Hemodynamic consequences of intra arterial treatment of intracranial aneurysms using non-invasive quantitative flow measurements from arterial spin labeling techniques in high field strength MRI.

Arterial Spin Labeling (ASL) is a recently developed method that allows
selective, quantitative and non-invasive measurements of specific perfusion
territories of the larger cerebral arteries. These techniques may be of great
importance in the choice of therapy in patients with cerebrovascular disease.
Yet ASL techniques are not fully implemented within the UMCG.

Extensive research on this subject has been done by former doctoral student Van
Laar and radiologist Hendrikse et al of the UMCU. A large variability of
ipsilateral perfusion territories has been demonstrated in a group of patients
with symptomatic occlusion of the ICA. Within these patients the perfusion
territory of the MCA on the occluded side was largely supplied by collaterals
originating from the VBA while the contralateral ICA contributed significantly
to the perfusion territory of both ACA*s. A large part of this redistribution
of blood flow was related to the Circle of Willis. The configuration of the
Circle of Willis appears to strongly affect the extent of cerebral perfusion
territories.

To further implement the ASL techniques in this study the perfusion territories
of the larger cerebral arteries are compared before and after endovascular
treatment of intracranial aneurysms. As to our best knowledge few studies have
been conducted on the non-invasive follow-up of coiled intracranial aneurysms.
Most studies aim to identify the diagnostic potential of 3D TOF sequences. The
study to be conducted allows non-invasive judgement of collateral circulation
and identification of areas at increased risk of ischemia. The goal of the
study is to determine to what extent perfusion territories and cerebral border
zones are affected by endovascular treatment of intracranial aneurysms.
Information on the relationship between chosen endovascular treatment and
hemodynamic consequences could be of influence in the future approach of
patients.

Primary objective:
- Determining the extent to which perfusion territories of the
larger intracranial arteries are affected by endovascular treatment of
intracranial aneurysms

Secondary objectives:
- Defining the relationship between collateral circulation and the
anatomy and blood flow direction of the circle of Willis.
- Examine alterations in post-treatment cerebral border zones.

This research will be conducted as a pilot study in a 7 month period that will
take place in the Neuroimaging Center in Groningen. Adult patients with a
unruptured aneurysms who have been selected for elective endovascular treatment
will be asked to participate in the study by means of informed consent. Before
treatment an ASL perfusion scan will be performed. In the follow-up additional
sequences will be added to the existing scanning protocol: pCASL and PC MRA of
the circle of Willis.

All participants will receive an additional MRI scan prior to treatment.
Patients will be asked to hold still during the procedure. In the follow-up
additional sequences will be added to the existing scanning protocol. These
sequences have been tested on healthy volunteers. The safety of the used
materials (coils and stents) in a 3 T MRI system is verified using information
on the website MRIsafety.com.