• Korean Journal of Radiology
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• 제21권4호
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• pp.402-412
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• 2020

Objective: To evaluate the performance of predicting early recurrence using preoperative factors only in comparison with using both pre-/postoperative factors. Materials and Methods: We retrospectively reviewed 549 patients who had undergone curative resection for single hepatcellular carcinoma (HCC) within Milan criteria. Multivariable analysis was performed to identify pre-/postoperative high-risk factors of early recurrence after hepatic resection for HCC. Two prediction models for early HCC recurrence determined by stepwise variable selection methods based on Akaike information criterion were built, either based on preoperative factors alone or both pre-/postoperative factors. Area under the curve (AUC) for each receiver operating characteristic curve of the two models was calculated, and the two curves were compared for non-inferiority testing. The predictive models of early HCC recurrence were internally validated by bootstrap resampling method. Results: Multivariable analysis on preoperative factors alone identified aspartate aminotransferase/platelet ratio index (OR, 1.632; 95% CI, 1.056-2.522; p = 0.027), tumor size (OR, 1.025; 95% CI, 0.002-1.049; p = 0.031), arterial rim enhancement of the tumor (OR, 2.350; 95% CI, 1.297-4.260; p = 0.005), and presence of nonhypervascular hepatobiliary hypointense nodules (OR, 1.983; 95% CI, 1.049-3.750; p = 0.035) on gadoxetic acid-enhanced magnetic resonance imaging as significant factors. After adding postoperative histopathologic factors, presence of microvascular invasion (OR, 1.868; 95% CI, 1.155-3.022; p = 0.011) became an additional significant factor, while tumor size became insignificant (p = 0.119). Comparison of the AUCs of the two models showed that the prediction model built on preoperative factors alone was not inferior to that including both pre-/postoperative factors {AUC for preoperative factors only, 0.673 (95% confidence interval [CI], 0.623-0.723) vs. AUC after adding postoperative factors, 0.691 (95% CI, 0.639-0.744); p = 0.0013}. Bootstrap resampling method showed that both the models were valid. Conclusion: Risk stratification solely based on preoperative imaging and laboratory factors was not inferior to that based on postoperative histopathologic risk factors in predicting early recurrence after curative resection in within Milan criteria single HCC patients.

• Korean Journal of Radiology
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• 제22권12호
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• pp.1964-1973
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• 2021

Objective: To investigate the diagnostic performance of CT fractional flow reserve (CT-FFR) for myocardial bridging-related ischemia using dynamic CT myocardial perfusion imaging (CT-MPI) as a reference standard. Materials and Methods: Dynamic CT-MPI and coronary CT angiography (CCTA) data obtained from 498 symptomatic patients were retrospectively reviewed. Seventy-five patients (mean age ± standard deviation, 62.7 ± 13.2 years; 48 males) who showed myocardial bridging in the left anterior descending artery without concomitant obstructive stenosis on the imaging were included. The change in CT-FFR across myocardial bridging (ΔCT-FFR, defined as the difference in CT-FFR values between the proximal and distal ends of the myocardial bridging) in different cardiac phases, as well as other anatomical parameters, were measured to evaluate their performance for diagnosing myocardial bridging-related myocardial ischemia using dynamic CT-MPI as the reference standard (myocardial blood flow < 100 mL/100 mL/min or myocardial blood flow ratio ≤ 0.8). Results: ΔCT-FFR_systolic (ΔCT-FFR calculated in the best systolic phase) was higher in patients with vs. without myocardial bridging-related myocardial ischemia (median [interquartile range], 0.12 [0.08-0.17] vs. 0.04 [0.01-0.07], p < 0.001), while CT-FFR_systolic (CT-FFR distal to the myocardial bridging calculated in the best systolic phase) was lower (0.85 [0.81-0.89] vs. 0.91 [0.88-0.96], p = 0.043). In contrast, ΔCT-FFR_diastolic (ΔCT-FFR calculated in the best diastolic phase) and CT-FFR_diastolic (CT-FFR distal to the myocardial bridging calculated in the best diastolic phase) did not differ significantly. Receiver operating characteristic curve analysis showed that ΔCT-FFR_systolic had largest area under the curve (0.822; 95% confidence interval, 0.717-0.901) for identifying myocardial bridging-related ischemia. ΔCT-FFR_systolic had the highest sensitivity (91.7%) and negative predictive value (NPV) (97.8%). ΔCT-FFR_diastolic had the highest specificity (85.7%) for diagnosing myocardial bridging-related ischemia. The positive predictive values of all CT-related parameters were low. Conclusion: ΔCT-FFR_systolic reliably excluded myocardial bridging-related ischemia with high sensitivity and NPV. Myocardial bridging showing positive CT-FFR results requires further evaluation.

