Imaging-guided stratification in giant cell arteritis: prognostic and therapeutic implications

Imaging has become a cornerstone in the clinical management of giant cell arteritis (GCA), with its role extending beyond diagnosis to include disease monitoring, risk stratification of relapse, and therapeutic decision-making. While imaging modalities have been well-established for diagnostic purposes, growing evidence supports their utility in tracking disease activity and stratifying the risk of relapse. In this narrative review, we discuss the available evidence on the prognostic and therapeutic implications of imaging-guided stratification in GCA, and highlight areas that require further research. Ultrasound assessment of intima-media thickness shows measurable improvement following treatment. While this response is relatively rapid in the cranial arteries, it occurs slowly or very slowly in extracranial vessels. Moreover, ultrasound signs and quantitative indices may be useful for distinguishing remission from relapse. Similarly, arterial inflammation assessed by ¹⁸F-fluorodeoxyglucose positron emission tomography (¹⁸F-FDG PET) also improves with treatment. However, persistent large vessel vascular uptake is often observed in patients deemed to be in clinical remission. The clinical relevance of such subclinical imaging abnormalities remains unclear, underscoring the need for further research before imaging can be routinely employed for disease monitoring. Imaging may also provide valuable prognostic information. Evidence remains conflicting as to whether patients with large-vessel involvement detected by imaging may relapse more frequently, require glucocorticoid-sparing agents more often, and have an increased risk of cardiovascular events compared to those with isolated cranial GCA. However, quantifying vascular inflammation by ultrasound at diagnosis could support risk stratification and inform individualized treatment decisions. Moreover, elevated arterial uptake on ¹⁸F-FDG PET at baseline has been associated with a higher likelihood of late vascular complications, such as aneurysm formation.