Usefulness of the CAD System for Detecting Pulmonary Nodule in Real Clinical Practice

송경두,정명진,김희철,정선영,이경수 대한영상의학회 2011 Korean Journal of Radiology Vol.12 No.2

Objective: We wanted to evaluate the usefulness of the computer-aided detection (CAD) system for detecting pulmonary nodules in real clinical practice by using the CT images. Materials and Methods: Our Institutional Review Board approved our retrospective study with a waiver of informed consent. This study included 166 CT examinations that were performed for the evaluation of pulmonary metastasis in 166 patients with colorectal cancer. All the CT examinations were interpreted by radiologists and they were also evaluated by the CAD system. All the nodules detected by the CAD system were evaluated with regard to whether or not they were true nodules, and they were classifi ed into micronodules (MN, diameter < 4 mm) and signifi cant nodules (SN, 4 ≤ diameter ≤ 10 mm). The radiologic reports and CAD results were compared. Results: The CAD system helped detect 426 nodules; 115 (27%) of the 426 nodules were classifi ed as true nodules and 35 (30%) of the 115 nodules were SNs, and 83 (72%) of the 115 were not mentioned in the radiologists’ reports and three (4%) of the 83 nodules were non-calcifi ed SNs. One of three non-calcifi ed SNs was confi rmed as a metastatic nodule. According to the radiologists’ reports, 60 true nodules were detected, and 28 of the 60 were not detected by the CAD system. Conclusion: Although the CAD system missed many SNs that are detected by radiologists, it helps detect additional nodules that are missed by the radiologists in real clinical practice. Therefore, the CAD system can be useful to support a radiologist’s detection performance.

Current status of deep learning applications in abdominal ultrasonography

송경두 대한초음파의학회 2021 ULTRASONOGRAPHY Vol.40 No.2

Deep learning is one of the most popular artificial intelligence techniques used in the medical field. Although it is at an early stage compared to deep learning analyses of computed tomography or magnetic resonance imaging, studies applying deep learning to ultrasound imaging have been actively conducted. This review analyzes recent studies that applied deep learning to ultrasound imaging of various abdominal organs and explains the challenges encountered in these applications.

딥러닝 알고리즘 개발과정을 통해 본 영상의학분야에서 딥러닝의 최신 경향

송경두,김명찬,도신호 대한영상의학회 2019 대한영상의학회지 Vol.80 No.2

최근 인공지능은 지각정보를 해석하는데 있어 상당한 진보를 이루었으며, 이를 통해 기계는매우 복잡한 데이터를 보다 잘 해석할 수 있게 되었다. 최근 몇 년간 딥러닝 기술로 대표되는인공지능의 의료 및 생물의학 연구분야로의 적용이 기하급수적으로 증가하고 있다. 이번 기고문에서는 의료영상분야의 딥러닝 알고리즘 개발 단계를 주제선정, 데이터 수집, 데이터 탐색 및 정제, 알고리즘 개발, 알고리즘 평가 그리고 임상적용의 단계로 나누어 설명하고, 각각의 단계에서 최신의 동향을 소개하고자 한다 Recently, considerable progress has been made in interpreting perceptual information through artificial intelligence, allowing better interpretation of highly complex data by machines. Furthermore, the applications of artificial intelligence, represented by deep learning technology, to the fields of medical and biomedical research are increasing exponentially. In this article, we will explain the stages of deep learning algorithm development in the field of medical imaging, namely topic selection, data collection, data exploration and refinement, algorithm development, algorithm evaluation, and clinical application; we will also discuss the latest trends for each stage.

