Feasibility of using synthetic myocardial extracellular volume fraction derived from blood CT attenuation for the differentiation of heart failure

Objective: To evaluate the feasibility of using synthetic extracellular volume (ECV) fraction—calculated from synthetic hematocrit (HCT) derived via blood CT attenuation—as an alternative for conventional ECV in differentiation heart failure (HF).Methods: This study prospectively included 120 patients undergoing calcium scoring (CS), coronary CT angiography (CCTA), and late enhancement (LE) imaging (5 minutes after CCTA), with HCT measured within 24 hours. Conventional ECV (ECV-HCT) was calculated using serum HCT. A retrospective cohort of 206 patients with CS and HCT was analyzed to derive synthetic HCT from blood CT attenuation in the left ventricle (LV), right ventricle (RV), and ascending aorta (AO), enabling calculation of synthetic ECV fractions (ECV-LV, ECV-RV, ECV-AO). Results: Among 64 HF and 56 non-HF patients, ECV-HCT was significantly higher in HF cases (36.83 ± 5.75 vs. 30.34 ± 4.88, P