MRI of shoulder girdle in polymyalgia rheumatica: inflammatory findings and their diagnostic value.

BACKGROUND: Non-synovial inflammation as detected by MRI is characteristic in polymyalgia rheumatica (PMR) with potentially high diagnostic value. OBJECTIVE: The objective is to describe inflammatory MRI findings in the shoulder girdle of patients with PMR and discriminate from other causes of shoulder girdle pain. METHODS: Retrospective study of 496 contrast-enhanced MRI scans of the shoulder girdle from 122 PMR patients and 374 non-PMR cases. Two radiologists blinded to clinical and demographic information evaluated inflammation at six non-synovial plus three synovial sites for the presence or absence of inflammation. The prevalence of synovial and non-synovial inflammation, both alone and together with clinical information, was tested for its ability to differentiate PMR from non-PMR. RESULTS: A high prevalence of non-synovial inflammation was identified as striking imaging finding in PMR, in average 3.4±1.7, mean (M)±SD, out of the six predefined sites were inflamed compared with 1.1±1.4 (M±SD) in non-PMR group, p<0.001, with excellent discriminatory effect between PMR patients and non-PMR cases. The prevalence of synovitis also differed significantly between PMR patients and non-PMR cases, 2.5±0.8 (M±SD) vs 1.9±1.1 (M±SD) out of three predefined synovial sites, but with an inferior discriminatory effect. The detection of inflammation at three out of six predefined non-synovial sites differentiated PMR patients from controls with a sensitivity/specificity of 73.8%/85.8% and overall better performance than detection of synovitis alone (sensitivity/specificity of 86.1%/36.1%, respectively). CONCLUSION: Contrast-enhanced MRI of the shoulder girdle is a reliable imaging tool with significant diagnostic value in the assessment of patients suffering from PMR and differentiation to other conditions for shoulder girdle pain.

Desenmascarando la polimialgia reumática, papel de la Medicina Nuclear / Decoding polymyalgia rheumatica, the role of Nuclear Medicine Imaging

La polimialgia reumática (PMR) es una enfermedad inflamatoria de las articulaciones que se presenta en pacientes mayores de 50 años con dolor y rigidez matutina prolongada en las cinturas del hombro y la cadera y en el cuello. La falta de hallazgos clínicos específicos, signos de laboratorio, biomarcadores y métodos de imagen establecidos dificulta el diagnóstico de los pacientes con esta enfermedad. La 18F-FDG PET/TC es una técnica de imagen funcional que constituye una herramienta consolidada en Oncología y que también ha demostrado su utilidad en el campo de las enfermedades inflamatorias. El objetivo de este trabajo es presentar evidencia bibliográfica sobre el uso de métodos de imagen molecular como la PET/TC para el diagnóstico precoz, la evaluación de la actividad de la enfermedad y la respuesta terapéutica en la PMR. Al mismo tiempo, se consideran las ventajas, las desventajas y las contraindicaciones de otros métodos (AU)

Polymyalgia rheumatica (PMR) is an inflammatory joint disease that presents in patients older than 50 years with prolonged morning pain and stiffness in the shoulder and hip joints and neck. The lack of specific clinical findings, laboratory signs, biomarkers and established imaging methods makes it difficult to diagnose patients with this disease. 18F-FDG PET/CT is a functional imaging technique that is an established tool in oncology and has also proven useful in the field of inflammatory diseases. The aim of this paper is to present literature evidence on the use of molecular imaging methods such as PET/CT for early diagnosis, assessment of disease activity and therapeutic response in PMR. At the same time, the advantages, disadvantages and contraindications of other methods are considered (AU)

The usefulness of 18F-FDG-PET/CT in detecting musculoskeletal and vascular involvement in patients with polymyalgia rheumatica receiving glucocorticoids.

