Objective There is currently no diagnostic test for PMR. A characteristic pattern of extracapsular inflammation as assessed by contrast-enhanced MRI (ceMRI) has recently been described in the pelvis of patients with PMR. We aimed to evaluate the performance of inflammatory ceMRI signals at predefined pelvic sites as a diagnostic test for PMR. Methods Pelvic MRI scans of patients with pelvic girdle pain (n = 120), including 40 patients with an expert diagnosis of PMR and 80 controls with other reasons for pelvic pain were scored by three blinded radiologists, who evaluated the degree of contrast enhancement at 19 predefined tendinous and capsular pelvic structures. Different patterns of involvement were analysed statistically. Results The frequency of bilateral peritendinitis and pericapsulitis including less common sites, such as the proximal origins of the m. rectus femoris and m. adductor longus, differed significantly between PMR cases and controls: 13.4 ± 2.7 vs 4.0 ± 2.3. A cut-off of ≥10 inflamed sites discriminated well between groups (sensitivity 95.8%, specificity 97.1%). Bilateral inflammation of the insertion of the proximal m. rectus femoris or adductor longus tendons together with ≥3 other bilaterally inflamed sites performed even better (sensitivity 100%, specificity 97.5%). Conclusion This study confirms that a distinctive MRI pattern of pelvic inflammation (bilateral peritendinitis and pericapsulitis and the proximal origins of the m. rectus femoris and m. adductor longus) is characteristic for PMR. The high sensitivity and specificity of the set of anatomical sites evaluated suggests their clinical usefulness as a confirmatory diagnostic test.

Background Extracapsular inflammation at entheseal sites in the pelvic girdle as demonstrated by magnetic resonance imaging (MRI) was shown to be useful as an additional tool for diagnosing polymyalgia rheumatica (PMR). However, it is unclear whether MRI needs to be performed with contrast enhancement or whether oedema-sensitive sequences are sufficient. Objective To evaluate the performance of T2w TIRM (turbo inversion recovery magnitude) imaging compared to fat-saturated contrast-enhanced (ce) T1w at predefined pelvic sites to detect extracapsular inflammation in patients with PMR. Methods A total of 120 pelvic MRIs of patients with pelvic girdle pain, 40 with clinically diagnosed PMR and 80 controls, were retrospectively scored by three blinded radiologists separately evaluating the MRI with and without contrast enhancement at 19 previously defined pelvic structures. The intra- and interrater reliability and the diagnostic performance of both techniques were statistically analysed and evaluated. Results The detection of inflammatory MRI signals correlated moderately between both techniques (Cohen’s κ 0.583). With ceT1w imaging 20.7% more sites were detected as inflamed compared to T2w TIRM in PMR patients. Inter- and intrareader reliability was superior with ceT1w imaging. If the inflammatory signal was detected at three sites bilaterally including the origin of the rectus femoris muscle or adductor longus muscle, the sensitivity and specificity was 100% and 97.1% by ceT1w imaging vs. 80.8% and 93.3% by T2w TIRM, respectively. Conclusion Contrast enhancement is superior to oedema-sensitive MRI in the detection of extracapsular inflammation in PMR. However, using T2w TIRM also detects many but not all PMR cases.

BackgroundThe diagnosis of polymyalgia rheumatica (PMR) is based on a thorough clinical evaluation of the patient - including exclusion of other diseases, since there is no decisive diagnostic test. A characteristic pattern of extracapsular inflammation in the pelvis of patients with PMR as assessed by contrast enhanced magnetic resonance imaging (MRI) has been recently described (1)ObjectivesTo evaluate the performance of a predefined set of anatomic sites in the pelvis of patients with PMR vs. controls.MethodsA total of 120 pelvic MRI scans of patients who had presented to our tertiary center with pelvic girdle pain in the last 3 years, including 40 patients with an expert rheumatologist diagnosis of PMR and 80 controls with other reasons of pelvic pain was evaluated by 3 radiologists blinded to clinical diagnosis and patient demographics. The experts scored the presence or absence of contrast enhancement at 19 predefined tendinous and capsular pelvic structures. Different patterns of involvement were compared and statistically evaluated by ROC analysis. Kappa statistics were applied to calculate inter- and intrareader agreement.ResultsMostly bilateral peritendinitis and capsulitis including uncommon sites such as the proximal origins of the muscles rectus femoris and adductor longus were found almost exclusively and, thus, typically in PMR patients: the difference in the mean number of sites showing contrast enhancement was significantly different with 13.4±2.7 for PMR vs 4.0±2.3 for controls. A cut-off of ≥10 inflamed sites discriminated very well between the groups resulting in a sensitivity and specificity of 95.8% and 97.1%, respectively. Just concentrating on the most frequently involved anatomic sites bilateral inflammation of proximal M. rectus femoris or adductor longus tendons together with at least 3 other bilaterally inflamed sites performed even better with a sensitivity and specificity of 100% and 97.5%, respectively.ConclusionThis study strongly confirms that the previously described pattern of extracapsular pelvic inflammation as assessed by contrast enhanced MRI is very typical for patients with PMR. In addition, the high sensitivity and specificity of the set of anatomic sites evaluated suggest their definite potential for use as a confirmatory diagnostic test. Reference[1] Fruth M, Buehring B, Baraliakos X, Braun J. Use of contrast-enhanced magnetic resonance imaging of the pelvis to describe changes at different anatomic sites which are potentially specific for polymyalgia rheumatica. Clin Exp Rheumatol. 2018; 36 Suppl 114(5):86-95.Disclosure of InterestsMartin Fruth: None declared, J Kozik: None declared, P Martin-Seidel: None declared, Annika Seggewiss: None declared, Xenofon Baraliakos Grant/research support from: AbbVie, Boehringer Ingelheim, Bristol-Myers Squibb, Celgene, Centocor, Chugai, Janssen, MSD, Novartis, Pfizer Inc, Roche and UCB, Grant/research support from: AbbVie, Pfizer, Merck Sharp & Dohme, UCB Pharma, Novartis, Consultant for: AbbVie, Bristol-Myers Squibb, Boehringer Ingel...