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

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


Papers
1. Toru Chikui, Kenji Tokumori, Wannakamon Panyarak, Osamu Togao, Yasuo Yamashita, Shintaro Kawano, Takeshi Kamitani, Kazunori Yoshiura, The application of a gamma distribution model to diffusion-weighted images of the orofacial region., Dento maxillo facial radiology, 10.1259/dmfr.20200252, 50, 2, 20200252-20200252, 2021.02, OBJECTIVES: This study evaluated the correlation among the diffusion-derived parameters obtained by monoexponential (ME), intravoxel incoherent motion (IVIM) and γ distribution (GD) models and compared these parameters among representative orofacial tumours. METHODS: Ninety-two patients who underwent 1.5 T MRI including diffusion-weighted imaging were included. The shape parameter (κ), scale parameter (θ), ratio of the intracellular diffusion (ƒ1), extracellular diffusion (ƒ2) and perfusion (ƒ3) were obtained by the GD model; the true diffusion coefficient (D) and perfusion fraction (f) were obtained by the IVIM model; and the apparent diffusion coefficient (ADC) was obtained by the ME model. RESULTS: ƒ1 had a strongly negative correlation with the ADC (ρ = -0.993) and D (ρ = -0.926). A strong positive correlation between f and ƒ3 (ρ = 0.709) was found. Malignant lymphoma (ML) had the highest ƒ1, followed by squamous cell carcinoma (SCC), malignant salivary gland tumours, pleomorphic adenoma (Pleo) and angioma. Both the IVIM and GD models suggested the highest perfusion in angioma and the lowest perfusion in ML. The GD model demonstrated a high extracellular component in Pleo and revealed that the T4a+T4b SCC group had a lower ƒ2 than the T2+T3 SCC group, and poor to moderately differentiated SCC had a higher ƒ1 than highly differentiated SCC. CONCLUSIONS: Given the correlation among the diffusion-derived parameters, the GD model might be a good alternative to the IVIM model. Furthermore, the GD model's parameters were useful for characterizing the pathological structure..
2. Taku Kuramoto, Shinya Takarabe, Kenshi Shiotsuki, Yusuke Shibayama, Hiroshi Hamasaki, Hiroshi Akamine, Kazutoshi Okamura, Toru Chikui, Toyoyuki Kato, Kazunori Yoshiura, X-ray dose reduction using additional copper filtration for dental cone beam CT., Physica medica : PM : an international journal devoted to the applications of physics to medicine and biology : official journal of the Italian Association of Biomedical Physics (AIFB), 10.1016/j.ejmp.2020.11.022, 81, 302-307, 2021.01, This study aims to quantitatively evaluate the effect of additional copper-filters (Cu-filters) on the radiation dose and contrast-to-noise ratio (CNR) in a dental cone beam computed tomography (CBCT). The Cu-filter thickness and tube voltage of the CBCT unit were varied in the range of 0.00-0.20 mm and 70-90 kV, respectively. The CBCT images of a phantom with homogeneous materials of aluminum, air, and bone equivalent material (BEM) were acquired. The CNRs were calculated from the voxel values of each homogeneous material. The CTDIvol was measured using standard polymethyl methacrylate CTDI test objects. We evaluated and analyzed the effects of tube current and various radiation qualities on the CNRs and CTDIvol. We observed a tendency for higher CNR at increasing tube voltage and tube current in all the homogeneous materials. On the other hand, the CNR reduced at increasing Cu-filter thickness. The tube voltage of 90 kV showed a clear advantage in the tube current-CNR curves in all the homogeneous materials. The CTDIvol increased as the tube voltage and tube current increased and decreased with the increase in the Cu-filter thickness. When the CNR was fixed at 9.23 of BEM at an exposure setting of 90 kV/5 mA without a Cu-filter, the CTDIvol at 90 kV with Cu-filters was 8.7% lower compared with that at 90 kV without a Cu-filter. The results from this study demonstrate the potential of adding a Cu-filter for patient dose reduction while ensuring the image quality..
3. Kazutoshi Okamura, Kazunori Yoshiura, The missing link in image quality assessment in digital dental radiography., Oral radiology, 10.1007/s11282-019-00396-z, 36, 4, 313-319, 2020.10, Digital radiography is gaining popularity among general dental practitioners. It includes digital intraoral radiography, digital panoramic radiography, digital cephalography, and cone-beam computed tomography. In this study, we focused on the methods to assess image quality of these techniques, except for digital cephalography, in the light of historical issues. We stressed on the importance of the development of a standardized phantom and quantitative analysis of diagnostic image quality using it, especially in the aspect of psychophysical properties of these digital systems. There is no missing link in the image quality assessment in digital intraoral radiography and cone-beam computed tomography in dental use. However, there are missing links between physical and diagnostic image qualities in panoramic radiography. The development of a semi-standardized phantom and the corresponding quantitative analysis method for image quality may be required in digital panoramic radiography. Quantitative image quality assessment using a standardized phantom will also be promising in the future artificial intelligence era..
4. Taku Kuramoto, Shinya Takarabe, Kazutoshi Okamura, Kenshi Shiotsuki, Yusuke Shibayama, Hiroki Tsuru, Hiroshi Akamine, Masato Tatsumi, Toyoyuki Kato, Junji Morishita, Kazunori Yoshiura, Effect of differences in pixel size on image characteristics of digital intraoral radiographic systems: a physical and visual evaluation., Dento maxillo facial radiology, 10.1259/dmfr.20190378, 49, 6, 20190378-20190378, 2020.09, OBJECTIVES: To quantify and validate the effect of pixel size on a digital intraoral radiographic system according to International Electrotechnical Commission standards through physical and visual evaluations. METHODS: The digital intraoral radiographic system used was the photostimulable phosphor imaging plate and scanner system. The system had three image capture modes: high-speed (HS), high-resolution (HR), and super high-resolution (SHR) with different pixels. The physical characteristics of the system were evaluated using presampled modulation transfer function (MTF) and the normalized noise power spectrum (NNPS). An aluminum (Al) step phantom with different depths of holes was used to acquire images under various exposure conditions. The average number of perceptible holes from all steps was plotted against each exposure dose. The results were compared to analyze the effects of pixel size on image quality of intraoral radiographs. RESULTS: The MTF was slightly higher with SHR than with HR and HS. The NNPS with SHR showed about a 40% decrease in magnitude compared to HS. The total number of perceptible holes in the Al step phantom was higher with SHR than with HS and HR in all exposure conditions. CONCLUSIONS: The MTF and NNPS obtained with different pixel size could be quantified by physical evaluation, and the differences were visually validated with Al step phantom. The SHR mode has the potential to decrease the radiation dose without compromising the image quality..
5. Yuki Sakai, Kazutoshi Okamura, Erina Kitamoto, Yukiko N Kami, Takashi Shirasaka, Ryoji Mikayama, Masato Tatsumi, Masatoshi Kondo, Toyoyuki Kato, Kazunori Yoshiura, Improved scan method for dental imaging using multidetector computed tomography: a phantom study., Dento maxillo facial radiology, 10.1259/dmfr.20190462, 49, 6, 20190462-20190462, 2020.09, OBJECTIVES: This study aimed to propose an improved scan method to shorten irradiation time and reduce radiation exposure. METHODS: The maxilla of a human head CT phantom and a Catphan phantom were used for qualitative and quantitative assessment, respectively. The phantoms were scanned by a 160-row multidetector CT scanner using volumetric and helical scanning. In volumetric scanning, the tube current varied from 120 to 60 to 30 to 20 mA with a tube voltage of 120 kV. Images were reconstructed with a bone kernel using iterative reconstruction (IR) and filtered back projection. As a reference protocol, helical scanning was performed using our clinical setting with 120 kV. Two dental radiologists independently graded the quality of dental images using a 4-point scale (4, superior to reference; 1, unacceptable). For the quantitative assessment, we assessed the system performance from each scan. RESULTS: There was no significant difference between the image quality of volumetric scanning using the 60 mA protocol reconstructed with IR and that of the reference (3.08 and 3.00, p = 0.3388). The system performance values at 1.0 cycles/mm of volumetric scanning and 60 mA protocol reconstructed with IR and reference were 0.0038 and 0.0041, respectively. The effective dose of volumetric scanning using the 60 mA protocol was 51.8 µSv, which is a 64.2% reduction to that of the reference. CONCLUSIONS: We proposed an improved scan method resulting in a 64.2% reduction of radiation dose with one-fourth of irradiation time by combining volumetric scanning and IR technique in multidetector CT..
6. Kami Y, Chikui T, Togao O, Ooga M, Yoshiura K., Comparison of image quality of head and neck lesions between 3D gradient echo sequences with compressed sensing and the multi-slice spin echo sequence, Acta Radiologica Open, 10.1177/2058460120956644, 9, 1-8, 9: 1-8, 2020.08.
7. Panyarak W, Chikui T, Tokumori K, Yamashita Y, Kamitani T, Togao O, Yoshiura K., Utility of a diffusion kurtosis model in the differential diagnosis of orofacial tumours., Clinical Radiology, 2020.01.
