Three-dimensional T1, T2 and proton density mapping with inversion recovery balanced SSFP

Abstract

By combining a balanced steady-state free precession (bSSFP) readout with an initial inversion pulse, all three contrast parameters, T 1, T 2 and proton density ( M 0), may be rapidly calculated from the signal progression in time. However, here it is shown that this technique is quite sensitive to variation in the applied transmit RF ( B 1) field, leading to pronounced errors in calculated values. Two-dimensional (2D) acquisitions are taxed to accurately quantify the relaxation, as the short RF pulses required by SSFP's rapid TR contain a broad spectrum of excitation angles. A 3D excitation using a large diameter excitation coil was able to correctly quantify the parameters. While the extreme B 1 sensitivity was previously problematic and has precluded use of IR-bSSFP for relaxometry, in this work these obstacles were significantly reduced, allowing the rapid quantification of T 1, T 2 and M 0. The results may further be used to simulate image contrast from common sequences, such as a T 1-weighted or fluid-attenuated inversion recovery (FLAIR) examination.