• Journal of the Korean Orthopaedic Association
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• v.55 no.5
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• pp.405-410
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• 2020

Purpose: Pedicle screw insertion has been traditionally used as a surgical treatment for degenerative lumbar spine disease. As an alternative, the cortical-bone trajectory screw allows less invasive posterior lumbar fixation and excellent mechanical stability, as reported in several biomechanical studies. This study evaluated the clinical and radiological results of a case of early failure of cortical-bone screw fixation in posterior fixation and union after posterior decompression. Materials and Methods: This study examined 311 patients who underwent surgical treatment from 2013 to 2018 using cortical orbital screws as an alternative to traditional pedicle screw fixation for degenerative spinal stenosis and anterior spine dislocation of the lumbar spine. Early fixation failure after surgery was defined as fixation failure, such as loosening, pull-out, and breakage of the screw on computed tomography (CT) and radiographs at a follow-up of six months. Results: Early fixation failure occurred in 46 out of 311 cases (14.8%), screw loosening in 46 cases (14.8%), pull-out in 12 cases (3.9%), and breakage in four cases (1.3%). An analysis of the site where the fixation failure occurred revealed the following, L1 in seven cases (15.2%), L2 in three cases (6.5%), L3 in four cases (8.7%), L4 in four cases (8.7%), L5 in four cases (8.7%), and S1 in 24 cases (52.2%). Among the distal cortical bone screws, fixation failures such as loosening, pull-out, and breakage occurred mainly in the S1 screws. Conclusion: Cortical-bone trajectory screw fixation may be an alternative with comparable clinical outcomes or fewer complications compared to conventional pedicle screw fixation. On the other hand, in case with osteoporosis and no anterior support structure particularly at L5-S1 fusion sites were observed to have result of premature fixation failures such as relaxation, pull-out, and breakage.

• Journal of the Korean Orthopaedic Association
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• v.55 no.4
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• pp.324-330
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• 2020

Purpose: Korean studies on the prevalence of a tarsal coalition are quite rare, and there are very few reports on the prevalence of multiple tarsal coalitions among adults in the foreign literature. Therefore, this study examined the characteristics and prevalence of tarsal coalition in the Korean population based on imaging tests. Materials and Methods: The prevalence of tarsal coalition and its anatomical location and histological classification were reviewed retrospectively among 4,711 patients (4,454 males and 257 females) with an ankle sprain or ankle fracture who underwent foot and ankle computed tomography and magnetic resonance imaging between March 2009 and February 2019 at the authors' institution. Results: Over a period of 10 years, 78 patients (1.7%) had a tarsal coalition, among whom 53 patients (67.9%) had an isolated tarsal coalition and 25 patients (32.1%) had multiple tarsal coalitions. Regarding the anatomical location, a talocalcaneal coalition was the most common type in both isolated (31 patients, 37 cases [62.7%]) and multiple (22 patients, 23 cases [45.1%]) tarsal coalitions. In the isolated coalition group, the second-most common type was calcaneonavicular coalition (10 patients, 16.9%), followed by naviculocuneiform (nine patients, 15.3%) and cuboidonavicular coalitions (three patients, 5.1%). In the multiple coalition group, the second-most common coalition type was calcaneonavicular coalition (14 patients, 14 cases [27.5%]), followed by talonavicular coalition (six patients, six cases [11.8%]). From a total of 60 cases of talocalcaneal coalition, 24 cases (40.0%) were in the posterior facet, 18 cases (30.0%) in the middle facet, and four cases (6.7%) in the anterior facet. Regarding the histological classification, cartilaginous coalition was the most common in both single (32 patients, 35 cases [59.3%]) and multiple (20 patients, 37 cases [72.5%]) coalition groups. Conclusion: The present study found that talocalcaneal coalition was the most common type of tarsal coalition. In contrast to previous reports that a talocalcaneal coalition generally occurs in the middle facet, it was usually observed in the posterior facet in the present study. In addition, although multiple tarsal coalitions have been reported to be quite rare, this study confirmed that they are not rare and can occur in a range of patterns.

