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Objectives: To investigate the value of body composition indices derived from pre-procedural computed tomography (CT) in predicting 1-year mortality among patients who underwent transcatheter aortic valve replacement (TAVR)., Materials and Methods: We assessed consecutive patients who underwent TAVR between June 2016 and December 2021 at a single academic medical center. Skeletal muscle and subcutaneous fat area at the T4, T12, and L3 levels on pre-procedural CT were measured. The association between body composition and 1-year mortality was evaluated using Cox proportional hazard regression analysis., Results: Finally, 408 patients were included (185 men and 223 women; mean age, 81.7 ± 5.1 years; range, 62-98 years). Post-procedural death occurred in 13.2% of patients. The muscle-height index and fat-height index at the L3 level were more strongly correlated with those at the T12 level (r = 0.765, p < 0.001 and r = 0.932, p < 0.001, respectively) than with those at the T4 level (r = 0.535, p < 0.001 and r = 0.895, p < 0.001, respectively). The cumulative 1-year mortality rate was highest for patients with both sarcopenia and adipopenia (26%), followed by those with adipopenia only (17%), those with sarcopenia only (12%), and those with neither sarcopenia nor adipopenia (8%, p = 0.002). Multivariable analysis revealed that body composition at the T12 level was an independent risk factor for 1-year mortality (hazard ratio: 4.09, 95% confidence interval: 2.01-8.35) in patients with both sarcopenia and adipopenia (p < 0.001)., Conclusion: Sarcopenia or adipopenia assessed with CT at the thoracic level may be valuable for stratifying 1-year all-cause mortality in patients who undergo TAVR., Clinical Relevance Statement: Skeletal muscle and subcutaneous fat mass indices at the level of T12, measured on pre-procedural CT, have value for risk stratification of 1-year all-cause mortality in patients who undergo transcatheter aortic valve replacement., Key Points: Sarcopenia and adipopenia are associated with the prognosis of patients undergoing transcatheter aortic valve replacement. Body composition at the T12 level was an independent risk factor for 1-year all-cause mortality. Sarcopenia or adipopenia assessed at T12 with pre-procedural CT is valuable for risk stratification., Competing Interests: Compliance with ethical standards. Guarantor: The scientific guarantor of this publication is Y.J.K. Conflict of interest: The authors of this manuscript declare no relationships with any companies, whose products or services may be related to the subject matter of the article. Statistics and biometry: One of the authors (Mr. Yun Ho Roh) has significant statistical expertise. Informed consent: Written informed consent was waived by the Institutional Review Board. Ethical approval: Institutional Review Board approval was obtained. Study subjects or cohorts overlap: No study subjects have been previously reported. Methodology: Diagnostic or prognostic study Performed at one institution, (© 2024. The Author(s), under exclusive licence to European Society of Radiology.)

Objectives: To assess the feasibility of the UTE-MRI radiomic model in predicting the micropapillary and/or solid (MP/S) patterns of surgically resected lung adenocarcinoma., Materials and Methods: We prospectively enrolled 74 lesions from 71 patients who underwent UTE-MRI and CT before curative surgery for early lung adenocarcinoma. For conventional radiologic analysis, we analyzed the longest lesion diameter and lesion characteristics at both UTE-MRI and CT. Radiomic features were extracted from the volume of interest of the lesions and Rad-scores were generated using the least absolute shrinkage and selection operator with fivefold cross-validation. Six models were constructed by combining the conventional radiologic model, UTE-MRI Rad-score, and CT Rad-score. The areas under the curves (AUCs) of each model were compared using the DeLong method. Early recurrence after curative surgery was analyzed, and Kaplan-Meier survival analysis was performed., Results: Twenty-four lesions were MP/S-positive, and 50 were MP/S-negative. The longitudinal size showed a small systematic difference between UTE-MRI and CT, with fair intermodality agreement of lesion characteristic (kappa = 0.535). The Rad-scores of the UTE-MRI and CT demonstrated AUCs of 0.84 and 0.841, respectively (p = 0.98). Among the six models, mixed conventional, UTE-MRI, and CT Rad-score model showed the highest diagnostic performance (AUC = 0.879). In the survival analysis, the high- and low-risk groups were successfully divided by the Rad-score in UTE-MRI (p = 0.01) and CT (p < 0.01)., Conclusion: UTE-MRI radiomic model predicting MP/S positivity is feasible compared with the CT radiomic model. Also, it was associated with early recurrence in the survival analysis., Clinical Relevance Statement: A radiomic model utilizing UTE-MRI, which does not present a radiation hazard, was able to successfully predict the histopathologic subtype of lung adenocarcinoma, and it was associated with the patient's recurrence-free survival., Key Points: • No studies have reported the ultrashort echo time (UTE)-MRI-based radiomic model for lung adenocarcinoma. • The UTE-MRI Rad-score showed comparable diagnostic performance with CT Rad-score for predicting micropapillary and/or solid histopathologic pattern. • UTE-MRI is feasible not only for conventional radiologic analysis, but also for radiomics analysis., (© 2023. The Author(s), under exclusive licence to European Society of Radiology.)