• Korean Journal of Radiology
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• 제22권3호
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• pp.464-475
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• 2021

Objective: This study aimed to evaluate the tumor doubling time of invasive lung adenocarcinoma according to the International Association of the Study for Lung Cancer (IASLC)/American Thoracic Society (ATS)/European Respiratory Society (ERS) histologic classification. Materials and Methods: Among the 2905 patients with surgically resected lung adenocarcinoma, we retrospectively included 172 patients (mean age, 65.6 ± 9.0 years) who had paired thin-section non-contrast chest computed tomography (CT) scans at least 84 days apart with the same CT parameters, along with 10 patients with squamous cell carcinoma (mean age, 70.9 ± 7.4 years) for comparison. Three-dimensional semiautomatic segmentation of nodules was performed to calculate the volume doubling time (VDT), mass doubling time (MDT), and specific growth rate (SGR) of volume and mass. Multivariate linear regression, one-way analysis of variance, and receiver operating characteristic curve analyses were performed. Results: The median VDT and MDT of lung cancers were as follows: acinar, 603.2 and 639.5 days; lepidic, 1140.6 and 970.1 days; solid/micropapillary, 232.7 and 221.8 days; papillary, 599.0 and 624.3 days; invasive mucinous, 440.7 and 438.2 days; and squamous cell carcinoma, 149.1 and 146.1 days, respectively. The adjusted SGR of volume and mass of the solid-/micropapillary-predominant subtypes were significantly shorter than those of the acinar-, lepidic-, and papillary-predominant subtypes. The histologic subtype was independently associated with tumor doubling time. A VDT of 465.2 days and an MDT of 437.5 days yielded areas under the curve of 0.791 and 0.795, respectively, for distinguishing solid-/micropapillary-predominant subtypes from other subtypes of lung adenocarcinoma. Conclusion: The tumor doubling time of invasive lung adenocarcinoma differed according to the IASCL/ATS/ERS histologic classification.

• Korean Journal of Radiology
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• 제20권5호
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• pp.759-772
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• 2019

Objective: To investigate the value of ultrasound (US) microflow assessment in distinguishing malignant from benign solid breast masses as well as the association between US parameters and histologic microvessel density (MVD). Materials and Methods: Ninety-eight breast masses (57 benign and 41 malignant) were examined using Superb Microvascular Imaging (SMI) and contrast-enhanced US (CEUS) before biopsy. Two radiologists evaluated the quantitative and qualitative vascular parameters on SMI (vascular index, morphology, distribution, and penetration) and CEUS (time-intensity curve analysis and enhancement characteristics). US parameters were compared between benign and malignant masses and the diagnostic performance was compared between SMI and CEUS. Subgroup analysis was performed according to lesion size. The effect of vascular parameters on downgrading Breast Imaging Reporting and Data System (BI-RADS) category 4A masses was evaluated. The association between histologic MVD and US parameters was analyzed. Results: Malignant masses were associated with a higher vascular index (15.1 ± 7.3 vs. 5.9 ± 5.6), complex vessel morphology (82.9% vs. 42.1%), central vascularity (95.1% vs. 59.6%), penetrating vessels (80.5% vs. 31.6%) on SMI (all, p < 0.001), as well as higher peak intensity (37.1 ± 25.7 vs. 17.0 ± 15.8, p < 0.001), slope (10.6 ± 11.2 vs. 3.9 ± 4.2, p = 0.001), area (1035.7 ± 726.9 vs. 458.2 ± 410.2, p < 0.001), hyperenhancement (95.1% vs. 70.2%, p = 0.005), centripetal enhancement (70.7% vs. 45.6%, p = 0.023), penetrating vessels (65.9% vs. 22.8%, p < 0.001), and perfusion defects (31.7% vs. 3.5%, p < 0.001) on CEUS (p ≤ 0.023). The areas under the receiver operating characteristic curve (AUCs) of SMI and CEUS were 0.853 and 0.841, respectively (p = 0.803). In 19 masses measuring < 10 mm, central vascularity on SMI was associated with malignancy (100% vs. 38.5%, p = 0.018). Considering all benign SMI parameters on the BI-RADS assessment, unnecessary biopsies could be avoided in 12 category 4A masses with improved AUCs (0.500 vs. 0.605, p < 0.001). US vascular parameters associated with malignancy showed higher MVD (p ≤ 0.016). MVD was higher in malignant masses than in benign masses, and malignant masses negative for estrogen receptor or positive for Ki67 had higher MVD (p < 0.05). Conclusion: US microflow assessment using SMI and CEUS is valuable in distinguishing malignant from benign solid breast masses, and US vascular parameters are associated with histologic MVD.