• Journal of Cadastre & Land InformatiX
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• v.52 no.2
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• pp.171-187
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• 2022

Recently, the demand and development for non-face-to-face services are rapidly progressing due to the pandemic caused by the COVID-19, and attention is focused on the metaverse at the center. Entering the era of the 4th industrial revolution, Metaverse, which means a world beyond virtual and reality, combines various sensing technologies and 3D reconstruction technologies to provide various information and services to users easily and quickly. In particular, due to the miniaturization and economic increase of convergence sensors such as unmanned aerial vehicle(UAV) capable of high-resolution imaging and high-precision LiDAR(Light Detection and Ranging) sensors, research on digital-Twin is actively underway to create and simulate real-life twins. In addition, Game engines in the field of computer graphics are developing into metaverse engines by expanding strong 3D graphics reconstuction and simulation based on dynamic operations. This study constructed a mirror-world type metaverse that reflects real-world coordinate-based reality using Unreal Engine 5, a recently announced metaverse engine, with accurate 3D spatial information data of convergence sensors based on unmanned aerial system(UAS) and LiDAR. and then, spatial information contents and simulations for users were produced based on various public data to verify the accuracy of reconstruction, and through this, it was possible to confirm the construction of a more realistic and highly utilizable metaverse. In addition, when constructing a metaverse that users can intuitively and easily access through the unreal engine, various contents utilization and effectiveness could be confirmed through coordinate-based 3D spatial information with high reproducibility.

• Journal of the Korean Orthopaedic Association
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• v.54 no.5
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• pp.435-439
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• 2019

Purpose: This study evaluated the efficacy of blood mixed cement for osteoporotic vertebral compression fractures in reducing the complications of percutaneous vertebroplasty using conventional cement. Materials and Methods: This study was performed retrospectively in 80 patients, from January 2016 to January 2017. Porous cement was formed by mixing 2, 4, and 6 ml of blood with 20 g of cement used previously. A tube with a diameter and length of 2.8 mm and 215 mm, respectively, was used and the polymerization temperature, setting time, and optimal passing-time were measured and compared with those using only conventional cement. Radiologically, the results were evaluated and compared. Results: The polymerization temperature was 70.3℃, 55.3℃, 52.7℃, and 45.5℃ in the conventional cement (R), 2 ml (B2), 4 ml (B4), and 6 ml (B6), respectively, and the corresponding setting time decreased from 960 seconds (R) to 558 seconds (B2), 533 seconds (B4), and 500 seconds (B6). The optimal passing-time was 45 seconds (B2), 60 seconds (B4), and 78 seconds (B6) at 73 seconds (R), respectively and as the amount of blood increased, it was similar to the cement passing-time. The radiological results showed that the height restoration rates and the vertebral subsidence rates similar among the groups. Two cases of adjacent vertebral compression fractures in the R group and one in the B2 and B4 groups were encountered, and the leakage rate of the cement was approximately two times higher than that in the conventional cement group. Conclusion: In conventional percutaneous vertebroplasty, the procedure of using autologous blood with cement decreased the polymerization temperature, reduced the setting time, and the incidence of cement leakage was low. These properties may contribute to more favorable mechanical properties that can reduce the complications compared to conventional cements alone.

• Journal of Intelligence and Information Systems
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• v.29 no.2
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• pp.171-187
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• 2023

When a person's face is recognized through a recording device such as a low-pixel surveillance camera, it is difficult to capture the face due to low image quality. In situations where it is difficult to recognize a person's face, problems such as not being able to identify a criminal suspect or a missing person may occur. Existing studies on face recognition used refined datasets, so the performance could not be measured in various environments. Therefore, to solve the problem of poor face recognition performance in low-quality images, this paper proposes a method to generate high-quality images by performing image quality improvement on low-quality facial images considering various environments, and then improve the performance of facial feature point detection. To confirm the practical applicability of the proposed architecture, an experiment was conducted by selecting a data set in which people appear relatively small in the entire image. In addition, by choosing a facial image dataset considering the mask-wearing situation, the possibility of expanding to real problems was explored. As a result of measuring the performance of the feature point detection model by improving the image quality of the face image, it was confirmed that the face detection after improvement was enhanced by an average of 3.47 times in the case of images without a mask and 9.92 times in the case of wearing a mask. It was confirmed that the RMSE for facial feature points decreased by an average of 8.49 times when wearing a mask and by an average of 2.02 times when not wearing a mask. Therefore, it was possible to verify the applicability of the proposed method by increasing the recognition rate for facial images captured in low quality through image quality improvement.