Objectives: To evaluate commercial deep learning-based software for fully automated coronary artery calcium (CAC) scoring on non-electrocardiogram (ECG)-gated low-dose CT (LDCT) with different slice thicknesses compared with manual ECG-gated calcium-scoring CT (CSCT)., Methods: This retrospective study included 567 patients who underwent both LDCT and CSCT. All LDCT images were reconstructed with a 2.5-mm slice thickness (LDCT 2.5-mm ), and 453 LDCT scans were reconstructed with a 1.0-mm slice thickness (LDCT 1.0-mm ). Automated CAC scoring was performed on CSCT (CSCT auto ), LDCT 1.0-mm , and LDCT 2.5-mm images. The reliability of CSCT auto , LDCT 1.0-mm , and LDCT 2.5-mm was compared with manual CSCT scoring (CSCT manual ) using intraclass correlation coefficients (ICCs) and Bland-Altman analysis. Agreement, in CAC severity category, was analyzed using weighted kappa statistics. Diagnostic performance at various Agatston score cutoffs was also calculated., Results: CSCT auto , LDCT 1.0-mm , and LDCT 2.5-mm demonstrated excellent agreement with CSCT manual (ICC [95% confidence interval, CI]: 1.000 [1.000, 1.000], 0.937 [0.917, 0.952], and 0.955 [0.946, 0.963], respectively). The mean difference with 95% limits of agreement was lower with LDCT 1.0-mm than with LDCT 2.5-mm (19.94 [95% CI, -244.0, 283.9] vs. 45.26 [-248.2, 338.7]). Regarding CAC severity, LDCT 1.0-mm achieved almost perfect agreement, and LDCT 2.5-mm achieved substantial agreement (kappa [95% CI]: 0.809 [0.776, 0.838], 0.776 [0.740, 0.809], respectively). Diagnostic performance for detecting Agatston score ≥ 400 was also higher with LDCT 1.0-mm than with LDCT 2.5-mm (F1 score, 0.929 vs. 0.855)., Conclusions: Fully automated CAC-scoring software with both CSCT and LDCT yielded excellent reliability and agreement with CSCT manual . LDCT 1.0-mm yielded more accurate Agatston scoring than LDCT 2.5-mm using fully automated commercial software., Key Points: • Total Agatston scores and all vessels of CSCT auto , LDCT 1.0-mm , and LDCT 2.5-mm demonstrated excellent agreement with CSCT manual (all ICC > 0.85). • The diagnostic performance for detecting all Agatston score cutoffs was better with LDCT 1.0-mm than with LDCT 2.5-mm . • This automated software yielded a lower degree of underestimation compared with methods described in previous studies, and the degree of underestimation was lower with LDCT 1.0-mm than with LDCT 2.5-mm ., (© 2022. The Author(s), under exclusive licence to European Society of Radiology.)

