Hybrid Small Animal Imaging System Combining Magnetic Resonance Imaging With Fluorescence Tomography Using Single Photon Avalanche Diode Detectors

• Published in: IEEE transactions on medical imaging Vol. 30; no. 6; pp. 1265 - 1273
• Main Authors: Stuker, F, Baltes, C, Dikaiou, K, Vats, D, Carrara, L, Charbon, E, Ripoll, J, Rudin, M
• Format: Journal Article
• Language: English
• Published: United States IEEE 01.06.2011; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Animals; Biomedical imaging; Detectors; Equipment Design; Equipment Failure Analysis; Laser beams; Magnetic resonance imaging; magnetic resonance imaging (MRI); Magnetic Resonance Imaging - instrumentation; Magnetic Resonance Imaging - veterinary; Medical imaging; Mice; Microscopy, Fluorescence - instrumentation; Microscopy, Fluorescence - veterinary; Miniaturization; Optical imaging; Optical surface waves; optical tomography; Phantoms; Photometry - instrumentation; Photometry - veterinary; Photons; Rats; Reproducibility of Results; Semiconductors; Sensitivity and Specificity; Subtraction Technique - instrumentation; Subtraction Technique - veterinary; Tomography, Optical - instrumentation; Tomography, Optical - veterinary; Transducers - veterinary
• ISSN: 0278-0062; 1558-254X
• DOI: 10.1109/TMI.2011.2112669

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.