Diagnostic Role and Feasibility of F-FDG PET for Assessing Takayasu Arteritis: Diagnostic Efficacy of Quantifying F-FDG Uptake.

Takayasu arteritis (TAK) is classified as large-vessel vasculitis caused by inflammation. It is often difficult to identify on clinical examination, and F-fluorodeoxyglucose positron emission tomography (F-FDG PET) plays an indispensable role in diagnosing TAK by detecting the location and grade of the inflammatory lesions. The clinical utility of F-FDG PET has been established by clinical evidence, and F-FDG PET was added to the Japanese national health insurance listing in April 2018. In TAK, F-FDG uptake shows typical findings and is easily distinguished, except from physiological uptake. Particularly, the clinical significance of F-FDG PET is that can present not only with stenosis but also without stenosis in the arteries, which means that therapeutic intervention is possible before irreversible stenosis develops in the arteries. Additionally, F-FDG PET has superior diagnostic accuracy because it allows quantitative analysis using the maximum standardized uptake value. The analysis is used for the assessment of disease activity of TAK and can be utilized for therapeutic intervention in case of repeating remission during the follow-up term.