Publications by authors named "Hye Jeon Hwang"

39 Publications

Lobar Ventilation in Patients with COPD Assessed with the Full-Scale Airway Network Flow Model and Xenon-enhanced Dual-Energy CT.

Radiology 2021 01 24;298(1):201-209. Epub 2020 Nov 24.

From the School of Mechanical, Electrical and Manufacturing Engineering, Loughborough University, Loughborough LE11 3TU, England (M.K.); Healthy Science Institute, Ege University, Izmir, Turkey (O.D.); Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea (H.J.H., J.B.S.); Department of Oncology, University of Oxford, Oxford, England (F.V.G.); and Department of Radiology, The Churchill Hospital, Oxford University Hospitals NHS Trust, Headington, England (F.V.G.).

Background The full-scale airway network (FAN) flow model shows excellent agreement with limited functional imaging data but requires further validation prior to clinical use. Purpose To validate the ventilation distributions computed with the FAN flow model with xenon ventilation from xenon-enhanced dual-energy (DE) CT in participants with chronic obstructive pulmonary disease (COPD). Materials and Methods In this prospective study, the FAN model extracted structural data from xenon-enhanced DE CT images of men with COPD scanned between June 2012 and July 2013 to compute gas ventilation dynamics. The ventilation distributions on the middle cross-section plane, percentage lobar ventilation, and ventilation heterogeneity quantified by the coefficient of variation (CV) were compared between xenon-enhanced DE CT imaging and the FAN model. The relationship between the ventilation parameters with the densitometry and pulmonary function test results was demonstrated. The agreements and correlations between the parameters were measured using the concordance correlation coefficient and the Pearson correlation coefficient. Results Twenty-two men with COPD (mean age, 67 years ± 7 [standard deviation]) were evaluated. The percentage lobar ventilation computed with FAN showed a strong positive correlation with xenon-enhanced DE CT data ( = 0.7, < .001). Ninety-five percent of lobar ventilation CV differences lay within 95% confidence intervals. Correlations of the percentage lobar ventilation were negative for percentage emphysema (xenon-enhanced DE CT: = -0.38, < .001; FAN: = -0.23, = .02) but were positive for percentage normal tissue volume (xenon-enhanced DE CT: = 0.78, < .001; FAN: = 0.45, < .001). Lung CVs of FAN revealed negative correlations with the spirometry results (CV vs percentage predicted forced expiratory volume in 1 second: = -0.75, < .001; CV vs ratio of forced expiratory volume in 1 second to forced vital capacity: = -0.67, < .001). Conclusion The full-scale airway network modeled lobar ventilation in patients with chronic obstructive pulmonary disease correlated with the xenon-enhanced dual-energy CT imaging data. © RSNA, 2020 See also the editorial by Parraga and Eddy in this issue.
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http://dx.doi.org/10.1148/radiol.2020202485DOI Listing
January 2021

Content-Based Image Retrieval of Chest CT with Convolutional Neural Network for Diffuse Interstitial Lung Disease: Performance Assessment in Three Major Idiopathic Interstitial Pneumonias.

Korean J Radiol 2021 02 21;22(2):281-290. Epub 2020 Oct 21.

Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.

Objective: To assess the performance of content-based image retrieval (CBIR) of chest CT for diffuse interstitial lung disease (DILD).

Materials And Methods: The database was comprised by 246 pairs of chest CTs (initial and follow-up CTs within two years) from 246 patients with usual interstitial pneumonia (UIP, n = 100), nonspecific interstitial pneumonia (NSIP, n = 101), and cryptogenic organic pneumonia (COP, n = 45). Sixty cases (30-UIP, 20-NSIP, and 10-COP) were selected as the queries. The CBIR retrieved five similar CTs as a query from the database by comparing six image patterns (honeycombing, reticular opacity, emphysema, ground-glass opacity, consolidation and normal lung) of DILD, which were automatically quantified and classified by a convolutional neural network. We assessed the rates of retrieving the same pairs of query CTs, and the number of CTs with the same disease class as query CTs in top 1-5 retrievals. Chest radiologists evaluated the similarity between retrieved CTs and queries using a 5-scale grading system (5-almost identical; 4-same disease; 3-likelihood of same disease is half; 2-likely different; and 1-different disease).

Results: The rate of retrieving the same pairs of query CTs in top 1 retrieval was 61.7% (37/60) and in top 1-5 retrievals was 81.7% (49/60). The CBIR retrieved the same pairs of query CTs more in UIP compared to NSIP and COP ( = 0.008 and 0.002). On average, it retrieved 4.17 of five similar CTs from the same disease class. Radiologists rated 71.3% to 73.0% of the retrieved CTs with a similarity score of 4 or 5.

Conclusion: The proposed CBIR system showed good performance for retrieving chest CTs showing similar patterns for DILD.
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http://dx.doi.org/10.3348/kjr.2020.0603DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7817627PMC
February 2021

Visual and Quantitative Assessments of Regional Xenon-Ventilation Using Dual-Energy CT in Asthma-Chronic Obstructive Pulmonary Disease Overlap Syndrome: A Comparison with Chronic Obstructive Pulmonary Disease.

Korean J Radiol 2020 09;21(9):1104-1113

Department of Pulmonary and Critical Care Medicine, and Clinical Research Center for Chronic Obstructive Airway Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.

Objective: To assess the regional ventilation in patients with asthma-chronic obstructive pulmonary disease (COPD) overlap syndrome (ACOS) using xenon-ventilation dual-energy CT (DECT), and to compare it to that in patients with COPD.

Materials And Methods: Twenty-one patients with ACOS and 46 patients with COPD underwent xenon-ventilation DECT. The ventilation abnormalities were visually determined to be 1) peripheral wedge/diffuse defect, 2) diffuse heterogeneous defect, 3) lobar/segmental/subsegmental defect, and 4) no defect on xenon-ventilation maps. Emphysema index (EI), airway wall thickness (Pi10), and mean ventilation values in the whole lung, peripheral lung, and central lung areas were quantified and compared between the two groups using the Student's test.

Results: Most patients with ACOS showed the peripheral wedge/diffuse defect (n = 14, 66.7%), whereas patients with COPD commonly showed the diffuse heterogeneous defect and lobar/segmental/subsegmental defect (n = 21, 45.7% and n = 20, 43.5%, respectively). The prevalence of ventilation defect patterns showed significant intergroup differences ( < 0.001). The quantified ventilation values in the peripheral lung areas were significantly lower in patients with ACOS than in patients with COPD ( = 0.045). The quantified Pi10 was significantly higher in patients with ACOS than in patients with COPD ( = 0.041); however, EI was not significantly different between the two groups.

Conclusion: The ventilation abnormalities on the visual and quantitative assessments of xenon-ventilation DECT differed between patients with ACOS and patients with COPD. Xenon-ventilation DECT may demonstrate the different physiologic changes of pulmonary ventilation in patients with ACOS and COPD.
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http://dx.doi.org/10.3348/kjr.2019.0936DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7371623PMC
September 2020

Quantitative Vertebral Bone Density Seen on Chest CT in Chronic Obstructive Pulmonary Disease Patients: Association with Mortality in the Korean Obstructive Lung Disease Cohort.

