Background/Purpose:

Giant cell arteritis is the most common large vessel vasculitis. ¹⁸F-FDG-PET/CT is known to be a useful imaging technique for diagnosing giant cell arteritis. Scarce data exists on ¹⁸F-FDG-PET/CT in patients with giant cell arteritis in clinical remission. It was shown that ¹⁸F-FDG uptake can persist in patients under immunosuppressive treatment. The decision to withdraw immunosuppressive treatment is normally guided by clinical symptoms and laboratory testing. Under treatment with tocilizumab laboratory testing is not helpful. Therefore ¹⁸F-FDG-PET/CT might be an additional investigation method to device between subclinical persisting inflammation and true remission.

Methods:

31 patients with giant cell arteritis in clinical remission were clinically documented and subjected to ¹⁸F-FDG-PET/CT scanning with a Siemens Biograph™ TruePoint™ PET/CT. Images were evaluated by specialists at the Departments of Nuclear Medicine and Radiology of the University Clinic of Erlangen via a visual grading system. ¹⁸F-FDG-PET/CT scans were graded as active, questionable active and inactive. The scans were graded active when a vascular uptake of the tracer was higher than liver uptake. Additionally, we documented the vascular uptake of the tracer applying the PETVAS score by Grayson et. (0-27).

Results:

Of the 31 patients in clinical remission, two patients presented with a visual active vascular uptake of the tracer in the ¹⁸F-FDG-PET/CT scan. 11 patients had a questionable active tracer uptake and 18 patients had no visual vascular uptake of the tracer. The mean PEVAS score of patients with visual active vascular uptake was 16, with patients with questionable uptake was 9.27 and with no vascular uptake was 7,44. Interestingly the patients with active disease had no systemic inflammation markers. One patient was treated with MTX 15 mg/week and 5 mg Prednisolon/day, the other was without treatment. 6 patients of the cohort were treated with Tocilizumab, all of them had visually no tracer uptake and their mean PETVAS score was 8,33. On the other hand patients with Methotrexate were found in all three groups equally distributed with a mean PETVAS score of 9.20.

Conclusion:

We showed that 11 patients (35,4%) with clinical remission still had visually questionable active ¹⁸F-FDG uptake and 2 patients (6.4%) had visually active ¹⁸F-FDG uptake in an ¹⁸F-FDG-PET/CT scan. It is not clear whether this subclinical ¹⁸F-FDG uptake reflects true activity of the large vessel vasculitis or residual effects due to vascular remodeling. Interestingly all patients under Tocilizumab treatment were in the visual not active group (mean PETVAS=8,33) while patients with MTX were equally distributed among all groups. This result indicates a better immunosuppressive effect of Tocilizumab in comparison to MTX and might be a sign for persisting vasculitis activity in patients with significant ¹⁸F-FDG uptake despite clinical Remission.

« Back to 2018 ACR/ARHP Annual Meeting

ACR Meeting Abstracts - https://acrabstracts.org/abstract/does-an-18f-fdg-pet-ct-in-patients-with-giant-cell-arteritis-in-clinical-remission-make-sense/