To investigate the nature of carotid atherosclerotic plaques by carotid Doppler ultrasonography (CDU) and high resolution magnetic resonance imaging (HRMRI), and to assess the value of CDU in evaluating the nature of atherosclerotic plaques.

We retrospectively and consecutively enrolled 85 patients who were admitted to the Stroke Center of the First Affiliated Hospital of Soochow University and diagnosed with responsible plaques in the carotid artery through CDU and HRMRI examinations for symptoms such as acute ischemic stroke or transient ischemic attack between August 2017 and December 2020. CDU was used to assess the nature of carotid atherosclerotic plaques according to their morphology, echo, integrity of fibrous cap, and presence or absence of ulcer, and divide them into vulnerable plaques and stable plaques. HRMRI was also performed to assess the nature of atherosclerotic plaques according to the MRI classification criteria for atherosclerotic plaques, and divide them into vulnerable plaques and stable plaques. Using the HRMRI evaluation results as the noninvasive "gold standard", the receiver operator characteristic (ROC) curve for CDU assessment of plaque vulnerability was plotted to calculate the area under the curve, sensitivity, specificity, and Youden index. Cohen's kappa values were used to calculate the agreement between CDU and HRMRI in assessing carotid atherosclerotic plaque vulnerability.

Among the 85 responsible plaques, 49 were assessed as vulnerable plaques by HRMRI (49/85, 57.6%), and 46 were assessed as vulnerable plaques by CDU (46/85, 54.1%). According to the ROC curve, the area under the ROC curve for CDU assessment of carotid vulnerable plaques was 0.921, with a sensitivity of 89.8%, specificity of 94.4%, and Youden index of 0.842. Kappa test results showed that the consistency between CDU and HRMRI in assessing the nature of carotid atherosclerotic plaque was strong (Kappa value=0.833, P<0.05). The Cohen's kappa values for CDU and HRMRI in assessing the following characteristics of vulnerable carotid plaques were 0.905, 0.875, 0.839, 0.822, and 0.719 for lipid necrotic core/intraplaque hemorrhage, calcification, ulcerated plaques, thrombosis, and fibrous cap status, respectively.

CDU is an effective method for predicting carotid atherosclerotic plaque vulnerability and is able to accurately provide a sufficient basis for the selection of treatment options.