Fluorine-18 Fluoro-2-Deoxyglucose Positron Emission Tomography Uptake in the Superficial Temporal and Vertebral Arteries in Biopsy Positive Giant Cell Arteritis
A 78-year-old woman presented to our hospital with acute visual loss in her left eye. She reported two weeks of jaw claudication and an exacerbation of long-standing polymyalgia rheumatica. She was taking 5 mg prednisone daily. Ophthalmic examination revealed a swollen and pale optic disc consistent with arteritic anterior ischemic optic neuropathy. Temporal arteries were normal on clinical examination. C-reactive protein was 14 mg/L (reference, <5 mg/L), and erythrocyte sedimentation rate was 23 mm/h (laboratory reference, <15 mm/h). She was treated empirically for giant cell arteritis (GCA) with intravenous methylprednisolone 1 g at 0, 24, and 48 hours. Thirty-six hours after the initial dose, she underwent fluorine-18 fluoro-2-deoxyglucose positron emission tomography (18F-FDG PET) of the head, neck, and thorax using a novel low-dose (100 MBq) protocol on a Siemens BiographTM mCT time-of-flight PET-CT scanner with 1-mm computed tomography (CT) slice reconstruction. The patient was positioned with arms by her side to allow better visualization of the craniocervical vessels.
Increased tracer uptake (compared with background activity) was detected in the vertebral and carotid arteries (Fig. 1), bilateral superficial temporal arteries (Fig. 2), and occipital and subclavian arteries. Left-sided temporal artery biopsy performed 24 hours after the scan showed transmural GCA (Fig. 2).
This case illustrates the potential for newer -generation PET-CT scanners to detect vasculitis in the superficial cranial and cervical arteries. These vessels were poorly visualized on older scanners and excluded from analysis in larger PET studies in GCA.1,2 The diagnostic accuracy of this protocol for biopsy-positive GCA is currently under investigation (clinicaltrials.gov ID: NCT02771483).