Long-Term Effect of Flow Diversion on Large and Giant Aneurysms: MRI-DSA Clinical Correlation Study

Background

The long-term effect of flow diversion (FD) on aneurysms has not been well studied.

Objective

We aimed to assess the effect of the Pipeline embolization device (Covidien, Irvine, California, USA) on large and giant intracranial aneurysms with magnetic resonance imaging (MRI) and digital subtraction angiography (DSA) and then correlate with clinical follow-up.

Methods

We conducted a retrospective analysis of aneurysms treated solely with Pipeline without adjunctive therapy. The largest aneurysm diameters were compared with pretreatment and post treatment MRI and correlated with DSA and clinical symptoms.

Results

Twelve patients harboring large and giant saccular unruptured aneurysms, treated with Pipeline, were included. Mean follow-up times were as follows: MRI 22.8 months (range 1−57), DSA 18.2 months (range 1−33), and clinical 29 months (range 1−48). Ten (83%) of 12 treated aneurysms decreased in size on MRI, which was first seen at an average of 17 months (range 4−57). In 70% of patients the change was noted on MRI ≤1 year after treatment, at an average of 9.1 months (range 4−12). MRI reduction was more likely in angiographically occluded aneurysms. Five aneurysms with complete occlusion on early angiogram showed size reduction on MRI only at ≥12 months. Mean aneurysm size reduction was 57% (range 19.6−94.2), which correlated well with improvement of cranial neuropathies in 75% and headaches in 100% of patients.

Conclusion

Most aneurysms treated with Pipeline decreased in size, correlating with clinical improvement. Some aneurysms remained unchanged on MRI until a later time point despite early DSA occlusion. It may be reasonable to eliminate early postprocedural imaging and start follow-up only as late as 1 year after FD treatment in clinically stable, asymptomatic patients.

Introduction

Flow diverters have ushered a paradigm shift in the treatment of intracranial aneurysms, especially large and giant, wide-necked aneurysms.¹ These aneurysms are challenging lesions to treat by both surgical and endovascular approaches. Traditional endovascular reconstructive methods, such as aneurysm sac coiling even with advanced adjunctive techniques, are associated with low rates of angiographic occlusion and high rates of recurrence.2, 3 Intravascular flow diversion (FD) has been proposed recently for large and giant aneurysms. Multiple studies have demonstrated successful exclusion of these aneurysms from the circulation after FD treatment. However, the long-term effect of FD on the aneurysm sac has not been well studied. We assessed the effects of FD with the Pipeline embolization device (Covidien, Irvine, California, USA) on large and giant aneurysms using magnetic resonance imaging (MRI), digital subtraction angiography (DSA), and clinical follow-up.