Quantification of Renal Diffusion-Weighted Images Using a Bi-Exponential Model

Jeff Lei Zhang¹, Eric E. Sigmund¹, Henry Rusinek¹, Hersh Chandarana¹, Qun Chen¹, Pippa Storey¹, Louisa Bokacheva¹, Vivian S. Lee¹

In diffusion weighted imaging of kidney, intravoxel incoherent motion (IVIM) has been shown to contribute substantially to overall signal decay. We hypothesize that IVIM in kidney reflects both renal perfusion and tubular fluid flow. A bi-exponential model was used to analyze volunteer data. Minimal difference was found for pure diffusion coefficient (ADC_D) between cortex and medulla, suggesting that the commonly observed ADC contrast between cortex and medulla is in fact due to IVIM effect. Perfusion faction F_P was estimated as 31%~38%, much higher than 5%~15% observed in perfusion imaging, indicating that the IVIM effect likely contains a significant tubular contribution.