Predicting the histology of renal masses using preoperative Doppler ultrasonography

Traditional imaging techniques cannot differentiate among benign, indolent and malignant renal neoplasms. Since conventional clear cell carcinomas are highly vascular, we used preoperative color and/or power Doppler ultrasonography to evaluate the association between vascular flow in a renal mass and surgical pathology.

Nephrectomies performed at our institution between January 2001 and December 2004 were retrospectively evaluated. Any detection of flow in the renal mass on color Doppler ultrasonography was defined as vascular flow. A prospective validation study was then performed from January 2005 to October 2005 and a nomogram was constructed to predict clear cell histology.

Of 299 renal lesions in the retrospective cohort 210 (70%) had evidence of vascular flow, including 156 of 169 conventional clear cell carcinomas (92%) (p <0.0001). On logistic regression analysis vascular flow was associated with conventional clear cell histology (OR 16.9, 95% CI 8.7-32.8; p <0.0001). This finding was validated prospectively in 97 patients. Vascular flow was detected in 54 of 65 renal masses (83%) with conventional clear cell histology (p <0.0001), which was associated with an OR of 10.8 (95% CI 4.0-29.0; p <0.0001). A nomogram incorporating vascular flow along with clinical variables (clinical size, patient sex and age) to predict conventional clear cell histology was constructed on the retrospective cohort and validated on the prospective data set (concordance index 0.82 and 0.76, respectively).

Vascular flow detected by color Doppler ultrasonography is strongly associated with conventional clear cell histology. A nomogram incorporating vascular flow on color Doppler ultrasonography and clinical parameters may aid in the preoperative characterization of renal lesions.