Pos0217 association Between Vascular FDG Uptake and Aortic Dimensions in Giant Cell Arteritis: A Prospective Study

Abstract

BackgroundPatients with giant cell arteritis (GCA) have an increased risk of developing aortic aneurysms. Retrospective studies have shown that18F-fluorodeoxyglucose (FDG) uptake in large vessels at diagnosis increases the risk of developing aortic complications during follow-up.ObjectivesTo prospectively evaluate the association between vascular FDG uptake at diagnosis and the evolution of aortic diameter and volume in patients with GCA.MethodsGCA patients who had FDG positron emission tomography (PET) imaging at diagnosis within 3 days of initiation of glucocorticoids and who were prospectively followed for at least 2 years were included. PET scans were visually scored (0-3) at 7 vascular areas and a total vascular score (TVS) was calculated, ranging from 0 to 21. Patients underwent a computed tomography (CT) scan at diagnosis and yearly thereafter for a maximum of 10 years. The association between vascular FDG uptake and aortic diameter and volume was estimated by linear mixed effect models with random intercept and slope adjusted for age, sex, cardiovascular risk factors, CT or PET/CT scan and intravenous contrast. The ascending aorta, aortic arch, and descending aorta were considered aneurysmatic when the diameter was ≥45, ≥40, and ≥35 mm, respectively.ResultsHundred patients (mean age 70 years, 68% females) were included, of which 74 patients had FDG uptake ≥2 in any large vessel, 60 in the thoracic aorta and 49 in the abdominal aorta. Median follow-up was 80 months (IQR 47-110). The increase in ascending and descending aortic diameter and in thoracic aortic volume was higher in patients with vascular FDG uptake ≥2 compared to those without (Table 1). This increase was also significantly associated with TVS (Figure 1). FDG uptake was not associated with an increase in abdominal aortic diameter nor volume. Thoracic aortic aneurysms were more frequently observed in patients with thoracic aortic FDG uptake (27% versus 10%, aOR 6.6, 95%-CI 1.8-31.0, p=0.009) with a median time since diagnosis of 40 months (IQR 18-61). Two patients with high TVS (15 and 16) needed surgery for thoracic aortic aneurysm.ConclusionThoracic aortic FDG uptake at diagnosis is an independent risk factor for developing thoracic aortic aneurysm in GCA patients. Higher TVS was associated with greater yearly increase in thoracic aortic volume and diameter. Follow-up of aortic dimensions may be necessary in these patients.Table 1.Evolution of the aortic diameter (in mm) and volume (in cm³) per year in patients with (PET positive) and without (PET negative) vascular FDG uptake ≥2FDG uptake ≥2 in any large vesselRegression coefficient (95% CI)p-valuePET negativePET positiveVolume of thoracic aorta2.40 (-0.40 – 5.21)6.80 (5.09 – 8.53)0.008Volume of abdominal aorta0.28 (-0.48 – 1.04)0.12 (-0.33 – 0.57)0.72Diameter of thoracic aorta ◦ Ascending aorta0.10 (-0.10 – 0.30)0.41 (0.29 – 0.53)0.009 ◦ Aortic arch0.21 (0.05 – 0.37)0.35 (0.25 – 0.45)0.14 ◦ Descending aorta0.11 (-0.06 – 0.27)0.34 (0.24 – 0.44)0.01Diameter of abdominal aorta ◦ Suprarenal aorta0.07 (-0.04 – 0.17)0.11 (0.04 – 0.17)0.51 ◦ Juxtarenal aorta0.14 (0.03 – 0.25)0.14 (0.07 – 0.21)0.98 ◦ Infrarenal aorta0.15 (0.07 – 0.23)0.08 (0.03 – 0.12)0.11FDG uptake ≥2 in thoracic aortaRegression coefficient (95% CI)p-valuePET negativePET positiveVolume of thoracic aorta3.13 (0.86 – 5.43)7.32 (5.44 – 9.22)0.005Diameter of thoracic aorta ◦ Ascending aorta0.15 (-0.02 – 0.31)0.45 (0.31 – 0.58)0.005 ◦ Aortic arch0.22 (0.09 – 0.35)0.37 (0.27 – 0.48)0.07 ◦ Descending aorta0.18 (0.05 – 0.32)0.35 (0.23 – 0.46)0.06FDG uptake ≥2 in abdominal aortaRegression coefficient (95% CI)p-valuePET negativePET positiveVolume of abdominal aorta0.08 (-0.45 – 0.61)0.23 (-0.33 – 0.78)0.69Diameter of abdominal aorta ◦ Suprarenal aorta0.07 (-0.00 – 0.14)0.12 (0.05 – 0.20)0.32 ◦ Juxtarenal aorta0.13 (0.05 – 0.20)0.15 (0.07 – 0.23)0.70 ◦ Infrarenal aorta0.12 (0.07 – 0.18)0.06 (0.00 – 0.12)0.12Figure 1.Association between TVS and (A) volume of thoracic aorta, (B) diameter of ascending aorta and (C) diameter of descending aortaREFERENCES:NIL.Acknowledgements:NIL.Disclosure of InterestsNone Declared.