Faculty Profiles - TAKESHITA Yohei

Papers - TAKESHITA Yohei

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A Case of Odontogenic Myxoma of the Mandible with Expansion to the Alveolar Crest - Comparison of Imaging Findings and Pathological Findings: A Case Report Reviewed

Saori Yoshida, Yohei Takeshita, Toshiyuki Kawazu, Tatsushi Matsumura, Junichi Asaumi, Hitoshi Nagatsuka, Yoshinobu Yanagi

OPEN DENTISTRY JOURNAL 16 2022

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：BENTHAM SCIENCE PUBL LTD

Background:An odontogenic myxoma is an intraosseous tumor characterized by stellate and spindle-shaped cells embedded in an abundant myxoid or mucoid extracellular matrix. We herein describe an odontogenic myxoma that expanded not only to the bone marrow but also to the outside of the alveolar bone. Diagnosis of an odontogenic myxoma in a tooth-deficient region by imaging findings alone was difficult because the positional relationship between the tumor and the tooth is unknown. Furthermore, some of these odontogenic myxomas reportedly show rapid growth.Case Report:Here, we present the case of a patient, a 44-year-old man, who had a hard, bone-like swelling on his right mandible molar region and mild paresthesia on his right cheek. An odontogenic myxoma and ameloblastoma were suspected based on the imaging findings; however, pathological examination of the biopsy led to a diagnosis of odontogenic myxoma. Right segmental mandibulectomy was performed, and there was no recurrence observed after surgery.Conclusion:To improve the accuracy of imaging diagnosis, it is important to compare the imaging findings with the pathological findings of the surgical specimen. This comparison in the present case revealed differences in the magnetic resonance imaging signal intensity in regions with different types of cell components.

DOI： 10.2174/18742106-v16-2202140

What are the retromolar and bifid/trifid mandibular canals as seen on cone-beam computed tomography? Revisiting classic gross anatomy of the inferior alveolar nerve and correcting terminology. Reviewed International journal

Joe Iwanaga, Yohei Takeshita, Yuki Matsushita, Mi-Sun Hur, Soichiro Ibaragi, R Shane Tubbs

Surgical and radiologic anatomy : SRA 44 ( 1 ) 147 - 156 2021.12

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

PURPOSE: Since cone-beam computed tomography was developed, a number of radiological studies on the bifid mandibular canals (BMCs) and trifid mandibular canals (TMCs) have been reported. However, many of the suggested subtypes of the BMC described in the literature seem to be normal branches of the inferior alveolar nerve. This might be due to a lack of revisiting classic anatomical studies in the field of radiology. Therefore, such studies are revisited here. METHODS: A database search using PubMed and Google Scholar was conducted on BMC and TMC. Eighty-nine articles underwent full-text assessment. The reported three classifications of BMC and the six modified classifications were reviewed and compared to the intramandibular inferior alveolar nerve branches. RESULTS: Some subtypes of BMC and TMC simply represent normal inferior alveolar nerve branches, i.e., retromolar branch, molar branch (alveolar branch/dental branch), large mental branch, or communicating branch. Others such as Naitoh's type III BMC and forward canal might be a true BMC. CONCLUSION: We found that the bifid mandibular canal is an additional intramandibular canal running parallel to the mandibular canal with/without confluence with the main canal through comparison of classifications of BMC/TMC between the radiology and anatomy fields.

DOI： 10.1007/s00276-021-02862-y

Dynamic contrast-enhanced MRI as a predictor of programmed death ligand-1 expression in patients with oral squamous cell carcinoma Reviewed

Nouha Tekiki, Mariko Fujita, Tatsuo Okui, Hotaka Kawai, May Oo, Toshiyuki Kawazu, Miki Hisatomi, Shunsuke Okada, Yohei Takeshita, Majd Barham, Hitoshi Nagatsuka, Yoshinobu Yanagi, Jun-Ichi Asaumi

ONCOLOGY LETTERS 22 ( 5 ) 2021.11

Language：English Publishing type：Research paper (scientific journal) Publisher：SPANDIDOS PUBL LTD

