Value of ultra-high b-value diffusion-weighted imaging for the evaluation of renal ischemia-reperfusion injury

To explore the feasibility of ultra-high b-value diffusion-weighted imaging (^ubDWI) in assessment of renal IRI. Thirty-five rabbits were randomized into a control group (n = 7) and a renal IRI group (n = 28). The rabbits in the renal IRI group underwent left renal artery clamping for 60 min. Rabbits underwent axial ^ubDWI before and at 1, 12, 24, and 48 h after IRI. Apparent diffusion coefficient (ADC_st) were calculated from ^ubDWI with two b-values (b = 0, 1000 s/mm²). Triexponential fits were applied to calculate the pure diffusion coefficients (D), perfusion-related diffusion coefficient (D^⁎), and ultra-high ADC (ADC_uh). The interobserver reproducibility were evaluated. The repeated measurement analysis of variance and Spearman correlation analysis was used for statistical analysis. The ADC_st, D, and ADC_uh values showed good reproducibility. The ADC_st, D, and D^⁎ values of renal Cortex (CO) and outer medulla (OM) significantly decreased after IRI (all P < 0.05). The ADC_uh values significantly increased from pre-IRI to 1 h after IRI (P < 0.05) and significantly declined at 24 h and 48 h after IRI (all P < 0.05). ADC_uh was strongly positively correlated with AQP-1 in the renal CO and OM (ρ = 0.643, P < 0.001; ρ = 0.662, P < 0.001, respectively). ^ubDWI can be used to non-invasively evaluate early renal IRI, ADC_uh may be adopted to reflect AQP-1 expression.