Diffusion weighted imaging with biexponential analysis of intravoxel incoherent motion in assessment of renal lesions: Preliminary experience

Purpose: Diffusion weighted MRI (DWI) is influenced by perfusion effects at lower b-values, an effect sometimes termed intravoxel incoherent motion (IVIM). Movement of blood in microvasculature can be modeled as pseudo-diffusion and this perfusion effect can be separately determined if both low (<200 sec/mm) and high b values are used. The purpose of our study was to calculate perfusion fraction (fp) and tissue diffusivity (Dt) parameters obtained with multi-b DWI and determine if these parameters can distinguish enhancing from non-enhancing renal lesions using gadolinium-enhanced MRI as the reference standard. Our goals include (1) identifying alternative biomarkers of malignancy to standard methods requiring gadolinium chelates and (2) differentiating between two distinct processes (tissue perfusion and diffusion) that contribute to ADC to determine whether one or both may be used as a more specific marker for malignancy or treatment response.