Quantification of vasa vasorum density in multi-slice computed tomographic coronary angiograms: role of computed tomographic image voxel size.

OBJECTIVE: This study is motivated by the possibility of using computed tomography (CT) to detect early coronary atherosclerosis by the increased CT values within the arterial wall resulting from vasa vasorum proliferation.
METHODS: Coronary arteries (n = 5) with early atherosclerotic changes were injected with Microfil and scanned (micro-CT). Noise was added to the CT projection data sets (to represent the radiation exposure of current clinical CT scanners) and then reconstructed to generate 3-dimensional images at different voxel sizes.
RESULTS: Higher CT values were detected because of contrast agent in vasa vasorum if voxel size was less than (150 microm)(3). Contrast in the main lumen increased the CT values dramatically at voxels greater than (100 microm)(3), whereas CT values of the same specimen without contrast in the main lumen remained constant.
CONCLUSIONS: Voxel sizes less than (200 microm)(3) are needed to quantitate arterial wall opacification due to vasa vasorum proliferation.