Ab1320 Doppler Ultrasound in Giant Cell Arteritis: Which Territories Should We Explore? A Retrospective Analysis of a Single Center Experience

Background: Giant cell arteritis (CGA) can be a disabling disease, with permanent vision loss as a severe complication in untreated patients. The use of temporal and axillary Doppler ultrasound (DUS) has changed how we evaluate our patients, reducing the need for invasive techniques such as temporal artery biopsy (TAB). Objectives: The aim of this study is to describe the use of DUS performed by internal medicine physicians to diagnose GCA. Methods: Observational retrospective study that included all patients evaluated at a DUS clinic under a GCA diagnosis between 05/21 and 05/23. Information about symptoms, blood tests, DUS and PET/CT was registered. Patients were classified as low GCA suspicion, high GCA suspicion, polymyalgia rheumatica (PMR) diagnosis. DUS was considered positive if a hypoechoic arterial wall thickening was observed in temporal (TA), carotid (CA), vertebral (VA) or axillary (AxA) arteries. PET/CT was considered positive if vascular wall uptake was higher than liver uptake. Aorta, supraaortic branches and vertebral arteries (VA) were evaluated. A definite diagnosis was made if ACR/EULAR 2022 classification criteria were met. Analisis was performed by SPSS v20. Results are expressed as mean ± standard deviation or median (quartile 1 – quartile 3). Univariate analysis was initially performed, and significance was set at pResults: We evaluated 119 patients, 78 (65.5%) women, with a medium age of 81±15 years. 52 patients (43.7%) met ACR/EULAR 2022 criteria for GCA diagnosis. DUS was positive in 45 (37.8%) patients: 5 (25%) in the PMR group, 14 (23%) in the low probability and 25 (65.8%) in the high probability group. The distribution of DUS findings included an abnormality in 28 TA, 5 CA, 4 VA and 12 AxA. 2 patients had a TA and AxA abnormality. One patient with CA involvement showed a TA halo sign. Four patients had VA involvement, 3 of them with an abnormal TA. Slope sign was observed in 5 AxA and in 1 carotid artery and 2 of them were false positive (atherosclerosis). Thirty-six (38.9%) patients had positive PET/CT. Positive DUS and PET/CT were present in 24 patients. Sixteen patients had a pathological DUS with a normal PET/CT and 12 patients had a positive PET/CT with normal DUS. If TA and AxA were just considered, DUS had a sensitivity (Sn) of 73.1%, specificity (Sp) of 89.6%, a positive predictive value of 86% and negative of 82% with Area Under the Curve (AUC) 0.82 (95% CI 0.74-0.91) in ROC curve. When TA DUS was evaluated, we found a Sn 52% and Sp 97.9%. PET/CT showed a Sn 56.55 and a Sp 79.2% with an AUC 0.68 (95% CI 0.57 - 0.79). Univariate analysis of clinical data is shown in Table 1. Independent risk factors according to logistic regression analysis were erythrocyte sedimentation rate (Exp (B) 1,01; p=0,038), vision loss (Exp (B) 2.93; p= 0.047), jaw claudication (Exp (B) 4.65; p= 0.014) and age (Exp (B) 1.07; p= 0.013). Conclusion: TA and AxA DUS increase sensitivity with a slight decrease of specificity in GCA diagnosis. CA and VA DUS could be useful to increase diagnostic yield in GCA. The slope sign had a high rate of false positives (30%). PET/CT had less sensitivity and less specificity than DUS in all levels of clinical suspicion. Ageing, jaw claudication, loss of vision and increased ESR were found to be independent factors that can predict the presence of a pathological DUS. REFERENCES: NIL. Acknowledgements: To my collegues, who encouraged me to go deeper in systemic diseases. Disclosure of Interests: None declared.