• Imaging Science in Dentistry
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• v.36 no.3
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• pp.123-129
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• 2006

The use of computed tomography for dental procedures has increased recently. Cone beam computed tomography (CBCT) systems have been designed for imaging hard tissues of the dentomaxillofacial region. CBCT is capable of providing high resolution in images of high diagnostic quality. This technology allows for 3-dimensional representation of the dentomaxillofacial skeleton with minimal distortion, but at lower equipment cost, simpler image acquisition and lower patient dose. Because this technology produces images with isotropic sub-millimeter spatial resolution, it is ideally suited for dedicated dentomaxillofacial imaging. In this paper, we provide a brief overview of cone beam scanning technology and compare it with the fan beam scanning used in conventional CT and the basic principles of currently available CBCT systems.

• Imaging Science in Dentistry
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• v.50 no.4
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• pp.359-363
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• 2020

Ameloblastic carcinoma is a rare odontogenic malignant tumor with the histologic features of both ameloblastoma and carcinoma. It occurs more frequently in the mandible than in the maxilla and it may appear de novo or develop from a preexisting ameloblastoma or odontogenic cyst. Rapidly progressing, painful swelling is the most common symptom, and radiographically, it shows significant bone resorption and cortical perforation. This report described a case of ameloblastic carcinoma in a 45-year-old man who presented with swelling in the left mandible. The lesion showed combined features of benign findings, such as an expansile cortex with a distinct border, and malignant findings, such as a large exophytic mass with frank bone resorption. Excisional biopsy was performed and a final diagnosis of ameloblastic carcinoma was made.

• Imaging Science in Dentistry
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• v.52 no.4
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• pp.409-413
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• 2022

This report presents a rare case where a displaced temporomandibular joint (TMJ) disc was reduced to its normal position after orthognathic surgery, and long-term magnetic resonance imaging (MRI) follow-up visualized these postoperative changes. A 22-year-old male patient presented for facial asymmetry. He also complained of pain in the right TMJ area, and MRI showed disc displacements in both TMJs. After orthognathic surgery for facial asymmetry correction, the TMJ was re-evaluated. The symptom had resolved and the disc was positioned within the normal range during mouth opening. However, 6 and a half years after surgery, he complained of recurrent pain in the right joint, and MRI revealed medial disc displacement in the right TMJ. In conclusion, the influence of orthognathic surgery on the disc position might continue for a long time until the TMJ adapts to the new position. Careful and long-term follow-up is suggested to assess the TMJ complex.

• Imaging Science in Dentistry
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• v.52 no.4
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• pp.415-419
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• 2022

A central odontogenic fibroma is a rare benign tumor composed of mature fibrous connective tissue with variable amounts of odontogenic epithelium. It appears at similar rates in the maxilla and mandible. In the maxilla, it usually occurs anterior to the molars. Radiographically, central odontogenic fibroma commonly presents as a multilocular or unilocular radiolucency with a distinct border. This paper reports a case of an aggressive central odontogenic fibroma involving the right posterior maxilla of a 53-year-old man. Radiographs showed an extensive soft tissue mass involving the entire right maxilla with frank bone resorption. The patient had a history of 2 operations in the region, both more than 2 decades ago. Although it was impossible to confirm the previous diagnoses, it was presumed that this case was a recurrent lesion.

• Korean Journal of Radiology
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• v.25 no.7
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• pp.656-661
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• 2024

Evaluating the performance of a binary diagnostic test, including artificial intelligence classification algorithms, involves measuring sensitivity, specificity, positive predictive value, and negative predictive value. Particularly when comparing the performance of two diagnostic tests applied on the same set of patients, these metrics are crucial for identifying the more accurate test. However, comparing predictive values presents statistical challenges because their denominators depend on the test outcomes, unlike the comparison of sensitivities and specificities. This paper reviews existing methods for comparing predictive values and proposes using the permutation test. The permutation test is an intuitive, non-parametric method suitable for datasets with small sample sizes. We demonstrate each method using a dataset from MRI and combined modality of mammography and ultrasound in diagnosing breast cancer.

• Imaging Science in Dentistry
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• v.39 no.4
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• pp.199-203
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• 2009

Purpose : To measure dose-width product (DWP) values used for dental panoramic radiography in Anyang city, Korea. Materials and Methods : Thirty-six panoramic dental radiographic sets (17 analogue panoramic sets and 19 digital panoramic sets) in 36 dental clinics in Anyang city were included in the study. Each patient's panoramic exposure parameters were simulated and the panoramic radiation doses were measured at the secondary collimator using a Mult-O-Meter (Unfors Instruments, Billdal, Sweden) at each dental clinic during 2006. The third quartile DWP was determined from 310 surface dose measurements on adult. Results : The third quartile DWP for adult panoramic radiograph was 106.7 mGy mm. For analogue and digital panoramic radiograph, 3/4 DWP were 116.8 mGy mm and 72 mGy mm respectively. The overall third quartile DWP of panoramic radiography was 106.7 mGy mm. Conclusion : The measured 3/4 DWPs were higher than the 3/4 DWP of 65 mGy mm recommended by NRPB. Dentists who are operating above the reference dose should lower their panoramic exposure doses below the recommended reference value by changing the exposure parameters and/or their panoramic equipments.

