Pseudostenosis at the Origin of the Vertebral Artery on Contrast-enhanced MRA: Correlation with Aortic Motion on Dynamic 3D Time-Resolved Contrast-Enhanced MRA

Abstract

Purpose : The origin of the vertebral artery (VA) is a frequent site of pseudostenosis on contrast-enhanced MRA (CEMRA). The purpose of this study is to evaluate the relationship between the motion of the aortic arch and pseudostenosis at the origin of the VA. Materials and Methods: Our study had approval of our institutional review board. 47 patients underwent CT angiography (CTA), CE-MRA, and 3D time-resolved contrast-enhanced MRA (TR-CEMRA) within 6.87±9.89 days (mean±SD). Percent stenosis using the NASCET criteria was measured on CTA and CE-MRA. CTA was used as a reference standard to classify the CE-MRA into pseudostenosis and control group. Pseudostenosis was determined as 50%99% stenosis observed on CE-MRA but normal to less than 50% stenosis on CTA. Aortic motion (distance between the highest position and lowest position of aortic arch) was measured on TR-CEMRA. Age, route of intravenous contrast media, motion of aortic arch, and normal distal diameter of VA were compared between the two groups. Results: There were 17 patients and 23 vertebral arteries of pseudostenosis. Patients with pseudostenosis showed more aortic motion (3.61±1.88 vs. 2.05±1.97 mm) and older age (71.29±8.88 vs. 62.32±13.19 year-old). Route of intravenous contrast media and normal distal diameter of VA were not associated with pseudostenosis. Conclusion: VA origin is a frequent site of pseudostenosis. Older age and more motion of aortic arch are associated with pseudostenosis on CE-MRA.