Aortic sodium [¹⁸F]fluoride uptake following endovascular aneurysm repair

Objective: In patients with abdominal aortic aneurysms, sodium [¹⁸F]fluoride positron emission tomography identifies aortic microcalcification and disease activity. Increased uptake is associated with aneurysm expansion and adverse clinical events. The effect of endovascular aneurysm repair (EVAR) on aortic disease activity and sodium [¹⁸F]fluoride uptake is unknown. This study aimed to compare aortic sodium [¹⁸F]fluoride uptake before and after treatment with EVAR.

Methods: In a preliminary proof-of-concept cohort study, preoperative and post-operative sodium [¹⁸F]fluoride positron emission tomography-computed tomography angiography was performed in patients with an infrarenal abdominal aortic aneurysm undergoing EVAR according to current guideline-directed size treatment thresholds. Regional aortic sodium [¹⁸F]fluoride uptake was assessed using aortic microcalcification activity (AMA): a summary measure of mean aortic sodium [¹⁸F]fluoride uptake.

Results: Ten participants were recruited (76±6 years) with a mean aortic diameter of 57±2 mm at time of EVAR. Mean time from EVAR to repeat scan was 62±21 months. Prior to EVAR, there was higher abdominal aortic AMA when compared with the thoracic aorta (AMA 1.88 vs 1.2; p<0.001). Following EVAR, sodium [¹⁸F]fluoride uptake was markedly reduced in the suprarenal (ΔAMA 0.62, p=0.03), neck (ΔAMA 0.72, p=0.02) and body of the aneurysm (ΔAMA 0.69, p=0.02) while it remained unchanged in the thoracic aorta (ΔAMA 0.11, p=0.41).

Conclusions: EVAR is associated with a reduction in AMA within the stented aortic segment. This suggests that EVAR can modify aortic disease activity and aortic sodium [¹⁸F]fluoride uptake is a promising non-invasive surrogate measure of aneurysm disease activity.