Ultrasonography led multimodal diagnostic pathway for giant cell arteritis

Objectives To establish the sensitivity and negative predictive value of a multimodal pathway incorporating ultrasonography, 18-fluorodeoxyglucose labelled positron emission tomography computed tomography and temporal artery biopsy for the diagnosis of giant cell arteritis. Methods 1000 consecutive referrals for a new diagnosis of giant cell arteritis were analysed. All patients had a protocolized examination. Patients with a negative ultrasonography and a C-reactive protein of ≥ 20 mg/l received an extended ultrasound examination. If that was negative, and there was no other explanation for their presentation, a second test in the form of either a temporal artery biopsy or an 18-fluorodeoxyglucose labelled positron emission tomography computed tomography was offered. We calculated the sensitivity and negative predictive value of the interventions for diagnosing giant cell arteritis. Results 279/1000 patients had positive ultrasonography for giant cell arteritis. 202 had bilateral superficial temporal arterial involvement. Ultrasonography of the axillary artery and other head/neck arteries increased the yield by 53 and 24 patients respectively. 181 patients were referred for a second test. 24/139 temporal artery biopsies and 7/42 18-fluorodeoxyglucose labelled positron emission tomography computed tomography scans were positive. The sensitivity and negative predictive value rise from 62.3% and 84.7% respectively for imaging superficial temporal arteries alone, to 95.7% and 98.0% respectively for extended ultrasonography plus a second test. Conclusions This is the first real world evidence of the utility of ultrasonography for the diagnosis of giant cell arteritis as part of a multimodal diagnostic pathway.