Abstract
To evaluate the feasibility of using synthetic extracellular volume (sECV) fraction-calculated from synthetic hematocrit (sHCT) derived via blood CT attenuation-as an alternative for conventional ECV in differentiation heart failure (HF). This study prospectively included 120 patients undergoing calcium scoring (CS), coronary CT angiography (CCTA), and late enhancement (LE) imaging (5 min after CCTA), with HCT measured within 24 h. Conventional ECV (cECV) was calculated using serum HCT. An additional retrospective cohort of 207 patients with CS and HCT was analyzed. Linear regression was used to derive sHCT from blood CT attenuation in the left ventricle (LV), right ventricle (RV), and ascending aorta (AO), enabling calculation of sHCT fractions (sECV(LV), sECV(RV), sECV(AO)). Among 64 HF and 56 nonHF patients, cECV was significantly higher in HF cases (36.83 ± 5.75 vs. 30.34 ± 4.88, P < 0.001; AUC = 0.82). The sECV(LV), sECV(RV) and sECV(AO) showed strong correlations with cECV (R²=0.96, 0.97, and 0.93). HF patients had higher sECV(LV) (36.79 ± 6.11% vs. 30.42 ± 5.09%, P < 0.001), sECV(RV) (36.49 ± 6.10% vs. 30.19 ± 4.99%, P < 0.001), and sECV(AO) (36.87 ± 6.37% vs. 30.23 ± 5.31%, P < 0.001) than nonHF patients. The AUCs for detecting HF using sECV(LV), sECV(RV) and sECV(AO) were 0.80, 0.79, and 0.80, respectively. Delong test indicated no significant differences among cECV and sECV fractions (all P > 0.05). All ECV fractions showed moderate negative correlations with left ventricular ejection fraction (all P < 0.05). Synthetic ECV fractions derived from cardiac CT are feasible and demonstrate diagnostic performance comparable to conventional ECV fraction in identifying HF.