Immune checkpoint inhibitors (ICIs) targeting programmed death ligand-1 (PD-L1) are highly promising therapies for oral squamous cell carcinoma (OSCC). The assessment of PD-L1 expression may help predicting the therapeutic effect of ICIs and, thus, benefit patient selection. Contrast index (CI) parameters derived from dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) have been proven as efficient to assess microvessel density (MVD) in OSCC. The present study aimed to determine the correlation between DCE-MRI parameters and MVD and between DCE-MRI parameters and PD-L1 expression to determine whether DCE-MRI could be used non-invasively to evaluate PD-L1 expression in patients with OSCC. A total of 21 patients with primary OSCC who had undergone a 3T MRI scan, including DCE-MRI, were included in the present study, and CI curve-derived parameters were examined. The MVD and PD-L1 expression in the surgically resected specimens were analyzed using immunohistochemistry (IHC) staining for CD31 and IHC staining for PD-L1, respectively. The results demonstrated that the expression levels of these markers were correlated with DCE-MRI parameters. PD-L1 expression levels were found to be significantly correlated with the maximum CI (CI-max; P=0.007), peak CI (CI-peak; P=0.007), maximum CI gain (CI-gain; P=0.006) and MVD (P=0.001) values. The mean CI-max, CI-peak, CI-gain and MVD values were significantly higher in tumors with high PD-L1 expression (P<0.05). MVD levels were also significantly correlated with the time of CI-max (T-max; P=0.003) and CI-gain (P=0.037). The mean CI-gain was significantly increased, and the mean T-max was significantly shorter in high MVD tumors (P<0.05 and P<0.01, respectively). In summary, the findings from the present study confirmed the correlation between CI parameters, derived from DCE-MRI, and MVD, and suggested that these parameters may be correlated with PD-L1 expression in OSCC tumor cells.

DOI： 10.3892/ol.2021.13039

Displacement of lower third molar into floor of mouth: a single institutional experience Reviewed International journal

Masanori Masui, Soichiro Ibaragi, Yohei Takeshita, Joe Iwanaga, Yuki Kunisada, Akira Sasaki

Oral and Maxillofacial Surgery 26 ( 3 ) 447 - 453 2021.10

Language：English Publishing type：Research paper (scientific journal) Publisher：Springer Science and Business Media LLC

PURPOSE: The displacement of the tooth/tooth fragment into the floor of mouth sometimes happens during the lower third molar surgery and the patients are usually referred to oral and maxillofacial surgeons. To date, however, there is no consensus how to manage the displaced tooth due to the lack of available data. METHODS: In this study, we have retrospectively analyzed the management of the displaced lower third molar into the floor of mouth. Our institute experienced seven cases during 2010 to 2020. RESULTS: Incidence rate of the lingual nerve injury caused by displacement of the lower third molar was 1/7. Six patients out of seven underwent surgical removal of the displaced fragment. The direct approach was used when the fragment was palpable superficially and the fragment was horizontally located away from the lingual plate (2 cases), while when the fragment was not palpable, or was palpable and adjacent to the lingual plate, the lingual mucoperiosteal flap was selected (4 cases). CONCLUSION: We conclude that the palpation and preoperative diagnosis with computed tomographic images are significantly important to decide a better and most effective surgical approach.

DOI： 10.1007/s10006-021-01012-3

Other Link： https://link.springer.com/article/10.1007/s10006-021-01012-3/fulltext.html

The potential for facial artery injury during mandibular third molar extraction. An anatomical study using contrast-enhanced computed tomography. Reviewed International journal

Yohei Takeshita, Soichiro Ibaragi, Hirokazu Yutori, Jingo Kusukawa, R Shane Tubbs, Toshiyuki Kawazu, Junichi Asaumi, Joe Iwanaga

Clinical anatomy (New York, N.Y.) 34 ( 8 ) 1215 - 1223 2021.8

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal)

The purpose of this study was to evaluate the risk of injury to the facial (FA) and related arteries during mandibular third molar (MTM) extraction using contrast-enhanced computed tomography (CE-CT). CE-CT images of the MTM region were retrospectively reviewed. The area of the MTM was equally divided into three zones in the coronal images from mesial to distal, that is, zone 1, zone 2, and zone 3. The FA, submental artery (SMA), and sublingual artery (SLA) were identified. The distance from the mandible to FA, SMA, and SLA and the diameter of the FA, SMA, and SLA was measured in three zones, respectively. The thickness of the facial soft tissues and width of the mandible were measured at their maximum. The mean distance from the FA to the buccal cortical bone in zone 1, zone 2 and zone 3 was 2.24 mm, 2.39 mm and 1.67 mm, respectively. The SMA and SLA were found to be distal to the mandible. The mean diameter of the FA was 1.26 mm in males and 1.04 mm in females, respectively (p < 0.0001). The distance between the FA and buccal cortical bone of the mandible, and the patients' weight showed moderate correlation in zones 1 and 2. Based on our findings, the FA can be damaged if the surgical invasion reaches the facial soft tissues during MTM surgery. The patients' weight might be a good predictor for FA injury when CE-CT is not available.

