18F-Sodium Fluoride Uptake in Abdominal Aortic Aneurysms The SoFIA3 Study

BACKGROUND Fluorine-18-sodium fluoride (F-18-NaF) uptake is a marker of active vascular calcification associated with high-risk atherosclerotic plaque. OBJECTIVES In patients with abdominal aortic aneurysm (AAA), the authors assessed whether F-18-NaF positron emission tomography (PET) and computed tomography (CT) predicts AAA growth and clinical outcomes. METHODS In prospective case-control (n = 20 per group) and longitudinal cohort (n = 72) studies, patients with AAA (aortic diameter >40 mm) and control subjects (aortic diameter < 30 mm) underwent abdominal ultrasound, F-18-NaF PET-CT, CT angiography, and calcium scoring. Clinical endpoints were aneurysm expansion and the composite of AAA repair or rupture. RESULTS Fluorine-18-NaF uptake was increased in AAA compared with nonaneurysmal regions within the same aorta (p = 0.004) and aortas of control subjects (p = 0.023). Histology and micro-PET-CT demonstrated that 1(8F)-NaF uptake localized to areas of aneurysm disease and active calcification. In 72 patients within the longitudinal cohort study (mean age 73 +/- 7 years, 85% men, baseline aneurysm diameter 48.8 +/- 7.7 mm), there were 19 aneurysm repairs (26.4%) and 3 ruptures (4.2%) after 510 +/- 196 days. Aneurysms in the highest tertile of F-18-NaF uptake expanded 2.5 +/- more rapidly than those in the lowest tertile (3.10 [interquartile range (IQR): 2.34 to 5.92 mm/year] vs. 1.24 [IQR: 0.52 to 2.92 mm/year]; p = 0.008) and were nearly 3x as likely to experience AAA repair or rupture (15.3% vs. 5.6%; log-rank p = 0.043). CONCLUSIONS Fluorine-18-NaF PET-CT is a novel and promising approach to the identification of disease activity in patients with AAA and is an additive predictor of aneurysm growth and future clinical events. (Sodium Fluoride Imaging of Abdominal Aortic Aneurysms [SoFIA3]; NCT02229006; Magnetic Resonance Imaging [MRI] for Abdominal Aortic Aneurysms to Predict Rupture or Surgery: The MA3RS Trial; ISRCTN76413758) (J Am Coll Cardiol 2018; 71: 513-23) (c) 2018 The Authors. Published by Elsevier on behalf of the American College of Cardiology Foundation.