Contrast-Enhanced Ultrasound to Assess Kidney Quality During Ex Situ Normothermic Machine Perfusion

Area of Science:

• Nephrology
• Medical Imaging
• Transplantation Science

Background:

• Normothermic machine perfusion (NMP) is crucial for assessing donated kidney viability.
• Assessing microvascular perfusion is key, as diminished flow underlies ischemia-mediated acute kidney injury.
• Contrast-enhanced ultrasound (CEUS) offers a potential method for objective microvascular assessment during NMP.

Purpose of the Study:

• To evaluate the utility of CEUS for quantifying microvascular perfusion in porcine and human kidneys during NMP.
• To correlate CEUS findings with biomarkers of kidney injury and apoptosis.
• To develop tools for quantitative CEUS analysis.

Main Methods:

• Blood-based NMP was performed on porcine and human kidneys.
• CEUS was administered via a contrast bolus into the NMP arterial limb.
• Microvascular perfusion was quantified, and a CEUS-score was derived using z-score normalization.

Main Results:

• In porcine kidneys, poor microvascular perfusion correlated with increased urinary NGAL and DNA fragmentation.
• In human kidneys, the 2-hour CEUS-score strongly correlated with histological DNA fragmentation (r = -0.937) and predicted 24-hour urinary NGAL (r = -0.925).
• Total renal blood flow did not correlate with these injury markers.

Conclusions:

• CEUS provides objective, point-of-care microvascular perfusion assessment during renal NMP.
• The early CEUS-score shows predictive value for later kidney injury markers.
• CEUS is a promising tool for kidney quality assessment in centers focused on organ reconditioning and transplantation.