Mi-Suk Shim

Seoul National University Hospital, Sŏul, Seoul, South Korea

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Publications (10)17.96 Total impact

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    ABSTRACT: To evaluate filtered back projection (FBP) and two iterative reconstruction (IR) algorithms and their effects on the quantitative analysis of lung parenchyma and airway measurements on computed tomography (CT) images. Low-dose chest CT obtained in 281 adult patients were reconstructed using three algorithms: FBP, adaptive statistical IR (ASIR) and model-based IR (MBIR). Measurements of each dataset were compared: total lung volume, emphysema index (EI), airway measurements of the lumen and wall area as well as average wall thickness. Accuracy of airway measurements of each algorithm was also evaluated using an airway phantom. EI using a threshold of -950 HU was significantly different among the three algorithms in decreasing order of FBP (2.30 %), ASIR (1.49 %) and MBIR (1.20 %) (P < 0.01). Wall thickness was also significantly different among the three algorithms with FBP (2.09 mm) demonstrating thicker walls than ASIR (2.00 mm) and MBIR (1.88 mm) (P < 0.01). Airway phantom analysis revealed that MBIR showed the most accurate value for airway measurements. The three algorithms presented different EIs and wall thicknesses, decreasing in the order of FBP, ASIR and MBIR. Thus, care should be taken in selecting the appropriate IR algorithm on quantitative analysis of the lung. • Computed tomography is increasingly used to provide objective measurements of intra-thoracic structures. • Iterative reconstruction algorithms can affect quantitative measurements of lung and airways. • Care should be taken in selecting reconstruction algorithms in longitudinal analysis. • Model-based iterative reconstruction seems to provide the most accurate airway measurements.
    European Radiology 11/2013; 24(4). DOI:10.1007/s00330-013-3078-5 · 4.34 Impact Factor
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    ABSTRACT: OBJECTIVE. The purpose of this article is to evaluate whether antiplatelet therapy increases the occurrence and severity of percutaneous transthoracic needle biopsy (PTNB)-related hemoptysis. MATERIALS AND METHODS. Our institutional review board approved this retrospective study, with waiver of informed consent. From May 2007 to December 2009, 1251 patients undergoing 1346 PTNBs constituted our study population. Of these PTNBs, 163 were performed in patients who had suspended antiplatelet therapy for less than 10 days (mean discontinuation time, 2.56 ± 2.35 days), and these patients were classified as antiplatelet agent users: 143 patients with single aspirin (mean discontinuation time, 2.55 ± 2.35 days), 12 patients with single clopidogrel (mean discontinuation time, 2.33 ± 2.10 days), and eight patients with dual-antiplatelet therapy (i.e., aspirin plus clopidogrel; mean discontinuation time, 3.12 ± 2.90 days). The influence of antiplatelet therapy on the occurrence and severity of PTNB-related hemoptysis was retrospectively evaluated. RESULTS. Among 1346 PTNBs, there were 128 cases (9.5%) of hemoptysis, including 21 cases of severe hemoptysis (1.6%). Multivariate analysis revealed that dual-antiplatelet therapy (odds ratio [OR], 10.09), female sex (OR, 1.88), smaller lesions (OR, 0.88), deeply located lesions (OR, 1.17), and the use of cutting needles (OR, 3.22) were independent risk factors for overall hemoptysis. For severe hemoptysis, dual-antiplatelet therapy (OR, 13.02), ground-glass nodules (OR, 8.86), and deeply located lesions (OR, 1.24) were proven to be independent risk factors. Single-antiplatelet therapy suspended for less than 10 days was not a significant risk factor for either overall or severe hemoptysis. CONCLUSION. Single-antiplatelet therapy suspended for less than 10 days is not an independent risk factor for the occurrence of PTNB-related hemoptysis, whereas dual-antiplatelet therapy increases its risk.
