ORIGINAL RESEARCH EXTRACRANIAL VASCULAR Carotid Artery Plaque Characterization Using CTMultienergy

BACKGROUNDANDPURPOSE: Carotid artery plaque types can be categorizedwith CT according to their HU values. The purpose of this work was to analyze carotid artery plaque characteristics by using multienergy imaging. METHODS AND MATERIALS: Thirty-two consecutive patients (23 men; median age, 70 years) were retrospectively analyzed. Carotid arteries were studiedwith amultienergy CT scanner. All patients received a 15-mL timing bolus of contrastmedium to synchronize the data acquisition followed by an injection of 60 mL of contrast medium at a 5-mL/s flow rate. Plaque analysis in 64 carotid arteries was performed, and datasets were reconstructed by using a dedicated workstation. For each plaque, the HU value was quantified with a 2-mm-square region of interest at monoenergy values of 66, 70, 77, and 86 keV. TheWilcoxon test was used to test the differences in HU values in the plaques at different kiloelectron volts. RESULTS: Four carotid arteries were excluded due to the absence of plaque, and another 7, because of the presence of calcified plaques. In the remaining 53 carotid arteries, Wilcoxon analysis showed a statistically significant difference in HU values among the monoenergy values of 66, 70, 77, and 86 keV (P .0001). In particular, we found that with the increase in monochromatic kiloelectron volt values, there is a statistically significant reduction in the HU value of the plaque. CONCLUSIONS: Results of this study suggest that the HU values of plaque may significantly change according to the selected kiloelec-tron volt; therefore, the HU-based plaque type (fatty, mixed, calcified) should be classified according to the energy level applied