Comparison of Stretched Exponential and Non-Negative Least Squares Fitting Methods for Multi-Exponential Diffusion Decay Curves
Friesen Waldner L, Rutt B
Robarts Research Institute
Fitting of multi-exponential decay curves is not trivial. Diffusion decay curves were fit using two different fitting methods: non-negative least squares (NNLS) and a form of the stretched exponential fit. Diffusion decay curves were obtained from twelve tumours in an animal model pre- and post-sacrifice of the animal. Both fitting methods showed significant differences (p<0.05) between the pre- and post-sacrifice decay curves. The sum of the squares of the residuals was higher for the stretched exponential method than the NNLS method both pre- and post-sacrifice suggesting that NNLS provides a better fit to the decay curves in this study.