    American Journal of Roentgenology 05/2013; 200(5):1014-9. DOI:10.2214/AJR.12.8931 · 2.74 Impact Factor
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    ABSTRACT: PURPOSE Antiplatelet therapy may aggravate the occurrence and severity of percutaneous transthoracic lung biopsy (PTLB)-related hemoptysis. Thus, the impact of antiplatelet therapy on PTLB-related hemoptysis needs to be studied for proper management. METHOD AND MATERIALS 1346 PTLBs in 1251 patients constituted our study population. Among them, 163 PTLBs were performed in patients treated with antiplatelet therapy: 143 patients with single aspirin, 12 patients with single clopidogrel and 8 patients with dual antiplatelet therapy, aspirin plus clopidogrel. Their influence on the occurrence and severity of PTLB-related hemoptysis was retrospectively evaluated. RESULTS Among 1346 PTLBs, there were 128 (9.5%) cases of hemoptysis including 21 severe hemoptysis (1.5%). Multivariate analysis revealed DAT (odds ratio (OR), 10.09), female sex (OR, 1.88), smaller lesions (OR, 0.88), deeply-located lesions (OR, 1.17) and use of cutting needles (OR, 3.22) were independent risk factors for overall hemoptysis. For severe hemoptysis, DAT (OR, 13.02), ground-glass nodules (OR, 8.86) and deeply-located lesions (OR, 1.24) were proven to be independent risk factors. Single aspirin or clopidogrel was not a significant risk factor for either overall or severe hemoptysis. CONCLUSION Our results revealed that single antiplatelet therapy is not an independent risk factor for the occurrence of PTLB-related hemoptysis, whereas DAT increases risk. CLINICAL RELEVANCE/APPLICATION Patients who receive DAT with aspirin plus clopidogrel and are planning to undergo PCNB should be considered to discontinue antiplatelet therapy prior to PCNB if it can be done safely.
    Radiological Society of North America 2012 Scientific Assembly and Annual Meeting; 11/2012
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    ABSTRACT: The purpose of this study is to retrospectively evaluate the diagnostic accuracy and complications of C-arm cone-beam CT (CBCT)-guided percutaneous transthoracic needle biopsy (PTNB) for small (≤ 20 mm) lung nodules and their possible influencing factors. From March 2009 to July 2010, 161 consecutive patients (77 men and 84 women; mean [± SD] age, 61 ± 11.8 years; range, 29-85 years) with 173 small (≤ 20 mm) lung nodules underwent CBCT-guided PTNB performed by an experienced chest radiologist in a tertiary referral hospital. The diagnostic accuracy, sensitivity, specificity, and complication rates were statistically evaluated, and influencing factors were assessed using univariate and subsequent multivariate analysis. Of 173 nodules (mean size, 15 ± 3.7 mm), 94 (54.3%) were diagnosed as malignant, 69 (39.9%) as benign, and 10 (5.8%) as indeterminate. On PTNB, 160 nodules were correctly diagnosed and three were false-negatives. Diagnostic accuracy, sensitivity, and specificity were 98.2%, 96.8%, and 100%, respectively. No factors significantly decreased diagnostic accuracy. As for complications, pneumothorax, hemoptysis, and chest pain occurred in 55 (31.8%), 25 (14.5%), and two (1.2%) patients, respectively. Multivariate analysis revealed that the presence of emphysema along the needle pathway was a significant risk factor (odds ratio [OR], 10.11), and the occurrence of hemoptysis was a significant protective factor (OR, 0.28) against pneumothorax. Ground-glass nodules were found to be a significant independent risk factor for hemoptysis (OR, 5.10). C-arm CBCT-guided PTNB is highly accurate for small lung nodules, and the diagnostic accuracy does not significantly decrease even in technically challenging conditions.