• Korean Journal of Radiology
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• 제20권4호
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• pp.671-682
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• 2019

Objective: To investigate whether computed tomography (CT) and fluorine-18-labeled fluoro-2-deoxy-D-glucose (FDG) positron emission tomography (PET) may be applied to distinguish thymic epithelial tumors (TETs) from benign cysts in the anterior mediastinum. Materials and Methods: We included 262 consecutive patients with pathologically proven TETs and benign cysts 5 cm or smaller who underwent preoperative CT scans. In addition to conventional morphological and ancillary CT findings, the relationship between the lesion and the adjacent mediastinal pleura was evaluated qualitatively and quantitatively. Mean lesion attenuation was measured on CT images. The maximum standardized uptake value (SUVmax) was obtained with FDG-PET scans in 40 patients. CT predictors for TETs were identified with multivariate logistic regression analysis. For validation, we assessed the diagnostic accuracy and inter-observer agreement between four radiologists in a size-matched set of 24 cysts and 24 TETs using a receiver operating characteristic curve before and after being informed of the study findings. Results: The multivariate analysis showed that post-contrast attenuation of 60 Hounsfield unit or higher (odds ratio [OR], 12.734; 95% confidence interval [CI], 2.506-64.705; p = 0.002) and the presence of protrusion from the mediastinal pleura (OR, 9.855; 95% CI, 1.749-55.535; p = 0.009) were the strongest CT predictors for TETs. SUVmax was significantly higher in TETs than in cysts (5.3 ± 2.4 vs. 1.1 ± 0.3; p < 0.001). After being informed of the study findings, the readers' area under the curve improved from 0.872-0.955 to 0.949-0.999 (p = 0.066-0.149). Inter-observer kappa values for protrusion were 0.630-0.941. Conclusion: Post-contrast CT attenuation, protrusion from the mediastinal pleura, and SUVmax were useful imaging features for distinguishing TETs from cysts in the anterior mediastinum.

• Tuberculosis and Respiratory Diseases
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• 제64권4호
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• pp.266-271
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• 2008

연구배경: 급성 폐색전증의 발생을 예측하는 Wells 및 Geneva 예측 모형은 서구에서 잘 확립되어 있다. 폐색전증의 역학이 서구와 다를 것으로 보이는 국내에서의 예측모형의 유용성에 대해서 평가 하고자 한다. 방법: 단일 의료기관에서 폐색전증 의심 하에 multi-detector computed tomography (MDCT)를 시행한 환자 210명을 대상으로 후향적으로 조사하였다. 성별 구성은 남자 90명(42.9%), 여자 120명(57.1%)이었고, 평균 연령은 $63.3{\pm}15.9$세였다. 의무기록을 바탕으로 Wells 및 개정된 Geneva 예측 모형으로 폐색전증의 가능성에 대해 저위험군, 중등도 위험군, 고위험군으로 분류하였다. 결과: 폐색전증으로 진단된 환자는 210명 중 41명(19.5%)이었다. Wells 예측 모형을 적용한 폐색전증 발병 가능성 평가에서는, 2명(1%)이 저위험군, 137명(62.5%)이 중등도 위험군, 71명(3.8%)이 고위험군으로 분류되었고, 각 군에서 폐색전증의 발생률은 10%, 18.2%, 19.7%였다. 개정된 Geneva 예측 모형을 적용할 경우 44명(21%)이 저위험군, 160명(76.2%)이 중등도 위험군, 6명(2.8%)이 고위험군으로 분류되었고, 각 군에서 폐색전증의 발생률은 4.5%, 2.5%, 50%로 나타났다. Receiver operating characteristic (ROC) 곡선 분석에서 개정된 Geneva 예측 모형이 Wells 예측 모형에 비해 정확도가 높았다. 두 예측 모형 사이의 일치율은 불량했다($\kappa$ coefficient=0.06). 결론: 본 연구에서는 폐색전증이 의심되는 환자에서 개정된 Geneva 예측모형과 Wells 예측 모형으로 평가하여 두 모형 사이에 일치율이 불량하였으며, 개정된 Geneva 모형이 Wells 모형에 비해 폐색전증 진단 예측이 더 정확하였다.

