Contrast enhanced small animal vessel imaging by microCT is a rapid, cost-effective and high-throughput technique for serial in situ examination for tumor development, for analyzing the network of blood vessels that nourish them, and for following the response of tumors to preclinical therapeutic intervention(s).
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Method Article
Contrast Enhanced Vessel Imaging using MicroCT
In This Article
Summary
Abstract
Microscopic computed tomography (microCT) offers high-resolution volumetric imaging of the anatomy of living small animals. However, the contrast between different soft tissues and body fluids is inherently poor in micro-CT images 1. Under these circumstances, visualization of blood vessels becomes a nearly impossible task. To overcome this and to improve the visualization of blood vessels exogenous contrast agents can be used. Herein, we present a methodology for visualizing the vascular network in a rodent model. By using a long-acting aqueous colloidal polydisperse iodinated blood-pool contrast agent, eXIA 160XL, we optimized image acquisition parameters and volume-rendering techniques for finding blood vessels in live animals. Our findings suggest that, to achieve a superior contrast between bone and soft tissue from vessel, multiple-frames (at least 5-8/ frames per view), and 360-720 views (for a full 360° rotation) acquisitions were mandatory. We have also demonstrated the use of a two-dimensional transfer function (where voxel color and opacity was assigned in proportion to CT value and gradient magnitude), in visualizing the anatomy and highlighting the structure of interest, the blood vessel network. This promising work lays a foundation for the qualitative and quantitative assessment of anti-angiogenesis preclinical studies using transgenic or xenograft tumor-bearing mice.
Protocol
1. Animal Injections
Prior to intravenous tail vein injection, the tail skin should be cleaned with isopropyl alcohol scrubs for sterilization purposes. Mice should then be injected with 0.2 mL/20 g of a 20-mg iodine/mL iodinated bloodpool contrast agent (eXIA 160XL; Binito Biomedical, Inc. Ottawa, ON, Canada) via the distal tail vein using low dead space ½ CC U-100 28G½ Insulin Syringes (Product #329461, Becton Dickinson and company, NJ, USA).
2. Animal Preparation
After 10 minutes of injection, the animals should be prepared for microCT imaging. First, the animal should be anesth....
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Discussion
The foremost goal of this technique of contrast enhanced vessel imaging using microCT is to provide optimal method for generating high quality datasets for analysis of vascular networks in live mice. For microCT imaging, better signal-to-noise ratio of soft tissue is achieved by longer scan times with increased numbers of views and number of frames per view 2.
Vessel identification is critically dependent upon accurate soft tissue identification and differentiation from bone. eXIA .......
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Disclosures
All animal procedures were conducted in accordance with the Guidelines for the Care and Use of Laboratory Animals and were approved by the Institutional Animal Care and Use Committee (IACUC) at the University of Texas Health Science Center at San Antonio.
Acknowledgements
This work was supported in part by NCI award 5R01CA133229-03.
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Materials
| Name | Company | Catalog Number | Comments |
|---|---|---|---|
| eXIA 160XL | Binito Biomedical, Inc. | eXIA160XL-01 |
References
- Holdsworth, D. W., Thornton, M. M. Micro-CT in small animal and specimen imaging. Trends in Biotechnology. 20, 417-424 (2002).
- Kindlmann, G. L., Weinstein, D. M., Jones, G. M., Johnson, C. R., Capecchi, M. R., Keller, C. Practical Vessel Imaging by Computed To....
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