Plaque characterization may benefit from the increasing distinctiveness of the attenuating properties of different soft
plaque components at lower energies. Due to the relative slight increase in the CT number of the nonadipose soft plaque
at lower tube voltage settings vs. adipose plaque, a higher contrast between atheromous adipose and non-adipose plaque
may become visible with modern 64 slice systems. A contrast-detail (C-D) phantom with varying plaque composition as
the contrast generating method, was imaged on a commercial 64 slice MDCT system using 80, 120, and 140 kVp
settings. The same phantom was also imaged on a Cone Beam CT (CBCT) system with a lower tube voltage of 75 kVp.
The results of experiments from four different observers on three different plaque types (lipid, fiber, calcific) indicate
that CT attenuation within lipid cores and fibrous masses vary not only with the percentage of lipid or fiber present, but
also with the size of the cores. Furthermore, the C-D curve analysis for all three plaque types reveals that while the noise
constraints prevent visible differentiation of soft plaque at current conventional 64 slice MDCT settings, CBCT exhibits
superior visible contrast detectability than its conventional counterpart, with the latter having appreciably better
resolution limits and beneficial lower tube voltages. This low voltage CT technique has the potential to be useful in
composition based diagnosis of carotid vulnerable atherosclerotic plaque.