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The aim of this study was to evaluate the feasibility of using intravoxel incoherent motion (IVIM) imaging for noninvasive assessment of pathologic changes in chronic kidney disease (CKD). Material/Methods: Thirty-four patients with CKD and 20 healthy volunteers were examined on a 1.5 T magnetic resonance imaging (MRI) unit. The examination consisted of morphologic sequences and diffusion-weighted echo-planar sequence with 10 b values. Diffusion parameters were calculated with the use of mono-(apparent diffusion coefficient, ADC) and bi-exponential model: pure diffusion coefficient (D) and perfusion fraction (Fp). Blood samples to assess the serum creatinine level were taken immediately before examination. Ultrasound guided biopsies were performed in less than 30 days from MRI and were scored by an experienced nephropathologist. Parametrical unpaired t-test and ROC curve analysis were used to investigate differences in diffusion parameters in relation to estimated glomerular filtration rate (eGFR). Pearson's correlation coefficients were calculated to assess relationship between diffusion parameters and laboratory and histopathological markers of renal damage. P-value <0.05 indicated statistical significance. Results: Both ADC and D correlated positively with eGFR (respective r 0.74 and 0.72), however D showed a more significant correlation with histopathology: while D correlated negatively with parameters reflecting chronic glomerular (r-0.48) and tubulo-interstitial changes (r-0.47), ADC correlated only with interstitial infiltrations (r-0.44). Flow-related diffusion parameters showed high standard deviation. Conclusions: IVIM imaging is sensitive to functional and morphologic changes in CKD. The separation of influence of Fp from true diffusion improves the assessment of chronic changes in renal parenchyma.

Background Non-invasive alternatives to percutaneous renal biopsy are sought for follow-up of renal allografts. Purpose To evaluate the feasibility of intravoxel incoherent motion (IVIM) imaging in monitoring and predicting the function of renal allografts. Material and Methods Thirty-five kidney recipients were examined on a 1.5-T MR unit approximately three and 18 months after transplantation. Based on estimated glomerular filtration rate (eGFR), patients were divided into three groups: improved; declined; and stable graft function. Diffusion parameters were calculated with the use of monoexponential (total apparent diffusion coefficient [ADCT]) and biexponential (pure diffusion coefficient [D], perfusion fraction [Fp]) model and compared among and within study groups using Kruskal–Wallis, Mann–Whitney, and Wilcoxon matched pairs tests. Diffusion parameters were correlated with eGFR using Spearman’s rank correlation coefficients. Results of tests with P values < 0.05 were considered statistically significant. Results Values of diffusion parameters, especially Fp, were lower in patients with a declined graft function; however, statistically significant intergroup differences were observed only in a limited number of parameters at the time of follow-up magnetic resonance imaging (MRI). None of the diffusion parameters from the baseline MRI correlated with the change in eGFR over time. Flow-related diffusion parameters calculated with the IVIM model showed high variability. Conclusion We observed a trend toward a decrease in values of diffusion parameters in patients with a declined graft function. Further research is needed to verify a clinical usefulness of this observation.

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