The role of multimodal ultrasound in assessing renal microcirculatory perfusion in cases of acute kidney injury.

PURPOSE: This study seeks to evaluate renal microcirculatory perfusion in patients with acute kidney injury (AKI) utilizing two-dimensional ultrasound, Color Doppler Flow Imaging (CDFI), and renal Contrast-Enhanced Ultrasound (CEUS). In addition, the study aims to investigate the relationship between renal microcirculation perfusion and serum cystatin C, a sensitive indicator of renal function. METHODS: A cohort comprising 41 patients with acute kidney injury (AKI) was stratified into two groups: AKI recovery group and AKI non-recovery group. Multimodal ultrasound parameters were evaluated by univariate logistic regression, and the prognostic value of these parameters for AKI patients was evaluated by receiver operating characteristic (ROC) analysis. Additionally, Spearman correlation analysis was utilized to investigate the relationship between serum cystatin C levels and quantitative parameters obtained through contrast-enhanced ultrasound (CEUS). RESULTS: Significant differences were observed in renal cortical resistance index (RI), semi-quantitative renal perfusion (SQP), half-peak width time (TWH), area under the curve (AUC)-time-intensity curve (TIC), washed-in area under the curve (WiAUC), and washed-out area under the curve (WoAUC) between the two groups (P < 0.05). The receiver operating characteristic (ROC) analysis of the area under the time-intensity curve (TIC) demonstrated the highest diagnostic efficacy (AUC-ROC = 0.816, 95% CI: 0.678–0.954). Furthermore, a statistically significant difference was found in serum cystatin C levels between the two groups (P = 0.002), showing a negative correlation with the contrast-enhanced ultrasound (CEUS) quantitative parameters of time to peak (Ttop), time to washout ratio (TWR), and the washed-in area under the curve (WiAUC) in both groups. CONCLUSION: Renal contrast-enhanced ultrasound (CEUS) offers a more comprehensive and accurate assessment of renal microcirculatory perfusion in AKI patients, showing a strong correlation with serum cystatin C, a sensitive indicator of renal function. CLINICAL TRIAL NUMBER: Not applicable.