High signal intensity halo around the carotid artery on maximum intensity projection images of time‐of‐flight MR angiography: A new sign for intraplaque hemorrhage

Abstract

Purpose:To evaluate the value of the high signal intensity halo sign as a new marker of a fresh or recent intraplaque hemorrhage on the maximum intensity projection (MIP) images of time-of-flight (TOF) MR angiography. Materials and Methods:A total of 135 consecutive patients were included in this study. High-resolution MRI using 3-inch surface coils was performed on a 1.5T scanner before the carotid endarterectomy. TOF MR angiograms and T2-weighted, T1-weighted pre-and postcontrast fast spin echo images were obtained. The surgical and pathological findings of the carotid artery were analyzed and correlated with the MRI findings.Results: A total of 42 atheromas (31.1%) had a fresh or recent intraplaque hemorrhage on the surgicopathological findings. A total of 38 (90.5%) of these patients showed high signal intensity halo around the carotid artery on the MIP images of TOF MR angiography. The high signal intensity halo sign, compared with the surgical and histopathological findings, demonstrated a sensitivity, specificity, positive predictive value, and negative predictive value of 91%, 83%, 72%, and 95%, respectively, with a 95% confidence interval (CI) in the detection of an intraplaque hemorrhage. The multisequence approach suggested the presence of an intraplaque hemorrhage with a sensitivity, specificity, positive predictive value, and negative predictive value of 93%, 85%, 74%, and 96%, respectively, with a 95% CI. Conclusion:High signal intensity halo around the carotid artery on the MIP images of TOF MR angiography is useful in the noninvasive detection of a fresh or recent carotid intraplaque hemorrhage.

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

“…In our study, the sensitivity of high signal intensity on MIP images of TOF MRA for detecting IPH was 67.1%. This sensitivity was lower than that of previous studies that only used TOF MRA to evaluate IPH (6,9), and higher than a previous comparison study between TOF MRA and carotid plaque MR In our study, the total IPH volume and maximal axial area was significantly higher with a positive halo sign on MIP of TOF MRA than with a negative halo sign. This result was consistent with a previous study (1).…”

“…These include conventional T1-weighted fast spin echo, TOF MRA, or MPRAGE sequences. Several studies have used TOF sequencing to detect carotid IPH, and a routine MRA protocol without additional sequences to evaluate carotid atherosclerosis (1,5,9,15). The appearance of a halo sign around the carotid artery on the MIP of the TOF MRA was useful for the noninvasive detection of a fresh or recent carotid IPH on histologic analysis (6,9).…”

“…However, a carotid TOF sequence has been widely used for detecting IPH because it was included in the routine protocol for brain MR examination and this approach can be time efficient, without the need for additional sequences such as MPRAGE. Maximum intensity projection (MIP) images from TOF MR angiography (MRA) can also show IPH as a high signal intensity (6,9). This finding indicates the possibility of an additional application of MIP from TOF MRA to investigate carotid artery stenosis.…”

Use of Magnetic Resonance Imaging to Predict Outcome after Stroke: A Review of Experimental and Clinical Evidence

“…Another interesting application of MRA in stroke is its use to identify several characteristics of the atherosclerotic build up that could provide indications of plaque vulnerability (reviewed in Saam et al, 2007). For example, TOF was able to delineate the boundaries of the inflammatory fibrous cap rupture in atherosclerotic patients (Mitsumori et al, 2003), as well as fresh intraplaque hemorrhage (Yim et al, 2008). In addition, contrast agents, specifically ultrasmall superparamagnetic iron oxide nanoparticles, have been shown to accumulate inside the macrophages contained in the fibrous cap (Kooi et al, 2003), which could also enhance predictability of rupture potential.…”

Safety of Protected Carotid Artery Stenting in Patients with Severe Carotid Artery Stenosis and Carotid Intraplaque Hemorrhage

“…Carotid IPH can be identified in T1-weighted MR imaging sequences. [11][12][13] The presence of IPH at high risk of causing thromboembolic events may increase the risk of distal embolization during the carotid revascularization procedures. However, no studies investigating the safety of CAS in patients with carotid IPH have been previously conducted.…”