Carotid Intraplaque Hemorrhage Imaging: Diagnostic Value of High Signal Intensity Time-of-Flight MR Angiography Compared with Magnetization-Prepared Rapid Acquisition with Gradient-Echo Sequencing

Purpose: To determine the value of the appearance of the high signal intensity halo sign for detecting carotid intraplaque hemorrhage (IPH) on maximum intensity projection (MIP) of time-of-flight (TOF) MR angiography (MRA), based on high signal intensity on magnetization-prepared rapid acquisition with gradient-echo (MPRAGE) sequencing. Materials and Methods: A total of 78 carotid arteries in 65 patients with magnetization-prepared rapid acquisition gradient-echo (MPRAGE) positive on carotid plaque MR imaging were included in this study. High-resolution MR imaging was performed on a 3.0-T scanner prior to carotid endarterectomy or carotid artery stenting. Fast spin-echo T1- and T2-weighted axial imaging, TOF, and MPRAGE sequences were obtained. Carotid plaques with high signal intensity on MPRAGE > 200% that of adjacent muscle on at least two consecutive slices were defined as showing IPH. Halo sign of high signal intensity around the carotid artery was found on MIP from TOF MRA. Continuous and categorical variables were compared among groups using the Mann-Whitney test and Fisher's exact tests. Results: Of these 78 carotid arteries, 53 appeared as a halo sign on the TOF MRA. The total IPH volume of patients with a positive halo sign was significantly higher than that of patients without a halo sign ($75.0{\pm}86.8$ vs. $16.3{\pm}18.2$, P = 0.001). The maximum IPH axial wall area in patients with a positive halo sign was significantly higher than that of patients without a halo sign ($11.3{\pm}9.9$ vs. $3.7{\pm}3.6$, P = 0.000). Conclusion: High signal intensity halo of IPH on MIP of TOF MRA is associated with total volume and maximal axial wall area of IPH.