Advanced MRI in Abdominal Aortic Aneurysms

Abdominal aortic aneurysms (AAAs) are local dilatations of the abdominal aorta.
They are generally asymptomatic, but can grow or eventually rupture. Rupture of
an AAA is associated with high morbidity and mortality. Despite extensive
research, the pathogenesis of aneurysm growth and rupture is not fully
understood. Also, no clear rupture predictor has been identified to date.
Further research with imaging techniques can lead to a better understanding of
the pathogenesis of AAA growth and rupture.
This MRI study uses four-dimensional flow Magnetic Resonance Imaging (4D flow
MRI), Dynamic Contrast-Enhanced Magnetic Resonance Imaging (DCE-MRI) and T1/T2
mapping to visualise AAA characteristics.
4D flow MRI visualises blood flow. This enables the calculation of hemodynamic
characteristics of AAA. DCE-MRI can visualise vessel wall microvasculature in
the AAA wall. With T1/T2 mapping, the composition of intraluminal thrombus
(ILT) can be measured.
These characteristics are thought to play a role in AAA rupture. Since these
MRI sequences have only been explored in a handful of AAA studies, they will
need to be tested for feasibility and reproducibility. It will also be tested
whether the outcomes of these MRI sequences are associated with AAA diameter.

1: Feasibility: to assess whether 4D flow MRI, DCE-MRI and T1/T2 mapping
sequences can produce high-quality images that enable the calculation of the
primary parameters wall shear stress (WSS), kinetic transport constant (Ktrans)
and T1/T2 relaxation time;

2: Reproducibility: to assess the reproducibility of 4D flow MRI, DCE-MRI and
T1/T2 mapping results in AAA by calculating interscan, intra- and interobserver
variability;

3: Association with disease severity: to assess whether WSS, Ktrans and T1/T2
relaxation time each are associated with aneurysm diameter. We hypothesise that
WSS is inversely associated with aneurysm diameter, and that Ktrans is
positively associated with aneurysm diameter.

Multicentre cross-sectional cohort pilot study. This study comprises of two
phases. In the first phase, 5 patients with an AAA undergo a single MRI
examination to optimise the MRI sequences. In the second phase, a maximum of 30
patients with an AAA will be included to assess the three main objectives.

This is a non-invasive MRI study with the use of a contrast medium. All risks
associated with this study are related to the use of the contrast medium. This
study uses Gadovist as its contrast medium, which is registered for use in MRI
research. Its complications are rare. Participation in this study may cause
some discomfort to the patient due to the MRI scan time of approximately 45
minutes. The total MRI visit including all preparations will take approximately
2 hours.
Five patients will only be scanned once and a maximum of thirty patients will
be scanned twice to assess reproducibility. The maximal number of visits is
three per patient.
Lastly, participants will have no direct benefit from participation in this
study.