OBJECTIVE: Fluorine-18-fluorodeoxyglucose (18F-FDG) PET/CT is a promising diagnostic tool for polymyalgia rheumatica (PMR) and large vessel vasculitis (LVV). PET/CT performance is recommended before the onset of steroid therapy because glucocorticoids (GC) may decrease the intensity of FDG uptake. However, this is not always possible in clinical practice. Our aim was to assess if PET/CT could be also useful to detect musculoskeletal and vascular involvement in patients receiving GC. METHODS: Single-center study of patients with PMR diagnosis based on 2012 EULAR/ACR criteria who underwent a PET/CT scan due to LVV suspicion. We compared the musculoskeletal and vascular FDG uptake between two groups: (a) steroid-naïve and (b) steroid-resistant patients. A sub-analysis was conducted in patients who were receiving GC to discern if the cumulative prednisone dose influences the FDG uptake. RESULTS: We evaluated 75 patients (27 men/ 48 women); mean age±SD: 68.2 ± 10.7 years. PET/CT was performed in 14 steroid-naïve and 61 steroid-resistant patients. Patients under GC had received a median cumulative prednisone dose of 1.8 [0.6-3.9] g. The pattern of musculoskeletal FDG uptake was similar in steroid-naïve and steroid-resistant patients. FDG uptake in the vessel wall was more frequently detected in steroid-naïve patients. However, PET/ CT was also useful to detect LVV in 62.3 % of the patients who were receiving GC. The percentage of patients who had positive PET/CT scans tended to decrease with higher cumulative prednisone doses. CONCLUSION: Even though GC therapy may decrease the 18-FDG uptake, PET/CT continues to be a useful tool to detect musculoskeletal and LVV involvement in PMR.

Diagnostic value of 18F-fluorodeoxyglucose positron emission tomography and computed tomography for differentiating polymyalgia rheumatica and rheumatoid arthritis: Using classification and regression tree analysis.

OBJECTIVES: Determining which sites were important to differentiate polymyalgia rheumatica (PMR) from rheumatoid arthritis (RA) using 18F-fluorodeoxyglucose (FDG) positron emission tomography and computed tomography (PET-CT) is challenging. METHODS: Patients with PMR or RA who were undergoing PET-CT were recruited at two mutual-aid hospitals in Japan between 2009 and 2018. Classification and regression tree (CART) analyses were performed to identify FDG uptake patterns that differentiated PMR from RA. RESULTS: We enrolled 35 patients with PMR and 46 patients with RA. Univariate CART analysis showed that FDG uptake in the shoulder joints, spinous processes of the lumbar vertebrae, pubic symphysis, sternoclavicular joints, ischial tuberosities, greater trochanters, and hip joints differentiated PMR from RA. Multivariate CART analysis revealed that FDG uptake by at least one of the ischial tuberosities had the highest diagnostic value for distinguishing PMR from RA (sensitivity, 77.1%; specificity, 82.6%). We performed the same CART analysis to patients who had not undergone treatment (PMR, n = 28; RA, n = 9). Similar results were obtained, and sensitivity and specificity were increased (sensitivity, 89.3%; specificity, 88.8%). CONCLUSIONS: In PET-CT, FDG uptake by at least one of the ischial tuberosities best discriminates between PMR and RA.

[18F]FDG PET/CT for therapeutic assessment of Abatacept in early-onset polymyalgia rheumatica.

PURPOSE: Evaluate the benefit of 2-deoxy-2-[18F]-fluoro-D-glucose ([18F] FDG) positron emission tomography/computed tomography (PET/CT) for the therapeutic assessment of Abatacept (ABA) as first-line therapy in early-onset polymyalgia rheumatica (PMR) patients. METHODS: This was an ancillary study of ALORS trial (Abatacept in earLy Onset polymyalgia Rheumatica Study) assessing the ability of ABA versus placebo to achieve low disease activity (C-Reactive Protein PMR activity score (CRP PMR-AS) ≤ to 10) without glucocorticoid (GC) at week 12 in patients with early-onset PMR. The patients underwent [18F] FDG PET/CT at baseline and after 12 weeks of treatment. Responses to treatments were evaluated according to CRP PMR-AS, Erythrocyte Sedimentation Rate (ESR) PMR-AS, Clin PMR-AS, and CRP-Imputed (Imput-CRP) PMR-AS. Quantitative score by maximal standardized uptake value (SUVmax) and combined qualitative scores according to liver uptake (Leuven, Leuven/Groningen, and Besançon Scores) were used for assessment of [18F] FDG uptake in regions of interest (ROI) usually affected in PMR. Student's t-test was applied to evaluate the clinical, biological, and [18F] FDG uptake variation difference in ABA and placebo groups between W0 and W12. Subgroup analysis by GC rescue was performed. RESULTS: At W12, there was no significant difference according to SUVmax between the ABA and the placebo groups in all ROI. Subgroup analysis according to GC administration demonstrated a significant (p 0.047) decrease in SUVmax within the left sternoclavicular joint ROI in the ABA group (- 0.8) compared to the placebo group (+ 0.6) without GC rescue. Other results did not reveal any significant difference between the ABA and placebo groups. According to combined qualitative scores, there was no significant difference between ABA and placebo groups for the direct comparison analysis and subgroup analysis according to GC rescue. CONCLUSION: [18F] FDG PET/CT uptake did not decrease significantly after ABA compared to placebo in anatomical areas usually affected in PMR patients. These results are correlated with the clinical-biological therapeutic assessment. CLINICAL TRIAL REGISTRATION: The study was approved by the appropriate ethics committee (CPP Sud-Est II Ref CPP: 2018-33), and all patients gave their written informed consent before study enrollment. The protocol was registered on Clinicaltrials.gov (NCT03632187).