Korean J Radiol 2020 07;21(7):880-890

Department of Pulmonary and Critical Care Medicine, and Clinical Research Center for Chronic Obstructive Airway Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.

Objective: Patients with chronic obstructive pulmonary disease (COPD) are known to be at risk of osteoporosis. The purpose of this study was to evaluate the association between thoracic vertebral bone density measured on chest CT (D) and clinical variables, including survival, in patients with COPD.

Materials And Methods: A total of 322 patients with COPD were selected from the Korean Obstructive Lung Disease (KOLD) cohort. D was measured by averaging the CT values of three consecutive vertebral bodies at the level of the left main coronary artery with a round region of interest as large as possible within the anterior column of each vertebral body using an in-house software. Associations between D and clinical variables, including survival, pulmonary function test (PFT) results, and CT densitometry, were evaluated.

Results: The median follow-up time was 7.3 years (range: 0.1-12.4 years). Fifty-six patients (17.4%) died. D differed significantly between the different Global Initiative for Chronic Obstructive Lung Disease stages. D correlated positively with body mass index (BMI), some PFT results, and the six-minute walk distance, and correlated negatively with the emphysema index (EI) (all < 0.05). In the univariate Cox analysis, older age (hazard ratio [HR], 3.617; 95% confidence interval [CI], 2.119-6.173, < 0.001), lower BMI (HR, 3.589; 95% CI, 2.122-6.071, < 0.001), lower forced expiratory volume in one second (FEV₁) (HR, 2.975; 95% CI, 1.682-5.262, < 0.001), lower diffusing capacity of the lung for carbon monoxide corrected with hemoglobin (DL) (HR, 4.595; 95% CI, 2.665-7.924, < 0.001), higher EI (HR, 3.722; 95% CI, 2.192-6.319, < 0.001), presence of vertebral fractures (HR, 2.062; 95% CI, 1.154-3.683, = 0.015), and lower D (HR, 2.773; 95% CI, 1.620-4.746, < 0.001) were significantly associated with all-cause mortality and lung-related mortality. In the multivariate Cox analysis, lower D (HR, 1.957; 95% CI, 1.075-3.563, = 0.028) along with older age, lower BMI, lower FEV₁, and lower DL were independent predictors of all-cause mortality.

Conclusion: The thoracic vertebral bone density measured on chest CT demonstrated significant associations with the patients' mortality and clinical variables of disease severity in the COPD patients included in KOLD cohort.
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http://dx.doi.org/10.3348/kjr.2019.0551DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7289694PMC
July 2020

Differentiation of predominant subtypes of lung adenocarcinoma using a quantitative radiomics approach on CT.

Eur Radiol 2020 Sep 16;30(9):4883-4892. Epub 2020 Apr 16.

Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, 88 Olympic-ro 43 Gil, Songpa-gu, Seoul, 138-736, South Korea.

Objectives: To develop a model for differentiating the predominant subtype-based prognostic groups of lung adenocarcinoma using CT radiomic features, and to validate its performance in comparison with radiologists' assessments.

Methods: A total of 993 patients presenting with invasive lung adenocarcinoma between March 2010 and June 2016 were identified. Predominant histologic subtypes were categorized into three groups according to their prognosis (group 0: lepidic; group 1: acinar/papillary; group 2: solid/micropapillary). Seven hundred eighteen radiomic features were extracted from segmented lung cancers on contrast-enhanced CT. A model-development set was formed from the images of 893 patients, while 100 image sets were reserved for testing. A least absolute shrinkage and selection operator method was used for feature selection. Performance of the radiomic model was evaluated using receiver operating characteristic curve analysis, and accuracy on the test set was compared with that of three radiologists with varying experiences (6, 7, and 19 years in chest CT).

Results: Our model differentiated the three groups with areas under the curve (AUCs) of 0.892 and 0.895 on the development and test sets, respectively. In pairwise discrimination, the AUC was highest for group 0 vs. 2 (0.984). The accuracy of the model on the test set was higher than the averaged accuracy of the three radiologists without statistical significance (73.0% vs. 61.7%, p = 0.059). For group 2, the model achieved higher PPV than the observers (85.7% vs. 35.0-48.4%).

Conclusions: Predominant subtype-based prognostic groups of lung adenocarcinoma were classified by a CT-based radiomic model with comparable performance to radiologists.

Key Points: • A CT-based radiomic model differentiated three prognosis-based subtype groups of lung adenocarcinoma with areas under the curve (AUCs) of 0.892 and 0.895 on development and test sets, respectively. • The CT-based radiomic model showed near perfect discrimination between group 0 and group 2 (AUCs, 0.984-1.000). • The accuracy of the CT-based radiomic model was comparable to the averaged accuracy of the three radiologists with 6, 7, and 19 years of clinical experience in chest CT (73.0% vs. 61.7%, p = 0.059), achieving a higher positive predictive value for group 2 than the observers (85.7% vs. 35.0-48.4%).
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http://dx.doi.org/10.1007/s00330-020-06805-wDOI Listing
September 2020

Short-term Reproducibility of Pulmonary Nodule and Mass Detection in Chest Radiographs: Comparison among Radiologists and Four Different Computer-Aided Detections with Convolutional Neural Net.

Sci Rep 2019 12 10;9(1):18738. Epub 2019 Dec 10.

Department of Convergence Medicine, University of Ulsan College of Medicine, Asan Medical Center, Seoul, South Korea.

To investigate the reproducibility of computer-aided detection (CAD) for detection of pulmonary nodules and masses for consecutive chest radiographies (CXRs) of the same patient within a short-term period. A total of 944 CXRs (Chest PA) with nodules and masses, recorded between January 2010 and November 2016 at the Asan Medical Center, were obtained. In all, 1092 regions of interest for the nodules and mass were delineated using an in-house software. All CXRs were randomly split into 6:2:2 sets for training, development, and validation. Furthermore, paired follow-up CXRs (n = 121) acquired within one week in the validation set, in which expert thoracic radiologists confirmed no changes, were used to evaluate the reproducibility of CAD by two radiologists (R1 and R2). The reproducibility comparison of four different convolutional neural net algorithms and two chest radiologists (with 13- and 14-years' experience) was conducted. Model performances were evaluated by figure-of-merit (FOM) analysis of the jackknife free-response receiver operating curve and reproducibility rates were evaluated in terms of percent positive agreement (PPA) and Chamberlain's percent positive agreement (CPPA). Reproducibility analysis of the four CADs and R1 and R2 showed variations in the PPA and CPPA. Model performance of YOLO (You Only Look Once) v2 based eDenseYOLO showed a higher FOM (0.89; 0.85-0.93) than RetinaNet (0.89; 0.85-0.93) and atrous spatial pyramid pooling U-Net (0.85; 0.80-0.89). eDenseYOLO showed higher PPAs (97.87%) and CPPAs (95.80%) than Mask R-CNN, RetinaNet, ASSP U-Net, R1, and R2 (PPA: 96.52%, 94.23%, 95.04%, 96.55%, and 94.98%; CPPA: 93.18%, 89.09%, 90.57%, 93.33%, and 90.43%). There were moderate variations in the reproducibility of CAD with different algorithms, which likely indicates that measurement of reproducibility is necessary for evaluating CAD performance in actual clinical environments.
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http://dx.doi.org/10.1038/s41598-019-55373-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6904482PMC
December 2019

Anaplastic lymphoma kinase inhibitor related pneumonitis in patients with non-small cell lung cancer: Clinical and radiologic characteristics and risk factors.

