Musculoskeletal magnetic resonance imaging findings support a common spectrum of giant cell arteritis and polymyalgia rheumatica.

ABSTRACT

OBJECTIVES: To investigate the proportion and distribution of contrast enhancement (CE) of musculoskeletal structures with MRI of the thorax/abdomen/pelvis in giant cell arteritis (GCA). METHODS: CE at 34 musculoskeletal sites was rated with a 4-point ordinal scale. Patients were divided into groups with/without glucocorticoid (GC) treatment and with/without symptoms of polymyalgia rheumatica (PMR). Two composite scores were created an MRI-score, including seven sites and a Limited-MRI-score, including four sites. RESULTS: Retrospectively, 90 consecutive patients with GCA were included. The population included 54 and 36 patients with and without PMR symptoms, respectively, and 45 (50%) patients were receiving GCs at the time of MRI. CE was found in 90.7% of lumbar spines, 87.5% of the pelvis, 82.2% of shoulder girdles and in 95.6% at any site in patients without GCs. The proportion of patients without and with GCs with at least moderate enhancement was 91.1%/75.6% at ≥ 1-3, 75.6%/51.1% at ≥ 4-6 and 64.4%/28.9% at ≥ 7-9 sites. The mean difference between the proportion of pathological CE in patients with and without GCs was 27.4% for synovial sites and 18.3% for periarticular/musculotendinous sites. Both composite scores captured substantial differences between groups, correlation was very strong between scores. CONCLUSIONS: MRI shows CE of musculoskeletal structures typical of PMR in most patients with GCA, supporting the concept of "GCA-PMR Spectrum Disease". Changes are more frequent at periarticular/musculotendinous sites and in the presence of PMR symptoms. A clear response to GCs is evident, less so for periarticular/musculotendinous sites.