We also discuss the sensitivity of FDG-PET imaging in differentiating polymyalgia rheumatica from other diseases that have similar clinical presentation.
The incidence of significant <sup>18</sup>F-FDG uptake in the definitive PMR group was 6% for wrists and for elbows, 88% for glenohumeral and sternoclavicular joints, 25% for acromioclavicular joints, 81% for spinous processes, 69% for ischial tuberosities, and 81% for greater trochanters.
It is possible to observe a decrease or even a disappearance of <sup>18</sup>F-FDG uptake after effective therapy, an event which may be useful for the monitoring of treatment as well as for detection of PMR relapse.
The 4 separate studies in the current protocol focus on: the association of clinical picture of PMR/GCA with PET findings; the validity of 18F-FDG PET/CT scan for diagnosis of PMR/GCA compared with temporal artery biopsy; the prevalence of newly diagnosed malignancies in patients with PMR/GCA, or PMR-like syndrome, with the focus on diagnostic accuracy of 18F-FDG PET/CT scan compared with conventional workup (ie, chest X-ray/abdominal ultrasound); and the impact of disease process, and also steroid treatment on bone mineral density, body composition, and vasculitis/vascular stiffness in PMR/GCA patients.
Increased praepubic <sup>18</sup>F-FDG uptake in patients with PMR is relatively common and this region should be systematically evaluated during differential diagnosis of rheumatic and malignant disease.