Scan-Rescan Reproducibility of Carotid Atherosclerotic Plaque Morphology and Tissue Composition Measurements Using Multicontrast MRI at 3T

Purpose: To evaluate interscan reproducibility of both vessel morphology and tissue composition measurements of carotid atherosclerosis using a fast, optimized, 3T multicontrast protocol. Materials and Methods: A total of 20 patients with carotid stenosis >15% identified by duplex ultrasound were recruited for two independent 3T MRI (Philips) scaris within one month. A multicontrast protocol including five MR sequences was applied: TOF, T1-/T2-/PD-weighted and magnetization-prepared rapid acquisition gradient-echo (MP-RAGE). Carotid artery morphology (wall volume, lumen volume, total vessel volume, normalized wall index, and mean/maximum wall thickness) and plaque component size (lipid rich/necrotic core, calcification, and hemorrhage) were measured over two time points. Results: After exclusion of images with poor image quality. 257 matched locations from 18 subjects were available for analysis. For the quantitative carotid morphology measurements. coefficient of variation (CV) ranged from 2% to 15% and intraclass correlation coefficient (ICC) ranged from 0.87 to 0.99. Except for maximum wall thickness (ICC = 0.87), all ICC were larger than 0.90. For the quantitative plaque composition measurements, the ICC of the volume and relative content of lipid rich/necrotic core and calcification were larger than 0.90 with CV ranging from 22% to 32%. Conclusion: The results from the multicontrast high-resolution 3T MR study show high reliability for carotid morphology and plaque component measurements. 3T MRI is a reliable tool for longitudinal clinical trials, with shorter scan time compared to 1.5T.