European Journal of Nuclear Medicine and Molecular Imaging | 2021
Combination of whole body [18F]FDG PET angiography and PET/CT for giant cell arteritis
Abstract
A 75-year-old man presented with fever of unknown origin and acute neck pain and headache. The laboratory test revealed high level of erythrocyte sedimentation rate (ESR: 100 mm/h). Computed tomography (CT) images showed wall thickening and fat stranding around the three major branches of the aortic arch. He was suspected with large vessel vasculitis, and whole body 2-deoxy-2-[18F]fluorod-glucose ([18F]FDG) positron emission tomography angiography (PETA)/CT and standard PET/CT were scheduled for evaluating morphological changes and activities of vasculitis. PETA/CT was performed using continuous bed motion and the acquisition time was from 20 to 44 s after bolus injection. Standard PET/CT scan was obtained 90 min post injection. Stenotic lesions were observed at the three arteries (right common carotid artery, brachiocephalic artery, and left common carotid artery) on PETA/CT (arrowheads) (Fig. A, B: 3D PETA, C: oblique coronal PETA/CT). Standard PET/CT images showed diffuse increased uptake by the three arteries (Fig. D: oblique coronal PET/CT, E: maximum intensity projection). Fusion images of PETA and standard PET illustrated both the stenotic lesions and activities of the affected arteries (Fig. F, red: PETA, green: standard PET). Based on the clinical and the radiological findings, he was finally diagnosed with giant cell arteritis (GCA) according to the classification criteria by the American College of Rheumatology in 1990 [1]. [18F]FDG PET/CT is widely used clinically for diagnosing GCA [2]. [18F]FDG PET/CT can provide information on activated inflammatory cells in inflamed arterial walls but has a limitation in morphological evaluation. CT images of standard PET/CT can easily reveal aneurysmal changes of the vessels, but hardly visualize the vessel lumen. On the other hand, multiphase CT and magnetic resonance imaging (MRI) can evaluate morphological changes and activities of vasculitis [3], though CT has a problem of radiation dose and MRI that of scan range. PETA/CT can be performed with no or slight additional radiation exposure for attenuation correction CT. The combination of [18F]FDG PETA/ CT and PET/CT can be a one-stop shop for the assessment of GCA.