[Positron emission tomography/computed tomography in rheumatology]. / Positronenemissionstomographie/Computertomographie in der Rheumatologie.

Combined positron emission tomography/computed tomography (PET/CT) is a whole-body imaging procedure, which enables sensitive detection of inflammatory changes. It may be used to simultaneously obtain both precise anatomical and molecular information in order to comprehensively characterize diseases. The glucose analogue 18F-fluorodeoxyglucose (FDG) represents a universally applicable radiotracer for imaging of inflammatory processes. Its accumulation in tissues can be semiquantitatively characterized by use of standardized uptake values (SUV). In principle, a broad spectrum of infectious and non-infectious inflammatory and malignant diseases can be imaged. 18F-FDG PET/CT has become a valuable modality and is increasingly being used for evaluation of large vessel vasculitis and for evaluation of elevated systemic inflammatory markers without known cause. Beside the radiotracer 18F-FDG, other radiopharmaceuticals enable a non-invasive analysis of additional parameters of inflammatory disorders, such as other metabolic pathways or the expression of surface receptors.

Identification and Quantification of Precursory Changes of Rheumatoid Vasculitis in the Dorsalis Pedis Artery.

OBJECTIVE: Rheumatoid arthritis (RA) is a systemic connective tissue autoimmune disease that can infiltrate arterial walls. The delay in diagnosis and treatment of rheumatoid vasculitis (RV) in patients with RA may lead to irreversible damage to the arterial walls of small-to-medium vessels, which has serious and devastating consequences, most notably lung and cardiac damage. In this work an ultrasound image-based biomarker was developed to detect precursory changes in RV. METHODS: The ground truth was initiated from a medical diagnosis of RA, with arterial wall thickening of the proximal dorsalis pedis artery (DPA) indicating precursory changes of RV identified with ultrasound scanning. Ultrasound images of the DPA from 49 healthy subjects in the control group and 46 patients in the RA group were obtained. In total, 187 texture features were extracted from the images, followed by principal component analysis and linear discriminant analysis. RESULTS: The proposed biomarker detected a significant difference between the two groups (p = 5.74 × 10-18) with an area under the receiver operating characteristic curve of 0.85. Ten major textural features contributing most heavily to the biomarker were identified, with these textures being consistent with clinical observations of RV identified in previous studies. Interscan reproducibility was assessed by computing the biomarker twice based on repeated scans of each ankle. High interscan reproducibility was demonstrated by a strong and significant Pearson's coefficient (r = 0.85, p < 0.01) between the two repeated measurements of the proposed biomarker. CONCLUSION: The proposed biomarker can discriminate image textural differences seen in images acquired from RA patients, demonstrating precursory changes in RV compared with healthy controls. The major discriminative features identified in this study may facilitate the early identification and treatment of RV.

18 F-fluorodeoxyglucose positron emission tomography/computed tomography in patients with polymyalgia rheumatica: Screening for vasculitis. / 18 F-FDG PET/TC en pacientes con polimialgia reumática: despistando vasculitis.

OBJECTIVE: Polymyalgia rheumatica (PR) can be associated with large vessel vasculitis (LVV). We evaluate the diagnostic role of 18F-fluorodeoxyglucose positron emission tomography/computed tomography (FDG PET/CT) and its impact on the treatment of LVV associated with PR. MATERIALS AND METHODS: Retrospective study of patients diagnosed with PR. Data was collected from health records. Blood analysis included acute-phase reactants (APR), C-reactive protein (CRP) and erythrocyte sedimentation rate. An 18F-FDG PET/CT scan was performed in those patients whose symptoms persisted, in those with elevated APR, those who required higher doses of steroids or those who had atypical features of PR (low-grade fever, weight loss, among others). RESULTS: Twenty-three were eligible; 48% (n = 11) of the patients were diagnosed with LVV associated with PR. The site was heterogeneous, but mostly involved the aorta. In 80% of the patients with LVV, a disease-modifying antirheumatic drug was added to their treatment. Elevated CRP values were associated with the likelihood of presenting LVV. CONCLUSIONS: LVV is not uncommon, clinical features and elevated CRP levels should raise suspicion of LVV associated with PR. 18F-FDG PET/CT is useful in identifying LVV associated with PR.

Implementation and role of modern musculoskeletal imaging in rheumatological practice in member countries of EULAR.

Objectives: To document the current training, implementation and role of modern musculoskeletal imaging techniques: ultrasound, magnetic resonance imaging, computed tomography and positron emission tomography, among rheumatologists in the member countries of the EULAR. Methods: English-language questionnaires for each imaging modality developed by a EULAR task force were sent out to national and international scientific societies as well as imaging experts in the given modalities involved in research and/or training. The surveys were distributed via an online survey tool (SurveyMonkey). Simple descriptive and summary statistics were calculated from the responses. Results: More than 90% of ultrasound (US) experts reported the availability of a US unit in their department. Suspicion of rheumatoid arthritis and spondyloarthritides were the main clinical indications for performing US for diagnostic purposes. Suspicion of sacroiliitis and degenerative spine disease were the most common indications to perform magnetic resonance imaging (MRI) or computed tomography (CT) for diagnostic purposes, while positron emission tomography was mainly performed to diagnose large vessel vasculitis and to investigate fever of unknown origin. The reported percentage of rheumatologists performing US was highly variable, ranging from more than 80% in 6% of countries to less than 10% in 15% of countries. The majority of experts (77%) reported that their national rheumatology societies organise musculoskeletal US courses, while courses in MRI or CT organised by the national rheumatology societies were less commonly reported (29% and 8%, respectively). Conclusions: Rheumatologists in Europe utilise modern imaging techniques; however, access to the techniques and training offered is varied.