    American Journal of Roentgenology 09/2012; 199(3):W322-30. DOI:10.2214/AJR.11.7576 · 2.74 Impact Factor
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    ABSTRACT: The aim of this study was to evaluate whether a computer-aided diagnosis (CAD) system improves interobserver agreement in the interpretation of lung nodules at low-dose computed tomography (CT) screening for lung cancer. Baseline low-dose screening CT examinations from 134 participants enrolled in the National Lung Screening Trial were reviewed by 7 chest radiologists. All participants consented to the use of their deidentified images for research purposes. Screening results were classified as positive when noncalcified nodules larger than 4 mm in diameter were present. Follow-up evaluation was recommended according to the nodule diameter: 4 mm or smaller, more than 4 to 8 mm, and larger than 8 mm. When multiple nodules were present, recommendations were based on the largest nodule. Readers initially assessed the nodule presence visually and measured the average nodule diameter manually. Revision of their decisions after reviewing the CAD marks and size measurement was allowed. Interobserver agreement evaluated using multirater κ statistics was compared between initial assessment and that with CAD. Multirater κ values for the positivity of the screening results and follow-up recommendations were improved from moderate (κ = 0.53-0.54) at initial assessment to good (κ = 0.66-0.67) after reviewing CAD results. The average percentage of agreement between reader pairs on the positivity of screening results and follow-up recommendations per case was also increased from 77% and 72% at initial assessment to 84% and 80% with CAD, respectively. Computer-aided diagnosis may improve the reader agreement on the positivity of screening results and follow-up recommendations in the assessment of low-dose screening CT.
    Investigative radiology 06/2012; 47(8):457-61. DOI:10.1097/RLI.0b013e318250a5aa · 4.45 Impact Factor
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    ABSTRACT: PURPOSE To investigate the incidence of early, delayed, and progressive pneumothorax after PCNB of the lung using the C-arm cone beam CT (CBCT) system, and to analyze the risk factors affecting each type of pneumothorax. METHOD AND MATERIALS From December 2008 to December 2010, 410 consecutive patients underwent CBCT-guided PCNB of the lung using the coaxial core biopsy technique. The incidence and risk factors of early, delayed and progressive pneumothorax associated with CBCT-guided PCNB were investigated. Early pneumothorax was defined as pneumothorax occurring during or immediately after PCNB. Delayed pneumothorax was defined as pneumothorax newly occurring on follow-up after PCNB. And progressive pneumothorax was a case of early pneumothorax which progressed during follow-up. Univariate and multivariate analyses were performed to evaluate risk factors for each type of pneumothorax. RESULTS Pneumothorax occurred in 143 (34.9%) of 410 patients; early pneumothorax in 123 patients (30%) and delayed pneumothorax in 20 (4.9%). Progressive pneumothorax occurred in 23 patients (5.6%) comprising 18.7% of early pneumothorax. Chest drainage catheters were needed in 12 (2.9%) of the 410 patients. Multivariate analysis revealed that male sex (adjusted odds ratio (OR), 1.680), old age (OR, 1.037) and emphysema in the needle path (OR, 4.48) were significant independent risk factors, and occurrence of hemoptysis (OR, 0.499) was a significant protective factor for early pneumothorax. Significant risk factors for delayed pneumothorax were small lesion size (OR, 0.59) and emphysema in the needle path (OR, 5.612). There were no significant predictive factors for progressive pneumothorax. CONCLUSION Early pneumothorax is the most common type of pneumothorax associated with CBCT-guided PCNB, and for each type of pneumothorax, there are different risk factors affecting their occurrence. CLINICAL RELEVANCE/APPLICATION The occurrence of early and delayed pneumothorax can be predicted in advance and therefore, high risk patients for each type of pneumothorax can be more safely managed.
    Radiological Society of North America 2011 Scientific Assembly and Annual Meeting; 12/2011
  • Ho Young Hwang · Mi-Suk Shim · Eun-Ah Park · Hyuk Ahn
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    ABSTRACT: The outcomes of reduction ascending aortoplasty (RAA) performed with aortic valve surgery were evaluated and the results of RAA in patients with bicuspid aortic valve (BAV) were compared with those in patients with tricuspid valve. From October 1994 to April 2009, 88 patients underwent RAA. Aortic valve was bicuspid in 45 patients (BAV group) and tricuspid in 43 patients (TAV group). Total circulatory arrest was required in 45 patients. Preoperative ascending aortic diameter was 45.5±4.7mm. Early mortality rate was 1.1%. Ten-year survival rate and freedom from cardiac death were 91.1% and 96.2%, respectively. No differences in clinical outcomes were found between the 2 groups. No aorta-related complications including aortic rupture, dissection and reoperation were observed. Aortic diameter at the last follow-up (61±43 months) was 37.8±4.3mm. The interval between surgery and follow-up CTA was associated with aneurysmal recurrence (P=0.022). Average rate of dilatation was 0.42±0.49mm/year (n=37). A need for total circulatory arrest was associated with an increase of the aortic diameter (P=0.009). BAV was associated with neither aneurysmal recurrence nor increase of aortic diameter. RAA in patients with an ascending aortic aneurysm combined with aortic valve disease could be performed with acceptable early and long-term outcomes, even in patients with BAV. Long-term follow-up evaluation might be necessary due to the risk of redilatation especially in patients with an extended aneurysm, which required total circulatory arrest for RAA.
