The Role of Musculoskeletal Ultrasound in the Rheumatoid Arthritis Continuum

Current Use and Barriers to Point-of-Care Ultrasound in Rheumatology: A National Survey of VA Medical Centers

INTRODUCTION

Point-of-care ultrasound (POCUS) can assist rheumatologists in monitoring disease activity, establishing diagnoses, and guiding procedural interventions. POCUS use has been increasing, but little is known about current use and barriers among rheumatologists. The purpose of this study was to characterize current POCUS use, training needs, and barriers to use among rheumatologists in practice.

METHODS

A prospective observational study of all Veterans Affairs (VA) medical centers was conducted using a web-based survey sent to all chiefs of staff and rheumatology chiefs about current POCUS use, training needs, barriers, and policies.

RESULTS

All chiefs of staff (n = 130) and rheumatology chiefs at VA medical centers (n = 95) were surveyed with 100% and 84% response rates, respectively. The most common diagnostic POCUS applications were evaluation of synovitis, joint effusion, tendinopathies, bursitis, and rotator cuff. The most common procedural applications were arthrocentesis and joint, bursa, and tendon injection. Most rheumatology chiefs (69%) expressed interest in training for their group. The most common barriers to POCUS use were lack of trained providers (68%), funding for training (54%), training opportunities (38%), funding for travel (38%), and ultrasound equipment (31%). Lack of POCUS infrastructure was common, and few facilities had POCUS policies (20%), image archiving (25%), or quality assurance processes (6%).

CONCLUSION

Currently, half of rheumatology groups use diagnostic and procedural ultrasound applications. Most rheumatology groups desire training, and lack of training and equipment were the most common barriers to ultrasound use. Deliberate investment is needed in ultrasound training and infrastructure for systematic adoption of POCUS in rheumatology. Graphical Abstract available for this article.

TRIAL REGISTRATION

NCT03296280.

Rapid onset pembrolizumab-induced inflammatory arthritis diagnosed using musculoskeletal ultrasound

Immune checkpoint inhibitors have revolutionised the treatment of cancer. While very effective, they commonly cause a wide spectrum of immune-related adverse events. These immune-related adverse events can be fatal and often have significant effects on quality of life. They therefore require prompt recognition and management. We report the case of a woman presenting with widespread joint pain and stiffness 6 hours after her first pembrolizumab infusion. She had no joint swelling on physical examination but an ultrasound scan revealed widespread musculoskeletal inflammation, confirming the diagnosis of inflammatory arthritis. To the best of our knowledge, this is the fastest reported inflammatory arthritis onset following immune checkpoint inhibitor treatment. It highlights the importance of timely imaging in patients on immune checkpoint inhibitors who present with new non-specific musculoskeletal pain. Her symptoms improved dramatically with intramuscular triamcinolone injection.

Rheumatoid arthritis

Rheumatoid arthritis is a chronic, systemic, autoimmune inflammatory disease that mainly affects the joints and periarticular soft tissues. In this Seminar, we provide an overview of the main aspects of rheumatoid arthritis. Epidemiology and advances in the understanding of rheumatoid arthritis pathogenesis will be reviewed. We will discuss the clinical manifestations of rheumatoid arthritis, classification criteria, and the value of imaging in the diagnosis of the disease. The advent of new medications and the accumulated scientific evidence demand continuous updating regarding the diagnosis and management, including therapy, of rheumatoid arthritis. An increasing number of patients are now able to reach disease remission. This major improvement in the outcome of patients with rheumatoid arthritis has been determined by a combination of different factors (eg, early diagnosis, window of opportunity, treat-to-target strategy, advent of targeted disease-modifying antirheumatic drugs, and combination therapy). We will discuss the updated recommendations of the two most influential societies for rheumatology worldwide (ie, the American College of Rheumatology and European Alliance of Associations for Rheumatology) for the management of rheumatoid arthritis. Furthermore, controversies (ie, the role of glucocorticoids in the management of rheumatoid arthritis and safety profile of Janus kinase inhibitors) and outstanding research questions, including precision medicine approach, prevention, and cure of rheumatoid arthritis will be highlighted.

Correlation analysis and clinical significance of Musculoskeletal Ultrasound semi-quantitative grading with bone salt metabolism, Rheumatoid factor and Erythrocyte Sedimentation rate in patients with Rheumatoid Arthritis

Objective

To determine the correlation and clinical significance of musculoskeletal ultrasound semi-quantitative grading with bone salt metabolism, rheumatoid factor and erythrocyte sedimentation rate (ESR) in patients with rheumatoid arthritis.

