NEAR INFRARED FLUORESCENCE IMAGING
Detection of fluorescence signal in deeper tissues
Optical imaging using near-infrared fluorescence (NIR) light is a new imaging modality that has recently emerged in the field of cancer imaging. This technique promises high sensitivity and can be used to image a wide variety of molecular entities in vivo, through the promise of versatile fluorescent probe design. The use of near-infrared wavelengths for imaging permits relatively deep photon penetration into tissue, minimal tissue autofluorescence, less scatter, and higher optical contrast when exogenous NIR fluorophores are introduced. It is of great importance for translational research as future cancer surgery relies on optical imaging during surgery. Larger depth can be probed in the far red or near infrared spectral region as the absorption is as at least one order of magnitude lower than in the visible range. NIR light (700 –1000 nm wavelength) can penetrate several centimeters into tissue. In far red and NIR imaging autofluorescence is much lower because tissues do not autofluoresce under longer wavelength light.
In most applications, NIR optical imaging is used in concert with molecularly targeted fluorescent contrast agents that not only provide enhanced contrast but also, more importantly, reveal specific molecular events associated with cancer formation and progression. In vivo fluorescence imaging with near‐infrared light holds enormous potential for a wide variety of molecular diagnostic and therapeutic applications.
Multilabel overlay of NIR fluorescent and bioluminescent signal
Nude mouse with intracardiac injection of PC3 cells (prostate cancer). IV injection of 9 nmol IR780 (0,2mg/kg). Imaging 24h post injection – signal in the heart. Multilabeling: Overlay of fluorescent and bioluminescent signal. A metastasis can be seen in the intestines on the left side of the mouse.
Courtesy of UROLEAD, France