DOI： 10.1002/ca.23779

Mandibular canal versus inferior alveolar canal: A Delphi study. Reviewed International journal

Joe Iwanaga, Soichiro Ibaragi, Yohei Takeshita, Junichi Asaumi, Keith Horner, Thomas R Gest, R Shane Tubbs

Clinical anatomy (New York, N.Y.) 34 ( 7 ) 1095 - 1100 2021.4

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

The general principles of anatomical terminology indicate that the "mandibular canal" should be named the "inferior alveolar canal" as it accommodates the inferior alveolar neurovascular bundles. Therefore, we performed a Delphi study to evaluate the current understanding and use of the terminology in different geographical regions and areas of expertise and to determine the appropriate terminology for this bony canal. A Delphi panel was formed and questions sent and answered via email about: field of expertise (anatomy, oral surgery/oral and maxillofacial (OMF) surgery, oral radiology/OMF radiology, plastic surgery, ENT surgery, or dentistry with the exception of oral/OMF surgery and oral/OMF radiology), years of experience in the field of expertise, country currently working in, "what is the name of the bony canal that contains the inferior alveolar neurovascular bundle," and "what should the structure above be called, in general?" A total of 52 participants responded to the questionnaire. Half or more of the experts in anatomy, oral/OMF surgery, and ENT/plastic surgery considered "mandibular canal" to be the most appropriate name for this bony canal. In contrast, more than half of all experts in oral/OMF radiology and dentistry, that is, most fields of dentistry, considered "either mandibular canal or inferior alveolar canal" to be the appropriate name. The results of the Delphi study and general principles suggest that an alternative term for the "mandibular canal" should be "inferior alveolar canal."

DOI： 10.1002/ca.23740

Comprehensive review of lower third molar management: A guide for improved informed consent. Reviewed International journal

Joe Iwanaga, Yuki Kunisada, Masanori Masui, Kyoichi Obata, Yohei Takeshita, Kotaro Sato, Shogo Kikuta, Yushi Abe, Yuki Matsushita, Jingo Kusukawa, R Shane Tubbs, Soichiro Ibaragi

Clinical anatomy (New York, N.Y.) 34 ( 2 ) 224 - 243 2021.3

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

Lower third molar removal is the most commonly performed dental surgical procedure. Nevertheless, it is difficult to ensure that all the informed consent forms given to patients are based on the best evidence as many newer publications could change the conclusions of previous research. Therefore, the goal of this review article is to cover existing meta-analyses, randomized control trials, and related articles in order to collect data for improved and more current informed consent.

DOI： 10.1002/ca.23693

Assessment of Hounsfield unit in the differential diagnosis of odontogenic cysts. Reviewed International journal

Kyonori Uehara, Miki Hisatomi, Luciana Munhoz, Toshiyuki Kawazu, Yoshinobu Yanagi, Shunsuke Okada, Yohei Takeshita, Emiko Arita Saito, Junichi Asaumi