Decoding polymyalgia rheumatica, the role of Nuclear Medicine Imaging.

Polymyalgia rheumatica (PMR) is an inflammatory joint disease that presents in patients older than 50 years with prolonged morning pain and stiffness in the shoulder and hip joints and neck. The lack of specific clinical findings, laboratory signs, biomarkers and established imaging methods makes it difficult to diagnose patients with this disease. 18F-FDG PET/CT is a functional imaging technique that is an established tool in oncology and has also proven useful in the field of inflammatory diseases. The aim of this paper is to present literature evidence on the use of molecular imaging methods such as PET/CT for early diagnosis, assessment of disease activity and therapeutic response in PMR. At the same time, the advantages, disadvantages and contraindications of other methods are considered.

Assessing the feasibility of SUVindex (a metric derived from FDG PET/CT) for the diagnosis of polymyalgia rheumatica.

AIM: To evaluate the feasibility of standard uptake value (SUV) index (ratio lesional maximum SUV [SUVmax] to liver mean SUV [SUVmean]) as a metabolic parameter for diagnosing polymyalgia rheumatica (PMR). MATERIALS AND METHODS: A retrospective group of patients with PMR and controls with symptoms similar to PMR but diagnosed with other diseases. Semiquantitative and qualitative analysis of 2-[18F]-fluoro-2-deoxy-d-glucose (18F-FDG) uptake at 18 sites was undertaken for all patients. The diagnostic value of positron-emission tomography/computed tomography (PET/CT) for PMR was assessed by R software using logistic regression and a generalised additive model (GAM). All images were examined independently by two nuclear medicine physicians with extensive work experience. RESULTS: The characteristic sites of PMR were the ischial tuberosity, interspinous bursa, periarticular hip, and symphysis pubis enthesis. The area under the curve (AUC) of the characteristic site SUV index was 0.930, and the best cut-off value was 1.685 with a sensitivity of 84.6% and a specificity of 92.6%. After adjusting for potential confounders, the probability of PMR diagnosis increased as the characteristic site SUV index increased and there was a nonlinear correlation between the two. When the characteristic site SUV index was ≥2.56, the probability of PMR gradually reached the threshold effect, which was as high as 90% or more. CONCLUSION: The characteristic site SUV index is an independent factor for diagnosing PMR, and PMR should be highly suspected when it is ≥ 1.685. Nonetheless, it is important to note that these findings are based on an initial retrospective single-centre study and require external validation and further prospective evaluation before being translated into clinical practice.

Clinical, laboratory and ultrasonographic findings at baseline predict long-term outcome of polymyalgia rheumatica: a multicentric retrospective study : Polymyalgia rheumatica predicted by ultrasonographic findings polymyalgia rheumatica outcome predicted early by ultrasound.

