Follow-up of intracranial aneurysms treated with the Surpass flow diverter: comparison of subtraction CTA and DSA. Part II: a retrospective selected case series.

Using flow diverters (stent-like implants that divert the flow from the
aneurysm sac) to treat unruptured intracranial aneurysms is increasingly
accepted as the treatment of choice. Nowadays, the gold standard for
radiological follow*up (FU) to evaluate the degree of occlusion of aneurysms is
digital subtraction angiography (DSA). Some non-invasive diagnostic methods
have also been described, but there is a lack of evidence about their
reliability.
Subtraction CT angiography (sCTA) is a promising non-invasive technique with an
accurate spatial resolution that could theoretically provide the same
information as DSA.
As reported in the literature (occlusion rate 75-94% at 6-month FU), our
Surpass series shows that at the 6-month FU, some aneurysms are not occluded;
94% of those with a complete neck coverage had complete occlusion, whereas 50%
of the aneurysms with incomplete neck coverage were occluded. We follow these
cases with angiography until the aneurysm occludes. For this study, we will
select 10 consecutive cases with incomplete aneurysm occlusion and, by the next
angiographic FU, will add a sCTA to the standard DSA.

Primary objective:
-To determine the accuracy of sCTA compared to DSA in the visualisation of the
degree of occlusion in the FU of intracranial aneurysms treated with Surpass.

Secondary objectives:
-To determine the accuracy of sCTA compared to DSA in the visualisation of the
patency of parent vessels, and the correct deployment, position and apposition
of the Surpass.
-To assess the complications related to the two diagnostic methods.

Single centre, retrospective selected case series.

Patients will undergo a sCTA in addition to the standard follow-up DSA. This
will not lead to a longer admission, as we will schedule both studies on the
same day. This may mean that a patient has to stay in the hospital for a
slightly longer time (approximately 1 hour). As sCTA is a non-invasive
technique, with side-effects that only very rarely arise as a result of the
administration of the contrast agent, any additional risks are estimated to be
nearly zero.
An extra 50cc of contrast agent will be administered in addition to the
standard care DSA. Patients at risk of contrast-induced nephropathy will be
excluded from participation. Adverse reactions related to the use of the
contrast agent (Xenetix) are generally mild to moderate, and transient. The
adverse reactions most commonly reported are feeling of warmth, pain and oedema
at the injection site. The hypersensitivity reactions are usually immediate
(during the injection or over the hour following the start of the injection) or
sometimes delayed (one hour to several days after the injection).
The total amount of extra radiation that patients will receive at each sCTA is
2.6 mSv.