8. Yoshitaka Kise, Mayumi Shimizu, Haruka Ikeda, Takeshi Fujii, Chiaki Kuwada, Masako Nishiyama, Takuma Funakoshi, Yoshiko Ariji, Hiroshi Fujita, Akitoshi Katsumata, Kazunori Yoshiura, Eiichiro Ariji, Usefulness of a deep learning system for diagnosing sjögren's syndrome using ultrasonography images, Dentomaxillofacial Radiology, 10.1259/dmfr.20190348, 49, 3, 2020.01, Objectives: We evaluated the diagnostic performance of a deep learning system for the detection of Sjögren's syndrome (SjS) in ultrasonography (US) images, and compared it with the performance of inexperienced radiologists. Methods: 100 patients with a confirmed diagnosis of SjS according to both the Japanese criteria and American-European Consensus Group criteria and 100 non-SjS patients that had a dry mouth and suspected SjS but were definitively diagnosed as non-SjS were enrolled in this study. All the patients underwent US scans of both the parotid glands (PG) and submandibular glands (SMG). The training group consisted of 80 SjS patients and 80 non-SjS patients, whereas the test group consisted of 20 SjS patients and 20 non-SjS patients for deep learning analysis. The performance of the deep learning system for diagnosing SjS from the US images was compared with the diagnoses made by three inexperienced radiologists. Results: The accuracy, sensitivity and specificity of the deep learning system for the PG were 89.5, 90.0 and 89.0%, respectively, and those for the inexperienced radiologists were 76.7, 67.0 and 86.3%, respectively. The deep learning system results for the SMG were 84.0, 81.0 and 87.0%, respectively, and those for the inexperienced radiologists were 72.0, 78.0 and 66.0%, respectively. The AUC for the inexperienced radiologists was significantly different from that of the deep learning system. conclusions: The deep learning system had a high diagnostic ability for SjS. This suggests that deep learning could be used for diagnostic support when interpreting US images..
9. Panyarak W, Chikui T, Yamashita Y, Kamitani T, Yoshiura K., Image Quality and ADC Assessment in Turbo Spin-Echo and Echo-Planar Diffusion-Weighted MR Imaging of Tumors of the Head and Neck., Academic Radiology, 26, 10, e305-e316, 2019.10.
10. Determination of optimum exposure parameters for dentoalveolar structures of the jaws using the CB MercuRay system with cluster signal-to-noise analysis..
11. Chikui T, Yamashita Y, Kise Y, Saito T, Okamura K, Yoshiura K, Estimation of proton density fat fraction of the salivary gland, Br J Radiol., 10.1259/bjr.20170671, 91, 1085, 2018.05.
12. Warangkana Weerawanich, Mayumi Shimizu, Yohei Takeshita, Kazutoshi Okamura, Shoko Yoshida, Gainer R. Jasa, Kazunori Yoshiura, Evaluation of cone-beam computed tomography diagnostic image quality using cluster signal-to-noise analysis, Oral Radiology, 10.1007/s11282-018-0325-0, 1-9, 2018.03, Objectives: (1) We sought to assess correlation among four representative parameters from a cluster signal-to-noise curve (true-positive rate [TPR] corresponding to background noise, accuracy corresponding to background noise, maximum TPR, and maximum accuracy) and the diagnostic accuracy of the identification of the mandibular canal using data from observers in a previous study, under the same exposure conditions. (2) We sought to clarify the relationship between the hole depths of a phantom and diagnostic accuracy. Methods: CBCT images of a Teflon plate phantom with holes of decreasing depths from 0.7 to 0.1 mm were analyzed using the FindFoci plugin of ImageJ. Subsequently, we constructed cluster signal-to-noise curves by plotting TPRs against false-positive rates. The four parameters were assessed by comparing with the diagnostic accuracy calculated from the observers. To analyze image contrast ranges related to detection of mandibular canals, we determined five ranges of hole depths, to represent different contrast ranges—0.1–0.7, 0.1–0.5, 0.2–0.6, 0.2–0.7 and 0.3–0.7 mm—and compared them with observers’ diagnostic accuracy. Results: Among the four representative parameters, accuracy corresponding to background noise had the highest correlation with the observers’ diagnostic accuracy. Hole depths of 0.3–0.7 and 0.1–0.7 mm had the highest correlation with observers’ diagnostic accuracy in mandibles with distinct and indistinct mandibular canals, respectively. Conclusions: The accuracy corresponding to background noise obtained from the cluster signal-to-noise curve can be used to evaluate the effects of exposure conditions on diagnostic accuracy..
13. Warangkana Weerawanich, Mayumi Shimizu, Yohei Takeshita, Kazutoshi Okamura, Shoko Yoshida, Gainer R. Jasa, Kazunori Yoshiura, Evaluation of cone-beam computed tomography diagnostic image quality using cluster signal-to-noise analysis, Oral Radiology, 10.1007/s11282-018-0325-0, 35, 59-67, 2018.03.
14. Warangkana Weerawanich, Mayumi Shimizu, Yohei Takeshita, Kazutoshi Okamura, Shoko Yoshida, Gainer R. Jasa, Kazunori Yoshiura, Evaluation of cone-beam computed tomography diagnostic image quality using cluster signal-to-noise analysis, Oral Radiology, 10.1007/s11282-018-0325-0, 35, 1, 1-9, 2018.03, Objectives: (1) We sought to assess correlation among four representative parameters from a cluster signal-to-noise curve (true-positive rate [TPR] corresponding to background noise, accuracy corresponding to background noise, maximum TPR, and maximum accuracy) and the diagnostic accuracy of the identification of the mandibular canal using data from observers in a previous study, under the same exposure conditions. (2) We sought to clarify the relationship between the hole depths of a phantom and diagnostic accuracy. Methods: CBCT images of a Teflon plate phantom with holes of decreasing depths from 0.7 to 0.1 mm were analyzed using the FindFoci plugin of ImageJ. Subsequently, we constructed cluster signal-to-noise curves by plotting TPRs against false-positive rates. The four parameters were assessed by comparing with the diagnostic accuracy calculated from the observers. To analyze image contrast ranges related to detection of mandibular canals, we determined five ranges of hole depths, to represent different contrast ranges—0.1–0.7, 0.1–0.5, 0.2–0.6, 0.2–0.7 and 0.3–0.7 mm—and compared them with observers’ diagnostic accuracy. Results: Among the four representative parameters, accuracy corresponding to background noise had the highest correlation with the observers’ diagnostic accuracy. Hole depths of 0.3–0.7 and 0.1–0.7 mm had the highest correlation with observers’ diagnostic accuracy in mandibles with distinct and indistinct mandibular canals, respectively. Conclusions: The accuracy corresponding to background noise obtained from the cluster signal-to-noise curve can be used to evaluate the effects of exposure conditions on diagnostic accuracy..
15. Warangkana Weerawanich, Mayumi Shimizu, Yohei Takeshita, Kazutoshi Okamura, Shoko Yoshida, Kazunori Yoshiura, Cluster signal-to-noise analysis for evaluation of the information content in an image, Dentomaxillofacial Radiology, 10.1259/dmfr.20170147, 47, 1, 2018.01, Objectives: (1) To develop an observer-free method of analysing image quality related to the observer performance in the detection task and (2) to analyse observer behaviour patterns in the detection of small mass changes in cone-beam CT images. Methods: 13 observers detected holes in a Teflon phantom in cone-beam CT images. Using the same images, we developed a new method, cluster signal-to-noise analysis, to detect the holes by applying various cut-off values using ImageJ and reconstructing cluster signal-tonoise curves. We then evaluated the correlation between cluster signal-to-noise analysis and the observer performance test. We measured the background noise in each image to evaluate the relationship with false positive rates (FPRs) of the observers. Correlations between mean FPRs and intra- and interobserver variations were also evaluated. Moreover, we calculated true positive rates (TPRs) and accuracies from background noise and evaluated their correlations with TPRs from observers. Results: Cluster signal-to-noise curves were derived in cluster signal-to-noise analysis. They yield the detection of signals (true holes) related to noise (false holes). This method correlated highly with the observer performance test (R2 = 0.9296). In noisy images, increasing background noise resulted in higher FPRs and larger intra- and interobserver variations. TPRs and accuracies calculated from background noise had high correlation with actual TPRs from observers; R2 was 0.9244 and 0.9338, respectively. Conclusions: Cluster signal-to-noise analysis can simulate the detection performance of observers and thus replace the observer performance test in the evaluation of image quality. Erroneous decision-making increased with increasing background noise..
16. Toru Chikui, Yasuo Yamashita, Yoshitaka Kise, Tomonori Saito, Kazutoshi Okamura, Kazunori Yoshiura, Estimation of proton density fat fraction of the salivary gland, British Journal of Radiology, 10.1259/bjr.20170671, 91, 1085, 2018.01, Objective: Our first objective was to prove the validity of the six-point Dixon method for estimating the proton density fat fraction (PDFF) of the salivary gland. The second objective was to estimate the salivary gland PDFF using Dixon method to evaluate the pathological conditions. Methods: At first, 12 volunteers underwent two types of sequences: single-voxel magnetic resonance spectroscopy and the Dixon method and the PDFFs obtained by the two methods were compared. Next, a total of 67 individuals [normal, n = 46; Sjögren's syndrome (SS), n = 11; and IgG4-related dacryoadenitis and sialadenitis (IgG4-DS), n = 4, parotitis, n = 6] were enrolled to estimate the parotid gland (PG) and submandibular gland (SMG) PDFF using the Dixon method. Results: This volunteer study demonstrated excellent correlation between two methods (R2 = 0.964, slope = 1.05). In the normal group, the PG-PDFF was correlated with the weight and body mass index (BMI) (ρ = 0.38, p = 0.0085; and ρ = 0.63, p < 0.0001). The SMG-PDFF was also correlated with the weight, BMI, and serum triglyceride (ρ = 0.37, p = 0.0067; ρ = 0.42, p = 0.0022; and ρ = 0.35, p = 0.024). The PG-PDFF of the SS group (48.2 ± 15.1%) was higher than that of any other groups; however, no significant difference was found due to the wide overlap. The SS group (39.0 ± 26.14%) also had significantly higher SMG-PDFF than the normal group (8.9 ± 5.4%), p < 0.0001) and IgG4-DS group (3.8 ± 2.3%), p = 0.020). Conclusion: The Dixon method is a feasible method for estimating the PDFF and demonstrates fat accumulation in SMG in the SS group. Advances in knowledge: The PDFF obtained by the Dixon method is helpful for understanding the salivary gland pathological condition..
