Multispectral Fluorescence Imaging as a Tool to Distinguish Pelvic Lymphatic Drainage Patterns During Robot-assisted Lymph Node Dissection in Prostate Cancer.

backgroundThe invasive nature of extended pelvic lymph node dissection (ePLND) prompts the need for alternative lymphatic mapping technologies. To change the focus to "sparing nodes that are not involved," the first step is to research the feasibility of intraoperatively distinguishing the lymph drainage patterns of the prostate from healthy organs.

methodsWe performed a prospective study (NCT05120973) that included 16 patients who underwent a robot-assisted radical prostatectomy + ePLND + sentinel node (using indocyanine green-

resultsIndocyanine green and fluorescein were visible in the same regions within the ePLND-template and co-accumulated in lymph vessels in vivo. At histopathology, fluorescein was seen in only 10 of 370 lymph nodes (possibly owing to tracer properties), none of which overlapped with indocyanine green and none were tumor-positive. Administration of fluorescein did not result in discomfort or abnormal postoperative recovery.

conclusionsMultispectral imaging can be used to distinguish lymphatic drainage patterns. Our in vivo findings indicate that within the ePLND-template, lymphatic drainage patterns of the prostate at least partly overlap with those of upper leg and abdominal wall. The properties of fluorescein render it unsuitable for confirmation of fluorescence at histopathology.