Ultrasound cut-off values for intima-media thickness of temporal, facial and axillary arteries in giant cell arteritis.

Objective: To evaluate the intima-media thickness (IMT) of arteries involved in GCA for determining cut-off values.

Methods: Forty newly diagnosed GCA patients in a fast-track GCA clinic and 40 age- and sex-matched controls were included. IMT measurement was performed at or within 24 h after diagnosis. The common superficial temporal arteries with their frontal and parietal branches and the facial arteries were bilaterally examined with a 10-22 MHz probe and the axillary artery with a 6-18 MHz probe. Receiver operating characteristics analysis was performed for estimating cut-off values.

Results: The mean age was 72 years (s.d. 9) and 68% were females. In the control group, IMT was 0.23 mm (s.d. 0.04), 0.19 mm (s.d. 0.03), 0.20 mm (s.d. 0.03), 0.24 mm (s.d. 0.05) and 0.59 mm (s.d. 0.10) for the common superficial temporal arteries, the frontal and parietal branches, the facial arteries and the axillary arteries, respectively. In vasculitic segments of GCA patients, IMT was 0.65 mm (s.d. 0.18), 0.54 mm (s.d. 0.18), 0.50 mm (s.d. 0.17), 0.53 mm (s.d. 0.16) and 1.7 mm (s.d. 0.41), respectively. Cut-off values are 0.42, 0.34, 0.29, 0.37 and 1.0 mm, respectively, with 100% sensitivities and specificities for common superficial temporal arteries, for frontal branches and for axillary arteries and sensitivities of 97.2 and 87.5% and specificities of 98.7 and 98.8% for parietal branches and facial arteries, respectively. The intraclass correlation coefficient was between 0.87 and 0.98.

Conclusion: IMT measurement can correctly distinguish vasculitic from normal arteries in suspected GCA.