FRI0641 THE ‘SLOPE SIGN’: A FEATURE OF LARGE VESSEL VASCULITIS?

Abstract

Background Ultrasonography in large vessel vasculitis (LVV) has become popular as a non-invasive, radiation-free, point of care examination that allows assessment of entire temporal and axillary vessels. EULAR recommends ultrasound as first line imaging of giant cell arteritis (GCA) and LVV (1) and polymyalgia rheumatica (PMR). Cranial and large vessels GCA (LV GCA) are considered the two sub types of the disease. Ultrasound in cranial GCA is well established, with the non-compressible halo of temporal arteries considered the key diagnostic finding. In LV GCA, increased intima-medial thickness (cut off >1.0 mm), is the preferred method of diagnosis. There are other causes of thickening of arterial wall, such as atherosclerosis. Atherosclerotic US changes in US scan are localized and discrete; however, at times it may be challenging to differentiate vasculitic from atherosclerotic changes. Objectives We describe the ‘Slope sign’ as a unique additional finding in US scan of axillary arteries in LV GCA. Ultrasound scan of the axillary arteries of all these patients showed increased intima-medial thickness (IMT) > cut off value of 1.0 mm. Here we report the study of the junctional transitional region between involved and uninvolved arteries in these patients. Methods Images of 28 patients, with confirmed LV GCA who attended a GCA/LVV clinic at Southend Hospital between 1st September 2018 and 18th January 2019, were reviewed. They were scanned with an Esaote MyLabTwice using a LA435 linear transducer (band width 12-18 MHz). The axillary arteries were assessed in the grey scale mode in the longitudinal axis using tissue harmonic imaging. LV GCA was confirmed with an IMT of 1.0 mms or above in all patients. Results We observed a sloping smooth transitional zone connecting involved and uninvolved arteries (the “slope sign”) in the ultrasound scan of axillary arteries in 24/28 patients with confirmed LV GCA. The remaining 4 patients did not have the transition zone imaged and therefore could not be assessed for presence of the ‘slope’ sign. Conclusion Presence of the ‘Slope sign’ in the ultrasound scan of the axillary arteries in patients with LVGCA, is a secondary confirmation alongside the abnormal IMT, of LV disease. Biologics therapy has reduced the utility of inflammatory markers in GCA and highlighted need for imaging in disease assessment (2). The ‘slope sign’ may not only differentiate increased IMT of LVV from atheroma but the area under the ‘slope’ could potentially be used to estimate disease extent. We suggest the ‘slope’ sign be included in axillary artery ultrasound scan protocols for all patients with suspected GCA and also for monitoring disease activity in LVGCA.