Sample size calculation for clinical trials using cardiac magnetic resonance partition coefficient and extracellular volume fraction for the assessment of diffuse myocardial fibrosis

Methods A modified Look-Locker with inversion recovery (MOLLI) sequence was used to determine myocardial T1 values pre-, and 12 and 25 min post-administration of a gadolinium-based contrast agent at 3 Tesla. For 24 healthy subjects (8 men; 29±6 years), two separate scans were obtained a) with a bolus of 0.15 mmol/kg of gadopentate dimeglumine and b) 0.1 mmol/kg of gadobenate dimeglumine, respectively, with averaged of 51±34 days between two scans. Separately, 25 heart failure subjects (12 men; 63±14 years), were evaluated after a bolus of 0.15mmol/kg of gadopentate dimeglumine. Myocardial partition coefficient (l) was calculated according to (ΔR1myocardium/ΔR1blood), and ECV was derived from l by adjusting (1-hematocrit).