Methods

This is a clinical comparative study. A total of 240 patients with rheumatoid arthritis admitted to Baoding NO.1 Central Hospital were selected according to the DAS28 score of rheumatoid arthritis, and were divided into four groups, with 60 cases in each group from May 2020 to May 2022. The differences and correlation of musculoskeletal ultrasound semi-quantitative grading, bone metabolism indicators, erythrocyte sedimentation rate and rheumatoid factor among the four groups were statistically analyzed.

Results

The scores of bone erosion, synovial hyperplasia, joint effusion and intrasynovial blood flow in Group-H were significantly higher than those in Group-R, L and M, with statistically significant differences(p=0.00). The procollagen Type-1 N-terminal propeptide(P1NP), bone-specific alkaline phosphatase(BALP) and osteoprotegerin(OPG) in Group-H were significantly lower than those in Group-R, L and M, with statistically significant differences(p=0.00); The tartrate-resistant acid phosphatase(TRAC) in Group-H was significantly higher than that in Group-R, L and M, with a statistically significant difference(p=0.00). The levels of RF and ESR in Group-H were significantly higher than those in Group-R, L and M, with statistically significant differences(p=0.00).

Conclusion

Musculoskeletal ultrasound semi-quantitative grading is correlated with the level of bone salt metabolism, rheumatoid factor and ESR in patients with rheumatoid arthritis. It can be combined with laboratory examination to objectively judge the severity of the course of rheumatoid arthritis.

Identification of MYH9 as a key regulator for synoviocyte migration and invasion through secretome profiling

OBJECTIVES

'Invasive pannus' is a pathological hallmark of rheumatoid arthritis (RA). This study aimed to investigate secretome profile of synovial fibroblasts of patients with RA (RA-FLSs), a major cell type comprising the invasive pannus.

METHODS

Secreted proteins from RA-FLSs were first identified using liquid chromatography-tandem mass spectrometry analysis. Ultrasonography was performed for affected joints to define synovitis severity at the time of arthrocentesis. Expression levels of myosin heavy chain 9 (MYH9) in RA-FLSs and synovial tissues were determined by ELISA, western blot analysis and immunostaining. A humanised synovitis model was induced in immuno-deficient mice.

RESULTS

We first identified 843 proteins secreted from RA-FLSs; 48.5% of the secretome was associated with pannus-driven pathologies. Parallel reaction monitoring analysis of the secretome facilitated discovery of 16 key proteins related to 'invasive pannus', including MYH9, in the synovial fluids, which represented synovial pathology based on ultrasonography and inflammatory activity in the joints. Particularly, MYH9, a key protein in actin-based cell motility, showed a strong correlation with fibroblastic activity in the transcriptome profile of RA synovia. Moreover, MYH9 expression was elevated in cultured RA-FLSs and RA synovium, and its secretion was induced by interleukin-1β, tumour necrosis factor α, toll-like receptor ligation and endoplasmic reticulum stimuli. Functional experiments demonstrated that MYH9 promoted migration and invasion of RA-FLSs in vitro and in a humanised synovitis model, which was substantially inhibited by blebbistatin, a specific MYH9 inhibitor.

CONCLUSIONS

This study provides a comprehensive resource of the RA-FLS-derived secretome and suggests that MYH9 represents a promising target for retarding abnormal migration and invasion of RA-FLSs.

Predicting Inflammatory Arthritis in At-Risk Persons: Development of Scores for Risk Stratification

BACKGROUND

Inflammatory arthritis (IA) is an immune-related condition defined by the presence of clinical synovitis. Its most common form is rheumatoid arthritis.

OBJECTIVE

To develop scores for predicting IA in at-risk persons using multidimensional biomarkers.

DESIGN

Prospective observational cohort study.

SETTING

Single-center, Leeds, United Kingdom.

PARTICIPANTS

Persons with new musculoskeletal symptoms, a positive test result for anticitrullinated protein antibodies, and no clinical synovitis and followed for 48 weeks or more or until IA occurred.

MEASUREMENTS

A simple score was developed using logistic regression, and a comprehensive score was developed using the least absolute shrinkage and selection operator Cox proportional hazards regression. Internal validation with bootstrapping was estimated, and a decision curve analysis was done.

