• Imaging Science in Dentistry
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• v.53 no.4
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• pp.303-312
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• 2023

Purpose: This study investigated the prevalence of developmental and acquired pathologic conditions associated with impacted third molars (3Ms) in a Southern Brazilian population and evaluated whether demographic and tooth characteristics were correlated with the presence of bone or tooth lesions. Materials and Methods: Panoramic radiographs were assessed for developmental (bone-related) or acquired (tooth-related) pathoses associated with impacted upper or lower 3Ms. Data on tooth positioning, tooth development, and patient demographics were collected. A trained, calibrated postgraduate student evaluated all images. Binary and multivariate logistic regression models were used to assess associations between outcomes and the demographic and radiographic variables. The threshold for statistical significance was set at 5% (P<0.05). Results: The sample comprised panoramic radiographs from 2054 patients, predominantly female (59.2%), with a mean age of 27.2±11.5 years. Overall, 4066 impacted 3Ms were evaluated, revealing 471 (11.6%) developmental and 710 (17.5%) acquired pathoses. Among the developmental pathoses, 460 (95.2%) were indicative of dentigerous cysts. Male sex, lower 3M location, vertical or distoangular positioning, and incomplete root formation were associated with an elevated likelihood of developmental pathology. Lower tooth position, complete root formation, and partial eruption were linked to an increased probability of an acquired pathology in the third or second molar. Conclusion: The prevalence of pathologic conditions associated with impacted 3Ms was low. Male sex, lower 3M placement, horizontal or distoangular positioning, and incomplete root formation were associated with developmental pathoses, while lower tooth position, complete root formation, and partial eruption were related to acquired pathoses.

• Imaging Science in Dentistry
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• v.54 no.1
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• pp.63-69
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• 2024

Purpose: The objective of this study was to determine the minimum number of teeth in the anterior dental arch that would yield accurate results for individual identification in forensic contexts. Materials and Methods: The study involved the analysis of 28 sets of 3-dimensional (3D) point cloud data, focused on the labial surface of the anterior teeth. These datasets were superimposed within each group in both genuine and imposter pairs. Group A incorporated data from the right to the left central incisor, group B from the right to the left lateral incisor, and group C from the right to the left canine. A comprehensive analysis was conducted, including the evaluation of root mean square error (RMSE) values and the distances resulting from the superimposition of dental arch segments. All analyses were conducted using CloudCompare version 2.12.4 (Telecom ParisTech and R&D, Kyiv, Ukraine). Results: The distances between genuine pairs in groups A, B, and C displayed an average range of 0.153 to 0.184mm. In contrast, distances for imposter pairs ranged from 0.338 to 0.522 mm. RMSE values for genuine pairs showed an average range of 0.166 to 0.177, whereas those for imposter pairs ranged from 0.424 to 0.638. A statistically significant difference was observed between the distances of genuine and imposter pairs(P<0.05). Conclusion: The exceptional performance observed for the labial surfaces of anterior teeth underscores their potential as a dependable criterion for accurate 3D dental identification. This was achieved by assessing a minimum of 4 teeth.

• The Korean journal of internal medicine
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• v.39 no.2
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• pp.283-294
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• 2024

Background/Aims: Epicardial adipose tissue (EAT) shares pathophysiological properties with other visceral fats and potentially triggers local inflammation. However, the association of EAT with cardiovascular disease (CVD) is still debatable. The study aimed to observe the changes and associations in EAT and risk factors over time, as well as to investigate whether EAT was associated with CVD. Methods: A total of 762 participants from Seoul National University Hospital (SNUH) and SNUH Gangnam Center were included in this study. EAT was measured using coronary computed tomography angiography. Results: Baseline EAT level was positively associated with body mass index (BMI), calcium score, atherosclerotic cardiovascular disease (ASCVD) 10-year risk score, glucose, triglycerides (TG)/high-density lipoprotein (HDL), but not with total cholesterol, low-density lipoprotein (LDL). At follow-up, EAT levels increased in all groups, with low EAT groups demonstrating a significant increase in EAT per year. Change in EAT was associated with a change in BMI, TG/HDL, and glucose, while changes in LDL, calcium score, and ASCVD 10-year risk score were not associated. Although calcium score and ASCVD 10-year risk score were associated with CVD events, baseline information of EAT, baseline EAT/body surface area, or EAT change was not available. Conclusions: Metabolic risks, e.g., BMI, TG/HDL, and glucose, were associated with EAT change per year, whereas classical CVD risks, e.g., LDL, calcium score, and ASCVD 10-year risk score, were not. The actual CVD event was not associated with EAT volume, warranting future studies combining qualitative assessments with quantitative ones.

