Ultrasound molecular imaging in evaluating the severity of ischemia-reperfusion injury-induced acute kidney injury

Acute kidney injury (AKI) is a global public health issue for which the prognosis varies, depending on the severity. Early and accurate assessment of the severity of AKI is crucial for determining the prognosis of patients. Ultrasound molecular imaging (USMI) technology can be used to evaluate AKI, but studies on assessing the inflammatory responses of different severity levels of AKI have not been reported. Therefore, this study aimed to explore the early value of USMI technology based on vascular cell adhesion molecule-1 (VCAM-1) targeted microbubbles in monitoring the severity of AKI at the molecular level.

A total of 66 mice were randomly divided into a mild ischemia-reperfusion injury (IRI)-AKI (m-AKI) group, severe IRI-AKI (s-AKI) group, and sham operation group (sham group). USMI was used to monitor renal inflammatory responses to different injury levels in AKI. Pearson's correlation was used to analyze the correlation between USMI and pro-inflammatory factors and VCAM-1 protein expression. Receiver operating characteristic (ROC) curves were drawn to investigate the efficacy in diagnosing mild and severe AKI at different reperfusion time points.

The normalized intensity difference (NID) at different reperfusion time points (0.5, 2, 6, 12, and 24 h) in the s-AKI group was higher than that in the m-AKI group (P<0.05). NID was positively correlated with VCAM-1 protein expression, tumor necrosis factor-alpha (TNF-α), and interleukin-6 (IL-6) levels (r=0.852, 0.794, and 0.748, respectively, all P<0.05). The NID had good diagnostic efficacy in diagnosing the degree of injury in AKI at various reperfusion time points. The area under the ROC curve (AUC) of NID was 0.895 [95% confidence interval (CI): 0.813-0.977], which is superior to serum creatinine (Scr), blood urea nitrogen (BUN), cystatin C (Cys-C), kidney injury molecule-1 (KIM-1), and neutrophil gelatinase-associated lipocalin (NGAL) (P<0.05).

USMI can be used in the early assessment of the renal inflammatory response of different degrees of AKI, which is superior to commonly used renal function assessment indicators and early biomarkers. USMI may provide helpful information for the diagnosis and assessment of the severity of AKI.