Evaluation of renal ischemia-reperfusion injury using CEUS in mice.

Background: Renal ischemia-reperfusion injury (IRI) frequently occurs clinically. We investigated the value of contrast-enhanced ultrasonography (CEUS) in the evaluation of renal IRI levels in mice.

Methods: Thirty-six healthy adult male C57BL/6 mice (20-22 g) were randomly divided into the sham, 10 min, 20 min, 30 min, 40 min, and 50 min groups based on the time of renal warm ischemia by blocking the left renal pedicle, approved by the Institutional Animal Ethics Committee. Time-intensity curve (TIC)-derived parameters such as peak enhancement (PE) and wash-in perfusion index (WiPI) were produced using CEUS at 1 h and 24 h after IRI. The severity of kidney injury was detected by the renal tubular necrosis rate which was analyzed by hematoxylin and eosin staining at 24 h after IRI. The Spearman correlation coefficient was used to describe the correlations between PE and WiPI values and the renal tubular necrosis rate.

Results: The PE and WiPI values decreased after IRI in the groups with a warm ischemia time ≥ 20 min. The renal tubular necrosis rate was significantly correlated with the PE value at 1 h (ρ = -0.802) and 24 h (ρ = -0.861) after IRI and the WiPI value at 1 h (ρ = -0.814) and 24 h (ρ = -0.853) after IRI (all p < 0.001).

Conclusion: TIC-derived parameters, including PE and WiPI values, can be used to evaluate the severity of renal IRI in mice. CEUS is a safe and effective technology for the detection of renal IRI.

Relevance Statement: CEUS can evaluate the severity of renal ischemia-reperfusion injury by peak enhancement and wash-in perfusion index values selected from various time-intensity curve-derived parameters.

Key Points: • Contrast-enhanced ultrasonography can evaluate the level of renal ischemia-reperfusion injury. • Peak enhancement and wash-in perfusion index are correlated with the renal tubular necrosis rate. • CEUS can detect changes in unilateral renal function without radiation.