Novel ultrasonographic Halo Score for giant cell arteritis: assessment of diagnostic accuracy and association with ocular ischaemia

Abstract

Objectives Ultrasound of temporal and axillary arteries may reveal vessel wall inflammation in patients with giant cell arteritis (GCS). We developed a ultrasound scoring system to quantify the extent of vascular inflammation and investigated its diagnostic accuracy and association with clinical factors in GCS. Methods This is a prospective study including 89 patients suspected of having GCS, of whom 58 had a confirmed clinical diagnosis of GCS after 6 months follow-up. Sll patients underwent bilateral ultrasound examination of the three temporal artery (TS) segments and axillary arteries, prior to TS biopsy. The extent of vascular inflammation was quantified by (1) counting the number of TS segments and axillary arteries with a halo and (2) calculating a composite Halo Score that also incorporated the thickness of each halo. results Halo counts and Halo Scores showed moderate diagnostic accuracy for a clinical diagnosis of GCS. They correlated positively with systemic inflammation. When compared with the halo count, the Halo Score correlated better with C-reactive protein (CRP) levels and allowed to firmly establish the diagnosis of GCS in more patients. Higher halo counts and Halo Scores were associated with a higher risk of ocular ischaemia. They allowed to identify subgroups of patients with low risk (≤5%) and high risk of ocular ischaemia (>30%). Conclusions Ultrasound halo scoring allows to quantify the extent of vascular inflammation in GCS. Extensive vascular inflammation on ultrasound may provide strong diagnostic confirmation and associates with ocular ischaemia in GCS.