Prediction of high-grade ureteral urothelial carcinoma on CT urography

Objective: To evaluate the correlation between CT urography (CTU) findings and histological grade of ureteral urothelial carcinoma (UUC), and to identify predictors of high-grade UUC. Methods: CTU images of 73 patients with pathologically proven UUC via nephroureterectomy were independently reviewed by two radiologists for tumour size, tumour location, hydronephrosis grade, periureteral infiltration, presence of enlarged retroperitoneal lymph nodes and tumour enhancement value. Interobserver agreement was assessed with kappa statistics. Histological grade was classified as either low or high according to the WHO 2004 classification system and pathologic T stage was assessed according to the TNM staging system. Binary logistic regression, Spearman correlation analysis and receiver operating characteristic curves were used to evaluate relationships between CTU findings and histological grade. Results: 58 patients had high-grade UUCs and 15 had low-grade UUCs. Among CTU features, only hydronephrosis grade was significantly correlated with high tumour grade for both readers (p < 0.001). Multivariate logistic regression revealed that hydronephrosis of Grade 3 or higher was a significantly independent predictor of high-grade UUC for both readers (p ≤ 0.004). Interobserver agreement was excellent for hydronephrosis grade (= 0.862). With the cut-off value of hydronephrosis Grade 3, the sensitivity, specificity and area under the curve for predicting high-grade UUC were, respectively, 88%, 79% and 0.830 for reader 1 and 86%, 80% and 0.763 for reader 2. Conclusion: Hydronephrosis of Grade 3 or higher on CTU may be predictive of high-grade UUC. Advances in knowledge: Radical surgery should be considered for UUC causing hydronephrosis of Grade 3 or higher on CTU, even in small tumours without periureteral infiltration.