Vascular FDG Uptake and Aortic Dimension Change in Giant Cell Arteritis

Quick Takes

  • In a single-center, prospective cohort study, patients with vascular FDG uptake on PET at the time of giant cell arteritis (GCA) diagnosis had a greater subsequent increase in ascending and descending aorta diameters and thoracic aortic volume.
  • There was an approximately 10-fold higher incident risk of thoracic aortic aneurysm among patients with a positive FDG-PET compared to those with a negative FDG-PET.

Study Questions:

Is there an association between vascular 18F-fluorodeoxyglucose (FDG) uptake at the time of giant cell arteritis (GCA) diagnosis and subsequent change in aortic dimensions?


In a prospective cohort study performed at University Hospitals Leuven, 106 patients with GCA and FDG positron emission tomography (PET) imaging performed ≤3 days after the initiation of glucocorticoids underwent thoracic and abdominal aortic computed tomography (CT) imaging at diagnosis and yearly for a maximum of 10 years. PET scans were scored 0-3 (0, no FDG uptake; 1, minimal; 2, clearly increased; 3, marked) in seven vascular regions (thoracic and abdominal aorta; subclavian, axillary, carotid, iliac, and femoral arteries), and summed to a total vascular score (TVS). An FDG uptake grade ≥2 in any large vessel was used to define a positive PET scan. The association between vascular FDG uptake and aortic dimensions was estimated by linear mixed-effects models with random intercept and slope.


Of 106 patients (mean age, 70 years), 75 (71%) had a PET scan positive for FDG uptake (median TVS 14 [IQR, 6-16] compared to median TVS 0 [IQR, 0-1] in the PET-negative group). The median follow-up to the last CT scan was 6.1 years (IQR, 3.0-8.6 years). Compared to patients with a negative PET scan, those with a positive scan had a greater increase in the diameter of the ascending aorta (difference in 5-year progression, 1.58 mm [95% CI, 0.41-2.74 mm]), the diameter of the descending aorta (1.32 mm [95% CI, 0.38-2.26 mm]), and the volume of the thoracic aorta (20.5 cm3 [95% CI, 4.5-36.5 cm3]); thoracic aortic dimensions were positively associated with TVS. Aortic aneurysm developed in 23 patients at a median interval of 35 months (IQR, 14-60 months) after GCA diagnosis. The incident risk of thoracic aortic aneurysm was higher among patients with an FDG-positive PET scan (adjusted hazard ratio, 10.21 [95% CI, 1.25-83.3]).


Higher TVS was associated with a greater yearly increase in thoracic aortic dimensions. The authors conclude that performing PET imaging at GCA diagnosis may help to estimate the risk for aortic aneurysm formation.


Aortitis is present in approximately 45-65% of patients at the time of GCA diagnosis, and retrospective studies have associated intense aortic inflammation on PET with an increased risk of subsequent aortic dilation. This relatively large, single-center cohort study found that patients with a PET scan positive for vascular FDG uptake at the time of GCA diagnosis had a greater increase in ascending and descending thoracic aortic dimensions, with an association between thoracic aortic dimensions and the extent of vascular involvement quantified by TVS; and confirmed that the incident risk of thoracic aortic aneurysm was higher among patients with a positive FDG-PET.

The 2022 American College of Cardiology/American Heart Association Guideline for the Diagnosis and Management of Aortic Disease (Isselbacher EM, et al., J Am Coll Cardiol 2022;80:e223-e393) recommends annual surveillance imaging of the aorta in patients with GCA and aortic involvement who are in remission (Class IIa, Level of Evidence C-EO). Data from this study might help prospectively identify patients at risk of future aortic involvement, and, if confirmed on a larger scale, could help tailor follow-up aortic imaging recommendations.

Clinical Topics: Cardiac Surgery, Noninvasive Imaging, Vascular Medicine, Aortic Surgery, Computed Tomography, Nuclear Imaging

Keywords: Aortic Aneurysm, Fluorodeoxyglucose F18, Giant Cell Arteritis, Positron-Emission Tomography, Vascular Diseases

< Back to Listings