Page 62 - Fluorescence-guided cancer surgery

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Chapter 4
invasive technique. This technical report is the rst to describe the use of ICG and laparoscopic NIR uorescence imaging to identify and resect melanoma liver metastasis during laparoscopic liver surgery.
METHODS
Intraoperative laparoscopic near-infrared imaging system
Intraoperative NIR uorescence imaging of the liver was performed using a newly developed laparoscopic high de nition (HD) uorescence imaging system by Karl Storz GmbH & Co. KG, Germany, which included a plasma light guide and a 30 degree angle, 10 mm laparoscope, applicable for white light ( WL), auto uorescence, and ICG-imaging. The system was used for intraoperative conventional imaging (WL mode) and real-time uorescence imaging (760 nm light, ICG mode) and allowed easy switching between WL mode and ICG mode by using a foot pedal. No overlay of conventional and uorescent images was possible yet, but anatomical orientation could be maintained due to the easy switching between light modes, the anatomical translucence during ICG mode and the stable position of the laparoscope. Images were recorded using a charge-coupled device camera.
Preparation and administration of indocyanine green
ICG (25 mg vials) was purchased from Pulsion Medical Systems (Munich, Germany) and resuspended in 10 cc of sterile water for injection to yield a 2.5 mg/ml (3.2 mM) stock solution. Of this stock solution 4 mL, corresponding to a dose of 10 mg, was administered intravenously 24 h before surgery. This optimal timing was based on previous studies in patients with colorectal liver metastases and the Mini-FLARE open quantitative imaging system.
Ex vivo imaging and uorescence microscopy of resected lesion
After slicing of the resected lesion at the Pathology department, uorescent imaging was performed with the FLARE imaging system, which was previously described14. Fluorescence microscopy images were obtained with the Odyssey Infrared Imaging System (LI-COR, USA).