| 1. |
Yoshitaka Kise , Anne Moystad , Tore Bjornland , Mayumi Shimizu, Yoshiko Ariji, Chiaki Kuwada, Masako Nishiyama, Takuma Funakoshi, Kazunori Yoshiura, Eiichiro Ariji, Effects of 1 year of training on the performance of ultrasonographic image interpretation: A preliminary evaluation using images of Sjogren syndrome patients, Imaging Science in Dentistry, 10.5624/isd.20200294, 21, 2, 129-136, 2021.06. |
| 2. |
Maehara T, Munemura R, Shimizu M, Kakizoe N, Kaneko N, Murakami Y, Masafumi M, Kiyoshima T, Kawano S, Nakamura S., Tissue-infiltrating immune cells contribute to understanding the pathogenesis of Kimura disease: A case report, Medicine, 10.1097/MD.0000000000018300, 98, 50, 2019.12. |
| 3. |
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, Dentomaxillofac Radiol, 10.1259/dmfr.20190348, 49, 3, 20190348-20190348, 2020.02. |
| 4. |
Sakamoto M, Moriyama M, Shimizu M, Chinju A, Mochizuki K, Munemura R, Ohyama K, Maehara T, Ogata K, Ohta M, Yamauchi M, Ishiguro N, Matsumura M, Ohyama Y, Kiyoshima T, Nakamura S., The diagnostic utility of submandibular gland sonography and labial salivary gland biopsy in IgG4-related dacryoadenitis and sialadenitis: Its potential application to the diagnostic criteria., Mod Rheumatol., 10.1080/14397595.2019.1576271, 30, 2, 379-384, 2019.03. |
| 5. |
Mayumi Shimizu, Warangkana Weerawanich, Sonographic diagnosis in the head and neck region – From the educational lecture in the 56th general assembly and annual scientific congress of Japanese Society for Oral and Maxillofacial Radiology –, Oral Radiology, 10.1007/s11282-018-0353-9, 35, 2, 101-126, 2018.11, Sonography is a simple, inexpensive, and non-invasive diagnostic modality. Although tissues behind bony structures and deep
tissues are not delineated, sonography can depict superficial soft tissues very clearly. In the head and neck region, however,
it has not yet been used widely, as the anatomical structures are complicated, and considerable experience is needed both to
perform an examination and to make a diagnosis. To perform examinations efficiently, operators must be familiar with the
sonographic system in use, and take images at standard planes. To make a correct diagnosis, operators require knowledge
of the sonographic anatomy on standard planes, representative sonographic signs and artifacts, and common diseases and
their typical sonographic findings. In this paper, we have explained the sonographic anatomy on standard planes, and the
sonographic findings of common diseases in the oral and maxillofacial region.. |
| 6. |
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, 2018.09, Objectives: To find the optimum cone beam CT 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. The image quality of anatomical structures: dentin-enamel junction (1), lamina dura
and periodontal ligament (PDL) space (2), trabecular pattern (3), cortex-spongy bone
junction (4) and pulp chamber and root canal (5) was evaluated by observers, and the
diagnostic image quality was analyzed 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 an acceptable diagnostic image quality level.
Results: For small container, the optimum exposure parameters were D mode, 80 kV
for 1, 3 and 4 and D mode, 100 kV for 5. For large containers, 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 acceptable level for 2.
Conclusions: There were no optimum exposure parameters for evaluation of lamina
dura and PDL space. D mode was sufficient for the other structures; however, the tube
voltage required for each structure was different. Smaller patients required lower tube
voltage. I mode, 120 kV may be used for larger lesions.. |
| 7. |
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, https://doi.org/10.1007/s11282-018-0325-0, 35, 3, 59-67, 2018.04, 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 obtained in 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.
Materials and Methods: CBCT images of a Teflon plate phantom with holes of decreasing depths from 0.7–0.1 mm were analysed using the FindFoci plugin of ImageJ. Subsequently, we constructed cluster signal-to-noise curves by plotting TPRs against false-positive rates (FPRs). The four parameters were assessed in the correlation with diagnostic accuracy obtained from observers. To analyse 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 evaluated their correlations with diagnostic accuracy obtained from observers.
Results: Accuracy corresponding to background noise had the highest correlation with the diagnostic accuracy among the four representative parameters. Regarding the ranges of hole depths, 0.3–0.7 and 0.1–0.7 mm had the highest correlation with diagnostic accuracy in the 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.. |
| 8. |
Yohei Takeshita, Mayumi Shimizu, Gainer Raul 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, in press, 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 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 mandibular canal.
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 mandibular canal 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 mandibular canal in CBCT images.
