Background/Purpose: PET-CT scan with 18F-Fluorodeoxyglucose (18F-FDG) has been frequently used as a tool to assess disease activity in Takayasu arteritis (TA) and increased 18F-FDG uptake in arteries is considered a surrogate marker of ongoing arterial inflammation. A previous cross-sectional study showed an association between the maximal standardized uptake value (SUVmax) in TA and disease activity in TA. To date, it is not known whether 18F-FDG uptake in arteries is associated with disease progression in TA with the development of new angiographic lesions. This study aims to evaluate associations between 18F-FDG uptake in arteries from TA and the risk to develop relapses, ischemic events, sustained remission (i.e. absence of disease activity and complete withdrawal of glucocorticoids for at least 6 months), new angiographic lesions and the need to change therapy in TA patients.

Methods: TA patients underwent PET-CT scan with 18F-FDG with arterial uptake measured by the SUV and SUVmax in arterial walls to asses disease activity and were longitudinally assessed for disease activity using Kerr’s criteria and for the development of new angiographic lesions by magnetic resonance angiography and/or by computerized tomography angiography.

Results: Amongst 36 TA patients initially evaluated by 18F-FDG PET-CT scan, 32 were longitudinally followed for a median of 83.5 months. The median SUVmax value in arteries was 1.57 (1.16-2.23). At baseline, 20 TA patients (62.5%) had SUVmax ≥ 1.3, whereas 11 TA patients (34.4%) had active disease by Kerr’s criteria. At follow-up, 23 (71.9%) patients had at least one disease relapse at a median of 17.0 months and new arterial lesions were observed in 14 (43.8%) cases. There were no differences regarding the baseline SUV value in arteries that developed and arteries that did not develop new angiographic lesions in TA patients. A higher frequency of disease relapses (85.0% vs. 50.0%, p = 0.049) and the need for changing immunosuppressive therapy (85.0% vs. 41.7%, p = 0.018) was observed in TA patients with SUVmax ≥1.3 at baseline compared with those with SUVmax <1.3. No differences regarding SUVmax ≥1.3 in arteries and the development of ischemic events, sustained remission and new angiographic lesions were found in TA patients. Using the Kaplan-Meier curve, a trend for a higher frequency of relapses was observed in TA patients with SUVmax ≥1.3 (p = 0.056) by the log rank test. No independent associations were found between baseline SUVmax ≥1.3 and the risk of relapses (HR = 1.07; 95CI: 0.39-2.92; p = 0.892) or between baseline SUVmax ≥1.3 and the risk of developing new angiographic lesions in (HR = 0.24; 95CI: 0.02-2.57; p = 0.239) by the multivariate Cox’s proportional hazard analysis.

Conclusion: There is no association between arterial SUV and development of new arterial lesion in TA, but arterial SUVmax in TA patients is marginally associated with a higher frequency of disease relapses and with the need for changing immunosuppressive therapy.

Arraes AE, de Souza AW, Mariz HA, et al. (18)F-Fluorodeoxyglucose positron emission tomography and serum cytokines and matrix metalloproteinases in the assessment of disease activity in Takayasu’s arteritis. Rev Bras Reumatol 2016;56:299-308.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/pet-ct-findings-and-clinical-outcomes-in-takayasu-arteritis-does-18f-fluorodeoxyglucose-uptake-in-arteries-predict-relapses/