Diagnostic Value of Qualitative and Quantitative Contrast‐Enhanced Ultrasound for Pathological Subtypes of Small Solid Renal Masses

Objectives To assess the diagnostic value of qualitative and quantitative contrast‐enhanced ultrasound (CEUS) for pathological subtypes of small solid renal masses (sSRMs). Methods Patients with sSRMs confirmed by surgical pathology from January 2019 to November 2021 were retrospectively identified. All patients were divided into 3 groups: clear cell renal cell carcinoma (ccRCC) group, none‐ccRCC group (renal cell carcinoma other than ccRCC), and angiomyolipoma (AML) group. The mass position, size, echogenicity and blood flow signals were compared. The speed of wash‐in, wash‐out, the degree of peak enhancement and the homogeneity at peak enhancement, the presence of pseudocapsule sign in CEUS imaging were qualitatively evaluated. Peak enhancement, wash‐in area under the curve (WiAUC), rise time, time to peak, wash‐in rate (WiR), wash‐in perfusion index (WiPI) and tumor‐to‐cortex enhancement ratio of the above parameters in CEUS imaging were quantitatively evaluated. Results Of 105 patients, 105 sSRMs (66 ccRCC, 18 none‐ccRCC, 21 AML) were enrolled in this study. No significant differences were found on location, size and echogenicity among 3 groups (all P > .05). The proportion of fast‐washout and hypo‐enhancement were highest in none‐ccRCC group. Heterogeneous enhancement was detected in 87.88% in ccRCC group which is significantly higher than other 2 groups. Hundred percent of the AML showed no pseudocapsule sign, which is the highest among the 3 groups. Peak enhancement, WiAUC, WiR, WiPI of ccRCC group were the highest among the 3 groups. Conclusions Qualitative and quantitative CEUS not only has the diagnostic value in distinguishing AML from malignant sSRMs, but also helps to differentiate the pathological subtypes of sSRMs.