TR dependence of phase-cycled bSSFP relaxometry in brain tissue

Abstract

Brain relaxometry with phase-cycled bSSFP shows systematically lower T1 values, if compared to spoiled-GRE or inversion-recovery spin echo methods. One explanation can be the pronounced asymmetry in the bSSFP's frequency profile, observed for tissues. It was recently shown that this asymmetry decreases towards shorter TR, possibly leading to an adjustment of T1 estimates from bSSFP to spoiled-GRE. Here, it was investigated how T1 and T2 quantification is influenced by TR. Contrary to expectation, a stronger mismatch between bSSFP and spoiled-GRE was observed towards shorter TR. The origin of this mismatch can thus not be attributed to the bSSFP profile asymmetry.