Evaluation of the Time-Dependent Changes and the Vulnerability of Carotid Plaques Using Contrast-Enhanced Carotid Ultrasonography

Background: The association of carotid plaque enhancement on contrast-enhanced carotid ultrasound (CEUS) and plaque vulnerability evaluated by magnetic resonance imaging (MRI) was to be determined. Materials and methods: The 103 patients underwent CEUS from May 2013 until June 2016. CEUS images of the carotid plaque were obtained offline. Plaque images obtained at 1, 3, 5, and 10 minutes were compared with the reference image, defined as the image obtained at 0 minute. Plaque brightness was assessed using the gray-scale median during contrast enhancement (GSM-C). Plaque vulnerability was evaluated using T1- and T2-weighted MRI and Volume ISotropic TSE Acquisition (VISTA), with a VISTA cutoff value for the plaque muscle ratio (PMR) of 1.5. Time-dependent changes in the GSM-C were evaluated, and those between 0 and 1 minute were compared with the PMR values determined on MRI. Findings: GSM-C decreased significantly over time, from 32.0 at 0 minute to 28.0 at 1 minute, 25.0 at 3 minutes, and 19.0 at 10 minutes. The greater the increase in the changes in the GSM-C from 0 to 1 minute, the more significant the association with a PMR higher than the median on T1 (GSM-C: 0 minute: 29.0, 1 minute: 24.0, P = .015), a PMR less than or equal to the median on T2 (0 min: 35.0, 1 min: 28.0, P = .003), and a PMR more than 1.5 determined on VISTA (GSM-C: 0 minute: 29.0, 1 minute: 24.0, P = .005). Conclusions: Early changes in the GSM-C evaluated with CEUS indicate significant plaque vulnerability on MRI.