Imaging of a Targeted PDT Drug with Fluorescence Tomography

We constructed a whole-body fluorescence tomography instrument to monitor novel bifunctional phototherapeutic drugs (e.g., HPPH-Cyanine dye conjugate) in small animals. The instrument allows dense source and detector sampling with a fast galvo scanner and a CCD detector for improved resolution and sensitivity (Patwardhan et al., 2005). Here we report tissue phantom measurements to evaluate the imaging performance with a newly constructed tomography instrument. Phantom measurements showed that strong fluorescence generated by HPPH-Cyanine dye (HPPH-CD), having high fluorescence quantum yield and long wavelength fluorescence emission, allowed deep tissue imaging. We also report in vivo fluorescence measurements of the conjugate in Nude mice bearing A549 human non-small cell lung carcinoma(NSCLC) tumors at 24 hr post injection to evaluate tumor detection ability of the conjugate. Our results indicate that the HPPH-CD shows preferential uptake in tumors compared to surrounding normal tissue at 24 hr post injection. This study demonstrates a potential use of HPPH-CD in detection (fluorescence imaging) and treatment (PDT) of deeply seated tumors.