• Journal of the Korean Society of Radiology
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• v.13 no.3
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• pp.325-332
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• 2019

This study analyzed the movement of tumors using 4DCT. Appropriate uniform IM were identified using TC, II and CI depending on ITV margins. DVH and NTCP were also compared in each case. Dose analysis on tumors with uniform IM showed that the optimal treatment plan for satisfying all TC, CI, II was evaluated as 2 mm in phase 20 and 3 mm in 40%. That was compared to the dose from the normal tissues of $PTV_{20}$, $PTV_{40}$. In the 20% radiation field, V5, V10, and V20 for the lungs increased 1.49, 1.26, and 0.65%, while 40% increased by 1.9, 2.41 and 1.23%. NTCP had a dose increase of 0.57 to 0.029% from 20% and 40%. There was a dose increase in the spinal cord and heart at uniform IM, but there was no significant difference. These data suggest that the ITV setting of 20%, phase for Respiratory Gated Radiotherapy using Novalis ExacTrac system can be applied with a uniform IM 2 mm and 40% with 3 mm for optimal treatment plan.

• Journal of the Korean Society of Radiology
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• v.81 no.2
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• pp.324-336
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• 2020

Cardiovascular calcifications can occur in various cardiovascular diseases and can serve as a biomarker for cardiovascular event prediction. Advances in CT have enabled evaluation of calcifications in cardiovascular structures not only on ECG-gated CT but also on non-ECG-gated CT. Therefore, many studies have been conducted on the clinical relevance of cardiovascular calcifications in patients. In this study, we divided cardiovascular calcifications into three classes, i.e., coronary artery, thoracic aorta, and cardiac valve calcifications, which are closely associated with cardiovascular events. Further, we briefly described pericardial calcifications, which can be found incidentally. Since the start of lung cancer screening in Korea in the second half of 2019, the number of non-enhanced, non-ECG-gated, low-dose chest CT has been increasing, and the number of incidentally found cardiovascular calcifications has also been increasing. Therefore, understanding the relevance of cardiovascular calcifications on non-enhanced, non-ECG-gated, low-dose chest CT and their proper reporting are important for radiologists.

• Korean Journal of Radiology
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• v.23 no.10
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• pp.1009-1018
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• 2022

Objective: This study aimed to investigate the feasibility of using artificial intelligence (AI) to identify normal chest radiography (CXR) from the worklist of radiologists in a health-screening environment. Materials and Methods: This retrospective simulation study was conducted using the CXRs of 5887 adults (mean age ± standard deviation, 55.4 ± 11.8 years; male, 4329) from three health screening centers in South Korea using a commercial AI (Lunit INSIGHT CXR3, version 3.5.8.8). Three board-certified thoracic radiologists reviewed CXR images for referable thoracic abnormalities and grouped the images into those with visible referable abnormalities (identified as abnormal by at least one reader) and those with clearly visible referable abnormalities (identified as abnormal by at least two readers). With AI-based simulated exclusion of normal CXR images, the percentages of normal images sorted and abnormal images erroneously removed were analyzed. Additionally, in a random subsample of 480 patients, the ability to identify visible referable abnormalities was compared among AI-unassisted reading (i.e., all images read by human readers without AI), AI-assisted reading (i.e., all images read by human readers with AI assistance as concurrent readers), and reading with AI triage (i.e., human reading of only those rendered abnormal by AI). Results: Of 5887 CXR images, 405 (6.9%) and 227 (3.9%) contained visible and clearly visible abnormalities, respectively. With AI-based triage, 42.9% (2354/5482) of normal CXR images were removed at the cost of erroneous removal of 3.5% (14/405) and 1.8% (4/227) of CXR images with visible and clearly visible abnormalities, respectively. In the diagnostic performance study, AI triage removed 41.6% (188/452) of normal images from the worklist without missing visible abnormalities and increased the specificity for some readers without decreasing sensitivity. Conclusion: This study suggests the feasibility of sorting and removing normal CXRs using AI with a tailored cut-off to increase efficiency and reduce the workload of radiologists.