Objectives: To validate an artificial intelligence (AI)-based fully automatic coronary artery calcium (CAC) scoring system on non-electrocardiogram (ECG)-gated low-dose chest computed tomography (LDCT) using multi-institutional datasets with manual CAC scoring as the reference standard., Methods: This retrospective study included 452 subjects from three academic institutions, who underwent both ECG-gated calcium scoring computed tomography (CSCT) and LDCT scans. For all CSCT and LDCT scans, automatic CAC scoring (CAC&#95;auto) was performed using AI-based software, and manual CAC scoring (CAC&#95;man) was set as the reference standard. The reliability and agreement of CAC&#95;auto was evaluated and compared with that of CAC&#95;man using intraclass correlation coefficients (ICCs) and Bland-Altman plots. The reliability between CAC&#95;auto and CAC&#95;man for CAC severity categories was analyzed using weighted kappa (κ) statistics., Results: CAC&#95;auto on CSCT and LDCT yielded a high ICC (0.998, 95% confidence interval (CI) 0.998-0.999 and 0.989, 95% CI 0.987-0.991, respectively) and a mean difference with 95% limits of agreement of 1.3 ± 37.1 and 0.8 ± 75.7, respectively. CAC&#95;auto achieved excellent reliability for CAC severity (κ = 0.918-0.972) on CSCT and good to excellent but heterogenous reliability among datasets (κ = 0.748-0.924) on LDCT., Conclusions: The application of an AI-based automatic CAC scoring software to LDCT shows good to excellent reliability in CAC score and CAC severity categorization in multi-institutional datasets; however, the reliability varies among institutions., Key Points: • AI-based automatic CAC scoring on LDCT shows excellent reliability with manual CAC scoring in multi-institutional datasets. • The reliability for CAC score-based severity categorization varies among datasets. • Automatic scoring for LDCT shows a higher false-positive rate than automatic scoring for CSCT, and most common causes of a false-positive are image noise and artifacts for both CSCT and LDCT., (© 2022. The Author(s), under exclusive licence to European Society of Radiology.)

Objectives: To investigate the effect of the phantom-based correction method for standardizing myocardial native T1 and extracellular volume fraction (ECV) in healthy subjects., Methods: Seventy-one healthy asymptomatic adult (≥ 20 years) volunteers of five different age groups (34 men and 37 women, 45.5 ± 15.5 years) were prospectively enrolled in three academic hospitals. Cardiac MRI including Modified Look - Locker Inversion recovery T1 mapping sequence was performed using a 3-Tesla system with a different type of scanner for each hospital. Native T1 and ECV were measured in the short-axis T1 map and analyzed for mean values of the 16 entire segments. The myocardial T1 value of each subject was corrected based on the site-specific equation derived from the T1 Mapping and ECV Standardization phantom. The global native T1 and ECV were compared between institutions before and after phantom-based correction, and the variation in native T1 and ECV among institutions was assessed using a coefficient of variation (CoV)., Results: The global native T1 value significantly differed between the institutions (1198.7 ± 32.1 ms, institution A; 1217.7 ± 39.9 ms, institution B; 1232.7 ± 31.1 ms, institution C; p = 0.002), but the mean ECV did not (26.6-27.5%, p = 0.355). After phantom-based correction, the global native T1 and ECV were 1289.7 ± 32.4 ms and 25.0 ± 2.7%, respectively, and CoV for native T1 between the three institutions decreased from 3.0 to 2.5%. The corrected native T1 value did not significantly differ between institutions (1284.5 ± 31.5 ms, institution A; 1296.5 ± 39.1 ms, institution B; 1291.3 ± 29.3 ms, institution C; p = 0.440), and neither did the ECV (24.4-25.9%, p = 0.078)., Conclusions: The phantom-based correction method can provide standardized reference T1 values in healthy subjects., Key Points: • After phantom-based correction, the global native T1 of 16 entire myocardial segments on 3-T cardiac MRI is 1289.4 ± 32.4 ms, and the extracellular volume fraction was 25.0 ± 2.7% for healthy subjects. • After phantom - based correction was applied, the differences in the global native T1 among institutions became insignificant, and the CoV also decreased from 3.0 to 2.5%., (© 2022. The Author(s).)

