The pathology of renal tumors

Helical and electron beam CT scanning in the evaluation of renal vein involvement in patients with renal cell carcinoma

PURPOSE

The purpose of this study was to assess helical and electron beam CT scanning in the evaluation of renal vein involvement in patients with renal cell carcinoma (RCC).

METHOD

Seventy-three patients with 76 pathologically proven RCC who underwent surgical resection or autopsy were evaluated for the accuracy of helical and electron beam CT scanning in the detection of renal vein tumor thrombus in patients with RCC. Patients were entered into the study only if they were scanned on either electron beam or helical CT scanners with intravenous contrast medium enhancement. The tumors involved the right kidney in 38 cases and the left kidney in 38 cases, with tumor size ranging from 1.5 to 19 cm (mean 7 cm). The pathologic grade of the tumor was Grade I in 21, Grade II in 37, Grade III in 15, and Grade IV, in 3 patients.

RESULTS

The accuracy of preoperative CT evaluation of the renal vein for presence or absence of tumor thrombus was 96%. The negative predictive value was 97% and the positive predictive value was 92%. Sensitivity was 85% with a specificity of 98%. In two cases we were unable to detect small intrarenal venous thrombus, although this was present on a microscopic level and did not affect surgical resection. A single false-positive CT result occurred secondary to unopacified blood flow from a capsular vein into the affected renal vein, resulting in a small flow void on CT.

CONCLUSION

The data show that preoperative staging of the renal vein in the patients with RCC is effectively provided with helical and electron beam CT scanning.