ABSTRACT Purpose To quantitatively assess the bias in the intravoxel incoherent motions (IVIM)–derived pseudo‐diffusion volume fraction ( f ) caused by the differences in relaxation times between the tissue and fluid compartments, and to develop a two‐dimensional ( b ‐value‐TE) fitting approach for simultaneous T2 and IVIM parameter estimation along with an optimal acquisition protocol for the relaxation‐compensated T2‐IVIM imaging in the liver. Methods Simulations were conducted to investigate the TR‐ and TE‐dependent bias in f when using the IVIM model, and to evaluate the applicability of the 2D T2‐IVIM model for reducing this bias. The numerical findings were then validated using the in vivo IVIM data from four healthy volunteers on a 3‐Tesla MRI scanner. Finally, a numerical framework for optimizing the T2‐IVIM protocol for relaxation‐compensated f parameter estimation was proposed and tested using the in vivo data. Results In vivo, the traditional IVIM model showed a trend toward higher f with increasing TE in the liver ( R = 0.46, p = 0.023), but not in the kidney cortex ( R = −0.067, p = 0.76) or medulla ( R = 0.039, p = 0.86). In both simulations and in vivo, 2D T2‐IVIM modeling yielded lower f values and reduced variability in the liver. Our results further suggest that a b ‐TE protocol with six b ‐values and three TEs (50, 60, and 100 ms) may be optimal for liver T2‐IVIM. Conclusion The extended 2D T2‐IVIM model effectively minimizes the TE‐dependent bias in f and allows simultaneous estimation of the IVIM parameter and compartmental T2 values in abdominal organs.
Stabinska et al. (Sun,) studied this question.