Association Between Vascular 18F-Fluorodeoxyglucose Uptake at Diagnosis and Change in Aortic Dimensions in Giant Cell Arteritis A Cohort Study

Background: Previous studies have shown that patients with giant cell arteritis (GCA) who have vascular F-18-fluorodeoxyglucose (FDG) uptake at diagnosis are at increased risk for thoracic aortic complications.Objective: To measure the association between vascular FDG uptake at diagnosis and the change in aortic dimensions.Design: Prospective cohort study.Setting: University Hospitals Leuven.Patients: 106 patients with GCA and FDG positron emission tomography (PET) imaging 3 days or less after initiation of glucocorticoids.Measurements: Patients had PET and computed tomography (CT) imaging at diagnosis and CT imaging yearly for a maximum of 10 years. The PET scans were scored 0 to 3 in 7 vascular areas and summed to a total vascular score (TVS). The PET scan results were positive when FDG uptake was grade 2 or greater in any large vessel. The association between vascular FDG uptake and aortic dimensions was estimated by linear mixed-effects models with random intercept and slope.Results: When compared with patients with a negative PET scan result, those with a positive scan result had a greater increase in the diameter of the ascending aorta (difference in 5-year progression, 1.58 mm [95% CI, 0.41 to 2.74 mm]), the diameter of the descending aorta (1.32 mm [CI, 0.38 to 2.26 mm]), and the volume of the thoracic aorta (20.5 cm(3) [CI, 4.5 to 36.5 cm(3)]). These thoracic aortic dimensions were also positively associated with TVS. Patients with a positive PET scan result had a higher risk for thoracic aortic aneurysms (adjusted hazard ratio, 10.21 [CI, 1.25 to 83.3]).Limitation: The lengthy inclusion and follow-up period resulted in missing data and the use of different PET machines.Conclusion: Higher TVS was associated with greater yearly increase in thoracic aortic dimensions. Performing PET imaging at diagnosis may help to estimate the risk for aortic aneurysm formation.Primary Funding Source: None.

Automated summary

This study aimed to measure the association between vascular FDG uptake at diagnosis and the change in aortic dimensions in patients with giant cell arteritis (GCA). The results showed that patients with positive FDG uptake had a greater increase in aortic dimensions and were at a higher risk for thoracic aortic aneurysms. The study suggests that performing PET imaging at diagnosis can help estimate the risk for aortic aneurysm formation.