Intraoperative Fluorescence Imaging for Detection of Sentinel Lymph Nodes and Lymphatic Vessels during Open Prostatectomy using Indocyanine Green

We investigated the feasibility and validity of intraoperative fluorescence imaging using indocyanine green for the detection of sentinel lymph nodes and lymphatic vessels during open prostatectomy.

Indocyanine green was injected into the prostate under transrectal ultrasound guidance just before surgery. Intraoperative fluorescence imaging was performed using a near-infrared camera system in 66 consecutive patients with clinically localized prostate cancer after a 10-patient pilot test to optimize indocyanine green dosing, observation timing and injection method. Lymphatic vessels were visualized and followed to identify the sentinel lymph nodes. Confirmatory pelvic lymph node dissection including all fluorescent nodes and open radical prostatectomy were performed in all patients.

Lymphatic vessels were successfully visualized in 65 patients (98%) and sentinel lymph nodes in 64 patients (97%). Sentinel lymph nodes were located in the obturator fossa, internal and external iliac regions, and rarely in the common iliac and presacral regions. A median of 4 sentinel lymph nodes per patient was detected. Three lymphatic pathways, the paravesical, internal and lateral routes, were identified. Pathological examination revealed metastases to 9 sentinel lymph nodes in 6 patients (9%). All pathologically positive lymph nodes were detected as sentinel lymph nodes using this imaging. No adverse reactions due to the use of indocyanine green were observed.

Intraoperative fluorescence imaging using indocyanine green during open prostatectomy enables the detection of lymphatic vessels and sentinel lymph nodes with high sensitivity. This novel method is technically feasible, safe and easy to apply with minimal additional operative time.