Ultrasound Localization Microscopy for the Assessment of Microvascular Abnormalities in Transplant Renal Artery Stenosis.

Objective: To evaluate the clinical validity of ultrasound localization microscopy (ULM)-based microvasculomics for quantitatively detecting microcirculatory dysfunction in transplant renal artery stenosis (TRAS).

Methods: In this study, 54 renal transplant recipients underwent digital subtraction angiography (DSA) and ultrasound examination. They were divided into TRAS (n = 15) and control (n = 39) groups. Using ULM imaging derived from contrast-enhanced ultrasound (CEUS) videos, the study compared microvascular morphological, velocity, and comprehensive parameters between the groups.

Results: Baseline characteristics and most Doppler and CEUS parameters were comparable between the groups, with the exception of the segmental artery resistance index (RI). ULM analysis revealed that, compared to controls, TRAS patients exhibited significantly lower vessel ratio, mean velocity, vessel count, perfusion index, and location velocity. These parameters were significantly correlated with serum levels of renal allograft function markers. Multivariate LASSO regression identified four discriminative parameters: vessel count, perfusion index, velocity entropy, and segmental artery RI. ROC analysis demonstrated that combining these parameters achieved an AUC of 0.84 (95% CI = 0.72-0.97) for TRAS prediction, with a sensitivity of 93.3%.

Conclusion: Ultrasound microvasculomics provides detailed insights into the microvascular structure and hemodynamics of TRAS, presenting a promising novel tool for monitoring and early intervention in renal allograft microstructural pathology.