Optical imaging in pills: techniques, instruments and applications

Abstract

Optical imaging (OI) is an emerging field based on the detection of light photons in the ultraviolet, visible and infrared regions of the electromagnetic spectrum. According to the definition, the term “optical imaging” typically excludes classical microscopy techniques in favour of larger scale imaging methods which are devoted to the acquisition of images of small (few centimetres) sized samples. Biomedical OI is focused on the detection of biological samples with special attention to the in vivo acquisitions. Recent development of very sensitive detectors (photomultipliers and charge coupled devices – CCDs) allowed the detection of very weak light signal in biological samples not only in the visible range but also in the near infrared (NIR) region of the spectrum, which is noteworthy for the biological applications. The parallel advance of the light sources (lasers and LEDs) allowed to produce high intensity light beam with very powerful optical characteristics at relatively low costs. These two technological improvements, combined with the advances in the chemical field by the synthesis of new contrast agents with luminescent properties, led to the increasing importance of the OI techniques in the molecular imaging landscape. Here we review the conceptual bases of OI, the three main techniques (i.e. Bioluminescence, Fluorescence, and Cerenkov luminescence imaging), and some applications of OI in our laboratory.