• Imaging Science in Dentistry
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• 제52권4호
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• pp.383-391
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• 2022

Purpose: Periodontitis, the most prevalent chronic inflammatory condition affecting teeth-supporting tissues, is diagnosed and classified through clinical and radiographic examinations. The staging of periodontitis using panoramic radiographs provides information for designing computer-assisted diagnostic systems. Performing image segmentation in periodontitis is required for image processing in diagnostic applications. This study evaluated image segmentation for periodontitis staging based on deep learning approaches. Materials and Methods: Multi-Label U-Net and Mask R-CNN models were compared for image segmentation to detect periodontitis using 100 digital panoramic radiographs. Normal conditions and 4 stages of periodontitis were annotated on these panoramic radiographs. A total of 1100 original and augmented images were then randomly divided into a training (75%) dataset to produce segmentation models and a testing (25%) dataset to determine the evaluation metrics of the segmentation models. Results: The performance of the segmentation models against the radiographic diagnosis of periodontitis conducted by a dentist was described by evaluation metrics(i.e., dice coefficient and intersection-over-union [IoU] score). MultiLabel U-Net achieved a dice coefficient of 0.96 and an IoU score of 0.97. Meanwhile, Mask R-CNN attained a dice coefficient of 0.87 and an IoU score of 0.74. U-Net showed the characteristic of semantic segmentation, and Mask R-CNN performed instance segmentation with accuracy, precision, recall, and F1-score values of 95%, 85.6%, 88.2%, and 86.6%, respectively. Conclusion: Multi-Label U-Net produced superior image segmentation to that of Mask R-CNN. The authors recommend integrating it with other techniques to develop hybrid models for automatic periodontitis detection.

• The Journal of Advanced Prosthodontics
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• 제15권6호
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• pp.315-332
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• 2023

PURPOSE. This study aimed to investigate whether the accuracy of intraoral scanners is influenced by different scanning strategies in an in vitro setting, through a systematic review and meta-analysis. MATERIALS AND METHODS. This review was conducted in accordance with the PRISMA 2020 standard. The following PICOS approach was used: population, tooth impressions; intervention, the use of intraoral scanners with scanning strategies different from the manufacturer's instructions; control, the use of intraoral scanners following the manufacturers' requirements; outcome, accuracy of intraoral scanners; type of studies, in vitro. A comprehensive literature search was conducted across various databases including Embase, SciELO, PubMed, Scopus, and Web of Science. The inclusion criteria were based on in vitro studies that reported the accuracy of digital impressions using intraoral scanners. Analysis was performed using Review Manager software (version 5.3.5; Cochrane Collaboration, Copenhagen, Denmark). Global comparisons were made using a standardized mean difference based on random-effect models, with a significance level of α = 0.05. RESULTS. The meta-analysis included 15 articles. Digital impression accuracy significantly improved under dry conditions (P < 0.001). Moreover, trueness and precision were enhanced when artificial landmarks were used (P ≤ 0.02) and when an S-shaped pattern was followed (P ≤ 0.01). However, the type of light used did not have a significant impact on the accuracy of the digital intraoral scanners (P ≥ 0.16). CONCLUSION. The accuracy of digital intraoral scanners can be enhanced by employing scanning processes using artificial landmarks and digital impressions under dry conditions.

• 대한두개안면성형외과학회지
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• 제21권1호
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• pp.64-68
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• 2020

The coexistence of craniofacial cleft and bilateral choanal atresia has only been reported in three cases in the literature, and only one of those cases involved a Tessier number 3 facial cleft. It is also rare for bilateral choanal atresia to be found in adulthood, with 10 previous cases reported in the literature. This report presents the case of a 19-year-old woman with a Tessier number 3 facial cleft who was diagnosed with bilateral choanal atresia in adulthood. At first, the diagnosis of bilateral choanal atresia was missed and septoplasty was performed. After septoplasty, the patient's symptoms did not improve, and an endoscopic examination revealed previously unnoticed bilateral choanal atresia. Computed tomography showed left membranous atresia and right bony atresia. The patient underwent an operation for opening and widening of the left choana with an image-guided navigation system (IGNS), which enabled accurate localization of the lesion while ensuring patient safety. Postoperatively, the patient became able to engage in nasal breathing and reported that it was easier for her to breathe, and there were no signs of restenosis at a 26-month follow-up. The patient was successfully treated with an IGNS.

