Evaluation of CTA, time-resolved 4D CE-MRA and DSA in the follow-up of an intracranial aneurysm treated with a flow diverter stent: Experience from a single case

Abstract

Endovascular treatment of giant, fusiform and dissecting aneurysms with flow diverter stents is becoming more and more popular. However, very few studies on the follow-up have been published. We describe a patient with a dissecting aneurysm of the right vertebral artery treated with flow diverter stent placement. The patient was followed up with CT angiography (CTA), time-resolved contrast-enhanced MR angiography (CE-MRA) and digital subtraction angiography (DSA). CTA had false negative results in two instances, whereas time-resolved CE-MRA and DSA were the most accurate in depicting the residual flow in the aneurysmal sac. However, in the case of DSA the demonstration of residual flow proved quite difficult and required a very thorough examination with oblique projections. Our 2.5-year experience with this patient led us to believe that time-resolved CE-MRA is a valuable tool in the follow-up of flow diverter-treated stents.

Keywords: CT angiography; Intracranial aneurysm; contrast-enhanced MR angiography; digital subtraction angiography; flow diverter.

Figure 1.

A) Antero-posterior DSA shows a dissecting aneurysm of the distal part of the right vertebral artery. B) Coronal maximum intensity projection (MIP) reconstruction of a CTA, 1 month after endovascular treatment, shows an apparent exclusion of the aneurysm from the circulation. The stent is clearly appreciated. C) Coronal MIP reconstruction of time-resolved CE-MRA (TRICKS) 2 months after the CTA demonstrates residual flow in the distal part of the aneurysmal sac (arrow).

Figure 2.

A) Coronal maximum intensity projection (MIP) reconstruction of time-resolved CE-MRA (TRICKS) 2 years after stenting shows a decrease in the residual flow within the aneurysmal sac (white arrow). B) In the subsequent DSA it is hard to discern the residual flow seen in the CE-MRA because the leakage was distributed around the stent and there was overlap. C) In a later phase an area of slower flow can be appreciated around the stent, representing the residual flow within the sac (black arrow).