17. Warangkana Weerawanich, Mayumi Shimizu, Yohei Takeshita, Kazutoshi Okamura, Shoko Yoshida, Gainer R. Jasa, Kazunori Yoshiura, Determination of optimum exposure parameters for dentoalveolar structures of the jaws using the CB MercuRay system with cluster signal-to-noise analysis, Oral Radiology, 10.1007/s11282-018-0348-6, 2018.01, Objective: To determine the optimum cone beam computed tomography exposure parameters for specific diagnostic tasks. Methods: A Teflon phantom attached to a half-mandible in a large container was scanned in dental (D), implant (I), and panoramic (P) modes. An identical phantom in a small container was scanned in D mode. Both were scanned at 60, 80, 100, and 120 kV. We evaluated the image quality of five anatomical structures [dentinoenamel junction (1), lamina dura and periodontal ligament space (2), trabecular pattern (3), cortex–spongy bone junction (4), and pulp chamber and root canal (5)] and analyzed the diagnostic image quality with cluster signal-to-noise analysis. We then evaluated correlations between the two image qualities and calculated the threshold of acceptable diagnostic image quality. Optimum exposure parameters were determined from images with acceptable diagnostic image quality. Results: For the small container, the optimum exposure parameters were D mode, 80 kV for (1), (3), and (4) and D mode, 100 kV for (5). For the large container, they were D mode, 120 kV for (1), (3), and (5) and D mode, 100 kV for (4). I mode, 120 kV reached the acceptable level for (4). No images reached the acceptable level for (2). Conclusions: No optimum exposure parameters were identified for the evaluation of the lamina dura and periodontal ligament space. D mode was sufficient for the other structures; however, the tube voltage required for each structure differed. Smaller patients required lower tube voltage. I mode, 120 kV may be used for larger lesions..
18. Tatsushi Tokuyasu, Tsubasa Maruyama, Takahiro Yamamoto, Kazuhiko Toshimitsu, Kazutoshi Okamura, Kazunori Yoshiura, Development of virtual patient model for maxillofacial palpation training using Meshless method, IEEJ Transactions on Electronics, Information and Systems, 10.1541/ieejeiss.138.899, 138, 7, 899-905, 2018.01, For dental therapy, a dentist often touches a patient face in order to identify the causes of pains such as a tumor and/or cancer. Although the importance of maxillofacial palpation has been recognized, practical training with a dental patient has not been conducted for taking care of the safety of the patient in dental school. The training of therapeutic planning with an advising doctor would be effective to enhance the quality of dental therapy. Then, this study has developed a virtual training system for maxillofacial palpation which can be utilized in dental education. In this study, we first took a multi-slice CT data from a human head mannequin in order to obtain the shape data of a virtual patient model. This study adopted Meshless Method (MLM) to construct the dynamic model of the virtual patient model. In the experimental results using a haptic interface, PHANToM Omni, the parameters of MLM influenced the surface deformation of the virtual patient model. This paper finally discussed the availability of MLM for the virtual training system and clarified the current issues that should be solved to utilize the system in dental education..
19. Wannakamon Panyarak, Toru Chikui, Yasuo Yamashita, Takeshi Kamitani, Kazunori Yoshiura, Image Quality and ADC Assessment in Turbo Spin-Echo and Echo-Planar Diffusion-Weighted MR Imaging of Tumors of the Head and Neck, Academic Radiology, 10.1016/j.acra.2018.11.016, 2018.01, Rationale and Objectives: We aimed to compare the distortion ratio (DR), signal-to-noise ratio (SNR), and contrast-to-noise ratio (CNR) between turbo spin-echo (TSE)-diffusion-weighted imaging (DWI) and echo-planar imaging (EPI)-DWI of the orofacial region and prove the usefulness of TSE-DWI for the differential diagnosis of orofacial lesions. Materials and methods: The DR, SNR, and CNR of both sequences were compared in 42 cases. Then, the apparent diffusion coefficient (ADC) of various orofacial lesions obtained by TSE-DWI was investigated in 143 lesions. Results: In the first study, 38 of 42 cases were analyzed. TSE-DWI showed a significantly lower DR (p < 0.05) and higher SNR and CNR than EPI-DWI (p < 0.05), indicating the superiority of TSE-DWI. In the second study, 114 cases (79.3%) were successfully analyzed. When lesions were divided into cysts, benign tumors, squamous cell carcinoma, malignant lymphoma, and other malignant tumors (OT), significant differences were observed in all pairs of lesions (p < 0.05) except squamous cell carcinoma and OT (p = 0.877). The area under the curve for distinguishing benign from malignant tumors was 0.80 with a cutoff ADC of 1.29 × 10-3 mm²/s. Conclusion: TSE-DWI produced better quality images than EPI-DWI. TSE-DWI yields the high possibility of obtaining ADC in the orofacial region, and this value was considered useful for the differential diagnosis of orofacial lesions..
20. Yohei Takeshita, Mayumi Shimizu, Gainer R. Jasa, Warangkana Weerawanich, Kazutoshi Okamura, Shoko Yoshida, Kenji Tokumori, Junichi Asaumi, Kazunori Yoshiura, Prediction of detectability of the mandibular canal by quantitative image quality evaluation using cone beam ct, Dentomaxillofacial Radiology, 10.1259/dmfr.20170369, 47, 4, 2018.01, Objectives: To compare the results of a new quantitative image quality evaluation method that requires no observers with the results of receiver operating characteristic (ROC) analysis in detecting the mandibular canal (MC) in cone beam CT (CBCT) images. Methods: A Teflon (polytetrafluoroethylene) plate phantom with holes of different depths was scanned with two CBCT systems. One CBCT system was equipped with an image intensifier (Experiment 1), and the other was equipped with a flat panel detector (Experiment 2). Holes that were above the threshold gray value (ΔG), calculated using just-noticeable difference (JND), were extracted. The number of extracted holes was used as the index of the image quality, and was compared with the Az values calculated by ROC analysis to detect the MC. Results: The number of extracted holes reflected the influence of different scanning conditions, and showed a strong correlation with the Az values calculated by ROC analysis. Indices of the number of extracted holes corresponding to high Az values for detecting the MC were obtained in both experiments. conclusions: Our image quality evaluation method applying JND to images of a standardized phantom is a quantitative method that could be useful for evaluating the detectability of the MC in CBCT images..
21. Hiroko Furuhashi, Toru Chikui, Daisuke Inadomi, Tomoko Shiraishi, 吉浦 一紀, Fundamental tongue motions for trumpet playing: A study using cine Magnetic Resonance Imaging (Cine MRI), Medical Problems of Performing Artists, 10.21091/mppa.2017.4038, 32, 4, 201-208, 32(4):201-208, 2017.12.
22. Yoshitaka Kise, Toru Chikui, Yamashita Y, Kobayashi K, 吉浦 一紀, Clinical usefulness of the mDIXON Quant the method for estimation of the salivary gland fat fraction: comparison with MR spectroscopy, Br J Radiol, 10.1259/bjr.20160704, 90, 2017.07.
23. Sitti Fadhillah Oemar Mattalitti, Toshiyuki Kawazu, Shintaro Kawano, Tatsuya Ikari, Hiroko Wada, Kazunori Yoshiura, Estimation of prognosis of tongue cancer using tumor depth and margin shape obtained from ultrasonography, ORAL RADIOLOGY, 10.1007/s11282-016-0251-y, 33, 2, 101-107, 2017.05, To evaluate the feasibility of using ultrasound-obtained tumor depth (TD) and margin shape (MS) to predict the prognosis of tongue cancer.
Fifty-two Japanese patients with tongue cancer who underwent ultrasound examination between 2007 and 2012 were retrospectively evaluated. TD was measured at the deepest portion of the tumor. MS was classified as "pressure," "wedge-shaped," or "permeated." Prognosis was assessed by local recurrence, lymph node metastasis, and overall survival rate. We classified the patients into a good prognosis group and poor prognosis group. Relationships among TD, MS, and patient prognosis were evaluated using Spearman rank correlation. A regression formula to predict prognosis using TD and MS was derived.
The correlation between TD and MS was significant (Spearman rank correlation rho = 0.552, p < 0.01). Using a structure matrix, we identified the contribution of both predictors from an ultrasound image. The contribution of TD was 0.796, while that of MS was better at 0.906. The prognosis could be predicted using the following regression formula: , where D prognosis (risk probability), x = TD (mm), and y = MS (grade). The average value for good risk probability was -0.254 (standard deviation, 0.962), while that for poor risk probability was 0.566 (standard deviation, 1.08) (p < 0.05). The cut-off value for classifying cases was -0.00169. Using the formula above, 73.1 % of patients in the poor prognosis group were correctly classified.
MS and TD are useful predictors of tongue cancer prognosis..
24. Gainer R Jasa, Mayumi Shimizu, Kazutoshi Okamura, 徳森謙二, Takeshita Y, Weerawanich W, 吉浦 一紀, Effects of exposure parameters and slice thickness on detecting clear and unclear mandibular canals using cone beam CT, DENTOMAXILLOFACIAL RADIOLOGY, 10.1259/dmfr.20160315, 46, 4, 2017.05.