Pulmonary Cryptococcosis: Imaging Findings in 23 Non-AIDS Patients

송경두,이경수,정만표,권오정,김태성,이진아,정명진 대한영상의학회 2010 Korean Journal of Radiology Vol.11 No.4

Objective: We aimed to review the patterns of lung abnormalities of pulmonary cryptococcosis on CT images, position emission tomography (PET) findings of the disease, and the response of lung abnormalities to the therapies in non-AIDS patients. Materials and Methods: We evaluated the initial CT (n = 23) and 18F-fluorodeoxyglucose (FDG) PET (n = 10), and follow-up (n = 23) imaging findings of pulmonary cryptococcosis in 23 non-AIDS patients. Lung lesions were classified into five patterns at CT: single nodular, multiple clustered nodular, multiple scattered nodular, mass-like, and bronchopneumonic patterns. The CT pattern analyses, PET findings, and therapeutic responses were recorded. Results: A clustered nodular pattern was the most prevalent and was observed in 10 (43%) patients. This pattern was followed by solitary pulmonary nodular (n = 4, 17%), scattered nodular (n = 3, 13%), bronchopneumonic (n = 2, 9%), and single mass (n = 1, 4%) patterns. On PET scans, six (60%) of 10 patients showed higher FDG uptake and four (40%) demonstrated lower FDG uptake than the mediastinal blood pool. With specific treatment of the disease, a complete clearance of lung abnormalities was noted in 15 patients, whereas a partial response was noted in seven patients. In one patient where treatment was not performed, the disease showed progression. Conclusion: Pulmonary cryptococcosis most commonly appears as clustered nodules and is a slowly progressive and slowly resolving pulmonary infection. In two-thirds of patients, lung lesions show high FDG uptake, thus simulating a possible malignant condition.

Basics of Deep Learning: A Radiologist’s Guide to Understanding Published Radiology Articles on Deep Learning

도신호,송경두,정주원 대한영상의학회 2020 Korean Journal of Radiology Vol.21 No.1

Artificial intelligence has been applied to many industries, including medicine. Among the various techniques in artificial intelligence, deep learning has attained the highest popularity in medical imaging in recent years. Many articles on deep learning have been published in radiologic journals. However, radiologists may have difficulty in understanding and interpreting these studies because the study methods of deep learning differ from those of traditional radiology. This review article aims to explain the concepts and terms that are frequently used in deep learning radiology articles, facilitating general radiologists’ understanding.

Added Value of Contrast-Enhanced Ultrasound on Biopsies of Focal Hepatic Lesions Invisible on Fusion Imaging Guidance

강태욱,이민우,송경두,김미미,김승수,김성현,하상윤 대한영상의학회 2017 Korean Journal of Radiology Vol.18 No.1

Objective: To assess whether contrast-enhanced ultrasonography (CEUS) with Sonazoid can improve the lesion conspicuity and feasibility of percutaneous biopsies for focal hepatic lesions invisible on fusion imaging of real-time ultrasonography (US) with computed tomography/magnetic resonance images, and evaluate its impact on clinical decision making. Materials and Methods: The Institutional Review Board approved this retrospective study. Between June 2013 and January 2015, 711 US-guided percutaneous biopsies were performed for focal hepatic lesions. Biopsies were performed using CEUS for guidance if lesions were invisible on fusion imaging. We retrospectively evaluated the number of target lesions initially invisible on fusion imaging that became visible after applying CEUS, using a 4-point scale. Technical success rates of biopsies were evaluated based on histopathological results. In addition, the occurrence of changes in clinical decision making was assessed. Results: Among 711 patients, 16 patients (2.3%) were included in the study. The median size of target lesions was 1.1 cm (range, 0.5–1.9 cm) in pre-procedural imaging. After CEUS, 15 of 16 (93.8%) focal hepatic lesions were visualized. The conspicuity score was significantly increased after adding CEUS, as compared to that on fusion imaging (p < 0.001). The technical success rate of biopsy was 87.6% (14/16). After biopsy, there were changes in clinical decision making for 11 of 16 patients (68.8%). Conclusion: The addition of CEUS could improve the conspicuity of focal hepatic lesions invisible on fusion imaging. This dual guidance using CEUS and fusion imaging may affect patient management via changes in clinical decision-making.

