Impact of the Spatial Resolution of Several Contrast-enhanced 3D T1-WI Sequences When Diagnosing Giant Cell Arteritis (GCA)

Giant cell arteritis (GCA) (or Horton's disease) is a segmental and focal inflammatory arteritis affecting large and medium-sized arteries. Its incidence is estimated at 17.8/100,000 in subjects over 50 years old (and 46/100,000 in subjects over 70 years old). This disease remains a severe pathology due in particular to its vascular, ophthalmological, neurological, cardiac and aortic complications. In case of suspected CAG, management is a real therapeutic emergency. Indeed, only corticosteroid therapy started as early as possible can prevent the occurrence of these complications. The gold standard for the diagnosis of CAG has long been the temporal artery biopsy, but imaging is now considered as a 1st line diagnostic examination for the diagnosis of CAG according to the EULAR 2018 recommendations. Notably, temporal artery MRI has excellent sensitivity and specificity for diagnosis. However, the high diagnostic performance of MRI has been achieved by performing 3D T1 black blood and fat saturation sequences in high resolution (\<0.7mm), which are not accessible in all centers in France and worldwide. The realization of identical sequences with a lower resolution could allow a greater generalization of these sequences and improve the diagnostic management of GCA patients, including in non-expert centers. The objective of our study is to investigate the diagnostic performance of several 3D T1 black blood and fat saturation sequences for the diagnosis of GCA.