Simultaneous magnetic resonance imaging of carotid artery perivascular adipose tissue and vessel wall: A feasibility and repeatability study

Background It has been shown that rupture of vulnerable plaques of atherosclerosis (AS) is one of the main causes of ischemic stroke. Increasing evidence suggests that the inflammatory changes of perivascular adipose tissue (PVAT) were independently associated with both vulnerable plaque characteristics and cerebrovascular symptoms. Therefore, it is essential to conduct non‐invasive joint assessment of carotid AS plaques and PVAT characteristics for better stratifying the risk of ischemic cerebrovascular events. Purpose To develop a simultaneous magnetic resonance (MR) imaging technique for carotid artery PVAT and vessel wall, and determine its feasibility and repeatability. Methods This study developed an MR sequence for simultaneous imaging carotid vessel wall and PVAT. Seventeen healthy subjects and nine patients with carotid AS were recruited for MR imaging experiments, of whom five healthy subjects were selected for the repeatability test. All participants underwent bilateral carotid three‐dimensional MR imaging by acquiring the proposed iMSDE‐mDIXON, MERGE, and mDIXON sequences. To evaluate the reliability of the proposed iMSDE‐mDIXON sequence, we analyzed its agreement in measuring morphology (lumen area, wall area, mean wall thickness, and normalized wall index) of carotid wall with the reference sequence of MERGE, as well as its agreement in quantifying carotid PVAT (PVAT area, proton density fat fraction [PDFF], area index, and volume index) with the reference sequence of mDIXON. The interclass correlation coefficient (ICC) and Bland–Altman plots were conducted in statistical analysis. Results The proposed iMSDE‐mDIXON technique demonstrated high reliability in quantifying carotid vessel wall morphology (healthy subjects: ICC = 0.903–0.997; patients: ICC = 0.928–0.999) and PVAT morphology (healthy subjects: ICC = 0.906–0.988; patients: ICC = 0.957–0.996). Although iMSDE‐mDIXON sequence showed potential in assessing carotid AS, there was a substantial bias (>20%) in PDFF quantification. Nevertheless, moderate to excellent agreement was maintained between iMSDE‐mDIXON and mDIXON in measuring PVAT PDFF both in healthy subjects (ICC: left, 0.782; right, 0.740) and AS patients (ICC: left, 0.790; right, 0.628). In addition, the proposed sequence showed excellent agreement in quantifying carotid vessel wall (ICC = 0.845–0.999) and PVAT morphology (ICC = 0.841–0.989) between the repeated scans. Conclusions This study proposed an iMSDE‐mDIXON sequence that enables simultaneous imaging of the carotid vessel wall and PVAT in a single scan with high efficiency, reliability, and repeatability. This technique has considerable potential for jointly characterizing the changes of PVAT and pathology of the vessel wall in carotid artery.