Non-enhanced micro-CT of paraffin embedded coronary vessels: a tool for experimental atherosclerosis

Purpose. To assess and quantify morphometric parameters of full-length coronary arteries in three dimensions at high resolution by micro-CT (?CT), and to evaluate the possible integration with in vivo information by invasive coronary angiography (ICA) and and intravascular ultrasound (IVUS). Methods and Materials. Excised left coronary artery (LMCA and LAD) and underlying myocardium from pigs on a high-cholesterol diet were fixed in formalin, dehydrated and embedded in paraffin as a whole sample inside a Falcon-type test tube. In vivo information obtained by ICA and IVUS were also available for the same animals. After the ?CT scan, the samples were further processed in order to perform standard histological stains. Results. For each sample, we have obtained a reconstructed volume of 512x512x1400 isotropic voxels, with a voxel size of 57.4^3 ?m^3. The ?CT images provided good discrimination between fat, muscle and calcium, allowing a reliable segmentation of walls and lesions. The profiles of total area, wall area and calcium along the entire coronary artery allowed a comprehensive evaluation of the progress of atherosclerosis in terms of intimal thickening, plaque formation and calcification. Microcalcifications down to 0.2 nl (nanoliters) were localized and displayed in 3D. The integration with IVUS allowed also to recover the lumen area under in vivo physiological state. Conclusion. Micro-CT allows a comprehensive evaluation in 3D and at high resolution of plaque evolution in an experimental model of coronary artery disease in pigs. The integration with ICA and IVUS can lead to the full characterization of disease progression