Increased 67gallium uptake among polymyalgia rheumatica patients. Is it additional evidence of its vasculitic nature?

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.

[Vasculitis assessment with [18F]FDG positron emission tomography]

[18F]fluorodeoxyglucose positron emission tomography (PET) is a noninvasive metabolic imaging modality that is well-suited to the assessment of activity and extent of large vessel vasculitis. PET imaging has demonstrated its usefulness in diagnosing giant cell arteritis (notably in its silent form), Takayasu's arteritis, and unclassified aortitis. PET imaging could be more effective than magnetic resonance imaging in detecting the earliest stages of vascular wall inflammation. The visual grading of vascular [18F]FDG uptake makes it possible to discriminate arteritis from active atherosclerosis, providing therefore high specificity. High sensitivity can also be achieved provided scanning is performed during active inflammatory phase, preferably before starting corticosteroid treatment. Prospective studies are needed to determine the exact value of PET imaging in assessing other vasculitis subsets, infectious aortitis, and large vessel vasculitis outcome and response to immunosuppressive treatment.

Polymyalgia rheumatica: diagnosis and treatment

Polymyalgia rheumatica (PMR) typically manifests as inflammatory pain in the shoulder and/or pelvic girdles in a patient over 50 years of age. This condition was long underrecognized and therefore underdiagnosed. Today, however, overdiagnosis may occur. Physicians must be aware that many conditions may simulate PMR, including diseases that carry a grim prognosis or require urgent treatment. PMR may be the first manifestation of giant cell arteritis, and a painstaking search for other signs is mandatory. PMR may inaugurate other rheumatologic diseases such as rheumatoid arthritis, RS3PE syndrome, spondyloarthropathy, systemic lupus erythematosus (SLE), myopathy, vasculitis, and chondrocalcinosis. Finally, PMR may be the first manifestation of an endocrine disorder, a malignancy, or an infection. Failure to respond to glucocorticoid therapy should suggest giant cell arteritis, malignant disease, or infection. Ultrasonography may assist in the diagnosis by showing bilateral subdeltoid bursitis. Glucocorticoids are the mainstay of the treatment of PMR. Although the optimal starting dosage and tapering schedule are not agreed on, a low starting dosage and slow tapering may decrease the relapse rate. Methotrexate is probably useful when glucocorticoid dependency develops. In contrast, TNF-alpha antagonists are probably ineffective.