Effects of early corticosteroid treatment on magnetic resonance imaging and ultrasonography findings in giant cell arteritis.

OBJECTIVE To compare the impact of initial corticosteroid treatment on high-resolution MRI and colour-coded duplex sonography (CCDS) findings in patients with GCA (temporal). METHODS Sensitivity and specificity of CCDS and high-resolution contrast-enhanced MRI studies of 59 patients with suspected GCA were retrospectively analysed. Patients were grouped according to the duration of steroid treatment before imaging: 0-1 day, 2-4 days and >4 days. In 41 patients, imaging results were compared with findings of temporal artery biopsy (TAB). RESULTS Sixty-one per cent (36/59) of patients were diagnosed with GCA. TAB findings were positive in 59% (24/41). The compared results of TAB sensitivity of CCDS and MRI under steroid treatment of 0-1 day were 92% and 90%, 2-4 days 80% and 78% and >4 days 50% and 80%, respectively. The compared results of the final clinical diagnosis sensitivity of CCDS and MRI under steroid treatment of 0-1 day was 88% and 85%, 2-4 days 50% and 64% and >4 days 50% and 56%, respectively. CONCLUSION Sensitivity of a first-time CCDS or an MRI for detection of GCA rapidly decreases under corticosteroid treatment. Therefore imaging of patients with suspected GCA should be performed as soon as possible, preferably within the first days of treatment.