Validation of T1 mapping techniques: Are phantom studies sufficient?

INTRODUCTION: T1 mapping is critical for most quantitative MRI [1], yet there is a large variation of reported T1 values in vivo, an inconsistency that highlights the issues of reproducibility and accuracy. Literature values of T1 in white matter (WM) at 3T vary from 690ms to 1150ms, a variation much greater than the reported biological range [2-8]. In this work we compare two of the most commonly used T1 mapping methods, Look-Locker (LL) [9, 10] and Variable Flip Angle (VFA) [11, 12], against the gold standard for T1 mapping (Inversion Recovery, IR). While there is reasonable agreement between the different methods in phantoms, such an agreement is not found in vivo.