Affiliations: [a] CNR Institute of Clinical Physiology, Pisa, Italy | [b] Department of Physics ``E. Fermi'', University of Pisa, Pisa, Italy | [c] FORTH, Department of Biomedical Research, Institute of Molecular Biology and Biotechnology, Ioannina, Greece | [d] University of Kragujevac, Kragujevac, Serbia
Correspondence:
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Corresponding author: Daniele Panetta, Laboratory of Imaging Biomarkers, CNR Institute of Clinical Physiology, Via G. Moruzzi, 1, I-56124 Pisa, Italy. E-mail:daniele.panetta@ifc.cnr.it
Abstract: BACKGROUND: Micro-CT is an established imaging technique for
high-resolution non-destructive assessment of vascular samples, which is
gaining growing interest for investigations of atherosclerotic arteries both
in humans and in animal models. However, there is still a lack in the
definition of micro-CT image metrics suitable for comprehensive evaluation
and quantification of features of interest in the field of experimental
atherosclerosis (ATS).
OBJECTIVE: A novel approach to micro-CT image processing for
profiling of coronary ATS is described, providing comprehensive
visualization and quantification of contrast agent-free 3D high-resolution
reconstruction of full-length artery walls.
METHODS: Accelerated coronary ATS has been induced by high fat cholesterol-enriched diet in swine and left coronary artery (LCA) harvested en bloc
for micro-CT scanning and histologic processing. A cylindrical coordinate
system has been defined on the image space after curved multiplanar
reformation of the coronary vessel for the comprehensive visualization of
the main vessel features such as wall thickening and calcium content. A
novel semi-automatic segmentation procedure based on 2D histograms has been
implemented and the quantitative results validated by histology.
RESULTS: The potentiality of attenuation-based micro-CT at low kV
to reliably separate arterial wall layers from adjacent tissue as well as
identify wall and plaque contours and major tissue components has been
validated by histology. Morphometric indexes from histological data
corresponding to several micro-CT slices have been derived (double observer
evaluation at different coronary ATS stages) and highly significant
correlations (R2 > 0.90) evidenced. Semi-automatic morphometry has
been validated by double observer manual morphometry of micro-CT slices and
highly significant correlations were found (R2 > 0.92).
CONCLUSION: The micro-CT methodology described represents a handy
and reliable tool for quantitative high resolution and contrast agent free full
length coronary wall profiling, able to assist atherosclerotic vessels
morphometry in a preclinical experimental model of coronary ATS and
providing a link between in vivo imaging and histology.
