Rapid High-Resolution T1 Mapping by Variable Flip Angles: Accurate and Precise Measurements in the Presence of RF Field Inhomogeneity
Cheng H, Wright G
The University of Toronto, The Hospital for Sick Children
The variable flip angle (VFA) approach enables rapid 3D T1-mapping with superior precision compared to conventional methods. To ensure accuracy, the influences of B1 inhomogeneity and noise-bias must be considered in addition to the choice of flip angles. We present an accurate and precise approach that accounts for these influences. A simple, parameter-independent T1 correction scheme is derived theoretically for B1-induced error. We identify a noise threshold and show that three properly chosen angles best maintain accuracy and precision across a large T1 range. Improved T1 measurements through the proposed approach are demonstrated in simulations, phantoms, and human brain scans.