THU0444 Aortic dilatation in patients with large vessel vasculitis: a longitudinal case control study using positron emission tomography/computed tomography
Authors: F. Crescentini, F. Muratore, L. Spaggiari, G. Pazzola, L. Boiardi, N. Pipitone, C. Salvarani
Journal: Annals of the Rheumatic Diseases (2018)

<h3>Objectives</h3> To evaluate aortic diameter and predictors of aortic dilatation using FDG-PET/CT in a longitudinally followed cohort of patients with large vessel vasculitis (LVV) compared with controls. <h3>Methods</h3> 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 of each patient was independently evaluated by a radiologist and a nuclear medicine physician. The diameter of the aorta was measured at 3 different levels: ascending, descending thoracic and infrarenal aorta. Aortic dilation was defined as a diameter of &gt;4 cm in the ascending,≥4 cm in the descending thoracic and ≥3 cm in the infrarenal aorta. Aortic FDG uptake was graded at the same levels using a 0–3 semiquantitative scale and was reported as negative (score 0 or 1) or positive (score 2 and 3). Patients younger than 50 years at symptoms' onset were classified as Takayasu arteritis (TAK), while those older than 50 years as giant cell arteritis (GCA). 29 age- and sex-matched patients with lymphoma who underwent at least 2 PET/CT in the same time interval without evidence of aortic FDG uptake were selected as controls. <h3>Results</h3> 93 patients with LVV were included in the study. 53% of patients were newly-diagnosed; the remaining 47% had a median disease duration of 34 months. At first PET/CT, the mean (SD) diameter of descending thoracic aorta was significantly higher in LVV patients compared with controls [28.07 (4.40) vs 25.60 (3.59) mm, p=0.012]. At last PET/CT, after a median time of 31 months, patients with LVV compared with controls had higher diameter of ascending [35.41 (5.54) vs 32.97 (4.11) mm, p=0.029] and descending thoracic aorta [28.42 (4.82) vs 25.72 (3.55) mm, p=0.007] 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 the diameter of ascending [OR 2.03, p&lt;0.001], descending thoracic [OR 1.57, p&lt;0.001] and infrarenal [OR 1.25, p=0.005] aorta at first PET/CT study. Positive aortic FDG uptake, disease activity and elevated inflammatory markers at first PET/CT were not associated with an increased risk of aortic dilatation. The results remained unchanged when the analysis were restricted to the 48 newly-diagnosed LVV patients. According to age at symptoms onset, 56% of patients were classified as GCA and 44% as TAK. Compared with TAK, GCA patients had higher aortic diameter at all 3 levels evaluated in both first and last PET/CT study. However there were no differences in the proportion of patients with aortic dilatation (at last PET/CT 23% in GCA vs 15% in TAK, p=0.306). The results remained unchanged when the analysis were restricted to the newly-diagnosed patients. <h3>Conclusions</h3> Patients with large vessel vasculitis are at increased risk of aortic dilatation compared with age- and sex-matched controls. Significant predictors of aortic dilatation are male sex and aortic diameter at first imaging study. Positive aortic FDG uptake at first PET/CT is not associated with increased risk of aortic dilatation. <h3>Disclosure of Interest</h3> None declared