Radiation Dose Reduction of Chest CT with Iterative Reconstruction in Image Space - Part I: Studies on Image Quality Using Dual Source CT

황혜전,서준범,이진성,송재우,김성수,이현주,임채훈 대한영상의학회 2012 Korean Journal of Radiology Vol.13 No.6

Objective: To determine whether the image quality (IQ) is improved with iterative reconstruction in image space (IRIS), and whether IRIS can be used for radiation reduction in chest CT. Materials and Methods: Standard dose chest CT (SDCT) in 50 patients and low dose chest CT (LDCT) in another 50 patients were performed, using a dual-source CT, with 120 kVp and same reference mAs (50 mAs for SDCT and 25 mAs for LDCT) employed to both tubes by modifying a dual-energy scan mode. Full-dose data were obtained by combining the data from both tubes and half-dose data were separated from a single tube. These were reconstructed by using a filtered back projection (FBP) and IRIS: full-dose FBP (F-FBP); full-dose IRIS (F-IRIS); half-dose FBP (H-FBP) and half-dose IRIS (H-IRIS). Objective noise was measured. The subjective IQ was evaluated by radiologists for the followings: noise, contrast and sharpness of mediastinum and lung. Results: Objective noise was significantly lower in H-IRIS than in F-FBP (p < 0.01). In both SDCT and LDCT, the IQ scores were highest in F-IRIS, followed by F-FBP, H-IRIS and H-FBP, except those for sharpness of mediastinum, which tended to be higher in FBP. When comparing CT images between the same dose and different reconstruction (F-IRIS/F-FBP and H-IRIS/H-FBP) algorithms, scores tended to be higher in IRIS than in FBP, being more distinct in half-dose images. However, despite the use of IRIS, the scores were lower in H-IRIS than in F-FBP. Conclusion: IRIS generally helps improve the IQ, being more distinct at the reduced radiation. However, reduced radiation by half results in IQ decrease even when using IRIS in chest CT. Objective: To determine whether the image quality (IQ) is improved with iterative reconstruction in image space (IRIS), and whether IRIS can be used for radiation reduction in chest CT. Materials and Methods: Standard dose chest CT (SDCT) in 50 patients and low dose chest CT (LDCT) in another 50 patients were performed, using a dual-source CT, with 120 kVp and same reference mAs (50 mAs for SDCT and 25 mAs for LDCT) employed to both tubes by modifying a dual-energy scan mode. Full-dose data were obtained by combining the data from both tubes and half-dose data were separated from a single tube. These were reconstructed by using a filtered back projection (FBP) and IRIS: full-dose FBP (F-FBP); full-dose IRIS (F-IRIS); half-dose FBP (H-FBP) and half-dose IRIS (H-IRIS). Objective noise was measured. The subjective IQ was evaluated by radiologists for the followings: noise, contrast and sharpness of mediastinum and lung. Results: Objective noise was significantly lower in H-IRIS than in F-FBP (p < 0.01). In both SDCT and LDCT, the IQ scores were highest in F-IRIS, followed by F-FBP, H-IRIS and H-FBP, except those for sharpness of mediastinum, which tended to be higher in FBP. When comparing CT images between the same dose and different reconstruction (F-IRIS/F-FBP and H-IRIS/H-FBP) algorithms, scores tended to be higher in IRIS than in FBP, being more distinct in half-dose images. However, despite the use of IRIS, the scores were lower in H-IRIS than in F-FBP. Conclusion: IRIS generally helps improve the IQ, being more distinct at the reduced radiation. However, reduced radiation by half results in IQ decrease even when using IRIS in chest CT.

