Imaging of polymyalgia rheumatica: indications on its pathogenesis, diagnosis and prognosis

Objectives. Imaging is one of the most appealing techniques to explore PMR, a disease whose causes, development mechanisms and anatomical targets of inflammatory damage are still scarcely known. This review is concerned with an appraisal of PMR with different imaging modalities with a view to highlighting possible clues to its pathogenesis, diagnosis and prognosis. Methods. A systematic literature research was performed searching PubMed until July 2010. The Cochrane Library was searched for the relevant reviews, and the abstracts of the ACR and European League Against Rheumatism congresses of the period 2005-10 were reviewed. Results. A total of 1059 papers were retrieved, 46 of which were selected at the end of the review process; 6 of them were concerned with two different imaging techniques. Of these papers, 6 (11.5%) were concerned with conventional radiology; 8 (15.4%) with scintigraphy; 17 (32.7%) with ultrasonography (US); 15 (28.8%) with MRI; and 6 (11.5%) with PET. MRI, US and PET appeared to be the most promising imaging techniques. Bilateral subacromial bursitis, biceps long head tenosynovitis and trochanteric bursitis were particularly consistent findings. In addition, MRI and PET showed interspinous bursitis and PET frequently showed large-vessel vasculitis. Few papers have addressed the role of imaging for diagnosis, differential diagnosis and prognosis of PMR. Conclusions. Imaging plays an important role in the comprehensive evaluation of PMR, including its pathogenesis, diagnosis and prognosis. Most of its potential is still unexplored, which fact should stimulate further research.