Abstract:
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Purpose: Near-infrared fluorescence Optical Imaging (OI) enhanced with indocyanine green (ICG) was used to compare the pharmacokinetic response of the signal intensity of tumor and soft tissue in a model of human breast cancer implanted in athymic rats
Methods and Materials: The imaging system incorporated an OPO laser tunable from 660 to 970nm, emitting laser light transferred in the imaging compartment of the system via a fiber, used to photo-excite the tissue. A liquid nitrogen-cooled CCD camera was used to capture the images. Filters were positioned at the output of the illumination fiber to ensure monochromatic illumination of the imaged tissue at 780nm, and in front of the CCD camera to select the appropriate spectral window at 850nm corresponding to the fluorescence emission band of ICG. A laptop computer remotely operated the system. Rats were anesthetized using isoflurane and placed on a trough with the tumor facing the exciting laser and the reception CCD camera. ICG was injected as a bolus in the tail vein at a dose of 300 ml/kg in 5 rats bearing MDA-MB-231 human breast cancer xenografts varying from 1.0 to 1.5 cm diameter. Signal response was measured dynamically from one hour to four days post-injection in the tumor, the adjacent normal soft tissue, and was normalized to an external phantom emitting a constant fluorescent signal.
Results: Tumors enhanced to a maximum of 80% above baseline between 12 and 24 hours after injection of ICG, persisting at four days. In normal adjacent soft tissue, enhancement reached a maximum of 58% earlier, at 12 hours, returning to baseline also earlier than the tumor, at 36/48 hours after injection. The tumor-to-normal tissue signal intensity ratio, was consistently elevated, yielding tumor-to-tissue contrast, ranging from 1.6 to 4.2. The peak ratio occurred at 24 hours post-injection, when the tumors were at their peak enhancement, whereas the normal tissue enhancement was already declining. Contrast injection also allowed the definition of fine tumor blood vessels.
Conclusion: These results support the potential application of dynamic contrast-enhanced near-infrared optical imaging for the identification and characterization of breast-cancer in a clinical setting.
Lucidi MD, V,
Near-Infrared Fluorescence Optical Imaging Using Indocyanine Green in an Animal Model of Human Breast Cancer. Radiological Society of North America 2003 Scientific Assembly and Annual Meeting, November 30 - December 5, 2003 ,Chicago IL.
http://archive.rsna.org/2003/3108222.html
