3D in vivo imaging of GFP-expressing T-cells in mice with non-contact fluorescence molecular tomography

Optical tomography has been proposed as a promising technique for probing deep in tissue with many medical applications. Recently, the adaptation of fluorescent probes by the radiologists, gave rise to a new imaging tool in the area of molecular imaging. Optical tomography can, provide three-dimensional images of fluorescent concentrations inside living systems of sizes in the order of many cm. Our optical tomographer was based on a technique which is called Fluorescence Molecular Tomography (FMT) and can quantify fluorescent signals in mice. The imaging procedure is performed in a non-contact geometry so that living subjects of arbitrary shapes can be imaged with no fibers attached to them. We have developed a way to reconstruct the 3D surface of the subject and we use theoretical models to account for the propagation of the emerging signal in the free space. The system consists of a rotating sample holder and a CCD camera in combination with a laser-scanning device. An Argon-ion laser is used as the source and different filters are used for the detection of various fluorophores or fluorescing proteins. So far, we have observed of the distribution of GFP expressing T-lymphocytes in-vivo for the study of the function of the immune system in a murine model. Then we investigated the performance of the FMT setup to quantify the different amounts of migrated cells in the different organs by comparing our results with the FACS measurements. Further experiments included the measurement of the variations of the T cell's concentration in-vivo, over time.