Study being continued as a multi centre MA3RS study.The patients will be followed up under MA3RS and AAA PET.

The aorta is the main blood vessel that comes out of the heart and distributes blood to the whole body. In some people, the aorta becomes swollen (aneurysm) and bursts, especially as it passes through the abdomen. These 'abdominal aortic aneurysms' often occur without symptoms and can burst or rupture without warning. This usually leads to death and represents the thirteenth commonest cause of death in the United Kingdom. In this study, we are looking at a new technique that can look at the aortic aneurysm using magnetic resonance imaging; a technique that does not require x-rays or radiation. We have recently shown that, using magnetic resonance combined with a new imaging agent USPIO, we can detect 'hotspots' of activity in these aneurysms that seem to predict which aneurysms grow rapidly, and are therefore potentially at risk of rupture. We here propose to conduct a study in Edinburgh that will invite all patients who are under surveillance because of an aneurysm. We will image these patients using this novel technique and see if we can identify which patients burst their aneurysm, have an aneurysm that grows so large it needs to have surgery, or die. This will be important to establish as it will potentially lead to a new way of managing people that could ultimately save lives. This is particularly timely as national screening and surveillance programmes are currently being launched.

HYPOTHESIS We hypothesise that uptake of ultrasmall supraparamagnetic particles of iron oxide into the aortic wall will predict abdominal aortic aneurysm growth and clinical outcomes.

Inclusion Criteria:

Patients with an abdominal aortic aneurysm >40 mm

Exclusion Criteria:

1. Any medical history or clinically relevant abnormality identified on the screening medical examination, vital sign measurement, or clinical laboratory examination that is deemed by the principal investigator and/or designee to make the subject ineligible for inclusion.

2. Subjects with planned AAA surgery.

3. Renal impairment with eGFR of <30 mls/min at screening, history of kidney transplant or history of contrast nephropathy.

4. Women of child-bearing potential without contraception,

5. Collagen-vascular disease.

6. Inability to undergo magnetic resonance or computed tomography scanning,

7. Contraindication to MRI scanning (as assessed by local MRI safety questionnaire) which includes but not limited to:

   • Intracranial aneurysm clips (except Sugita) or other metallic objects,
   • History of intra- orbital metal fragments that have not been removed,
   • Pacemakers, implantable cardiac defibrillators and non-MR compatible heart valves,
   • Inner ear implants,
   • History of claustrophobia in MR.

The investigators will recruit 237 patients with abdominal aortic aneurysms from the clinical surveillance programme at the Royal Infirmary, Edinburgh. Inclusion criteria will be patients with an abdominal aortic aneurysm >40 mm on ultrasound scanning. Exclusion criteria will include patients with anticipated or planned abdominal aortic aneurysm repair, women of child-bearing potential without contraception, inability to undergo magnetic resonance or computed tomography scanning, life expectancy of <2 years, and those with any form of collagen-vascular disease.