Quantification of extracellular volume with cardiac computed tomography in patients with left ventricle dysfunction

Abstract

Abstract Background Myocardial fibrosis (MF) is a common endpoint in the majority of pathological mechanisms affecting cardiac muscle, ultimately resulting in cardiac failure. Cardiovascular magnetic resonance (CMR) with gadolinium-based contrast agent and T1 mapping technique is able to deliver a non-invasive quantification of the extracellular volume (ECV) expansion. Recently, ECV estimation with cardiac computed tomography (ECV-CCT) has been validated in the setting of cardiac amyloidosis, showing good agreement with ECV-CMR. However, no evidence is available with last generation single source single energy CT scanner in the clinical context of newly diagnosed left ventricular dysfunction. Therefore, the aim of this study is to test the diagnostic accuracy of ECV-CCT for the detection of MF in patients with recent diagnosis of reduced left ventricle ejection fraction (LVEF), having ECV-CMR as reference technique. Methods A consecutive cohort of 41 patients with newly diagnosed left ventricle dysfunction (LVEF < 50%) was enrolled. Time interval of maximum 30 days was present between CCT and CMR. Myocardial segment evaluability with each technique, agreement between ECV-CMR and ECV-CCT, regression analysis and Bland-Altman analysis were performed. Results Age of enrolled patients was 62 ± 11 years, and mean LVEF at CMR was 35.2 ± 10.7%. Mean total amount of administrated iodinated contrast was 112.6 ± 22.2 ml, while overall radiation exposure for ECV estimation was2.1 ± 1.1 mSv. Out of 656 myocardial segments available, 656 (100%) segments were evaluable at CCT while 640 (97.6%) were evaluable at CMR. ECV-CCT demonstrated slightly lower values compared to ECV-CMR both at global and region-based comparison (all segments, 33.1 ± 8.5% vs 35.5 ± 10.7%, p < 0.001). At regression analysis, strong correlations were described both at global and region-based analysis (all segments, r = 0.877, 95% CI: 0.840 to 0.914). On Bland-Altman analysis, bias between ECV-CMR and ECV-CCT for global analysis was 2.4 (95% CI: -7.8 to 12.7). Conclusions ECV estimation with last-generation single source single energy CT scanner is feasible and accurate. Integration of ECV measurement in comprehensive CCT evaluation of patients with newly diagnosed left ventricular dysfunction can be performed with a small increase in overall radiation exposure.