Comparison of fitting methods for Non-Gaussian diffusion and IVIM MRI parameter estimation in two mice xenograft models

The optimal fitting method (1-step or 2-step) and b-value threshold (200 or 600 s/mm2) in analyzing IVIM/diffusion data was investigated using two different mice xenograft models (breast and colon cancer). The threshold of b=600 rather than 200s/mm2 was found better in these models, as many cases showed non negligible residual IVIM components left with b=200s/mm2. From simulations, it appears that a too low b value threshold leads to an overestimation of ADC0 and underestimation of K and fIVIM. Those results suggest that the b-value threshold must be checked depending on the tissue types.