• Biomolecules & Therapeutics
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• v.32 no.4
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• pp.481-491
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• 2024

Paxlovid is the first approved oral treatment for coronavirus disease 2019 and includes nirmatrelvir, a protease inhibitor targeting the main protease (M^pro) of SARS-CoV-2, as one of the key components. While some specific mutations emerged in M^pro were revealed to significantly reduce viral susceptibility to nirmatrelvir in vitro, there is no report regarding resistance to nirmatrelvir in patients and animal models for SARS-CoV-2 infection yet. We recently developed xenograft tumors derived from Calu-3 cells in immunodeficient mice and demonstrated extended replication of SARS-CoV-2 in the tumors. In this study, we investigated the effect of nirmatrelvir administration on SARS-CoV-2 replication. Treatment with nirmatrelvir after virus infection significantly reduced the replication of the parental SARS-CoV-2 and SARS-CoV-2 Omicron at 5 days post-infection (dpi). However, the virus titers were completely recovered at the time points of 15 and 30 dpi. The virus genomes in the tumors at 30 dpi were analyzed to investigate whether nirmatrelvir-resistant mutant viruses had emerged during the extended replication of SARS-CoV-2. Various mutations in several genes including ORF1ab, ORF3a, ORF7a, ORF7b, ORF8, and N occurred in the SARS-CoV-2 genome; however, no mutations were induced in the M^pro sequence by a single round of nirmatrelvir treatment, and none were observed even after two rounds of treatment. The parental SARS-CoV-2 and its sublineage isolates showed similar IC₅₀ values of nirmatrelvir in Vero E6 cells. Therefore, it is probable that inducing viral resistance to nirmatrelvir in vivo is challenging differently from in vitro passage.

• Tuberculosis and Respiratory Diseases
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• v.62 no.3
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• pp.192-196
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• 2007

Background: Right middle lobe syndrome (RMLS) is defined as transient or chronic and recurrent atelectasis of the right middle lobe. Although numerous conditions are associated with RMLS, there are very few recent reports in Korea. This study evaluated the causes of RMLS in a local tertiary hospitalover a period of 42 months. Method: Eighty-eight patients (M:F=64:22, mean age: $67.2{\pm}10.3years$), who had consistent chest radiography findings and underwent bronchoscopy in Gyeongsang University Hospital from January 2003 to July 2006, were enrolled in this study. The clinical characteristics and causes of RMLS in these patients were retrospectively reviewed. Results: The most common symptoms fo RMLS were cough, dyspnea and sputum. Tuberculosis was the most common cause (endobronchial tuberculosis in 22 and pulmonary tuberculosis in 1) The other causes were bronchial stenosis by benign fibrotic changes in 22 cases (25%), anthracofibrosis in 13 cases (14.8%), pneumonia in 11 cases (12.5%), lung cancer in 10 cases (11.4%), mucus impaction in 3 cases (3.4%), bronchiectasis in 2 cases (2.3%) and no demonstrable causes in 7 cases (8%). The bronchoscopy findings were mucosal edema with hyperemic changes in 38 cases (43.2%), mucosal edema with anthracotic pigmentation in 16 cases (18.2%), mucus impaction in 13 cases (14.8%), fibrotic stenosis in 13 cases (14.8%), a mass like lesion in 8 cases (9.1%), exudative necrotic material in 4 cases (4.5%), narrowing as a result of extrinsic compression in 2 cases (2.3%) and no demonstrable abnormalities in 12 cases (13.6%). Conclusion: Right middle lobe syndrome was observed more frequently in patients over the age of 65. The causes were mainly benign diseases with endobronchial tuberculosis being the most common.

