Utility of Complementary Magnetic Resonance Plaque Imaging and Contrast-Enhanced Ultrasound to Detect Carotid Vulnerable Plaques

Background-We aimed to improve the assessment quality of plaque vulnerability with combined use of magnetic resonance imaging and contrast-enhanced ultrasound (CEUS). Methods and Results-We prospectively enrolled 71 patients with internal carotid artery stenosis who underwent carotid endarterectomy and performed preoperative CEUS and magnetic resonance plaque imaging. We distinguished high-signal-intensity plaques (HIPs) and non-HIPs based on magnetization-prepared rapid acquisition with gradient echo images. We graded them according to the CEUS contrast effect and compared the CEUS images with the carotid endarterectomy specimens. Among the 70 plaques, except 1 carotid endarterectomy tissue sample failure, 59 were classified as HIPs (43 symptomatic) and 11 were classified as non-HIPs (5 symptomatic). Although the magnetization-prepared rapid acquisition with gradient echo findings alone had no significant correlation with symptoms (P=0.07), concomitant use of magnetization-prepared rapid acquisition with gradient echo and CEUS findings did show a significant correlation (P<0.0001). CEUS showed that all 5 symptomatic non-HIPs had a high-contrast effect. These 5 plaques were histopathologically confirmed as vulnerable, with extensive neovascularization but only a small amount of intraplaque hemorrhage. Conclusions-Complementary use of magnetic resonance imaging and CEUS to detect intraplaque hemorrhage and neovascularization in plaques can be useful for evaluating plaque vulnerability, consistent with the destabilization process associated with neovessel formation and subsequent intraplaque hemorrhage.