Abstract 

Objective

This study aimed to compare the prognostic performance of Coronary Artery Disease (CAD)-Reporting and Data System (CAD-RADS) score with those of clinical risk factors and the extent of CAD classification for predicting major adverse cardiac events in emergency department patients.

Methods

A total of 779 patients with acute chest pain at low to intermediate risk for CAD underwent cardiac computed tomography angiography. The primary end point was early and late major adverse cardiac events. We developed the following models: model 1, clinical risk factors; model 2, clinical risk factors and CAD-RADS scores; model 3, clinical risk factors and extent of CAD.

Results

The C-statistics revealed that both CAD-RADS score and CAD extent improved risk stratification over the clinical risk factors (C-index for early events: C-index: 0.901 vs 0.814 and 0.911 vs 0.814; C-index for late events: 0.897 vs 0.808 and 0.905 vs 0.808; all P < 0.05).

Conclusions

The CAD-RADS score had additional risk prediction benefits over clinical risk factors for emergency department patients.

Journal: Journal of Computer Assisted Tomography

Author

Jiwoo Park, Jin Hur, Kyunghwa Han, Dong Jin Im, Kye Ho Lee, Young Joo Suh, Yoo Jin Hong, Hye-Jeong Lee, Young Jin Kim, Byoung Wook Choi

DOI: 10.1097/RCT.0000000000001153

Abstract

Objectives

To identify the optimal artery-based method for ordinal grading of coronary artery calcium (CAC) on non-electrocardiogram (ECG)-gated low-dose chest computed tomography (LDCT) among three methods.

Methods

A total of 120 asymptomatic subjects who underwent both LDCT and ECG-gated calcium scoring CT on the same day were retrospectively enrolled. Three cardiothoracic radiologists independently assessed CAC severity on LDCT (1.25-mm and 2.5-mm slice thickness) and classified it into four categories (none, mild, moderate, or severe) using three artery-based ordinal scoring methods (extent-based scoring, Weston scoring, and length-based scoring). Inter- and intra-observer CAC severity agreements of each method were assessed by Fleiss kappa statistics. Agreements between each method and ECG-gated calcium scoring CT were assessed by weighted kappa statistics.

Results

The inter-observer agreement was highest with length-based method for both 1.25-mm (Fleiss kappa 0.735 for extent-based method, 0.801 for Weston score, and 0.813 for length-based method) and 2.5-mm slice thickness evaluation (Fleiss kappa 0.755 for extent-based method, 0.776 for Weston score, and 0.833 for extent-based method). Agreement across the three grading methods for the same observer was poor to moderate on 1.25-mm (Fleiss kappa 0.379–0.441) and moderate on 2.5-mm thickness evaluation (Fleiss kappa 0.427–0.461). Agreement of CAC severity between each method and ECG-gated calcium scoring CT was highest with the length-based method for all three observers on both 1.25-mm (weighted kappa 0.773–0.786) and 2.5-mm (weighted kappa 0.794–0.825) LDCT images.

Conclusion

Among the three artery-based ordinal grading methods, the length-based method appears to be the most reliable for evaluating CAC on non-ECG-gated LDCT.

Key Points

• The length-based method showed the highest inter-observer agreement and the highest agreement with the ECG-gated calcium scoring CT, compared with the extent-based method and the Weston score.

Journal: European Radiology

Author

Suji Lee, Young Joo Suh, Kyungsun Nam, Kyeho Lee, Hye-Jeong Lee, and Byoung Wook Choi 

DOI: doi.org/10.1007/s00330-021-07987-7

Abstract 

Objective

The purpose of this meta-analysis was to investigate the pooled agreements of the coronary artery calcium (CAC) severities assessed by electrocardiogram (ECG)-gated and non-ECG-gated CT and evaluate the impact of the scan parameters.

Materials and Methods

PubMed, EMBASE, and the Cochrane library were systematically searched. A modified Quality Assessment of Diagnostic Accuracy Studies-2 tool was used to evaluate the quality of the studies. Meta-analytic methods were utilized to determine the pooled weighted bias, limits of agreement (LOA), and the correlation coefficient of the CAC scores or the weighted kappa for the categorization of the CAC severities detected by the two modalities. The heterogeneity among the studies was also assessed. Subgroup analyses were performed based on factors that could affect the measurement of the CAC score and severity: slice thickness, reconstruction kernel, and radiation dose for non-ECG-gated CT.