Radiation Dose Reduction of Chest CT with Iterative Reconstruction in Image Space - Part II: Assessment of Radiologists’ Preferences Using Dual Source CT

황혜전,서준범,이진성,송재우,김성수,이현주,임채훈 대한영상의학회 2012 Korean Journal of Radiology Vol.13 No.6

Objective: To evaluate the impact of radiation dose and reconstruction algorithms on radiologists’ preferences, and whether an iterative reconstruction in image space (IRIS) can be used for dose reduction in chest CT. Materials and Methods: Standard dose chest CT (SDCT) in 50 patients and low dose chest CT (LDCT) in another 50 patients were performed, using a dual-source CT, with 120 kVp and same reference mAs (50 mAs for SDCT and 25 mAs for LDCT) employed to both tubes by modifying the dual-energy scan mode. Full-dose data were obtained by combining the data from both tubes and half-dose data were separated from one tube. These were reconstructed by using a filtered back projection (FBP) and IRIS: full-dose FBP (F-FBP); full-dose IRIS (F-IRIS); half-dose FBP (H-FBP) and half-dose IRIS (H-IRIS). Ten H-IRIS/F-IRIS, 10 H-FBP/H-IRIS, 40 F-FBP/F-IRIS and 40 F-FBP/H-IRIS pairs of each SDCT and LDCT were randomized. The preference for clinical usage was determined by two radiologists with a 5-point-scale system for the followings: noise, contrast, and sharpness of mediastinum and lung. Results: Radiologists preferred IRIS over FBP images in the same radiation dose for the evaluation of the lungs in both SDCT (p = 0.035) and LDCT (p < 0.001). When comparing between H-IRIS and F-IRIS, decreased radiation resulted in decreased preference. Observers preferred H-IRIS over F-FBP for the lungs in both SDCT and LDCT, even with reduced radiation dose by half in IRIS image (p < 0.05). Conclusion: Radiologists’ preference may be influenced by both radiation dose and reconstruction algorithm. According to our preliminary results, dose reduction at 50% with IRIS may be feasible for lung parenchymal evaluation. Objective: To evaluate the impact of radiation dose and reconstruction algorithms on radiologists’ preferences, and whether an iterative reconstruction in image space (IRIS) can be used for dose reduction in chest CT. Materials and Methods: Standard dose chest CT (SDCT) in 50 patients and low dose chest CT (LDCT) in another 50 patients were performed, using a dual-source CT, with 120 kVp and same reference mAs (50 mAs for SDCT and 25 mAs for LDCT) employed to both tubes by modifying the dual-energy scan mode. Full-dose data were obtained by combining the data from both tubes and half-dose data were separated from one tube. These were reconstructed by using a filtered back projection (FBP) and IRIS: full-dose FBP (F-FBP); full-dose IRIS (F-IRIS); half-dose FBP (H-FBP) and half-dose IRIS (H-IRIS). Ten H-IRIS/F-IRIS, 10 H-FBP/H-IRIS, 40 F-FBP/F-IRIS and 40 F-FBP/H-IRIS pairs of each SDCT and LDCT were randomized. The preference for clinical usage was determined by two radiologists with a 5-point-scale system for the followings: noise, contrast, and sharpness of mediastinum and lung. Results: Radiologists preferred IRIS over FBP images in the same radiation dose for the evaluation of the lungs in both SDCT (p = 0.035) and LDCT (p < 0.001). When comparing between H-IRIS and F-IRIS, decreased radiation resulted in decreased preference. Observers preferred H-IRIS over F-FBP for the lungs in both SDCT and LDCT, even with reduced radiation dose by half in IRIS image (p < 0.05). Conclusion: Radiologists’ preference may be influenced by both radiation dose and reconstruction algorithm. According to our preliminary results, dose reduction at 50% with IRIS may be feasible for lung parenchymal evaluation.

췌장에 생긴 전이성 혈관주위세포종의 영상 소견

황혜전,변재호,박성호,이문규 대한영상의학회 2007 대한영상의학회지 Vol.57 No.3

Hemangiopericytoma of the pancreas has rarely been described, and its radiological findings have never been described in the radiological literature. We report a case of a metastatic hemangiopericytoma involving the pancreas in a 48-year-old woman. CT, MR, and angiography showed three, well-demarcated, heterogeneously enhancing masses with necrosis and hemorrhage in the pancreas. 췌장의 혈관주위세포종은 매우 드물게 보고되었으며, 그 영상소견은 영상의학지에 보고된 경우가 없다. 저자들은 48세 여자 환자에서 췌장에 생긴 전이성 혈관주위세포종의 영상소견을 보고하고자 한다. 복부전산단층촬영, 자기공명영상, 그리고 혈관조영술에서 췌장에 세 개의 경계가 좋고 불균일한 조영증강을 보이는 종괴로 괴사와 출혈을 동반하였다.