• Imaging Science in Dentistry
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• 제47권3호
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• pp.199-207
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• 2017

Purpose: Evaluation of alveolar bone is important in the diagnosis of dental diseases. The periodontal ligament space is difficult to clearly depict in cone-beam computed tomography images because the reconstruction filter conditions during image processing cause image blurring, resulting in decreased spatial resolution. We examined different reconstruction filters to assess their ability to improve spatial resolution and allow for a clearer visualization of the periodontal ligament space. Materials and Methods: Cone-beam computed tomography projections of 2 skull phantoms were reconstructed using 6 reconstruction conditions and then compared using the Thurstone paired comparison method. Physical evaluations, including the modulation transfer function and the Wiener spectrum, as well as an assessment of space visibility, were undertaken using experimental phantoms. Results: Image reconstruction using a modified Shepp-Logan filter resulted in better sensory, physical, and quantitative evaluations. The reconstruction conditions substantially improved the spatial resolution and visualization of the periodontal ligament space. The difference in sensitivity was obtained by altering the reconstruction filter. Conclusion: Modifying the characteristics of a reconstruction filter can generate significant improvement in assessments of the periodontal ligament space. A high-frequency enhancement filter improves the visualization of thin structures and will be useful when accurate assessment of the periodontal ligament space is necessary.

• Korean Journal of Radiology
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• 제22권6호
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• pp.912-921
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• 2021

Objective: To compare the performance of the deep learning-based lesion detection algorithm (DLLD) in detecting liver metastasis with that of radiologists. Materials and Methods: This clinical retrospective study used 4386-slice computed tomography (CT) images and labels from a training cohort (502 patients with colorectal cancer [CRC] from November 2005 to December 2010) to train the DLLD for detecting liver metastasis, and used CT images of a validation cohort (40 patients with 99 liver metastatic lesions and 45 patients without liver metastasis from January 2011 to December 2011) for comparing the performance of the DLLD with that of readers (three abdominal radiologists and three radiology residents). For per-lesion binary classification, the sensitivity and false positives per patient were measured. Results: A total of 85 patients with CRC were included in the validation cohort. In the comparison based on per-lesion binary classification, the sensitivity of DLLD (81.82%, [81/99]) was comparable to that of abdominal radiologists (80.81%, p = 0.80) and radiology residents (79.46%, p = 0.57). However, the false positives per patient with DLLD (1.330) was higher than that of abdominal radiologists (0.357, p < 0.001) and radiology residents (0.667, p < 0.001). Conclusion: DLLD showed a sensitivity comparable to that of radiologists when detecting liver metastasis in patients initially diagnosed with CRC. However, the false positives of DLLD were higher than those of radiologists. Therefore, DLLD could serve as an assistant tool for detecting liver metastasis instead of a standalone diagnostic tool.

• 대한영상의학회지
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• 제83권1호
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• pp.149-161
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• 2022

목적 3-tesla (이하 T) 자기공명영상에서 비특이 침윤성 유방암의 컴퓨터보조진단 인자들과 병리적 면역조직화학 표지자들과의 상관성을 알아보고자 하였다. 대상과 방법 2018년 1월부터 2019년 4월까지 비특이 침윤성 유방암으로 진단받은 총 94명의 3T 자기공명영상에서 컴퓨터보조진단 시스템을 통해 얻은 혈관조영부피, 최대 조영증강, 조기 및 지연 조영증강 양상과 면역화학인자와 유방암의 분자형 아형과의 상관성을 Dwass, Steel, Critchlow-Fligner 비교 분석과 이분형 로지스틱 회귀 분석을 이용하여 후향적으로 연구하였다. 결과 혈관조영부피가 큰 비특이 침윤성 유방암이 핵등급과 조직학적 등급이 높고, 림프절 전이가 있고, 에스트로겐 수용체/프로게스테론 수용체 음성, 인간 표피성장인자수용체 2/Ki-67 양성이 많았다. Ki-67 양성인 비특이 침윤성 유방암에서 지연기 소실 성분 비율이 높고 지연기 지속 조영증강 비율이 낮았다. 이항회귀분석에서는 컴퓨터보조진단 시스템의 요소 중 혈관조영부피 인자가 독립적으로 핵등급, 조직학적 등급, 림프절 전이, 에스트로겐/프로게스테론 수용체, 인간 표피성장인자수용체 2와 Ki-67과 상관성이 있고, 지연기 소실 및 지속 조영증강 인자가 Ki-67과 상관성이 있었다. 결론 조영증강 유방 MRI 컴퓨터보조진단 시스템 인자 중 혈관조영부피 요소와 지연기 소실/지속 조영증강 비율이 예후 예측 인자로 알려진 면역화학인자들과 연관성이 높아 임상적 예후 예측 인자로서 이용될 수 있을 것으로 사료된다.