. |
| 9. |
Warangkana Weerawanich, Mayumi Shimizu, Kazutoshi Okamura, Shoko Yoshida, Kazunori Yoshiura, Cluster signal-to-noise analysis for evaluation of the information content in an image, Dentomaxillofacial Radiology, in press, 2017.10, Objectives: 1) To develop an observer-free method of analyzing image quality related to the observer performance in the detection task and 2) to analyze observer behavior patterns in the detection of small mass changes in CBCT images. Materials and Methods: Thirteen observers detected holes in a Teflon phantom in CBCT images. Using the same images, we developed a new method, cluster signal-tonoise analysis, to detect the holes by applying various cut-off values using ImageJ and reconstructing cluster signal-to-noise 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 inter-observer 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 inter-observer variations. TPRs and accuracies calculated from background noise had high correlation with actual TPRs from observers; R² was 0.9244 and 0.9338, respectively. Conclusion: 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.. |
| 10. |
Yohei Takeshita, Mayumi Shimizu, Kazutoshi Okamura, Shoko Yoshida, Warangkana Weerawanich, Kenji Tokumori, Gainer Raul Jasa, Kazunori Yoshiura, A new method to evaluate image quality of CBCT images quantitatively without observers, Dentomaxillofacial Radiology, in press, 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 aluminum step phantom. These phantoms had holes with different depths. They were immersed in water and scanned with a CB MercuRay at tube voltages of 120, 100, 80, 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 gray value (ΔG) which differentiated holes from the background was calculated using a specific threshold (the JND), and we extracted the holes with gray values above ΔG. The indexes obtained by this quantitative method (the extracted hole values) were compared with the observers’ 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.. |
| 11. |
Gainer Raul Jasa, Mayumi Shimizu, Kazutoshi Okamura, Kenji Tokumori, Yohei Takeshita, Warangkana Weerawanich, Kazunori Yoshiura, Effects of exposure parameters and slice thickness on detecting clear and unclear mandibular canals using cone beam CT, Dentomaxillofacial Radiology, in press, 2017.03, Objectives The purpose of this study was to clarify the effects of exposure parameters and image processing methods when using cone beam CT (CBCT) to detect clear and unclear mandibular canals (MCs).
Methods Twenty-four dry half mandibles were divided into two groups with clear and unclear MCs based on a previous CBCT study. Mandibles were scanned using a CBCT system with varying exposure parameters (tube voltages 60, 70, and 90 kV; and tube currents 2, 5, 10 and 15 mA) to obtain a total of 144 scans. The images were processed with different slice thicknesses using ImageJ software. Five radiologists evaluated the cross-sectional images of the first molar region to detect the MCs. The diagnostic accuracy of varying exposure parameters and image processing conditions was compared with areas under the curves (Az) in receiver operating characteristic (ROC) analysis.
Results: The Az values for clear MCs were higher than those for unclear MCs. With increasing exposure voltages and currents, Az values increased, but no significant differences were found with high voltages and currents in clear MCs (p = 0.6825 and p = 0.7156). The Az values of serial images were higher than those of overlaid images (p < 0.0001), and those for thicker slices were higher than those for thinner slices (p < 0.0001).
Conclusions: Our findings indicate that detection of unclear MCs requires either higher exposure parameters or processing of the images with thicker slices. To detect clear MCs, lower exposure parameters can be used.. |
| 12. |
Mayumi Shimizu, Kazutoshi Okamura, Yoshitaka Kise, Yohei Takeshita, Hiroko Furuhashi, Warangkana Weerawanich, Moriyama Masafumi, Yukiko Ohyama, Furukawa Sachiko, Seiji Nakamura, Kazunori Yoshiura, 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., Arthritis Research & Therapy, 10.1186/s13075-015-0751-x, 17, 233, 2015.08, Introduction: The aim of this study was to clarify the effectiveness of various imaging modalities and characteristic imaging features in the screening of IgG4-related dacryoadenitis and sialadenitis (IgG4-DS), and to show the differences in the imaging features between IgG4-DS and Sjögren’s syndrome (SS).
Methods: Thirty-nine patients with IgG4-DS, 51 with SS and 36 with normal salivary glands were enrolled. Images of the parotid and submandibular glands obtained using sonography, 2-[18F]-fluoro-2-deoxy-D-glucose positron emission tomography/computed tomography (FDG-PET/CT), computed tomography (CT) and magnetic resonance imaging (MRI) were retrospectively analyzed. Six oral and maxillofacial radiologists randomly reviewed the arranged image sets under blinded conditions. Each observer scored the confidence rating regarding the presence of the characteristic imaging findings using a 5-grade rating system. After scoring various findings, diagnosis was made as normal, IgG4-DS or SS, considering all findings for each case.