RESULTS

Of 455 participants, 32.5% (148 of 455) developed IA, and 15.4% (70 of 455) developed it within 1 year. The simple score identified 249 low-risk participants with a false negative rate of 5% (and 206 high-risk participants with a false-positive rate of 72%). The comprehensive score identified 119 high-risk participants with a false-positive rate of 29% (and 336 low-risk participants with a false-negative rate of 19%); 40% of high-risk participants developed IA within 1 year and 71% within 5 years.

LIMITATIONS

External validation is required. Recruitment occurred over 13 years, with lower rates of IA in later years. There was geographic variation in laboratory testing and recruitment availability.

CONCLUSION

The simple score identified persons at low risk for IA who were less likely to need secondary care. The comprehensive score identified high-risk persons who could benefit from risk stratification and preventive measures. Both scores may be useful in clinical care and should also be useful in clinical trials.

PRIMARY FUNDING SOURCE

National Institute for Health and Care Research Leeds Biomedical Research Centre.

Automated segmentation and classification of hand thermal images in rheumatoid arthritis using machine learning algorithms: A comparison with quantum machine learning technique

The aims and objectives of the study were to i) perform image segmentation using a color-based k-means clustering algorithm and feature extraction using binary robust invariant scalable key points (BRISK), maximum stable extremal regions (MSER), features from accelerated segment test (FAST), Harris, and orientated FAST and rotated BRIEF (ORB); ii) compare the performance of classical machine learning techniques such as LogitBoost, Bagging, and SVM with a quantum machine learning technique. For the proposed study, 240 hand thermal images were acquired in the dorsal view and ventral view of both the right and left-hand regions of RA and normal subjects. The hot spot regions from the thermograms were segmented using a color-based k-means clustering technique. The features from the segmented hot spot region were extracted using different feature extraction methods. Finally, normal and RA groups were categorized using LogitBoost, Bagging, and support vector machine (SVM) classifiers. The proposed study used two testing methods, such as 10-fold cross-validation and a percentage split of 80-20%. The LogitBoost classifier outperformed with an accuracy of 93.75% using the 10-fold cross-validation technique compared to other classifiers. Also, the quantum support vector machine (QSVM) obtained a prediction accuracy of 92.7%. Furthermore, the QSVM model reduces the computational cost and training time of the model to classify the RA and normal subjects. Thus, thermograms with classical machine learning and quantum machine learning algorithms could be considered a feasible technique for classifying normal and RA groups.

An ultrasound negative for subclinical synovitis in arthralgia patients: is it helpful in identifying those not developing arthritis?

OBJECTIVE

To investigate the negative predictive value (NPV) of musculoskeletal US (MSUS) in arthralgia patients at risk for developing inflammatory arthritis.

METHODS

An MSUS examination of hands and feet was performed in arthralgia patients at risk for inflammatory arthritis in four independent cohorts. Patients were followed for one-year on the development of inflammatory arthritis. Subclinical synovitis was defined as greyscale ≥2 and/or power Doppler ≥1. NPVs were determined and compared with the prior risks of not developing inflammatory arthritis. Outcomes were pooled using meta-analyses and meta-regression analyses. In sensitivity analyses, MSUS imaging of tender joints only (rather than the full US protocol) was analysed and ACPA stratification applied.

RESULTS

After 1 year 78, 82, 77 and 72% of patients in the four cohorts did not develop inflammatory arthritis. The NPV of a negative US was 86, 85, 82 and 90%, respectively. The meta-analysis showed a pooled non-inflammatory arthritis prevalence of 79% (95% CI 75%, 83%) and a pooled NPV of 86% (95% CI 81, 89%). Imaging tender joints only (as generally done in clinical practice) and ACPA stratification showed similar results.

CONCLUSION

A negative US result in arthralgia has a high NPV for not developing inflammatory arthritis, which is mainly due to the high a priori risk of not developing inflammatory arthritis. The added value of a negative US (<10% increase) was limited.

Whole-Body Macrophage Positron Emission Tomography Imaging for Disease Activity Assessment in Early Rheumatoid Arthritis

OBJECTIVE

To investigate the potential of whole-body positron emission tomography/computed tomography (PET/CT) with a macrophage tracer to image arthritis in patients with early rheumatoid arthritis (RA).

