clinical research is needed to determine if this improves diagnosis..
37. G Li, K Yoshiura, U Welander, XQ Shi, WD McDavid, Detection of approximal caries in digital radiographs before and after correction for attenuation and visual response. An in vitro study, DENTOMAXILLOFACIAL RADIOLOGY, 10.1038/sj/dmfr/4600675, Vol.31, No.2, pp.113-116, 2002.03, Objective: To evaluate if digital compensation for exponential attenuation and the characteristics or the human visual system improves the diagnosis of approximal caries from digital radiographs.
Material and methods: Forty premolar teeth were mounted in plaster blocks. Radiographs of the teeth were exposed with the Dixi digital intraoral system employing a Prostyle Intra dental X-ray unit (Planmeca Oy, Helsinki. Finland). Thirteen radiographs were then processed to compensate for the exponential attenuation and for the characteristic of the human visual system using equations presented in the paper. Ten observers were asked to diagnose approximal caries in all radiographs. ROC analyses were performed. The teeth were subsequently sectioned for histological validation of the lesions. The areas under ROC curves of original and processed radiographs were compared and analysed using Wilcoxon's signed-ranks test.
Results: There were significant diagnostic differences between the two types of radiographs (all lesions P=0.005, enamel P=0.028, and dentine P=0.050).
Conclusion: Digital radiographs processed to compensate for exponential attenuation and the characteristics of the human visual system significantly improves the diagnosis of approximal caries in vitro..
38. U Welander, K Yoshiura, G Li, P Sallstrom, WD McDavid, Correction for attenuation and visual response in digital radiography, DENTOMAXILLOFACIAL RADIOLOGY, 10.1038/sj/dmfr/4600673, Vol.31, No.2, pp.117-125, 2002.03, Objectives: To derive a method to correct for the exponential attenuation adding visual linearization for digital radiography and to perform an experimental test to study effects on observer performance.
Method: A theoretical analysis was performed and expressions were derived to correct radiographic data for the attenuation. An experiment was performed exposing an aluminum step wedge with holes of increasing depths behind each step plus soft tissue simulation. Seven original images were created with a digital intraoral X-ray sensor and a further 14 transformed images produced. Ten observers examined the images in a randomized order reporting the number of holes seen per wedge step. The results were analysed by One Way ANOVA.
Results: It was possible to correct for attenuation and the response of the human visual system to light intensities from a computer monitor, Perception was significantly improved in all recalculated radiographs that took both attenuation and the response of the eye into account (P-values ranged from <0.0001 to <0.0286).
Conclusions: The transforms may be useful for improved perception when viewing digital radiographs..
39. Akihiro Tayashima, Kazunori Yoshiura, Kenji Tokumori, Toshiyuki Kawazu, Shigenobu Kanda, Quantitative analysis of radiological changes in alveolar bone around connected osseo-integrated dental implants and natural abutment teeth, Oral Radiology, 10.1007/BF02493289, Vol.19, No.1, pp.28-37, 2003.06, Objective: To evaluate quantitatively the long-term changes in alveolar bone around tooth-implant connections using a digital subtraction technique. Study design: Eighteen cases where implants were embedded and connected to the mandibular molar teeth or to each other were analyzed. Digital subtraction images were obtained from baseline and follow-up digitized radiographs. These images were quantitatively analyzed by two methods, "area analysis" and "density analysis". Calcification and decalcification around the abutment teeth and implants were quantitatively evaluated. In two cases involving abutment teeth with a considerable loss of supporting periodontal tissues, the treatment process used was thoroughly evaluated to study how alveolar bone regeneration occurs in such patients. Results: No decalcification areas were detected in any of the cases. Calcification around abutment teeth, implants, or both was observed in 11 (92%) of 12 cases. In the remaining 6 cases, in which implants were connected to each other, calcification was observed around the implants in 4 cases (67%). In two cases where long-term quantitative analysis was possible, calcification started 4 years after placement of connected crowns. Conclusion: Connection of osseo-integrated implants to abutment teeth may be an effective treatment for patients suffering from periodontal disease..
