18F-FDG positron emission tomography for early diagnosis of giant cell arteritis

Aim

To evaluate the diagnostic performance of positron emission tomography (PET) for early diagnosis of giant cell arteritis (GCA) and to define the criteria for assessment of PET results in patients with established GCA.

Material and methods

We performed standardized 18-fluorodeoxyglucose (18F-FDG) PET scan of the whole body in 44 patients with suspected or established diagnosis of GCA and 25 control patients. The results were evaluated visually and semi-quantitatively with the calculation of the uptake score.

Results

Abnormal 18F-FDG uptake in the aorta and/or large vessels was found in 42 of 44 (95%) patients, in whom the diagnosis of GCA was established or confirmed according to PET results (including 23 patients with fever of unknown origin). In 2 of 44 (5%) patients, there was no pathological uptake in the large vessels, though the diagnosis of GCA was established based on the clinical data and ultrasound. PET has significantly shortened the time to GCA diagnosis. The majority of patients (61-84%) had involvement of aorta, subclavian, axillary and common carotid arteries and more rarely (7%) of pulmonary arteries. Uptake score did not depend on the location of inflammation and the duration of disease.

Conclusion

18F-FDG PET is a highly reliable method for the early diagnosis of GCA, as well as for the assessment of the spread and intensity of inflammation in artery walls. This diagnostic modality should be considered in the management of patients with fever of unknown origin.

Key words

Positron emission tomography, giant cell arteritis, polymyalgia rheumatica, fever of unknown origin.