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 (CE-MRA). 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.