40. Gang Li, Kazunori Yoshiura, Xie-Qi Shi, Ulf Welander, William D. McDavid, Physical properties of a system for direct acquisition of digital intraoral radiographs, Oral Radiology, 10.1007/BF02493288, Vol.19, No.1, pp.22-27, 2003.06, Objective: To determine technical properties for a direct digital intraoral radiographic system, F1 iOX (Fimet Oy, Monninkylä, Finland). Methods: A dose response function was calculated from seven radiographs exposed to a homogenous radiation field. The line spread function (LSF) and the modulation transfer function (MTF) were determined from a radiograph of a test object having a slit. Noise power spectra (NPSs) were determined at three exposures from radiographs exposed to a homogeneous radiation field. Noise equivalent quanta (NEQs) were calculated from NPSs and the MTF. Detective quantum efficiencies (DQEs) were determined from the NEQs and a representative value of the photon fluence. Signal-to-noise ratios (SNRs) were calculated from the NEQs and different signal contrasts. Results: The dose response function was linear and the system relatively sensitive. The maximum NPS was less than 10-5 mm2. NEQs indicate that the system captures a relatively high number of photons. At peaks of about 1 cycle/mm DQEs reached almost 35%. SNRs are relatively high. Conclusion: The technical properties found in this study indicate that the F1 iOX system is suitable for intraoral dental radiography..
41. K Yoshiura, U Welander, WD McDavid, G Li, XQ Shi, T Kawazu, M Tatsumi, T Matsuo, S Kanda, Perceptibility curves for the Digora system, DENTOMAXILLOFACIAL RADIOLOGY, 10.1259/dmfr/25806978, Vol.32, No.3, pp.191-197, 2003.05, Objectives: To construct perceptibility curves (PCs) for given calibration settings in order to define psychophysical properties of the Digora storage phosphor system and to evaluate the effects of automatic exposure correction (AEC) on the PCs.
Methods: The Digora system was calibrated at two exposures, 80 muC kg(-1) (high calibration) and 40 RC kg(-1) (low calibration). Since the grey levels displayed in the radiographs are adjusted by AEC, dose-response functions at high calibration were obtained using AEC on and off modes. The dose-response function at low calibration was obtained with AEC off. The PC at each experimental setting was calculated using known physical parameters of the system and the performance of the average observer used in a previous study. In addition, PCs were also constructed using transmitted radiation flux behind the test object calculated from the attenuation coefficient in order to study observer and system performance. PCs obtained under these conditions were compared.
Results: The PC using calculated transmitted radiation flux behind the test object showed a wide plateau at the peak owing to AEC, while the PC obtained by a modified approach showed a higher but narrower peak. There were no differences between the two PCs using AEC on and off modes when the PCs were constructed using a modified approach. There were no differences between the two PCs obtained at high and low calibration settings or between the three PCs obtained with AEC on except for the position along the exposure axis.
Conclusions: Psychophysical properties of the Digora system may be determined if we employ registered exposures from a dose-response function with AEC off under a given calibration setting. Under these circumstances the shape and height of the PCs will be unchanged irrespective of the AEC mode..
42. Kazunori Yoshiura, Ulf Welander, Gang Li, Xie-Qi Shi, William D. McDavid, Toshiyuki Kawazu, Masato Tatsumi, Kazutoshi Okamura, Shigenobu Kanda, Analysis of different approaches to constructing perceptibility curves, Oral Radiology, 10.1007/BF02493290, Vol.19, No.1, pp.38-48, 2003.06, Objectives: To construct and analyze perceptibility curves (PCs) according to two different approaches. Material and methods: A test object was used to determine the exposures and exposure differences between the total thickness of the test object and details consisting of holes of increasing depth. Two digital systems were employed to predict PCs according to the two different approaches. One approach defined exposures and exposure differences from dose-response functions, including secondary and scattered radiation. The other defined exposure and exposure differences as calculated transmitted radiation flux from the primary beam behind the test object, excluding secondary and scattered radiation. Integrals of the PCs and of the minimum perceptible gray-level differences as functions of background gray levels were calculated. The validity of the different types of PCs was analyzed. Another test object was used to predict observer performance for the two systems. Results: The integrals of PCs obtained according to the above first-mentioned approach and integrals of gray-level differences as functions of background gray level were equal. The same integrals using the second approach were different. The second approach, however, successfully predicted observer performance for the two systems. Conclusions: Only the first-mentioned approach gives PCs that are true representations of psychophysical properties. The second approach may, however, be employed to predict observer performance when different radiographic systems are employed..
