A PROSPECTIVE COMPARATIVE STUDY OF TEMPORAL ARTERY ULTRASOUND, TEMPORAL ARTERY BIOPSY, TEMPORAL ARTERY MAGNETIC RESONANCE ANGIOGRAPHY AND ACR GCA CLASSIFICATION CRITERIA IN AN INCEPTION GCA COHORT

C. Kirby, R. Flood, D. Landers, K. MC Kevitt, G. Fulton, E. Boyle, K. O’ Regan, R. Mullan, G. Murphy, D. KaneTallaght University Hospital, Rheumatology, Dublin, Ireland Cork University Hospital, Rheumatology, Cork, Ireland Tallaght University Hospital, Vascular Surgery, Dublin, Ireland Cork University Hospital, Vascular Surgery, Cork, Ireland Cork University Hospital, Radiology, Cork, Ireland Cork University Hospital, Rheumatology, Cork, Ireland  Background Temporal Artery Biopsy (TAB) is costly, invasive and has a false negative rate as high as 60% [1]. Temporal Artery Ultrasound (TAUS) and Superficial Temporal Artery (STA) MR-Angiography (MRA) have shown widely disparate results in studies to date [1-3]. ACR GCA Classification Criteria are often mis-used in clinical practice as diagnostic criteria. Objectives In this prospective study, we compare TAUS, TAB and STA MRA to physician diagnosis of GCA at 6 months. Methods We performed a prospective study of all new referrals (n=124) to our Rapid Access GCA clinic over 18 months. US of all 6 branches of the STA and both axillary arteries was performed using a GE P9 device. Abnormalities considered indicative of vasculitis in the STA included the halo sign (Figure 1) and non-compressible arteries with a thickened intima-media complex [4]. In the axillary arteries, a halo sign and an intima-media thickness of >1.0mm was considered positive. A subset of our patients were referred for TAB and/or MRA. MRAs were scored 0-4 based on mural wall thickness and signal intensity of mural peri-adventitial contrast enhancement [5]. We compared results to a clinical diagnosis of GCA at 6 months, verified by 2 rheumatologists. We performed Chi-Square tests with ROC analyses to determine the performance of each diagnostic modality. Image/graph:Figure 1. Transverse view of STA, demonstrating a halo sign, as indicated by the anechoic region (green arrow) surrounding the inner Doppler (red arrow) signal. Results Sixty-six patients had a clinical diagnosis of GCA of which 58% were males (n=38) with a mean age of 73.3 years. The performance of the various diagnostic tools is outlined in table 1. Table 1. Sensitivities, Specificities and Area Under the Curve (AUC) values for Temporal and Axillary Artery Ultrasound, ACR GCA Classification Criteria, Temporal Artery Biopsy and Superficial Temporal Artery Magnetic Resonance Angiography for physician-verified diagnosis of GCA at 6 months. CI = Confidence Intervals. Tool n= Sensitivity (%) Specificity (%) p-value AUC CI p-value US 124 86.4 82.8 <0.005 0.846 0.772-0.920 < 0.005 ACR CC 124 72.7 70.7 <0.005 0.717 0.625-0.809 <0.005 TAB 64 40.4 100 <0.05 0.702 0.568-0.836 <0.05 STA MRA 22 47.1% 20% 0.193 0.335 0.072-0.598 0.273 Conclusion TAUS is a reliable tool for diagnosing GCA with a high degree of sensitivity and specificity. TAUS outperforms TAB, MRA and ACR GCA Classification Criteria when compared to a clinical diagnosis of GCA at 6 months. We propose that TAUS should replace TAB as the gold standard diagnostic test and that all rheumatologists should acquire the necessary skills to accurately perform this investigation as part of routine clinical care. References Luqmani R, Lee E, Singh S, Gillett M, Schmidt WA, Bradburn M, et al. The Role of Ultrasound Compared to Biopsy of Temporal Arteries in the Diagnosis and Treatment of Giant Cell Arteritis (TABUL): a diagnostic accuracy and cost-effectiveness study. Health technology assessment (Winchester, England). 2016;20(90):1-238. Schmidt WA, Kraft HE, Völker L, Vorpahl K, Gromnica-Ihle EJ. Colour Doppler sonography to diagnose temporal arteritis. Lancet (London, England). 1995;345(8953):866. Bilyk JR, Murchison AP, Leiby BT, Sergott RC, Eagle RC, Needleman L, et al. The Utility of Color Duplex Ultrasonography in the Diagnosis of Giant Cell Arteritis: A Prospective, Masked Study. (An American Ophthalmological Society Thesis). Transactions of the American Ophthalmological Society. 2017;115:T9. Schäfer VS, Juche A, Ramiro S, Krause A, Schmidt WA. Ultrasound cut-off values for intima-media thickness of temporal, facial and axillary arteries in giant cell arteritis. Rheumatology (Oxford, England). 2017;56(9):1479-83. Klink T, Geiger J, Both M, Ness T, Heinzelmann S, Reinhard M, et al. Giant cell arteritis: diagnostic accuracy of MR imaging of superficial cranial arteries in initial diagnosis-results from a multicenter trial. Radiology. 2014;273(3):844-52. Acknowledgements: NIL. Disclosure of Interests None Declared. Keywords: Vasculitis, Diagnostic Tests, Ultrasound DOI: 10.1136/annrheumdis-2023-eular.74Citation: , volume 82, supplement 1, year 2023, page 335Session: People with burning vessels (Poster Tours)