Aortic dilatation in patients with large vessel vasculitis: A longitudinal case control study using PET/CT

To evaluate aortic diameter and predictors of aortic dilatation using ¹⁸FDG-PET/CT in a longitudinally followed cohort of patients with large vessel vasculitis (LVV) compared with controls.

All consecutive patients with LVV who underwent at least 2 PET/CT scans between January 2008 and May 2015 were included. The first and last PET/CT study was evaluated by a radiologist and a nuclear medicine physician. Diameter and FDG uptake of the aorta was measured at 4 different levels: ascending, descending thoracic, suprarenal and infrarenal abdominal aorta. Twenty-nine age- and sex-matched patients with lymphoma who underwent at least 2 PET/CT scans in the same time interval were selected as controls.

93 patients with LVV were included in the study. In the time interval between first and last PET/CT study (median time 31 months), the diameter of the ascending, descending thoracic and suprarenal abdominal aorta significantly increased in LVV patients but not in controls. At last PET/CT, patients with LVV compared with controls had higher diameter of ascending [35.41 (5.54) vs 32.97 (4.11) mm, p = 0.029], descending thoracic [28.42 (4.82) vs 25.72 (3.55) mm, p = 0.007] and suprarenal abdominal aorta, mean [25.34 (7.01) vs 22.16 (3.26) mm, p = 0.005] and more frequently had aortic dilatation [19% vs 3%, p = 0.023]. Significant predictors of aortic dilatation were male sex [OR 7.27, p = 0.001] and, only for GCA, hypertension [OR 6.30, p = 0.031]. Finally, GCA patients with aortic FDG uptake grade 3 at first PET/CT, compared to those with aortic FDG uptake ≤2, had significantly higher aortic diameter.

Patients with LVV are at increased risk of aortic dilatation compared with age- and sex-matched controls. Significant predictors of aortic dilatation are male sex and, only for GCA, hypertension. GCA patients with aortic FDG uptake grade 3 are at increased risk of aortic dilatation.