AB1077 Utility of 18F-Fluoro-Dexoxyglucose Positron Emission Tomography for the Diagnosis of Polymyalgia Rheumatica
Authors: M. Sondag, X. Guillot, F. Verhoeven, C. Prati, H. Boulahdour, D. Wendling
Journal: Annals of the Rheumatic Diseases (2015)

<h3>Background</h3> Polymyalgia rheumatica (PMR) is a frequent inflammatory rheumatism of elderly people with girdles arthralgia, stiffness and good response to steroids. The ACR/EULAR 2012 criteria provide help for the diagnosis but there is no gold standard and the diagnosis is often difficult when patients have atypical presentations. The place of imaging becomes then important to search elements for diagnosis and dismiss other differential diagnosis like deep-malignancy. With this in mind the 18f-Fluoro-Dexoxyglucose Positron Emission Tomography (TEP-SCAN) seems to be an excellent imaging tool for this purpose. <h3>Methods</h3> We have analysed retrospectively 49 patients with a clinical presentation of PMR and who had a TEP-SCAN. 22 patients had a polymyalgia already treated and were addressed principally for lack of response to steroids. 10 sites where analysed by a rheumatologist: shoulders, acromio-clavicular and sterno-clavicular joints, interspinous space, greater trochanter, hips, ischial tuberosities, iliac antero superior and inferior entheses, symphysis pubis. We quote 0 for absence of fixation and 1 for a fixation at least unilateral. We did not use the scoring system modified by Goerres et al. and the SUVmax. <h3>Results</h3> The characteristics of the population were mean age 67.2 years, 45% women, CRP 28.7mg/L, ESR 35.9mm; 9.0 mg/day of prednisone and an ACR/EULAR score without echography 4.63/6. 29 diagnosis of isolated PMR has been confirmed, 4 PMR with Horton disease, 6 PMR syndrome associated with other diseases or "PMR-like" (1 paraganglioma, 2 inflammatory myositis, 2 hemopathy, 1 lung neoplasia recently treated), and for 10 patients the diagnosis of PMR has been refuted. For the group of 39 patients with PMR disease, the 5 sites with most FDG uptake were the great trochanter (30/39, 77%), shoulders (26/39, 66%), ischial tuberosities (21/39, 54%), sterno-clavicular joint (17/39, 44%), interspinous space (15/39, 38%) but not statistically significantly different compared to the group of 10 patients with other final diagnosis (4/10, 40%; 6/10, 60%; 3/10, 30%; 1/10, 10%; 1/10, 10%). We have noted more FDG uptake on shoulders and hips in the group without steroids compared to the group with steroid with a significant difference (87% vs 46%, p&lt;0,01 and 43% vs 8%, p&lt;0,01). The total number of sites with FDG uptake for each patient was significantly different in the confirmed PMR group compared to the non confirmed PMR group: 3,897 sites vs 2,1 sites (p&lt;0,034) and significantly different in the group without steroids compared to the group with steroids (17mg/day): 4.56 vs 2.61 (p&lt;0,0033). <h3>Conclusions</h3> The diagnosis of PMR is difficult and TEP SCAN is an interesting tool in particular for differential diagnosis like vasculitis, infection or neoplasm. Our study shows that it is essential to stop or maximally decrease steroids before the TEP-SCAN because masking inflammatory activity in articular or peri-articular sites. Perhaps more than the localisation of the FDG uptake, the number of sites with FDG uptake seems to be more significant and should be confirmed by larger studies. <h3>Disclosure of Interest</h3> None declared