25. Yohei Takeshita, Mayumi Shimizu, Kazutoshi Okamura, Shoko Yoshida, Warangkana Weerawanich, Kenji Tokumori, Gainer R. Jasa, Kazunori Yoshiura, A new method to evaluate image quality of CBCT images quantitatively without observers, Dentomaxillofacial Radiology, 10.1259/dmfr.20160331, 46, 3, 2017.03, Objectives: To develop an observer-free method for quantitatively evaluating the image quality of CBCT images by applying just-noticeable difference (JND). Methods: We used two test objects: (1) a Teflon (polytetrafluoroethylene) plate phantom attached to a dry human mandible; and (2) a block phantom consisting of a Teflon step phantom and an aluminium step phantom. These phantoms had holes with different depths. They were immersed in water and scanned with a CB MercuRay (Hitachi Medical Corporation, Tokyo, Japan) at tube voltages of 120 kV, 100 kV, 80 kV and 60 kV. Superimposed images of the phantoms with holes were used for evaluation. The number of detectable holes was used as an index of image quality. In detecting holes quantitatively, the threshold grey value (DG), which differentiated holes from the background, was calculated using a specific threshold (the JND), and we extracted the holes with grey values above DG. The indices obtained by this quantitative method (the extracted hole values) were compared with the observer evaluations (the observed hole values). In addition, the contrast-to-noise ratio (CNR) of the shallowest detectable holes and the deepest undetectable holes were measured to evaluate the contribution of CNR to detectability. Results: The results of this evaluation method corresponded almost exactly with the evaluations made by observers. The extracted hole values reflected the influence of different tube voltages. All extracted holes had an area with a CNR of $1.5. Conclusions: This quantitative method of evaluating CBCT image quality may be more useful and less time-consuming than evaluation by observation..
26. Effectiveness of imaging modalities for screening IgG4-related dacryoadenitis and sialadenitis (Mikulicz's disease) and for differentiating it from Sjögren's syndrome (SS), with an emphasis on sonography..
27. Erina Kitamoto, Toru Chikui, Shintaro Kawano, Masahiro Ohga, Kouji Kobayashi, Yoshio Matsuo, Takashi Yoshiura, Makoto Obara, Hiroshi Honda, Kazunori Yoshiura, The Application of Dynamic Contrast-Enhanced MRI and Diffusion-Weighted MRI in Patients with Maxillofacial Tumors, ACADEMIC RADIOLOGY, 10.1016/j.acra.2014.08.016, 22, 2, 210-216, 2015.02, Rationale and Objectives: To elucidate the characteristics of four types of tumors, including squamous cell carcinoma (SCC), malignant lymphoma (ML), malignant salivary gland tumors (MSGTs), and pleomorphic adenoma (Pleo), in the maxillofacial region using dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) and diffusion-weighted MRI (DW-MRI) data.
Materials and Methods: A total of 59 tumors were included in this research. DCE-MRI and DW-MRI were performed. We applied the Toffs and Kermode model (TK model) for the DCE-MRI data and obtained three dependent parameters: the influx forward volume transfer constant into the extravascular extracellular space from the plasma (K-trans), the fractional volume of extravascular extracellular space per unit volume of tissue (v(e)), and the fractional volume of plasma (v(p)).
Results: Among the K-trans values, there were no significant differences between the three types of malignant tumors; however, there was a significant difference between the SCC and Pleo (P =.0099). The ve values of the Pleo were highest, with significant differences compared to the other categories (SCC, P = .0012; ML, P = .0017; and MSGT, P = .041). The ML had the lowest ve values, and there were significant differences between ML and the other two types of malignant tumors (SCC, P = .0278 and MSGT, P = .0062). In 14 (24%) cases, apparent diffusion coefficient (ADC) could not be measured because of poor image quality. The ADC values of the ML. were lowest, whereas those of Pleo were highest, similar to that observed for V-e.
Conclusions: The Pleo tumors had lower K-trans values and higher v(e) values, which are useful for differentiating them from the malignant tumors. Moreover, the v(e) was also useful for establishing a diagnosis of ML..
28. Tatsushi Tokuyasu, Kazuhiko Toshimitsu, 岡村 和俊, 吉浦 一紀, Virtual palpation simulator for dental education., ICIC Express Letters, 6, 1, 181-185, 6:1, 181-185, 2015.01.
29. Mayumi Shimizu, Dai Ogawa, Kazutoshi Okamura, Toshiyuki Kawazu, Toru Chikui, Kazunori Yoshiura, Dentigerous cysts with calcification mimicking odontogenic tumors: differential diagnosis by CT, ORAL RADIOLOGY, 10.1007/s11282-014-0173-5, 31, 1, 14-22, 2015.01, This study aimed at clarifying whether we can differentiate dentigerous cysts with calcified substances from other odontogenic tumors that include calcification and the crown of an unerupted tooth by CT findings.
We retrospectively selected histopathologically confirmed cases that included calcified substances and the crown of an unerupted tooth inside. There were 22 cases with eight pathological categories. Besides seven odontogenic tumors, we included dentigerous cysts, which were usually recognized without calcification within the lesions. We divided the cases into two groups: 14 cases of odontogenic tumors and 8 cases of dentigerous cysts. Cases were analyzed for various CT findings such as continuity with the alveolar crest, bone sclerosis around the lesion, and sizes and shapes of high CT value substances, as well as demographic factors. Comparisons between the groups for each analytical factor were performed.
Dentigerous cysts with dystrophic calcification showed unique CT findings such as bone sclerosis around the lesion, continuity with the alveolar crest, and small scattered calcified substances near the crown of an unerupted tooth, compared with typical dentigerous cysts and other odontogenic tumors. On the other hand, odontogenic tumors showed various patterns in the location and distribution of high CT value substances, and we could only differentiate odontoma using its very high CT values.
Although the patterns of calcification were not the main characteristic findings, it may be possible to differentiate dentigerous cysts with dystrophic calcification from odontogenic tumors by their other characteristic CT findings, and unnecessary extensive surgery can also be avoided..
30. 清水 真弓, D Ogawa, 岡村 和俊, 河津 俊幸, 筑井 徹, 吉浦 一紀, Dentigerous cysts with calcification mimicking odontogenic tumors: differential diagnosis by CT., Oral Radiol, 30, 1, 173-175, 30:173-175, 2014.06.
31. Tatsushi Tokuyasu, Kazuhiko Toshimitsu, 岡村 和俊, 吉浦 一紀, Construction of Virtual Patient Model for Maxillofacial Palpation Training System., International Journal of Artificial Life and Robotics, 19, 2, 176-180, 19:2, 176-180, 2014.06.
32. Yuko Nakamura, KENJI TOKUMORI, Takashi Yoshiura, K Kobayashi, Y Nakamura, Hiroshi Honda, Kazunori Yoshiura, TK Got0, Localization of the primary taste cortex by contrasting passive and attentive conditions, Exp Brain Res, 227, 2, 185-197, 227:185-197, 2013.06, It remains unclear how the cerebral cortex of humans
perceives taste temporally, and whether or not such
objective data about the brain show a correlation
with the current widely used conventional methods of
taste–intensity sensory evaluation. The aim of this study
was to investigate the difference in the time–intensity
profile between salty and sweet tastes in the human brain.
The time–intensity profiles of functional MRI (fMRI) data of
the human taste cortex were analyzed using finite impulse
response analysis for a direct interpretation in terms
of the peristimulus time signal. Also, time–intensity
sensory evaluations for tastes were performed under the
same condition as fMRI to confirm the reliability of the
temporal profile in the fMRI data. The time–intensity
profile for the brain activations due to a salty taste changed
more rapidly than those due to a sweet taste in the
human brain cortex and was also similar to the
time–intensity sensory evaluation, confirming the reliability
of the temporal profile of the fMRI data. In conclusion,
the time–intensity profile using finite impulse response
analysis for fMRI data showed that there was a temporal
difference in the neural responses between salty and
sweet tastes over a given period of time. This indicates
that there might be taste-specific temporal profiles of
activations in the human brain..
33. Yukiko Nishioka Kami, Toru Chikui, Tomoko Shiraishi, Kenji Yuasa, Kazunori Yoshiura, A new method for displaying the lingual artery using high-resolution three-dimensional phase-contrast magnetic resonance angiography, Int J Oral Maxillofac Surg, 42, 1494-1498, 42: 1494-1498, 2013.05.
34. Nakamura Y, Goto KT, Tokumori K, Yoshiura T, Kobayashi K, Nakamura Y, Honda H, Ninomiya Y, Yoshiura K, The temporal change in the cortical activations due to salty and sweet tastes in humans: fMRI and time–intensity sensory evaluation, NeuroReport, 23, 400-404, 23:400-404, 2012.05, It remains unclear how the cerebral cortex of humans
perceives taste temporally, and whether or not such
objective data about the brain show a correlation
with the current widely used conventional methods of
taste–intensity sensory evaluation. The aim of this study
was to investigate the difference in the time–intensity
profile between salty and sweet tastes in the human brain.
The time–intensity profiles of functional MRI (fMRI) data of
the human taste cortex were analyzed using finite impulse
response analysis for a direct interpretation in terms
of the peristimulus time signal. Also, time–intensity
sensory evaluations for tastes were performed under the
same condition as fMRI to confirm the reliability of the
temporal profile in the fMRI data. The time–intensity
profile for the brain activations due to a salty taste changed
more rapidly than those due to a sweet taste in the
human brain cortex and was also similar to the
time–intensity sensory evaluation, confirming the reliability
of the temporal profile of the fMRI data. In conclusion,
the time–intensity profile using finite impulse response
analysis for fMRI data showed that there was a temporal
difference in the neural responses between salty and
sweet tastes over a given period of time. This indicates
that there might be taste-specific temporal profiles of
activations in the human brain..
