Figure 2.

Clinical value of FDG-PET findings. A, Global summary score of arterial FDG (PETVAS) calculated in patients with large vessel vasculitis (LVV) during clinical remission predicts future clinical relapse. Patients with high PETVAS (≥ 20) were significantly more likely to relapse than patients with lower PETVAS (< 20) [6/11 (45%) vs 3/28 (15%); p=0.03]. B, PET-CT obtained in a patient with giant cell arteritis during clinical remission (disease duration=3 years, taking prednisone 2.5mg every other day) shows severe FDG uptake throughout the aorta and branch vessels (left panel, white arrows). Patient experienced disease relapse (mesenteric ischemia, fatigue, newly elevated acute phase reactants) one month after the baseline scan and was treated with methotrexate and tapered glucocorticoids with improvement of arterial FDG uptake (right panel, white arrows). C, Patient with GCA in apparent clinical remission (disease duration = 1 year, taking prednisone 7mg per day) had severe FDG arterial uptake in the aorta and branch vessels with normal inflammatory markers. Upon further reduction of daily prednisone to 3mg per day over the subsequent 6 months, the patient experienced clinical relapse (polymyalgia rheumatica, fatigue, elevated acute phase reactants) requiring additional therapy. D, A temporal artery biopsy performed in a patient with GCA during clinical remission with FDG-PET CT suggestive of active vasculitis demonstrated transmural inflammation with giant cells (inset).