Magnetic Resonance Angiography After Flow Diversion: The Use of Complementary Magnetic Resonance Angiography Techniques to Monitor Aneurysm Occlusion and Device and Arterial Branch Patency After Flow Diverter Placement

Abstract

Background: Few studies have evaluated flow diversion with magnetic resonance angiography (MRA). Studies have shown better success of MRA in assessing the aneurysm response, but limited success in assessing stent patency. The patency of arterial branches on MRA remains to be explored.

Methods: Retrospective evaluation of 31 consecutive cases of carotid aneurysms treated with flow diversion was performed with noncontrast time-of-flight (TOF), contrast-enhanced TOF, and cine MRA (time-resolved angiography with interleaved stochastic trajectories) independently by 2 investigators for aneurysm occlusion, stent patency, and arterial branch patency. Digital subtraction angiography served as the gold standard technique.

Results: Patients were 6 men and 25 women with a mean ± SD age of 57.8 ± 12.27 years (range, 32-79 years). Stent patency, aneurysm occlusion, and branch patency mostly revealed substantial to perfect interobserver agreement (κ >0.60). Sensitivity, specificity, positive predictive value, and negative predictive value for stent patency on raw data images of TOF were 0.50, 0.86, 0.20, and 0.96 and on contrast-enhanced TOF were 1.0, 0.93, 0.50, and 1.0. Ranges for aneurysm response on the 3 MRA scans were 0.78-0.89 for sensitivity, 0.54-0.92 for specificity, 0.73-0.93 for positive predictive value, and 0.78-0.86 for negative predictive value. Ranges for arterial branch patency among the 3 MRA scans were 0.87-0.96 for sensitivity, 0.50-1.0 for specificity, 0.90-1.0 for positive predictive value, and 0.33-0.80 for negative predictive value.

Conclusions: Aneurysm occlusion, stent patency, and arterial branch patency in flow diversion can be successfully evaluated with the combination of 3 MRA techniques.

Keywords: Carotid stent; Flow diversion; Flow diverter; ICA aneurysm; MRA.