Model-free Phasor Image Analysis of Quantitative Myocardial T1 Mapping

Abstract Model-free phasor image analysis, well established in fluorescence lifetime imaging and only recently applied to qMRI T2 data processing, is here adapted and validated for myocardial qMRI T1 mapping. Contrarily to routine mono-exponential fitting procedures, phasor enables mapping the lifetime information from all image voxels to a single plot, without resorting to any regression fit analysis, and describing multi-exponential qMRI decays without biases due to violated modelling assumptions. In this study, we test the performance of our recently developed full-harmonics phasor method for unravelling partial-volume effects, motion or pathological tissue alteration, respectively on a numerically-simulated dataset, a healthy subject scan, and two pilot patient datasets. Our results show that phasor analysis can be used, as alternative method to fitting analysis or other model-free approaches, to identify motion artifacts or partial-volume effects at the myocardium-blood interface as characteristic deviations, or delineations of scar and remote myocardial tissue in patient data.