• Journal of the Korean Society of Radiology
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• v.83 no.6
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• pp.1342-1353
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• 2022

Purpose We compared the radiation dose and image quality between the 2nd generation and the 3rd generation dual-source single-energy (DSSE) and dual-source dual-energy (DSDE) CT of the abdomen. Materials and Methods We included patients undergoing follow-up abdominal CT after partial or radical nephrectomy in the first 10 months of 2019 (2nd generation DS CT) and the first 10 months of 2020 (3rd generation DS CT). We divided the 320 patients into 4 groups (A, 2nd generation DSSE CT; B, 2nd generation DSDE CT; C, 3rd generation DSSE CT; and D, 3rd generation DSDE CT) (n = 80 each) matched by sex and body mass index. Radiation dose and image quality (objective and subjective qualities) were compared between the groups. Results The mean size-specific dose estimation of 3rd generation DSDE CT group was significantly lower than that of the 2nd generation DSSE CT (42.5%, p = 0.013) and 2nd generation DSDE CT (46.9%, p = 0.015) groups. Interobserver agreement was excellent for the overall image quality (intraclass correlation coefficient [ICC]: 0.8867) and image artifacts (ICC: 0.9423). Conclusion Our results showed a considerable reduction in the radiation dose while maintaining high image quality with 3rd generation DSDE CT as compared to the 2nd generation DSDE CT and 2nd generation DSSE CT.

• Journal of the Korean Society of Radiology
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• v.82 no.5
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• pp.1196-1206
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• 2021

Purpose To construct a standard dataset of contrast-enhanced CT images of liver tumors to test the performance and safety of artificial intelligence (AI)-based algorithms for clinical decision support systems (CDSSs). Materials and Methods A consensus group of medical experts in gastrointestinal radiology from four national tertiary institutions discussed the conditions to be included in a standard dataset. Seventy-five cases of hepatocellular carcinoma, 75 cases of metastasis, and 30-50 cases of benign lesions were retrieved from each institution, and the final dataset consisted of 300 cases of hepatocellular carcinoma, 300 cases of metastasis, and 183 cases of benign lesions. Only pathologically confirmed cases of hepatocellular carcinomas and metastases were enrolled. The medical experts retrieved the medical records of the patients and manually labeled the CT images. The CT images were saved as Digital Imaging and Communications in Medicine (DICOM) files. Results The medical experts in gastrointestinal radiology constructed the standard dataset of contrast-enhanced CT images for 783 cases of liver tumors. The performance and safety of the AI algorithm can be evaluated by calculating the sensitivity and specificity for detecting and characterizing the lesions. Conclusion The constructed standard dataset can be utilized for evaluating the machine-learning-based AI algorithm for CDSS.

• Journal of the Korean Society of Radiology
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• v.83 no.1
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• pp.127-137
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• 2022

Purpose To assess the prevalence of incidentally detected lumbar spondylolysis in children. Materials and Methods We retrospectively reviewed the data of 809 patients under the age of 11 years (mean age, 7.0 ± 2.7 years; boys:girls = 479:330) who underwent abdominal and pelvic CT between March 2014 and December 2018. We recorded the presence, level, and laterality (unilateral or bilateral) of spondylolysis. Patients were divided into two groups based on the presence of spondylolysis: the spondylolysis (SP) and non-SP groups. Results In total, 21 cases of spondylolysis were detected in 20 patients (20/809, 2.5%). The mean age of the SP group was higher than that of the non-SP group (7.8 ± 1.8 vs. 6.9 ± 2.7 years, p > 0.05). The prevalence of spondylolysis in boys was higher than that in girls (15/479 [3.1%] vs. 5/330 [1.5%], p > 0.05). The prevalence of spondylolysis in school-age children (6-10 year olds) was higher than that in preschool-age children (0-5 year olds) (17/538 [3.2%] vs. 3/271 [1.1%], p > 0.05). L5 was the most common level of spondylolysis (76.2%); one 8-year-old boy had two-level spondylolysis. One case of isthmic spondylolisthesis was detected in a 10-year-old boy (1/809, 0.1%). There were 11 unilateral spondylolysis cases (11/21, 52.4%). Conclusion In our study, the prevalence of spondylolysis in children under the age of 11 was 2.5%. The prevalence was higher in boys than in girls and in school-age than in preschool-age children, despite the lack of any statistically significant differences.

