2D fitting improves simultaneous intravoxel incoherent motion (IVIM) and compartmental T2 mapping in the human kidney and liver

Motivation: Pseudo-diffusion volume fraction f estimated by conventional IVIM model is biased due to its TR- and TE-dependence driven by differences in compartmental relaxation times. Goal(s): To estimate TE-independent f values in the kidney and liver at 3T. Approach: Numerical simulations and in vivo experiments were conducted to assess the effect of relaxation times on the IVIM parameter estimates when using the conventional IVIM and extended T2-IVIM models. Results: The IVIM-based f estimates depend on selected TE and TR values. An increase in f with increasing TE was observed in the liver, whereas no clear trend was found in the kidney. Impact: The extended 2D T2-IVIM model efficiently minimizes the bias in f values and allows simultaneous estimation of the IVIM parameter and compartmental T2 values in the liver and kidney.