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

Area of Science:

• Urology
• Nuclear Medicine
• Oncology

Background:

• Predicting lymph node metastasis in bladder cancer is challenging due to variable lymphatic drainage.
• Standard lymphadenectomy templates may not accurately target all metastatic lymph nodes.
• Improved methods for lymph node evaluation are needed for muscle-invasive bladder cancer (MIBC).

Purpose of the Study:

• To evaluate the feasibility of lymph node mapping in MIBC patients.
• To compare two methods for detecting metastatic lymph nodes: SPECT/CT lymphoscintigraphy and intraoperative gamma-ray probe detection.

Main Methods:

• 38 cN0 MIBC patients underwent SPECT/CT lymphoscintigraphy using Tc-nanocolloid.
• Intraoperative verification was performed using a gamma-ray probe to identify 'hot spots' with radiotracer uptake.
• Hot spots were removed, followed by pelvic lymph node dissection; all resected nodes were pathologically examined.

Main Results:

• An average of 3 hot spots per patient were identified, predominantly located distally and caudally to the uretero-iliac crossing.
• SPECT/CT and gamma-probe detection yielded similar results in 36 of 38 patients.
• Metastases were found in lymph nodes without increased radiotracer uptake in 2 patients, and some hot spots were metastasis-free.

Conclusions:

• Radio-guided lymph node mapping is a feasible technique for MIBC.
• Preoperative SPECT/CT and intraoperative gamma-ray probe detection offer comparable efficacy in identifying relevant lymph nodes.