T1 mapping of the myocardium: Intra-individual assessment of the effect of field strength, cardiac cycle and variation by myocardial region (Journal of Cardiovascular Magnetic Resonance)

Purpose: Myocardial T1 relaxation time (T1 time) and extracellular volume fraction (ECV) are altered in the presence of myocardial fibrosis. The purpose of this study was to evaluate acquisition factors that may result in variation of measured T1 time and ECV including magnetic field strength, cardiac phase and myocardial region. Methods: 31 study subjects were enrolled and underwent one cardiovascular MR exam at 1.5T and two exams at 3T, each on separate days. A Modified Look-Locker Inversion Recovery (MOLLI) sequence was acquired before and 5, 10, 12, 20, 25 and 30 min after administration of 0.15mmol/kg gadopentetate dimeglumine (Gd-DTPA; Magnevist) at 1.5T (exam 1). For exam 2, MOLLI sequences were acquired at 3T both during diastole and systole, before and after administration of Gd-DTPA (0.15mmol/kg Magnevist). Exam 3 was identical to exam 2 except gadobenate dimeglumine was administered (Gd-BOPTA; 0.1mmol/kg Multihance). T1 times were measured in myocardium and blood. ECV was calculated by (DeltaR1myocardium /DeltaR1blood)*(1-hematocrit). Results: Before gadolinium, T1 times of myocardium and blood were significantly greater at 3T versus 1.5T (28% and 31% greater, respectively, p