Collecting system involvement by renal tumor: are CT measurements reliable enough?

Abstract

Smaller kidney lesions which are more often detected recently by accidental imaging are amenable for nephron sparing approach whether at open surgery, laparoscopy or ablative techniques. The pretreatment planning is based on multiplanner CT expected to well define the relationship of the lesion to the major renal blood vessels and collecting system (CS). This study is aimed to compare the pre-surgical CT measurements of the distance from tumor to CS to the actual distances observed on radical nephrectomy specimens. Contrast CT of 39 patients with renal cell carcinoma (RCC) underwent measurements of the distance between CS and renal tumor. All measurements were confronted with the measurements performed on radical nephrectomy specimens of the same patients. Of all 39 patients in 34 (87%) CT showed a contact relation between the tumor and the CS. In fact, the CS involvement has been histologically proven only in three (7.6%) cases. Cutting off the measurements at thresholds of 2 and 5 mm also showed a significant discrepancy between CT and specimen measurements. The trend of NSS and ablative techniques stressed out the importance of pretreatment measurements of the distance between the tumor and the CS. This study as performed on radical nephrectomy specimens points out the overestimated proximity of the tumor to the CS. These data if confirmed by other studies, may play a role while planning the management of NS approaches.