Sentinel lymph node mapping of invasive urinary bladder cancer in animal models using invisible light.
OBJECTIVE
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.
Knapp
Deborah W
DW
Department of Veterinary Clinical Sciences, and Purdue Cancer Center and Oncological Sciences Center, West Lafayette, IN 47907, USA. knappd@purdue.edu
Adams
Larry G
LG
Degrand
Alec M
AM
Niles
Jacqueline D
JD
Ramos-Vara
José A
JA
Weil
Ann B
AB
O'Donnell
Michael A
MA
Lucroy
Michael D
MD
Frangioni
John V
JV
D000818:Animals; D002295:Carcinoma, Transitional Cell / Q000473:pathology; D004195:Disease Models, Animal; D004285:Dogs; D005260:Female; D008297:Male; D009361:Neoplasm Invasiveness; D021701:Sentinel Lymph Node Biopsy; D013552:Swine; D001749:Urinary Bladder Neoplasms / Q000473:pathology*