Medicine (Baltimore) 2019 Nov;98(48):e18131

Department of Pulmonary and Critical Care Medicine, and Division of Oncology, Asan Medical Center, University of Ulsan College of Medicine, Songpa-Gu, Seoul, South Korea.

Anaplastic lymphoma kinase (ALK) inhibitor-related pneumonitis (ALK-IIP) is relatively rare but sometimes fatal, so the timely diagnosis of ALK-IIP is important for enabling prompt management. However, the detailed radiologic characteristics and clinical course of ALK-IIP are still unclear. This study was performed to investigate the clinical and radiologic characteristics and risk factors of ALK-IIP in patients with non-small cell lung cancer (NSCLC).A total of 250 NSCLC patients who had been treated with ALK inhibitors were retrospectively enrolled. Chest computed tomography (CT) was classified into 4 CT patterns using the 2013 guideline for idiopathic interstitial pneumonia: cryptogenic organizing pneumonia (COP), hypersensitivity pneumonitis (HP), acute interstitial pneumonia (AIP), and nonspecific interstitial pneumonia. Clinical characteristics including toxicity grading and treatment course were analyzed in regarding to CT patterns. Clinical characteristics were compared between patients with ALK-IIP and without ALK-IIP.ALK-IIP was identified in 11 patients (4.4%). The most common CT pattern was the COP pattern (n = 7, 63.6%) and followed by HP and AIP patterns (both, n = 2, 18.2%). ALK-IIP showed pneumonitis toxicity grade ranged from 1 to 4, and AIP pattern had the highest toxicity grade, followed by HP and COP patterns (median grade: 3.5, 2.5, 1). All of the patients with the COP pattern were successfully treated, while half of patients with the AIP pattern died during treatment. The smoking history and extrathoracic metastasis were more frequent in patients with ALK-IIP (P < .005). The smoking history was associated with a higher incidence of ALK-IIP (odds ratio: 3.586, 95% confidence interval: 1.058-13.432, P = .049).ALK-IIP showed a spectrum of chest CT patterns, which reflected the toxicity grades. The COP pattern was the most common CT pattern of ALK-IIP, and patients with ALK-IIP of the COP pattern were successfully treated. ALK inhibitors should be used with caution in NSCLC patients with smoking history.
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http://dx.doi.org/10.1097/MD.0000000000018131DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6890272PMC
November 2019

Comparison of chest radiographic findings between severe fever with thrombocytopenia syndrome and scrub typhus: Single center observational cross-sectional study in South Korea.

Medicine (Baltimore) 2019 Nov;98(46):e17701

Department of Infectious Diseases.

Severe fever with thrombocytopenia syndrome (SFTS) is an emerging infectious disease caused by SFTS virus (SFTSV) which involves multiple organ systems, including lungs. However, there is limited data on lung involvement of SFTS. Therefore, the present study investigated the chest radiographic findings of SFTS, including computed tomography (CT), and compared these with those of scrub typhus, which is the most common tick-borne illness in South Korea and share risk factors and occur in similar settings.Medical records of patients with confirmed SFTS and scrub typhus in a tertiary hospital in Seoul (South Korea), between January 2014 and June 2018, were reviewed. Initial chest radiography and CT were reviewed by 2 experienced radiologists.A total of 39 patients with SFTS and 101 patients with scrub typhus were analyzed. All patients except 3 patients with scrub typhus in both groups received chest radiography. Cardiomegaly (90%) and patchy consolidation with ground glass opacity (GGO) pattern (31%) were more common in SFTS group than scrub typhus group (20%, P < .001 and 2%, P < .001, respectively). About half of each group received chest CT. Consolidation (29%) and pericardial effusion (24%) were more common in SFTS group than scrub typhus group (6%, P = .02 and 4%, P = .008, respectively). Interstitial thickening in chest radiography (58%) and chest CT (65%) was more frequent in scrub typhus group than SFTS group (18%, P < .001 and 19%, P < .001, respectively).Cardiomegaly with/without pericardial effusion and patchy consolidation with GGO pattern were more frequent in SFTS group, whereas interstitial thickening was more frequent in scrub typhus group. These findings will assist the early differentiation of SFTS from scrub typhus.
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http://dx.doi.org/10.1097/MD.0000000000017701DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6867728PMC
November 2019

Assessment Of Changes In Regional Xenon-Ventilation, Perfusion, And Ventilation-Perfusion Mismatch Using Dual-Energy Computed Tomography After Pharmacological Treatment In Patients With Chronic Obstructive Pulmonary Disease: Visual And Quantitative Analysis.

Int J Chron Obstruct Pulmon Dis 2019 25;14:2195-2203. Epub 2019 Sep 25.

Department of Pulmonary and Critical Care Medicine, Clinical Research Center for Chronic Obstructive Airway Diseases, Asan Medical Center, University of Ulsan College of Medicine, Songpa-Gu, Seoul 138-736, South Korea.

Purpose: To assess changes in regional ventilation (V), perfusion (Q), and V-Q mismatch in patients with chronic obstructive pulmonary disease (COPD) after pharmacologic treatment using combined xenon-enhanced V and iodine-enhanced Q dual-energy CT (DECT).

Patients And Methods: Combined V and Q DECT were performed at baseline and after three-month pharmacologic treatment in 52 COPD patients. Anatomically co-registered virtual non-contrast images, V, Q, and V/Q maps were obtained. V/Q pattern was visually determined to be matched, mismatched, or reversed-mismatched and compared with the regional parenchymal disease patterns of each segment. DECT parameters for V, Q, and V-Q imbalance were quantified.

Results: The parenchymal patterns on CT were not changed at follow-up. The segments with matched V/Q pattern were increased (80.2% to 83.6%) as the segments with reversed-mismatched V/Q pattern were decreased with improving ventilation (17.6% to 13.8%) after treatment. Changes of V/Q patterns were mostly observed in segments with bronchial wall thickening. Compared with patients without bronchial wall thickening, the quantified DECT parameters of V-Q imbalance were significantly improved in patients with bronchial wall thickening ( < 0.05). Changes in forced expiratory volume in one second after treatment were correlated with changes in the quantified DECT parameters ( = 0.327-0.342 or = -0.406 and -0.303; < 0.05).

Conclusion: DECT analysis showed that the V-Q imbalance was improved after the pharmacological treatment in COPD patients, although the parenchymal disease patterns remained unchanged. This improvement of V-Q imbalance may occur mostly in the areas with bronchial wall thickening.
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http://dx.doi.org/10.2147/COPD.S210555DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6768130PMC
April 2020

Invasive Pulmonary Aspergillosis in Patients With Severe Fever With Thrombocytopenia Syndrome.

Clin Infect Dis 2020 03;70(7):1491-1494

Department of Infectious Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.