43. K Yoshiura, U Welander, W McDavid, G Li, XQ Shi, E Nakayama, M Shimizu, K Kamura, S Kanda, Comparison of the psychophysical properties of various intraoral film and digital systems by means of the perceptibility curve test, DENTOMAXILLOFACIAL RADIOLOGY, 10.1259/dmfr/29102849, Vol.33, No.2, pp.98-102, 2004.03, Objectives: To compare psychophysical properties of two intraoral films and three digital systems using the perceptibility curve (PC) test.
Materials and methods: A test object was used to determine the exposures and exposure differences between the total thickness of the test object and details consisting of holes of increasing depth. The PCs for the two intraoral films, UltraSpeed and EktaSpeed Plus, were constructed employing exposure and exposure differences from dose response functions. Integrals of the PCs were calculated to obtain the psychophysical properties of the two films. Psychophysical properties of the two films were compared with those of the three digital systems published previously (CDR, Dixel and Digora).
Results: The PC for the EktaSpeed Plus showed a slightly higher peak than that for the UltraSpeed. Available exposure ranges were comparable. The PC for the EktaSpeed Plus was shifted to the left of the exposure axis indicating its higher sensitivity as compared with UltraSpeed. All three digital systems had narrower but higher peaks compared with the films. The integrals for the digital systems were considerably larger than those for the two film types.
Conclusions: All the three digital systems have superior psychophysical properties compared with the two tested films..
44. K Yoshiura, E Nakayama, M Shimizu, TK Goto, T Chikui, T Kawazu, K Okamura, Effects of the automatic exposure compensation on the proximal caries diagnosis, DENTOMAXILLOFACIAL RADIOLOGY, 10.1259/dmfr/88681265, Vol.34, No.3, pp.140-144, 2005.05, Objective: To elucidate the effect of automatic exposure compensation (AEC) on the diagnostic accuracy of proximal caries by comparing several digital intraoral imaging systems with a film.
Materials and methods: Twenty-seven extracted teeth served as proximal caries samples. Three digital radiographic systems; the Compuray, the Dixel, and the Sens-A-Ray without scintillator layer, and Kodak Ekta-speed Plus films were used as recording media. Radiographs of the teeth samples were obtained with each recording medium under seven to eight different exposures including the optimum level. Six oral radiologists evaluated the possibility of proximal caries with the five-grade-confidence-scale. On digital radiographs, image manipulations were allowed after the initial assessment. Receiver operating characteristic (ROC) curves were obtained at each exposure in each recording medium. The area under the ROC curve (Az) was used as the representative value of diagnostic accuracy. Diagnostic accuracy (DA) curves were obtained by plotting averaged A, values from all observers as a function of incident exposure in each system.
Results: The effect of exposure variation on the DA was slight in the film while it was significantly larger in the digital systems without AEC. Among digital systems, the effect of exposure variation was smaller in the system with AEC than those without AEC. There was no significant effect on the diagnostic accuracy even if digital image manipulation was employed.
Conclusion: AEC minimizes the decrease of DA due to inadequate exposures. Since it compensates for the narrow exposure range in the digital intraoral sensor systems, the system with AEC may be preferable for the clinical diagnostic tasks..
45. TK Goto, S Nishida, E Nakayama, Y Nakamura, S Sakai, H Yabuuchi, K Yoshiura, Correlation of mandibular deviation with temporomandibular joint MR dimensions, MR disk position, and clinical symptoms, ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY ORAL RADIOLOGY AND ENDODONTICS, 10.1016/j.tripleo.2005.05.063, Vol.100, No.6, pp.743-749, 2005.12, Objective. The objective of this study was to investigate the difference of the temporomandibular joint (TMJ) between deviated and nondeviated sides of the mandible in adult patients with mandibular deviation.
Study design. TMJ size, disk displacement, and clinical symptoms of 28 patients were examined clinically and by magnetic resonance imaging (MRI). Twelve age- and sex-matched control Subjects were also used to evaluate which side of the mandible in patients was similar to the control.
