diagnosis of Giant cell arteritis

• ↑ ESR (Se 84%, Sp 30%), ↑ CRP (Se 86%, Sp 30%), anemia.

• Temporal artery bx (shows vasculitis & granulomas) whenever GCA suspected (Se ≤85%);

• consider bilat to ↑ yield (3–7% discordant).

• If bx ⊖ or suspect aortitis/large vessel involvement: U/S (halo sign) or MRA of temporal/cranial arteries, or CTA, MRA, or PET of aorta/large arteries (Arthritis Rheumatol 2021;73:1349).

• Some advocate imaging upfront to r/o, but requires imaging expertise (Ann Rheum Dis 2018;77:636 & 2020;79:19).