MPEG-4 Shape Decoder의 적합성 검사

황혜전,박인수,박수현,이병욱 한국통신학회 2000 韓國通信學會論文誌 Vol.25 No.6

MPEG-4 영상압축 방식은 객체지향적이다. 기존의 H.261, MPEG-1, MPEG-2에서 화면 전체를 부호화 해주는 것과 달리 MPEG-4에서는 한 화면을 물체, 배경 등 여러 객체들로 나누어 각각의 객체를 따로 부호화한다. 이렇게 전송된 객체들은 수신 단말기에서 다시 합성하여 완성된 화면으로 보여준다. MPEG-4의 형상 부호화는 화면에서 visual 객체에 해당하는 부분만을 부호화 해주는 부분이다. 본 논문에서는 MPEG-4 디코더가 형상 복호화의 표준 규격을 따르는지를 시험하는 방법을 제안한다. 본 논문은 BAB type을 결정하는 mode 복호화의 모든 경우와 Context-based Arithmetic 복호화의 Context computation에 대한 모든 경우에 대해 확인하는 방법을 제안하였다. MPEG-4 visual coding is an object-based system. The current video coding standards, H.261, MPEG-1, and MPEG-2 encode frame by frame. On the other hand, MPEG-4 separately encodes several objects, such as video objects and audio objects, in the same frame. Each transmitted object is decoded and composed in one frame. Shape coding is a process of coding visual objects in a frame. In this paper we present conformance test method for MPEG-4 shape decoders. This paper reviews the basic shape decoding standard, and proposes conformance test methods for BAB type decoder, and CAE decoder for intra and inter VOPs. Our test generates all possible cases of shape motion vector difference and context.

대학도서관 무선인터넷 서비스에 관한 연구

이두영,황혜전 한국정보관리학회 2002 정보관리학회지 Vol.19 No.4

The purpose of the study is to suggest and measure the ways to activate the use of wireless internet services in university libraries. For this, 1 reviewed the concepts and characteristics of wireless internet and investigated both local and foreign cases on wireless internet service of university libraries, library users'''' usage status, and their demands. Based on the case study and survey results, I suggest the strategic consideration and active publicity of university libraries, the introduction of the services students more prefer, the development of differentiated menus from ordinary wire internet services, and the consistent financial support of the university authority. 본 연구는 무선인터넷의 개념 및 특성을 고찰하고 도서관 무선인터넷 서비스의 국내외 현황과 이용자들의 이용실태 및 요구사항 등을 분석하였다. 도서관 무선인터넷 서비스가 활성화되기 위해서는 도서관의 전략적인 계획 및 홍보, 학생들의 선호하는 유형의 무선인터넷 서비스의 우선 도입, 무선인터넷 요금과 직관되는 무선인터넷 접속 시간을 줄이기 위한 서비스 메뉴의 엄선, 그리고 마지막으로 대학 당국의 일관성 있는 재정 지원이 필요함을 제안하였다.

Ultrasonographic Findings of Epipericardial Fat Necrosis: A Case Report

박찬영,황혜전,이관섭,이인재,박경하 대한영상의학회 2016 대한영상의학회지 Vol.74 No.4

Epipericardial fat necrosis (EFN) is an infrequent cause of acute chest pain. In rare cases like these, conservative treatment is necessary. Clinically, EFN may mimic emergent cardiopulmonary conditions, such as acute myocardial infarction. Computed tomography (CT) and magnetic resonance imaging characteristics of EFN is well described as encapsulated fatty lesion with perilesional soft tissue strands and thickening of adjacent pericardium in the epipericardial area. For confirmation of the diagnosis, involution of this lesion on follow-up is important. We present a case of EFN observed with ultrasonography (USG). This lesion was shown as a well-defined ovoid shaped mass with heterogeneous echogenicity in the left side of cardiophrenic space on USG. There was no color flow on Doppler USG. Follow-up USG and CT revealed decrease in the size of the lesion.

