Improved T1 fitting with the MOLLI sequence

Background T1 mapping has great potential for diagnosing diffuse cardiomyopathies. Modified Look Locker Inversion Recovery (MOLLI) is a promising 2D SSFP technique to measure T1 differences between healthy and diseased states in cardiac tissue. However, this method has been found to provide variable T1 values at different flip angles. Here we develop an improved fitting algorithm which accounts for the imperfect RF flip angle profile and SSFP signal evolution in MOLLI. We show that significantly improved T1 accuracy can be achieved across a larger range of flip angle in human calf muscle. This algorithm is then applied to MOLLI data obtained in the heart using an optimized flip angle.