Navigator-gated 2D radial MR fingerprinting of the kidney at 3T.

Motivation: A free-breathing renal joint T1-T2 MR fingerprinting technique with respiratory navigators would allow kidney function to be mapped non-invasively in patients that cannot hold their breath. Goal(s): To assess the effect of rejected respiratory navigators on the relaxation times and their precision. Approach: Joint kidney T1-T2 maps with four different navigator acceptance window widths (NAWW, from ±4mm to ±32mm) were acquired in 8 healthy volunteers and compared to clinical routine maps. Results: Map accuracy and precision were high and did not change as a function of NAWW, suggesting that the NAWW can be chosen as a balance between navigator inefficiency and through-plane motion. Impact: This work demonstrates the feasibility of a free-breathing 2D joint T1-T2 renal MR fingerprinting in healthy volunteers. The navigator allows a free breathing acquisition with limited through-plane motion.