Synthetic extracellular volume fraction without hematocrit sampling for hepatic applications

Purpose Calculation of extracellular volume fraction (ECV) currently receives increasing interest as a potential biomarker for non-invasive assessment of liver fibrosis. ECV calculation requires hematocrit (Hct) sampling, which might be difficult to obtain in a high-throughput radiology department. The aim of this study was to generate synthetic ECV for hepatic applications without the need for Hct sampling. Methods In this prospective study participants underwent liver MRI. T1 mapping was performed before and after contrast administration. Blood Hct was obtained prior to MRI. We hypothesized that the relationship between Hct and longitudinal relaxation rate of blood (R1 = 1/T1 blood ) could be calibrated and used to generate the equation for synthetic Htc and ECV calculation. Conventional and synthetic ECV were calculated. Pearson correlation, linear regression and Bland–Altman method were used for statistical analysis. Results 180 consecutive patients were divided into derivation ( n = 90) and validation ( n = 90) cohorts. In the derivation cohort, native R1 blood and Hct showed a linear relationship (Hct MOLLI = 98.04 × (1/T1 blood ) − 33.17, R 2 = 0.75, P