35. Toru Chikui, E Kitamoto, Shintaro Kawano, Tsuyoshi Sugiura, M Obara, AW Shimonetti, M Hatakenaka, Y Matsuo, S Koga, M Ohga, Katsumasa Nakamura, Kazunori Yoshiura, Pharamacokinetic analysis based on dynamic contrast-enhanced MRI for evaluating tumor response to preoperative therapy for oral cancer, J Magn Reson Imaging, 36, 3, 589-597, 36(3):589-597, 2012.03.
36. Tomoko Shiraishi, Toru Chikui, Daisuke Inadomi, Toyohiro Kagawa, Kazunori Yoshiura, Kenji Yuasa, Evaluation of diffusion parameters and T-2 values of the masseter muscle during jaw opening, clenching, and rest, ACTA RADIOLOGICA, 10.1258/ar.2011.110136, 53, 1, 81-86, 53:81-86, 2012.02, Background: Diffusion-weighted imaging (DWI) and diffusion-tensor imaging (DTI) can be used to evaluate changes that accompany skeletal muscle contraction.
Purpose: To investigate whether jaw opening or closure affect the diffusion parameters of the masseter muscles (MMs).
Material and Methods: Eleven healthy volunteers were evaluated. Diffusion-tensor images were acquired to obtain the primary (lambda(1)), secondary (lambda(2)), and tertiary eigenvalues (lambda(3)). We estimated these parameters at three different locations: at the level of the mandibular notch for the superior site, the level of the mandibular foramen for the middle site, and the root apex of the mandibular molars for the inferior site.
Results: Both lambda(2) and lambda(3) during jaw opening were significantly lower than that at rest at the superior (P = 0.006, P < 0.0001, respectively) and middle site (P = 0.004, P = 0.0001, respectively); however, the change in lambda(1) was not significant. At the lower site, no parameter was significantly different at rest and during jaw opening. There was no significant difference in T2 between at rest (40.3 +/- 4.4 ms) and during jaw opening (39.2 +/- 2.7 ms; P = 0.12). The changes induced by jaw closure were marked at the inferior site. In the middle and inferior sites, the three eigenvalues were increased by jaw closure, and the changes in lambda(1) (P = 0.0145, P = 0.0107, respectively) and lambda(2) (P = 0.0003, P = 0.0001) were significant (especially lambda(2)).
Conclusion: The eigenvalues for diffusion of the MM were sensitive to jaw position. The recruitment of muscle fibers, specific to jaw position, reflects the differences in changes in muscle diffusion parameters..
37. Kami YN, Chikui T, Okamura K, Kubota Y, Oobu K, Yabuuchi H, Nakayama E, Hashimoto K, Yoshiura K, Imaging findings of neurogenic tumours in the head and neck region, Dentomaxillofac Radiol, 41, 1, 18-23, 41:18-23, 2012.01.
38. Kazutoshi Okamura, Kazunori Yoshiura, Masato Tatsumi, Toshiyuki Kawazu, Toru Chikui, Mayumi Shimizu, Tazuko K. Goto, A new method for evaluating perceptible contrast information in digital intraoral radiographic systems, ORAL RADIOLOGY, 10.1007/s11282-011-0068-7, 27, 2, 98-101, 27:98-101, 2011.12, Objectives To evaluate four digital intraoral radiographic systems using perceptibility curves (PCs) in a grayscale domain and to clarify the usefulness of this new method.
Methods Four systems were evaluated, namely the CDR, Dixel, Digora, and Digora Optime. An aluminum phantom with 12 steps was radiographed using all four systems. The mean gray values and their standard deviations were measured for each step as well as the background of the images for each device. The minimum perceptible gray level differences at a given exposure were calculated from the mean gray values and standard deviations, and a PC in the grayscale domain was constructed at each exposure for all devices. The area under the PC was assumed to be the perceptible contrast information at that exposure for each system. By combining the PCs at all exposures for each system, the maximum perceptible contrast information in each system was calculated. The correlation between the perceptible contrast information and the number of perceptible holes by observers at each exposure was examined for all four digital systems.
Results The Dixel and Digora Optime showed similar PCs, and their minimum perceptible gray level differences were the smallest among the systems. The correlation between the number of perceptible holes and the areas under the PCs at each exposure for the four systems was relatively high (r = 0.92).
Conclusions The areas under the PCs in a grayscale domain were highly correlated with observer performance. This method can be used to evaluate the image quality of new digital systems..
39. Toru Chikui, Shintaro Kawano, Toshiyuki Kawazu, Masamitsu Hatakenaka, Syouzou Koga, Masahiro Ohga, Yoshio Matsuo, Syunya Sunami, Tsuyoshi Sugiura, Yoshiyuki Shioyama, Makoto Obara, Kazunori Yoshiura, Prediction and monitoring of the response to chemoradiotherapy in oral squamous cell carcinomas using a pharmacokinetic analysis based on the dynamic contrast-enhanced MR imaging findings, EUROPEAN RADIOLOGY, 10.1007/s00330-011-2102-x, 21, 8, 1699-1708, 21(8):1699-1708, 2011.08, To evaluate whether a pharmacokinetic analysis is useful for both predicting and monitoring the response to chemoradiotherapy (CRT) in oral cancer.
Patients with oral squamous cell carcinoma treated with preoperative CRT and surgery were enrolled. They underwent dynamic contrast-enhanced MRI before (n = 23), and after CRT (n = 20). We estimated four parameters: arrival time of contrast medium (TA), exchange rate constant from the extracellular extravascular space (EES) to plasma (k(ep)), elimination of contrast medium from the central compartment (k(el)) and an amplitude scaling constant (AH) using the Brix model. The histological evaluation of the effects of CRT was performed according to Ohboshi and Shimosato's classification. We analysed the correlation between the parameters and the histological evaluation.
The pre-CRT AH between the responders and non-responders was significantly different (P = 0.046), however, the three parameters (TA, K-ep, K-el) were not significantly different among the groups (P = 0.76, P = 0.60, P = 0.09). As AH decreased, the tumour response improved. The change in the AH between the pre- and post-CRT of responders was significantly higher than that of non-responders (P = 0.043).
The AH, which is affected by the ratio of the EES, was an important parameter for predicting and monitoring the tumour response to CRT..
40. T. Shiraishi, T. Chikui, K. Yoshiura, K. Yuasa, Evaluation of T-2 values and apparent diffusion coefficient of the masseter muscle by clenching, DENTOMAXILLOFACIAL RADIOLOGY, 10.1259/dmfr/15607259, 40, 1, 35-41, 40(1):35-41, 2011.01, Objective: The aim of this study was to evaluate the changes in T-2 values and apparent diffusion coefficient (ADC) in the masseter muscle by clenching in healthy volunteers.
Methods: 37 volunteers were enrolled in the study. We measured bite force using pressure-sensitive paper and a T-2 map. The ADC map was obtained at rest, during clenching, immediately after and 5 min after clenching. The spin-echo sequence was used to calculate T-2, and single-shot spin-echo echo planar imaging was used to calculate the ADC. The motion-probing gradients (MPGs) were applied separately along the posterior-to-anterior (PA), right-to-left (RL) and superior-to-inferior (SI) directions, with b values of 0, 300 and 600 s mm(-2) in each direction. ADC-PA, ADC-RL, and ADC-SI values were obtained, and we calculated the ADC-iso for the mean diffusivity.
Results: There were no significant differences between the stronger and weaker sides of bite force before, during or 5 min after clenching for T-2 and ADC. The bite force had little effect on these parameters; thus, we used the average of the two sides for the following analyses. Time course analysis of ADC-iso, ADC-PA, ADC-RL and ADC-SI demonstrated a marked increase after clenching and a rapid decrease immediately after clenching, although they did not completely return to the initial values; however, the change in ADC-RL was significantly greater than those in ADC-PA or ADC-SI (P < 0.001 each). The changes in T-2 were similar to those of ADC, although not as marked.
Conclusions: ADC (especially ADC-RL) was altered by contraction of the masseter muscle. Dentomaxillofacial Radiology (2011) 40, 35-41. doi: 10.1259/dmfr/15607259.
41. Tutsumi K, Chikui T, Okamura K, Yoshiura K, Accuracy of Linear Measurement and the Measurement Limits of Thin Objects with Cone Beam Computed Tomography: Effects of Measurement Directions and of Phantom Locations in the Fields of View, J Oral Max Impl, 26, 1, 91-100, 26(1):91-100, 2011.01.
42. Chikui T, Shiraishi T, Tokumori K, Inatomi D, Hatakenaka M, Yuasa K, Yoshiura K, Assessment of the sequential change of the masseter muscle by clenching: a quantitative analysis of T1, T2, and the signal intensity of the balanced steady-state free precession, Acta Radiol, 51, 669-678, 51:669-678, 2010.09.
43. Chikui T, Shiraishi T, Ichihara T, Kawazu T, Hatakenaka M, Kami Y, Yuasa K, Yoshiura K, Effect of clenching on T2 and diffusion parameters of the masseter muscle, Acta Radiologica, 2010(1):58-63, 2010.01.
44. Toru Chikui, Kenji Tokumori, Ryosuke Zeze, Tomoko Shiraishi, Takahiro Ichihara, Masamitsu Hatakenaka, Kazunori Yoshiura, A fast Look-Locker method for T1 mapping of the head and neck region, Oral Radiol, 25:22-29, 2009.12.