Sixteen of 45 patients with severe fever with thrombocytopenia (36%) were admitted to an intensive care unit; 9 (56%) developed invasive pulmonary aspergillosis (IPA) within a median of 8 days (range, 2-11). Mortality was higher in the IPA vs non-IPA patients and in those without vs with antifungal therapy.
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http://dx.doi.org/10.1093/cid/ciz673DOI Listing
March 2020

High-pitch, 120 kVp/30 mAs, low-dose dual-source chest CT with iterative reconstruction: Prospective evaluation of radiation dose reduction and image quality compared with those of standard-pitch low-dose chest CT in healthy adult volunteers.

PLoS One 2019 24;14(1):e0211097. Epub 2019 Jan 24.

Department of Radiology, Hallym University Medical Center, Hallym University Sacred Heart Hospital, Anyang-si, Gyeonggi-do, Republic of Korea.

Purpose: Objective of this study was to evaluate the effectiveness of the iterative reconstruction of high-pitch dual-source chest CT (IR-HP-CT) scanned with low radiation exposure compared with low dose chest CT (LDCT).

Materials And Methods: This study was approved by the institutional review board. Thirty healthy adult volunteers (mean age 44 years) were enrolled in this study. All volunteers underwent both IR-HP-CT and LDCT. IR-HP-CT was scanned with 120 kVp tube voltage, 30 mAs tube current and pitch 3.2 and reconstructed with sinogram affirmed iterative reconstruction. LDCT was scanned with 120 kVp tube voltage, 40 mAs tube current and pitch 0.8 and reconstructed with B50 filtered back projection. Image noise, and signal to noise ratio (SNR) of the infraspinatus muscle, subcutaneous fat and lung parenchyma were calculated. Cardiac motion artifact, overall image quality and artifacts was rated by two blinded readers using 4-point scale. The dose-length product (DLP) (mGy∙cm) were obtained from each CT dosimetry table. Scan length was calculated from the DLP results. The DLP parameter was a metric of radiation output, not of patient dose. Size-specific dose estimation (SSDE, mGy) was calculated using the sum of the anteroposterior and lateral dimensions and effective radiation dose (ED, mSv) were calculated using CT dosimetry index.

Results: Approximately, mean 40% of SSDE (2.1 ± 0.2 mGy vs. 3.5 ± 0.3 mGy) and 34% of ED (1.0 ± 0.1 mSv vs. 1.5 ± 0.1 mSv) was reduced in IR-HP-CT compared to LDCT (P < 0.0001). Image noise was reduced in the IR-HP-CT (16.8 ± 2.8 vs. 19.8 ± 3.4, P = 0.0001). SNR of lung and aorta of IR-HP-CT showed better results compared with that of LDCT (22.2 ± 5.9 vs. 33.0 ± 7.8, 1.9 ± 0.4 vs 1.1 ± 0.3, P < 0.0001). The score of cardiac pulsation artifacts were significantly reduced on IR-HP-CT (3.8 ± 0.4, 95% confidence interval, 3.7‒4.0) compared with LDCT (1.6 ± 0.6, 95% confidence interval, 1.3‒1.8) (P < 0.0001). SNR of muscle and fat, beam hardening artifact and overall subjective image quality of the mediastinum, lung and chest wall were comparable on both scans (P ≥ 0.05).

Conclusion: IR-HP-CT with 120 kVp and 30 mAs tube setting in addition to an iterative reconstruction reduced cardiac motion artifact and radiation exposure while representing similar image quality compared with LDCT.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0211097PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6345490PMC
October 2019

Ischemic burden assessment of myocardial perfusion CT, compared with SPECT using semi-quantitative and quantitative approaches.

Int J Cardiol 2019 Mar 17;278:287-294. Epub 2018 Dec 17.

Division of Cardiology, Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea. Electronic address:

Background: We aimed to compare the myocardial ischemic burden assessed using semi-quantitative and quantitative analysis of computed tomography-myocardial perfusion imaging (CT-MPI) with that of single-photon emission computed tomography (SPECT).

Methods: From 2011 to 2013, 97 patients who underwent CT-MPI and SPECT were evaluated. The extent and severity of perfusion defects were assessed on a 5-point scale using a standard 16-segment model, and were expressed as summed stress score (SSS) and summed difference score (SDS). Receiver operating characteristic (ROC) curves for quantitative parameters were generated for the diagnosis of abnormal perfusion defect (SSS ≥ 4) and presence of ischemia (SDS ≥ 2) on SPECT.

Results: On CT-MPI, 298 (19.2%) of the 1552 segments showed perfusion abnormalities during stress, whereas perfusion abnormalities were shown in 179 (11.5%) segments on SPECT-MPI. On a per-person basis, there was good agreement, with intraclass correlation coefficients of 0.78 for SSS and 0.72 for SDS. A significant reduction of attenuation in stress and myocardial perfusion reserve index, along with an increase in % defect volume of CT-MPI, were demonstrated as the degree of perfusion defect or ischemia on SPECT increased. On the ROC curves, % defect volume on CT-MPI demonstrated the highest area under the curve: 0.91 for abnormal perfusion defect and 0.89 (all p < 0.001) for the presence of ischemia on SPECT.

Conclusions: Semi-quantitative analysis of CT-MPI showed good accordance with SPECT. A quantitative approach for CT-MPI, especially % defect volume, may provide additional value in the identification of myocardial perfusion abnormalities.

Clinical Trial Registration: https://clinicaltrials.gov/ct2/show/NCT01696006.
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http://dx.doi.org/10.1016/j.ijcard.2018.12.046DOI Listing
March 2019

Geographic and demographic variabilities of quantitative parameters in stress myocardial computed tomography perfusion.

Korean J Intern Med 2017 Sep 28;32(5):847-854. Epub 2017 Jul 28.

Division of Cardiology, Department of Internal Medicine, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.

Background/aims: To evaluate the geographic and demographic variabilities of the quantitative parameters of computed tomography perfusion (CTP) of the left ventricular (LV) myocardium in patients with normal coronary artery on computed tomography angiography (CTA).

Methods: From a multicenter CTP registry of stress and static computed tomography, we retrospectively recruited 113 patients (mean age, 60 years; 57 men) without perfusion defect on visual assessment and minimal (< 20% of diameter stenosis) or no coronary artery disease on CTA. Using semiautomatic analysis software, quantitative parameters of the LV myocardium, including the myocardial attenuation in stress and rest phases, transmural perfusion ratio (TPR), and myocardial perfusion reserve index (MPRI), were evaluated in 16 myocardial segments.

Results: In the lateral wall of the LV myocardium, all quantitative parameters except for MPRI were significantly higher compared with those in the other walls. The MPRI showed consistent values in all myocardial walls (anterior to lateral wall: range, 25% to 27%; = 0.401). At the basal level of the myocardium, all quantitative parameters were significantly lower than those at the mid- and apical levels. Compared with men, women had significantly higher values of myocardial attenuation and TPR. Age, body mass index, and Framingham risk score were significantly associated with the difference in myocardial attenuation.