Results

A total of 4000 patients from 16 studies were included. The pooled bias was 62.60, 95% LOA were −36.19 to 161.40, and the pooled correlation coefficient was 0.94 (95% confidence interval [CI] = 0.89–0.97) for the CAC score. The pooled weighted kappa of the CAC severity was 0.85 (95% CI = 0.79–0.91). Heterogeneity was observed in the studies (I2 > 50%, p < 0.1). In the subgroup analysis, the agreement between the CAC categorizations was better when the two CT examinations had reconstructions based on the same slice thickness and kernel.

Conclusion

The pooled agreement of the CAC severities assessed by the ECG-gated and non-ECG-gated CT was excellent; however, it was significantly affected by scan parameters, such as slice thickness and the reconstruction kernel.

Keywords

Coronary artery calcium; Computed tomography; Reliability; Meta-analysis

Journal: Korean Journal of Radiology

Author

Jin Young Kim, Young Joo Suh, Kyunghwa Han, and Byoung Wook Choi

DOI: 10.3348/kjr.2020.1047

Abstract 

Background

Right ventricular (RV) free wall fibrosis is an important component of adverse remodeling with RV dysfunction in pulmonary hypertension (PH). However, no previous reports have compared cardiovascular magnetic resonance (CMR) findings and histological analysis for RV free wall fibrosis in PH. We aimed to assess the feasibility of CMR T1 mapping with extracellular volume fraction (ECV) for evaluating the progression of RV free wall fibrosis in PH, and compared imaging findings to histological collagen density through an animal study.

Methods

Among 42 6-week-old Wistar male rats, 30 were classified according to disease duration (baseline before monocrotaline injection, and 2, 4, 6 and 8 weeks after injection) and 12 were used to control for aging (4 and 8 weeks after the baseline). We obtained pre and post-contrast T1 maps for native T1 and ECV of RV and left ventricular (LV) free wall for six animals in each disease-duration group. Collagen density of RV free wall was calculated with Masson's trichrome staining. The Kruskall-Wallis test was performed to compare the groups. Native T1 and ECV to collagen density were analyzed with Spearman's correlation.

Results

The mean values of native T1, ECV and collagen density of the RV free wall at baseline were 1541 ± 33 ms, 17.2 ± 1.3%, and 4.7 ± 0.5%, respectively. The values of RV free wall did not differ according to aging (P = 0.244, 0.504 and 0.331, respectively). However, the values significantly increased according to disease duration (P < 0.001 for all). Significant correlations were observed between native T1 and collagen density (r = 0.770, P < 0.001), and between ECV and collagen density for the RV free wall (r = 0.815, P < 0.001) in PH. However, there was no significant difference in native T1 and ECV values for the LV free wall according to the disease duration from the baseline (P = 0.349 and 0.240, respectively).

Conclusions

We observed significantly increased values for native T1 and ECV of the RV free wall without significant increase of the LV free wall according to the disease duration of PH, and findings were well correlated with histological collagen density.

Journal: Journal of Cardiovascular Magnetic Resonance

Author

Pan Ki Kim, Yoo Jin Hong, Hyo Sub Shim, Dong Jin Im, Young Joo Suh, Kye Ho Lee, Jin Hur, Young Jin Kim, Byoung Wook Choi, and Hye-Jeong Lee

DOI: doi.org/10.1186/s12968-021-00755-y

Abstract 

Background

Chemotherapy-induced cardiotoxicity is a well-recognized adverse effect of chemotherapy. Quantitative T1-mapping cardiovascular magnetic resonance (CMR) is useful for detecting subclinical myocardial changes in anthracycline-induced cardiotoxicity. The aim of the present study was to histopathologically validate the T1 and T2 mapping parameters for the evaluation of diffuse myocardial changes in rat models of cardiotoxicity.

Methods

Rat models of cardiotoxicity were generated by injecting rats with doxorubicin (1 mg/kg, twice a week). CMR was performed with a 9.4 T ultrahigh-field scanner using cine, pre-T1, post-T1 and T2 mapping sequences to evaluate the left ventricular ejection fraction (LVEF), native T1, T2, and extracellular volume fraction (ECV). Histopathological examinations were performed and the association of histopathological changes with CMR parameters was assessed.

