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Looking and listening to light: the evolution of whole-body photonic imaging


Optical imaging of live animals has grown into an important tool in biomedical research as advances in photonic technology and reporter strategies have led to widespread exploration of biological processes in vivo. Although much attention has been paid to microscopy, macroscopic imaging has allowed small-animal imaging with larger fields of view (from several millimeters to several centimeters depending on implementation). Photographic methods have been the mainstay for fluorescence and bioluminescence macroscopy in whole animals, but emphasis is shifting to photonic methods that use tomographic principles to noninvasively image optical contrast at depths of several millimeters to centimeters with high sensitivity and sub-millimeter to millimeter resolution. Recent theoretical and instrumentation advances allow the use of large data sets and multiple projections and offer practical systems for quantitative, three-dimensional whole-body images. For photonic imaging to fully realize its potential, however, further progress will be needed in refining optical inversion methods and data acquisition techniques.

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V.N. is supported in part by National Institutes of Health (NIH) grants RO1 EB 000750-1, 1-NO1-CO027105 and R33 CA 91807. J. Ripoll acknowledges support from EU Integrated Project “Molecular Imaging” LSHG-CT-2003-503259. R.W. is supported in part by NIH grants P50 CA86355, R24 CA92782, R33 CA091807, PO1 AI054904, PO1 CA69246 and grants from the Donald W. Reynolds Foundation and Siemens Medical Systems.

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Correspondence to Vasilis Ntziachristos.

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Figure 1: Modes of data collection.
Figure 2: Spectral imaging applied to in vivo fluorescence detection.
Figure 3: Fluorescence reconstruction of a fluorescent tube inserted in a euthanized animal obtained in the absence of contact detection.
Figure 4: In vivo fluorescence imaging.
Figure 5: Visualization of brain structure and function using photoacoustic tomography (modified from ref. 57.
Figure 6: Performance of planar and tomographic imaging.