New Radiofrequency Device to Reduce Bleeding after Core Needle Biopsy: Experimental Study in a Porcine Liver Model

임상혁,임현철,이민우,송경두,강태욱,김영선,임효근 대한영상의학회 2017 Korean Journal of Radiology Vol.18 No.1

Objective: To evaluate the in vivo efficiency of the biopsy tract radiofrequency ablation for hemostasis after core biopsy of the liver in a porcine liver model, including situations with bleeding tendency and a larger (16-gauge) core needle. Materials and Methods: A preliminary study was performed using one pig to determine optimal ablation parameters. For the main experiment, four pigs were assigned to different groups according to heparinization use and biopsy needle caliber. In each pig, 14 control (without tract ablation) and 14 experimental (tract ablation) ultrasound-guided core biopsies were performed using either an 18- or 16-gauge needle. Post-biopsy bleeding amounts were measured by soaking up the blood for five minutes. The results were compared using the Mann-Whitney U test. Results: The optimal parameters for biopsy tract ablation were determined as a 2-cm active tip electrode set at 40-watt with a tip temperature of 70–80°C. The bleeding amounts in all experimental groups were smaller than those in the controls; however they were significant in the non-heparinized pig biopsied with an 18-gauge needle and in two heparinized pigs (p < 0.001). In the heparinized pigs, the mean blood loss in the experimental group was 3.5% and 13.5% of the controls biopsied with an 18- and 16-gauge needle, respectively. Conclusion: Radiofrequency ablation of hepatic core biopsy tract ablation may reduce post-biopsy bleeding even under bleeding tendency and using a larger core needle, according to the result from in vivo porcine model experiments.

Percutaneous radiofrequency ablation of hepatocellular carcinoma in a recent cohort at a tertiary cancer center: incidence and factors associated with major complications and unexpected hospitalization events

Min Geun Jo,이민우,안수현,강태욱,송경두,Cha Dong Ik,Min Ji Hye,임현철 대한초음파의학회 2023 ULTRASONOGRAPHY Vol.42 No.1

Purpose: This study aimed to assess the incidence of and factors associated with major complications, delayed discharge, and emergency room (ER) visits or readmission after percutaneous radiofrequency ablation (RFA) for single hepatocellular carcinoma (HCC) <3 cm in a recent cohort at a tertiary cancer center. Methods: A total of 188 patients with treatment-naïve single HCCs <3 cm who underwent RFA between January 2018 and April 2021 were included in the analysis. Univariable and multivariable logistic regression analyses were performed to identify the factors associated with major complications, delayed discharge, and ER visits or readmission. Local tumor progression (LTP) and overall survival were estimated using the Kaplan-Meier method and Cox proportional-hazards regression analysis. Results: Major complications occurred in 3.2% (6/188) of the patients. The longest diameter of the ablation zone was significantly larger in patients with major complications (P=0.023). Delayed discharge occurred in 5.8% (9/188) of the patients, for which albumin-bilirubin grade 3 was identified as an important determinant. No variables other than major complications were significantly associated with ER visits or readmission, which occurred in 7.0% (13/188) of the patients. Major complications, delayed discharge, and ER visits or readmission were not substantially related to the post-treatment outcomes of LTP and overall survival. Conclusion: This study confirmed RFA as a highly safe procedure for single HCCs <3 cm, despite the rapidly changing RFA techniques in the most recent cohort. A large ablation zone and poor liver function were predictors of major complications and delayed discharge, respectively.

Laparoscopic radiofrequency ablation versus percutaneous radiofrequency ablation for subphrenic hepatocellular carcinoma

곽민환,이민우,Ko Seong Eun,임현철,강태욱,송경두,김종만,Choi Gyu Seong 대한초음파의학회 2022 ULTRASONOGRAPHY Vol.41 No.3