To assess the rate of PMR who, during the follow-up, undergo a diagnostic shift as well as to assess which clinical, laboratory and US findings are associated to a diagnostic shift and predict the long-term evolution of PMR. All PMR followed-up for at least 12 months were included. According to the US procedures performed at diagnosis, patients were subdivided into four subgroups. Clinical data from follow-up visits at 12, 24, 48 and 60 months, including a diagnostic shift, the number of relapses and immunosuppressive and steroid treatment, were recorded. A total of 201 patients were included. During the follow-up, up to 60% had a change in diagnosis. Bilateral LHBT was associated with persistence in PMR diagnosis, whereas GH synovitis and RF positivity to a diagnostic shift. Patients undergoing diagnostic shift had a higher frequency of GH synovitis, shoulder PD, higher CRP, WBC, PLT and Hb and longer time to achieve remission, while those maintaining diagnosis had bilateral exudative LHBT and SA-SD bursitis, higher ESR, lower Hb and shorter time to remission. Cluster analysis identified a subgroup of older patients, with lower CRP, WBC, PLT and Hb, lower PD signal or peripheral synovitis who had a higher persistence in PMR diagnosis, suffered from more flares and took more GCs. Most PMR have their diagnosis changed during follow-up. The early use of the US is associated with a lower dosage of GCs. Patients with a definite subset of clinical, laboratory and US findings seem to be more prone to maintain the diagnosis of PMR.

Ultrasound description and follow up of painful cervical interspinous bursitis in a Polymyalgia Rheumatica patient - a case report.

We present a Polymyalgia Rheumatica (PMR) case with active Cervical Interspinous Bursitis (CIB) causing debilitat-ing neck pain as the most intensive symptom of the disease as reported by the patient. CIB was diagnosed and followed by Musculoskeletal Ultrasound (MSUS). MSUS examination of patient's posterior cervical region reviled well demarcated an-/ hypoechoic lesions around and cranially of the spinous processes of the sixth and seventh cervical vertebra. The initial detailed sonographic characteristics of the CIB are described, as well as the evolution of lesions size and extent with the treatment and patient's clinical improvement. To our knowledge this is the rst detailed sonographic description of CIB in PMR.

Role of 18F-FDG PET/CT in Large Vessel Vasculitis and Polymyalgia Rheumatica.

Systemic vasculitides comprise a group of autoimmune diseases affecting blood vessels, including large vessel vasculitis (LVV) and medium-sized vessel vasculitis such as giant cell arteritis (GCA) and Takayasu arteritis (TAK). GCA frequently overlaps with polymyalgia rheumatica (PMR), a rheumatic inflammatory condition affecting bursae, tendons or tendon sheaths, and joints. 18F-FDG PET/CT plays an important role in the diagnostic work-up of GCA, PMR, and TAK and is increasingly used to monitor treatment response. This continuing education article provides up-to-date guidance on the role of 18F-FDG PET/CT in patients with LVV, medium-sized vessel vasculitis, and PMR. It provides a general introduction on the clinical presentation and challenges in the diagnostic work-up of LVV and medium-sized vessel vasculitis, with a focus on the 2 major LVV subtypes: GCA, including PMR, and TAK. Next, practice points to perform and interpret the results of 18F-FDG PET/CT are described in line with the published procedure recommendations. Furthermore, the diagnostic performance and its role for treatment monitoring are discussed, taking into account recent international recommendations for the use of imaging in LVV and medium-sized vessel vasculitis in clinical practice. This is illustrated by several clinically representative PET/CT scan examples. Lastly, knowledge of limitations and pitfalls is essential to understand the role of 18F-FDG PET/CT in LVV, medium-sized vessel vasculitis, and PMR. Challenges and opportunities, as well as future research and conclusions, are highlighted. Learning objectives provide up-to-date guidance for the role of 18F-FDG PET/CT in patients with suspected LVV, medium-sized vessel vasculitis, and PMR.

Do statins decrease vascular inflammation in patients at risk for large-vessel vasculitis? A retrospective observational study with FDG-PET/CT in polymyalgia rheumatica, giant cell arteritis and fever of unknown origin.

OBJECTIVES: [18F] Fluorodeoxyglucose (FDG) positron emission tomography/computed tomography (PET/CT) can detect the presence of large-vessel vasculitis (LVV) in patients with polymyalgia rheumatica (PMR), giant cell arteritis (GCA) and fever of unknown origin (FUO). The aim of this study was to evaluate whether statins could reduce FDG-PET/CT-assessed vascular inflammation in this group of patients. METHODS: Clinical, demographic, laboratory data, current pharmacological treatments, and cardiovascular risk factors of patients with PMR, GCA and FUO, who underwent FDG-PET/CT, were recorded. FDG uptake was measured at prespecified arterial sites with the mean standardised uptake value (SUV), and with a qualitative visual score, summed up to obtain a total vascular score (TVS). LVV was diagnosed if arterial FDG visual uptake was equal or higher of liver uptake. RESULTS: 129 patients were included (96 with PMR, 16 with GCA, 13 with both PMR and GCA, and 4 with FUO), of whom 75 (58.1%) showed LVV. Twenty out of 129 (15.5%) patients were taking statins. TVS was significantly lower in patients treated with statins (p=0.02), especially in the aorta (p=0.023) and femoral arteries (p=0.027). CONCLUSIONS: Our preliminary results suggest that statins may exert a potential protective role on vascular inflammation in patients with PMR and GCA. Statin use could spuriously decrease FDG uptake of the vessel walls.