Dento maxillo facial radiology 50 ( 2 ) 20200188 - 20200188 2021.2

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

OBJECTIVES: The purpose of this study was to evaluate the usefulness of Hounsfield unit (HU) assessment with multislice-CT in the differentiation of radicular cysts (RCs), dentigerous cysts (DCs) and odontogenic keratocysts (OKCs). METHODS: In total, 307 odontogenic cysts (RCs, DCs and OKCs) were included in this study. Cysts with lesion diameter <10 mm, cysts with artefacts affecting measurement of HU values, cysts involving infection and recurrent cysts were regarded as exclusion criteria. Images were acquired in three different types of CT scanners: Aquilion ONE, Discovery CT750 HD and SOMATOM Definition Flash. Differences in HU values among scanners and among types of odontogenic cysts were assessed using one-way analysis of variance; multiple comparisons were performed post hoc, using the Tukey-Kramer honestly significant difference test. RESULTS: In total, 164 cysts were analysed in this study (64 RCs, 57 DCs and 43 OKCs). Regardless of the type of lesion, the Aquilion ONE scanner demonstrated a significant difference in HU value, compared with the Discovery CT750 HD scanner. Regardless of CT scanner model, HU values significantly differed between DCs and OKCs (p < 0.0001), as well as between OKCs and RCs (p < 0.0001). CONCLUSIONS: HU values were found to vary among CT scanners and should always be associated with other lesion imaging features while interpreting and elaboration diagnostic hypothesis. Notably, the results suggested that OKCs might be able to be differentiated from DCs and RCs by using HU values.

DOI： 10.1259/dmfr.20200188

No convincing evidence for the presence of tubarial salivary glands: A letter to the editor regarding "The tubarial salivary glands: A potential new organ at risk for radiotherapy". Reviewed International journal

Joe Iwanaga, Soichiro Ibaragi, Keisuke Nakano, Yohei Takeshita, R Shane Tubbs

Radiotherapy and oncology : journal of the European Society for Therapeutic Radiology and Oncology 154 321 - 322 2021.1

Incidental findings in the thyroid gland on computed tomography images of the oral and maxillofacial region. Reviewed International journal

Abdullah Khasawneh, Yohei Takeshita, Miki Hisatomi, Toshiyuki Kawazu, Mariko Fujita, Shunsuke Okada, Yuri Namba, Yudai Shimizu, Yoshinobu Yanagi, Junichi Asaumi

Oncology letters 19 ( 3 ) 2005 - 2010 2020.3

Authorship：Corresponding author Language：English Publishing type：Research paper (scientific journal)

The numbers of abnormal findings incidentally detected in adjacent regions are increasing with advances in imaging modalities. The present study aimed to examine the prevalence and characteristics of incidental findings in the thyroid gland on computed tomography (CT) images of the oral and maxillofacial region. CT scans of the oral and maxillofacial region in patients obtained between January 2012 and December 2016 were retrospectively reviewed. Images that revealed incidental findings in the thyroid gland, including nodules, were recorded, together with the sizes and characteristics of the findings. The Japan Association of Breast and Thyroid Sonology (JABTS) guidelines were used for classification. The rate of descriptions of these findings in the radiographic interpretation reports were also examined. Of the 1,135 patients examined, 326 (28.7%) had several types of incidental findings. In particular, 169 (14.9%) of the 1,135 patients had nodules >5 mm in diameter, for which further careful examination is recommended in the JABTS guideline. The description rate for nodules >5 mm in diameter in the radiographic interpretation reports was 30.8% (52/169 patients), of whom 17.3% (9/52 patients) were referred to the endocrinology department for further careful examination. Incidental findings in the thyroid gland were relatively common on CT images of the oral and maxillofacial region. Oral radiologists tend to focus specifically on the oral and maxillofacial region during diagnosis on oral and maxillofacial CT images, but should pay the same careful attention to observe adjacent regions, such as the thyroid gland.

DOI： 10.3892/ol.2020.11298

Oropharyngeal adenoid cystic carcinoma invading the mandibular bone through the mandibular foramen. Reviewed

Yohei Takeshita, Shunsuke Okada, Miki Hisatomi, Hidenobu Matsuzaki, Hotaka Kawai, Yohei Noda, Jun Murakami, Mariko Fujita, Hitoshi Nagatsuka, Yoshinobu Yanagi, Junichi Asaumi

Oral radiology 35 ( 3 ) 335 - 340 2019.9

Authorship：Lead author Language：English Publishing type：Research paper (scientific journal) Publisher：SPRINGER

Adenoid cystic carcinoma (ACC) is a rare epithelial tumor of the head and neck region, and one of the most common malignant tumors of the salivary glands. ACC is a slow-growing tumor characterized by perineural invasion and often has a high-recurrence rate. We describe a case of oropharyngeal ACC invading the mandibular bone through the mandibular foramen that showed a rare pattern of origin and invasion. A 70-year-old woman complained of noise and pain around the right temporomandibular joint. Osteomyelitis was suspected on the initial imaging examinations, although the findings were slightly atypical. However, a mass was observed in the right oropharyngeal wall on subsequent imaging examinations, and mandibular bone invasion, rather than osteomyelitis, was additionally suspected. The mass in the right oropharyngeal wall and right mandible was surgically excised. On postoperative histopathological examination, the mass was finally diagnosed as ACC. As tumor cells were also observed around the inferior alveolar nerve, mandibular bone invasion through the mandibular foramen was suspected. An oropharyngeal ACC invading the mandibular bone through the mandibular foramen is extremely rare. The present case suggests that bone invasion should be considered carefully with several imaging examinations when a malignant tumor such as ACC is observed around the jaw bone.