Results. The TMJ on the deviated side showed a smaller condyle and a higher incidence of disk displacement than the nondeviated side and those in the controls. However, the clinical symptoms showed no differences between the deviated and nondeviated sides, and no association with disk displacement.
Conclusions. Our results suggest that the deviated side was the abnormal side and may have some association with mandibular deviation. However, the clinical symptoms could not indicate those differences..
46. K Yoshiura, K Okamura, K Tokumori, E Nakayama, T Chikui, TK Goto, M Shimizu, T Kawazu, Correlation between diagnostic accuracy and perceptibility, DENTOMAXILLOFACIAL RADIOLOGY, 10.1259/dmfr/13550415, Vol.34, No.6, pp.350-352, 2005.11, Objectives: To correlate diagnostic accuracy for proximal caries with perceptibility of low contrast image details using regression analysis. The other purpose was to determine the attenuation range required for proximal caries diagnosis.
Methods: The results of the two types of observer performance tests described above were retrieved from previous studies. Recording media included in those studies were the Compuray and the Dixel, direct digital radiographic systems, and Ektaspeed Plus film. The average numbers of perceptibility of image details from five observers were calculated for each step and for every combination of contiguous steps of the aluminium test phantom from the perceptibility test. The average diagnostic accuracy for proximal caries from the same five observers was correlated with the total number of perceptible details from the phantom using regression analysis. Finally, attenuation range required for proximal caries diagnosis was calculated from the attenuation range of the phantom where the maximum correlation coefficient was obtained.
Results: Maximum correlation (r = 0.68) was obtained at the combination of five contiguous steps of the aluminium test phantom. Attenuation range required for proximal caries diagnosis corresponded to the 2 mm to 6 turn thickness of aluminium with acrylic block of 12 mm thickness.
Conclusions: There is a correlation between perceptibility of low contrast image details and diagnostic accuracy for proximal caries. There may be a possibility to simplify observer performance tests for proximal caries diagnosis by using the standardized phantom simulating its attenuation range..
47. Eiji Nakayama, Kazutoshi Okamura, Takeshi Mitsuyasu, Toshiyuki Kawazu, Norifumi Nakamura, Seiji Nakamura, Kazunori Yoshiura, A newly developed interventional sialendoscope for a completely nonsurgical sialolithectomy using intracorpereal electrohydraulic lithotripsy, JOURNAL OF ORAL AND MAXILLOFACIAL SURGERY, 10.1016/j.jams.2005.11.087, Vol.65, No.7, pp.1402-1405, 2007.07.
48. Eiji Nakayama, Kazutoshi Okamura, Takeshi Mitsuyasu, Toshiyuki Kawazu, Norifumi Nakamura, Seiji Nakamura, Kazunori Yoshiura, A Newly Developed Interventional Sialendoscope for a Completely Nonsurgical Sialolithectomy Using Intracorporeal Electrohydraulic Lithotripsy, Journal of Oral and Maxillofacial Surgery, 10.1016/j.joms.2005.11.087, Vol.65, No.7, pp.1402-1405, 2007.07.
49. 顎顔面領域における節外性悪性リンパ腫の臨床的検討.
50. 医科用CTにおける金属アーチファクト低減効果の定量的評価.
51. Toru Chikui, Makoto Obara, ArjanW. Simonetti, Masahiro Ohga, Shoichi Koga, Shintaro Kawano, Yoshio Matsuo, Takeshi Kamintani, Tomoko Shiraishi, Erina Kitamoto, Katsumasa Nakamura, Kazunori Yoshiura, The principal of dynamic contrast enhanced MRI, the method of pharmacokinetic analysis, and its application in the head and neck region, 2012.10.
52. K Yoshiura, Image quality assessment of digital intraoral radiography – perception to caries diagnosis, 2012.02.
53. Kabashima H, Mizobe K, Nakamuta H, Fujiwara H, Okamura K, Unemori M, Akamine A, Yoshiura K, Maeda K, The usefulness of three-dimensional imaging in the diagnosis and treatment of clinically ambiguous gingival swelling, J Oral Science, 53(2): 257-261, 2011.08.