TriExponentialT2Fit[data,EchoTimes]

fits the t2 based on Azzabou N et.al. Validation of a generic approach to muscle water t2 determination at 3T in fat-infiltrated skeletal muscle. J. Magn. Reson. 2015. The fat t2 parameters are automatically estimated from the high signal voxels from the last echo. The output is in units as defined by the EchoTimes, e.g. if EchoTimes is in ms the output is in ms. The output fraction is between 0 an 1. Output is {{S(0), fatFraction, muscleFraction, T2map},callibration} or {S(0), fatFraction, muscleFranction, T2map}.