Background Ultrasound (US) has been used in the diagnosis of GCA since the early 90's, however it has not yet superseded temporal artery biopsy as a diagnostic test, either in practice or in criteria for diagnosis. This may reflect poor consistency of the scanning technique, due to the lack of a standardised scanning protocol. We have developed a standardised protocol which was implemented in a prospective study of 431 patients with suspected GCA (Temporal Artery Biopsy versus Ultrasound, TABUL).
Methods A detailed scanning protocol was developed, with a Case Report Form (CRF) recording segments of the temporal arteries (common, parietal, frontal proximal and frontal distal) as well as the axillary arteries. The CRF recorded details of each segment asking the sonographer to establish whether there were features within the scan consistent with a diagnosis of GCA. We acquired video and static images for each patient to ensure accuracy of findings. The sonographer measured and documented halo diameter and length, pulse Doppler measurements prior to and within a stenosis, and assessed arterial occlusion, recording longitudinal and transverse images to support their findings. This protocol was consistently used throughout the study, including all training cases. Participating sites were required to have a study sonographer trained proficiently in utilising the scanning protocol. This included scanning at least 10 healthy controls and completion of an online test in order to demonstrate, to an expert panel, their ability to scan a patient with active GCA.
Results 22 sites completed the US scanning protocol in 6.7 months [range 0.2–16.4 months]. 295 control cases were scanned across the 22 sites (average of 13.4 controls per site). 39 sonographers passed the on-line test (pass mark >75%) with 2 attempts [range 1-4]). 22 sonographers successfully scanned an active GCA patient, which were reviewed by the expert panel. The longest delay in completing the training was due to difficulty in recruiting a patient with active GCA.
We have established a bank of over 850 consistently recorded US images with detailed numerical data from the CRF (Halo measurements and stenosis values) and a bank of over 230 correlating biopsy cases to date. Cases can be viewed with clinical history, biopsy and US images, creating a comprehensive case review.
Conclusions Quality and accuracy are imperative for the clinical use of ultrasound data in diagnostic techniques. We have developed an effective protocol, including training, which ensures consistency and proficiency in scanning. The CRF can be adapted and extended to allow for additional artery assessment, including carotid, vertebral and subclavian, extending the value of the structured protocol. We recommend the TABUL study scanning protocol as the standard approach for diagnosis of GCA using ultrasound.
Acknowledgements The Temporal Artery Biopsy vs. Ultrasound (TABUL) study is funded by the National Institute for Health Research Health Technology Assessment (NIHR HTA Ref No. 08/64/01).
Disclosure of Interest None declared
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