• Tuberculosis and Respiratory Diseases
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• v.43 no.4
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• pp.590-599
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• 1996

Background : Bronchial artery embolization has been established as an effective means to control hemoptysis, especially in patients with decreased pulmonary function and those with advanced chronic obstructive pulmonary disease. We evaluated the effect of arterial embolization in immediate control of massive hemoptysis and investigated the clinical and angiographic characteristics and the course of patients with reccurrent hemoptysis after initial succeseful embolization. Another purpose of this study was to find predictive that cause rebleeding after bronchial artery embolization. Method : We reviewed 47 cases that underwent bronchial artery embolization for the management of massive hemoptysis, retrospectively. We analyzed angiographic findings in all cases before bronchial artery embolization and also reviewed the angiographic findings of patients that underwent additional bronchial artery embolization for the control of reccurrent hemoptysis to find the clauses of rebleeding. Results : 1) Underlying causes of hemoptysis were pulmonary tuberculosis(n=35), bronchiectasis(n=5), aspergilloma(n=2), lung cancer(n=2), pulmonary A-V malformation(n=1), and unknown cases(n=2). 2) Overal immediate success rate was 94%(n=44), an6 recurrence rate was 40%(n=19). 3) The prognostic factors such as bilaterality, systemic-pulmonary artery shunt, multiple feeding arteries and degree of neovascularity were not statistically correlated with rebleeding tendency (p value>0.05). 4) At additional bronchial artery embolization, Revealed recannalization of previous embolized arteries were 14/18cases(78%) and the presence of new deeding arteries was 8/18cases(44%). 5) The complications(31cases, 66%) such as fever, chest pain, cough, voiding difficulty, paralytic ileus, motor and sensory change of lower extremity, atelectasis and splenic infarction were occured. Conclusion : Recannalization of previous embolized arteries is the major cause of recurrence after bronchial artery embolization. Despite high recurrence rate of hemoptysis, bronchial artery embolization for management of massive hemoptysis is a effective and saute procedure in immediate bleeding control.

• Journal of the Korean Society of Radiology
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• v.4 no.4
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• pp.17-24
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• 2010

Hemoptysis which is comparatively common symptom in respiratory disease patients is a clinical symptom which has high risk of death in spite of many curative means. Bronchial tube embolization is a very useful medical procedure when hemoptysis does not stop for treatment of internal medicine or surgery and in addition to the purpose of instant hemostasis, for patients for whom surgical operation is impossible or for the purpose of gaining time to improve the state of the patient before surgical operation. In relation to this, this study is to know of the usefulness of bronchial tube artery embolization. The objects were 60 persons for whom bronchial tube artery embolizations are conducted because of large hemoptysis occurred from March 2007 to December 2009 in J hospital. They had large hemoptysis of 400ml or more per day and 200ml or more at a time or though the quantity of hemoptysis was less than 400ml they did not respond to the treatment of internal medicine for 10 days or longer. The average age was 60.5 years and cause diseases were tuberculosis, bronchiectasis, and pneumonia and lung cancer. Embolus parts were Rt bronchial artery 19 examples, Lt bronchial artery, both bronchial artery, Rt Intercostobronchial artery, and they were the case where embolization for many blood vessels were simultaneously carried out. As embolus materials, PVA (conteour) and microcoil were used. In 76.6% of 60 persons of patients hemorrhage stopped with the lapse of time after the procedure and in 4 examples (6.6) re-embolization was carried out due to re-bleeding after the procedure. Bronchial tube artery embolization has high early success rate and effectively controls hemoptysis in the treatment of hemoptysis and is an effective emergency remedy for hemorrhage due to large hemoptysis and will be a good medical procedure which reduces death rate. In addition, primarily if it is conducted together with the treatment of internal medicine it will be, as an effective curative means for hemorrhage due to large hemoptysis, a good mediate radial rays medical procedure which reduces death rate.

• Tuberculosis and Respiratory Diseases
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• v.47 no.2
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• pp.209-217
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• 1999

