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Contrast Media & Molecular Imaging
Volume 2017, Article ID 7368384, 10 pages
https://doi.org/10.1155/2017/7368384
Research Article

Erbium-Based Perfusion Contrast Agent for Small-Animal Microvessel Imaging

1Imaging Research Laboratories, Robarts Research Institute, Western University, London, ON, Canada N6A 5B7
2Department of Medical Biophysics, Western University, London, ON, Canada N6A 5C1
3Department of Medical Imaging, Western University, London, ON, Canada N6A 5B7
4Department of Surgery, Western University, London, ON, Canada N6A 5B7

Correspondence should be addressed to Justin J. Tse; moc.liamg@pjj.est and David W. Holdsworth; ac.strabor@htrowsdlohd

Received 11 July 2017; Revised 11 September 2017; Accepted 2 October 2017; Published 15 November 2017

Academic Editor: Pedro Moreno Pimentel-Coelho

Copyright © 2017 Justin J. Tse et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Micro-computed tomography (micro-CT) facilitates the visualization and quantification of contrast-enhanced microvessels within intact tissue specimens, but conventional preclinical vascular contrast agents may be inadequate near dense tissue (such as bone). Typical lead-based contrast agents do not exhibit optimal X-ray absorption properties when used with X-ray tube potentials below 90 kilo-electron volts (keV). We have developed a high-atomic number lanthanide (erbium) contrast agent, with a K-edge at 57.5 keV. This approach optimizes X-ray absorption in the output spectral band of conventional microfocal spot X-ray tubes. Erbium oxide nanoparticles (nominal diameter < 50 nm) suspended in a two-part silicone elastomer produce a perfusable fluid with viscosity of 19.2 mPa-s. Ultrasonic cavitation was used to reduce aggregate sizes to <70 nm. Postmortem intact mice were perfused to investigate the efficacy of contrast agent. The observed vessel contrast was >4000 Hounsfield units, and perfusion of vessels < 10 m in diameter was demonstrated in kidney glomeruli. The described new contrast agent facilitated the visualization and quantification of vessel density and microarchitecture, even adjacent to dense bone. Erbium’s K-edge makes this contrast agent ideally suited for both single- and dual-energy micro-CT, expanding potential preclinical research applications in models of musculoskeletal, oncological, cardiovascular, and neurovascular diseases.