• Journal of Yeungnam Medical Science
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• v.38 no.1
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• pp.78-82
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• 2021

Pancreatic metastasis from malignant phyllodes tumor (PT) of the breast is rare, and only a few cases have been reported in the literature. Here, we report a case of pancreatic metastasis from malignant PT of the breast in a 48-year-old woman. She had had three episodes of recurrence of malignant PT in her right breast. She presented with epigastric pain for 2 months. Computed tomography and magnetic resonance imaging revealed a 6 cm-sized, well-defined, heterogeneous mass with peripheral enhancement in the body of the pancreas. Endoscopic ultrasonography-guided fine-needle aspiration was performed, and the pathologic report suggested spindle cell mesenchymal neoplasm. Subsequently, surgical excision was performed, and the mass was confirmed as a metastatic malignant PT. The imaging findings are discussed and the literature is briefly reviewed in this report.

• Journal of the Korean Society of Radiology
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• v.81 no.6
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• pp.1397-1411
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• 2020

Purpose To survey the perception, knowledge, wishes, and expectations of Korean radiology residents regarding artificial intelligence (AI) in radiology. Materials and Methods From June 4th to 7th, 2019, questionnaires comprising 19 questions related to AI were distributed to 113 radiology residents. Results were analyzed based on factors such as the year of residency and location and number of beds of the hospital. Results A total of 101 (89.4%) residents filled out the questionnaire. Fifty (49.5%) respondents had studied AI harder than the average while 68 (67.3%) had a similar or higher understanding of AI than the average. In addition, the self-evaluation and knowledge level of AI were significantly higher for radiology residents at hospitals located in Seoul and Gyeonggi-do compared to radiology residents at hospitals located in other regions. Furthermore, the self-evaluation and knowledge level of AI were significantly lower in junior residents than in residents in the 4th year of training. Of the 101 respondents, only 16 (15.8%) had experiences in AI-related study while 91 (90%) were willing to participate in AI-related study in the future. Conclusion Organizational efforts through a radiology society would be needed to meet the need of radiology trainees for AI education and to promote the role of radiologists more adequately in the era of medical AI.

• Journal of Yeungnam Medical Science
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• v.39 no.1
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• pp.18-23
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• 2022

Background: This study was performed to evaluate periprocedural factors, complications, and repuncture rate of the newly developed puncture needle and compare it with the routinely used puncture needle for ultrasound (US)-guided paracentesis. Methods: We retrospectively identified 137 patients who underwent US-guided paracentesis between July 2018 and March 2019. Among them, 82 patients underwent US-guided paracentesis with a newly developed puncture needle. The other 55 patients underwent US-guided paracentesis with a routinely used puncture needle. The periprocedural factors, complications, and repuncture rate were compared between the two groups using the Mann-Whitney U test and Fisher exact test. The repuncture-associated factors were assessed using logistic regression analysis. Results: There were no major or minor complications in either group. The rate of repuncture was significantly lower in the group using the newly developed puncture needle compared with the group using the routinely used puncture needle (p=0.01). The duration of the procedure was significantly shorter with the newly developed puncture needle compared with the routinely used puncture needle (p=0.01). In univariate analysis, the thickness of the abdominal wall (p=0.04) and the use of the newly developed puncture needle (p=0.01) were significantly associated with the rate of repuncture. In multivariate analysis, only the use of the newly developed puncture needle was significantly associated with the rate of repuncture. Conclusion: Using this novel puncture needle with a hard plastic sheath and plastic wings, the rate of repuncture and the duration of the procedure were decreased without complications of US-guided paracentesis.

• Imaging Science in Dentistry
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• v.50 no.2
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• pp.153-159
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• 2020

Purpose: This study was conducted evaluate the influence of reconstruction parameters of micro-computed tomography (micro-CT) images on bone mineral density (BMD) analyses. Materials and Methods: The sample consisted of micro-CT images of the maxillae of 5 Wistar rats, acquired using a SkyScan 1174 unit (Bruker, Kontich, Belgium). Each acquisition was reconstructed following the manufacturer's recommendations(standard protocol; SP) for the application of artifact correction tools(beam hardening correction [BHC], 45%; smoothing filter, degree 2; and ring artifact correction [RAC], level 5). Additionally, images were reconstructed with 36 protocols combining different settings of artifact correction tools (P0 to P35). BMD analysis was performed for each reconstructed image. The BMD values obtained for each protocol were compared to those obtained using the SP through repeated-measures analysis of variance with the Dunnett post hoc test(α=0.05). Results: The BMD values obtained from all protocols that used a BHC of 45% did not significantly differ from those obtained using the SP (P>0.05). The other protocols all yielded significantly different BMD values from the SP(P<0.05). The smoothing and RAC tools did not affect BMD values. Conclusion: BMD values measured on micro-CT images were influenced by the BHC level. Higher levels of BHC induced higher values of BMD.