Background Diagnosis of giant cell arteritis (GCA) is still a challenge. 18F-fluoro-deoxyglucose positron emission tomography scan (FDG-PET) and computed tomography angiography (CTA) are promising imaging techniques for the detection of GCA
Objectives To compare the diagnostic performance of FDG-PET and CTA in patients with giant cell arteritis (GCA).
Methods FDG-PET and CTA were acquired in 24 consecutive patients in whom temporal artery biopsy (TAB) was performed for suspected GCA. Results of FDG-PET and CTA were compared with the final clinical diagnosis based on a) the American College of Rheumatology GCA criteria set, b) clinical judgment including outcome under corticosteroids, and c) the absence of an alternative diagnosis after a 6 months follow-up. Sensitivity, specificity, and positive and negative predictive values (PPV, NPV) were calculated for each method.
Results Fifteen of the 24 patients (62.5%) were ultimately diagnosed as having GCA. Strong FDG uptake in large vessels was found in 10 patients who all had GCA. Mean maximal standard uptake values (SUVmax) per patient measured at all the arterial territories were of 3.7 [range: 2.8–4.7]. FDG uptake was negative in 14 patients including 9 and 5 patients without and with GCA, respectively. Mural thickening suggestive of aortitis or branch vessel arteritis was observed on CTA in 11 patients with and 2 patients without GCA. No mural thickening was observed in 11 patients including 7 patients without and 4 patients with GCA. Overall, sensitivity of FDG-PET and CTA was 66.7% and 73,3%, respectively; specificity was 100% and 84.6%, NPV was 64.3% and 64.6%, and PPV was 100% and 84.6%, respectively.
Conclusions Both FDG-PET and CTA have a strong diagnostic yield for the diagnosis of GCA. FDG-PET appeared to have a higher PPV as compared to CTA and may be the preferred noninvasive technique to evaluate patients with suspected GCA.
Disclosure of Interest None declared