• Imaging Science in Dentistry
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• v.54 no.3
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• pp.221-231
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• 2024

Purpose: Multiple myeloma (MM) is a rare cancer that is typically managed with bisphosphonates to slow bone resorption and prevent skeletal complications. This study aimed to identify imaging patterns in MM patients receiving bisphosphonate therapy. Materials and Methods: This systematic review included studies investigating maxillomandibular bone alterations based on imaging examinations in MM patients treated with bisphosphonates. The selected studies were qualitatively assessed using the Critical Appraisal Tools from SUMARI. Results: Six studies, involving 669 MM patients, were included, with 447 receiving bisphosphonate treatment. The majority were treated with pamidronate, zoledronate, or a combination of both. Seventy patients developed medication-related osteonecrosis of the jaw (MRONJ), predominantly in the mandible, characterized by the presence of bony sequestrum, bone sclerosis, increased periodontal ligament space, osteolytic lesions, and osteomyelitis as observed in imaging analyses. For non-MRONJ lesions, the mandible also exhibited the highest frequency of asymptomatic bone alterations. These ranged from "punched-out" osteolytic lesions or "soap bubble" lesions to solitary bone lesions, areas of bone sclerosis, abnormalities of the hard palate, osteoporosis, non-healed alveoli, and cortical bone rupture. Conclusion: MM patients treated with bisphosphonates display radiographic patterns of maxillomandibular bone lesions. These patterns aid in diagnosis and facilitate early and targeted treatment, thereby contributing to improved morbidity outcomes for these patients.

• Imaging Science in Dentistry
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• v.54 no.3
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• pp.240-250
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• 2024

Purpose: This study was performed to assess the clinical validity and accuracy of a deep learning-based automatic landmarking algorithm for cone-beam computed tomography (CBCT). Three-dimensional (3D) CBCT head measurements obtained through manual and automatic landmarking were compared. Materials and Methods: A total of 80 CBCT scans were divided into 3 groups: non-surgical (39 cases); surgical without hardware, namely surgical plates and mini-screws (9 cases); and surgical with hardware (32 cases). Each CBCT scan was analyzed to obtain 53 measurements, comprising 27 lengths, 21 angles, and 5 ratios, which were determined based on 65 landmarks identified using either a manual or a 3D automatic landmark detection method. Results: In comparing measurement values derived from manual and artificial intelligence landmarking, 6 items displayed significant differences: R U6CP-L U6CP, R L3CP-L L3CP, S-N, Or_R-R U3CP, L1L to Me-GoL, and GoR-Gn/S-N (P<0.05). Of the 3 groups, the surgical scans without hardware exhibited the lowest error, reflecting the smallest difference in measurements between human- and artificial intelligence-based landmarking. The time required to identify 65 landmarks was approximately 40-60 minutes per CBCT volume when done manually, compared to 10.9 seconds for the artificial intelligence method (PC specifications: GeForce 2080Ti, 64GB RAM, and an Intel i7 CPU at 3.6 GHz). Conclusion: Measurements obtained with a deep learning-based CBCT automatic landmarking algorithm were similar in accuracy to values derived from manually determined points. By decreasing the time required to calculate these measurements, the efficiency of diagnosis and treatment may be improved.

• Progress in Medical Physics
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• v.19 no.1
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• pp.49-55
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• 2008

This study aims to conduct the comparative analysis of the radiation dose according to before and after the calibration of the ionization chamber used for measuring radiation dose in the MDCT, as well as of $CTDI_w$ according to temperature and pressure correction factors in the CT room. A comparative analysis was conducted based on the measured MDCT (GE light speed plus 4 slice, USA) data using head and body CT dosimetric phantom, and Model 2026C electrometer (RADICAL 2026C, USA) calibrated on March 21, 2007. As a result, the $CTDI_w$ value which reflected calibration factors, as well as correction factors of temperature and pressure, was found to be the range of $0.479{\sim}3.162mGy$ in effective radiation dose than the uncorrected values. Also, under the routine abdomen routine CT image acquisition conditions used in reference hospitals, patient effective dose was measured to indicate the difference of the maximum of 0.7 mSv between before and after the application of such factors. These results imply that the calibration of the ion chamber, and the correction of temperature and pressure of the CT room are crucial in measuring and calculating patient effective dose. Thus, to measure patient radiation dose accurately, the detailed information should be made available regarding not only the temperature and pressure of the CT room, but also the humidity and recombination factor, characteristics of X-ray beam quality, exposure conditions, scan region, and so forth.

