Accuracy of color Doppler sonography in assessing venous thrombus extension in renal cell carcinoma

OBJECTIVE. Our objective was to evaluate the accuracy of color Doppler sonography for assessing tumor thrombus extension into the renal veins, the inferior vena cava, and the right side of the heart in patients with renal cell carcinoma. MATERIALS AND METHODS. Over the past 4.5 years, 44 patients with 46 renal cell carcinomas were examined with color Doppler sonography for the presence and extent of tumor thrombus in the renal veins, the inferior vena cava, and the right side of the heart Examinations were performed after an equivocal CT scan in 34 patients and as a primary imaging technique in 10. Color Doppler sonographic findings were correlated with surgical-pathologic findings or findings from autopsies performed within 3 months of the Doppler study. Seven patients were excluded: two because of poor technical quality caused by body habitus and five because pathologic correlation was performed more than 3 months after the color Doppler sonographic examination. The remaining 39 renal vein and 37 caval Doppler examinations constituted the study material. Criteria used for the diagnosis of tumor thrombus included distention of the renal vein or the inferior vena cava by echogenic material and partial or complete absence of flow detected with color Doppler sonographic examination. RESULTS. Sixteen of 39 renal veins evaluated had pathology-proven tumor thrombus. Color Doppler sonography was 87% accurate with a sensitivity of 75%, a specificity of 96%, a positive predictive value of 92%, and a negative predictive value of 85%. In two false-positive cases, involvement was limited to intrarenal veins, causing no change in the surgical approach. Five of 37 inferior venae cavae evaluated had proven involvement by tumor thrombus. Color Doppler sonography was 100% accurate in assessing the presence and extent of inferior vena caval involvement by tumor thrombus. Extension into the right atrium and ventricle that was shown by this technique was proven by surgery in one case. The overall accuracy for detecting venous involvement for both the renal veins and the inferior vena cava was 93%, the sensitivity was 81%, and the specificity was 98%. CONCLUSION. In patients with renal cell carcinoma, color Doppler sonography appears to be fairly accurate in assessing tumor extension into the renal veins, the inferior vena cava, and the right side of the heart. Although CT is the primary imaging technique for staging renal cell carcinoma, color Doppler sonography may be used as a complementary technique for assessing venous extension in patients with an equivocal CT examination.