Conclusions: Geographic and demographic variabilities of quantitative parameters in stress myocardial CTP exist in healthy subjects without significant coronary artery disease. This information may be helpful when assessing myocardial perfusion defects in CTP.
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http://dx.doi.org/10.3904/kjim.2016.012DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5583451PMC
September 2017

The 100 Top-Cited Articles in Pulmonary Imaging: A Bibliometric Analysis.

J Thorac Imaging 2017 May;32(3):198-202

*Department of Radiology, Kangdong Sacred Heart Hospital, Hallym University College of Medicine, Seoul †Department of Radiology, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, Anyang-si, South Korea.

Purpose: The purpose of this study was to identify and characterize the 100 top-cited articles in pulmonary imaging.

Materials And Methods: From the database of Journal Citation Reports, 274 journals whose scope included pulmonary imaging were selected. The Web of Science search tools were then used to identify the 100 top-cited articles in the subject of pulmonary imaging published in these journals. The parameters used to analyze the characteristics of the 100 top-cited articles were journal (including subject category and impact factor), publication year, number of citations and annual citations, department and institution of authors, country of origin, article type, imaging technique, and topic.

Results: The 100 top-cited articles in pulmonary imaging were published between 1953 and 2012, with 43 published between 2000 and 2009. Citations ranged from 199 to 1447, and annual citations ranged from 5.1 to 314. The majority of articles were published in radiology or imaging journals (n=64), originated in the United States (n=49), were original articles (n=87), used computed tomography (n=66), and were based on the topic of pulmonary thromboembolism (n=18). Department of Radiology, Mayo Clinic (n=7), and Department of Radiology, University of British Columbia and Vancouver General Hospital (n=7), were the leading institutions, and Müller NL (n=11) was the most prolific author.

Conclusions: Our study lists the 100 top-cited articles in pulmonary imaging, provides an insight into historical developments, and allows for recognition of advances in this field.
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http://dx.doi.org/10.1097/RTI.0000000000000251DOI Listing
May 2017

Assessment of regional emphysema, air-trapping and Xenon-ventilation using dual-energy computed tomography in chronic obstructive pulmonary disease patients.

Eur Radiol 2017 Jul 23;27(7):2818-2827. Epub 2016 Nov 23.

Department of Radiology, Research Istitute of Radiological Science, Yonsei University College of Medicine, Gangnam Severance Hospital, 221, Eonju-ro, Gangnam-gu, Seoul, 06273, Republic of Korea.

Objectives: To compare the parenchymal attenuation change between inspiration/expiration CTs with dynamic ventilation change between xenon wash-in (WI) inspiration and wash-out (WO) expiration CTs.

Methods: 52 prospectively enrolled COPD patients underwent xenon ventilation dual-energy CT during WI and WO periods and pulmonary function tests (PFTs). The parenchymal attenuation parameters (emphysema index (EI), gas-trapping index (GTI) and air-trapping index (ATI)) and xenon ventilation parameters (xenon in WI (Xe-WI), xenon in WO (Xe-WO) and xenon dynamic (Xe-Dyna)) of whole lung and three divided areas (emphysema, hyperinflation and normal) were calculated on virtual non-contrast images and ventilation images. Pearson correlation, linear regression analysis and one-way ANOVA were performed.

Results: EI, GTI and ATI showed a significant correlation with Xe-WI, Xe-WO and Xe-Dyna (EI R = -.744, -.562, -.737; GTI R = -.621, -.442, -.629; ATI R = -.600, -.421, -.610, respectively, p < 0.01). All CT parameters showed significant correlation with PFTs except forced vital capacity (FVC). There was a significant difference in GTI, ATI and Xe-Dyna in each lung area (p < 0.01).

Conclusions: The parenchymal attenuation change between inspiration/expiration CTs and xenon dynamic change between xenon WI- and WO-CTs correlate significantly. There are alterations in the dynamics of xenon ventilation between areas of emphysema.

Key Points: • The xenon ventilation change correlates with the parenchymal attenuation change. • The xenon ventilation change shows the difference between three lung areas. • The combination of attenuation and xenon can predict more accurate PFTs.
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http://dx.doi.org/10.1007/s00330-016-4657-zDOI Listing
July 2017

The role of dual-energy computed tomography in the assessment of pulmonary function.

Eur J Radiol 2017 Jan 8;86:320-334. Epub 2016 Nov 8.

Department of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, 388-1, Pungnap 2-dong, Songpa-ku, Seoul, 05505, Republic of Korea. Electronic address:

The assessment of pulmonary function, including ventilation and perfusion status, is important in addition to the evaluation of structural changes of the lung parenchyma in various pulmonary diseases. The dual-energy computed tomography (DECT) technique can provide the pulmonary functional information and high resolution anatomic information simultaneously. The application of DECT for the evaluation of pulmonary function has been investigated in various pulmonary diseases, such as pulmonary embolism, asthma and chronic obstructive lung disease and so on. In this review article, we will present principles and technical aspects of DECT, along with clinical applications for the assessment pulmonary function in various lung diseases.
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http://dx.doi.org/10.1016/j.ejrad.2016.11.010DOI Listing
January 2017

Assessment of Regional Xenon Ventilation, Perfusion, and Ventilation-Perfusion Mismatch Using Dual-Energy Computed Tomography in Chronic Obstructive Pulmonary Disease Patients.

Invest Radiol 2016 May;51(5):306-15

From the *Department of Radiology, Hallym University College of Medicine, Hallym University Sacred Heart Hospital, Anyang, Gyeonggi; †Department of Radiology, ‡Research Institute of Radiology, §Department of Pulmonary and Critical Care Medicine, and ║Clinical Research Center for Chronic Obstructive Airway Diseases, Asan Medical Center, University of Ulsan College of Medicine, Seoul, Republic of Korea.

Objectives: The aim of this study was to assess the feasibility of combined xenon-enhanced ventilation (V) and iodine-enhanced perfusion (Q) dual-energy computed tomography (DECT) to evaluate regional V and Q status in patients with chronic obstructive pulmonary disease (COPD).

Materials And Methods: Combined V and Q DECT imaging was performed in 52 prospectively enrolled male COPD patients. Virtual noncontrast images, V maps, and Q maps were anatomically coregistered with deformable registration and evaluated using in-house software. After normalization of the V and Q values of each pixel, normalized V and Q, V/Qratio, and VQmin (ie, the smaller of the V and Q in each pixel) maps were generated. For visual analysis, the V/Qratio pattern was determined to be matched, mismatched, or reversed mismatched and compared with the regional disease patterns--emphysema with/without bronchial wall thickening, bronchial wall thickening, or normal parenchyma--in each segment. The mean V, Q, V/Qratio, and VQmin values and the standard deviation of the V/Qratio (V/QSD) of each patient were quantified and compared with pulmonary function test (PFT) parameters using the Pearson correlation test.

Results: Segments with normal parenchyma showed a matched V/Qratio pattern, whereas segments with bronchial wall thickening commonly showed a reversed mismatched V/Qratio pattern. In the emphysema areas, the matched, mismatched, and reversed mismatched patterns were mixed without a dominant pattern. In quantitative analysis, the mean V, Q, VQmin, and V/Qratio values were significantly and positively correlated with PFT parameters (r = 0.290-0.819; P < 0.05). The V/QSD was significantly and negatively correlated with PFT parameters (r = -0.439 to -0.736; P < 0.001). VQmin values showed the best correlation with PFT parameters (r = 0.483-0.819; P < 0.001).

