In situ assessment of renal cortical microcirculation in septic acute kidney injury rats using contrast-enhanced ultrasound and sidestream dark-field imaging.

Purpose: To evaluate in situ assessment of renal cortical microcirculation (RCM) in S-AKI rats using CEUS and SDF imaging.

Methods: CLP was performed to induce S-AKI in Sprague-Dawley rats; Sham rats served as control. CEUS and SDF imaging were sequentially applied at postoperative 24 h and 48 h to investigate the RCM.

Results: At postoperative 24 h and 48 h, CLP rats exhibited hemodynamic deterioration and AKI. Renal injury score and positive staining for pimonidazole were significantly increased (p < 0.05). In CLP rats, parameters of RCM, including peak enhancement (PE), rise time (RT), PE/RT, time to peak (TTP), total small vessel density (TVD), perfused small vessel density (PVD), microvascular flow index (MFI), and proportion of perfused vessels (PPV) were significantly deteriorated compared to Sham rats (p < 0.05). In CLP rats, Lac was significantly negatively correlated with PE, PE/RT, TVD, PVD, PPV and MFI, and significantly positively correlated with RT and TTP. TVD, PVD, PPV and MFI were significantly positively correlated with PE and PE/RT and negatively correlated with RT and TTP.

Conclusion: The RCM of S-AKI rats exhibited decreased blood perfusion and heterogeneity in early sepsis. CEUS and SDF imaging are effective methods for detecting the RCM.