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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?
Methods:
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.
Results:
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]).
Conclusions:
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.
Perspective:
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
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