Conclusions: Visual and quantitative assessment of the regional V, Q, V/Qratio, and VQmin is feasible with combined V and Q DECT imaging and significantly correlate with PFT results in COPD patients. Assessing disease patterns using conventional computed tomography images may not provide correct evaluation of regional V and Q in COPD patients with emphysema.
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http://dx.doi.org/10.1097/RLI.0000000000000239DOI Listing
May 2016

Intramural esophageal dissection diagnosed on transabdominal ultrasonography.

Jpn J Radiol 2015 Dec 22;33(12):764-8. Epub 2015 Oct 22.

Department of Radiology, Hallym University Medical Center, Hallym University Sacred Heart Hospital, 896, Pyeongchon-dong, Dongan-gu, Anyang-si, Gyeonggi-do, 431-070, Republic of Korea.

Intramural esophageal dissection (IED) is an uncommon yet important clinical entity characterized by a rupture or fissure in the esophageal submucosal layer. IED could occur spontaneously or secondary to direct extrinsic injury to the esophageal mucosa. Traditionally, IED has been diagnosed on the swallowing study using water-soluble contrast agents or barium. For alternative diagnostic modalities, upper gastrointestinal endoscopy and chest computed tomography have been frequently performed. However, to the best of our knowledge, the transabdominal ultrasonography (USG) appearance of IED has not been reported in the literature yet. We report an interesting case of IED, which was initially diagnosed on the transabdominal USG.
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http://dx.doi.org/10.1007/s11604-015-0488-0DOI Listing
December 2015

CT Characteristic of Early Local Recurrence After Resection of the Squamous Cell Carcinoma: Comparison With CT Characteristics of Stump Deformity or Granulation Tissue at Stump Site.

Medicine (Baltimore) 2015 Oct;94(41):e1691

From the Department of Radiology, Hallym University College of Medicine, Hallym University Sacred Heart Hospital, Dongan-gu, Anyang-si, Gyeonggi-do (HJH); Departments of Radiology and Research Institute of Radiology, Asan Medical Center, University of Ulsan College of Medicine, Songpa-Gu, Seoul (MYK); Department of Healthcare Management, Cheongju University, Cheongwon-fu, Cheongju-si, Chungcheongbuk-do (S-SK); and Department of Pulmonary and Critical Care Medicine, and Division of Oncology, University of Ulsan College of Medicine, Asan Medical Center, Songpa-Gu, Seoul, Korea (C-MC).

The aim of this study is to compare the thin section computed tomography (CT) characteristics of the early local tumor recurrence with those of the stump deformity or granulation tissue after the resection of squamous cell carcinoma (SCC).Twenty-nine consecutive patients with local recurrence after definitive SCC operation from April 2006 to September 2012 were included in our study. Pre- and postoperative CT findings from these patients were retrospectively reviewed and compared with those in the age- and sex-matched 29 patients with the stump deformity or granulation tissue at stump site after definitive SCC operation, by 2 radiologists. We evaluated the initial tumor stage, tumor size, and tumor location in relation with the bronchus on preoperative CT scan. On postoperative CT scan, we evaluated the size, CT characteristics, and involvement pattern of the suspected soft tissue around the stump site, and the distance between surgical staples and soft tissue at the stump site.Tumor stage, tumor size, and tumor location in relation with the bronchus on preoperative CT scan were not significantly different between 2 groups, while lymph node stage was more advanced in the local recurrence group. On postoperative CT scan, the size of suspected soft tissue at stump site is significantly larger, and the distance between stump staples and suspected soft tissue was significantly longer in the local recurrence group than control group (median; 19 mm and 3 mm; 18 mm and 0 mm, respectively, P < 0.001). The univariate analysis showed that the size of soft tissue and the distance between soft tissue and stump site on postoperative CT scan were associated with the predictive factors of local recurrence (P < 0.001). On the receiver-operating characteristic analysis, the optimal cutoffs of the size of soft tissue and the distance between soft tissue and stump staples for determining local tumor recurrence were 6 and 5 mm, respectively.The proper knowledge CT characteristics of local tumor recurrence including the soft tissue size (cut-off, 6 mm) and the distance (cut-off, 5 mm) between soft tissue and stump site will help us achieve the early diagnosis and higher diagnostic rate of locally recurred SCC.
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http://dx.doi.org/10.1097/MD.0000000000001691DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4616788PMC
October 2015

Newly detected pulmonary nontuberculous mycobacterial infection and peripheral lung cancers in patients during follow-up of idiopathic interstitial pneumonia: comparison of CT findings.

Medicine (Baltimore) 2015 Apr;94(13):e691

From the Department of Radiology and Research Institute of Radiology (SYO, MYK); Department of Pulmonary and Critical Care Medicine (TSS, C-MC, DSK); Department of Oncology (C-MC), University of Ulsan College of Medicine, Asan Medical Center, Seoul, South Korea; and Hallym University College of Medicine (HJH), Hallym University, Sacred Heart Hospital, Anyang, and Department of Healthcare Management (S-SK), Cheongju University, Cheongju, South Korea.

This article describes the difference between the computed tomography (CT) findings in patients with newly detected pulmonary nontuberculous mycobacterial infection (NTM-IIP) and Cancer-IIP. We retrospectively evaluated 35 NTM-IIP and 78 Cancer-IIP patients in reference to their null idiopathic interstitial pneumonia CT (n = 113), using >10 years of data. Two independent radiologists analyzed the CT characteristics and the axial location of the main opacity. The interobserver agreement was good (κ > 0.771). The NTM-IIP patients were older (P = 0.034). The median size of the main opacity in the NTM-IIP (27 mm; 11-73) was larger (19 mm; 5-60; P = 0.002). Consolidation (n = 30; 85.7%; odds ratio [OR], 45) and cavities (n = 14; 40%, OR, 25) were more common in NTM-IIP (all P < 0.001). The midst of the fibrotic cysts including honeycomb cysts (n = 16; 45.7%, OR, 4.95) was more common in NTM-IIP (P = 0.006). NTM-IIP appeared larger, with more frequent consolidation and cavities, and was more likely to have been located in the midst of the fibrotic cysts including honeycomb cysts at the CT, which showed that it was older than Cancer-IIP.
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http://dx.doi.org/10.1097/MD.0000000000000691DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4554021PMC
April 2015

Comparison of a New Integral-Based Half-Band Method for CT Measurement of Peripheral Airways in COPD With a Conventional Full-Width Half-Maximum Method Using Both Phantom and Clinical CT Images.

J Comput Assist Tomogr 2015 May-Jun;39(3):428-36

From the Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.

Objectives: To compare a new integral-based half-band method (IBHB) and a conventional full-width half-maximum (FWHM) method in measuring peripheral airway dimensions at airway phantoms and thin-section computed tomography of chronic obstructive pulmonary disease (COPD).