45. Toru Chikui, Mayumi Shimizu, Toshiyuki Kawazu, Kazutoshi Okamura, Tomoko Shiraishi, Kazunori Yoshiura, A QUANTITATIVE ANALYSIS OF SONOGRAPHIC IMAGES OF THE SALIVARY GLAND: A COMPARISON BETWEEN SONOGRAPHIC AND SIALOGRAPHIC FINDINGS, ULTRASOUND IN MEDICINE AND BIOLOGY, 10.1016/j.ultrasmedbio.2009.03.005, 35, 8, 1257-1264, 35(8):1257-1264, 2009.08, We performed three quantitative analyses (particle analysis, fractional Brownian motion [fBM] model analysis, two-dimensional [2-D] fractal analysis) of the ultrasonographic (US) images of the salivary gland and evaluated whether the obtained indices correlated with the sialographic stage of Rubin-Holt. Our study included 192 patients suspected of having Sjogren's syndrome (SS). In 89 patients, sialography demonstrated abnormal findings. Based on a particle analysis, we calculated both the average size of the particles (avg-area) and the area ratio to evaluate the presence of hypoechoic areas and echogenic lines, which are characteristic of SS. According to the fBM model, we calculated the Hurst index of the original image (Hurst-ori) and the background-subtracted image (Hurst-bs) to evaluate the complexity of the pixel value distribution. We also obtained the 2-D fractal dimension (2-D-FD) to evaluate the complexity of the contour lines. We entered these indices of the parotid glands (PG) into a logistic regression analysis and evaluated which indices were useful predictors for detecting all abnormal sialographic stage. Significant differences were observed between the normal and abnormal groups in all five indices of the PG (Mann-Whitney U test) and all five indices were correlated with the Rubin-Holt stage (Spearman's Rank Correlation Test). As the Rubin-Holt stage became more severe, both the Hurst-ori and 2-D-FD became smaller. Alternatively, the Hurst-bs, avg-area, and area ratio became higher. Three indices (avg-area, area ratio and Hurst-ori) were selected as useful predictors for detecting abnormal sialographic stages. This quantitative analysis system is therefore considered to have potentially useful clinical applications for the detection of abnormal sialographic findings. (E-mail: chikui@rad.dent.kyushu-u.ac.jp) (C) 2009 World Federation for Ultrasound in Medicine & Biology..
46. Sonographic diagnosis for Mikulicz disease..
47. Sonographic diagnosis of Sjögren syndrome: evaluation of parotid gland vascularity as a diagnostic tool..
48. Yukiko N. Kami, Tazuko K. Goto, Kenji Tokumori, Takashi Yoshiura, Koji Kobayashi, Yasuhiko Nakamura, Hiroshi Honda, Yuzo Ninomiya, Kazunori Yoshiura, The development of a novel automated taste stimulus delivery system for fMRI studies on the human cortical segregation of taste, JOURNAL OF NEUROSCIENCE METHODS, 10.1016/j.jneumeth.2008.04.009, 172, 1, 48-53, 172(1):48-53, 2008.07, fMRI indicated that the primary taste cortex is activated not only by taste but also by non-taste information from oral stimuli. Head movements caused by swallowing are very critical problem in fMRI and inherent difficulties to modulate taste stimuli in the mouth exist to elucidate functional segregation of human brain. We developed a novel automated taste stimulus delivery system for fMRI studies to segregate the pure taste area in the primary taste cortex in humans. As a novel intra-oral device, an elliptic cylinder was attached to an individual mouthpiece and then subject placed the tongue tip in it. Using a computer-controlled extra-oral device, the solutions ran through the intra-oral device in constant conditions. Three adult volunteers participated in the experimental session, alternately consisting of 30 pairs of taste stimuli (0.5 mol/l sucrose solution) and control (water) blocks. The typical findings of the three subjects revealed, activation only in the primary taste cortex (P < 0.001), and none in the secondary taste cortex. This is the first system that delivers the taste stimuli automatically to a standardized area on the subject's tongue under constant conditions, thus allowing us to successfully segregate the pure taste area in the primary taste cortex in humans. (C) 2008 Elsevier B.V. All rights reserved..
49. The accuracy of 3-dimensional magnetic resonance 3D vibe images of the mandible: an in vitro comparison of magnetic resonance imaging and computed tomography..
50. Nakayama E, Okamura K, Mitsuyasu T, Kawazu T, Nakamura N, Nakamura S, Yoshiura K, A newly developed interventional sialendoscope for a completely nonsurgical sialolithectomy using intracorporeal electrohydraulic lithotripsy, J Oral Maxillofac Surg, 103(4): 550-559, 2007.04.
51. Sonographic diagnostic criteria for screening Sjögren's syndrome..
52. Goto KT, Nishida S, Yahagi M, Langenbach GEJ, Nakamura Y, Tokumori K, Sakai S, Yabuuchi H, Yoshiura K, Size and Orientation of Masticatory Muscles in Patients with Mandibular Laterognathim, JDR, 85(6): 552-556, 2006.06.
53. Quantitative analyses of sonographic images of the parotid gland in patients with Sjögren's syndrome..
54. M Shimizu, N Osa, K Okamura, K Yoshiura, CT analysis of the Stafne's bone defects of the mandible, DENTOMAXILLOFACIAL RADIOLOGY, 10.1259/dmfr/71115878, 35, 2, 95-102, 35(2): 95-102, 2006.03, Objective: To investigate the aetiology Of Stafne's bone defects by analysing the CT findings of two types of defects, which appeared differently on panoramic radiographs.
Methods: 32 lesions with suspicion of the Stafne's bone defect on a panoramic radiograph were categorised into two groups: typical "Stafne type", which showed the connection to the base of the mandible, and non-typical "Cyst type", which showed no connection. Age, sex, the existence of hypertension and the following CT findings: location. size and inner content of the defect. existence of expansion of the buccal cortical bone, and location of submandibular glands, were analysed.
Results: There were 14 "Stafne type" and 17 "Cyst type" oil the panoramic radiographs. One lesion in the "Cyst type" was a true cystic lesion and was excluded from further review. The "Stafne type" was seen primarily in the posterior and inferior locations, while the "Cyst type" was seen in the anterior and superior locations on the CT. The size of the defect was significantly larger in the "Stafne type". Buccal cortical expansion was observed only in three lesions in the "Stafne type". While the "Cyst type" contained mainly fatty tissue, the "Stafne type" contained other soft tissues. Though the submandibular glands on the defect side were located anteriorly in both types compared with those on the contralateral side and on the control patients, they spread mainly outwards in the "Stafne type".
Conclusion: The Stafne's bone defects are thought to be caused by the dislocated submandibular gland. The differences between the two types might occur as a result of a different location of the submandibular gland..
55. Goto TK, Nishida S, Nakayama E, Nakamura Y, Sakai S, Yabuuchi H, Yoshiura K, Correlation of mandibular deviation with temporomandibular joint MR dimensions, MR disk position, and clinical symptoms, Oral Surg Oral Med Oral Pathol Oral Radiol Endod, 10.1016/j.tripleo.2005.05.063, 100, 6, 743-749, 100(6): 743-749, 2005.12.
56. Yoshiura K, Okamura K, Tokumori K, Nakayama E, Chikui T, Goto TK, Shimizu M, Kawazu T, Correlation between diagnostic accuracy and perceptibility, Dentomaxillofac. Radiol., 10.1259/dmfr/13550415, 34, 6, 350-352, 34(6): 350-352, 2005.11.
57. Sonographic texture characterization of salivary gland tumors by fractal analyses..
58. TK Goto, M Yahagi, Y Nakamura, K Tokumori, GEJ Langenbach, K Yoshiura, In vivo cross-sectional area of human jaw muscles varies with section location and jaw position, JOURNAL OF DENTAL RESEARCH, 84, 6, 570-575, 84(6): 570-575, 2005.06, Muscle cross-sectional area (CSA) is used as a measure for maximum muscle force. This CSA is commonly determined at one location within the muscle and for one jaw position. The purpose of this study was to establish a method to standardize the analysis of the CSA of the masticatory muscles in vivo, and to compare the CSAs along their entire length for two different jaw positions ( opened and closed). The CSAs in the planes perpendicular to the long axes of the masseter, medial, and lateral pterygoid muscles were measured in ten normal young adult subjects by magnetic resonance imaging. Our results showed large differences among the muscles and a nonuniform change in CSA after jaw-opening. The method enables the CSA measurement to be standardized in vivo, and allows for a correct comparison of CSAs in different skull morphologies..
59. Yoshiura K, Nakayama E, Shimizu M, Goto TK, Chikui T, Kawazu T, Okamura K, Effects of the automatic exposure compensation on the proximal caries diagnosis, Dentomaxillofac. Radiol., 10.1259/dmfr/88681265, 34, 3, 140-144, 34(3): 140-144, 2005.05.
60. E Nakayama, K Sugiura, H Ishibashi, K Oobu, Kobayashi, I, K Yoshiura, The clinical and diagnostic imaging findings of osteosarcoma of the jaw, DENTOMAXILLOFACIAL RADIOLOGY, 34, 3, 182-188, 34(3): 182-188, 2005.05, Objective: To clarify the valuable clinical features and diagnostic imaging findings regarding the diagnosis of osteosarcoma of the jaw (OSJ).
Materials and methods: The initial symptoms and diagnostic imaging findings of 10 patients with OSJ were analysed. The points analysed on the diagnostic images were as follows: any widening of the periodontal ligament space of the teeth on the periphery of the OSJ; the presence of radial spicules and Codman's triangle; any signs of bone destruction; and the patterns of osteogenesis.
Results: All patients had pain and/or swelling of the affected site, and all OSJs, except for one edentulous case, showed a widening of the periodontal ligament space of the teeth on the periphery of the OSJ. Radial spicules or Codman's triangle were observed in only three cases (30%). Four out of five mandibular OSJs were osteolytic or osteolytic dominant with bone destruction, while, in contrast, four out of five maxillary OSJs were osteogenic or osteogenic dominant, and three out of the four maxillary OSJs did not show bone destruction. The osteogenic OSJ without bone destruction was similar to some benign cemento-osseous lesions of the jaw and thus was difficult to diagnose as OSJ based on the diagnostic imaging findings alone.
