18F-FDG PET molecular imaging: A relevant tool to investigate chronic inflammatory rheumatisms in clinical practice?

18F-Labeled Fluorodeoxyglucose-Positron Emission Tomography (18F-FDG PET) is a molecular imaging tool commonly used in practice for the assessment of many cancers. Thanks to its properties, its use has been progressively extended to numerous inflammatory conditions, including chronic inflammatory rheumatism (CIR) such as rheumatoid arthritis (RA), spondylarthritis (SpAs) and polymyalgia rheumatica (PMR). 18F-FDG PET is currently not recommended for the diagnostic of CIRs. However, this whole-body imaging tool has emerged in clinical practice, providing a general overview of systemic involvement occurring in CIRs. Numerous studies have highlighted the capacity of 18F-FDG PET to detect articular and extra articular involvements in RA and PMR. However, the lack of specificity of 18F-FDG limits its use for diagnosis purpose. Finally, the key question is the definition of the best way to integrate this whole-body imaging tool in the patient's management workflow.

Venous thromboembolism during systemic inflammatory and autoimmune diseases associated with myelodysplastic syndromes, chronic myelomonocytic leukaemia and myelodysplastic/myeloproliferative neoplasms: a French multicentre retrospective case-control study.

OBJECTIVES: Myelodysplastic syndromes (MDS) and chronic myelomonocytic leukaemia (CMML) are associated with systemic inflammatory and autoimmune diseases (SIADs) in 10-30% of cases. The aims of this study were (i) to evaluate the prevalence of venous thromboembolism VTE in patients presenting with both MDS/CMML and SIADs, (ii) to describe risk factors associated with thrombosis, and (iii) to analyse the impact of VTE on overall survival and transformation to acute myeloid leukaemia in comparison to patients with MDS/CMML-associated SIADs without VTE. METHODS: This retrospective multicentre case-control study was conducted among patients with MDS/CMML and dysimmune disorders and featured in the French retrospective database of the French Network of Dysimmune Disorders Associated with Hemopathies (MINHEMON), diagnosed with MDS/CMML and dysimmune disorders. RESULTS: During a median follow-up of 16 months (5-48) VTE occurred in 35 patients (21.6 %) whereas 127 patients did not. Among those with VTE, 8 patients (22.9%) experienced two or more VTE. Common prothrombotic risk factors were not significantly different in patients with or without VTE. CMML was more frequent in patients without VTE (37 % vs. 14.3%, p=0.01), whereas myelodysplasic/myeloproliferative neoplasm (MDS/MPN) was higher in VTE patients (20 % vs. 5.5 %, p=0.01). In a multivariate analysis, only MDS/CMML progression at the time of VTE (odds ratio 28.82, 95 % CI (5.52-530.70) was significantly associated with VTE. When treated with an anticoagulation therapy, bleeding occurred in 19.4% of cases (6/31). Overall survival was not significantly different between patients with and without VTE (p=0.68). Leukaemia-free survival between groups was not significantly different (p=0.83). CONCLUSIONS: VTE is a common complication in MDS/CMML-associated SIADSs with an increased risk of bleeding when treated by anticoagulants. In the MDS/CMML subgroup, SIADS flares and MDS/CMML progression seem to be prothrombotic risk factors.

Use of 18F FDG PET-CT to discriminate polymyalgia rheumatica and atypical spondylarthritis in clinical practice.

OBJECTIVE: To evaluate the relevance of 18F-labeled fluorodeoxyglucose-positron emission tomography/computed tomography (18F-FDG PET-CT) for discriminating polymyalgia rheumatica (PMR) and spondylarthritis (SpA) in atypical presentations. METHODS: In 2 rheumatology departments, we identified PMR and atypical SpA patients who underwent 18F-FDG PET-CT and compared the 2 groups. The relevant 18F-FDG PET-CT findings identified on univariate analyses as discriminant for both groups were entered into a multivariable logistic regression model to derive a composite musculoskeletal score. RESULTS: Between September 2012 and August 2018, we enrolled 35 PMR and 27 SpA patients (median [interquartile range] age 71 years [63.5-74.5] and 54 years [41.5-63], P<0.001). 18F-FDG uptake in enthesis/bursae was more frequent in PMR than SpA (ischial tuberosities: 88.6% vs. 48.1%, P<0.001; interspinous processes: 91.4% vs. 51.9%, P<0.001). 18F-FDG uptake in sacroiliac joints was specific to SpA but rare (14.8% vs. 0 in PMR, P<0.05). The intensity of 18F-FDG uptake was similar in both conditions. The musculoskeletal score, including 18F-FDG uptake of the shoulders, ischial tuberosities and interspinous process, was higher for PMR than SpA patients (2.74 vs. 1.11, P<0.001). A score≥2 provided sensitivity and specificity of 74.1% and 77.1% for the diagnosis of PMR. CONCLUSION: 18F-FDG PET-CT patterns of atypical SpA and PMR widely overlap, so differentiating the conditions is challenging. The use of the proposed PET-CT composite score could improve the diagnostic performance of 18F-FDG PET-CT to discriminate these 2 entities in clinical practice.