FDG PET/CT Imaging of Severe Polymyalgia Rheumatica.

ABSTRACT: A 68-year-old woman was referred for an 18 F-FDG PET/CT for evaluation of arthralgia and raised inflammatory markers, which demonstrated intense FDG activity (SUV max , 25.5) at numerous periarticular and extra-articular sites including the cervical and lumbar interspinous bursae, lumbar facet joints, bilateral ischial tuberosities, and greater trochanters and the aorta consistent with active polymyalgia rheumatica.

Usefulness of ultrasound as a predictor of elderly-onset rheumatoid arthritis with polymyalgia rheumatica-like onset.

OBJECTIVES: Differentiation between polymyalgia rheumatica (PMR) and elderly-onset rheumatoid arthritis (EORA), especially in elderly patients, is often difficult due to similarities in symptoms and serological kinetics. In this study, we aimed to analyse the predictors of EORA with PMR-like onset. METHODS: Seventy-two patients diagnosed with PMR, who attended our hospital for routine care and underwent musculoskeletal ultrasonography at that time were evaluated. Synovitis was evaluated semi-quantitatively (0-3) by grey scale (GS) and power Doppler (PD) in 24 joints [both hands (wrist, metacarpophalageal, and proximal interphalangeal joints) and both shoulder joints]. RESULTS: Overall, 18 patients had rheumatoid arthritis (25.0%); the mean age was 75.0 years, and 34.7% and 65.3% were male and female, respectively. In PMR and PMR/EORA groups, multivariate logistic analysis showed that rheumatoid factor positivity, GS ≥2 of hand joints, and PD ≥1 of hand joints were independent factors with significant differences. At least one of the three factors had a sensitivity of 88.9% and specificity of 92.6%. CONCLUSIONS: The presence of at least one of the criteria: rheumatoid factor positivity, GS ≥ 2, and PD ≥ 1 of hand joints, suggested the possibility of developing EORA within 1 year of PMR diagnosis.

Fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography in polymyalgia rheumatica: an observational study.

OBJECTIVES: Polymyalgia rheumatica (PMR) is an inflammatory disease with a diagnosis that is sometimes difficult to establish. Fluorine-18 fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT) might be helpful. We analysed the usefulness of 18F-FDG PET/CT for the diagnosis of PMR. METHODS: This was an observational retrospective study of individuals with PMR who underwent 18F-FDG PET/CT and a control group. We assessed clinical and 18F-FDG PET/CT characteristics. Sixteen sites were studied. The number of sites with significant FDG uptake, the mean maximum standardised uptake value (SUVmax) and the highest SUVmax value were assessed for each patient. RESULTS: Data for 123 patients with PMR (37 with corticosteroids [CSTs] use) were analysed; 85 had new-onset PMR. As compared with the 75 controls, patients with new-onset PMR had higher mean ± SD number of sites with significant FDG uptake (11.3 ± 3.3 vs. 0.9 ± 1.1, p<0.001) and higher SUVmax scores (p<0.001). A cut-off of 5 hypermetabolic sites provided sensitivity of 96.5% and specificity 100%. For the total SUVmax score, a cut-off of 3 had the best sensitivity (92.6%) and specificity (86.1%). As compared with PMR patients using CSTs, those who were CST-naive had significantly higher CRP level (p<0.001), number of sites with significant FDG uptake (p<0.001) and SUVmax scores (p<0.01). In contrast, large-vessel vasculitis was more frequent in patients receiving CSTs than CST-naive patients (27% vs. 8%, p<0.01). CONCLUSIONS: The number of hypermetabolic sites or SUVmax quantification might be useful for PMR diagnosis, and CSTs might affect the results of 18F-FDG PET/CT.

