IMproving Risk PREdiction of Intracranial AneurysmS

Intracranial aneurysms are found in approximately 3% of the adult population.
Due to an increased use of imaging, the number of incidentally found unruptured
aneurysms grows. The optimal management of these aneurysms is still
controversial. Aneurysms are mainly treated when they are in the posterior
circulation or when they are larger than 7mm in diameter. However, most
incidentally found aneurysms are small and a proportion of these do rupture.
Therefore, better rupture risk predictors are necessary. It is hypothesized
that characteristics of the aneurysm wall have a predictive value for growth,
which is a surrogate outcome measure for rupture. Furthermore, it is thought
that flow patterns play a major role in the adherence of inflammatory cells and
the response of the endothelial cells to local inflammation.

The primary aim of this study is to evaluate the relation between wall
characteristics and recently detected aneurysm growth. The secondary aim is to
investigate the relation between intraaneurysmal hemodynamics and wall
characteristics.

This is a duo-center (AMC and UMCU), cross-sectional study. Wall thickness,
wall enhancement (related to inflammation), and flow patterns will be
investigated using 3T/7T Magnetic Resonance Imaging (MRI). Univariate analysis
will be performed to assess the association with recently detected aneurysm
growth. For all statistically significantly associated parameters a
multivariate logistic regression analysis will be performed to assess the
independent contribution of all parameters to aneurysm growth.

During a single session, 80 patients will receive 3T/7T MRI without contrast
agent to analyze the wall thickness, intraaneurysmal flow, and aneurysm
geometry followed by 3T/7T MRI with a gadolinium-based contrast agent to depict
aneurysm wall enhancement. The acquisition time will be approximately 60
minutes in total.

3T/7T MRI of all study parameters will be performed during a single session,
with a total acquisition time of approximately 60 minutes. The risk of
participation to this study is low. MRI is a safe imaging technique without
radiation exposure. For imaging of the wall enhancement, gadolinium-based
contrast agent will be administered. Side effects of the MRI contrast agent are
rare and usually harmless. Patients will be screened for contra-indications for
(7T) MRI and contrast agent. Patients participating in this study will receive
additional imaging of the aneurysm. Besides this potential benefit, individual
patients will not benefit directly from participation in this study. However,
we expect this study to lead to a better identification of growing aneurysms,
providing a better management of unruptured intracranial aneurysms.