Diagnostic accuracy of preoperative computed tomography used alone to detect lymph-node involvement at radical nephrectomy.

OBJECTIVE

The aim of this study was to compare preoperative computed tomography (CT) with pathological findings in patients undergoing lymphadenectomy at the time of nephrectomy for renal cancer-associated lymphadenopathy.

MATERIALS AND METHODS

Data from 515 consecutive nephrectomy surgeries (2004-2012) in a single university-affiliated centre were analysed to identify patients who had undergone lymph-node dissection concomitant with nephrectomy. Preoperative CT imaging was subjected to multiple repeated independent blinded reviews (two radiologists and one surgeon, each individually and on two separate occasions). Retroperitoneal lymph-node status was subjectively categorized (in a manner not based purely on size criteria) at each review as: 1 = unequivocally positive, 2 = equivocally positive, 3 = equivocally negative, or 4 = unequivocally negative. These findings were compared with pathological analysis, and interobserver and intraobserver agreement was assessed using non-weighted kappa () statistics.

RESULTS

In total, 71 patients were stratified as category 1 (n = 18), 2 (n = 14), 3 (n = 31) and 4 (n = 8); pathological lymph-node metastasis was present in 14 (78%), four (28%), four (13%) and zero patients, respectively. Sensitivity, specificity, positive and negative predictive values for preoperative CT were 82%, 71%, 56% and 90%, respectively. Intraobserver agreement was greater for the radiologists (values 0.490, 0.540) than for the surgeon (value 0.393). Interobserver agreement was strongest for radiological category 1 (unequivocally positive; value 0.75). Receiver operating characteristics curves did not reveal significant differences in any observer accuracy.

CONCLUSION

Contrary to concerns about a high false-positive rate, metastasis within regional lymph nodes can be predicted with reasonable accuracy by preoperative CT imaging alone.