D-optimal design of b-values for precise intra-voxel incoherent motion imaging

The aim of this paper is to optimally design the set of b-values for diffusion weighted MRI with the aim of precise estimation of intra-voxel incoherent motion (IVIM) parameters (f perfusion fraction, D s slow diffusion, D f fast diffusion) according to the model developed by Le Bihan. Previous studies have addressed the design in a Monte Carlo fashion; however, due to huge computation times, this approach is practical only for a limited number of values of the parameters (local design): however, as the parameters of a specific patient are not known a priori, it would be desirable to optimise b-values over a region of parameters. In order to address this issue, we propose to use a D-optimal design approach. Our study has two key results: first, under fairy general conditions, the optimal design does not depend on perfusion fraction: this allow to perform a search over a 2D parameter space instead of 3D; second, as an exhaustive search over all possible designs would still be time consuming, we proposed an algorithm to find an approximate solution very quickly.