Super-resolution Ultrasound Combined with Contrast-enhanced Ultrasound: An Exploratory Approach for Differentiating Benign From Malignant Renal Tumors Based on Microvascular Characteristics.

RATIONALE AND OBJECTIVES: This study aimed to explore the diagnostic value of super-resolution ultrasound (SRUS) in differentiating benign from malignant renal solid tumors by assessing microvascular characteristics, and to find if combining SRUS with conventional ultrasound (US) and contrast-enhanced ultrasound (CEUS) potential enhances diagnostic utility. MATERIALS AND METHODS: This prospective study included 114 pathologically confirmed renal lesions. All patients underwent conventional US, CEUS, and SRUS. We analyzed qualitative and quantitative parameters of CEUS and SRUS, screened significant parameters by univariate analysis, and used a comprehensive diagnostic score method for exploratory receiver operating characteristic (ROC) analysis to construct multiparametric diagnostic panels. Diagnostic performance was evaluated using the area under the receiver operating characteristic curve area under the curve (AUC). RESULTS: Among 114 masses (88 malignant, 26 benign), malignant lesions exhibited more tortuous vessels and higher microvascular image complexity (p < 0.05). After normalization, microvascular density (MVD) and microbubble velocity showed high spatial heterogeneity in malignancies. CEUS excelled in macroscopic perfusion (AUC=0.842), while SRUS provided incremental microscopic structural information (AUC=0.678); both outperformed conventional US (AUC=0.638). Crucially, the combination of SRUS and CEUS demonstrated improved diagnostic performance (AUC=0.871) in this cohort, suggesting potential complementary value over either modality alone. CONCLUSION: SRUS non-invasively reveals unique microvascular architecture and heterogeneity in renal malignancies. The combined SRUS-CEUS approach shows promise for improving differential diagnostic accuracy. These results are exploratory and provide preliminary evidence for the potential value of SRUS in renal tumor diagnosis. Key limitations include a relatively small proportion of benign tumors, lacking correction for multiple comparisons, and lack of integration with CEUS time-intensity curve quantitative parameters.