• The Korean Journal of Nuclear Medicine
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• v.32 no.6
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• pp.490-496
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• 1998

Purpose: We evaluated brain perfusion SPECT findings of MELAS syndrome and mitochondrial myopathy in correlation with MR imaging in search of specific imaging features. Materials and Methods: Subjects were five patients (four females and one male; age range, 1 to 25 year) who presented with repeated stroke-like episodes, seizures or developmental delay or asymptomatic but had elevated lactic acid in CSF and serum. Conventional non-contrast MR imaging and Tc-99m-ethyl cysteinate dimer (ECD) brain perfusion SPECT were Performed and imaging features were analyzed. Results: MRI demonstrated increased T2 signal intensities in the affected areas of gray and white matters mainly in the parietal (4/5) and occipital lobes (4/5) and in the basal ganglia (1/5), which were not restricted to a specific vascular territory. SPECT demonstrated decreased perfusion in the corresponding regions of MRI lesions. In addition, there were perfusion defects in parietal (1 patient), temporal (2), and frontal (1) lobes and basal ganglia (1) and thalami (2). In a patient with mitochondrial myopathy who had normal MRI, decreased perfusion was noted in left parietal area and bilateral thalami. Conclusion: Tc-99m ECD SPECT imaging in patients with MELAS syndrome and mitochondrial myopathy showed hypoperfusion of parieto-occipital cortex, basal ganglia, thalamus and temporal cortex, which were not restricted to a specific vascular territory. There were no specific imaging features on SPECT. The significance of abnormal perfusion on SPECT without corresponding MR abnormalities needs to be evaluated further in larger number of patients.

• Journal of Chest Surgery
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• v.38 no.5 s.250
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• pp.349-356
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• 2005

Background: Arterial conduits using in coronary artery bypass grafting (CABG) have been known a great long term patency rates, and improved short and long term clinical outcomes. It has been reported that Off pump CABG has better clinical results than CABG using cardiopulmonary bypass. To evaluate the advantage of arterial conduits over venous conduits and to avoid the adverse effects of cardiopulmonary bypass, we performed total arterial Off pump CABG. Material and Method: From January 2001 to October 2004, Off pump CABG using only arterial conduits was performed on 325 patients with a mean age of $59.3\pm11.9$ years ($36\~83$). Mean ejection fraction was $55.4\pm14.0\%\;(15\~86).$ Angiography showed left main disease or triple-vessel disease in $81.9\%$ of the patients. Indications of using arterial conduits was stenosis $\ge50\%$ of left anterior descending artery, stenosis $\ge80\%$ of branches of left circumflex artery, and stenosis $\ge90\%$ of right coronary artery and its branches. Multi-slice computed tomography was performed on 194 patients to evaluate the short term patency rates. Result: A total of 928 distal anastomoses were performed and the average anastomoses per a patient were $2.86\pm0.78$. There was 1 operative mortality. Postoperative complications were mediastinitis in 6 patients ($1.8\%$), renal failure in 4 patients ($1.2\%$), perioperative myocardial infarction in 3 patients ($0.9\%$), reoperation for bleeding in 3 patients ($0.9\%$). There was no postoperative stroke. Patency rate of arterial conduits was $99.3\%$ (581/585). There were 4 stenoses or competitive flows in 2 radial arteries and 2 right internal mammary arteries. Conclusion: Total arterial Off pump CABG appears to be safe, showing a low surgical mortality and morbidity and excellent short term patency rates of arterial conduits.