Small Animal Imaging

In recent years, research groups around the world have been developing different methods to be utilized with the NIR-II / SWIR window in small-animal imaging for preclinical research, with an eye towards early detection of diseases (e.g., better early cancer detection techniques) for human patients. Most of these approaches are based on one of three primary technologies: single-walled carbon nanotubes (SWNTs), rare-earth–doped phosphors, or quantum dots.

The extension of in vivo optical imaging for disease screening and image-guided surgical interventions requires brightly emitting, tissue-specific materials that optically transmit through living tissue and can be imaged with portable systems that display data in real-time1. Work performed by a number of groups has begun to demonstrate that fluorescence imaging in the NIR-II / SWIR range can provide appreciably greater in vivo sensitivity compared to fluorescence imaging in the NIR-I region.

Additional details, as well as experimental data, can be found in “Deeply Cooled, Scientific InGaAs Cameras Facilitate NIR-II / SWIR Imaging for Drug Discovery / Small-Animal Research”.

1. Naczynski D.J., Tan M.-C., Zevon M., Wall, B., Kohl J., Kulesa A., Chen S., Roth C.M., Riman R.E., and Moghe P.V. Rare-earth–doped biological composites as in vivo shortwave infrared reporters. Nat. Commun. 4, (2013).

PI’s Picks:

For small-animal imaging in the NIR II / SWIR range, Princeton Instruments recommends the NIRvana:640 camera. We designed this 16-bit camera specifically for scientific research applications that require superb linearity and excellent near-infrared sensitivity. Its 640 x 512 InGaAs detection array, which delivers response from 0.9 μm to 1.7 μm, can be thermoelectrically cooled as low as -85°C in order to minimize thermally generated noise and improve signal-to-noise ratio.

Absorption graph - small animal imagingAbsorption chart. Courtesy of Dr. Dominik J. Naczynski, Stanford University, adapted from Smith, A.M. et al. Nat Nanotechnol. (2009) 4, 710.

Prof. Hongjie Dai at Stanford University has performed NIR-I as well as NIR-II / SWIR fluorescence imaging of blood vessels in mice using the setup illustrated below. Biocompatible SWNT-IRDye-800 conjugates were utilized as dual-color imaging agents, where IRDye-800 was a commercial NIR-I fluorophore and high-pressure carbon monoxide conversion SWNTs were stably suspended by biocompatible surfactants2.

Small animal imaging experimental set-up

(a) Upon excitation by a 785 nm laser, the SWNT-IRDye-800 conjugate emits at ~800 nm (NIR-I region) from the IRDye-800 dye and between 1100 and 1400 nm (NIR-II region) from the SWNT backbone. (b) Absorption spectrum of the SWNT–IRDye-800 conjugate (black dashed line), emission spectrum of the IRDye-800 dye (green line), and emission spectrum of the SWNTs (red line). (c) Imaging setup for simultaneous detection of both NIR-I and NIR-II / SWIR photons using silicon and InGaAs cameras, respectively. A zoomable lens set was used for adjustable magnifications. Schematics2 and spectra2 courtesy of Prof. Hongjie Dai, Stanford University. For more details, as well as images and data, refer to “Deeply Cooled, Scientific InGaAs Cameras Facilitate NIR-II / SWIR Imaging for Drug Discovery / Small-Animal Research”.
2. Hong G., Lee J.C., Robinson J.T., Raaz U., Xie L., Huang N.F., Cooke J.P., and Dai, H. Multifunctional in vivo vascular imaging using near-infrared II fluorescence. Nat. Med. 18, 1841–1846 (2012).

Publications

Brian W. Pogue
2015 
Molecular Imaging through centimeters of tissue: High resolution imaging with Cerenkov excitation
Frontiers in Optics 2015 Brian W. Pogue
... Luminescence was detected from the specimens by a gated intensified CCD camera (ICCD PI- MAX4, Princeton Instruments) with triggering from the LINAC output, gating the intensifier amplify only during the 3 us bursts of radiation, delivered at 200 Hz. ...
Fan Zhang, et al.
2017 
In vivo gastrointestinal drug-release monitoring through second near-infrared window fluorescent bioimaging with orally delivered microcarriers
Researchers at Fudan University, Shanghai, China utilized a NIRvana SWIR camera in their research on non-invasive tracking of gastrointestinal drug release using novel microcarriers by measuring fluorescence signals.
O. Bruns, T. Bischof, M. Bawendi, et al.
2017 
Next-generation in vivo optical imaging with short-wave infrared quantum dots
The NIRvana scientific SWIR camera was a key component of this in-vivo imaging research that utilized indium-arsenide-based quantum dots to allow imaging of several organs in live mice, including metabolic turnover rates of lipoproteins in organs and three-dimensional quantitative flow maps of the mouse brain vasculature.
J. Carr, M. Bawendi, O Bruns et al.
2017 
Shortwave Infrared Fluorescence Imaging with the Clinically Approved Near-Infrared Dye Indocyanine Green
Demonstration of in vivo optical SWIR fluorescence imaging techniques for in vivo angiography and tumor targeted imaging. Use of FDA approved dyes shows the suitability for human applications. Observation at SWIR wavelength leads to higher contrast images of structures located in several mm depth of tissue.

Application Notes

Deeply Cooled, Scientific InGaAs Cameras Facilitate NIR-II / SWIR Imaging for Drug Discovery / Small-Animal Research
The Utilization of Materials Such as SWNTs, Rare-earth–doped Phosphors, and Quantum Dots in Concert with Deeply Cooled, Scientific InGaAs Cameras Holds Great Promise for the Future of In Vivo Optical Iimaging Applications in the NIR-II / SWIR Range

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LightField Scientific Imaging & Spectroscopy Software

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Featured Product for Small Animal Imaging

NIRvana SWIR InGaAs Cameras

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Scientific grade, cooled InGaAs focal plane array cameras for demanding SWIR imaging and spectroscopy


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