Conclusion: Even though some OSJ showed features similar to the benign tumours of the jaw bone based on the diagnostic imaging findings, the pain and swelling of the affected site, and the widening of the periodontal ligament space of the teeth on the periphery of OSJ were considered to be common findings, which may help in making an accurate diagnosis of OSJ in this limited series..
61. Multiple sialolithiasis in the parotid gland with Sjögren's syndrome and its sonographic findings--report of 3 cases..
62. Interpretation of the origin of a submandibular mass by CT and MRI imaging..
63. XQ Shi, G Li, K Yoshiura, U Welander, Perceptibility curve test for conventional and colour-coded radiographs, DENTOMAXILLOFACIAL RADIOLOGY, 10.1259/dmfr/273752105, 33, 5, 318-322, 33(5): 318-322, 2004.09, Objective: A colour scale has been developed as a complement to the grey scale in radiographs. The aim of the present study was to compare colour-coded with conventional black-and-white radiographs in terms of the perceptibility curve test.
Material and methods: Twelve digital radiographs were exposed on a test object from low to high exposures and recorded using the DIXI system (Planmeca Oy, Helsinki, Finland). An aluminium test object was used containing ten object details in the form of holes with depths ranging from 0.03 mm to 0.30 mm in steps of 0.03 +/- 0.01 mm. The new colour scale was used to transform the conventional black-and-white radiographs into colour radiographs by specially designed software. Ten observers were asked to analyse four sets of radiographs, i.e. colour-coded and black-and-white radiographs, and reversed colour-coded and reversed black-and-white radiographs. The object detail having the lowest perceptible contrast in each radiograph was registered for each observer. Perceptibility curves were plotted based on the mean value of observer data.
Results: Results from the perceptibility curve test showed that the information in colour-coded radiographs was at least as good as that in black-and-white radiographs. In fact, in the lower exposure range, colour-coded radiographs exhibited better perception than conventional black-and-white radiographs.
Conclusion: Radiographs that are colour-coded with the applied colour scale may be used as an alternative to conventional black-and-white radiographs..
64. M. Mastoris, K. Yoshiura, U. Welander, K. Tsiklakis, E. Papadakis, G. Li, Psychophysical properties of a new F-speed intraoral film, Dentomaxillofacial Radiology, 10.1259/dmfr/87969619, 33, 3, 158-163, 33(3): 158-163, 2004.05, Objectives: To compare the psychophysical properties of the new Kodak InSight F-speed intraoral dental film with those for the E-speed Ektaspeed Plus film by means of the perceptibility curve (PC) test. Methods: A specially designed test object was used. The test object was made of aluminium and was 10 mm thick. It contained ten holes, contrast details, with the same diameter of 1.5 mm but with different depths. The depths ranged from 0.03 mm to 0.30 mm in steps of 0.03 mm. The holes were placed randomly within a square area with a total of 16 possible positions. Radiographs of the test object were obtained over the full exposure ranges of the two films. A Combex DX-907 dental X-ray unit was used operating at 10 mA and two tube potentials, 70 kVp and 90 kVp. The focus-to-object distance was 50 cm. Ten observers evaluated the radiographs under uniform artificial lighting using a view box and stated the number of perceptible representations of contrast details. In order to construct perceptibility curves, absolute values of the reciprocal of the minimum perceptible logarithmic exposure differences, 1/(DlogE)min, were plotted as functions of the logarithm of exposures, logE, registered by the tested films. Comparisons between the two films were made separately for the two tube potentials, 70 kVp and 90 kVp. Results: The results are presented graphically. PCs for the InSight film had higher peaks than those for the Ektaspeed Plus film. This indicates that the viewers were able to perceive smaller exposure differences in the former compared with the latter. PCs for the InSight film were shifted towards the left along the exposure axis relative to the PCs for the Ektaspeed Plus film indicating that the former film is more sensitive than the latter. The integrals of the PCs for InSight film were larger than those for Ektaspeed film indicating superior psychophysical properties of the InSight film. Conclusions: From the point of view of perception, the new InSight film has such psychophysical properties in comparison with Ektaspeed Plus film that it will be the more favourable of the two in clinical radiographic practice. © 2004 The British Institute of Radiology..
65. Yoshiura K, Welander U, McDavid WD, Li G, Shi X-Q, Nakayama E, Shimizu M, Okamura K, Kanda S., Comparison of the psychophysical properties of various intraoral film and digital systems by means of the perceptibility curve test, Dentomaxillofac Radiol, 10.1259/dmfr/29102849, 33, 2, 98-102, 33(2): 98-102, 2004.03.
66. Kawazu T., Araki K., Yoshiura K., Nakayama E., and Kanda S., Application of neural networks to the prediction of lymph node metastasis in oral cancer, Oral Radiol, 19(2): 137-142, 2003.12.
67. E Nakayama, K Yoshiura, S Ozeki, HN Nakayama, T Yamaguchi, H Yoshikawa, S Kanda, M Ohishi, K Shirasuna, The correlation of histologic features with a panoramic radiography pattern and a computed tomography pattern of bone destruction in carcinoma of the mandibular gingiva, ORAL SURGERY ORAL MEDICINE ORAL PATHOLOGY ORAL RADIOLOGY AND ENDODONTICS, 10.1016/S1079-2104(03)00458-X, 96, 6, 774-782, 96(6): 774-782, 2003.12, Objective. We sought to clarify the correlation among a computed tomography (CT) or a panoramic radiography (PR) pattern of bone destruction, a histologic pattern of bone destruction, and a mode of invasion in carcinoma of the mandibular gingiva.
Study design. CT images, panoramic radiographs, and decalcified, hematoxylin-eosin-stained preparations of the excised mandibular bone of 62 patients with carcinoma of the mandibular gingiva were retrospectively evaluated. Each computed tomograph, panoramic radiograph, and the histologic pattern of bone destruction was classified as 1 of 5 types: erosive, erosive and partly mixed, mixed, mixed and partly invasive, or invasive. The mode of invasion of the tumor was also assessed with a hematoxylin-eosin-stained preparation of the initial biopsy specimen. The relationships among the CT pattern, the PR pattern, the histologic pattern of bone destruction, and the mode of invasion of the tumor were statistically analyzed by using the Spearman rank correlation test.
Results. The CT pattern (P = .005) and the PR pattern (P = .003) were significantly correlated with the histologic pattern with respect to the bone destruction. The CT pattern (P = .996), the PR pattern (P = .997), and the histologic pattern (P = .521) of bone destruction were not correlated with the mode of invasion seen in the biopsy specimen.
Conclusion. The CT pattern and the PR pattern of bone destruction reflect the histologic pattern of bone destruction caused by carcinoma of the mandibular gingiva but are not associated with the mode of invasion of the tumor..
68. G Li, U Welander, K Yoshiura, XQ Shi, WD McDavid, Perceptibility curve test for digital radiographs before and after correction for attenuation and correction for attenuation and visual response, DENTOMAXILLOFACIAL RADIOLOGY, 10.1259/dmfr/64530544, 32, 6, 372-378, 32(6): 372-378, 2003.11, Objective: Two digital image processing methods, correction for X-ray attenuation and correction for attenuation and visual response, have been developed. The aim of the present study was to compare digital radiographs before and after correction for attenuation and correction for attenuation and visual response by means of a perceptibility curve test.
Material and methods: Radiographs were exposed of an aluminium test object containing holes ranging from 0.03 mm to 0.30 mm with increments of 0.03 mm. Fourteen radiographs were exposed with the Dixi system (Planmeca Oy, Helsinki, Finland) and twelve radiographs were exposed with the F1 iOX system (Fimet Oy, Monninkyla, Finland) from low to high exposures covering the full exposure ranges of the systems. Radiographs obtained from the Dixi and F1 iOX systems were 12 bit and 8 bit images, respectively. Original radiographs were then processed for correction for attenuation and correction for attenuation and visual response. Thus, two series of radiographs were created. Ten viewers evaluated all the radiographs in the same random order under the same viewing conditions. The object detail having the lowest perceptible contrast was recorded for each observer. Perceptibility curves were plotted according to the mean of observer data.
Results: The perceptibility curves for processed radiographs obtained with the F1 iOX system are higher than those for originals in the exposure range up to the peak, where the curves are basically the same. For radiographs exposed with the Dixi system, perceptibility curves for processed radiographs are higher than those for originals for all exposures. Perceptibility curves show that for 8 bit radiographs obtained from the F1 iOX system, the contrast threshold was increased in processed radiographs up to the peak, while for 12 bit radiographs obtained with the Dixi system, the contrast threshold was increased in processed radiographs for all exposures. When comparisons were made between radiographs corrected for attenuation and corrected for attenuation and visual response, basically no differences were found.
Conclusion: Radiographs processed for correction for attenuation and correction for attenuation and visual response may improve perception, especially for 12 bit originals..
69. Li G, Yoshiura K, Shi X-Q, Welander U, McDavid WD, Physical properties of a system for direct acquisition of digital intraoral radiographs, Oral Radiol, 2003.06.
70. Takashima A, Yoshiura K, Tokumori K, Kawazu T, Kanda S, Quantitative analysis of radiological changes in alveolar bone around connected osseo-integrated dental implants and natural abutment teeth, Oral Radiol, 2003.06.
