IVIM-DWI of transplanted kidneys: reduced diffusion and perfusion dependent on cold ischemia time.

ABSTRACT

PURPOSE: To evaluate the effect of cold ischemia time (CIT) of renal allografts on diffusion and perfusion using intravoxel incoherent motion (IVIM) derived parameters. MATERIAL AND METHODS: A total of 37 patients with renal allografts (CIT 27 <15 h, 10 ≥15 h) and 30 individuals with healthy kidneys were examined at 1.5 T using a single-shot echo-planar diffusion-weighted pulse sequence with nine b-values ranging from 0 to 800 s/mm(2). ADC, perfusion fraction f, and the diffusion coefficient D were calculated using the IVIM model. Parameters of allografts stratified by CIT were compared with healthy kidney groups using the Mann-Whitney U test for unpaired data. We computed the Spearman correlation coefficient for correlation with creatinine values. RESULTS: ADC, D, and f of transplanted kidneys were significantly lower than in the healthy controls. The long-CIT group showed significantly lower diffusion parameters compared with the short-CIT group [mean±SD] ADC 1.63±0.14 µm(2)/ms, f 11.90±5.22%, D 1.55±0.25 µm(2)/ms versus ADC 1.79±0.13 µm(2)/ms, f 16.12±3.43%, D 1.73±0.14 µm(2)/ms, P(ADC), (f), (D)<0.05. CONCLUSION: Our results suggest that diffusion parameters, especially the ADC, depend on the CIT of the kidney allograft. Potentially, this stands for functional changes in renal allografts. Diffusion-weighted imaging could be used for follow-up examinations. Thus, diffusion parameters may help guide therapy in patients with delayed graft function.