title: Hybrid small animal imaging system combining magnetic resonance imaging with fluorescence tomography using single photon avalanche diode detectors.
abstract: The high sensitivity of fluorescence imaging enables the detection of molecular processes in living organisms. However, diffuse light propagation in tissue prevents accurate recovery of tomographic information on fluorophore distribution for structures embedded deeper than 0.5 mm. Combining optical with magnetic resonance imaging (MRI) provides an accurate anatomical reference for fluorescence imaging data and thereby enables the correlation of molecular with high quality structural/functional information. We describe an integrated system for small animal imaging incorporating a noncontact fluorescence molecular tomography (FMT) system into an MRI detector. By adopting a free laser beam design geometrical constraints imposed by the use of optical fibers could be avoided allowing for flexible fluorescence excitation schemes. Photon detection based on a single-photon avalanche diode array enabled simultaneous FMT/MRI measurements without interference between modalities. In vitro characterization revealed good spatial accuracy of FMT data and accurate quantification of dye concentrations. Feasibility of FMT/MRI was demonstrated in vivo by simultaneous assessment of protease activity and tumor morphology in murine colon cancer xenografts.
authors.affiliation: Institute for Biomedical Engineering, University and ETH Zurich, Zurich, Switzerland. stuker@biomed.ee.ethz.ch
authors.forename: Florian
authors.initials: F
authors.lastname: Stuker
authors.forename: Christof
authors.initials: C
authors.lastname: Baltes
authors.forename: Katerina
authors.initials: K
authors.lastname: Dikaiou
authors.forename: Divya
authors.initials: D
authors.lastname: Vats
authors.forename: Lucio
authors.initials: L
authors.lastname: Carrara
authors.forename: Edoardo
authors.initials: E
authors.lastname: Charbon
authors.forename: Jorge
authors.initials: J
authors.lastname: Ripoll
authors.forename: Markus
authors.initials: M
authors.lastname: Rudin
mesh_terms: D000818:Animals; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008279:Magnetic Resonance Imaging / Q000295:instrumentation* / Q000662:veterinary*; D051379:Mice; D008856:Microscopy, Fluorescence / Q000295:instrumentation* / Q000662:veterinary*; D008904:Miniaturization; D010783:Photometry / Q000295:instrumentation / Q000662:veterinary; D017785:Photons; D051381:Rats; D015203:Reproducibility of Results; D012666:Semiconductors; D012680:Sensitivity and Specificity; D013382:Subtraction Technique / Q000295:instrumentation* / Q000662:veterinary*; D041622:Tomography, Optical / Q000295:instrumentation / Q000662:veterinary; D014159:Transducers / Q000662:veterinary