Results

Five control rats and 36 doxorubicin-treated rats were included and classified into treatment periods. In the doxorubicin-treated rats, the LVEF significantly decreased after 12 weeks of treatment (control vs. 12-week treated: 73 ± 4% vs. 59 ± 9%, P = 0.01).  Increased native T1 and ECV were observed after 6 weeks of treatment (control vs. 6-week treated: 1148 ± 58 ms, 14.3 ± 1% vs. 1320 ± 56 ms, 20.3 ± 3%; P = 0.005, < 0.05, respectively). T2 values also increased by six weeks of treatment (control vs. 6-week treated: 16.3 ± 2 ms vs. 10.3 ± 1 ms, P < 0.05). The main histopathological features were myocardial injury, interstitial fibrosis, inflammation, and edema. The mean vacuolar change (%), fibrosis (%), and inflammation score were significantly higher in 6-week treated rats than in the controls (P = 0.03, 0.03, 0.02, respectively). In the univariable analysis, vacuolar change showed the highest correlation with native T1 value (R = 0.60, P < 0.001), and fibrosis showed the highest correlation with ECV value (R = 0.78, P < 0.001). In the multiple linear regression analysis model, vacuolar change was a significant factor for change in native T1 (P = 0.01), and vacuolar change and fibrosis were significant factors for change in ECV (P = 0.006, P < 0.001, respectively) by adding other histopathological parameters (i.e., inflammation and edema scores)

Conclusions

Quantitative T1 and T2 mapping CMR is a useful non-invasive tool reflecting subclinical histopathological changes in anthracycline-induced cardiotoxicity.

Journal: Journal of Cardiovascular Magnetic Resonance

Author

Heae Surng Park, Yoo Jin Hong, Kyunghwa Han, Pan Ki Kim, Eunkyung An, Ji Yeon Lee, Chul Hwan Park, Hye-Jeong Lee, Jin Hur, Young Jin Kim, and Byoung Wook Choi

DOI: doi.org/10.1186/s12968-021-00767-8

Abstract 

Objective

This study aimed to investigate the regional amyloid burden and myocardial deformation using T1 mapping and strain values in patients with cardiac amyloidosis (CA) according to late gadolinium enhancement (LGE) patterns.

Materials and Methods

Forty patients with CA were divided into 2 groups per LGE pattern, and 15 healthy subjects were enrolled. Global and regional native T1 and T2 mapping, extracellular volume (ECV), and cardiac magnetic resonance (CMR)-feature tracking strain values were compared in an intergroup and interregional manner.

Results

Of the patients with CA, 32 had diffuse global LGE (group 2), and 8 had focal patchy or no LGE (group 1). Global native T1, T2, and ECV were significantly higher in groups 1 and 2 than in the control group (native T1: 1384.4 ms vs. 1466.8 ms vs. 1230.5 ms; T2: 53.8 ms vs. 54.2 ms vs. 48.9 ms; and ECV: 36.9% vs. 51.4% vs. 26.0%, respectively; all, p < 0.001). Basal ECV (53.7%) was significantly higher than the mid and apical ECVs (50.1% and 50.0%, respectively; p < 0.001) in group 2. Basal and mid peak radial strains (PRSs) and peak circumferential strains (PCSs) were significantly lower than the apical PRS and PCS, respectively (PRS, 15.6% vs. 16.7% vs. 26.9%; and PCS, −9.7% vs. −10.9% vs. −15.0%; all, p < 0.001). Basal ECV and basal strain (2-dimensional PRS) in group 2 showed a significant negative correlation (r = −0.623, p < 0.001). Group 1 showed no regional ECV differences (basal, 37.0%; mid, 35.9%; and apical, 38.3%; p = 0.184).

Conclusion

Quantitative T1 mapping parameters such as native T1 and ECV may help diagnose early CA. ECV, in particular, can reflect regional differences in the amyloid deposition in patients with advanced CA, and increased basal ECV is related to decreased basal strain. Therefore, quantitative CMR parameters may help diagnose CA and determine its severity in patients with or without LGE.

Keywords

Magnetic resonance imaging; Myocardium; Heart; Mapping; Extracellular space; Feature tracking

Journal: Korean Journal of Radiology

Author

Jin Young Kim, Yoo Jin Hong, Kyunghwa Han, Hye-Jeong Lee, Jin Hur, Young Jin Kim, and Byoung Wook Choi

DOI: 10.3348/kjr.2020.0579

Abstract 

Purpose

We aimed to develop a deep learning (DL)-based algorithm for automated quantification of aortic valve calcium (AVC) from non-enhanced electrocardiogram-gated cardiac CT scans and compare performance of DL-measured AVC volume and Agatston score with those of visual gradings by radiologist readers for classification of AVC severity.

Method

A total of 589 CT examinations performed at a single center between March 2010 and August 2017 were retrospectively included. The DL algorithm was designed to segment AVC and to quantify AVC volume, and Agatston score was calculated using attenuation values. Manually measured AVC volume and Agatston score were used as ground truth. To validate AVC segmentation performance, the Dice coefficient was calculated. For observer performance testing, four radiologists determined AVC grade in two reading rounds. The diagnostic performance of DL-measured AVC volume and Agaston score for classifying severe AVC was compared with that of each reader’s assessment.

