To explore the feasibility of evaluating renal ischemia-reperfusion injury (IRI) at different time by using T₂^*mapping.

Eighteen New Zealand white rabbits were used to build therenal IRI injury model by blocked the left renal arteries and veins by using noninvasive arterial clip, left renal ischemia-reperfusion was performed by clamping of the left renal pedicle for 60 minutes, followed by reperfusion. All the rabbits underwent MRI examination including axial T₂WI and T₂^*mapping before scanning and 1 h, 12 h, 24 h and 48 h after reperfusion. Every two rabbits were randomly sacrificed at 1 h, 12 h, and 24 h after reperfusion. The rest of the rabbits were sacrificed for pathological examination at 48 h after reperfusion. All specimens were cut into slices and stained with hematoxylin-eosin (HE). The values of T₂^*, R₂^* and the pathological scores of cell edema, cell necrosis, interstitial inflammation and tubular castin renal tissues at different time points were measured. Repetitive measurement deviation analysis was performed to compare difference of T₂^* and R₂^* at 5 time-points. The relationship between the value of T₂^* and R₂^* in renal tissues and the scores of cell edema, cell necrosis, interstitial inflammation and tubular castin renal tissues was analyzed by Spearman correlation analysis.

T₂^* value and R₂^* value in both inner medulla and outer medulla were statistically significant (P<0.05), while there was no statistically significant in the cortex (P>0.05).Pairwise comparison of T₂^* and R₂^* at different time points in the cortex showed statistically significant difference between before and 24 h,before and 48 h, 12 h and 48 h were statistically significant (P<0.05), while the remaining were no statistically significant difference (P>0.05).T₂^* value of the outer medullar after IRI positively correlated with the scores of cell edema, interstitial inflammation and tubular castin renal tissues (r values were 0.57, 0.38, 0.33; P<0.05). R₂^* value of the outer medullar after IRI negatively correlated with the scores of cell edema (r value was -0.52, P<0.05).

T₂^* mapping could reflect the dynamic changes in different zones and different time points after renal IRI, especially in the outer medullary band which has good consistency with pathological score.

Magnetic resonance imaging; Reperfusion injury; T₂^*mapping