Assessment of Perfusion Pattern and Extent of Perfusion Defect on Dual-Energy CT Angiography: Correlations between the Causes of Pulmonary Hypertension and Vascular Parameters

김은영,서준범,오상영,이충욱,황혜전,이상민,이영경 대한영상의학회 2014 Korean Journal of Radiology Vol.15 No.2

Objective: To assess perfusion patterns on a dual-energy pulmonary CT angiography (DECTA) of pulmonary hypertension (PHT) with variable causes and to assess whether the extent of perfusion defect can be used in the severity assessment of PHT. Materials and Methods: Between March 2007 and February 2011, DECTA scans of 62 consecutive patients (24 men, 38 women; mean age, 58.5 ± 17.3 [standard deviation] years; range, 19–87 years) with PHT were retrospectively included with following inclusion criteria; 1) absence of acute pulmonary thromboembolism, 2) maximal velocity of tricuspid regurgitation jet (TR Vmax) above 3 m/s on echocardiography performed within one week of the DECTA study. Perfusion patterns of iodine map were divided into normal (NL), diffuse heterogeneously decreased (DH), multifocal geographic and multiple peripheral wedging patterns. The extent of perfusion defects (PD), the diameter of main pulmonary artery (MPA) and the ratio of ascending aorta diameter/MPA (aortopulmonary ratio, APR) were measured. Pearson correlation analysis was performed between TR Vmax on echocardiography and CT imaging parameters. Results: Common perfusion patterns of primary PHT were DH (n = 15) and NL (n = 12). The perfusion patterns of secondary PHT were variable. On the correlation analysis, in primary PHT, TR Vmax significantly correlated with PD, MPA and APR (r = 0.52, r = 0.40, r = -0.50, respectively, all p < 0.05). In secondary PHT, TR Vmax significantly correlated with PD and MPA (r = 0.38, r = 0.53, respectively, all p < 0.05). Conclusion: Different perfusion patterns are observed on DECTA of PHT according to the causes. PD and MPA are significantly correlated with the TR Vmax.

소아에서 발생한 원발성 복막수염: 2예 보고

전준영,이관섭,김민정,하홍일,김은수,문진희,황혜전 대한초음파의학회 2013 ULTRASONOGRAPHY Vol.32 No.4

Primary epiploic appendagitis (PEA) is a condition that results from spontaneoustorsion, ischemia, or inflammation of an epiploic appendage. This condition is manifestedby localized abdominal pain and tenderness, which is often mistaken for diverticulitisor appendicitis in the adult population. PEA is a self-limiting disease, and differentialdiagnosis with surgical condition is important in order to prevent unnecessarysurgery. Although it is commonly reported in adults, it is rarely reported in the pediatricpopulation. We report on the radiologic findings of two cases of PEA in a 12- and a17-year-old boy, focusing on sonographic findings. 원발성 복막수염은 복막수의 염전, 허혈, 또는 염증이 자발적으로 일어나는 질환으로 특징적인 국소적인 복통 및 압통을 호소하기 때문에 성인에서는 게실염 또는 급성충수돌기염 등으로 오인되기 쉽다. 원발성 복막수염은 특별한치료 없이 저절로 치유되므로 급성복증 환자에서 외과적수술을 요하는 질환과의 감별이 중요하다. 성인에서 발병한 원발성 복막수염에 대해서는 많은 보고가 있으나, 소아에서의 보고는 매우 드물다. 저자들은 12세, 17세 남아에서 발생한 두 예의 원발성 복막수염의 영상의학적 소견에대해 초음파 소견을 중심으로 보고하고자 한다.

Partial Anomalous Pulmonary Venous Return via a Levoatriocardinal Vein in Association with Rheumatic Mitral Stenosis: MR Demonstration and Successful Surgical Repair

현동호,채은진,서준범,강준원,도경현,이충욱,이현주,황혜전,임태환 대한영상의학회 2010 대한영상의학회지 Vol.63 No.4

The preoperative evaluation of the hemodynamics associated with PAPVR and rheumatic mitral valve stenosis is necessary for successful surgical treatment, even though the incidence rate is rare. The purpose of this case report is to present the usefulness of CT and MRI for diagnosing rheumatic mitral stenosis and partial anomalous pulmonary venous connection to the left innominate vein accompanied by the presence of the levoatriocardinal vein and evaluating its flow dynamics.