Characterization of sub-resolution microcirculatory status using whole-body CT imaging

Yue Dong, Nasser M. Malyar, Patricia E. Beighley, Erik L. Ritman

Research output: Contribution to journalConference article

2 Scopus citations

Abstract

Myocardial microcirculation disturbances often precede angiographically visible of narrowing large epicardial coronary uleries and associated symptoms. Clinical tomographic imaging cannot resolve the microcirculation, hence an indirect method of quantitating microvascular disturbances in those images must be developed. We propose that such an indirect method can be based on the characterization of the spatial heterogeneity of myocardial intravascular blood volume. We evaluated the relationship of multi-resolution, nested multi Region-of-Interest (ROI) analysis of EBCT images to the actual intravascular volume of microvascular branches as measured directly with micro-CT images in the same myocardial regions. We selectively altered the intravascular volume of vessels by injecting 30, 100, 200 or 300μm diameter microspheres into anesthetized pigs' LAD coronary arteries prior to EBCT scanning during contrast injection. The heart was then harvested and the LAD coronary artery was infused with Microfil polymer. An approximately 2cm3 transmural "biopsy" of the same ROI within the myocardium analyzed in the EBCT images was scanned by micro-CT resulting in a 3D image of 20μm cubic voxels. Myocardial opacification was measured in both the EBCT and micro-CT images. The EBCT and micro-CT images were analyzed with the nested multi ROI method which provides an index of spatial heterogeneity of intramyocardial blood volume in terms of the linear relationship between the logarithms of the coefficient of variation within the data obtained at any one size of the ROI, and the logarithm of the volume of that selected ROI. The minimum ROI volume in the EBCT analysis was 8.96 mm3 and for the micro-CT it was 0.07 mm3. There is linear correlation when EBCT and micro-CT image CT gray-scale numbers are plotted as Log (standard deviation/mean) against Log (Volume of ROI). The results show that the slopes and offsets of the EBCT-based and micro-CT-based regression lines were indistinguishable. Moreover, when a fraction of micro vessels of selected diameter was embolized, the change in the resulting regression line was characteristic for that diameter. In summary, the EBCT-based analysis spatial heterogeneity of myocardial blood volume can be extrapolated to describe the spatial distribution of the microcirculatory branching geometry in terms of ultra segmental lumen volume.

Original languageEnglish (US)
Article number22
Pages (from-to)175-183
Number of pages9
JournalProgress in Biomedical Optics and Imaging - Proceedings of SPIE
Volume5746
Issue numberI
DOIs
StatePublished - Aug 25 2005
EventMedical Imaging 2005 - Physiology, Function, and Structure from Medical Images - San Diego, CA, United States
Duration: Feb 13 2005Feb 15 2005

Keywords

  • Blood volume
  • EBCT
  • Heterogeneity
  • Micro-CT
  • Microcirculation
  • Myocardium
  • Subresolution

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Biomaterials
  • Atomic and Molecular Physics, and Optics
  • Radiology Nuclear Medicine and imaging

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