• Journal of Radiation Protection and Research
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• v.32 no.3
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• pp.123-133
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• 2007

Z-axis automatic tube current modulation technique automatically adjusts tube current based on size of body region scanned. The purpose of the current study was to compare noise, and radiation dose of multi-detector row CT (MDCT) of lower extremity performed with Z-axis modulation technique of automatic tube current modulation with manual selection fixed tube current. Fifty consecutive underwent MDCT venography of lower extremity with use of a MDCT scanner fixed tube current and Z-axis automatic tube current modulation technique (10, 11 and 12 HU noise index, $70{\sim}450\;mA$). Scanning parameters included 120 kVp, 0.5 second gantry rotation time, 1.35:1 beam pitch, and 1 mm reconstructed section thickness. For each subject, images obtained with Z-axis modulation were compared with previous images obtained with fixed tube current (200, 250, 300 mA) and with other parameters identical. Images were compared for noise at five levels: iliac, femoral, popliteal, tibial, and peroneal vein of lower extremity. Tube current and gantry rotation time used for acquisitions at these levels were recorded. All CT examinations of study and control groups were diagnostically acceptable, though objective noise was significantly more with Z-axis automatic tube current modulation. Compared with fixed tube current, 2-axis modulation resulted in reduction of CTDIvol (range, $-6.5%{\sim}-35.6%$) and DLP (range, $-0.2%{\sim}-20.2%$). Compared with manually selected fixed tube current, 2-axis automatic tube current modulation resulted in reduced radiation dose at MDCT of lower extremity venography.

• Journal of the Korean Society of Radiology
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• v.18 no.1
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• pp.45-52
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• 2024

In this study, an AI-based algorithm was developed to prevent image quality deterioration and reading errors due to patient movement in PET/CT examinations that use radioisotopes in medical institutions to test cancer and other diseases. Using the Mothion Free software developed using, we checked the degree of correction of movement due to breathing, evaluated its usefulness, and conducted a study for clinical application. The experimental method was to use an RPM Phantom to inject the radioisotope 18F-FDG into a vacuum vial and a sphere of a NEMA IEC body Phantom of different sizes, and to produce images by directing the movement of the radioisotope into a moving lesion during respiration. The vacuum vial had different degrees of movement at different positions, and the spheres of the NEMA IEC body Phantom of different sizes produced different sizes of lesions. Through the acquired images, the lesion volume, maximum SUV, and average SUV were each measured to quantitatively evaluate the degree of motion correction by Motion Free. The average SUV of vacuum vial A, with a large degree of movement, was reduced by 23.36 %, and the error rate of vacuum vial B, with a small degree of movement, was reduced by 29.3 %. The average SUV error rate at the sphere 37mm and 22mm of the NEMA IEC body Phantom was reduced by 29.3 % and 26.51 %, respectively. The average error rate of the four measurements from which the error rate was calculated decreased by 30.03 %, indicating a more accurate average SUV value. In this study, only two-dimensional movements could be produced, so in order to obtain more accurate data, a Phantom that can embody the actual breathing movement of the human body was used, and if the diversity of the range of movement was configured, a more accurate evaluation of usability could be made.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2004.11a
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• pp.53-55
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• 2004

In emergency cases, such as the severe trauma involving the fracture of skull, spine, or cervical bone, from auto accident or a fall, and/or pneumothorax which can not be diagnosed exactly by the eye examination, it is necessary the radiological examination during transferring to the hospital for emergency care. The aim of this study was to design and evaluate the prototype of mobile medical image communication system based on CDMA 1X EVDO. The system consists of a laptop computer used as a transmit DICOM client, linked with cellular phone which support to the CDMA 1X EVDO communication service, and a receiving DICOM server installed in the hospital. The DR images were stored with DICOM format in the storage of transmit client. Those images were compressed into JPEG2000 format and transmitted from transmit client to the receiving server. All of those images were progressively transmitted to the receiving server and displayed on the server monitor. To evaluate the image quality, PSNR of compressed image was measured. Also, several field tests had been performed using commercial CDMA2000 1X-EVDO reverse link with the TCP/IP data segments. The test had been taken under several velocity of vehicle in seoul areas.

• Journal of radiological science and technology
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• v.30 no.4
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• pp.343-347
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• 2007

Cascade Stomach is commonly found in obese patients. This study examined the physical factors, such as gender, age, height, weight and level of obesity, associated with a cascade stomach. Over a 12 month period between 2007 a series upper gastrointestinal examinations were carried out on 3,320 people, which included 564 patients with a Cascade Stomach. The results are as follows : 1. A cascade stomach was observed in 564(16.9%) out of 3,320 subjects. 2. A body mass index(BMI) > 120% was observed in 226 of the 564 cascade stomach patients. 3. Among those with a BMI > 120, 63.7% were female, 45.6% were aged between 50-59 years, 49.1% were between 151-160 cm in height and 31.0% were above 76 kg in weight. 4. The symptoms observed in the cascade stomach and obesity groups were subclinical(62.6% and 57.5%, respectively), dyspepsia(16.8% and 17.3%, respectively) and gastric soreness(10.8% and 15.0%, respectively). The incidence of a cascade stomach is higher in those with obesity. In addition, there is a higher incidence in females, those aged between 50 and 59, those between 151 and 160 cm in height and those weighing more than 76 kg. The main symptoms observed were subclinical, followed in order by dyspepsia and gastric soreness. This study showed a strong association between a cascade stomach and obesity. However, more studies will be needed to confirm this.