Serial assessment of ultrasound sensitivity and scores in patients with giant cell arteritis before and 3 and 10 days after treatment.

OBJECTIVES

The objective of this study was to evaluate the sensitivity and scores of vascular US before and after initiating glucocorticoid (GC) treatment in patients with new-onset giant cell arteritis (GCA).

METHODS

Treatment-naïve patients with GCA were prospectively included. 18F-fluorodeoxyglucose (18F-FDG) PET/CT, US and temporal artery (TA) biopsy were performed in all patients. US was repeated 3 and 10 days after GC commencement. Intima-media thickness and presence of halo signs were assessed. Sonographers were unblinded to the clinical data. The OMERACT GCA Ultrasonography score (OGUS) and the halo count (HC) were calculated.

RESULTS

Forty-eight patients were included. Before GC exposure, US sensitivity was 94% (95% CI: 83-99), 73% (95% CI: 58-85), and 71% (95% CI: 56-83) when assessing all vessels, TAs, and large vessels (LVs), respectively. At day 3 and 10, the overall US sensitivity was 92% (95% CI: 78-98, P = 0.16) and 83% (95% CI: 69-92, P = 0.10), respectively. At day 10, the TA-US and LV-US sensitivity was 53% (95% CI: 38-68, P < 0.01) and 60% (95% CI: 44-74, P = 0.13), respectively. The median OGUS decreased from 1.06 (IQR 0.83-1.24) to 0.95 (IQR 0.78-1.14, P < 0.01) and 0.90 (IQR 0.73-1.01, P < 0.001) after 3 and 10 days, respectively. The median HC decreased from 3 (IQR 2-5) to 2 (IQR 1-4, P < 0.01) after 10 days.

CONCLUSION

The vasculitic US findings expressed by OGUS diminished after 3 days of GC treatment. TA-US sensitivity decreased after 10 days, whereas LV-US was less likely to change, highlighting the importance of LV-assessment. Consistent with the EULAR recommendations, these findings encourage prompt US assessment, preferably within 3 days, to ensure an accurate diagnosis.