High‐resolution T1 mapping of the brain at 3T with driven equilibrium single pulse observation of T1 with high‐speed incorporation of RF field inhomogeneities (DESPOT1‐HIFI)

Abstract

Purpose: To investigate an alternative approach to correct for flip angle inaccuracies in the driven equilibrium single pulse observation of T1 (DESPOT1) T1 mapping method. Materials and Methods: While DESPOT1 is a robust method for rapid whole‐brain voxelwise mapping of the longitudinal relaxation time, the approach is inherently sensitive to inaccuracies in the transmitted flip angle, defined by the B1 field, which become more severe with increased field. Here we propose an extension of the DESPOT1 technique, involving the additional acquisition of an inversion‐prepared SPGR image alongside the conventional multiangle DESPOT1 data. From these combined data both B1 and T1 may be determined with high accuracy and precision. The method is evaluated at 3T with phantom and in vivo imaging experiments, with derived T1 estimates compared with values calculated from multiple inversion time inversion recovery data. Results: The method provides robust correction of flip angle variations, with less than 5% error compared with reference values for T1 between 300 msec and 2500 msec. Conclusions: The described approach, dubbed DESPOT1‐HIFI, permits whole‐brain T1 mapping at 3T, with 1 mm 3 isotropic voxels, in a clinically feasible time (≈10 minutes) with T1 accuracy greater than 5% and with high precision. J. Magn. Reson. Imaging 2007;26:1106–1111. © 2007 Wiley‐Liss, Inc.