Purpose of review
Giant cell arteritis (GCA) has classically been diagnosed by temporal artery biopsy and treated with high-dose, long-term glucocorticoid therapy. Noninvasive imaging increasingly is employed for diagnostic purposes, but further studies are needed to determine the role of imaging in monitoring longitudinal disease activity. Glucocorticoid-sparing therapy mitigates the numerous adverse effects of glucocorticoids. This review addresses new developments in these areas.
For diagnosis, when performed at a center with expertise in its use, temporal artery ultrasound has an estimated sensitivity and specificity of 78 and 79%, respectively. State-of-the-art time-of-flight positron emission tomography/computed tomography (PET/CT) has an estimated sensitivity and specificity of 71 and 91%, respectively. The sensitivities of both imaging modalities decrease following glucocorticoid administration. Tocilizumab is an effective glucocorticoid-sparing therapy, demonstrating sustained glucocorticoid-free remission in 56% of patients receiving weekly tocilizumab compared with 18% of patients receiving a 52-week prednisone taper. The traditional acute phase reactants are of no value in patients treated with interleukin-6 receptor (IL6-R) blockade, and thus, the development of new biomarkers is an important priority in the field.
Noninvasive imaging techniques are increasingly used in the absence of temporal artery biopsy to confirm diagnostic suspicions of GCA. Tocilizumab reduces the cumulative glucocorticoid exposure and increases the rate of sustained remission. Ongoing efforts are directed towards new methods to identify disease flares.