Agreement of left ventricular mass in steady state free precession and delayed enhancement MR images: implications for quantification of fibrosis in congenital and ischemic heart disease

BACKGROUND Left ventricular mass (LVM) is used when expressing infarct or fibrosis as a percentage of the left ventricle (LV). Quantification of LVM is interchangeably carried out in cine steady state free precession (SSFP) and delayed enhancement (DE) magnetic resonance imaging (MRI). However, these techniques may yield different LVM. Therefore, the aim of the study was to compare LVM determined by SSFP and DE MRI in patients and determine the agreement with these sequences with ex vivo data in an experimental animal model. METHODS Ethics committees approved human and animal studies. Informed written consent was obtained from all patients. SSFP and DE images were acquired in 60 patients (20 with infarction, 20 without infarction and 20 pediatric patients). Ex vivo MRI was used as reference method for LVM in 19 pigs and compared to in vivo SSFP and DE. RESULTS LVM was greater in SSFP than in DE (p < 0.001) with a bias of 5.0 +/- 6.7% in humans (r2 = 0.98), and a bias of 7.3 +/- 6.7% (p < 0.001) in pigs (r2 = 0.83). Bias for SSFP and DE images compared to ex vivo LVM was -0.2 +/- 9.0% and -7.7 +/- 8.5% respectively. CONCLUSIONS LVM was higher when measured with SSFP compared to DE. Thus, the percentage infarction of the LV will differ if SSFP or DE is used to determine LVM. There was no significant difference between SSFP and ex vivo LVM suggesting that SSFP is more accurate for LVM quantification. To avoid intrinsic error due to the differences between the sequences, we suggest using DE when expressing infarct as a percentage of LVM.