Repeated Cranial and Large-Vessel Positron Emission Tomography/Computed Tomography Scans and the Association With Structural Aortic Disease in Giant Cell Arteritis: A Five-Year Observational Study.

Abstract

Objective: Giant cell arteritis (GCA) is characterized by cranial ischemia at diagnosis and late aortic structural disease. Repeated combined cranial and large-vessel fluoro-2-deoxyglucose (FDG) positron emission tomography (PET)/computed tomography (CT) scans were performed to assess the distribution of vasculitis activity over time and the relationship with clinical outcomes.

Methods: Patients were eligible if they were enrolled in a 64-patient inception suspected GCA cohort in 2016 to 2017 and had a positive temporal artery biopsy and/or PET/CT scan at diagnosis. At five years, patients underwent a PET/CT scan, magnetic resonance aortogram, and clinical assessment. Scans were reported for overall metabolic disease activity and a visual FDG avidity grade at each vascular territory.

Results: Sixteen patients met inclusion criteria, and 11 attended the five-year visit. Median age was 75 years, 73% were women, and all were in remission. At five years, 4 (36%) patients had aortic dilatation (range 40-43 mm), and five (45%) had globally active scans. Cranial artery activity resolved in all patients between diagnosis and five years, but aortitis developed in four patients who previously had PET-inactive aortas. Disease-modifying rheumatic drug (DMARD) use at five years was associated with scan inactivity (P = 0.02). There was a trend toward a higher mean aortic diameter in those with aortitis at five years (40.2 mm vs 36.0 mm, P = 0.06) but not those with aortitis at diagnosis.

Conclusion: Vasculitis activity changed from cranial and large vessel to exclusively large vessel by five years. This may explain the preponderance of early cranial and late aortic complications in GCA. The potential role of long-term DMARDs to mitigate smoldering vasculitis warrants further study.