DOI： 10.1007/s11282-018-0359-3

Determination of optimum exposure parameters for dentoalveolar structures of the jaws using the CB MercuRay system with cluster signal-to-noise analysis. Reviewed

Warangkana Weerawanich, Mayumi Shimizu, Yohei Takeshita, Kazutoshi Okamura, Shoko Yoshida, Gainer R Jasa, Kazunori Yoshiura

Oral radiology 35 ( 3 ) 260 - 271 2019.9

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

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.

DOI： 10.1007/s11282-018-0348-6

Fourth molar: A retrospective study and literature review of a rare clinical entity. Reviewed International journal

Babatunde O Bamgbose, Shunsuke Okada, Miki Hisatomi, Yoshinobu Yanagi, Yohei Takeshita, Zahrau Saleh Abdu, Edugie J Ekuase, Jun-Ichi Asaumi

Imaging science in dentistry 49 ( 1 ) 27 - 34 2019.3

Language：English Publishing type：Research paper (scientific journal) Publisher：KOREAN ACAD ORAL & MAXILLOFACIAL RADIOLOGY

Purpose: The prevalence of supernumerary teeth has been reported to be between 0.1% and 3.8%. The aim of this study was to determine the prevalence, clinical significance, and associated pathologies of fourth molars based on a retrospective study and a literature review. Materials and Methods: A 5-year retrospective prevalence study was conducted at the Department of Oral Diagnosis and Dentomaxillofacial Radiology of Okayama University Hospital, Okayama, Japan. The study involved extracting data from the digital records of patients from January 1, 2013 through December 31, 2017. The sampling frame included all patients who had panoramic radiographs, cone-beam computed tomography (CT), and multislice CT images during the period under review. Results: A total of 26,721 cases were reviewed and 87 fourth molars were identified. The prevalence of fourth molars in the 5-year study at Okayama was calculated as 0.32%. The mean age of patients with a fourth molar was 30.43 years, and the male-to-female ratio was 1:0.98. The vast majority of cases were in the maxilla (92%) and had normal shapes (89.7%); furthermore, 82.8% of cases were unerupted. Conclusion: The prevalence of fourth molars in the study population was found to be 0.32%, and fourth molars occurred with approximately equal frequency in males and females. Fourth molars were more common in the maxilla and were predominantly unerupted and small.

DOI： 10.5624/isd.2019.49.1.27

Evaluation of cone-beam computed tomography diagnostic image quality using cluster signal-to-noise analysis. Reviewed

Warangkana Weerawanich, Mayumi Shimizu, Yohei Takeshita, Kazutoshi Okamura, Shoko Yoshida, Gainer R Jasa, Kazunori Yoshiura

Oral radiology 35 ( 1 ) 59 - 67 2019.1

Language：English Publishing type：Research paper (scientific journal) Publisher：Springer Tokyo

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.

DOI： 10.1007/s11282-018-0325-0

Prediction of detectability of the mandibular canal by quantitative image quality evaluation using cone beam CT. Reviewed International journal

Yohei Takeshita, Mayumi Shimizu, Gainer R Jasa, Warangkana Weerawanich, Kazutoshi Okamura, Shoko Yoshida, Kenji Tokumori, Junichi Asaumi, Kazunori Yoshiura

Dento maxillo facial radiology 47 ( 4 ) 20170369 - 20170369 2018.5

Authorship：Lead author,　Corresponding author Language：English Publishing type：Research paper (scientific journal) Publisher：British Institute of Radiology

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.