Purpose: Radiofrequency ablation is a curative treatment option for very early-stage or earlystage hepatocellular carcinoma (HCC). However, percutaneous radiofrequency ablation (PRFA) for subphrenic tumors is technically challenging. Laparoscopic radiofrequency ablation (LRFA) has been used to overcome this disadvantage. This study compared the treatment outcomes between LRFA and PRFA for subphrenic HCC.Methods: This retrospective study screened patients who underwent PRFA or LRFA for subphrenic HCC between 2013 and 2018. Therapeutic outcomes, including local tumor progression (LTP), intrahepatic distant recurrence (IDR), extrahepatic metastasis (EM), disease-free survival (DFS), and overall survival (OS), were compared between the two groups.Results: Thirty patients in the PRFA group and 23 patients in the LRFA group were included. LTP was observed in six patients in the PRFA group (20%), but in no patients in the LRFA group. The cumulative LTP rates at 1, 3, and 5 years were 3.7%, 23.4%, and 23.4%, respectively, in the PRFA group and 0.0% in the LRFA group (P=0.015). The IDR, EM, and DFS rates were not significantly different between the two groups (P=0.304, P=0.175, and P=0.075, respectively). The OS rates at 1, 3, and 5 years were 96.6%, 85.7%, and 71.6%, respectively, in the PRFA group and 100%, 95.7%, and 95.7%, respectively, in the LRFA group (P=0.049).Conclusion: LRFA demonstrated better therapeutic outcomes than did PRFA for subphrenic tumors in terms of LTP and OS. Therefore, LRFA can be considered as the first-line treatment option for subphrenic HCC.

Percutaneous radiofrequency ablation for hepatic metastasis of colorectal cancer: assessment of tumor visibility and the feasibility of the procedure with planning ultrasonography

Bae Jeong Woo,이민우,강태욱,송경두,차동익,Min Ji Hye,임현철 대한초음파의학회 2022 ULTRASONOGRAPHY Vol.41 No.1

Purpose: The aim of this study was to assess the incidence and causes of percutaneous radiofrequency ablation (RFA) infeasibility in cases of metastatic colorectal cancer and to evaluate factors affecting the invisibility of the tumor on planning ultrasonography (US). Methods: This study screened 386 patients who underwent planning US using fusion imaging and/or contrast-enhanced US for percutaneous RFA for suspected metastatic colorectal cancer between January 2013 and December 2020, from whom 136 patients with a single hepatic metastasis from colorectal cancer measuring <3 cm were included. The factors related to the infeasibility of percutaneous RFA were investigated. Univariate and multivariate analyses were performed to assess the factors associated with tumor invisibility on planning US. Results: Among the 136 patients, percutaneous RFA was considered infeasible in 24.3% (33/136) due to a high risk of the heat-sink effect caused by the abutment of a large vessel (n=12), an inconspicuous tumor on planning US (n=11), a high risk of collateral thermal damage to an adjacent organ (n=8), and the absence of a safe electrode path (n=2). In univariate and multivariate analyses, tumor size was a statistically significant factor affecting invisibility on planning US (P=0.003 and P=0.018, respectively). Conclusion: Percutaneous RFA was infeasible in approximately one-fourth of patients with metastatic colorectal cancer. The reason for the infeasibility was mainly an unfavorable tumor location and invisibility on planning US. Small tumor size was the sole significant factor affecting the invisibility of hepatic metastases on planning US. Purpose: The aim of this study was to assess the incidence and causes of percutaneous radiofrequency ablation (RFA) infeasibility in cases of metastatic colorectal cancer and to evaluate factors affecting the invisibility of the tumor on planning ultrasonography (US).Methods: This study screened 386 patients who underwent planning US using fusion imaging and/or contrast-enhanced US for percutaneous RFA for suspected metastatic colorectal cancer between January 2013 and December 2020, from whom 136 patients with a single hepatic metastasis from colorectal cancer measuring <3 cm were included. The factors related to the infeasibility of percutaneous RFA were investigated. Univariate and multivariate analyses were performed to assess the factors associated with tumor invisibility on planning US.Results: Among the 136 patients, percutaneous RFA was considered infeasible in 24.3% (33/136) due to a high risk of the heat-sink effect caused by the abutment of a large vessel (n=12), an inconspicuous tumor on planning US (n=11), a high risk of collateral thermal damage to an adjacent organ (n=8), and the absence of a safe electrode path (n=2). In univariate and multivariate analyses, tumor size was a statistically significant factor affecting invisibility on planning US (P=0.003 and P=0.018, respectively).Conclusion: Percutaneous RFA was infeasible in approximately one-fourth of patients with metastatic colorectal cancer. The reason for the infeasibility was mainly an unfavorable tumor location and invisibility on planning US. Small tumor size was the sole significant factor affecting the invisibility of hepatic metastases on planning US.