Objectives: To evaluate the quality of radiomics studies using cardiac magnetic resonance imaging (CMR) according to the radiomics quality score (RQS), Transparent Reporting of a multivariable prediction model for Individual Prognosis Or Diagnosis (TRIPOD) guidelines, and the standards defined by the Image Biomarker Standardization Initiative (IBSI) and identify areas needing improvement., Materials and Methods: PubMed and Embase were searched to identify radiomics studies using CMR until March 10, 2021. Of the 259 identified articles, 32 relevant original research articles were included. Studies were scored according to the RQS, TRIPOD guidelines, and IBSI standards by two cardiac radiologists., Results: The mean RQS was 14.3% of the maximum (5.16 out of 36). RQS were low for the demonstration of validation (-60.6%), calibration statistics (1.6%), potential clinical utility (3.1%), and open science (3.1%) items. No study conducted a phantom study or cost-effectiveness analysis. The adherence to TRIPOD guidelines was 55.9%. Studies were deficient in reporting title (3.1%), stating objective in abstract and introduction (6.3% and 9.4%), missing data (0%), discrimination/calibration (3.1%), and how to use the prediction model (3.1%). According to the IBSI standards, non-uniformity correction, image interpolation, grey-level discretization, and signal intensity normalization were performed in two (6.3%), four (12.5%), six (18.8%), and twelve (37.5%) studies, respectively., Conclusion: The quality of radiomics studies using CMR is suboptimal. Improvements are needed in the areas of validation, calibration, clinical utility, and open science. Complete reporting of study objectives, missing data, discrimination/calibration, how to use the prediction model, and preprocessing steps are necessary., Key Points: • The quality of science in radiomics studies using CMR is currently inadequate. • RQS were low for validation, calibration, clinical utility, and open science; no study conducted a phantom study or cost-effectiveness analysis. • In stating the study objective, missing data, discrimination/calibration, how to use the prediction model, and preprocessing steps, improvements are needed., (© 2022. The Author(s), under exclusive licence to European Society of Radiology.)

Objectives: To assess the quality of current radiomics research on cardiac CT using radiomics quality score (RQS) and Transparent Reporting of a multivariable prediction model for Individual Prognosis Or Diagnosis (TRIPOD) systems., Methods: Systematic searches of PubMed and EMBASE were performed to identify all potentially relevant original research articles about cardiac CT radiomics. Fifteen original research articles were selected. Two cardiac radiologists assessed the quality of the methodology adopted in those studies according to the RQS and TRIPOD guidelines. Basic adherence rates for the following six key domains were evaluated: image protocol and reproducibility, feature reduction and validation, biologic/clinical utility, performance index, high level of evidence, and open science., Results: Among the 15 included articles, six (40%) were about coronary artery disease and six (40%) were about myocardial infarction. The mean RQS was 9.9 ± 7.3 (27.4% of the ideal score of 36), and the basic adherence rate was 44.6%. Fourteen (93.3%) and nine (60%) studies performed feature selection and validation, but only two (13.3%) of them performed external validation. Two studies (13.3%) were prospective, and only one study (6.7%) conducted calibration analysis and stated the potential clinical utility. None of the studies conducted phantom study and cost-effective analysis. The overall adherence rate for TRIPOD was 63%., Conclusion: The quality of radiomics studies in cardiac CT is currently insufficient. A higher level of evidence is required, and analysis of clinical utility and calibration of model performance need to be improved., Key Points: • The quality of science of radiomics studies in cardiac CT is currently insufficient. • No study conducted a phantom study or cost-effective analysis, with further limitations being demonstrated in a high level of evidence for radiomics studies. • Analysis of clinical utility and calibration of model performance need to be improved, and a higher level of evidence is required., (© 2021. The Author(s), under exclusive licence to European Society of Radiology.)

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., (© 2021. European Society of Radiology.)

