Background/Purpose:  Positron emission tomography combined with computed tomography (PET/CT) with ¹⁸F-fluorodeoxyglucose (FDG) can be used to assess large-vessel inflammation in giant-cell arteritis (GCA) and has demonstrated high sensitivity in detecting extra-cephalic forms of the disease, notably in patients without vascular-related symptoms. Few data exist on the merits of repeating this procedure as part of treatment monitoring during follow-up. It remains to be seen whether a repeated procedure during patient follow-up for GCA-related large-vessel involvement demonstrated on FDG-PET/CT is clinically helpful. Our aim was to determine the value of repetitive FDG-PET/CT in giant-cell arteritis (GCA) with large-vessel involvement.

Methods:  We conducted a retrospective multicenter study between 2000 and 2015. Patients were included if 1) GCA was diagnosed according to the American College of Rheumatology criteria. 2) large-vessel involvement was demonstrated on FDG-PET/CT at diagnosis; 3) FDG-PET/CT was repeated at least once during follow-up. We separated the cohort into two groups, according to the indication of the repeated procedure, i.e. for evaluating vascular uptake in patients with disease remission or with disease relapse.

Results:  Thirty-seven patients (24 [65%] women, median age: 68 [55-85]) with large-vessel inflammation on baseline FDG-PET/CT were included. During a median clinical follow-up of 50 [12-162] months, 63 new FDG-PET/CT were performed, including 34 scans in 25 patients with controlled disease and 29 scans in 22 relapsing patients. In patients with controlled disease, repeated FDG-PET/CT showed fewer involved vascular territories than on the previous one in only 15/34 (44%) scans (median involved territories: 2 [0-4] vs. 4 [1-6], respectively; p<0.001), including five (15%) with total disappearance of vascular uptakes, 12 [6-63] months after diagnosis. At the end of the study, 20 patients (80%) still had vascular uptakes on repetitive scans, which did not alter the therapeutic decision unless clinical symptoms and/or an elevated acute phase had resumed. Of the patients with disease relapse, the PET/CT showed increased number of vascular uptakes in 5 cases (17%), whereas the others showed reduced or unchanged vascular uptakes.

Conclusion:  In patients with GCA-related large-vessel involvement, repetitive FDG-PET/CT during follow-up did not provide any reliable additional information, beside clinical and laboratory assessment. Therapeutic management was actually not influenced by the PET/CT results. A prospective study is required to confirm these findings.

« Back to 2016 ACR/ARHP Annual Meeting

ACR Meeting Abstracts - https://acrabstracts.org/abstract/is-there-a-place-for-repetitive-18f-fluorodeoxyglucose-positron-emission-tomography-in-giant-cell-arteritis-with-large-vessel-involvement/