Methods: The IBHB was validated and compared using airway phantoms and 50 patients with COPD. Airway parameters (wall area percentage [WA%], mean lumen radius, and mean wall thickness) were measured at fourth to sixth generations of the right apical bronchus. Matched results from 2 methods were compared and correlated with forced expiratory volume (FEV) in 1 second (FEV1), FEV1 / forced vital capacity (FVC), and global initiative for chronic obstructive lung disease (GOLD) stage. Linear regression analysis was performed using airway dimensions and emphysema index.

Results: The IBHB generated more accurate measurements at phantom study. Measured airway parameters by both methods at thin-section computed tomography study were significantly different (all P < 0.05, paired t test). The IBHB method-measured WA% and wall thickness were significantly smaller. Mean WA% with IBHB also showed better correlation than that with FWHM (FEV1, r = -0.52 vs -0.28; FEV1 / FVC, r = -0.41 vs r = -0.20; GOLD, 0.52 vs 0.33, respectively). Linear regression analysis revealed fifth-generation WA% measured by IBHB was an independent variable, and addition to emphysema index increased predictability (FEV1, r = 0.63; FEV1 / FVC, r = 0.61; GOLD, r = 0.70).

Conclusions: The new IBHB measured peripheral airway dimensions differently than FWHM and showed better correlations with functional parameters in COPD.
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http://dx.doi.org/10.1097/RCT.0000000000000218DOI Listing
July 2015

Advanced adenocarcinoma of the lung: comparison of CT characteristics of patients with anaplastic lymphoma kinase gene rearrangement and those with epidermal growth factor receptor mutation.

Radiology 2015 Apr 7;275(1):272-9. Epub 2015 Jan 7.

From the Departments of Pulmonary and Critical Care Medicine (C.M.C., W.S.K.), Oncology (C.M.C.), Radiology and Research Institute of Radiology (M.Y.K.), and Clinical Epidemiology and Biostatistics (J.B.L.), University of Ulsan College of Medicine, Asan Medical Center, 86 Asanbyeongwon-Gil, Songpa-Gu, Seoul 138-736, Korea; and Department of Radiology, Hallym University College of Medicine, Hallym University Sacred Heart Hospital, Seoul, Korea (H.J.H.).

Purpose: To study the differences in computed tomographic (CT) characteristics between patients with advanced lung adenocarcinoma who have anaplastic lymphoma kinase (ALK) gene rearrangement and those who have epidermal growth factor receptor (EGFR) mutations.

Materials And Methods: This retrospective study was approved by the institutional review board. Informed consent was waived. Patients with stage IV adenocarcinoma (n = 198) were enrolled from November 2004 to December 2013, including 68 patients with ALK rearrangement and 130 with EGFR mutation. Two independent radiologists evaluated the main tumor in each patient and determined its size, type, margins, lymph node metastasis, and intrathoracic metastasis (lung, pleural or pericardial, or bone). A multiple logistic regression model was applied to discriminate clinical and CT characteristics between the types of mutation.

Results: The κ index for assessment of tumor and node stage between radiologists was 0.8530 to 0.9388. Most of the main tumors in patients with both types of mutation appeared as solid masses. In univariate analysis, patients with an ALK rearrangement were younger (P < .001) and were more likely to be men (P = .001), to have never smoked (P = .002), and to have pleural or pericardial metastases (P < .05) compared with those with EGFR mutations. In multivariate analysis, lobulated margins (odds ratio, 4.815; 95% confidence interval [CI]: 1.789, 12.961; P = .002), N2 or N3 lymph node involvement (odds ratio, 2.445; 95% CI: 1.005, 5.950; P = .049), and lymphangitic lung metastasis (odds ratio, 8.485; 95% CI: 2.238, 32.170; P = .002) were more common in patients with ALK rearrangement than in those with EGFR mutation. The area under the receiver operating characteristic curve was 0.855.

Conclusion: Adenocarcinomas with ALK rearrangement appeared as solid masses with lobulated margins at CT and were more likely to be associated with lymphangitic metastasis, advanced lymph node metastasis, and pleural or pericardial metastasis than were tumors with EGFR mutations.
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http://dx.doi.org/10.1148/radiol.14140848DOI Listing
April 2015

Detailed analysis of the density change on chest CT of COPD using non-rigid registration of inspiration/expiration CT scans.

Eur Radiol 2015 Feb 14;25(2):541-9. Epub 2014 Sep 14.

Department of Radiology, Chonbuk National University Medical School and Hospital, Research Institute of Clinical Medicine, 20, Geonjiro Deokjin-gu, Jeonju-si, Jeollabuk-do, 561-712, Republic of Korea,

Objectives: One objective was to evaluate the air trapping index (ATI), measured by inspiration/expiration CT, in COPD patients and nonsmokers. Another objective was to assess the association between the pulmonary function test (PFT) and CT parameters such as ATI or other indices, separately in the whole lung, in emphysema, and in hyperinflated and normal lung areas.

Methods: One hundred and thirty-eight COPD patients and 29 nonsmokers were included in our study. The ATI, the emphysema index (EI), the gas trapping index (Exp -856) and expiration/inspiration ratio of mean lung density (E/Iratio of MLD) were measured on CT. The values of the whole lung, of emphysema, and of hyperinflated and normal lung areas were compared and then correlated with various PFT parameters.

Results: Compared with nonsmokers, COPD patients showed a higher ATI in the whole lung and in each lung lesion (all P < 0.05). The ATI showed a higher correlation than EI with FEF25-75%, RV and RV/TLC, and was comparable to Exp -856 and the E/I ratio of MLD. The ATI of emphysema and hyperinflated areas on CT showed better correlation than the normal lung area with PFT parameters.

Conclusions: Detailed analysis of density change at inspiration and expiration CT of COPD can provide new insights into pulmonary functional impairment in each lung area.

Key Points: • COPD patients show significant air trapping in the lung. • The air trapping index is a comparable parameter to other CT indices. • Air trapping of emphysema and hyperinflated lung areas relates to functional loss. • The emphysema area changes more, with less air trapping than other areas.
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http://dx.doi.org/10.1007/s00330-014-3418-0DOI Listing
February 2015

Nontuberculous mycobacterial pulmonary infection in patients with idiopathic interstitial pneumonias: comparison with patients without idiopathic interstitial pneumonias.

J Comput Assist Tomogr 2014 Nov-Dec;38(6):972-8

From the *Department of Radiology, Hallym University College of Medicine, Hallym University Sacred Heart Hospital, Gyeonggi-do; Departments of †Radiology and Research Institute of Radiology and ‡Pulmonary and Critical Care Medicine, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.

Objective: The aim of this study was to describe computed tomography (CT) findings of nontuberculous mycobacterial (NTM) pulmonary infection in patients with idiopathic interstitial pneumonias (IIP) in comparison with those in patients without IIP.

Methods: From November 2001 to October 2012, 810 patients in the NTM registry were retrospectively reviewed. Among them, 42 patients (mean age, 69.7 years; 32 men and 10 women) who were diagnosed as having IIP by either histological or radioclinical criteria were included in our study. Eighty-two age- and sex-matched immunocompetent patients with NTM pulmonary infection and without IIP were selected as the control group. Medical records and CT scans were reviewed. Formal radiologic reports obtained before diagnosis of NTM infection were also reviewed.