    Circulation Journal 02/2011; 75(2):322-8. DOI:10.1253/circj.CJ-10-0792 · 3.69 Impact Factor
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    ABSTRACT: PURPOSE To investigate the bronchodilator responsiveness of air-trappings based on ventilation defects seen on xenon-enhanced chest CT METHOD AND MATERIALS A total of 68 non-smokers with positive methacholine tests underwent pre-enhanced(inspiration and expiration) and xenon-enhanced chest CTs(basal and after salbutamol). Among them, 20 lobes in 15 patients(21–75 years: mean age 57.06 years, M:F=3:14) showing air-trappings were enrolled. Ventilation defects and their responsiveness after salbutamol treatment(group A: negative, group B: positive) were visually analyzed by two chest radiologists in consensus. We measured the HUs of air-trapping areas and adjacent normal lung parenchyma on both inspiration and expiration images. Total lung volumes(TLVs), lobar lung volumes(LLVs), lobar xenon ventilation index(LXVI, 0-40HU/lobe volume), and lobar emphysema index(LEI, -950HU, -910HU, -856HU) were calculated. RESULTS All air-trapping areas were seen as xenon ventilation defects(A=8, B=12). LLV significantly increased after salbutamol treatment(A,605±214, 690±203, P<0.001, B, 877±366, 1070±299, P=0.03) whereas LXVI was not significantly changed(A, 91±5, 93±5, p=0.45, B,89±10, 91±6, P= 0.41) in both groups. Mean HU of air-trappings in both inspiration(A,-922±27, B,-896±22, P= 0.03) and expiration(A,-902±30, B,-819±49, P<0.001) significantly increased in group B. Mean HU of adjacent normal lung parenchyma on inspiration(A,-866±31, B,-868±22, P>0.05) was not significantly different between the two groups, however, on expiration, it significantly increased in group B(A,-762±103, B,-647±81, P=0.01). Only the LEI using -856HU on expiration was significantly(A,28.19±22.08, B,5.93±3.05, P<0.05) decreased in group B. Bronchodilator responsiveness for air-trapping was able to be predicted through discriminant analysis; Group(A,-1.337, B,0.892)=14.497-(0.035*expiratory EI using -856HU)-(0.001* HU of air-trapping on inspiration)+(0.018* HU of air-trapping on expiration). By this equation, 95% of the original groups were correctly classified. CONCLUSION Bronchodilator responsiveness of air-trappings based on xenon-enhanced CT may be predicted using expiratory LEI of -856 HU, and HUs on inspiration and expiration images. CLINICAL RELEVANCE/APPLICATION For the treatment and assessment of patients with asthma, bronchodilator responsive air-trappings can be predicted with -856HU LEI and CT HUs based on distal airflow changes on xenon-enhanced CT.
