Evaluation of chronic carotid artery occlusion by non-contrast 3D-MERGE MR vessel wall imaging: comparison with 3D-TOF-MRA, contrast-enhanced MRA, and DSA

Objectives To analyze the accuracy of a non-contrast MR vessel wall imaging technique, three-dimensional motion-sensitized driven equilibrium prepared rapid gradient echo (3D-MERGE) for diagnosing chronic carotid artery occlusion (CCAO) characteristics compared with 3D time-of-flight (TOF) MRA, and contrast-enhanced MRA (CE-MRA), using digital subtraction angiography (DSA) as a reference standard. Methods Subjects diagnosed with possible CCAO by ultrasound were retrospectively analyzed. Patients underwent 3.0-T MR imaging with 3D-MERGE, 3D-TOF-MRA, and CE-MRA followed by DSA within 1 week. Diagnostic accuracy of occlusion, occlusion site, and proximal stump condition were assessed independently on 3 MRI sequences and DSA. Agreement of the above indicators was evaluated in reference to DSA. Results One hundred twenty-four patients with 129 suspected CCAO (5 with bilateral occlusions) met the inclusion criteria for our study. 3D-MERGE demonstrated a sensitivity, specificity, and accuracy of 97.0%, 86.7%, and 94.6%, respectively, with excellent agreement (Cohen's kappa= 0.85; 95% CI, 0.71, 0.94) for diagnosing CCAO in reference to DSA. 3D-MERGE was superior in diagnosing CCAO compared with 3D-TOF-MRA (Cohen's kappa= 0.61; 95% CI, 0.42, 0.77) and similar to CE-MRA (Cohen's kappa= 0.93; 95% CI, 0.86, 1.00). 3D-MERGE also had excellent agreement compared with DSA for assessing occlusion sites (Cohen's kappa= 0.85; 95% CI, 0.71, 0.97) and stump condition (Cohen's kappa= 0.83; 95% CI, 0.71, 0.94). Moreover, 3D-MERGE provided additional information regarding the occluded segment, such as distal lumen collapse and vessel wall lesion components. Conclusion 3D-MERGE can reliably assess chronic carotid occlusive characteristics and has the ability to identify other vessel wall features of the occluded segment. This non-contrast MR vessel wall imaging technique is promising for assessment of CCAO.