Simultaneous T1, T2 and T2*mapping of the liver with multi-shot MI-SAGE

Purpose: To apply multi-shot high-resolution multi inversion spin and gradient echo (MI-SAGE) acquisition for simultaneous liver T1, T2 and T2* mapping. Methods: Inversion prepared spin- and gradient-echo EPI was developed with ascending slice order across measurements for efficient acquisition with T1, T2, and T2* weighting. Multi-shot EPI was also implemented to minimize distortion and blurring while enabling high in-plane resolution. A dictionary-matching approach was used to fit the images to quantitative parameter maps, which were compared to T1 measured by modified LookLocker (MOLLI), T1 measured by variable flip angle (VFA), T2 measured by multiple echo time-based Half Fourier Single-shot Turbo spin-Echo (HASTE), T2 measured by radial turbo-spin-echo (rTSE) and T2* measured by multiple gradient echo (MGRE) sequences. Results: The multi-shot variant of the sequence achieved higher in-plane resolution of 1.7 x 1.7 mm2 with good image quality in 28 s. Derived quantitative maps showed comparable values to conventional mapping methods. As measured in phantom and in vivo, MOLLI, MESE and MGRE give closest values to MISAGE. VFA, HASTE and rTSE show obvious overestimation. Conclusions: The proposed multi-shot inversion prepared spin- and gradient-echo EPI sequence allows for highresolution quantitative T1, T2 and T2 liver tissue characterization in a single breath-hold scan.