A systematic evaluation of three different cardiac T2-mapping sequences at 1.5 and 3T in healthy volunteers

Background: Previous studies showed that myocardial T2 relaxation times measured by cardiac T2mapping vary significantly depending on sequence and field strength. Therefore, a systematic comparison of different T2-mapping sequences and the establishment of dedicated T2 reference values is mandatory for diagnostic decision-making. Methods: Phantom experiments using gel probes with a range of different T1 and T2 times were performed on a clinical 1.5T and 3T scanner. In addition, 30 healthy volunteers were examined at 1.5 and 3T in immediate succession. In each examination, three different T2-mapping sequences were performed at three short-axis slices: Multi Echo Spin Echo (MESE), T2-prepared balanced SSFP (T2prep), and Gradient Spin Echo with and without fat saturation (GraSEFs/GraSE). Segmented T2-Maps were generated according to the AHA 16-segment model and statistical analysis was performed. Results: Significant intra-individual differences between mean T2 times were observed for all sequences. In general, T2prep resulted in lowest and GraSE in highest T2 times. A significant variation with field strength was observed for mean T2 in phantom as well as in vivo, with higher T2 values at 1.5T compared to 3T, regardless of the sequence used. Segmental T2 values for each sequence at 1.5 and 3T are presented. Conclusions: Despite a careful selection of sequence parameters and volunteers, significant variations of the measured T2 values were observed between field strengths, MR sequences and myocardial segments. Therefore, we present segmental T2 values for each sequence at 1.5 and 3T with the inherent potential to serve as reference values for future studies. (C) 2015 Elsevier Ireland Ltd. All rights reserved.