• 대한세포병리학회지
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• 제12권1호
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• pp.1-15
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• 2001

The Bethesda System (TBS) was first developed in 1988 for the need to enhance the communication of the cytopathologic findings to the referring physician in unambiguous diagnostic terms. The terminology used in this reporting system should reflect current understanding of the pathogenesis of cervical/vaginal disease so the framework of the reporting system should be flexible enough to accommodate advances in medicine including virology, molecular biology, and pathology. Three years after the Introduction of TBS, the second Bethesda workshop was held to set or amend diagnostic criteria for each categories of TBS. TBS 1991 is now widely used. The third Bethesda workshop, The Bethesda System 2001 Workshop, was held in National Cancer institute Bethesda, Maryland from April 30 to May 2, 2001. Again, the goals of this workshop were to promote effective communication and to clarify in reporting cervical cytopathology results to clinicians and to provide with the information to make appropriate decisions about diagnosis and treatment. Nine forum groups were made and there were Web-based bulletin board discussions between October, 2000 and the first week of April, 2001. On the basis of bulletin board comments and discussions, the forum moderators recommended revised terminologies in the Workshop. Hot discussions were followed after the presentation by forum moderators during the workshop. Terminologies confusing clinicians and providing no additional informations regarding patient management were deleted in the workshop to clarify the cervicovaginal cytology results. Any informations related to the patient management were encouraged to add. So 'Satisfactory for evaluation but limited by...' of 'Specimen Adequacy' catergory was deleted. Terminology of 'Unsatisfactory' was further specified as 'Specimen rejected' and 'Specimen processed and examined, but unsatisfactory'. Terminologies of 'Benign Cellular Change' and 'Within Normal Limits' were combined and terminology was changed to 'Negative for intraepithelial lesion or malignancy'. In General categorization, category 'Other' was newly inserted and the presence of 'Endometrial cells' in women over 40 years old can be checked. Although the category 'Benign Cellular Change' was deleted, the organisms or reactive changes of this category can be listed in the descriptive diagnoses. Terminologies of ASCUS and AGUS were changed to atypical squamous cell and atypical glandular cell, respectively. Diagnostic term of 'Adenocarcinoma in situ', which is highly reproducible with reliable diagnostic criteria, was newly Inserted. The category of hormonal evaluation was deleted. Criteria for liquid-based specimen were discussed. Reporting by computer-assisted cytology was discussed and terminology for automated review was newly inserted. This is not the final edition of Bethesda 2001. The final document can be prepared before the ASCCP meeting in which Consensus Guidelines for the Management on Cytology Abnormalities and Cervical Precursors will develop in September 2001.

• Imaging Science in Dentistry
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• 제42권3호
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• pp.139-146
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• 2012

Purpose: An individual surgical stent fabricated from computed tomography (CT) data, called a CT-guided stent, would be useful for accurate installation of implants. The purpose of the present study was to introduce a newly developed CT-guided stent with a simple design and evaluate the accuracy of the stent placement. Materials and Methods: A resin template was fabricated from a hog mandible and a specially designed plastic plate, with 4 metal balls inserted in it for radiographic recognition, was attached to the occlusal surface of the template. With the surgical stent applied, CT images were taken, and virtual implants were placed using software. The spatial positions of the virtually positioned implants were acquired and implant guiding holes were drilled into the surgical stent using a specially designed 5-axis drilling machine. The surgical stent was placed on the mandible and CT images were taken again. The discrepancy between the central axis of the drilled holes on the second CT images and the virtually installed implants on the first CT images was evaluated. Results: The deviation of the entry point and angulation of the central axis in the reference plane were $0.47{\pm}0.27$ mm, $0.57{\pm}0.23$ mm, and $0.64{\pm}0.16^{\circ}$, $0.57{\pm}0.15^{\circ}$, respectively. However, for the two different angulations in each group, the $20^{\circ}$ angulation showed a greater error in the deviation of the entry point than did the $10^{\circ}$ angulation. Conclusion: The CT-guided template proposed in this study was highly accurate. It could replace existing implant guide systems to reduce costs and effort.