Results: On sonography, multiple hypoechoic areas and hyperechoic lines and/or spots in the parotid glands and obscuration of submandibular gland configuration were detected mainly in patients with SS (median scores 4, 4 and 3, respectively). Reticular and nodal patterns were observed primarily in patients with IgG4-DS (median score 5). FDG-PET/CT revealed a tendency for abnormal 18F-FDG accumulation and swelling of both the parotid and submandibular glands in patients with IgG4-DS, particularly in the submandibular glands. On MRI, SS had a high score regarding the findings of a salt-and-pepper appearance and/or multiple cystic areas in the parotid glands (median score 4.5). Sonography showed the highest values among the four imaging modalities for sensitivity, specificity and accuracy. There were significant differences between sonography and CT (p = 0.0001) and between sonography and FDG-PET/CT (p = 0.0058) concerning accuracy.
Conclusions: Changes in the submandibular glands affected by IgG4-DS could be easily detected using sonography (characteristic bilateral nodal/reticular change) and FDG-PET/CT (abnormal 18F-FDG accumulation). Even inexperienced observers could detect these findings. In addition, sonography could also differentiate SS. Consequently, we recommend sonography as a modality for the screening of IgG4-DS, because it is easy to use, involves no radiation exposure and is an effective imaging modality.. |
| 13. |
Moriyama Masafumi, Tanaka A, Maehara T, YUKIKO OHYAMA, Mayumi Shimizu, Nakashima H, Hayashida Jun-Nosuke, Shinozaki S, Kubo Y, Furukawa S, Kikuta T, Seiji Nakamura, Clinical characteristics of Mikulicz's disease as an IgG4-related disease., Clin Oral Invest, 10.1007/s00784-012-0905-z, 2013.05. |
| 14. |
Shimizu M, Moriyama M, Okamura K, Kawazu T, Chikui T, Goto TK, Ohyama Y, Nakamura S, Yoshiura K., Sonographic diagnosis for Mikulicz disease, Oral Surg Oral Med Oral Pathol Oral Radiol Endod, 108：105-113, 2009.07. |
| 15. |
Mayumi Shimizu, Ussmuller J, Hartwein J, Donath K. , A comparative study of sonographic and histopathologic findings of tumorous lesions in the parotid gland, Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology, 88, 6, 723-737, 1999.12, Objective. The purpose of this study was to clarify characteristic sonomorphologic features of parotid lesions statistically and to propose new criteria for the differential diagnosis. Study design. Eighty-six tumorous lesions were analyzed with regard to the following sonomorphologic features: boundary, shape, echo intensity level, distribution of internal echoes, and acoustic enhancement. Stepwise polychotomous logistic regression analysis was performed to assess characteristic sonographic features. As dependent variables, we used "pleomorphic adenoma," "Warthin tumor," "malignant tumors" and "other benign lesions"; as predictor variables, we used the aforementioned sonomorphologic features. Proportion of the occurrence of each dependent variable was calculated. Results. Lobular shape and homogeneous internal echoes predicted pleomorphic adenoma. A lesion with multiple anechoic areas would be Warthin tumor with very high sensitivity. Malignant tumors showed either heterogeneous internal echoes without characteristic structures or polygonal shape. Conclusions. These sonomorphologic features should be observed to make more exact differential diagnoses for operation and therapy planning.. |
| 16. |
Mayumi Shimizu, Ussmuller J, Hartwein J, Donath K, Kinukawa N., Statistical study for sonographic differential diagnosis of tumorous lesions in the parotid gland, Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology, 10.1016/S1079-2104(99)70120-4, 88, 2, 226-233, 1999.01, Objective. The purpose of this study was to clarify characteristic sonomorphologic features of parotid lesions statistically and to propose new criteria for the differential diagnosis. Study design. Eighty-six tumorous lesions were analyzed with regard to the following sonomorphologic features: boundary, shape, echo intensity level, distribution of internal echoes, and acoustic enhancement. Stepwise polychotomous logistic regression analysis was performed to assess characteristic sonographic features. As dependent variables, we used "pleomorphic adenoma," "Warthin tumor," "malignant tumors" and "other benign lesions"; as predictor variables, we used the aforementioned sonomorphologic features. Proportion of the occurrence of each dependent variable was calculated. Results. Lobular shape and homogeneous internal echoes predicted pleomorphic adenoma. A lesion with multiple anechoic areas would be Warthin tumor with very high sensitivity. Malignant tumors showed either heterogeneous internal echoes without characteristic structures or polygonal shape. Conclusions. These sonomorphologic features should be observed to make more exact differential diagnoses for operation and therapy planning.. |
