title: Validation of in vivo fluorochrome concentrations measured using fluorescence molecular tomography.
abstract: Fluorescence molecular tomography (FMT) has emerged as a means of quantitatively imaging fluorescent molecular probes in three dimensions in living systems. To assess the accuracy of FMT in vivo, translucent plastic tubes containing a turbid solution with a known concentration of Cy 5.5 fluorescent dye are constructed and implanted subcutaneously in nude mice, simulating the presence of a tumor accumulating a fluorescent molecular reporter. Comparisons between measurements of fluorescent tubes made before and after implantation demonstrate that the accuracy of FMT reported for homogeneous phantoms extends to the in vivo situation. The sensitivity of FMT to background fluorescence is tested by imaging fluorescent tubes in mice injected with Cy 5.5-labeled Annexin V. For small tube fluorochrome concentrations, the presence of background fluorescence results in increases in the reconstructed concentration. This phenomenon is counteracted by applying a simple subtraction correction to the measured fluorescence data. The effects of varying tumor photon absorption are simulated by imaging fluorescent tubes with varying ink concentrations, and are found to be minor. These findings demonstrate the in vivo quantitative accuracy of fluorescence tomography, and encourage further development of this imaging modality as well as application of FMT in molecular imaging studies using fluorescent reporters.
authors.affiliation: Stanford University School of Medicine, Department of Radiation Oncology, Stanford, California 94305, USA. egraves@stanford.edu
authors.forename: Edward E
authors.initials: EE
authors.lastname: Graves
authors.forename: Doreen
authors.initials: D
authors.lastname: Yessayan
authors.forename: Gordon
authors.initials: G
authors.lastname: Turner
authors.forename: Ralph
authors.initials: R
authors.lastname: Weissleder
authors.forename: Vasilis
authors.initials: V
authors.lastname: Ntziachristos
mesh_terms: D000465:Algorithms; D000818:Animals; D005456:Fluorescent Dyes / Q000032:analysis*; D007089:Image Enhancement / Q000379:methods; D007090:Image Interpretation, Computer-Assisted / Q000379:methods*; D021621:Imaging, Three-Dimensional / Q000379:methods*; D051379:Mice; D008819:Mice, Nude; D008856:Microscopy, Fluorescence / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013050:Spectrometry, Fluorescence / Q000379:methods*; D041622:Tomography, Optical / Q000379:methods*
chemical_list: D005456:Fluorescent Dyes