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Journal of Photochemistry and Photobiology B: Biology 98 (2010) 77–94

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Journal of Photochemistry and Photobiology B: Biology
journal homepage: www.elsevier.com/locate/jphotobiol

Pre-clinical whole-body fluorescence imaging: Review of instruments, methods and applications
Frederic Leblond a,*, Scott C. Davis a, Pablo A. Valdés a, Brian W. Poguea,b
a b

Thayer School of Engineering, Dartmouth College, Hanover NH 03755, USA Department of Surgery, Dartmouth Medical School, Lebanon, NH 03756, USA

a r t i c l e

i n f o

a b s t r a c t
Fluorescence sampling of cellular function is widely used in all aspects of biology, allowing the visualization of cellular and sub-cellular biological processes with spatial resolutions in the rangefrom nanometers up to centimeters. Imaging of fluorescence in vivo has become the most commonly used radiological tool in all pre-clinical work. In the last decade, full-body pre-clinical imaging systems have emerged with a wide range of utilities and niche application areas. The range of fluorescent probes that can be excited in the visible to near-infrared part of the electromagnetic spectrumcontinues to expand, with the most value for in vivo use being beyond the 630 nm wavelength, because the absorption of light sharply decreases. Whole-body in vivo fluorescence imaging has not yet reached a state of maturity that allows its routine use in the scope of large-scale pre-clinical studies. This is in part due to an incomplete understanding of what the actual fundamental capabilities andlimitations of this imaging modality are. However, progress is continuously being made in research laboratories pushing the limits of the approach to consistently improve its performance in terms of spatial resolution, sensitivity and quantification. This paper reviews this imaging technology with a particular emphasis on its potential uses and limitations, the required instrumentation, and thepossible imaging geometries and applications. A detailed account of the main commercially available systems is provided as well as some perspective relating to the future of the technology development. Although the vast majority of applications of in vivo small animal imaging are based on epi-illumination planar imaging, the future success of the method relies heavily on the design of novel imagingsystems based on state-of-the-art optical technology used in conjunction with high spatial resolution structural modalities such as MRI, CT or ultrasound. Published by Elsevier B.V.

Article history: Received 22 July 2009 Received in revised form 16 November 2009 Accepted 20 November 2009 Available online 26 November 2009 Keywords: Fluorescence Imaging Tomography Commercial Small animal Diagnostic1. Introduction Many researchers in the biological sciences appreciate the extraordinary contrast and specificity provided by fluorescence microscopy. Extrapolating this imaging paradigm to whole-body animal imaging is enticing. However, the physical realities associated with imaging in live tissue make this a continuously elusive objective, as will be evidenced in this review paper. Nevertheless,the information derived from in vivo fluorescence imaging systems can be regarded as an important complement to microscopy studies performed on cell cultures and tissue slices because it provides information about specific biological processes in fully integrated living systems1. Fig. 1 illustrates the salient differences between in vitro, ex vivo and in vivo fluorescence from biologicalapplications relating to brain imaging. Though in essence the underlying techno-

* Corresponding author. Tel.: +1 603 646 2100; fax: +1 603 646 3856. E-mail address: frederic.leblond@dartmouth.edu (F. Leblond). 1 In this paper the term in vivo is used in relation with studies performed using live animals, i.e., excluding work done with live cells in cultures (see Fig. 1). 1011-1344/$ - see front matter...