Performance bounds analysis in multichannel diffusion-MRI

In this paper, we develop Cramèr-Rao Bound (CRB) expressions in multichannel diffusion MRI. We consider a multi-tensor model with a Non-central Chi (Nc-Chi) distributed noise. The CRB formulas involve integral expressions that are numerically evaluated. In a second step, we propose to simplify the CRB calculation by introducing two analytical approximate expressions for high SNR and low SNR, respectively. Moreover, we develop CRB formulas for the parameters of clinical interest such as the Fractional Anisotropy (FA) and the principal tensor directions. Finally, we exploit these CRBs to analyze the impact of controllable system parameters (e.g. b-value, number of gradient diffusion, number of acquisition coils, etc.) on the clinical parameter estimation in view of future optimal design of the acquisition protocol.