Objectives: To determine whether quantitative radiomic features from cardiac CT could differentiate the left atrial appendage (LAA) thrombus from circulatory stasis in patients with valvular heart disease., Methods: Ninety-five consecutive patients with valvular heart disease and filling defects in LAA on two-phase cardiac CT from March 2016 to August 2018 were retrospectively enrolled and classified as having thrombus or stasis by transesophageal echocardiography or cardiac surgery. The ratio of Hounsfield units in the filling defects to those in the ascending aorta (AA) was calculated on early- and late-phase CT (LAA/AA E and LAA/AA L , respectively). Radiomic features were extracted from semi-automated three-dimensional segmentation of the filling defect on early-phase CT. The diagnostic ability of radiomic features for differentiating thrombus from stasis was assessed and compared to LAA/AA E and LAA/AA L by comparing the AUC of ROC curves. Diagnostic performances of CT attenuation ratios and radiomic features were validated with an independent validation set., Results: Thrombus was diagnosed in 25 cases and stasis in 70. Sixty-eight radiomic features were extracted. Values of 8 wavelet-transformed features were lower in thrombus than in stasis (p < 0.001). The AUC value of a radiomic feature, wavelet&#95;LHL, for diagnosing thrombus was 0.78, which was higher than that of LAA/AA E (AUC = 0.54, p = 0.025) and similar to that of LAA/AA L (AUC = 0.76, p = 0.773). In the validation set, the AUC of wavelet&#95;LHL was 0.71, which was higher than that of LAA/AA E (AUC = 0.57, p = 0.391) and similar to that of LAA/AA L (AUC = 0.75, p = 0.707)., Conclusions: Quantitative radiomic features from the early phase of cardiac CT may help diagnose LAA thrombus in patients with valvular heart disease., Key Points: • Wavelet-transformed grey-level non-uniformity values from radiomic analysis are significantly lower for LAA thrombus than for circulatory stasis. • Radiomic features may have an additional value for differentiating LAA thrombus from circulatory stasis when interpreting single-phase cardiac CT. • Radiomic features extracted from single-phase images may show similar diagnostic ability as conventional quantitative analysis from two-phase images.

Objectives: To identify the optimal method for evaluation of coronary artery calcium (CAC) severity on non-electrocardiogram-gated low-dose chest computed tomography (LDCT) in a nationwide lung cancer screening registry., Methods: A total of 256 subjects were retrospectively enrolled from participants of the Korean Lung Cancer Screening (K-LUCAS) project (an LDCT lung cancer screening registry for high-risk individuals). Four board-certified cardiothoracic radiologists independently assessed CAC severity using four different scoring methods (visual assessment, artery-based grading, segment-involvement grading, and segment-based grading) and classified severity for each case using all four methods as none, mild, moderate, or severe. Agreements between the four observers for CAC category classification and between the four different scoring methods for the same observer were assessed by Fleiss kappa statistics. Evaluation time for CAC grading was compared between observers and between grading methods., Results: Interobserver agreement was moderate for visual assessment (Fleiss kappa 0.451) and substantial for the other three methods (Fleiss kappa 0.673-0.704). Agreement between the four grading methods for the same observer was substantial for three observers (Fleiss kappa 0.610-0.705) and moderate for one (Fleiss kappa 0.578). Mean evaluation time differed significantly between methods (visual assessment, 14.3 ± 11.8 s; artery-based grading, 17.6 ± 22.3 s, segment-involvement grading, 19.2 ± 6.8 s; segment-based grading, 34.2 ± 37.4 s; p < 0.01)., Conclusion: Artery-based grading could be appropriate with substantial interobserver agreement and an acceptable mean evaluation time., Key Points: • CAC severity grading methods on LDCT show moderate to substantial agreements between grading methods and observers. • Artery-based grading could be appropriate with substantial interobserver agreement and a mean evaluation time of 17.6 s. • Visual assessment is disadvantaged by high interobserver variability despite having the shortest evaluation time.