Subclinical giant cell arteritis in new onset polymyalgia rheumatica A systematic review and meta-analysis of individual patient data.

OBJECTIVES: To determine the prevalence and predictors of subclinical giant cell arteritis (GCA) in patients with newly diagnosed polymyalgia rheumatica (PMR). METHODS: PubMed, Embase, and Web of Science Core Collection were systematically searched (date of last search July 14, 2021) for any published information on any consecutively recruited cohort reporting the prevalence of GCA in steroid-naïve patients with PMR without cranial or ischemic symptoms. We combined prevalences across populations in a random-effect meta-analysis. Potential predictors of subclinical GCA were identified by mixed-effect logistic regression using individual patient data (IPD) from cohorts screened with PET/(CT). RESULTS: We included 13 cohorts with 566 patients from studies published between 1965 to 2020. Subclinical GCA was diagnosed by temporal artery biopsy in three studies, ultrasound in three studies, and PET/(CT) in seven studies. The pooled prevalence of subclinical GCA across all studies was 23% (95% CI 14%-36%, I2=84%) for any screening method and 29% in the studies using PET/(CT) (95% CI 13%-53%, I2=85%) (n=266 patients). For seven cohorts we obtained IPD for 243 patients screened with PET/(CT). Inflammatory back pain (OR 2.73, 1.32-5.64), absence of lower limb pain (OR 2.35, 1.05-5.26), female sex (OR 2.31, 1.17-4.58), temperature >37° (OR 1.83, 0.90-3.71), weight loss (OR 1.83, 0.96-3.51), thrombocyte count (OR 1.51, 1.05-2.18), and haemoglobin level (OR 0.80, 0.64-1.00) were most strongly associated with subclinical GCA in the univariable analysis but not C-reactive protein (OR 1.00, 1.00-1.01) or erythrocyte sedimentation rate (OR 1.01, 1.00-1.02). A prediction model calculated from these variables had an area under the curve of 0.66 (95% CI 0.55-0.75). CONCLUSION: More than a quarter of patients with PMR may have subclinical GCA. The prediction model from the most extensive IPD set has only modest diagnostic accuracy. Hence, a paradigm shift in the assessment of PMR patients in favour of implementing imaging studies should be discussed.

Measurement Properties of the Polymyalgia Rheumatica Activity Score: A Systematic Literature Review.

OBJECTIVE: To perform a COnsensus-based Standards for the selection of health Measurement INstruments (COSMIN)-based systematic literature review of measurement properties of the Polymyalgia Rheumatica Activity Score (PMR-AS). METHODS: PubMed, EMBASE, and CINAHL were broadly searched. English full-text articles, with (quantitative) data on ≥ 5 patients with PMR using the PMR-AS were selected. Seven hypotheses for construct validity and 3 for responsiveness, concerning associations with erythrocyte sedimentation rate, physical function, quality of life, clinical disease states, ultrasound, and treatment response, were formulated. We assessed the structural validity, internal consistency, reliability, and measurement error, or the hypotheses on construct validity or responsiveness of the PMR-AS based on COSMIN criteria. RESULTS: Out of the identified 26 articles that used the PMR-AS, we were able to use 12 articles. Structural validity, internal consistency, construct validity, and responsiveness were assessed in 1, 2, 8, and 3 articles, respectively. Insufficient evidence was found to confirm structural validity and internal consistency. No data were found on reliability or measurement error. Although 60% and 67% of hypotheses tested for construct validity and responsiveness, respectively, were confirmed, there was insufficient evidence to meet criteria for good measurement properties. CONCLUSION: While there is some promising evidence for construct validity and responsiveness of the PMR-AS, it is lacking for other properties and, overall, falls short of criteria for good measurement properties. Therefore, further research is needed to assess its role in clinical research and care.

A Peculiar 18 F-FDG Spinal Uptake Helps Diagnosis and Effective Treatment of Polymyalgia Rheumatica : "The Corset Sign".

ABSTRACT: Polymyalgia rheumatica is the most common inflammatory rheumatic disease in elderly people, usually develops in patients older than 50 years, more frequently in females. An emerging imaging tool in the diagnostic workup of this condition is whole-body PET/CT, which allows an overall assessment of the articular and extra-articular structures involved.