Background/Purpose: There is an increased use of vascular ultrasound (US) for diagnosing giant cell arteritis (GCA).  Consequently, extensive and structured training of ultrasonographers performing vascular ultrasound is required in order to ensure standardization of examination technique and machine settings to obtain reliable results. The primary aim of this study was to evaluate the results of a standardized training program for ultrasonographers in the diagnosis of temporal artery (TA) vasculitis in GCA.

Methods: Rheumatologists with long-standing experience in musculoskeletal US were extensively trained in the use of vascular US by a specific program. Initially participation  in the International  Workshop on US in Large Vessel Vasculitis and Polymyalgia Rheumatica in Kristiansand, Norway (5 hours theoretical and 10 hours supervised hands-on education) followed by a two day workshop in Denmark (6 hours of supervised hands-on trainings and 1 hour of image evaluation)with additional training and standardization of scanning technique and optimization of settings . Immediately after this training program a US study on patients suspected for GCA was initiated. Patients were examined with high-end US equipment with high resolution transducers, optimized vascular settings and standardized examination technique. After the US examination of TA, a temporal artery biopsy (TAB) was performed. Pictures and film clips of all three TA branches in two planes were recorded and evaluated by the performing sonographer and by a blinded expert. Detailed feedback on the US technique was given to the performing sonographer by the external expert.

US was considered positive in the presence of the halo sign (hypoechoic arterial wall swelling) and/or the presence of a positive compression-sign (arterial wall remaining visible upon compression with US transducer).

Results: During 12 months, 37 patients from three Danish Rheumatologic Departments  (Esbjerg, Glostrup, Silkeborg) suspected to have GCA were recruited. In 20 patients with a positive TAB for GCA, US was positive in all patients  according to both the performing sonographer and the blinded external expert.

In 15 patients with negative TAB, neither the performing sonographer, nor the external reader found signs of vasculitis. In one patient with a negative TAB, US showed vasculitis (both readers) and in one the local sonographer’s finding of US vasculitis was rejected by the blinded expert.

In total, 222 branches of TA were scanned and vasculitis changes were observed in 82 branches (expert) and in 80 branches (performing sonographer).  The inter-observer agreement between the performing sonographer and the blinded expert was excellent in all three centres/departments (Cohens kappa-coefficient: Esbjerg k=0.88, Glostrup k=0.90 and Silkeborg k=0.82).

Conclusion: Following an intense structured training program on vascular ultrasound using high quality equipment, we were able to obtain an excellent agreement between US of TA and subsequent TAB in patients suspected for GCA. Furthermore, an excellent interobserver agreement between the performing sonographers and the blinded expert reader were seen. This training set-up could be useful in the implementation of US for diagnosing GCA .

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/a-structured-and-extensive-training-program-on-vascular-ultrasound-results-in-an-excellent-agreement-between-ultrasound-and-temporal-artery-biopsy-in-the-diagnosis-of-giant-cell-arteritis/