AB1297 CAN MICROVASCULAR HIGH FREQUENCY TEMPORAL ARTERY ULTRASOUND SCANNING ENHANCE THE DIAGNOSTIC/MONITORING AND PREDICTING THE PHENOTYPE OF CRANIAL GIANT CELL ARTERITIS (GCA)
Authors: M. H. Abu-Zaid, Y. El Miedany, M. Elgaafary, W. Elwakil, W. Hassan
Journal: Annals of the Rheumatic Diseases (2024)

<h3>Background:</h3> Ultrasound of temporal ± axillary arteries is recommended as the first imaging modality in patients with suspected predominantly cranial GCA. A non-compressible "Halo" sign and thickening of the intima media are the ultrasound findings most suggestive of GCA. <h3>Objectives:</h3> 1.To assess the utility of standardized high-resolution ultrasound scanning of the temporal artery for the diagnosis of GCA 2.To assess the potential role of microvascular imaging in predicting GCA phenotype and the patient's prognosis. <h3>Methods:</h3> Study design: This was a cross-sectional observational case-case study. Patients: GCA patients diagnosed according to the EULAR/ACR criteria. Retrospective analysis of consecutive newly diagnosed GCA patients who had ultrasound-confirmed GCA at baseline and underwent serial ultrasound evaluation of the temporal artery (TA) and axillary artery (AA) using Superb microvascular imaging (SMI)/ Microvascular Imaging (MVI) at fixed time points (baseline, 2-weeks, 4-weeks, then at 2-, 3-, 6-, 9- and 12-months). The number of segments with halo and maximum halo intima-media thickness (IMT) were recorded. Halo features at disease presentation and IMT and first relapse were compared. In addition, every patient was asked to complete a copy of the GCA-specific Patient Reported Outcome Measures (GCA-PROMs) questionnaire [1]. Disease activity score (GCA-DAS) [2] was assessed individually for all the patients at each point of clinical assessment. The association between the baseline US measures and the development of visual affection and patients' prognosis was also studied. Intra- and Inter-observer reliability of the US scanning was carried out. <h3>Results:</h3> In comparison to baseline measurements, at week-1 of starting therapy, there was significant difference in the IMT (p&lt; 0.05), whereas at week-2, there was significant mean difference in the number of segments with halo and the halo IMT (p&lt; 0.01), whereas there was significant difference at the AA in both measures by week-8. In the patients who sustained relapse, halo sign was recorded in 82% of the patients with first relapse of the disease relapses, however the mean of IMT was significantly lower (p&lt; 0.01) than the disease onset baseline measures, though remain significant (p&lt; 0.01) in comparison to the measures taken during remission. IMT correlated significantly (p&lt; 0.001) with the disease activity score (GCA-DAS), platelet count and CRP level at baseline. TA involvement without AA involvement was predictive of visual affection with a stronger association for those with bilateral halos (OR 8.892 (95% CI=1.316 to 81.741; p=0.02). Involvement of both TAs and AAs infers a significantly higher risk of relapse (10.627 (95% CI=1.846 to 91.682; p=0.01) and a more frequent requirement for steroid-sparing agents relative to those patients with either isolated cranial or isolated upper limb GCA. Interobserver agreement of 94–96% with mean kappa values of 0.89–0.94 (95% CI 0.79 to 0.96). <h3>Conclusion:</h3> US should be a standard first line investigation in routine clinical care of patients with suspected GCA with Temporal Artery biopsy perhaps reserved for those only having had a normal US in the context of a high pre-test probability. Temporal artery US is a useful imaging tool to assess disease activity and response to treatment in GCA patients. It may play a role in predicting GCA phenotype and the patient's prognosis. <h3>REFERENCES:</h3> [1] El Miedany Y et al. Development of GCA PROMs. Semin Arthritis Rheum 2023; 63:152285. [2] El Miedany Y et al. Giant cell arteritis clinical disease activity measures: recommendations for use in clinical practice. Ann Rheum Dis 2023; 82:634. <h3>Acknowledgements:</h3> <b>NIL.</b> <h3>Disclosure of Interests:</h3> <b>None declared.</b>