Sodium Fluoride Imaging of Abdominal Aortic Aneurysms

SoFIA3: Sodium Fluoride Imaging (18F-NaF PET-CT) in Abdominal Aortic Aneurysms

The purpose of this study is to determine whether Sodium Fluoride imaging (using Positron Emission Tomography-Computed Tomography - PET-CT) is able to help predict the rate of abdominal aortic aneurysm expansion.

Ruptured abdominal aortic aneurysms (AAAs) have a 90% mortality rate but there are currently no accurate methods of establishing the risk of rupture for an individual patient with an asymptomatic AAA. In vascular disease, microcalcification occurs in response to necrotic inflammation. Using computed tomography and positron emission tomography (PET-CT), early micro calcification can be identified using uptake of the radiotracer 18F-sodium fluoride. This can identify high risk-lesions in the aorta, coronary and carotid arteries, and appears to be indicative of necrotic and heavily inflamed tissue. The study investigators therefore propose to evaluate the ability of 18F-sodium fluoride to identify regions of necrotic inflammation in AAA and predict AAA expansion. The study investigators will explore its value as part of an ongoing clinical trial assessing the identification of macrophage activity using magnetic resonance imaging - the MA3RS Study (ISRCTN76413758). Patients already enrolled in the MA3RS Study will be recruited for the SoFIA3 study. Control patients with a normal calibre aorta will be recruited from the National AAA Screening Programme.

Inclusion Criteria (AAA patients):

• Patients already enrolled in the MA3RS study (ISRCTN76413758)
• Patients with abdominal aortic aneurysm with AP diameter >40 mm on ultrasound
• >50 years of age

Inclusion Criteria (control patients):

• Patients with abdominal aorta with AP diameter <30 mm on ultrasound
• >50 years of age

Exclusion Criteria:

• Patients expected to undergo imminent AAA repair
• Patients who refuse or are unable to give informed consent
• Women of child-bearing potential without contraception
• Patients who are unable to undergo PET-CT scan
• Patients with collagen vascular disease
• Intercurrent illness, malignancy or comorbidity with life expectancy <1 year
• Renal dysfunction (eGFR <30ml/min/1.73m2)
• Contraindication to PET-CT or CTA
• Iodine allergy