Atherosclerosis as a potential pitfall in the diagnosis of giant cell arteritis.

Objective: To explore whether the increase in the intima-media thickness (IMT) in arteriosclerotic disease correlates with the increase in the IMT in temporal arteries (TAs) and if that could mimic the US GCA halo sign.

Methods: Consecutive patients ⩾50 years old with high vascular risk and without signs or symptoms of GCA were included. The carotid US IMT measurements were obtained using a standardized software radiofrequency-tracking technology. Colour Doppler US and grey-scale measurements of the IMT in the branches of both TAs were performed by a second sonographer using a 22 MHz probe.

Results: Forty patients were studied (28 men) with a mean age of 70.6 years. The carotid IMT exhibited significant correlation with the TA IMT. A carotid IMT >0.9 mm was associated with a temporal IMT >0.3 mm. Only one patient had an IMT >0.34 mm in two branches.

Conclusions: Atherosclerotic disease with a carotid IMT >0.9 mm increases the TA IMT and might mimic the halo sign. As atherosclerosis is common in this age group, we propose a cut-off of TA IMT >0.34 mm in at least two branches to minimize false positives in a GCA diagnosis.