James F. Baker, Presenter: Nothing to Disclose

Michael J Zhang, Abstract Co-Author: Nothing to Disclose

Chin Ng PhD, Abstract Co-Author: Nothing to Disclose

The purpose of this study was to evaluate the imaging parameters required for the accurate visualization and quantification of arteriogenesis to assess efficacy of novel therapeutics.

Three sets of mice with surgically induced ischemia of the right hindlimb were imaged on a small animal CT scanner set at 80kVp, 1800ms, 500μA, and 2X2 binning. The first set of samples were injected with Microfil, a silicone based contrast agent, prepared using manufacturer's instructions and then fixed with formalin. The second set of samples were prepared in the same manner as the first set, and then decalcified using Cal Ex II for 48 hours. The third set of samples were injected with a Microfil solution thats was prepared without using the dilutent recommended by the manufacturer and then decalcified using the same process as sample set two. The samples were then analyzed using the software Analyze 11.0 and segmented via thresholding. To verify the accuracy of volume measurements, a set of MicroCT phantoms were created using a iodine based gel and PEEK tubing. The tubing was filled with the iodine gel and then cut into various lengths. The phantoms were then scanned using the same parameters as the mouse hind limbs.

The first set of samples could not be accurately be segmented from the underlying bone due to the linear attenuation coefficient(LAC) of bone and Microfil being very similar resulting in similar intensities and an inability to accurately measure the vascular volume. Decalcification of the second set of samples created a greater separation in LAC of the vasculature and surrounding tissue. This allowed for an accurate segmentation of the vascular network and visualization of vessels larger than small arterioles. The lack of dilution in the third set of samples created a change in intensity of the small arterioles resulting in their visualization. The analysis of the MicroCT phantoms revealed that the volume of the phantoms could be estimated with an accuracy of 96.6±2.0%.

The results illustrate the ability to not only visually observe the growth and change in blood vessel number and size, but also that the volume of these changes can be measured accurately.

Peripheral arterial disease (PAD) represents a continuum of disease that range from asymptomatic PAD, intermittent claudication, critical limb ischemia, acute limb ischemia and amputation.

Baker, J, Zhang, M, Ng, C, Visualization and Volume Estimation of Mouse Hindlimb Arteriogenesis Using MicroCT Imaging.  Radiological Society of North America 2014 Scientific Assembly and Annual Meeting, - ,Chicago IL. http://archive.rsna.org/2014/14002881.html