DOI： 10.1259/dmfr.20170369

Cluster signal-to-noise analysis for evaluation of the information content in an image. Reviewed International journal

Warangkana Weerawanich, Mayumi Shimizu, Yohei Takeshita, Kazutoshi Okamura, Shoko Yoshida, Kazunori Yoshiura

Dento maxillo facial radiology 47 ( 1 ) 20170147 - 20170147 2018.1

Language：English Publishing type：Research paper (scientific journal) Publisher：British Institute of Radiology

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-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 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.

DOI： 10.1259/dmfr.20170147

A Case of Schwannoma of the Submandibular Region. Reviewed International journal

Babatunde O Bamgbose, Akiko Sato, Yoshinobu Yanagi, Miki Hisatomi, Yohei Takeshita, Irfan Sugianto, Junichi Asaumi

The open dentistry journal 12 12 - 18 2018

Language：English Publishing type：Research paper (scientific journal) Publisher：Bentham Science Publishers B.V.

Background: We herein described a rare case of schwannoma of the hypoglossal nerve in the submandibular region with diagnostic imaging and histopathological findings. Case Report: A 31-years-old woman has had a palpable firm, rubbery, freely mobile mass in the submandibular region. Of imaging, MR images showed homogeneous isointensity on T1-weighted imaging (T1-WI), heterogeneous hypointensity on T2-WI, heterogeneous hyperintensity on short T1 inversion recovery (STIR), and heterogeneous enhancement on contrast-enhanced T1-WI. A clear capsule was observed on the margin and showed hypointense on T2-WI. Dynamic MRI showed heterogeneous gradual increased enhancement. The uptake of contrast medium was regionally slow. Diagnostic imaging using CT and MRI was suspected of salivary gland tumor or neurogenic tumor. In consideration of imaging diagnosis, a pleomorphic adenoma or a schwannoma was suspected. Final diagnosis was confirmed on the basis of histopathological finding and intraoperative findings. Conclusion: 1. Histopathologic examination is inevitable, because MR findings are not specific.2. Schwannomas were said to have specific MRI properties, including specific signs (split-fat sign, fascicular sign, target sign). However, they are not always observed.3. This case confirmed the differential diagnosis on the basis of the intraoperative finding that the tumor was continuous with the hypoglossal nerve.

DOI： 10.2174/1874210601812010012

ファントムおよび輝度弁別閾を用いたMDCTにおける硬組織最適撮影条件決定法 Reviewed

岡村和俊, 吉田祥子, 徳森謙二, 清水真弓, 竹下洋平, Warangkana Weerawanich, 吉浦一紀

歯科放射線 58 ( 2 ) 58 - 65 2018

Diagnostic Value of Fluid-Attenuated Inversion Recovery Magnetic Resonance Imaging for Multilocular Ameloblastoma Reviewed

Irfan Sugianto, Hironobu Konouchi, Yohei Takeshita, Shunsuke Okada, Risa Matsubara, Miki Hisatomi, Jun Murakami, Babatunde O. Bamgbose, Yoshinobu Yanagi, Junichi Asaumi

Journal of Hard Tissue Biology 27 ( 4 ) 275 - 280 2018

Effects of exposure parameters and slice thickness on detecting clear and unclear mandibular canals using cone beam CT. Reviewed International journal

Gainer R Jasa, Mayumi Shimizu, Kazutoshi Okamura, Kenji Tokumori, Yohei Takeshita, Warangkana Weerawanich, Kazunori Yoshiura

Dento maxillo facial radiology 46 ( 4 ) 20160315 - 20160315 2017.4

Language：English Publishing type：Research paper (scientific journal) Publisher：BRITISH INST RADIOLOGY

OBJECTIVES: The purpose of this study was to clarify the effects of exposure parameters and image-processing methods when using CBCT to detect clear and unclear mandibular canals (MCs). METHODS: 24 dry half mandibles were divided into 2 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 kV, 70 kV and 90 kV; and tube currents 2 mA, 5 mA, 10 mA and 15 mA) to obtain a total of 144 scans. The images were processed with different slice thicknesses using ImageJ software (National Institutes of Health, Bethesda, MD). 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 the area under the curve (Az) in receiver-operating characteristic analysis. RESULTS: The Az values for clear MCs were higher than those for unclear MCs (p < 0.0001). With increasing exposure voltages and currents, Az values increased, but no significant differences were found with high voltages and currents in clear MCs (p = 1.0000 and p = 0.9340). 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.

DOI： 10.1259/dmfr.20160315

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