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Large Vessel GCA — SCE Rheumatology MCQ

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HardMusculoskeletal ImagingLarge Vessel GCASCE Rheumatology

A 72-year-old man has weight loss, polymyalgic symptoms and persistently raised inflammatory markers. Temporal and axillary artery ultrasonography is non-diagnostic. FDG PET-CT demonstrates smooth, circumferential arterial-wall uptake greater than hepatic uptake throughout the thoracic aorta and in both subclavian and axillary arteries. There is minimal arterial calcification. What is the most likely interpretation?

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Correct answer: E — Active large-vessel vasculitis with aortic involvement (large-vessel GCA)

The correct answer is **B: active large-vessel GCA**. In an older patient with systemic inflammation and polymyalgic symptoms, smooth circumferential FDG uptake greater than liver activity across the aorta and bilateral subclavian–axillary territories is characteristic of extracranial large-vessel inflammation. EULAR recognises FDG-PET as an appropriate modality for assessing extracranial arteries in suspected GCA. Atherosclerotic uptake is generally less intense and is more often heterogeneous or associated with calcified plaque, although imaging discrimination is not perfect. Normal vascular uptake should not be intense relative to the liver. Aortic dissection is diagnosed from structural findings such as an intimal flap rather than this metabolic pattern. Lymphoma usually produces nodal or mass-like uptake rather than symmetric circumferential uptake confined to multiple arterial walls.

Reference: Dejaco C, et al. EULAR recommendations for the use of imaging in large vessel vasculitis in clinical practice: 2023 update. Ann Rheum Dis. 2024;83:741–751. https://pubmed.ncbi.nlm.nih.gov/37550004/