METHODS

Thirty-five previously untreated, clinically active patients with early RA underwent whole-body PET/CT scanning with the macrophage tracer (R)-[¹¹C]PK11195 in addition to clinical assessment (Disease Activity Score in 44 joints [DAS44]). Tracer uptake was assessed quantitatively as standardized uptake values (SUVs). In addition, 2 readers blinded to clinical assessment visually scored tracer uptake in joints. Clinical and PET variables were compared using Cohen , linear regression/correlation, and t tests, where appropriate.

RESULTS

All but 1 patient showed enhanced tracer uptake in at least 1 joint. Twelve percent of all joints (171/1470) were visually positive on the PET scan, most frequently the small joints in feet (40%) and hands (37%), followed by wrists (15%). Correlations of visual scores with clinical findings both at patient and joint levels were absent or weak. In contrast, average SUVs in the hands, feet, and whole body showed significant correlations with DAS44 scores, with the best correlation seen in the feet (R² = 0.29, P < 0.01).

CONCLUSION

Clinically active patients with early RA had increased joint uptake of a macrophage PET tracer, especially in the feet. Quantitative, but not visual PET measures of whole body and joint groups, particularly the feet, showed moderate and statistically significant correlations with clinical outcome.

Comparison of AI-powered 3D automated ultrasound tomography with standard handheld ultrasound for the visualization of the hands-clinical proof of concept

OBJECTIVE

To assess the ability of a newly developed AI-powered ultrasound 3D hand scanner to visualize joint structures in healthy hands and detect degenerative changes in cadaveric hands.

MATERIALS AND METHODS

Twelve individuals (6 males, 6 females, age 43.5 ± 17.8 years) underwent four scans with the 3D ultrasound tomograph (right and left hand, dorsal and palmar, respectively) as well as four sets of handheld ultrasound of predefined anatomic regions. The 3D ultrasound tomographic images and the standard handheld ultrasound images were assessed by two radiologists with regard to visibility of bone contour, joint capsule and space, and tendons. In addition, three cadaveric hands were scanned with the 3D ultrasound tomograph and CT.

RESULTS

Mean scan time for both hands was significantly faster with handheld ultrasound (10 min 30 s ± 95 s) compared to 3D ultrasound tomography (32 min 9 s ± 6 s; p < 0.001). Interreader and intermodality agreement was moderate (0.4 < κ ≤ 0.6) to substantial (0.6 < κ ≤ 0.8). Overall visibility of joint structures was comparable between the modalities at the level of the wrist (p = 0.408), and significantly better with handheld ultrasound at the level of the finger joints and the thumb (both p < 0.001). The 3D ultrasound tomograph was able to detect osteophytes in cadaveric hands which were confirmed by CT.

CONCLUSION

The AI-powered 3D ultrasound tomograph was able to visualize joint structures in healthy hands and singular osteophytes in cadaveric hands. Further technical improvements are necessary to shorten scan times and improve automated scanning of the finger joints and the thumb.

Musculoskeletal ultrasound for treating rheumatoid arthritis to target-a systematic literature review

OBJECTIVE

We aimed to systematically review the literature to retrieve evidence on the diagnostic and prognostic value of musculoskeletal ultrasound for a treat to target (T2T) approach in RA.

METHODS

Eight research questions were developed addressing the role of ultrasound (including different ultrasound scores and elementary lesions) for diagnosis, monitoring and prognosis of RA. PubMed and EMBASE were searched (2005-2020). Articles on RA and reporting data on musculoskeletal ultrasound were included and extracted according to the underlying questions, and risk of bias assessed according to the study design.

RESULTS

Out of 4632 records, 60 articles were included. Due to clinical heterogeneity, meta-analysis was not possible. Ultrasound better predicted disease relapses with respect to clinical examination in patients in remission, while both methods performed similarly in predicting response to therapy, achievement of remission and radiographic progression. Ultrasound was superior to clinical examination in diagnosing joint involvement using another imaging modality, such as magnetic resonance imaging, as reference. Limited ultrasound scores performed like more extensive evaluations for the detection of joint inflammation and for outcome prediction. Higher ultrasound scores of synovitis were linked to poor outcomes at all disease stages, but a specific cut-off distinguishing between low- and high-risk groups did not emerge.

CONCLUSIONS

These data confirm the pivotal role of ultrasound when evaluating synovial inflammation and when identifying RA patients at higher risk of relapse. Further research is needed to better define the role of ultrasound in a T2T management strategy in moderately-to-highly active RA.