Objective: To investigate the incidence of thoracic recurrence and the diagnostic value of chest CT for postoperative surveillance in curatively-resected colorectal cancer (CRC) patients., Methods: This retrospective study consisted of 648 CRC patients (M:F, 393:255; mean age, 66.2 years) treated with curative surgery between January 2010 and December 2012. The presence of CRC recurrence over follow-ups was analysed and recurrence-free survival and risk factors of recurrence were assessed using Kaplan-Meier analysis with log-rank test and Cox-regression analysis, respectively., Results: Over a median follow-up of 57 months, thoracic recurrence occurred in 8.0% (52/648) of patients with a median recurrence-free survival rate of 19.5 months. Among the 52 patients with thoracic recurrence, 18 (2.7%) had isolated thoracic recurrence, and only five (0.8%) were diagnosed through chest CT. Risk factors of overall thoracic recurrence included age, positive resection margin, presence of venous invasion, positive pathologic N-class, and presence of abdominal recurrence (odds ratio [OR] = 1.78, 19.691, 2.993, 2.502, and 31.137; p = 0.045, 0.004, 0.001, 0.005, and p < 0.001, respectively). As for isolated thoracic recurrence, serum carcinoembryonic antigen level ≥ 5 ng/mL during postoperative follow-up (OR = 9.112; p < 0.001) was demonstrated to be the only predictive factor. There were no thoracic recurrences in patients with CRC stages 0 and I., Conclusion: In patients with curatively-resected CRCs, routine surveillance using chest CT may be of limited value, particularly in those with CRC stages 0 or I, as recurrence only detectable through chest CT was shown to be rare., Key Points: • Postoperative thoracic recurrence only detectable through chest CT was shown to be rare. • There were no thoracic recurrences in colorectal cancers stage 0 and I. • Postoperative surveillance chest CT is of limited value in patients with curatively resected colorectal cancers.

Objectives: The aim was to investigate the effect of clinico-radiologic variables, including total tumor (T total ) size and clinical T category, on the prognosis of patients with stage IA (T1N0M0) lung adenocarcinomas appearing as part-solid nodules (PSNs)., Methods: This institutional review board-approved retrospective study included 506 patients (male:female = 200:306; median age, 62 years) with PSNs of the adenocarcinoma spectrum in clinical stage IA who underwent standard lobectomy at a single tertiary medical center. Prognostic stratification of the patients in terms of disease-free survival was analyzed with variables including age, sex, T total size, solid portion size, clinical T category, and tumor location using univariate and subsequent multivariate Cox regression analysis. Subgroup analysis was performed to reveal the effect of the T total size at each clinical T category., Results: Multivariate Cox regression analysis demonstrated that T total size*cT1b [interaction term; hazard ratio (HR) = 1.091; 95% confidence interval (CI): 1.015, 1.173; p = 0.019] and cT1c (HR = 68.436; 95% CI: 2.797, 1674.415; p = 0.010) were independent risk factors for the tumor recurrence. When patients with cT1b were dichotomized based on a T total size cutoff of 3.0 cm, PSNs with T total > 3.0 cm showed a significantly worse outcome (HR = 3.796; 95% CI: 1.006, 14.317; p = 0.049). No significant difference was observed in the probability of recurrence between cT1b with T total > 3.0 cm and cT1c (p = 0.915)., Conclusions: T total size is a significant prognostic factor in adenocarcinoma patients in cT1b without lymph node or distant metastasis. PSNs in cT1b with T total > 3.0 cm have a comparable risk of lung cancer recurrence to those in cT1c., Key Points: • Current T descriptor was a powerful prognostic factor in stage IA adenocarcinomas appearing as part-solid nodules. • Total tumor size further stratified risk of recurrence of adenocarcinomas in cT1b. • Upstaging of tumors in cT1b with total tumor size > 3.0 cm may be more appropriate.