71. Yoshiura K, Welander U, Li G, Shi X-Q, McDavid WD, Kawazu T, Tatsumi M, Okamura K, Kanda S, Analysis of different approaches to constructing perceptibility curves, Oral Radiol, 2003.06.
72. Yoshiura K, Welander U, McDavid WD, Li G, Shi X-Q, Kawazu T, Tatsumi M, Matsuo T, Kanda S, Perceptibility curves for the Digora system, Dentomaxillofac Radiol, 10.1259/dmfr/25806978, 32, 3, 191-197, 2003.05.
73. Li G, Yoshiura K, Welander U, Shi X-Q, McDavid WD, Detection of approximal caries in digital radiographs before and after correction for attenuation and visual response. An in vitro study, Dentomaxillofac Radiol, 2002.05.
74. Welander U, Yoshiura K, Li G, Sallstrom P, McDavid WD, Correction for attenuation and visual response in digital radiography, Dentomaxillofac Radiol, 2002.05.
75. Li G, Yoshiura K, Welander U, Sallstrom P, McDavid WD, Visual linearization of the display of digital radiographs, Dentomaxillofac Radiol, 2002.05.
76. Yoshiura K, Welander U, Shi X-Q, Li G, Kawazu T, Tatsumi M, Okamura K, McDavid WD, Kanda S, Conventional and predicted Perceptibility Curves for contrast-enhanced direct digital intraoral radiographs, Dentomaxillofacial Radiology, 10.1038/sj.dmfr.4600607, 30, 4, 219-225, 2001.07.
77. Shimizu M, Tokumori K, Okamura K, Chikui T, Yoshiura K, Kanda S, Possibility of sialographic sonography: A Doppler phantom study, Oral Surg Oral Med Oral Pathol Oral Radiol Endod, 10.1067/moe.2001.113832, 91, 6, 719-727, 2001.06.
78. Okamura K, Tanaka T, Yoshiura K, Tokumori K, Yuasa K, Kanda S, Integration of a picture archiving and communication system with videocapture and computed radiography in a dental hospital, Dentomaxillofacial Radiology, 10.1038/sj.dmfr.4600599, 30, 3, 172-178, 2001.05.
79. Goto KT, Yoshiura K, Nakayama E, Yuasa K, Tabata O, Nakano T, Kawazu T, Tanaka T, Miwa K, Shimizu M, Chikui T, Okamura K, Kanda S, The combined use of US and MR imaging for the diagnosis of masses in the parotid region, Acta Radiologica, 10.1080/028418501127346305, 42, 1, 88-95, 2001.01.
80. K Yuasa, T Kawazu, N Kunitake, S Uehara, J Omagari, K Yoshiura, E Nakayama, S Kanda, Sonography for the detection of cervical lymph node metastases among patients with tongue cancer: Criteria for early detection and assessment of follow-up examination intervals, AMERICAN JOURNAL OF NEURORADIOLOGY, 21, 6, 1127-1132, 2000.06, BACKGROUND AND PURPOSE: Because the presence of cervical metastasis is one of the factors influencing the outcome of patients with carcinoma of the head and neck, its early detection is potentially very important. The purpose of this study was to evaluate the characteristic changes of cervical metastasis revealed by sonography during follow-up and to assess an adequate interval for follow-up sonography of the neck among patients with tongue cancer,
METHODS: Forty-three of 44 consecutive patients with squamous cell carcinoma of the tongue, who had undergone interstitial brachytherapy, were examined with sonography of the neck during the posttherapeutic follow-up period.
RESULTS: Seventeen cervical lymph node metastases were found in 12 of 43 patients during follow-up. Of these 17 cervical metastases, 16 (94.1%) were accurately diagnosed and one (5.9%) was misdiagnosed as nonmetastatic based on sonographic findings, Sonography of the neck performed in seven patients at an interval of less than 1 month since the last follow-up imaging showed 9 (90.0%) of 10 metastases increased by up to 2 mm in short-axis diameter. Five patients who were followed up at an interval of more than 1 month since the last followup imaging had seven metastases increase by 3 to 8 mm in short-axis diameter or a change of echogenicity in the internal structure of lymph nodes or both. Pathologic examinations showed extranodal spread in 3 (42.9%) of these 7 metastases.
CONCLUSION: Changes both in size and internal echogenicity can occur as quickly as 2 to 4 weeks between sonographic examinations. Therefore, in high-risk patients, or in those with suspicious sonographic findings, short-interval follow-up sonographic examinations are recommended at least during the first posttherapeutic year. Our findings suggest that follow-up sonography of the neck should be performed monthly, at least during the first posttherapeutic year..
81. Nakayama E, Yoshiura K, Yuasa K, Kanda S, Saitoh M, Kage W, Ikebe T, Ozeki S, Shinohara M, A study of the association between the prognosis of carcinoma of the mandibular gingiva and the pattern of bone destruction on computed tomography, Dentomaxillofac Radiol, 10.1038/sj.dmfr.4600527, 29, 3, 163-169, 2000.05.
82. Shimizu M, Tokumori K, Saitoh M, Miwa K, Yoshiura K, Kanda S, Sonographic analysis of rat submandibular glands in experimentally-induced sialadenitis, Dentomaxillofac Radiol, 10.1038/sj.dmfr.4600508, 29, 2, 90-96, 2000.01.
83. Nakayama E, Yoshiura K, Yuasa K, Tabata O, Araki K, Kanda S, Ozeki S, Shinohara M, Detection of bone invasion by gingival carcinoma of the mandible: a comparison of intraoral and panoramic radiography and computed tomography, Dentomaxillofac Radiol, 10.1038/sj.dmfr.4600480, 28, 6, 351-356, 1999.11.
84. Yoshiura K, Stamatakis HC, Welander U, McDavid WD, Shi X-Q, Ban S, Kawazu T, Tatsumi M, Kanda S, Physical evaluation of a system for direct digital intra-oral radiography based on a charge-coupled device, Dentomaxillofac Radiol, 10.1038/sj.dmfr.4600457, 28, 5, 277-283, 1999.09.
85. Yoshiura K, Stamatakis HC, Welander U, McDavid WD, Shi X-Q, Ban S, Kawazu T, Chikui T, Kanda S, Prediction of Perceptibility Curves of direct digital intraoral radiographic systems, Dentomaxillofac Radiol, 10.1038/sj.dmfr.4600450, 28, 4, 224-231, 1999.07.
86. Stamatakis HC, Yoshiura K, Shi X-Q, Welander U, McDavid WD, A Simplified method to obtain Perceptibility Curves for direct dental digital CCD detectors, Dentomaxillofac Radiol, 1999.03.
87. Yoshiura K, Kawazu T, Chikui T, Tatsumi M, Tokumori K, Tanaka T, Kanda S, Assessment of image quality in dental radiography, part 1 Phantom validity, Oral Surg Oral Med Oral Pathol Oral Radiol Endod, 10.1016/S1079-2104(99)70304-5, 87, 1, 115-122, 1999.01.
88. Yoshiura K, Kawazu T, Chikui T, Tatsumi M, Tokumori K, Tanaka T, Kanda S, Assessment of image quality in dental radiography, part 2 Optimum exposure conditions for detection of small mass changes in 6 intraoral radiography systems, Oral Surg Oral Med Oral Pathol Oral Radiol Endod, 10.1016/S1079-2104(99)70305-7, 87, 1, 123-129, 1999.01.
89. Shimizu M, Ussmueller J, Donath K, Yoshiura K, Ban S, Kanda S, Ozeki S, Shinohara M, Sonographic analysis of recurrent parotitis in children A comparative study with sialographic findings, Oral Surg Oral Med Oral Pathol Oral Radiol Endod, 10.1016/S1079-2104(98)90355-9, 86, 5, 606-615, 1998.11.
90. Yoshiura K, Stamatakis H, Shi X-Q, Welander U, McDavid WD, Kristoffersen J, Tronje G, The perceptibility curve test applied to direct digital dental radiography, Dentomaxillofac Radiol, 10.1038/sj.dmfr.4600332, 27, 3, 131-135, 1998.05.
91. Yoshiura, K., Tabata, O., Miwa, K., Tanaka, T., Shimizu, M., Higuchi, Y., Shinohara, M., Kanda, S., Computed tomographic features of calcigying odontogenic cysts, Dentomaxillofac Radiol, 10.1038/sj.dmfr.4600305, 27, 1, 12-16, 1998.01.
92. K YOSHIURA, Y HIGUCHI, Y ARIJI, M SHINOHARA, K YUASA, E NAKAYAMA, S BAN, S KANDA, INCREASED ATTENUATION IN ODONTOGENIC KERATOCYSTS WITH COMPUTED-TOMOGRAPHY - A NEW FINDING, DENTOMAXILLOFACIAL RADIOLOGY, 23, 3, 138-142, 1994.08, An increased attenuation area (IAA) is sometimes seen in the cystic cavity of odontogenic keratocysts (OKCs) on CT scans. The significance of IAA was compared radiologically and histologically in 26 cysts in which a provisional diagnosis of OKC has been made. First, the presence of IAA in the cystic cavity was assessed. Then, relationship between the presence of IAA and data obtained from the cysts, including the CT and histological findings and the visual appearance of the cyst contents, was evaluated. An IAA was frequently seen in large multilocular cysts. There was no relationship between the presence of IAA and aggressive features of the cyst on CT or the cyst contents. Histologically, subepithelial inflammation was, often observed in the cysts with IAA. In order to ascertain whether the IAA was due to the keratin mass, a CT scan of a bundle of hair in a water bath was performed and shown to have a similar density. Our study demonstrated that IAA in cystic cavities results from desquamated keratin. Since this seems to occur in long-standing or inflamed multilocular OKCs, it could be used as a significant finding in the diagnosis of OKC..