Associations between contrast-enhanced ultrasound features and WHO/ISUP grade of clear cell renal cell carcinoma: a retrospective study

BackgroundClear cell renal cell carcinoma (CCRCC) comprises 70%-80% of RCCs. The World Health Organization/International Society of Urology Pathology (WHO/ISUP) classification is the most important prognostic factor for CCRCC. By evaluating the variations of tumor microvascular density, contrast-enhanced ultrasound (CEUS) can noninvasively predict the WHO/ISUP grade of CCRCC, and provide the appropriate treatment plan before clinical operation. MethodsIn this study, we used CEUS features to analyze 116 CCRCC cases and assess the value of correlation between each indicator and CCRCC WHO/ISUP grading. ResultsWhen compared to high-grade (WHO/ISUP grade III/IV) tumors, low-grade (WHO/ISUP grade I/II) tumors had reduced relative peak intensity (Delta PI) (P = 0.021), relative area under the curve (Delta AUC) (P = 0.019). However, the frequency of incomplete pseudocapsule (P = 0.021) was significantly higher in high-grade tumors. A cut-off value of mean diameter > 5.5 cm, Delta PI > 304 x 10-3, Delta AUC > 350 x 10-3 allowed identification of high-grade tumors with an area under the curve (AUC) of 74.6%, 71.7%, 70.7%, respectively (95% confidence interval). ConclusionsThe features of CEUS are effective for differentiating high-grade tumors from low-grade tumors, thus CEUS can be considered an acceptable method for the preoperative assessment of tumor grade.