Full-field time domain optical molecular imaging system

Abstract

The advent of optical molecular probes has taken optical imaging beyond approaches limited to intrinsic optical contrast mechanisms. Fluorophores are typically used as the source of contrast for optical molecular probes and the field of optical molecular imaging is concerned with measuring and quantifying their in vivo biodistribution and pharmacokinetics. Most optical molecular imaging systems are based on Continuous Wave (CW) approaches which enable rapid, full-body imaging of small animals and readily yield images of probe location, however quantification of probe concentration is challenging. Time Domain (TD) approaches, although more expensive and complicated than CW, provide more information to assist in determining the probe location and concentration. Moreover, the TD approach permits access to measuring the fluorophore lifetime which can be indicative of the probe’s environment. Existing TD approaches involve a point source and detector which are sequentially scanned over the sample and can take several minutes to acquire the data compared to the rapid imaging offered by CW. The system presented here employs a high power, near infrared, pulsed laser to provide area illumination and a temporally gated intensified CCD camera to permit area detection in order to enable rapid, full-body, TD optical molecular imaging of small animals in vivo. The system is described and preliminary in vitro and in vivo measurements are presented.