Small Animal Imaging

Small animal research is a key translational link between fundamental research and clinical research. Animal models are utilized for essential preclinical in vivo information, such as sample dosage, for many biomedical therapies and devices prior to clinical acceptance.

When conducting preclinical in vivo studies, there are multiple imaging techniques to gather information. Optical imaging detection, over the UV to NIR wavelength range, has been commonly used within medical imaging, with each wavelength having their own advantages and limitations. UV and visible wavelengths can provide soft tissue information but are limited by penetration depth due to the high scattering of these wavelengths within tissue.

Near infrared (NIR) wavelengths are advantageous as they have reduced scattering within biological soft tissue and are thus used for preclinical in vivo studies. NIR can be separated into two distinct windows, with NIR-I encompassing wavelengths in the 750-1060 nm range, and NIR-II encompassing wavelengths in the 1060-1700 nm range. NIR-I wavelengths can be imaged via silicon CCDs but are only able to penetrate a few millimetres into soft tissue. NIR-II can penetrate deeper into tissue, due to reduced light scattering and autofluorescence, but can only be detected by InGaAs cameras. NIR-II methods have recently been developed for small animal imaging to investigate predominately early disease detection. Majority utilize fluorophores, such as single-walled carbon nanotubes and quantum dots, that fluoresce in the NIR-II region.