In Vivo Brain Sodium T2* Mapping with a Multiple-Echo Flexible TPI Sequence

Aiming Lu¹, Ian C. Atkinson¹, Keith R. Thulborn¹

The sodium MR signal is affected by the local electrical field gradient and exhibits bi-exponential relaxation behavior in brain. The relaxation times not only are critical parameters for optimizing the sequences for quantifying tissue sodium concentration, but also convey information on the local sodium ion environment. However mapping the relaxation times of sodium in biological tissues in vivo is challenging. We demonstrate here with an efficient multiple-echo flexible twisted projection imaging sequence that high quality T2* maps of the sodium MR signal in the entire human brain can be achieved within a reasonable scan time at 3T.