To Contrast or Not to Contrast? On the Role of Contrast Enhancement in Hand MRI Studies of Patients with Rheumatoid Arthritis

Currently, clinical indications for the application of gadolinium-based contrast agents (GBCA) in magnetic resonance imaging (MRI) are increasingly being questioned. Consequently, this study aimed to evaluate the additional diagnostic value of contrast enhancement in MRI of the hand in patients with rheumatoid arthritis (RA). Thirty-one patients with RA (mean age, 50 ± 14 years (range, 18–72 years)) underwent morphologic MRI scans on a clinical 3 T scanner. MRI studies were analyzed based on (1) the Rheumatoid Arthritis Magnetic Resonance Imaging Score (RAMRIS) and (2) the GBCA-free RAMRIS version, termed RAMRIS Sine-Gadolinium-For-Experts (RAMRIS-SAFE), in which synovitis and tenosynovitis were assessed using the short-tau inversion-recovery sequence instead of the post-contrast T1-weighted sequence. The synovitis subscores in terms of Spearman’s ρ, as based on RAMRIS and RAMRIS-SAFE, were almost perfect (ρ = 0.937; p < 0.001), while the tenosynovitis subscores were less strongly correlated (ρ = 0.380 p = 0.035). Correlation between the total RAMRIS and RAMRIS-SAFE was also almost perfect (ρ = 0.976; p < 0.001). Inter-rater reliability in terms of Cohen’s κ was high (0.963 ≤ κ ≤ 0.925). In conclusion, RAMRIS-SAFE as the GBCA-free version of the well-established RAMRIS is a patient-friendly and resource-efficient alternative for assessing disease-related joint changes in RA. As patients with RA are subject to repetitive GBCA applications, non-contrast imaging protocols should be considered.

Applying Early Intervention Strategies to Autoimmune Skin Diseases. Is the Window of Opportunity Preclinical? A Dermato-Rheumatology Perspective

Many inflammatory skin diseases exhibit a chronic course with unsatisfactory long-term outcomes. Insights into early intervention approaches in other autoimmune contexts could improve the trajectory of lifelong diseases in terms of sustained remission or minimal disease activity, reduced requirement for therapy and medical resource use, and improved QoL. In both rheumatoid arthritis (RA) and psoriatic arthritis (PsA), we have learned that the timing and intensity of early interventions can influence later outcomes. Investigation into early RA, PsA, and systemic lupus erythematosus has shown that the optimal window of opportunity may even extend into asymptomatic preclinical phases of diseases. Notably, early and preclinical diseases may have pathogenic mechanisms and therapeutic targets that differ from those of the established disease. In this paper, we review the literature on these insights and discuss how similar research and therapeutic strategies may be investigated in cutaneous autoimmunity. We highlight the contribution of skin-resident cells to diseases that were previously thought to be initiated in the primary and secondary lymphoid organs of the immune system. We focus on two dermato‒rheumatology conditions-lupus and psoriasis-which share the commonality that effective early cutaneous disease therapy may have far-reaching implications on abrogating potentially severe systemic disease.

Ultrasound subclinical synovitis in anti-CCP+ at-risk individuals with MSK symptoms: an important and predictable stage in the RA continuum

Objectives

To investigate whether anti-CCP2-positive at-risk individuals with musculoskeletal (MSK) symptoms but without clinical synovitis (CCP2⁺ at-risk) develop US subclinical synovitis before inflammatory arthritis and if US subclinical synovitis can be predicted.

Methods

First, US scans of CCP2⁺ at-risk individuals who developed inflammatory arthritis (‘progressors’) were reviewed for subclinical synovitis prior to inflammatory arthritis development. Patients in whom the pre-progression US scan was negative but the scan was conducted >6 months before progression were excluded. Subsequently, regression analyses were performed to identify predictors of US synovitis in CCP2⁺ at-risk individuals without baseline US abnormalities who had one or more longitudinal US scan and a complete dataset.

Results

US subclinical synovitis was detected in one or more scan in 75 of 97 progressors (77.3%) {median time to inflammatory arthritis development from first evidence of US synovitis 26.5 weeks [interquartile range (IQR) 7–60]}, in whom one or more scan was available, excluding those with a negative scan >6 months from inflammatory arthritis development (n = 38). In 220 CCP2⁺ at-risk individuals with normal baseline US scans, who had one or more longitudinal US scan and a complete dataset, US synovitis was detected in 69/220 (31.4%) [median time to first developing US synovitis 56.4 weeks (IQR 33.0–112.0)]. In the multivariable analysis, only anti-CCP3 antibodies were predictive for the development of US synovitis [odds ratio 4.75 (95% CI 1.97, 11.46); P < 0.01].

