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Updated: May 6, 2026
In Vivo Quantitative Assessment of Myocardial Structure, Function, Perfusion and Viability Using Cardiac Micro-computed Tomography
Published on: February 16, 2016
Early changes in myocardial microcirculation in asymptomatic hypercholesterolemic subjects: as detected by perfusion
Insights
Early atherosclerosis alters heart microcirculation function, detectable by CT perfusion scans. Hypercholesterolemia increases spatial heterogeneity in myocardial blood flow and volume before significant coronary artery stenosis develops.
Area of Science:
- Cardiovascular Imaging
- Atherosclerosis Research
- Medical Diagnostics
Background:
- Intramyocardial microvessels undergo functional changes in early atherosclerosis, preceding epicardial coronary artery stenosis.
- Clinical CT lacks the spatial resolution to directly visualize these microvessels.
- Detecting early microcirculatory dysfunction is crucial for timely intervention.
Purpose of the Study:
- To assess if myocardial perfusion CT can detect functional changes in intramyocardial microcirculation.
- To quantify spatial heterogeneity of myocardial perfusion (F) and blood volume (Bv) in at-risk individuals.
- To identify early signs of microcirculatory impairment in hypercholesterolemia.
Main Methods:
- Utilized perfusion CT to determine spatial heterogeneity of myocardial perfusion (F) and blood volume (Bv).
- Subdivided left ventricular myocardium into nested regions of interest (nROI) to compute F and Bv.
- Compared a control group (no CAD risk factors) with an at-risk group (hypercholesterolemia, no CAD).
Main Results:
- Overall myocardial F and Bv did not differ significantly between control and at-risk groups.
- The at-risk group exhibited significantly increased spatial heterogeneity in F and Bv compared to controls.
- These microcirculatory changes were detectable before conventional perfusion parameter alterations.
Conclusions:
- Myocardial perfusion CT can quantify subresolution microcirculatory distribution.
- Significant changes in myocardial perfusion and blood volume heterogeneity occur in hypercholesterolemia.
- Perfusion CT detects early microcirculatory dysfunction in atherosclerosis before epicardial stenosis.
Abstract:
Intramyocardial microvessels show functional changes in early stages of atherosclerosis prior to epicardial coronary artery stenosis. However, clinical CT does not have adequate spatial resolution to resolve the microvessels. To clinically detect changes in the function of the intramyocardial microcirculation, the spatial heterogeneity of the distribution of myocardial perfusion (F) and intramyocardial microcirculatory blood volume (Bv) was determined by perfusion CT. Two human subject groups were studied: (i) a "Control" group (24) with no risk factors nor evidence of coronary artery disease (CAD), and (ii) an "At-Risk" group (24) with hypercholesterolemia, but no evidence of CAD. In the perfusion CT image, a region of interest (ROI) covering the left ventricular myocardium was subdivided into multiple nested ROI (nROI) of equal size and used to compute F and Bv for each nROI. No significant differences between the groups were demonstrable in overall myocardial F, or Bv. The nROI data showed significantly increased spatial heterogeneity in the "At Risk" group when compared to "Control" subjects. This study demonstrates that subresolution distribution at the microcirculatory level can be quantified with myocardial perfusion CT and significant changes in these parameters occur in hypercholesterolemic subjects before they have developed significant changes in conventional perfusion parameters.
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