Identification of Intraplaque Hemorrhage on MR Angiography Images: A Comparison of Contrast-Enhanced Mask and Time-of-Flight Techniques

Abstract

BACKGROUND AND PURPOSE MRA is widely used to measure carotid narrowing. Standard CE- and TOF-MRA techniques use highly T1-weighted gradient-echo sequences that can detect T1 short blood products, so they have the potential to identify IPH, an indicator of plaque rupture. We sought to determine the accuracy and reliability of these MRA sequences to detect IPH. MATERIALS AND METHODS 3D TOF and CE carotid MRA scans were obtained at 3T on 15 patients (age range, 58–86 years; 13 men) scheduled for CEA. The source images from the precontrast (mask) CE-MRA and the TOF sequences were reviewed by 2 independent readers for IPH presence (identified as hyperintense signal intensity compared with adjacent muscle). CEA specimens were stained with antibody against glycophorin A and Mallory stain to detect IPH and were correlated with MR images. RESULTS Nine of 15 CEA specimens (61 of 144 MR images) contained IPH confirmed by histology. Compared with TOF, CE-MRA mask demonstrated greater sensitivity, specificity, PPV, and NPV for IPH detection. The accuracy for correctly identifying IPH by using CE-MRA mask images and TOF images was 94% and 84%, respectively. Inter- and intraobserver agreement for IPH detection was excellent by mask images (κ = 0.91 and κ = 0.94, respectively) and TOF images (κ = 0.77 and κ = 0.84, respectively). CONCLUSIONS CE-MRA mask images are highly accurate and reliable for identifying IPH, more so than the TOF sequence, and can potentially provide valuable information about risk for rupture.

Intraplaque High-Intensity Signal on 3D Time-of-Flight MR Angiography Is Strongly Associated with Symptomatic Carotid Artery Stenosis

“…9 Neither of these techniques are part of the standard sequences routinely obtained in MRA examinations, which rely on TOF techniques to assess luminal diameter stenosis. Recent reports have suggested that routinely performed MRA techniques used to measure stenosis, including 3D-TOF imaging, 13,14 can accurately predict IPH compared with histopathologic studies by the detection of intraplaque high-intensity signal (IHIS) relative to adjacent skeletal muscle. These studies, however, have been performed by use of dedicated carotid coils and not by standard quadrature neck array coils.…”

Use of Contrast-enhanced Carotid Ultrasonography in Preoperative Assessment for Carotid Artery Stenting

“…T1-weighted BB-MRI and TOF MRA have been reported as indicators of plaque stability. [1][2][3] Unstable findings with high intensity on BB-MRI and TOF MRA were considered to indicate the presence of intra-plaque hemorrhage and neovascularization. Plaque enhancement on CEUS has also been reported as an indicator of intraplaque neovascularization, fibrous cap degradation, and plaque inflammation, leading to the increased adoption of this new imaging modality in the assessment of plaque stability.…”

“…Assessment of carotid artery plaques prior to CAS is typically done with carotid ultrasonography (US), T1-weighted black-blood MRI (BB-MRI), or time-of-flight MRA (TOF MRA). [1][2][3] In recent years, however, contrastenhanced carotid ultrasonography (CEUS) using an ultrasound contrast agent has become a viable modality for diagnosing intra-plaque neovascularization in the carotid artery, and it has attracted attention as a novel plaque imaging technique. 4) In the present study, the validity of CEUS in evaluation of plaque vulnerability was investigated by analyzing the relationship between the findings of preoperative plaque imaging including CEUS and the amount of debris retrieved during CAS.…”

Carotid Plaque Characterization Using 3D T1-Weighted MR Imaging with Histopathologic Validation: A Comparison with 2D Technique

“…5,6,[14][15][16][17] However, various imaging techniques have been applied to T1WI, with varying results, including conventional 2D-SE/FSE, 5,8 cardiac-gated multiple inversion-recovery black-blood 2D-FSE, 6 MPRAGE, 16,18,19 and source images of 3D time-of-flight MR angiography. 15,20,21 A recent study performing direct comparisons among these techniques found that 2D-SE imaging could more readily discriminate among fibrous, lipid-rich, necrotic, and hemorrhagic plaques because the T1 contrast can be maximized and stabilized under the appropriate scanning parameter settings. 7 In addition, the 2D-SE T1WI could accurately estimate intraplaque composition and could monitor temporal changes during medical treatment.…”