Water-Only Look-Locker Inversion recovery (WOLLI) T1 mapping

Purpose Modified Look-Locker Inversion recovery (MOLLI) and Shortened MOLLI (ShMOLLI) T 1 values can deviate substantially from the water T 1 in voxels containing large amounts of water and fat. We introduce Water-Only Look-Locker Inversion recovery (WOLLI) to map water T 1 in tissue containing fat. Theory WOLLI comprises adiabatic water-selective inversion and several balanced steady-state free precession (bSSFP) readouts, followed immediately by adiabatic fat-selective inversion and bSSFP readout(s). Data are fitted pixel-wise and an adapted Deichmann-Haase saturation-correction gives the water T 1 . Methods We compared two WOLLI protocols (WOLLI-w7f1 and WOLLI-w7f2f1), ShMOLLI and single-voxel spectroscopy at 3T in: simulations, fat/water phantoms, and 12 subjects’ livers. Results In simulations with 0-40% fat fraction, T 1 varied by: <0.5% (WOLLI-w7f1), 100% (MOLLI). In phantoms, the accuracy of the methods (i.e. worst-case T 1w difference vs spectroscopy) was: WOLLI-w7f1 (best, maximum difference of 10.2%), WOLLI-w7f2f1 (max. 10.5%), and ShMOLLI (max. 81.5%). In the liver, the root-mean-squared deviations vs spectroscopy were: 374ms (WOLLI-w7f1), 645ms (WOLLI-w7f2f1), and 700ms (ShMOLLI). Conclusion Compared to ShMOLLI, WOLLI is less influenced by fat, but more by B 0 -inhomogeneity. WOLLI was a clear improvement in phantoms but less so in vivo. WOLLI may be suited to scan organs with high fat content such as the liver.