• 대한핵의학회지
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• 제33권2호
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• pp.131-142
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• 1999

목적: 휴식 부하 심근관류 SPECT로 관상동맥질환을 진단하고 관상동맥협착을 찾을 때 게이트 SPECT 방법과 감쇠보정 후 관류 SPECT를 사용하면 특이도가 올라가서 진단 성능이 향상된다는 보고가 있다. 이 연구는 임상적으로 중간 정도의 관상동맥질환 유병 가능성을 보이는 환자에서 게이트 SPECT가 진단 성능을 향상시키는지 게이트 감쇠보정 SPECT를 시행하여 조사하였다. 대상 및 방법: 휴식기 T1-201 디피리다몰 부하 Tc-99m-MIBI SPECT를 할 때 둘 다 감쇠보정 영상을 얻고 Tc-99m-MIBI SPECT는 게이트 SPECT로 얻어 검사성능을 비교하였다. 혈관조영술로 진단된 단일 혈관질환 13명, 두 혈관질환 18명, 세 혈관질환 8명과 정상임을 확인한 29명을 합한 모두 68명의 환자에서 세 판독자가 독립적으로 각 동맥의 협착 유무와 질환 유무를 5 등급으로 점수화하여 수신자 특성 곡선을 그렸다. 결과: Hanley와 McNeil의 방법으로 곡선 아래 면적을 구하고 비교하여 유의한 차이가 있는지 보았으나 판독자나 어느 동맥영역인지에 상관없이 유의한 차이를 찾지 못하였다. 등급 3보다 큰 등급을 지정한 경우 검사 양성으로 보아 계산한 예민도와 특이도도 유의하게 차이 없었다. 결론: 우리는 이 결과를 보고 관상동맥질환의 검사 전 가능성이 중간 정도인 환자에서는 판독자나 동맥에 상관없이 게이트 SPECT를 더하거나 감쇠보정 SPECT를 더하여 보아도 진단 성능이 향상되지 않는다고 생각하였다.

• 정신신체의학
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• 제9권2호
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• pp.153-163
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• 2001

본 연구는 KEAT-26의 변별 타당도를 알아보고 이 척도의 진단적(분류적) 효율성을 알아보기 위해서 이루어졌다. 참여자는 여성 식사장애 환자 108명, 체형관리센터에서 체형관리프로그램에 참여하고 있는 여성 179명, 체대운동여학생 120명, 일반여자대학생 227명 그리고 일반여자 183명(총 817명)이었다. 변량분석과 ROC(Receiver Operating Characteristic Curve) 곡선 분석을 통해서 이 척도의 타당화를 시도하였다. 그 결과 KEAT-26 총점수가 집단간에 통계적으로 유의한 차이를 보였으며, 사후 검증에서 식사장애 환자집단이 다른 모든 집단보다 KEAT-26 점수가 유의하게 높았다. 그리고 각 집단에 따른 KEAT-26의 4 개 하위 요인점수의 차이 검증에서 모든 하위요인들에서 집단의 주 효과가 유의하였으나, 사후검증에서 요인 IV의 변별력이 떨어졌다. ROC 곡선 분석을 통하여 이 척도의 분류적인 효용성과 최대의 가질 때의 절단접수를 알아본 결과 식사장애 환자와 정상인 집단을 분류할 때 평균 약 80%이상의 효용성이 있으나 식사장애 고위험 집단을 변별할 때는 평균 약 69%의 효용성을 보였다. 특히, 최고의 효용성을 보일 때의 절단점수를 효면, 식사장애환자와 체형관리자를 분류할 때 절단점이 25점, 식사장애환자와 일반 여자를 분류할 때 분류점수는 19 점, 삭사장애환자 대 체대운동여학생의 분류 점수는 23점, 식사장애환자 대 일반여대생의 절단점은 21점이었다. 이민규 등(1998)이 제안한 T점수 65에 해당하는 KEAT-26의 총점 22점을 절단점수로 했을 때 이 척도의 민감도 54%, 특이도 84%, 효율성은 평균 80% 이었다. 본 연구 결과 KEAT-26온 한국 사람이 겪고 있는 식사문제에 관련된 연구에 필요한 신뢰롭고 타당한 도구임을 밝혀졌다. 또한 본 연구결과는 이 척도가 임상적인 이용 뿐 만 아니라 역학조사 동의 목적으로 식사문제가 있는 사람을 선별하는데도 유용한 도구임을 지지해 준다.