Results: Lobar/segmental consolidation (85.7%) was the most common CT finding in the IIP group, whereas branching centrilobular nodules (95.1%), traction bronchiectasis (79.3%), and volume decrease (58.5%) were common in the control group. Frequencies of these findings were significantly different between the 2 groups (P < 0.001). Most of consolidations were associated with cavity (83.3%) without dominant zonal distribution. Pneumonia or fungal infection (n = 20) was the most common radiologic diagnosis in the IIP group.

Conclusions: The NTM pulmonary infection in IIP patients is characterized as lobar/segmental consolidation with/without cavity, different to immunocompetent patients without IIP, and can mimic other diseases especially bacterial/fungal infection.
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http://dx.doi.org/10.1097/RCT.0000000000000144DOI Listing
January 2015

Assessment of perfusion pattern and extent of perfusion defect on dual-energy CT angiography: correlations between the causes of pulmonary hypertension and vascular parameters.

Korean J Radiol 2014 Mar-Apr;15(2):286-94. Epub 2014 Mar 7.

Department of Radiology, Seoul Medical Center, Seoul 131-865, Korea.

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.
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http://dx.doi.org/10.3348/kjr.2014.15.2.286DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3955797PMC
May 2014

Percutaneous CT-guided aspiration and core biopsy of pulmonary nodules smaller than 1 cm: analysis of outcomes of 305 procedures from a tertiary referral center.

AJR Am J Roentgenol 2013 Nov;201(5):964-70

1 All authors: Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, 86 Asanbyeongwon-Gil, Songpa-Gu, Seoul 138-736, Korea.

Objective: We conducted a retrospective analysis to evaluate the diagnostic outcomes of CT-guided aspiration and core biopsy of 305 pulmonary nodules measuring less than 1 cm.

Materials And Methods: We determined the diagnostic yield of using CT-guided aspiration and core biopsy to analyze 305 lesions in 290 patients. Diagnostic performance was evaluated according to the biopsy method, including aspiration alone, core biopsy alone, and combination use, and the consistency of the nodule, including solid, partly solid ground-glass opacity (GGO), and pure GGO. Final diagnoses were established in 268 of the 305 lesions (87.9%). Nondiagnostic biopsy results were obtained for 27 of the 268 lesions (10.1%).

Results: The overall sensitivity, specificity, positive predictive value, and negative predictive value for the diagnosis of malignancy were 93.1% (148 of 159 lesions), 98.8% (81/82), 99.3% (148/149), and 88.0% (81/92), respectively; diagnostic accuracy was 95.0% (229/241). Using multivariate logistic regression analysis, we found that aspiration alone was a significant independent risk factor associated with diagnostic failure (odds ratio, 3.199; p = 0.001).

Conclusion: The use of CT-guided aspiration and core biopsy resulted in a high diagnostic yield for pulmonary nodules smaller than 1 cm. The use of the aspiration method alone was an independent risk factor associated with diagnostic failure.
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http://dx.doi.org/10.2214/AJR.12.10156DOI Listing
November 2013

Low-dose chest computed tomography with sinogram-affirmed iterative reconstruction, iterative reconstruction in image space, and filtered back projection: studies on image quality.

J Comput Assist Tomogr 2013 Jul-Aug;37(4):610-7

Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Korea.

Objective: This study aimed to determine optimal strength of sinogram-affirmed iterative reconstruction (SAFIRE) and to evaluate image quality (IQ) of low-dose chest computed tomography (LDCT) using SAFIRE compared with iterative reconstruction in image space (IRIS) and filtered back projection (FBP).

Methods: Thirty patients underwent LDCT. Computed tomography (CT) was reconstructed using 5 strengths of SAFIRE (S1-S5), IRIS, and FBP. Objective noise of CT was measured. Two radiologists evaluated CT for subjective IQ, beam-hardening artifacts, and overall IQ.

Results: Measured noise was highest in FBP, followed by S1, S2, S3, IRIS, S4, and S5. S2 and S3 demonstrated significantly higher overall IQ scores than the other strengths (P < 0.05). Overall IQ and beam-hardening artifacts of S2 and S3 were significantly better than those in FBP and IRIS (P < 0.001).

Conclusions: S2 or S3 strengths of SAFIRE can be used practically in clinical routines and may have more potential than IRIS and FBP for LDCT with improved IQ.
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http://dx.doi.org/10.1097/RCT.0b013e31828f4daeDOI Listing
September 2013

Thoracic magnetic resonance imaging for the evaluation of pulmonary emphysema.

J Thorac Imaging 2013 May;28(3):160-70

Department of Radiology, University of Ulsan College of Medicine, Seoul, Korea.

Pulmonary emphysema is a pathologic condition characterized by permanently enlarged airspaces distal to the terminal bronchiole with destruction of the alveolar walls. Functional information of the lungs is important to understand the pathophysiology of emphysema and that of chronic obstructive pulmonary disease. With the recent developments in magnetic resonance imaging (MRI) techniques, functional MRI with variable MR sequences can be used for the evaluation of different physiological and anatomic changes seen in cases of pulmonary emphysema. In this review article, we will focus on a brief description of each method, results of some of the most recent work, and the clinical application of such knowledge.
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http://dx.doi.org/10.1097/RTI.0b013e31828d4087DOI Listing
May 2013

Prediction of postoperative lung function in patients undergoing lung resection: dual-energy perfusion computed tomography versus perfusion scintigraphy.

Invest Radiol 2013 Aug;48(8):622-7

Department of Radiology and Research Institute of Radiology, University of Ulsan College of Medicine, Asan Medical Center, Seoul, Republic of Korea.

Objectives: The purpose of this study was to assess the usefulness of dual-energy perfusion computed tomography (CT) for predicting postoperative lung function in patients undergoing lung resection.

Methods: Fifty-one patients (38 men, 13 women; mean age, 63.8 years) were prospectively enrolled and subsequently underwent dual-energy CT, perfusion scintigraphy, a pulmonary function test before surgery, and a pulmonary function test 6 months after surgery. Computed tomography was performed using dual-source CT with the dual-energy technique. Using weighted average images, each lobe was segmented and using perfusion images, the iodine value was quantitatively measured. Lobar perfusion was calculated by multiplying the volume of the lobe by the iodine value. The ratio of lobar perfusion per whole-lung perfusion was then calculated. The predicted postoperative forced expiratory volume during 1 second (post-FEV1) was calculated by multiplying the preoperative FEV1 by the fractional contribution of perfusion of the remaining lung. The agreement between the predicted post-FEV1 and the actual post-FEV1 was then evaluated. The percentage of error of the predicted post-FEV1 to that of the actual post-FEV1 was then calculated.

Results: Using the Bland-Altman method, the limits of agreement between the actual post-FEV1 and the predicted post-FEV1 were -29.3% and 26.9% for scintigraphy and -28.9% and 17.3% for CT. The percentage of error of CT (15.4%) was comparable with that of scintigraphy (17.8%).

Conclusions: Dual-energy perfusion CT was more accurate than perfusion scintigraphy was for predicting postoperative lung function.
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http://dx.doi.org/10.1097/RLI.0b013e318289fa55DOI Listing
August 2013