Backgrounds: To investigate the role of CT as a screening tool and to compare the diagnostic accuracy with that of the fiberoptic bronchoscopy (FOB) in evaluating the causes of hemoptysis. Methods: The retrospective review of plain chest radiograph, CT and FOB was done in 72 patients with hemoptysis. The diagnosis were confirmed by histology (n=33), bacterial culture (n=6), cytology (n=3), serology (n=2), skin test (n= 1), clinical response (n=5), and airway disease mainly by HRCT (n=22). Results: The causes of hemoptysis were shown to be lung cancer (n=29), bronchiectasis (n=19), tuberculosis (n=12), aspergilloma (n=5), invasive aspergillosis (n=l), COPD (n=3) and others (n=3). The sensitivity was 100% and 91,7% by CT and FOB respectively. The diagnostic compatibility was 95.8% and 59.7% by CT and FOB respectively. The diagnostic compatibility in cases with central airway disease was 96.3% and 100 % in CT and FOB. In parenchymal disease, CT and FOB showed 91.3 % and 43.5 % of compatibility, respectively. airway disease, CT and FOB showed 100% and 31.8% compatibility, respectively. That is to say, CT has higher sensitivity and diagnostic compatibility than FOB for identifying the causes of hemoptysis, and is more helpful for patients with hemoptysis from parenchymal or airway disease. FOB had the advantage in obtaining histologic, cytologic and bacteriologic diagnosis with biopsy or washing Conclusion: CT should be used as the screening method before performing FOB for patients with hemoptysis who have normal or nonspecific findings or peripheral airway disease in plain chest radiograph.

• The Korean Journal of Nuclear Medicine Technology
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• v.15 no.1
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• pp.10-16
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• 2011

Purpose: The partial volume effect occurs because of limit of the spatial resolution. It makes partial loss of intensity and causes SUV to be lower than it should actually be. So the purpose of this study is to calculate recovery coefficient for correcting PVE from phantom study and to compare before and after SUV correction applying to PET/CT examination. Materials and Methods: The flangeless Esser PET phantom consisting of four hot cylinders was used for this study. All of the hot cylinders were filled with FDG solution of 20.72 MBq per 1000 ml, and the phantom background was filled with FDG solution of different concentrations (33.30, 22.20, 16.65 MBq per 6440 ml) to yield H/B ratios of around 4:1, 6:1 and 8:1. Using the Biograph Truepoint 40(SIEMENS, Germany), we applied recovery coefficient method to 30 patients who were diagnosed with lung cancer after PET/CT exam. And then we analyzed and compared SUV before and after correcting partial volume effect. Results: The smaller the diameter of hot cylinder becomes, the more recovery coefficient decreased. When we applied recovery coefficient to clinical patients and compared SUV before and after correcting PVE, before the correction all lesions gave an average max SUV of 7.83. And after the correction, the average max SUV increases to 10.31. The differences in the max SUV between before and after correction were analyzed by paired t test. As a result, there were statistically significant differences (t=7.21, p=0.000). Conclusion: The SUV for quantification should be measured precisely to give consistent information of tumor uptake. But PVE is one of factors that causes SUV to be lower and to be underestimated. We can correct this PVE and calculate corrected SUV using the recovery coefficient from phantom study. And if we apply this correction method to clinical patients, we can finally assess and provide quantitative analysis more accurately.

• Journal of Chest Surgery
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• v.40 no.10
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• pp.674-679
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• 2007

Background: Surgical resection is accepted widely as the standard therapy for complete resectable pulmonary metastases. The number of cases of pulmonary metastasectomy and its survival rate is increasing due to the development of the therapeutic modalities. We attempted to analyze the survival rate and prognosis factors of pulmonary metastasectomy during the last 10 years. Material and Method: We retrospectively analyzed the data of 89 patients who underwent 96 procedures of pulmonary metastasectomy between January 1996 and December 2005. The factors that may influence the long term prognosis such as completeness of resection, the type of primary cancer, the disease-free interval, the number and size of metastasis and the laterality were investigated. Result: There was no operative mortality. The mean disease free interval (DFI) was $29.6{\pm}27.9$ months and there were 3 cases of synchronous metastasis (3.4%). The overall 3, 5 and 10 year survival rate was 52.5%, 32.1% and 20.7%, respectively. The median survival time was 38 months. The 5-year survival rate according to the IRLM appraisal was 63.5%, 33.3%, 22.1% and 0% for stage I, II, III and IV, respectively Univariate analysis showed a better prognosis for patients with a disease free interval of 36 months or more, unilateral metastasis and 4 or less metastases. Conclusion: The survival rate for completely resectable pulmonary metastasectomy was favorable. The disease free interval, laterality and the number of metastasis were the prognosis factors.