Conclusions

In anti-CCP2⁺ at-risk individuals, a stage of subclinical synovitis usually precedes the development of inflammatory arthritis. Anti-CCP2⁺/CCP3⁺ individuals without clinical or US subclinical synovitis may represent the optimal window of opportunity for intervention to prevent joint disease.

In anti-CCP+ at-risk individuals, radiographic bone erosions are uncommon and are not associated with the development of clinical arthritis

OBJECTIVES

To investigate the prevalence, distribution and predictive value for the development of inflammatory arthritis (IA) of conventional radiography (CR) bone erosions (BE) in anti-CCP positive (CCP+) at-risk individuals with musculoskeletal (MSK) symptoms but without clinical synovitis.

METHODS

Baseline CR of the hands and feet of 418 CCP+ at-risk individuals were analysed. The presence of US-BE was explored in the anatomical areas in which CR-BE were reported. Hands and feet CR at the time of progression were analysed in a subset of individuals who developed IA (73/123, 59.3%). Logistic regression analyses were performed to calculate the predictive value of baseline CR-BE for the development of IA in 394 CCP+ individuals with ≥1 follow-up visit.

RESULTS

BE were detected in 17/418 (4.1%) CCP+ at-risk individuals (median Simple Erosions Narrowing Score-BE = 2.0, IQR: 1.0-2.0; median Sharp van der Heijde score-BE = 4.0, IQR: 3.0-8.5), most frequently in the foot joints (11/17, 64.7% individuals). A total of 123/394 (31.2%) CCP+ at-risk individuals developed IA; 7/17 (41.2%) with, and 116/377 (30.8%) without BE on CR (P = 0.37). US-BE were found in 4/7 (57.1%) individuals with CR-BE who developed IA, but only in 1/10 (10.0%) who did not. At the time of progression, new BE were detected in 4/73 (5.5%) CCP+ individuals on repeated CR. In the regression analyses, baseline CR-BE were not predictive for the development of IA.

CONCLUSIONS

In CCP+ at-risk individuals with MSK symptoms, CR-detected BE are uncommon and do not predict the development of IA.

Chronic Pain in Patients with Rheumatoid Arthritis

PURPOSE OF REVIEW

Chronic pain is highly prevalent in patients with rheumatoid arthritis (RA) and can cause various physical and psychological impairments. Unfortunately, the appropriate diagnosis of chronic pain syndromes in this population can be challenging because pain may be primary to RA-specific inflammation and/or secondary to other conditions, typically osteoarthritis (OA) and fibromyalgia (FM). This disparity further poses a clinical challenge, given that chronic pain can often be discordant or undetected with standard RA-specific surveillance strategies, including serological markers and imaging studies. In this review, we provide a robust exploration of chronic pain in the RA population with emphasis on epidemiology, mechanisms, and management strategies.

RECENT FINDINGS

Chronic pain associated with RA typically occurs in patients with anxiety, female sex, and elevated inflammatory status. Up to 50% of these patients are thought to have chronic pain despite appropriate inflammatory suppression, typically due to peripheral and central sensitization as well as secondary OA and FM. In addition to the standard-of-care management for OA and FM, patients with RA and chronic pain benefit from behavioral and psychological treatment options. Moreover, early and multimodal therapies, including non-pharmacological, pharmacological, interventional, and surgical strategies, exist, albeit with varying efficacy, to help suppress inflammation, provide necessary analgesia, and optimize functional outcomes. Overall, chronic pain in RA is a difficult entity for both patients and providers. Early diagnosis, improved understanding of its mechanisms, and initiation of early, targeted approaches to pain control may help to improve outcomes in this population.

Imaging of Joint and Soft Tissue Involvement in Systemic Lupus Erythematosus

PURPOSE OF REVIEW

To highlight the potential uses and applications of imaging in the assessment of the most common and relevant musculoskeletal (MSK) manifestations in systemic lupus erythematosus (SLE).

