D-optimal design of b-values for accurate 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 accurate estimation of intra- voxel incoherent motion (IVIM) parameters (f perfusion fraction, Ds slow diffusion, Df fast diffusion) according to the model developed by Le Bihan. Previous studies have addressed the design in a Monte Carlo fash- ion. Due to huge computation times, this approach is feasible only for a limited number of values of the parameters (local design): however, as the parameters of a specific exam are not known a priori, it would be desirable to optimise b-values over a region of parameters. In order to overcome this issue, we propose to use a D-optimal design approach. The optimal combination of b-values can be chosen from a candidate set of predefined values taken from the literature. Our study has two key results: first, 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 can be found very quickly. 
Mario Sansone, Roberta Fusco, Antonella Petrillo
physics.med-ph