Objectives: We aimed to evaluate the prognostic role of cardiac magnetic resonance imaging (CMR)-based extracellular volume fraction (ECV) in patients with non-ischemic dilated cardiomyopathy (NIDCM) and compare it with late gadolinium enhancement (LGE) parameters., Methods: This was a single-center, prospective, cohort study of 117 NIDCM patients (71 men, 51.9 ± 16.7 years) who underwent clinical 3.0-T CMR. Myocardial ECV and LGE were quantified on the left ventricular myocardium. The presence of midwall LGE was also detected. Nineteen healthy subjects served as controls. The primary end points were cardiovascular (CV) events defined by CV death, rehospitalization due to heart failure, and heart transplantation., Results: During the follow-up period (median duration, 11.2 months; 25 th -75 th percentile, 7.8-21.9 months), the primary end points occurred in 19 patients (16.2%). The ECV (per 3% and 1% increase) was associated with a hazard ratio of 1.80 and 1.22 (95% confidence interval [CI], 1.48-2.20 and 1.14-1.30, respectively; p < 0.001) for the CV events. Multivariable analysis also indicated that ECV was an independent prognostic factor and had a higher prognostic value (Harrell's c statistic, 0.88) than LGE quantification values (0.77) or midwall LGE (0.80)., Conclusion: CMR-based ECV independently predicts the clinical outcome in NIDCM patients., Key Points: • T1-mapping-based ECV is a useful parameter of risk stratification in NIDCM • ECV has a higher prognostic value than LGE • Contrast-enhanced T1-mapping CMR is a feasible and safe method.

Objectives: To investigate the diagnostic value of dual-energy computed tomography (DECT) in differentiating between low- and high-risk thymomas and thymic carcinomas., Materials: Our institutional review board approved this study, and patients provided informed consent. We prospectively enrolled 37 patients (20 males, mean age: 55.6 years) with thymic epithelial tumour. All patients underwent DECT. For quantitative analysis, two reviewers measured the following tumour parameters: CT attenuation value in contrast Hounsfield units (CHU), iodine-related HU and iodine concentration (mg/ml). Pathological results confirmed the final diagnosis., Results: Of the 37 thymic tumours, 23 (62.2 %) were low-risk thymomas, five (13.5 %) were high-risk thymomas and nine (24.3 %) were thymic carcinomas. According to quantitative analysis, iodine-related HU and iodine concentration were significantly different among low-risk thymomas, high-risk thymomas and thymic carcinomas (median: 29.78 HU vs. 14.55 HU vs. 19.95 HU, p = 0.001 and 1.92 mg/ml vs. 0.99 mg/ml vs. 1.18 mg/ml, p < 0.001, respectively)., Conclusion: DECT using a quantitative analytical method based on iodine concentration measurement can be used to differentiate among thymic epithelial tumours using single-phase scanning., Key Points: • IHU and IC were lower in high-risk thymomas/carcinomas than in low-risk thymomas • IHU and IC were lower in advanced-stage thymomas than in early-stage thymomas • Dual-energy CT helps differentiate among thymic epithelial tumours.

Objectives: The purpose of this study was to determine whether dual-energy computed tomography (DECT) angiography could differentiate pulmonary thromboembolism (PTE) from pulmonary artery sarcoma (PAS)., Methods: We prospectively enrolled 19 patients that had a filling defect in the main pulmonary artery on DECT. Six patients who had PAS and underwent DECT were retrospectively enrolled for comparison. Pathological results or follow-up CT after anticoagulation therapy were used to make the final diagnosis. Two investigators measured the following parameters at the filling defect in the main pulmonary artery: CT attenuation density [Hounsfield units (HU)], iodine-related HU (IHU) and iodine concentration (IC, mg/ml)., Results: From a total of 25 patients (M:F = 10:15; mean age, 65 years old), 19 were categorised into the PTE group and six were categorised into the PAS group. The mean HU values were not significantly different between the PTE and PAS groups (45.5 ± 15.9 vs 47.1 ± 9.2 HU; P = 0.776). However, the mean IHU and IC values of the lesions were significantly different between the PTE and PAS groups (10.6 ± 7.2 vs 27.9 ± 9.1 HU; P = 0.004, and 0.61 ± 0.39 vs 1.49 ± 0.57; P = 0.001)., Conclusions: DECT angiography using a quantitative analytic methodology can be used to differentiate PTE and PAS., Key Points: • DECT can be useful for differentiation of PAS and PTE. • With quantitative analysis, DECT offers tissue characterisation by detecting lesion parameter increases. • The patients without predisposing factors for PTE can be candidates for DECT.