Positron Emission Tomography/Computerized Tomography in Newly Diagnosed Patients with Giant Cell Arteritis Who Are Taking Glucocorticoids

• Published in: Journal of rheumatology 2017-12, Vol.44 (12), p.1859-1866
• Main Authors: Clifford, Alison H, Murphy, Elana M, Burrell, Steven C, Bligh, Mathew P, MacDougall, Ryan F, Heathcote, J Godfrey, Castonguay, Mathieu C, Lee, Min S, Matheson, Kara, Hanly, John G
• Format: Article
• Language: English
• Subjects: Aged; Aged, 80 and over; Brain - diagnostic imaging; Female; Giant Cell Arteritis - diagnostic imaging; Giant Cell Arteritis - drug therapy; Glucocorticoids - therapeutic use; Humans; Male; Middle Aged; Positron Emission Tomography Computed Tomography; Prednisone - therapeutic use; Temporal Arteries - diagnostic imaging; Treatment Outcome
• ISSN: 0315-162X; 1499-2752
• DOI: 10.3899/jrheum.170138

Large vessel uptake on positron emission tomography/computerized tomography (PET/CT) supports the diagnosis of giant cell arteritis (GCA). Its value, however, in patients without arteritis on temporal artery biopsy and in those receiving glucocorticoids remains unknown. We compared PET/CT results in GCA patients with positive (TAB+) and negative temporal artery biopsies (TAB-), and controls. Patients with new clinically diagnosed GCA starting treatment with glucocorticoids underwent temporal artery biopsy and PET/CT. Using a visual semiquantitative approach, 18F-fluorodeoxyglucose (FDG) uptake was scored in 8 vascular territories and summed overall to give a total score in patients and matched controls. Twenty-eight patients with GCA and 28 controls were enrolled. Eighteen patients with GCA were TAB+. Mean PET/CT scores after an average of 11.9 days of prednisone were higher in patients with GCA compared to controls, for both total uptake (10.34 ± 2.72 vs 7.73 ± 2.56; p = 0.001), and in 6 of 8 specific vascular territories. PET/CT scores were similar between TAB+ and TAB- patients with GCA. The optimal cutoff for distinguishing GCA cases from controls was a total PET/CT score of ≥ 9, with an area under the receiver-operating characteristic curve of 0.75, sensitivity 71.4%, and specificity 64.3%. Among patients with GCA, these measures correlated with greater total PET/CT scores: systemic symptoms (p = 0.015), lower hemoglobin (p = 0.009), and higher platelet count (p = 0.008). Vascular FDG uptake scores were increased in most patients with GCA despite exposure to prednisone; however, the sensitivity and specificity of PET/CT in this setting were lower than those previously reported.