Kidney Transplant:Functional Assessment With Diffusion-weighted Imaging And Diffusion Kurtosis Imaging

Part Ⅰ:Functional evaluation of transplanted kidneys with reduced field of view diffusion-weighted imagingObjective:To determine whether reduced field of view diffusion-weighted imaging (rFOV DWI) with multi-b values allows detecting functional variability in transplanted kidneys.Methods:Multi-b rFOV DWI was performed on 46 renal transplantation recipients.18 patients presented with estimated glomerular filtration rate (eGFR)≥ 60 ml/min/1.73m2 (Group 1),20 patients with 30≤eGFR≤60 ml/min/1.73m2 (Group 2) and 8 patients with eGFR< 30 ml/min/1.73m2 (Group 3). Apparent diffusion coefficient (ADCT), pure diffusion (ADCD) and perfusion fraction (Fp) were calculated and compared among three groups. Correlations between imaging parameters and eGFR were also assessed.Results:The diffusion-weighted images were presented with high resolution and significant corticomedullary difference. In cortex, ADCT and Fp values showed significant differences among groups (p<0.02 and p<0.001 respectively). ADCT was significantly higher in Group 1(1.64±0.14)×10-3 mm2/s and Group 2 (1.58±0.18)×10-3mm2/s than Group 3 (1.44±0.11)×10-3 mm2/s (p<0.05), and the differences in FP values between each two groups were statistically significant (p<0.05) (Group 1,2 and 3:0.31±0.03,0.28± 0.04 and 0.25±0.03, respectively). Cortical ADCT, Fp and medullary FP correlated positively and significantly with eGFR.Conclusion:Multi-b rFOV DWI in renal allografts is a promising non-invasive tool for functional monitoring.Part Ⅱ:Functional evaluation of transplanted kidneys with diffusion kurtosis imagingObjective:To investigate the potential of diffusion kurtosis imaging (DKI) for non-invasively assessing the function of renal allografts.Methods:Eleven renal transplant recipients were prospectively recruited in this study and examined at a 3 T magnetic resonance scanner. Region-of-interest (ROI) measurements were performed to determine fractional anisotropy (FA), mean kurtosis (MK), axial kurtosis (Ka) and radial kurtosis (Kr) of the cortex and the medulla of the kidneys. Two-tailed paired Student t tests were used to compare DKI parameters in cortex and medulla. Relationships between DKI parameters and serum creatinine (Scr) as well as eGFR, were assessed by using Pearson correlation coefficient.Results:FA was significantly greater in medulla than in cortex, while cortical Ka showed significant greater values than medullary Ka. Cortical MK (r=0.683, p=0.021), Ka (r= 0.735, p=0.010), Kr (r=0.605, p=0.049) and medullary Ka (r=0.747, p=0.008) correlated positively and significantly with Scr. Cortical MK (r=-0.832, p-0.002), Ka (r =-0.893, p<0.001), Kr (r=-0.750, p=0.008) and medullary Ka (r=-0.710, p=0.014) showed a negative and significant correlation with eGFR.Conclusion:It is possible that DKI may serve as an effective and non-invasive model for functional evaluation of transplanted kidneys.