    Radiological Society of North America 2010 Scientific Assembly and Annual Meeting; 12/2010
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    ABSTRACT: PURPOSE To investigate the diagnostic accuracy of C-arm cone beam CT (CBCT)-guided percutaneous transthoracic needle biopsy (PCNB) of small (≤20 mm) lung nodules and to evaluate the incidence of consequent pneumothorax and their influencing factors. METHOD AND MATERIALS One hundred thirty-five consecutive patients (67 men and 68 women; mean age, 59.4 years; range, 29–83 years) with 135 small (≤20 mm) pulmonary nodules underwent CBCT-guided PCNB using the coaxial core biopsy technique. Overall diagnostic accuracy, sensitivity, specificity, and pneumothorax rate were calculated and factors influencing the diagnostic accuracy and pneumothorax rate were statistically evaluated. RESULTS Sixty-six nodules (48.9%) were diagnosed as malignant, 59 (43.7%) as benign, and 10 (7.4%) as indeterminate. In PCNB, 122 nodules (15.2 ± 0.36mm) were correctly diagnosed and 3 nodules (13.7 ±0.32mm) were false negatives. Diagnostic accuracy, sensitivity, specificity, and incidence of pneumothorax were 98.4%, 95.5%, 100% and 28.1%, respectively. Nodule size, lesion depth from the pleura, and other factors did not influence the diagnostic accuracy of CBCT-guided PCNB. As for the pneumothorax rate, there were significant differences between the pneumothorax group and non-pneumothorax group regarding the presence of emphysema in the same lobe, emphysema in the needle path, pleural passage number, and occurrence of hemoptysis (p< 0.05). Multivariate analysis revealed that pleural passage number (adjusted odds ratio (OR), 3.31), and age (OR, 1.05) were significant risk factors, however the occurrence of hemoptysis (OR, 0.14) was significant protective factor for pneumothorax. CONCLUSION CBCT-guided PCNB is a very accurate diagnostic tool for small (≤20 mm) lung nodules, and even for subcentimeter nodules. As for pneumothorax, pleural passage number and old age were the significant risk factors. CLINICAL RELEVANCE/APPLICATION CBCT-guided PCNB is a very accurate diagnostic tool for small lung nodules and has enough potential to replace current image-guided PCNB using fluoroscopy or conventional CT.
    Radiological Society of North America 2010 Scientific Assembly and Annual Meeting; 12/2010
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    ABSTRACT: PURPOSE To correlate tumor response evaluated using RECIST criteria, FDG-PET and volumetric perfusion CT in patients with advanced lung cancer treated with first-line systemic combination chemotherapy METHOD AND MATERIALS 35 consecutive patients (M:F=23:12, mean age 64) with advanced lung cancer prospectively underwent whole-body CT, whole-body FDG-PET/CT, and adaptive 4D volumetric perfusion CT for primary lung mass before and after first two cycles of combination chemotherapy using gemcitabine and cisplatin. On whole-body CT, response to treatment was evaluated according to RECIST criteria (tumor size measurement). On FDG-PET, response was evaluated by measurement of change in SUVmax in the same lesions that had been defined as RECIST target lesions. On volumetric perfusion CT, change in blood flow, blood volume, and permeability of primary lung cancer mass was evaluated. Tumor response was considered to be positive in each modality when there was a > 30% decrease in tumor diameter, a > 25% decrease in SUVmax, and a > 25% decrease in one of perfusion parameters. Spearman rank correlation analysis was performed and rate of agreement in tumor response was calculated to correlate tumor responses evaluated by different modalities. RESULTS Change in tumor diameters in each patient was from 83% decrease to 53% increase (mean 19% decrease). Change in SUVmax was from 68% decrease to 90% increase (mean 7% decrease). Change in blood flow, blood volume, and permeability of primary lung cancer mass was from 43% decrease to 287% increase (mean 29% decrease), from 61% decrease to 116% increase (mean 11% decrease), and from 47% decrease to 64% increase (mean 5% decrease), respectively. Positive tumor response was found in 9 patients by RECIST, 11 patients by FDG-PET, and 10 patients by perfusion CT. Spearman correlation coefficient between tumor responses evaluated using different modalities was from -0.28 to 0.32. Rate of agreement in tumor response was 63% between RECIST and FDG-PET, 54% between RECIST and perfusion CT, and 51% between FDG-PET and perfusion CT. CONCLUSION Tumor responses evaluated by RECIST, FDG-PET and volumetric perfusion CT showed poor to fair correlation. CLINICAL RELEVANCE/APPLICATION Correlation of tumor response of different imaging modalities may help to establish a new guideline for evaluation of tumor response using various imaging modalities.
    Radiological Society of North America 2010 Scientific Assembly and Annual Meeting; 11/2010