Results

After applying the DL algorithm, the Dice coefficient score was 0.807. In patients with AVC, accuracy of DL-measured AVC volume for AVC grading was 97.0 % with area under the curve (AUC) of 0.964 (95 % confidence interval [CI] 0.923–1) in the test set, which was better than the radiologist readers (accuracy 69.7 %–91.9 %, AUC 0.762–0.923) with manually measured AVC volume as ground truth. When manually measured AVC Agatston score was used as ground truth, accuracy of DL-measured AVC Agatston score for AVC grading was 92.9 % with AUC of 0.933 (95 % CI 0.885–0.981) in the test set, which was also better than the radiologist readers (accuracy 77.8–89.9 %, AUC 0.791–0.903).

Conclusions

DL-based automated AVC quantification may be comparable with manual measurements. The diagnostic performance of the DL-measured AVC volume and Agatston score for classification of severe AVC outperforms radiologist readers.

Journal: European Journal of Radiology

Author

Suyon Chang, Hwiyoung Kim, Young Joo Suh, Dong Min Choi, Hyunghu Kim, Dong Kyu Kim, Jin Young Kim, Jin Young Yoo, and Byoung Wook Choi

DOI: doi.org/10.1016/j.ejrad.2021.109582

Abstract

Rationale and Objectives

Accurate differential diagnosis is essential because cardiac tumors and thrombi have different prognoses and therapeutic approaches. Native T1 map provides an objective T1 time quantifications of cardiac mass without the need for a contrast agent. We examined the diagnostic performance of radiomics features for differentiating cardiac tumors from thrombi using cardiac magnetic resonance imaging T1 mapping technique compared to that of late gadolinium enhancement (LGE) imaging.

Materials and Methods

This retrospective study included 22 cardiac tumors and 21 thrombi of 41 patients who underwent cardiac magnetic resonance imaging from December 2013 to May 2018. Fifty-six radiomics features were extracted from native T1 images. The least absolute shrinkage and selection operator method was used for feature selection and rad score extraction. The diagnostic performance of the rad score was compared to that of the native T1 value (mean T1) and LGE ratio.

Results

The area under the receiver operating characteristic curve of the rad score was higher than that of the mean T1 and LGE ratio (0.98 vs. 0.86 vs. 0.82, p = 0.001). With the optimal cut-off value, the rad score showed sensitivity, specificity, and accuracy of 95.4%, 95.2%, and 95.2%, respectively. Combination of the rad score and mean T1 showed a significantly higher diagnostic performance than mean T1 (p = 0.019) or LGE ratio (p = 0.022).

Conclusion

The rad score derived from native T1 maps can differentiate thrombi from tumors better than the mean T1 or LGE ratio. This is valuable for determining a treatment strategy for cardiac lesions in patients who cannot tolerate contrast agents.

Journal: Academic Radiology

Author

Jinwoo Son, Yoo Jin Hong, Sujeong Kim, Kyunghwa Han, Hye-Jeong Lee, Jin Hur, Young Jin Kim, and Byoung Wook Choi

DOI: doi.org/10.1016/j.acra.2020.12.009

Abstract 

Machine learning offers great opportunities to streamline and improve clinical care from the perspective of cardiac imagers, patients, and the industry and is a very active scientific research field. In light of these advances, the European Society of Cardiovascular Radiology (ESCR), a non-profit medical society dedicated to advancing cardiovascular radiology, has assembled a position statement regarding the use of machine learning (ML) in cardiovascular imaging. The purpose of this statement is to provide guidance on requirements for successful development and implementation of ML applications in cardiovascular imaging. In particular, recommendations on how to adequately design ML studies and how to report and interpret their results are provided. Finally, we identify opportunities and challenges ahead. While the focus of this position statement is ML development in cardiovascular imaging, most considerations are relevant to ML in radiology in general.

Key Points

• Development and clinical implementation of machine learning in cardiovascular imaging is a multidisciplinary pursuit.

• Based on existing study quality standard frameworks such as SPIRIT and STARD, we propose a list of quality criteria for ML studies in radiology.

• The cardiovascular imaging research community should strive for the compilation of multicenter datasets for the development, evaluation, and benchmarking of ML algorithms.

Journal: European Radiology

Author

Thomas Weikert, Marco Francone, Suhny Abbara, Bettina Baessler, Byoung Wook Choi, Matthias Gutberlet, Elizabeth M. Hecht, Christian Loewe, Elie Mousseaux, Luigi Natale, Konstantin Nikolaou, Karen G. Ordovas, Charles Peebles, Claudia Prieto, Rodrigo Salgado, Birgitta Velthuis, Rozemarijn Vliegenthart, Jens Bremerich, and Tim Leiner 

DOI: doi.org/10.1007/s00330-020-07417-0