• 한국지리정보학회지
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• 제20권4호
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• pp.89-101
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• 2017

범죄는 장소나 건축물 용도에 따라 발생빈도와 유형이 다르고, 그 장소를 이용하는 사람들의 특성 및 공간 구조 차이에 의해 다양하게 발생한다. 따라서 공간 및 지역특성을 포함한 공간 빅데이터를 활용하여 지역을 분석해 보면 범죄예방 전략을 마련할 수 있다. 아울러 빅데이터와 지능 정보화시대의 도래에 따라 예측적 경찰활동이 새로운 경찰활동의 패러다임으로 등장하고 있다. 이에 보편적인 지방도시 J시를 대상으로 3개년 동안의 7,420건의 실제 범죄사례를 바탕으로 도시공간의 물리 환경적인 특성을 분석하여 범죄발생공간을 규명하고, 위험지역을 예측해 보고자 하였다. 분석에는 다양한 빅데이터 중 범죄를 유발하는 도시 공간 내 물리 환경적 요소에 한하여 공간 빅데이터를 구축하여 공간회귀분석을 실시하였다. 다음으로 분석결과 도출된 가로폭, 평균 층수, 용적율, 1층 사용용도(제2종 근린생활시설, 상업시설, 유흥시설, 주거시설)을 변수로 베이지안확률 기반 범죄발생 위험성 예측 모형(CIPM: Crime Incident Prediction Model)을 개발하였다. 개발된 모델은 실제 범죄발생 지역과의 중첩분석 및 모델의 정확도를 판단하는 Roc curve 분석을 통해 AUC 값이 0.8로 모델이 적합한 것으로 나타났다. 개발된 모델을 토대로 사례지역의 범죄 위험도를 분석한 결과 범죄발생은 상업 및 유흥시설이 밀집된 지역과 건물층수가 높은 지역, 그리고 상업 및 유흥시설과 주거가 혼재해 있는 블록이 범죄발생 확률이 높은 것으로 나타났다. 본 연구는 단순히 범죄의 공간적 분포와 범죄발생 영향요인을 탐색하는 기존의 연구와 달리 범죄발생 예측모델을 확률론적 관점에서 개발하는 영역으로 한 단계 진전되었다는 점에 의의가 있다.

• Tuberculosis and Respiratory Diseases
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• 제71권6호
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• pp.425-430
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• 2011

Background: High 2-[$^{18}F$] fluoro-2-deoxy-D-glucose (FDG) uptake on positron emission tomography-computed tomography (PET-CT) is a prognostic factor for poor survival in non-small cell lung cancer (NSCLC), especially in Stage I. We determined whether the high FDG uptake value of a primary tumor was associated with recurrence and death in patients with resected Stage I and Stage II NSCLC. Methods: We identified consecutive patients who underwent complete surgical resection for Stage I and II NSCLC between 2006 and 2009, who had preoperative PET-CT, and reviewed clinical records retrospectively. FDG uptake was measured as the maximal standardized uptake value (SUVmax) for body weight. Patients were divided into two groups based on SUVmax: (i) above or (ii) below the cut-off value (SUVmax=5.9) determined by a receiver operating characteristic (ROC) curve. Results: Of 57 patients who were enrolled consecutively, 32 (56%) had Stage I NSCLC and 25 (44%) had Stage II. The 5-year recurrence-free survival (RFS) for patients with high (${\geq}5.9$) and low (<5.9) SUVmax were 31% and 57%, respectively (p=0.014). The 5-year overall survival (OS) rates were 39% and 60%, respectively (p=0.029). In univariate analyses, SUVmax (p=0.014), T staging (p=0.025), and differentiation of tumor tissue (p=0.034) were significantly associated with RFS. But, multivariate analyses did not show that SUVmax was an independently significant factor for RFS (p=0.180). Conclusion: High FDG uptake on PET-CT is not an independent prognostic factor for poor outcomes (disease recurrence in patients with resected Stage I and II NSCLC).