Radio-Guided Lymph Node Mapping in Bladder Cancer Using SPECT/CT and Intraoperative γ-Probe Methods.

PURPOSE: Lymph outflow from bladder tumor differs between individuals, making the prediction of the metastatic landing sites difficult. A "blind" template of lymphadenectomy has been tested as a solution to this problem. We believe that it is feasible to find methods enabling more precise lymph nodes (LNs) evaluation. The aims of our study were to evaluate the possibility of LNs mapping in case of muscle invasive bladder cancer (MIBC) and to compare the 2 methods of their detection.

PATIENTS AND METHODS: Our study group consisted of 38 cN0 MIBC patients. Lymph nodes mapping was performed by SPECT/CT lymphoscintigraphy using Tc-nanocolloid, followed by intraoperative verification with γ-ray probe. Lymph nodes with increased radiotracer uptake (hot spots) were removed, and then pelvic LNs dissection was conducted. Lymph nodes resected as hot spots and LNs resected with lymphadenectomy were separately examined by a pathologist.

RESULTS: An average of 3 hot spots (range, 1-5) were identified in each case. For 36 of 38 patients, both preoperative SPECT/CT and intraoperative γ-probe evaluation results were obtained. Ninety-five percent of hot spots were found distally and caudally to the uretero-iliac crossing; 5% were found proximal. Lymph nodes outside the pelvic LNs dissection area did not contain metastases. In 2 patients, metastases were found in LNs without increased radiotracer uptake, and the observed hot spots contained no metastases.

CONCLUSIONS: Radio-guided LNs mapping in case of MIBC is feasible. Preoperative detection of hot spots using SPECT/CT and intraoperative γ-ray detection probe gives similar results.