Authors: Regina Moritz Jill L Anderson Andrew J Vercnocke Robert J Wentz Erik L Ritman
Publish Date: 2013/02/27
Volume: 29, Issue: 6, Pages: 1325-1333
Abstract
To evaluate the potential of wholebody CT to detect localized areas of decreased or increased vascularity in coronary arterial walls We used both microsphere embolization of coronary artery vasa vasorum to generate small areas of hypoperfusion and surrounding hyperperfusion of the arterial wall and dietinduced hypercholesterolemia As a stimulus for localized angiogenesis such as occurs in early plaque formation in the coronary arterial wall microspheres were injected selectively into the LAD coronary artery lumens of anesthetized pigs Fourteen pigs acute then had a segment of their LAD harvested during injection of contrast medium and snapfrozen for subsequent cryostatic microCT An additional thirteen pigs chronic were allowed to recover fed a high cholesterol diet and 3 months later were again anesthetized and a segment of the LAD artery harvested and scanned The spatial distribution of the contrast agent within the arterial wall was measured in contiguous microCT images at right angles to the lumen axis with the area of wall in each crosssectional image being approximately 01 mm3 in size In the acute animals there were no localized areas of increased contrast around the hypoperfused embolized perfusion territories in the arterial wall but in the chronic animals the hypoperfused areas were surrounded by increased contrast These results suggest that CT might be able to detect localized regions of increased vascularity in the arterial wall as an indicator of early atherosclerotic stimulation of vasa vasorum proliferationThis work was supported in part by National Institutes of Health grants HL065342 and EB000305 We thank Dr V Herasevich and Ms Kay D Parker for helping to perform some of the animal studies and Ms Delories C Darling for editing and formatting this manuscriptUpper panel is a schematic of an enface view of an unrolled coronary artery wall The darker gray elliptical anulus is the hyperemic zone around the hypoperfused zone The lower panel plots the average circumferential CT gray scale of the total wall CT gray scale value within each contiguous transverse slice along the axis of the arterial lumenNoise in the perfusion profile as well as deviations of the hypoperfused area’s shape from elliptical made it difficult to use an analytical solution to calculate the CT2 and Dy variables Hence we adjusted an estimate of the values of Dy and CT2 empirically by overlaying a plot of the model onto the perfusion profile and then adjusting the variables until the model best fit to the perfusion profile such that the modeled profile in the regions around overlinetextCT hboxmin and overlinetextCT hboxmax
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