POS0273 THE ROLE OF FACIAL, OCCIPITAL, SUBCLAVIAN AND CAROTID ARTERIES ULTRASOUND IN THE DIAGNOSTIC ASSESSMENT OF GIANT CELL ARTERITIS

BackgroundGiant cell arteritis (GCA) is the most common form of primary systemic vasculitis in patients aged >50 years. It predominantly affects the cranial arteries; however, extra-cranial disease involving the aorta and its major branches can also be present. Currently, ultrasound of the temporal (TA) and axillary (AX) arteries is the first imaging modality recommended in patients with suspected predominantly cranial GCA. Nevertheless, other arteries such as facial (FA), occipital (OC), subclavian (SC), and common carotid (CC) arteries can also show vasculitic changes on ultrasound. However, there are still conflicting data to support the inclusion of these arteries in the routine ultrasound assessment of patients with suspected GCA.ObjectivesTo assess the value of adding the evaluation of the FAs, OCs, SCs and CCs in the ultrasonographic diagnosis of patients with GCA.MethodsSingle-center observational retrospective study, using data from patients diagnosed with GCA registered at the Rheumatic Diseases Portuguese Registry (Reuma.pt). All patients underwent ultrasound of the TAs and AXs ± FAs, OCs, SCs or CCs at the time of diagnosis. The halo sign was considered a positive ultrasonographic finding for GCA. Only patients with the presence of halo sign in at least one of the arterial segments evaluated were included. Binary logistic regression modelling was performed to explore associations between the presence of halo sign in different arterial segments.ResultsWe included 84 patients, 57 (67.9%) females, with a mean ± standard deviation age at diagnosis of 75.6 ± 8.8 years. Halo sign was found in the TAs of 66/84 (78.6%) patients, AXs of 40/84 (47.6%) patients, FAs of 37/74 (50.0%) patients, OCs of 15/61 (24.6%) patients, SCs of 30/49 (61.2%) patients and CCs of 13/60 (21.7%) patients. Of the 18/84 patients with GCA without the presence of TA halo, 17/18 (94.4%) showed halo in the AXs, 1/18 (5.6%) in the FAs, 3/18 (16.7%) in the OCs, 15/17 (88.2%) in the SCs and 6/16 (37.5%) in the CCs. Of the 44/84 patients with GCA without the presence of AX halo, 43/44 (97.7%) showed halo in the TAs, 24/39 (61.5%) in the FAs, 12/32 (37.5%) in the OCs, 4/18 (22.2%) in the SCs and 3/33 (9.1%) in the CCs. A total of 83/84 (98.8%) patients had halo sign on the ultrasound of either the TA or AX arteries. The patient with normal TA and AX ultrasound had the presence of halo sign in the SCs. Table 1 shows the proportion of patients with positive TA and AX ultrasounds according to the presence of halo in the FA, OC, SC or CC arteries. Patients with involvement of the cranial arteries were more likely to have a TA halo (FA: OR 30.6, 95%CI 3.8-247.3; OC: OR not applicable) and less likely to have an AX halo (FA: OR 0.37, 95%CI 0.14-0.95; OC: OR 0.19, 95%CI 0.05-0.77). As opposed to patients with involvement of the extra-cranial arteries in whom the halo sign was more frequently found in the AXs (SC: OR 18.2, 95%CI 4.2-78.9; CC: OR 5.9, 95%CI 1.4-24.4) but not in the TAs (SC: OR 0.12, 95%CI 0.02-0.60; CC: OR 0.32, 95%CI 0.09-1.15).Table 1.Differences in the presence of halo sign in the temporal and axillary arteries according to the arterial segment affected.Arterial segment with haloTemporal arteries with haloAxillary arteries with haloFacial arteries (n=37)36/37 (97.3%)13/37 (35.1%)Occipital arteries (n=15)15/15 (100.0%)3/15 (20.0%)Subclavian arteries (n=30)15/30 (50.0%)26/30 (86.7%)Common carotid arteries (n=13)7/13 (53.8%)10/13 (76.9%)ConclusionOur results support the need to assess both TAs and AXs in patients with suspected GCA, resulting in a diagnostic sensitivity of 99%. Only by adding the evaluation of the SCs to the already recommended TAs and AXs increased the diagnostic sensitivity of ultrasound to 100%. All patients with a positive FA, OC or CC ultrasound for GCA also showed a halo sign in either the TAs or AXs. Hence, the additional assessment of these arteries did not improve the diagnostic yield of ultrasound and, therefore, should not be recommended in routine practice.Disclosure of InterestsNone declared