Sentinel Lymph Node Mapping of Invasive Urinary Bladder Cancer in Animal Models Using Invisible Light

Abstract

Objectives-With conventional methodology, sentinel lymph node (SLN) mapping of invasive urinary bladder cancer is technically challenging. This study was performed to determine the utility of invisible, near-infrared fluorescent (NIRF) light for patient-specific SLN mapping, in real time under complete image guidance.Methods-Lymphatic tracers, injection volume, NIRF excitation fluence rate, light collection of emitted fluorescence, and degree of bladder distension were systematically optimized in normal dogs and pigs. SLN mapping was then performed in pet dogs with naturally occurring invasive transitional cell carcinoma (InvTCC) of the urinary bladder, which closely mimics the human disease.Results-NIRF albumin (hydrodynamic diameter [HD], 7.4 nm) and NIRF quantum dots (15-20 nm HD) injected into the bladder wall resulted in identification of draining lymph nodes (LNs) in under 3 min. In both species, considerable variability in the lymphatic drainage was observed among individuals. Optimal SLN mapping was achieved with the use of superficial, serosal injection of NIRF tracer, with the bladder distended to an intraluminal pressure of 20-40 cm H 2 O. In dogs with InvTCC, NIRF tracers identified SLNs that were confirmed histologically to harbor metastases.Conclusions-The use of invisible NIRF light permits real-time, patient-specific identification of SLNs that drain bladder cancer. Intraluminal bladder pressure is a key parameter that needs to be controlled for optimal results. KeywordsBladder cancer; Fluorescence; Intraoperative imaging; Sentinel lymph node mapping * Corresponding author. Purdue University, Department of Veterinary Clinical Sciences, Lynn Hall of Veterinary Medicine, 625 Harrison St, West Lafayette, IN 47907-2026. Tel.765-494-9900; Fax: 765-496-1108. E-mail address: knappd@purdue.edu (D.W. Knapp). Take-home message This article describes successful use of intraoperative near-infrared light to identify sentinel lymph nodes (SLNs) draining invasive urinary bladder cancer in animals. This technology will permit studies of a new approach to identify SLNs at the time of cystectomy.Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers

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