Positron emission tomography in giant cell arteritis: a new diagnostic tool?

Authors’ response to the eLetter by Moiseev et al

“…Involvement of the supra-aortic branches, as also confirmed by Moiseev et al ,2 seems to be relevant. Increased uptake restricted to the aorta may have more limited specificity since it may occur in the setting of severe atherosclerosis, periaortitis, isolated idiopathic aortitis or IgG4-related disease 6 7…”

“…We thank Moiseev and colleagues for their interest in our manuscript addressing the sensitivity and specificity of positron emission tomography (PET)/CT with 18 fluorodeoxyglucose (FDG) for detecting large-vessel inflammation in patients with giant-cell arteritis (GCA)1 and for sharing their own data 2. We totally agree with the authors that PET-CT may be a useful diagnostic tool for GCA although it may be still premature to state that PET/CT should be an independent diagnostic procedure.…”

“…The identification of a referral standard is in itself difficult. As Moiseev and colleagues point out,2 PET/CT may detect large-vessel involvement in patients with a negative temporal artery biopsy and, therefore, a positive biopsy may not be the only comparator when assessing the diagnostic performance of PET/CT. Regarding existing classification criteria, many investigators are currently dissatisfied with the 1990 American College of Rheumatology (ACR) classification criteria3 which, in fact, are not diagnostic criteria and do not perform appropriately as such 4.…”

The role of temporal artery biopsy in patients with giant-cell arteritis is debated

“…In our centre, we prefer to use PET as a second-line imaging modality in ultrasound-negative patients with suspected GCA 7. This method allows both to identify vasculitis of the large arteries and to rule out infections or tumours that can be associated with constitutional symptoms and laboratory findings typical for GCA.…”

Biological agents for giant cell arteritis: treat to target

“…The isolated increase in inflammatory biomarkers is usually not sufficient to diagnose a relapse4 while clinical scores, such as the Birmingham Vasculitis Activity Score (BVAS), have only limited utility in GCA 5 . 18 Fluorodeoxyglucose positron-emission tomography is a promising method though its value for evaluation of GCA activity is not established 6. In the Conway et al study, persistent constitutional symptoms and elevated acute-phase reactants initially felt to be possibly related to active GCA were ultimately attributed to an alternative cause in two of five patients.…”