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bioRxiv · 10.1101/2022.01.28.478209

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

Garrison, L. D.·Levick, C.·Pavlides, M.·Marjot, T.·Mozes, F.·Hodson, L.·Neubauer, S.·Robson, M.·Rodgers, C. T.
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Abstract

PurposeModified Look-Locker Inversion recovery (MOLLI) and Shortened MOLLI (ShMOLLI) T1 values can deviate substantially from the water T1 in voxels containing large amounts of water and fat. We introduce Water-Only Look-Locker Inversion recovery (WOLLI) to map water T1 in tissue containing fat. TheoryWOLLI 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 T1. MethodsWe 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. ResultsIn simulations with 0-40% fat fraction, T1 varied by: <0.5% (WOLLI-w7f1), <12% (WOLLI-w7f2f1), and >100% (MOLLI). In phantoms, the accuracy of the methods (i.e. worst-case T1w 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). ConclusionCompared to ShMOLLI, WOLLI is less influenced by fat, but more by B0-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.

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Garrison, L. D., Levick, C., Pavlides, M., Marjot, T., Mozes, F., Hodson, L., Neubauer, S., Robson, M., Rodgers, C. T.. 2022-01-28. Water-Only Look-Locker Inversion recovery (WOLLI) T1 mapping. https://doi.org/10.1101/2022.01.28.478209

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