RECENT FINDINGS

Ultrasound (US) and magnetic resonance imaging (MRI) are accurate and sensitive in the assessment of inflammation and structural damage at the joint and soft tissue structures in patients with SLE. The US is particularly helpful for the detection of joint and/or tendon inflammation in patients with arthralgia but without clinical synovitis, and for the early identification of bone erosions. MRI plays a key role in the early diagnosis of osteonecrosis and in the assessment of muscle involvement (i.e., myositis and myopathy). Conventional radiography (CR) remains the traditional gold standard for the evaluation of structural damage in patients with joint involvement, and for the study of bone pathology. The diagnostic value of CR is affected by the poor sensitivity in demonstrating early structural changes at joint and soft tissue level. Computed tomography allows a detailed evaluation of bone damage. However, the inability to distinguish different soft tissues and the need for ionizing radiation limit its use to selected clinical circumstances. Nuclear imaging techniques are valuable resources in patients with suspected bone infection (i.e., osteomyelitis), especially when MRI is contraindicated. Finally, dual energy X-ray absorptiometry represents the imaging mainstay for the assessment and monitoring of bone status in patients with or at-risk of osteoporosis. Imaging provides relevant and valuable information in the assessment of MSK involvement in SLE.

What Is the Value of Ultrasound in Individuals 'At-Risk' of Rheumatoid Arthritis Who Do Not Have Clinical Synovitis?

The identification of biomarkers that help identify individuals at imminent risk of progression to rheumatoid arthritis (RA) is of crucial importance for disease prevention. In recent years, several studies have highlighted the value of musculoskeletal (MSK) ultrasound (US) in predicting progression to inflammatory arthritis (IA) in individuals ‘at-risk’ of RA. These studies have highlighted the following main aspects: first, in RA-related autoantibody-positive individuals, MSK symptoms seem to develop before ‘sub-clinical’ joint inflammation occurs on US. Second, the detection of ‘sub-clinical’ synovitis (and/or bone erosions) greatly increases the risk of IA development in these ‘at-risk’ individuals. US has a potential key role for better understanding the ‘pre-clinical’ stages in individuals ‘at-risk’ of RA, and for the early identification of those individuals at high risk of developing IA. Further research is needed to address questions on image analysis and standardization. In this review, we provide an overview of the most relevant studies which have investigated the value of US in the prediction of RA development in individuals ‘at-risk’ of RA who have MSK symptoms, but no clinical evidence of IA. We highlight recent insights, limitations, and future perspectives of US use in this important population.

The sonographic identification of cortical bone interruptions in rheumatoid arthritis: a morphological approach

Bone erosions are the hallmark of structural damage in rheumatoid arthritis (RA). Among imaging techniques, ultrasonography (US) has emerged as an accurate, reliable, repeatable, low-cost and non-invasive imaging modality to detect erosive changes in RA. However, small interruptions of the cortical bone detectable by last generation US equipment do not necessarily represent bone erosions. According to the available data, in addition to cortical bone interruption itself, only a few morphological US findings have been proposed to define RA bone erosions. However, other additional features may be considered to facilitate the interpretation of US cortical bone interruptions in RA. These could be summarised using the following four domains: size, site, shape and scenery. This hypothesis article provides a critical literature review of US features characteristic of RA bone erosions and pictorial evidence supporting the potential role of a morphological analysis in the US identification of bone erosions in RA patients.

Plain language summary

The ultrasonographic morphology of cortical interruptions is helpful for the identification of bone erosions in rheumatoid arthritis: the "four Ss" approach Bone erosions are characteristic features of rheumatoid arthritis. They are associated with a more aggressive disease and with irreversible physical disability. In recent years, ultrasonography has emerged as an accurate and reliable technique for the detection of bone erosions, that appear as interruptions of the cortical bone with variable size. However, cortical bone interruptions do not necessarily represent bone erosions. Since bone erosions represent the earliest evidence of the destructive behaviour of RA, their identification is crucial.Besides the cortical interruption itself, only a few morphological ultrasonographic features were proposed to characterise bone erosions in rheumatoid arthritis.We believe that a morphological approach, including size, site, shape and scenery, may be considered to facilitate the interpretation of ultrasonographic cortical bone interruptions in rheumatoid arthritis.In this hypothesis article we carried out a critical review of the scientific literature and provided extensive pictorial evidence of the ultrasonographic spectrum of cortical interruptions supporting the potential role of considering the "four Ss" for the ultrasonographic identification of bone erosions in rheumatoid arthritis.