A proof of concept for tissue characterization in atypical autosomal dominant polycystic kidney disease patients from diffusion tensor imaging

Background The potential of magnetic resonance diffusion tensor imaging (MR-DTI) in autosomal dominant polycystic kidney disease (ADPKD) has been poorly investigated. The few studies available are focused on typical ADPKD populations. In this exploratory study we evaluate the value of MR-DTI in atypical ADPKD patients to quantitatively characterize renal tissue, correlating MR-DTI derived parameters with kidney function tests. Methods Ten atypical ADPKD patients have been enrolled in the study. 3D volumes of interest (VOI) corresponding to a “cyst-only VOI” and a “parenchyma-only VOI” for each patient were manually drawn. Several diffusion anisotropy indices were computed, and their values compared between (1) the parenchyma-only VOI and the cyst-only VOI in our population and (2) the corresponding values in healthy kidneys. Results All indexes were able to significantly discriminate between cyst and parenchyma, especially the apparent diffusion coefficient (ADC) (p = 7.3x10-12). Compared to healthy kidneys, in atypical ADPKD patients, parenchymal ADC slightly decreases (2.11 ± 0.0003 vs. 2.15 ± 0.14/2.25 ± 0.1) and parenchymal FA decreases more significantly (0.184 ± 0.098 vs. 0.28 ± 0.05/0.38 ± 0.025). Parenchymal ADC was shown to have the strongest correlation with serum creatinine and estimated glomerular filtration rate (-0.43 and 0.60, respectively). Conclusions MR-DTI has been applied for the first time to ADPKD atypical patients showing its capability of differentiating between cysts and parenchyma. Based on our preliminary findings on a small but rare and poorly studied population, the hypothesis-generated suggests ADC might have the potential to be used as a prognostic index for disease risk stratification.