Residual T2 dependent bias of T1 times estimated with the Variable Flip Angle approach at 7T: Evaluation and recommendations.

Imperfect spoiling introduces a bias in T₁ times estimated with the Variable Flip Angle approach. Correction factors accounting for B₁⁺ inhomogeneities have been proposed but a T₂ dependent bias is expected to remain. Here we assess the amplitude of this effect at 7T with a commonly used multi-echo protocol and multiple radiofrequency spoiling increments and gradient spoiler moments. The T₂ dependence is observed in-vivo and varies across spoiling conditions. Given that correction schemes don’t account for T₂ variability, we recommend to use the least sensitive increment, such as 117° or 144°, in association with sufficient spoiling gradient (6π per TR).