title: Quantitative micro-CT based coronary artery profiling using interactive local thresholding and cylindrical coordinates.
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).
  
  
  CONCLUSIONS
  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.
authors.affiliation: CNR Institute of Clinical Physiology, Pisa, Italy.
authors.forename: Daniele
authors.initials: D
authors.lastname: Panetta
authors.affiliation: CNR Institute of Clinical Physiology, Pisa, Italy.
authors.forename: Gualtiero
authors.initials: G
authors.lastname: Pelosi
authors.affiliation: CNR Institute of Clinical Physiology, Pisa, Italy.
authors.forename: Federica
authors.initials: F
authors.lastname: Viglione
authors.affiliation: CNR Institute of Clinical Physiology, Pisa, Italy.
authors.forename: Claudia
authors.initials: C
authors.lastname: Kusmic
authors.affiliation: CNR Institute of Clinical Physiology, Pisa, Italy.
authors.forename: Marianna
authors.initials: M
authors.lastname: Terreni
authors.affiliation: Department of Physics ``E. Fermi'', University of Pisa, Pisa, Italy.
authors.forename: Nicola
authors.initials: N
authors.lastname: Belcari
authors.affiliation: Department of Physics ``E. Fermi'', University of Pisa, Pisa, Italy.
authors.forename: Alberto Del
authors.initials: AD
authors.lastname: Guerra
authors.affiliation: FORTH, Department of Biomedical Research, Institute of Molecular Biology and Biotechnology, Ioannina, Greece.
authors.forename: Lambros
authors.initials: L
authors.lastname: Athanasiou
authors.affiliation: FORTH, Department of Biomedical Research, Institute of Molecular Biology and Biotechnology, Ioannina, Greece.
authors.forename: Themistoklis
authors.initials: T
authors.lastname: Exarchos
authors.affiliation: FORTH, Department of Biomedical Research, Institute of Molecular Biology and Biotechnology, Ioannina, Greece.
authors.forename: Dimitrios I
authors.initials: DI
authors.lastname: Fotiadis
authors.affiliation: University of Kragujevac, Kragujevac, Serbia.
authors.forename: Nenad
authors.initials: N
authors.lastname: Filipovic
authors.affiliation: CNR Institute of Clinical Physiology, Pisa, Italy.
authors.forename: Maria Giovanna
authors.initials: MG
authors.lastname: Trivella
authors.affiliation: CNR Institute of Clinical Physiology, Pisa, Italy.
authors.forename: Piero A
authors.initials: PA
authors.lastname: Salvadori
authors.affiliation: CNR Institute of Clinical Physiology, Pisa, Italy.
authors.forename: Oberdan
authors.initials: O
authors.lastname: Parodi
mesh_terms: D000818:Animals; D003324:Coronary Artery Disease / Q000175:diagnosis* / Q000000981:diagnostic imaging* / Q000473:pathology; D003331:Coronary Vessels / Q000000981:diagnostic imaging*; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D058226:Plaque, Atherosclerotic / Q000000981:diagnostic imaging / Q000473:pathology; D013552:Swine; D055114:X-Ray Microtomography / Q000379:methods*
keywords: Micro-CT; artery segmentation; cylindrical coordinates; experimental atherosclerosis; histomorphometry