Evaluation of renal microperfusion in hyperuricemic nephropathy by Contrast-Enhanced Ultrasound imaging

Objective Diagnostic tools for the early detection of renal injury caused by hyperuricemia are still lacking. We investigated whether contrast-enhanced ultrasound (CEUS) could be used as a diagnostic tool for hyperuricemic nephropathy (HN). Methods HN rats were generated by oral administration of a mixture of adenine and potassium oxonate for 4 weeks. In addition, 10 healthy volunteers and 40 CKD (stages 1-4) patients with HN were enrolled. CEUS was performed, and low acoustic power contrast-specific imaging was used for quantitative analysis. Time-intensity curves (TICs) and quantitative indexes were created by Qlab software. Results In the HN rat model, CEUS detected a significant decline in renal cortical perfusion, as reflected by a lower peak intensity (PI) value (25.43±1.31 vs. 37.9±1.75 db) and longer time to reach peak intensity (TTP) (34.5±5.9 vs. 8.58±1.6 s) than those of control rats at one week after administration of adenine and potassium oxonate, and this decline became more pronounced at 4 weeks (PI, 15.93±0.40 db; TTP, 61.4±3.9 s). PI values correlated significantly with serum Kim-1 levels and fibrosis scores in HN rats. An early decline in PI values was also observed in CKD stage 1 patients with HN compared to the control subjects (61.1±4.52 vs. 65.80±7.10 db) and correlated with renal function in the patients with HN. In contrast, an increase in TTP values was detected in HN patients with stage 1 CKD (15.14±1.75 vs. 14.52±4.75 s) and was more pronounced in CKD stage 4 patients (67.32±3.29 s). Conclusion CEUS was able to detect abnormal renal perfusion in early CKD with HN, which correlated with renal function decline, suggesting that CEUS could be used as a noninvasive tool for assessing renal function in patients with HN.